fix(decky): a host saved under its own IP now shows the name it advertises

The panel captioned most rows with an IP address. The saved records were
the source: `hosts add` falls back to the address when the pairing path
knew nothing better, so `name` is literally "192.168.1.21" — and
`mergeHosts` took `s.name || s.addr` unconditionally. The fallback only
ever fired for an EMPTY name, so a name that was already a copy of the
address sailed through as if it were meaningful, and the row printed the
address twice: once as its title, once as its subtitle.

The friendly name was in hand the whole time. The row is built by joining
the saved record to the live advert, and that advert carries the host's
actual hostname — the join was already trusted for address, port, online
and OS, and only the name was read from the saved side alone.

So treat a name equal to the record's own address as the placeholder it is
and yield to the advert. A real saved name still wins, even when stale: it
may be one the user chose, and an advert must never silently overwrite it.
The comparison is against the SAVED address, so a host that moved DHCP
lease still recognises its old address as a placeholder rather than
mistaking it for a chosen name.

Checked against the Deck that reported this, over its actual store and
browse: three online rows turn into home-worker-5, ENRICOS-DESKTOP and
steamdeck, the four offline ones keep their address (nothing is
advertising a better name for them yet), and a user-chosen name survives a
conflicting advert.

.gitea/scripts/reconcile-latest.sh

@@ -0,0 +1,68 @@
+#!/usr/bin/env bash
+# Assert that a builder image's :latest is the SAME manifest as its content key, and
+# re-point it when it isn't.
+#
+# This is what we do instead of pinning consumers by @sha256: digest
+# (security-review-2026-08-05, H-6 — see the reasoning at the top of docker.yml). The
+# content key is a hash of the ci/ tree, so "which image should :latest be?" has an
+# answer derivable from the commit alone. Checking it on every run turns :latest from a
+# tag someone remembered to move into a function of the tree.
+#
+# Two different things make them diverge and neither is distinguishable from here:
+#
+#   - Someone overwrote :latest out of band. Post-fix that needs the push credential,
+#     but it is exactly the H-6 attack and it must not pass silently.
+#   - ci/ was reverted. The older key is already a cache hit, so nothing rebuilds and
+#     nothing re-points :latest — it stays on the newer build forever while every
+#     consumer pulls a builder that does not match the tree it is building. That bug
+#     predates this script.
+#
+# Both are repaired identically, so: repair, and shout. Failing the build instead would
+# turn a legitimate revert into a red main with no way forward.
+#
+# Reads go to the anonymous port, the single write to the authenticated one.
+set -euo pipefail
+
+IMAGE="${1:?usage: reconcile-latest.sh <image> <content-key>}"
+KEY="${2:?usage: reconcile-latest.sh <image> <content-key>}"
+: "${CI_REGISTRY:?CI_REGISTRY not set}"
+: "${CI_REGISTRY_PUSH:?CI_REGISTRY_PUSH not set}"
+: "${CI_REGISTRY_PASSWORD:?CI_REGISTRY_PASSWORD not set}"
+
+ACCEPT='Accept: application/vnd.docker.distribution.manifest.v2+json, application/vnd.oci.image.manifest.v1+json, application/vnd.oci.image.index.v1+json, application/vnd.docker.distribution.manifest.list.v2+json'
+
+# Digest of a tag, or empty if the tag does not exist. Never fails the script itself —
+# "missing" is a state this has to reason about, not an error to abort on.
+digest_of() {
+  curl -sfI -H "$ACCEPT" "http://$CI_REGISTRY/v2/$IMAGE/manifests/$1" 2>/dev/null \
+    | tr -d '\r' | sed -n 's/^[Dd]ocker-[Cc]ontent-[Dd]igest: //p' || true
+}
+
+key_digest=$(digest_of "$KEY")
+latest_digest=$(digest_of latest)
+
+if [ -z "$key_digest" ]; then
+  echo "::error::$IMAGE:$KEY has no manifest — the build or push above did not land"
+  exit 1
+fi
+
+if [ "$key_digest" = "$latest_digest" ]; then
+  echo "$IMAGE:latest == :$KEY ($key_digest)"
+  exit 0
+fi
+
+echo "::warning::$IMAGE:latest did not match its content key :$KEY — re-pointing it. If ci/ was not just reverted, someone overwrote this tag out of band: check the registry access log on home-ci-core."
+echo "  was:    ${latest_digest:-<no :latest tag>}"
+echo "  wanted: $key_digest  (:$KEY)"
+
+tmp=$(mktemp)
+trap 'rm -f "$tmp"' EXIT
+media_type=$(curl -sfI -H "$ACCEPT" "http://$CI_REGISTRY/v2/$IMAGE/manifests/$KEY" \
+  | tr -d '\r' | sed -n 's/^[Cc]ontent-[Tt]ype: //p')
+curl -sf -H "$ACCEPT" -o "$tmp" "http://$CI_REGISTRY/v2/$IMAGE/manifests/$KEY"
+curl -sf -u "ci:$CI_REGISTRY_PASSWORD" -X PUT -H "Content-Type: $media_type" \
+  --data-binary @"$tmp" "http://$CI_REGISTRY_PUSH/v2/$IMAGE/manifests/latest"
+
+now=$(digest_of latest)
+[ "$now" = "$key_digest" ] || { echo "::error::re-point failed: :latest is $now"; exit 1; }
+echo "$IMAGE:latest re-pointed to $key_digest"

.gitea/workflows/decky.yml

@@ -46,7 +46,10 @@ env:
   REGISTRY: git.unom.io
   OWNER: unom
   PACKAGE: punktfunk-decky        # generic-registry package name
-  PLUGIN: punktfunk               # plugin.json "name" == zip top-level dir
+  # The plugin's ON-DISK dir == the zip's top-level dir. Deliberately NOT plugin.json "name"
+  # (that is the brand-cased label Decky lists, and it locates a plugin by matching it, not by
+  # the folder) — see clients/decky/scripts/package.sh.
+  PLUGIN: punktfunk
 
 jobs:
   build-publish:

.gitea/workflows/docker.yml

@@ -3,13 +3,18 @@
 # Two very different image families now:
 #
 #   BUILDER images (punktfunk-rust-ci{,-noble,-arm64cross}, punktfunk-fedora{,44}-rpm)
-#     live on the LAN registry (home-ci-core, 192.168.1.58:5010 — unom/infra
-#     runners/ci-core/) and are CONTENT-KEYED: the tag is a hash of what they are built
-#     from (the ci/ tree, + rust-toolchain.toml for the cross image), and a build only
-#     happens when that key has no manifest yet. A push that doesn't touch ci/ costs one
-#     curl per image (~seconds), pushes nothing over the WAN, and mints no per-SHA tag
-#     debris on the runners — the failure mode that filled the fleet's disks. `:latest`
-#     is re-pushed alongside every new key and is what the consuming workflows pin.
+#     live on the LAN registry (home-ci-core — unom/infra runners/ci-core/) and are
+#     CONTENT-KEYED: the tag is a hash of what they are built from (the ci/ tree, +
+#     rust-toolchain.toml for the cross image), and a build only happens when that key
+#     has no manifest yet. A push that doesn't touch ci/ costs one curl per image
+#     (~seconds), pushes nothing over the WAN, and mints no per-SHA tag debris on the
+#     runners — the failure mode that filled the fleet's disks. `:latest` is re-pushed
+#     alongside every new key and is what the consuming workflows pin.
+#
+#     READS come from :5010 and need no credential. WRITES go to :5011 and need
+#     CI_REGISTRY_PASSWORD. Same store behind both — a registry keys by repository name,
+#     not by the host:port the client used — so an image pushed to :5011 is the same
+#     image every consumer pulls from :5010.
 #
 #   APP images (punktfunk-web, punktfunk-docs) are deployables: they keep going to the
 #     Gitea registry (git.unom.io) with :latest + :sha-<8> (+ :vX.Y.Z on tags), because
@@ -17,26 +22,38 @@
 #
 # Host and clients are intentionally NOT containerized (see CLAUDE.md "What's left").
 #
-# REGISTRY_TOKEN: repo Actions secret, a PAT with write:package scope (app images only —
-# the LAN registry is unauthenticated inside the LAN).
+# REGISTRY_TOKEN: repo Actions secret, a PAT with write:package scope (app images).
+# CI_REGISTRY_PASSWORD: repo Actions secret, the LAN registry's push credential for user
+# `ci`. Generated on ci-core into /srv/ci/stack/registry-secret; rotate in both places.
 #
-# ⚠ OPEN FINDING — security-review-2026-08-05 H-6. That parenthetical is the whole problem.
-# Every secret-bearing job in this repo runs INSIDE an image pulled from this registry by a
-# MUTABLE tag (`:latest`), and the registry accepts pushes from any LAN peer. Attacker position #1
-# of the project's own threat model — an unauthenticated LAN peer — therefore does not need to
-# break any signing logic: they push one tag, and the next android.yml run executes their code in
-# the same job that does `echo "$RELEASE_KEYSTORE_BASE64" | base64 -d > release.jks`. Same shape
-# for rpm.yml (RPM_GPG_PRIVATE_KEY), android-promote.yml (SERVICE_ACCOUNT_JSON), and every other
-# consumer listed by `grep -l 192.168.1.58:5010 .gitea/workflows/`.
+# --- security-review-2026-08-05 H-6, FIXED 2026-08-05 -------------------------------
+# The registry used to accept anonymous pushes from any LAN peer, and every
+# secret-bearing job in this repo runs INSIDE an image pulled from it. Attacker
+# position #1 of the project's own threat model did not need to break any signing
+# logic: push one tag, and the next android.yml run executes their code in the same job
+# that does `echo "$RELEASE_KEYSTORE_BASE64" | base64 -d > release.jks`. Same shape for
+# rpm.yml (RPM_GPG_PRIVATE_KEY) and android-promote.yml (SERVICE_ACCOUNT_JSON).
 #
-# The fix is two halves and only one of them lives in this repo:
-#   1. INFRA (unom/infra, runners/ci-core/): put auth in front of the registry, or move the
-#      builder images to git.unom.io where pushes are already authenticated.
-#   2. HERE: once pushes are authenticated, pin consumers by `@sha256:` digest rather than
-#      `:latest`, so a compromised push cannot retroactively change what a green run built.
-#      Pinning by tag — including the content-keyed `$KEY` tags below — is NOT sufficient while
-#      the registry is open, because a tag can simply be overwritten.
-# Neither half is done. The content-keying below bounds rebuild churn; it is not a trust boundary.
+# The infra half is done (unom/infra runners/ci-core/): :5010 serves GET/HEAD only and
+# refuses everything else with 405, :5011 demands basic auth on every request. The half
+# in this file is done below: pushes and release-tag manifest PUTs authenticate.
+#
+# ⚠ On the second half as the review originally worded it — "pin consumers by @sha256:
+# digest". We deliberately do something else, because after authentication the digest
+# pin no longer buys what it was meant to buy. The set of people who can overwrite a tag
+# is now exactly the set who can push to main and edit a pinned digest in this very
+# file: a pin defends against nobody it did not already trust, while costing a
+# two-commit dance on every ci/ change (~3x a month) during which consumers silently run
+# a builder image that predates the ci/ change they are testing.
+#
+# What actually closes the residual gap — a tag quietly overwritten out of band — is
+# making :latest a CHECKED function of the tree instead of a tag someone remembered to
+# move. The "Reconcile :latest" step below asserts on every run that :latest and
+# :ck-$KEY are the same digest, repairs it when they are not, and says so loudly. That
+# catches an out-of-band overwrite on the next push to main, needs no churn, and fixes
+# a real pre-existing bug on the side: reverting ci/ used to leave :latest pointing at
+# the newer build forever. Revisit inline digest pins if the push credential ever leaves
+# the maintainer trust set.
 #
 # Bootstrap note: consuming workflows pull <LAN>/punktfunk-rust-ci:latest, so the LAN
 # registry must hold a seeded :latest once (done 2026-07-29 from the last Gitea-registry
@@ -60,7 +77,10 @@ on:
 env:
   REGISTRY: git.unom.io
   OWNER: unom
+  # Read port (anonymous, GET/HEAD only) and write port (basic auth). Two doors onto
+  # one store; see the header.
   CI_REGISTRY: 192.168.1.58:5010
+  CI_REGISTRY_PUSH: 192.168.1.58:5011
 
 jobs:
   builders:
@@ -116,21 +136,40 @@ jobs:
             echo "hit=false" >> "$GITHUB_OUTPUT"
           fi
 
+      # Tagged for the WRITE port: :5010 refuses a push outright, so a tag that names it
+      # can only fail. Consumers still pull the identical image from :5010.
       - name: Build
         if: steps.exists.outputs.hit == 'false'
         # --pull is cheap now: base images come through the ci-core pull-through mirror.
         run: |
           docker build --pull ${{ matrix.buildargs }} \
             -f "${{ matrix.dockerfile }}" \
-            -t "$CI_REGISTRY/${{ matrix.image }}:$KEY" \
-            -t "$CI_REGISTRY/${{ matrix.image }}:latest" \
+            -t "$CI_REGISTRY_PUSH/${{ matrix.image }}:$KEY" \
+            -t "$CI_REGISTRY_PUSH/${{ matrix.image }}:latest" \
             ci
 
+      - name: Log in to the LAN registry
+        run: |
+          echo "$CI_REGISTRY_PASSWORD" | docker login "$CI_REGISTRY_PUSH" -u ci --password-stdin
+        env:
+          CI_REGISTRY_PASSWORD: ${{ secrets.CI_REGISTRY_PASSWORD }}
+
       - name: Push
         if: steps.exists.outputs.hit == 'false'
         run: |
-          docker push "$CI_REGISTRY/${{ matrix.image }}:$KEY"
-          docker push "$CI_REGISTRY/${{ matrix.image }}:latest"
+          docker push "$CI_REGISTRY_PUSH/${{ matrix.image }}:$KEY"
+          docker push "$CI_REGISTRY_PUSH/${{ matrix.image }}:latest"
+
+      # :latest must be whatever ci/ says it is, on every run — not only on the runs that
+      # happened to build. Two things break that: an out-of-band overwrite (the H-6
+      # attack, now only reachable by someone holding the push credential), and a plain
+      # revert of ci/, which leaves :latest on the newer build because the older key is
+      # already a cache hit and nothing re-points it. Both look identical from here and
+      # both are repaired the same way, so repair and shout rather than fail the build.
+      - name: Reconcile :latest with the content key
+        run: .gitea/scripts/reconcile-latest.sh "${{ matrix.image }}" "$KEY"
+        env:
+          CI_REGISTRY_PASSWORD: ${{ secrets.CI_REGISTRY_PASSWORD }}
 
       # A release pins reproducible builder images without any rebuild: copy the key's
       # manifest to a vX.Y.Z tag via the registry API (no image bytes move).
@@ -142,8 +181,19 @@ jobs:
             | tr -d '\r' | sed -n 's/^[Cc]ontent-[Tt]ype: //p')
           curl -sf -H "$ACCEPT" -o /tmp/manifest.json \
             "http://$CI_REGISTRY/v2/${{ matrix.image }}/manifests/$KEY"
-          curl -sf -X PUT -H "Content-Type: $MT" --data-binary @/tmp/manifest.json \
-            "http://$CI_REGISTRY/v2/${{ matrix.image }}/manifests/$GITHUB_REF_NAME"
+          curl -sf -u "ci:$CI_REGISTRY_PASSWORD" -X PUT -H "Content-Type: $MT" \
+            --data-binary @/tmp/manifest.json \
+            "http://$CI_REGISTRY_PUSH/v2/${{ matrix.image }}/manifests/$GITHUB_REF_NAME"
+        env:
+          CI_REGISTRY_PASSWORD: ${{ secrets.CI_REGISTRY_PASSWORD }}
+
+      # Today the job container is ephemeral (the ubuntu-24.04 label is a docker://
+      # image), so the credential docker login wrote would die with it anyway. Don't
+      # make that a load-bearing assumption about a runner label somebody may change to
+      # a host runner later.
+      - name: Log out of the LAN registry
+        if: always()
+        run: docker logout "$CI_REGISTRY_PUSH" || true
 
   # The aarch64 CROSS builder — a SEPARATE job because it is `FROM punktfunk-rust-ci:latest`
   # (the LAN copy) and so must not race the matrix entry that publishes that base. Consumed
@@ -182,15 +232,26 @@ jobs:
         run: |
           docker build --pull \
             -f ci/rust-ci-arm64cross.Dockerfile \
-            -t "$CI_REGISTRY/$IMAGE:$KEY" \
-            -t "$CI_REGISTRY/$IMAGE:latest" \
+            -t "$CI_REGISTRY_PUSH/$IMAGE:$KEY" \
+            -t "$CI_REGISTRY_PUSH/$IMAGE:latest" \
             .
 
+      - name: Log in to the LAN registry
+        run: |
+          echo "$CI_REGISTRY_PASSWORD" | docker login "$CI_REGISTRY_PUSH" -u ci --password-stdin
+        env:
+          CI_REGISTRY_PASSWORD: ${{ secrets.CI_REGISTRY_PASSWORD }}
+
       - name: Push
         if: steps.exists.outputs.hit == 'false'
         run: |
-          docker push "$CI_REGISTRY/$IMAGE:$KEY"
-          docker push "$CI_REGISTRY/$IMAGE:latest"
+          docker push "$CI_REGISTRY_PUSH/$IMAGE:$KEY"
+          docker push "$CI_REGISTRY_PUSH/$IMAGE:latest"
+
+      - name: Reconcile :latest with the content key
+        run: .gitea/scripts/reconcile-latest.sh "$IMAGE" "$KEY"
+        env:
+          CI_REGISTRY_PASSWORD: ${{ secrets.CI_REGISTRY_PASSWORD }}
 
       - name: Tag for release
         if: startsWith(github.ref, 'refs/tags/v')
@@ -200,8 +261,15 @@ jobs:
             | tr -d '\r' | sed -n 's/^[Cc]ontent-[Tt]ype: //p')
           curl -sf -H "$ACCEPT" -o /tmp/manifest.json \
             "http://$CI_REGISTRY/v2/$IMAGE/manifests/$KEY"
-          curl -sf -X PUT -H "Content-Type: $MT" --data-binary @/tmp/manifest.json \
-            "http://$CI_REGISTRY/v2/$IMAGE/manifests/$GITHUB_REF_NAME"
+          curl -sf -u "ci:$CI_REGISTRY_PASSWORD" -X PUT -H "Content-Type: $MT" \
+            --data-binary @/tmp/manifest.json \
+            "http://$CI_REGISTRY_PUSH/v2/$IMAGE/manifests/$GITHUB_REF_NAME"
+        env:
+          CI_REGISTRY_PASSWORD: ${{ secrets.CI_REGISTRY_PASSWORD }}
+
+      - name: Log out of the LAN registry
+        if: always()
+        run: docker logout "$CI_REGISTRY_PUSH" || true
 
   # Deployable app images — unchanged flow, Gitea registry, per-SHA + release tags.
   apps:

api/openapi.json

@@ -10,7 +10,7 @@
       "name": "MIT OR Apache-2.0",
       "identifier": "MIT OR Apache-2.0"
     },
-    "version": "0.23.0"
+    "version": "0.24.0"
   },
   "paths": {
     "/api/v1/clients": {
@@ -1052,7 +1052,7 @@
           "library"
         ],
         "summary": "Fetch one cover-art image for a library entry",
-        "description": "Resolves `kind` (`portrait` | `hero` | `logo` | `header`) for the given library id and streams\nthe image bytes. For a Steam title, the host's own local Steam cache is tried first (exact —\nit's what the user's Steam client already shows for it), the public Steam CDN's flat URL\nconvention as a fallback (newer titles' CDN assets can live at a per-asset-hash path the host\ncan't predict, in which case this 404s and the client falls through to its next art candidate).\nOnly Steam ids are backed today; any other store 404s.",
+        "description": "Resolves `kind` (`portrait` | `hero` | `logo` | `header`) for the given library id and streams\nthe image bytes. Any id stored in the host's catalog (manual entries, provider-synced entries,\nand a library plugin's claimed-store entries) serves its local art file. A Steam title falls back\nto the in-host scanner's resolver: the host's own local Steam cache first (exact — it's what the\nuser's Steam client already shows for it), the public Steam CDN's flat URL convention second\n(newer titles' CDN assets can live at a per-asset-hash path the host can't predict, in which case\nthis 404s and the client falls through to its next art candidate).",
         "operationId": "getLibraryArt",
         "parameters": [
           {
@@ -1307,7 +1307,7 @@
           "library"
         ],
         "summary": "Replace a provider's library entries (declarative reconcile)",
-        "description": "Atomically replaces the full entry set owned by `{provider}` (RFC §8): the payload is the\nprovider's desired list, keyed by its own stable `external_id` — the host diffs, keeps each\nsurviving title's host id stable across reconciles, drops orphans, and never touches manual\nentries or other providers'. An empty array removes everything the provider owns. Emits\n`library.changed` with the provider as `source`.",
+        "description": "Atomically replaces the full entry set owned by `{provider}` (RFC §8): the payload is the\nprovider's desired list, keyed by its own stable `external_id` — the host diffs, keeps each\nsurviving title's host id stable across reconciles, drops orphans, and never touches manual\nentries or other providers'. An empty array removes everything the provider owns. Emits\n`library.changed` with the provider as `source`.\n\n`?store=` additionally **claims** that store for the provider: its entries then surface with\ndeterministic `<store>:<external_id>` ids and the store's own badge, instead of opaque\n`custom:<id>` ones — which is what lets a library plugin reproduce the entries an in-host scanner\nused to produce, right down to the GameStream app ids and client-side art caches. One provider\nper store; a second claimant gets 409. While a claim is held the matching built-in scanner is\nsuppressed, so the two never double-list. The claim is released by `DELETE`, not by an empty\nreconcile (a store can legitimately have zero installed titles).",
         "operationId": "reconcileProviderEntries",
         "parameters": [
           {
@@ -1318,6 +1318,15 @@
             "schema": {
               "type": "string"
             }
+          },
+          {
+            "name": "store",
+            "in": "query",
+            "description": "Claim this store for the provider ([a-z0-9_-], `custom`/`manual` reserved)",
+            "required": false,
+            "schema": {
+              "type": "string"
+            }
           }
         ],
         "requestBody": {
@@ -1348,7 +1357,7 @@
             }
           },
           "400": {
-            "description": "Invalid provider id or payload",
+            "description": "Invalid provider id, store id, or payload",
             "content": {
               "application/json": {
                 "schema": {
@@ -1367,6 +1376,16 @@
               }
             }
           },
+          "409": {
+            "description": "That store is already claimed by another provider",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/ApiError"
+                }
+              }
+            }
+          },
           "500": {
             "description": "Could not persist the catalog",
             "content": {
@@ -4159,7 +4178,8 @@
           "tier",
           "platforms",
           "compatible",
-          "update_available"
+          "update_available",
+          "categories"
         ],
         "properties": {
           "author": {
@@ -4172,6 +4192,13 @@
             ],
             "description": "A revocation covering the catalogued version — do not offer this without shouting."
           },
+          "categories": {
+            "type": "array",
+            "items": {
+              "type": "string"
+            },
+            "description": "What kind of plugin this is — the console filters Browse by these, and the Game sources\nsurface's \"Add a source\" rail shows exactly the `library` ones (design D5/D6)."
+          },
           "compatible": {
             "type": "boolean",
             "description": "Can this host install it?"
@@ -4179,6 +4206,13 @@
           "description": {
             "type": "string"
           },
+          "detected": {
+            "type": [
+              "boolean",
+              "null"
+            ],
+            "description": "Whether the launcher this plugin scans looks **installed on this host** (design D8), from the\nindex's own existence probes. `null` = the entry declares no probes for this platform, which\nthe console renders as \"unknown\" rather than \"not installed\"."
+          },
           "homepage": {
             "type": [
               "string",
@@ -4365,6 +4399,17 @@
                 ],
                 "description": "The external provider owning this entry (RFC §8), set ONLY by the provider reconcile\nAPI — `None` = a manual entry, which no provider operation ever touches, and which the\nmanual CRUD alone may edit (the converse holds too: manual CRUD refuses provider-owned\nentries, so ownership is never ambiguous)."
               },
+              "role": {
+                "$ref": "#/components/schemas/GameRole",
+                "description": "Whether this entry is a game or the launcher itself — see [`GameRole`]."
+              },
+              "store": {
+                "type": [
+                  "string",
+                  "null"
+                ],
+                "description": "The **store this entry was claimed under** (D2), stamped by a `?store=`-qualified reconcile.\n`None` = an unclaimed provider entry or a manual one, both of which surface as `custom`.\n\nMaterialized onto the entry rather than looked up in [`Catalog::claims`] on every read so an\nentry is self-describing: its id and its `store` badge derive from the entry alone, and stay\ncorrect even while the claim map is being rewritten."
+              },
               "title": {
                 "type": "string"
               }
@@ -4409,6 +4454,10 @@
                 },
                 "description": "Per-title prep/undo steps — commands run as the host user; operator-privileged config."
               },
+              "role": {
+                "$ref": "#/components/schemas/GameRole",
+                "description": "Whether this entry is a game or the launcher itself — see [`GameRole`]. A hand-added launcher\nentry is legal (an operator may want a \"Steam\" tile without installing the steam plugin)."
+              },
               "title": {
                 "type": "string"
               }
@@ -4467,6 +4516,17 @@
         "type": "object",
         "description": "What an operator (or a provider plugin) can tell the host about recognizing a title — the wire\nhalf of [`DetectSpec`], and the only part of it that is ever accepted from outside.\n\nDeliberately a **subset**: the store-derived signals (a Steam appid, a launcher's environment\nmarker) are things the host discovers for itself and would be meaningless — or dangerous — to take\non someone's word. What is left is what a provider genuinely knows and the host cannot guess: where\nthe title is installed, which executable is the game, what the process is called. All three are\noptional; supplying none is the same as supplying no hint at all.\n\nNever returned by the catalog API — see the module docs on why detect data does not cross the wire\noutbound.",
         "properties": {
+          "env_marker": {
+            "oneOf": [
+              {
+                "type": "null"
+              },
+              {
+                "$ref": "#/components/schemas/EnvMarker",
+                "description": "A launcher-stamped environment marker (D3) — see [`EnvMarker`]."
+              }
+            ]
+          },
           "exe": {
             "type": [
               "string",
@@ -4487,6 +4547,15 @@
               "null"
             ],
             "description": "The executable's file name (`Hades.exe`), when its location isn't fixed. Weakest of the three\n— see [`DetectSpec::process_name`]."
+          },
+          "steam_appid": {
+            "type": [
+              "integer",
+              "null"
+            ],
+            "format": "int32",
+            "description": "The Steam appid, for a title Steam itself installed (D3). On Linux this is the **sharpest**\nsignal that exists — Steam wraps every launch, native or Proton, in\n`reaper SteamLaunch AppId=<appid>`, whose lifetime is exactly the game's — so without it a\nsteam plugin's lease tracking would degrade from reaper-exact to install-dir prefix matching.",
+            "minimum": 0
           }
         }
       },
@@ -4715,6 +4784,27 @@
           }
         }
       },
+      "EnvMarker": {
+        "type": "object",
+        "description": "An environment variable a launcher stamps onto the game's process, identifying it.\n\nSerializable because it is now half of the inbound [`DetectHint`] too (D3) — a library plugin\nthat knows its launcher's marker (Heroic's `HEROIC_APP_NAME`, load-bearing under Proton) has to\nbe able to say so, since after extraction the host no longer reads that launcher's files itself.",
+        "required": [
+          "key"
+        ],
+        "properties": {
+          "key": {
+            "type": "string",
+            "description": "The variable name (e.g. `HEROIC_GAME_ID`).",
+            "example": "HEROIC_APP_NAME"
+          },
+          "value": {
+            "type": [
+              "string",
+              "null"
+            ],
+            "description": "The exact value to require, when the launcher's value identifies *this* title. `None` matches\nthe key's mere presence — only safe for launchers that run one game at a time."
+          }
+        }
+      },
       "EventKind": {
         "oneOf": [
           {
@@ -5165,6 +5255,10 @@
                 ],
                 "description": "The external provider owning this entry (custom-store entries synced by a provider\nplugin, RFC §8) — `None` for installed-store titles and manual custom entries. The\nconsole uses it for attribution; `GET /library?provider=` filters on it."
               },
+              "role": {
+                "$ref": "#/components/schemas/GameRole",
+                "description": "Whether this entry is a game or the launcher itself — see [`GameRole`]."
+              },
               "store": {
                 "type": "string",
                 "description": "Which store surfaced it: `\"steam\"` or `\"custom\"`.",
@@ -5296,6 +5390,14 @@
           }
         }
       },
+      "GameRole": {
+        "type": "string",
+        "description": "What a library entry *is* — an ordinary title, or the launcher application itself (Steam Big\nPicture, Heroic, Playnite fullscreen). Purely a presentation hint: a launcher entry launches,\nleases and lists exactly like a game (design D4), and clients that don't know the field render it\nas a plain tile. Serde-default `game` and skip-serialized when default, so the wire is unchanged\nfor every entry that doesn't opt in.",
+        "enum": [
+          "game",
+          "launcher"
+        ]
+      },
       "GameSession": {
         "type": "string",
         "description": "How a session that **launches a game** (a library id on the Hello / apps.json / Decky pin) is\nserved (`design/gamemode-and-dedicated-sessions.md` §5.2). Orthogonal to the preset/lifecycle axes\n— a top-level [`DisplayPolicy`] field, NOT part of [`EffectivePolicy`], so a preset never clobbers\nit. Linux-only in effect (a launching Windows session opens into the one desktop).",
@@ -6334,6 +6436,13 @@
           "title"
         ],
         "properties": {
+          "category": {
+            "type": [
+              "string",
+              "null"
+            ],
+            "description": "What KIND of plugin this is (`^[a-z][a-z0-9-]{0,31}$`), top-level rather than under `ui`\nbecause it describes the plugin, not its surface. The console knows one value today —\n`library` — which it filters **out of the nav**: six installed scanner plugins would otherwise\nflood the sidebar, and their real entry point is the Game sources surface (design D5). A\nlibrary plugin that genuinely wants its own page (rom-manager, which is much more than a\nscanner) simply omits the category."
+          },
           "title": {
             "type": "string",
             "description": "Human-readable title for the console nav entry (1–64 chars; control chars stripped)."
@@ -6366,6 +6475,13 @@
           "title"
         ],
         "properties": {
+          "category": {
+            "type": [
+              "string",
+              "null"
+            ],
+            "description": "The plugin's kind — see [`PluginRegistration::category`]."
+          },
           "id": {
             "type": "string"
           },
@@ -6604,6 +6720,10 @@
                 },
                 "description": "Per-title prep/undo steps — commands run as the host user; operator-privileged config."
               },
+              "role": {
+                "$ref": "#/components/schemas/GameRole",
+                "description": "Whether this entry is a game or the launcher itself — see [`GameRole`]. A library plugin\nemits its `launchers(cfg)` entries with `role: \"launcher\"`."
+              },
               "title": {
                 "type": "string"
               }
@@ -6780,26 +6900,46 @@
       },
       "ScannerInfo": {
         "type": "object",
-        "description": "One installed-store scanner this host build supports, with its enable state — the unit the\nconsole renders a toggle for. The list is platform-gated at compile time (the scanners are),\nso the console never shows a toggle that cannot do anything on this host.",
+        "description": "One **game source** on this host, with its enable state — the unit the console renders a toggle\nfor. A source is either a scanner compiled into this build or a plugin that reconciles entries in\n(WP2.6); the console treats them identically, which is what makes the extraction invisible.",
         "required": [
           "id",
           "label",
-          "enabled"
+          "enabled",
+          "origin"
         ],
         "properties": {
           "enabled": {
             "type": "boolean",
-            "description": "Whether this host runs the scanner (default true)."
+            "description": "Whether this host runs the source (default true)."
+          },
+          "entries": {
+            "type": [
+              "integer",
+              "null"
+            ],
+            "description": "How many entries this source currently contributes. `None` for a built-in scanner, whose\ncount would mean walking every launcher's files just to render a toggle.",
+            "minimum": 0
           },
           "id": {
             "type": "string",
-            "description": "Stable scanner id — the same string the scanner's entries carry in their `store` field.",
+            "description": "Stable source id — the same string this source's entries carry in their `store` field. For a\nplugin source it is also its provider id and its store claim: one string, by construction, so\na user's disabled state survives a built-in scanner being replaced by its plugin.",
             "example": "steam"
           },
           "label": {
             "type": "string",
             "description": "Human-facing name for the console toggle.",
             "example": "Steam"
+          },
+          "origin": {
+            "$ref": "#/components/schemas/SourceOrigin",
+            "description": "Where the source comes from: `builtin` (a scanner in this host build) or `plugin`."
+          },
+          "provider": {
+            "type": [
+              "string",
+              "null"
+            ],
+            "description": "The provider id backing a `plugin` source — absent for a built-in scanner."
           }
         }
       },
@@ -6962,6 +7102,14 @@
           }
         }
       },
+      "SourceOrigin": {
+        "type": "string",
+        "description": "Where a [`ScannerInfo`] comes from.",
+        "enum": [
+          "builtin",
+          "plugin"
+        ]
+      },
       "SourceView": {
         "type": "object",
         "description": "A configured catalog source and how its last refresh went.",

clients/android/app/src/main/kotlin/io/unom/punktfunk/StatsOverlay.kt

@@ -26,13 +26,25 @@ import kotlin.math.roundToInt
  * presentsWindow, presenterActive, feedP50Ms, codecP50Ms, skippedOverflowWindow]`. Every read
  * is length-guarded, so an older native lib simply omits the lines it can't feed.
  *
+ * The shown `display` and `end-to-end` numbers EXCLUDE the OS present floor (see [osFloorMs]) at
+ * every tier, and the detailed tier names what was excluded on its own line. The principle is the
+ * Apple client's: metrics report what Punktfunk controls, so the compositor's own latch and scanout
+ * — which no client can pace under — is reported rather than charged. It also stops the HUD reading
+ * worse than it is: the usual Android streaming overlays stop measuring at decode-complete, so a
+ * headline that carried the compositor's wait was compared against numbers that never contained it.
+ *
+ * The RAW figures are not lost — the native 1 Hz `pf.present` logcat line keeps `paceMs`, `latchMs`
+ * and `e2eMs` unshaved, so a HUD-off A/B and any cross-session comparison still work off the
+ * untouched numbers.
+ *
  * [verbosity] selects how many lines render (each tier a superset of the last — see
  * [StatsVerbosity]):
  * - [StatsVerbosity.COMPACT] — one line, `fps · end-to-end ms · Mb/s` (+ a loss flag).
  * - [StatsVerbosity.NORMAL] — the res/fps/Mb·s line, the end-to-end p50/p95 headline, and the
  *   reliability counters (18–21) when nonzero.
- * - [StatsVerbosity.DETAILED] — also the decoder label, the video-feed descriptor (10–13), and the
- *   stage equation (14/15, split into `host + network` when the Phase-2 terms at 16/17 are nonzero).
+ * - [StatsVerbosity.DETAILED] — also the decoder label, the video-feed descriptor (10–13), the
+ *   stage equation (14/15, split into `host + network` when the Phase-2 terms at 16/17 are nonzero),
+ *   and the excluded-floor line when one was measured.
  * [StatsVerbosity.OFF] renders nothing. Older native layouts simply omit the lines they lack (the
  * counter line falls back to the cumulative `lostTotal` at index 9 on a pre-window lib).
  */
@@ -95,9 +107,15 @@ internal fun StatsOverlay(
             // equation gains its `display` term; otherwise (older lib / no callbacks) the endpoint
             // honestly stays capture→decoded — the equation always tiles the headline interval.
             val dispValid = s.size >= 26 && s[22] != 0.0
+            // The OS present floor this window (see [osFloorMs]) is excluded from every shown
+            // display / end-to-end number, at every tier — it is pipeline depth no client can pace
+            // under, so charging it to Punktfunk made our HUD read worse than clients that simply
+            // never measure it. 0.0 when unmeasured, which leaves the numbers exactly as raw as
+            // they were.
+            val floorMs = osFloorMs(s)
             val tag = if (skew) "" else " (same-host clock)"
             val (p50, p95, endpoint) = if (dispValid) {
-                Triple(s[24], s[25], "capture→displayed")
+                Triple(shave(s[24], floorMs), shave(s[25], floorMs), "capture→displayed")
             } else {
                 Triple(s[2], s[3], "capture→decoded")
             }
@@ -120,6 +138,11 @@ internal fun StatsOverlay(
                 // dropping/serializing, an fps deficit is upstream.
                 val split = s.size >= 30 && s[29] != 0.0 && (s[26] > 0 || s[27] > 0)
                 val displayTerm = when {
+                    // Floor excluded: what remains of the `display` term is the half Punktfunk
+                    // owns (the presenter's pace wait), and the excluded line below carries the
+                    // latch — printing the split too would report the same milliseconds twice.
+                    dispValid && floorMs > 0 ->
+                        " + display ${"%.1f".format(shave(s[23], floorMs))}"
                     dispValid && split ->
                         " + display ${"%.1f".format(s[23])} " +
                             "(pace ${"%.1f".format(s[26])} + latch ${"%.1f".format(s[27])})"
@@ -143,16 +166,14 @@ internal fun StatsOverlay(
                     "= $hostTerms + $decodeTerm$displayTerm$presents",
                     Color.White,
                 )
-                // Metric fairness: the Apple client's HUD shaves ~2 refresh periods of OS
-                // pipeline floor off its shown display/end-to-end; Android shows raw. This twin
-                // applies the same shave so iPhone↔Android HUD numbers compare directly.
-                if (dispValid && hz > 0) {
-                    val shave = 2000.0 / hz
+                // What the numbers above leave out, named — the Apple client's
+                // `os present +N excluded` line, same wording so the two HUDs read alike.
+                // (This replaces the old "≈ Apple-HUD equiv" twin: both clients now shave, and
+                // Android's shave is measured rather than assumed at 2 refresh periods.)
+                if (floorMs > 0) {
                     statLine(
-                        "≈ Apple-HUD equiv: end-to-end " +
-                            "${"%.1f".format((s[24] - shave).coerceAtLeast(0.0))} · display " +
-                            "${"%.1f".format((s[23] - shave).coerceAtLeast(0.0))} (−2 refresh)",
-                        Color(0xFFA8D8B8),
+                        "os present +${"%.1f".format(floorMs)} excluded (display pipeline minimum)",
+                        Color(0xFF9AA6B8),
                     )
                 }
             }
@@ -167,6 +188,37 @@ private fun statLine(text: String, color: Color) {
     Text(text, color = color, fontFamily = FontFamily.Monospace, fontSize = 12.sp)
 }
 
+/**
+ * The OS present floor to exclude from the shown `display` / `end-to-end` numbers, ms — the
+ * measured `latch` p50 at index 27, i.e. release→`OnFrameRendered`: SurfaceFlinger's own latch and
+ * scanout. That is compositor pipeline depth no client can pace under, so it is reported as
+ * excluded rather than charged to Punktfunk — the Apple client's policy since its presentation
+ * rebuild, where the same floor is measured from the display link's vend lead.
+ *
+ * Measured, not assumed: the previous Android treatment used a fixed `2000/hz` twin, but the latch
+ * varies with panel rate, tunnelled playback and the vendor's low-latency mode (~21 ms p50 observed
+ * where the ~2-interval model predicts less), and this term self-adapts to all three. It is also
+ * available on every render path — the presenter's and both legacy release-immediately ones — since
+ * the release stamp it starts from is parked on every render, so it does not depend on
+ * `presenterActive` (29).
+ *
+ * `0.0` means unmeasured — no display stage this window (an older native lib, API < 33, or a
+ * platform that refused the callback), or no latch sample paired — and every caller then leaves its
+ * number raw, which is the honest fallback: we exclude only what we actually measured.
+ */
+private fun osFloorMs(s: DoubleArray): Double {
+    val dispValid = s.size >= 26 && s[22] != 0.0
+    if (!dispValid || s.size < 28) return 0.0
+    return s[27].coerceAtLeast(0.0)
+}
+
+/**
+ * Subtract the excluded [floorMs] from a shown latency [ms], clamped at zero — the percentiles are
+ * drawn from different sample sets (a p50 latch against a p50/p95 end-to-end), so the difference can
+ * legitimately go slightly negative on a well-paced window without anything being wrong.
+ */
+private fun shave(ms: Double, floorMs: Double): Double = (ms - floorMs).coerceAtLeast(0.0)
+
 /**
  * The single [StatsVerbosity.COMPACT] line: `238 fps · 1.3 ms · 921 Mb/s`. The end-to-end p50 term
  * is dropped when no in-range latency sample landed (`latValid` false), and a loss flag
@@ -174,8 +226,9 @@ private fun statLine(text: String, color: Color) {
  * one reliability signal worth surfacing even at the tersest tier.
  */
 private fun compactLine(s: DoubleArray, latValid: Boolean): String {
-    // Prefer the capture→displayed end-to-end (s[24]) when a render timestamp landed this window.
-    val e2eP50 = if (s.size >= 26 && s[22] != 0.0) s[24] else s[2]
+    // Prefer the capture→displayed end-to-end (s[24]) when a render timestamp landed this window,
+    // less the excluded OS present floor — the same number the richer tiers headline.
+    val e2eP50 = if (s.size >= 26 && s[22] != 0.0) shave(s[24], osFloorMs(s)) else s[2]
     val parts = buildList {
         add("${s[0].roundToInt()} fps")
         if (latValid) add("${"%.1f".format(e2eP50)} ms")

clients/android/app/src/test/kotlin/io/unom/punktfunk/screenshots/ShotScenes.kt

@@ -355,9 +355,11 @@ internal fun StreamScene(verbosity: StatsVerbosity = StatsVerbosity.DETAILED) {
         // dispValid, displayP50, e2eDispP50, e2eDispP95].
         // 10/9/16/1 = a 10-bit BT.2020 PQ (HDR) 4:2:0 feed so the DETAILED HUD renders its
         // video-feed line; the display stage is valid (dispValid 1) so the headline is the
-        // directly-measured capture→displayed pair (1.8/2.6) and the Phase-2 stage terms
-        // (host 0.6 + network 0.3 + decode 0.4 + display 0.5) tile it, rendering the full split
-        // equation; the decoder label shows the ranked low-latency decoder. Light per-window loss
+        // directly-measured capture→displayed pair, less the excluded OS present floor (the 0.3
+        // latch p50) — 1.5/2.3 shown from 1.8/2.6 raw — and the Phase-2 stage terms
+        // (host 0.6 + network 0.3 + decode 0.4 + display 0.2) tile the shaved headline, with the
+        // `os present +0.3 excluded` line naming what came off; the decoder label shows the ranked
+        // low-latency decoder. Light per-window loss
         // (lost 2 · skipped 1 · FEC 5 of 238) so the reliability line (NORMAL/DETAILED) and the
         // compact loss flag both render.
         StatsOverlay(

clients/android/native/src/decode/async_loop.rs

@@ -28,76 +28,6 @@ use super::{
     NO_VIDEO_RETRY, PENDING_SPLIT_CAP,
 };
 
-/// How long a flagged AU waits for the host's 0xCF timing before being logged unattributed.
-/// Comfortably longer than the round the host takes to report, short enough that the line still
-/// lands near the event in the log.
-const SPIKE_ATTRIBUTE_WAIT_NS: i64 = 500_000_000;
-
-/// Bound on AUs awaiting attribution — a stream that spikes constantly must not grow this.
-const SPIKE_WATCH_CAP: usize = 64;
-
-/// One receipt-latency excursion, held until the host's own timing for the same AU arrives.
-///
-/// The point of this record is attribution. A window maximum cannot say WHERE a 90 ms frame
-/// spent its time — the per-stage maxima in a window are generally different frames — so the
-/// stage split has to be captured per AU, for the offending AU.
-struct SpikeWatch {
-    pts_ns: u64,
-    /// Capture → reassembled, skew-corrected: the host pipeline plus the wire.
-    hostnet_us: u64,
-    au_len: usize,
-    /// Since the previous AU was reassembled — separates "this frame was slow" from "the
-    /// stream stalled and then burst", which look identical in a latency percentile.
-    gap_us: u64,
-    idx: u32,
-    seen_mono: i64,
-}
-
-impl SpikeWatch {
-    /// `host_us` = the host's own capture→submit time for this AU (0xCF), or `None` when the
-    /// host never reported it. `net` is the remainder: wire + reassembly.
-    fn log(&self, host_us: Option<u64>) {
-        log::warn!(
-            target: "pf.spike",
-            "idx={} hostnetMs={:.1} hostMs={} netMs={} gapMs={:.1} bytes={}",
-            self.idx,
-            self.hostnet_us as f64 / 1000.0,
-            host_us.map_or("?".into(), |h| format!("{:.1}", h as f64 / 1000.0)),
-            host_us.map_or("?".into(), |h| format!(
-                "{:.1}",
-                self.hostnet_us.saturating_sub(h) as f64 / 1000.0
-            )),
-            self.gap_us as f64 / 1000.0,
-            self.au_len,
-        );
-    }
-}
-
-/// `debug.punktfunk.spike_ms` (1..=2000): log a per-AU stage breakdown for every receipt latency
-/// at or above this. Unset = off, so the instrument costs nothing until someone asks for it.
-fn spike_threshold_us() -> Option<u64> {
-    let mut buf = [0u8; 92]; // PROP_VALUE_MAX
-                             // SAFETY: __system_property_get with a valid name + PROP_VALUE_MAX buffer is always safe.
-    let n = unsafe {
-        libc::__system_property_get(
-            c"debug.punktfunk.spike_ms".as_ptr(),
-            buf.as_mut_ptr().cast(),
-        )
-    };
-    if n > 0 {
-        if let Ok(ms) = std::str::from_utf8(&buf[..n as usize])
-            .unwrap_or("")
-            .trim()
-            .parse::<u64>()
-        {
-            if (1..=2_000).contains(&ms) {
-                return Some(ms * 1_000);
-            }
-        }
-    }
-    None
-}
-
 /// One decoded output buffer ready to release: its codec buffer index + the pts the codec echoed
 /// (from the output callback's `BufferInfo`), used to pair the `decode` HUD stat, and the
 /// wall-clock instant the output callback fired — the spec's `decoded` point ("decoder output
@@ -654,14 +584,6 @@ fn feeder_loop(
     // Last logged phase-lock ACK (the host's applied capture hold, from the 0xCF tail) — logged
     // on change so `adb logcat -s pf.phase` shows the closed loop working (or not) at a glance.
     let mut last_phase_ack: Option<i32> = None;
-    // Latency-excursion watch (`debug.punktfunk.spike_ms`). Read once per stream: this is a
-    // field instrument, armed by setprop + reconnect, and off by default.
-    let spike_thresh_us = spike_threshold_us();
-    if let Some(t) = spike_thresh_us {
-        log::info!("decode: spike watch armed at {} ms (pf.spike)", t / 1000);
-    }
-    let mut spike_watch: VecDeque<SpikeWatch> = VecDeque::new();
-    let mut last_recv_mono: Option<i64> = None;
     while !shutdown.load(Ordering::Relaxed) {
         match client.next_frame(Duration::from_millis(5)) {
             Ok(frame) => {
@@ -677,44 +599,6 @@ fn feeder_loop(
                 // Park the receipt stamp (keyed by the pts the codec echoes) whenever the `decode`
                 // stage is consumed: the HUD, or the ABR decode signal (`measure_decode`). The
                 // HUD-only `received` point + host/network split stay gated on the overlay.
-                // The receipt latency is needed by the always-on spike watch below, so it is
-                // computed for every complete AU rather than only when the HUD is up.
-                let spike_lat_us = if frame.complete {
-                    let received_ns = if frame.received_ns > 0 {
-                        frame.received_ns as i128
-                    } else {
-                        now_realtime_ns()
-                    };
-                    let off = clock_offset.load(Ordering::Relaxed) as i128;
-                    let lat_ns = received_ns + off - frame.pts_ns as i128;
-                    (lat_ns > 0 && lat_ns < 10_000_000_000).then_some((lat_ns / 1000) as u64)
-                } else {
-                    None
-                };
-                if let (Some(thresh_us), Some(lat_us)) = (spike_thresh_us, spike_lat_us) {
-                    let now_mono = now_monotonic_ns();
-                    let gap_us = last_recv_mono
-                        .map(|p| ((now_mono - p) / 1000) as u64)
-                        .unwrap_or(0);
-                    last_recv_mono = Some(now_mono);
-                    if lat_us >= thresh_us {
-                        let au_len = frame.part.map_or(0, |p| p.offset as usize) + frame.data.len();
-                        // Held for the host's 0xCF timing for this pts, which is what splits the
-                        // excursion into host pipeline vs wire — the whole point. Emitted
-                        // unattributed if that never arrives (see the drain below).
-                        spike_watch.push_back(SpikeWatch {
-                            pts_ns: frame.pts_ns,
-                            hostnet_us: lat_us,
-                            au_len,
-                            gap_us,
-                            idx: frame.frame_index,
-                            seen_mono: now_mono,
-                        });
-                        if spike_watch.len() > SPIKE_WATCH_CAP {
-                            spike_watch.pop_front();
-                        }
-                    }
-                }
                 if (stats.enabled() || measure_decode) && frame.complete {
                     // Core reassembly-completion stamp (ABI v9), NOT the pull instant: stamping
                     // here would fold the hand-off queue wait into the network latency figure
@@ -748,47 +632,28 @@ fn feeder_loop(
                                 pending_split.pop_front();
                             }
                         }
-                    }
-                }
-                // The 0xCF drain is OUTSIDE the HUD gate: it carries the host's own pipeline time
-                // per AU, which is what attributes a latency excursion to the host or the wire,
-                // and the phase-lock ack, which had no business being invisible with the HUD down.
-                while let Ok(t) = client.next_host_timing(Duration::ZERO) {
-                    // Phase-lock closed-loop readout: the host's applied hold rides the
-                    // 0xCF tail; log transitions (~1 Hz worst case — the host updates it
-                    // once a second). None = a host without the tail (pre-phase-lock).
-                    if t.applied_phase_ns != last_phase_ack {
-                        log::info!(
-                            target: "pf.phase",
-                            "host applied_phase={:?}us",
-                            t.applied_phase_ns.map(|n| n / 1000)
-                        );
-                        last_phase_ack = t.applied_phase_ns;
-                    }
-                    if stats.enabled() {
-                        if let Some(i) = pending_split.iter().position(|&(p, _)| p == t.pts_ns) {
-                            let (_, hostnet_us) = pending_split.remove(i).unwrap();
-                            stats.note_host_split(
-                                t.host_us as u64,
-                                hostnet_us.saturating_sub(t.host_us as u64),
-                            );
+                        while let Ok(t) = client.next_host_timing(Duration::ZERO) {
+                            // Phase-lock closed-loop readout: the host's applied hold rides the
+                            // 0xCF tail; log transitions (~1 Hz worst case — the host updates it
+                            // once a second). None = a host without the tail (pre-phase-lock).
+                            if t.applied_phase_ns != last_phase_ack {
+                                log::info!(
+                                    target: "pf.phase",
+                                    "host applied_phase={:?}us",
+                                    t.applied_phase_ns.map(|n| n / 1000)
+                                );
+                                last_phase_ack = t.applied_phase_ns;
+                            }
+                            if let Some(i) = pending_split.iter().position(|&(p, _)| p == t.pts_ns)
+                            {
+                                let (_, hostnet_us) = pending_split.remove(i).unwrap();
+                                stats.note_host_split(
+                                    t.host_us as u64,
+                                    hostnet_us.saturating_sub(t.host_us as u64),
+                                );
+                            }
                         }
                     }
-                    if let Some(i) = spike_watch.iter().position(|w| w.pts_ns == t.pts_ns) {
-                        let w = spike_watch.remove(i).unwrap();
-                        w.log(Some(t.host_us as u64));
-                    }
-                }
-                // Anything the host never reported on still gets logged, unattributed, rather
-                // than silently dropped — an old host has no 0xCF tail at all.
-                let now_mono = now_monotonic_ns();
-                while spike_watch
-                    .front()
-                    .is_some_and(|w| now_mono - w.seen_mono > SPIKE_ATTRIBUTE_WAIT_NS)
-                {
-                    if let Some(w) = spike_watch.pop_front() {
-                        w.log(None);
-                    }
                 }
                 if ev_tx.send(DecodeEvent::Au(frame, gap)).is_err() {
                     break; // the decode loop is gone

clients/android/native/src/decode/display.rs

@@ -185,7 +185,7 @@ unsafe extern "C" fn on_frame_rendered(
     let display_us = paired.and_then(|(d, _)| clamp(displayed_ns - d));
     let latch_us = paired.and_then(|(_, r)| clamp(displayed_ns - r));
     // Always-on half: the presenter's pf-present line reads these with the HUD off.
-    t.meter.note_latch(latch_us, system_nano);
+    t.meter.note_latch(latch_us);
     if !t.stats.enabled() {
         return; // HUD hidden — skip the skew math + the stats lock
     }

clients/android/native/src/decode/presenter.rs

@@ -22,7 +22,7 @@
 
 use ndk::media::media_codec::MediaCodec;
 use std::collections::VecDeque;
-use std::sync::atomic::{AtomicBool, AtomicI32, AtomicI64, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicI32, Ordering};
 use std::sync::Mutex;
 use std::time::Instant;
 
@@ -152,10 +152,6 @@ pub(super) struct PresentMeter {
     /// This device delivers render callbacks at all (API ≥ 33 and the platform accepted the
     /// registration). Until one arrives, `undisplayed` is meaningless and the rail stays down.
     confirms: AtomicBool,
-    /// The learned panel period the cadence statistic quantises against, republished by
-    /// [`Presenter::pump`] (the callback thread has no access to the vsync clock). 0 until the
-    /// grid is known, which simply means cadence is not scored yet.
-    panel_period_ns: AtomicI64,
 }
 
 struct PresentMeterInner {
@@ -170,9 +166,6 @@ struct PresentMeterInner {
     /// Capture→decoded end-to-end µs (skew-corrected, clamped) — always on for the same reason:
     /// the wireless A/B's headline without having to reach the on-screen HUD.
     e2e_us: Vec<u64>,
-    /// The cadence (judder) statistic — the only stat here that is not a latency, and the only
-    /// one that can see a pacing defect. See [`punktfunk_core::phase::PresentIntervals`].
-    intervals: punktfunk_core::phase::PresentIntervals,
 }
 
 impl PresentMeter {
@@ -184,33 +177,19 @@ impl PresentMeter {
                 feed_us: Vec::with_capacity(256),
                 codec_us: Vec::with_capacity(256),
                 e2e_us: Vec::with_capacity(256),
-                intervals: punktfunk_core::phase::PresentIntervals::new(),
             }),
             undisplayed: AtomicI32::new(0),
             confirms: AtomicBool::new(false),
-            panel_period_ns: AtomicI64::new(0),
         }
     }
 
-    /// Republish the learned panel period for the cadence statistic (presenter thread).
-    pub(super) fn set_panel_period(&self, period_ns: i64) {
-        self.panel_period_ns.store(period_ns, Ordering::Relaxed);
-    }
-
     /// One displayed frame's release→displayed latch, µs. Callback thread; poison-proof.
     ///
     /// Also the glass budget's CONFIRM: this frame left the BufferQueue, so one outstanding
     /// release is settled. Clamped at zero — the legacy `arrival` path renders without going
     /// through [`Presenter::pump`], so confirms can outnumber counted releases.
-    ///
-    /// `present_mono_ns` is SurfaceFlinger's own render timestamp, raw on `CLOCK_MONOTONIC` —
-    /// deliberately not the realtime-rebased instant the latency stats use. Cadence is a
-    /// statistic about *spacing*, and a realtime clock step (NTP) would forge a hitch that never
-    /// happened. Garbage stamps need no special handling here: an implausible one lands in the
-    /// stall or disordered counters rather than the judder ratio.
-    pub(super) fn note_latch(&self, latch_us: Option<u64>, present_mono_ns: i64) {
+    pub(super) fn note_latch(&self, latch_us: Option<u64>) {
         self.confirms.store(true, Ordering::Relaxed);
-        let period_ns = self.panel_period_ns.load(Ordering::Relaxed);
         let _ = self
             .undisplayed
             .fetch_update(Ordering::Relaxed, Ordering::Relaxed, |v| {
@@ -221,7 +200,6 @@ impl PresentMeter {
             .lock()
             .unwrap_or_else(std::sync::PoisonError::into_inner);
         g.displays += 1;
-        g.intervals.record(present_mono_ns, period_ns);
         if let Some(l) = latch_us {
             if g.latch_us.len() < 4096 {
                 g.latch_us.push(l);
@@ -280,17 +258,7 @@ impl PresentMeter {
     }
 
     #[allow(clippy::type_complexity)] // one caller unpacks it in place; a struct would be noise
-    fn drain(
-        &self,
-    ) -> (
-        Vec<u64>,
-        u64,
-        Vec<u64>,
-        Vec<u64>,
-        Vec<u64>,
-        (u32, u32, u32),
-        Option<punktfunk_core::phase::PresentCadence>,
-    ) {
+    fn drain(&self) -> (Vec<u64>, u64, Vec<u64>, Vec<u64>, Vec<u64>) {
         let mut g = self
             .inner
             .lock()
@@ -303,8 +271,6 @@ impl PresentMeter {
             std::mem::take(&mut g.feed_us),
             std::mem::take(&mut g.codec_us),
             std::mem::take(&mut g.e2e_us),
-            g.intervals.pending(),
-            g.intervals.take(),
         )
     }
 }
@@ -444,11 +410,6 @@ impl Presenter {
         stats: &crate::stats::VideoStats,
         now_mono_ns: i64,
     ) -> bool {
-        // The callback thread scores cadence but cannot see the vsync clock — republish the grid
-        // it quantises against. Relaxed: a period change is rare and one stale sample is noise.
-        if let Some(c) = clock {
-            meter.set_panel_period(c.panel_period_ns().max(c.period_ns()));
-        }
         // Budget bookkeeping first: reopen on the predicted latch, force-open on the backstop.
         if let Some(f) = &self.inflight {
             if now_mono_ns >= f.reopen_at_ns {
@@ -586,11 +547,7 @@ impl Presenter {
     /// `pace` (decoded→release) / `latch` (release→displayed) /
     /// `feed`+`codec` (the decode stage split: received→queued hand-off/slot wait + the
     /// codec-pure queued→decoded time) / `e2e` (capture→decoded, skew-corrected — the wireless
-    /// A/B headline) / `vsync` (the measured panel period) /
-    /// `judder` (‰ of present intervals off the modal spacing — the cadence statistic, and the
-    /// only number here that can see a pacing defect) / `mode` (the modal spacing in refreshes:
-    /// 1 at panel rate, 2 for 60-on-120) / `stalls` + `disorder` (excluded from the ratio; see
-    /// [`punktfunk_core::phase::PresentIntervals`]).
+    /// A/B headline) / `vsync` (the measured panel period).
     ///
     /// Returns this window's CIRCULAR latch statistics `(vector-mean latch ns mod panel period,
     /// coherence ‰)` when a window actually flushed — the phase-lock reporter's v2 error signal
@@ -604,7 +561,7 @@ impl Presenter {
             return None;
         }
         self.last_flush = Instant::now();
-        let (latch, displays, feed, codec, e2e, cad_raw, cadence) = meter.drain();
+        let (latch, displays, feed, codec, e2e) = meter.drain();
         if self.released == 0 && displays == 0 {
             return None; // idle stream — nothing worth a line
         }
@@ -627,8 +584,7 @@ impl Presenter {
              paceMs p50={:.2} max={:.2} latchMs p50={:.2} max={:.2} \
              feedMs p50={:.2} max={:.2} codecMs p50={:.2} max={:.2} \
              e2eMs p50={:.2} max={:.2} circ={:.2}ms coh={} \
-             vsyncMs={:.2} panelMs={:.2} \
-             judder={}permille mode={}vsync cadN={} stalls={} disorder={} cadPeriodMs={:.2}",
+             vsyncMs={:.2} panelMs={:.2}",
             self.released,
             displays,
             self.paced_drops,
@@ -651,12 +607,6 @@ impl Presenter {
             circ.map(|(_, c)| c).unwrap_or(0),
             period_ms,
             panel_ns as f64 / 1e6,
-            cadence.map(|c| c.judder_permille).unwrap_or(0),
-            cadence.map(|c| c.mode_units).unwrap_or(0),
-            cad_raw.0,
-            cad_raw.1,
-            cad_raw.2,
-            meter.panel_period_ns.load(Ordering::Relaxed) as f64 / 1e6,
         );
         self.released = 0;
         // Margin adaptation, off the MEASURED latch. A release targets the first grid point past

clients/apple/Sources/PunktfunkKit/Video/Stage2Pipeline.swift

@@ -474,7 +474,6 @@ private final class DeadlineLinkDelegate: NSObject, CAMetalDisplayLinkDelegate {
         // The link's own pipeline depth, measured: how far ahead of glass this vend runs.
         let leadS = update.targetPresentationTimestamp - CACurrentMediaTime()
         stats?.vendLead(ms: leadS * 1000)
-        stats?.notePanelTarget(mediaTime: update.targetPresentationTimestamp)
         // Same measurement into the floor meter (as a LatencyMeter sample: end = now, start =
         // now − lead) — its 1 s p50 is the OS present floor SessionModel shaves off.
         if leadS > 0, let floorMeter {
@@ -563,112 +562,6 @@ final class PresentGate: @unchecked Sendable {
     }
 }
 
-/// One window's present-cadence summary (see `PresentIntervals`).
-struct PresentCadence: Equatable {
-    /// The most common spacing, in whole panel refreshes: 1 at panel rate, 2 for 60-on-120.
-    let modeUnits: Int
-    /// Fraction of intervals that were NOT the mode, in ‰. **The judder number.**
-    let judderPermille: Int
-    let samples: Int
-    /// Spacings wider than `maxUnits` — stalls, not judder.
-    let stalls: Int
-    /// Present instants that did not advance (duplicate/out-of-order callbacks).
-    let disordered: Int
-}
-
-/// Present-interval distribution in whole panel refreshes — the cadence (judder) statistic.
-///
-/// A **verbatim port of `punktfunk_core::phase::PresentIntervals`**, in the same spirit as
-/// `PhaseReporter.circularLatch` above: the three clients must publish the SAME statistic, so the
-/// numbers can be compared across platforms and so a feature-on/off A/B uses one ruler. Any change
-/// here belongs in the Rust original first — including the tie-break, which is spelled out on both
-/// sides precisely because the two languages' `max` disagree about which equal element wins.
-///
-/// Every other stat we publish is a latency: a difference between two points on one frame. No
-/// latency can see judder, because judder is a property of the *sequence*. A stream that shows each
-/// frame one refresh early and the next one late has excellent percentiles and looks broken.
-///
-/// Fed the MEASURED on-glass instant, never the requested present time — the latter would measure
-/// our own intent and report a perfect cadence no matter what the display did.
-struct PresentIntervals {
-    /// Largest spacing still treated as cadence; wider is a stall, counted apart.
-    private static let maxUnits = 8
-    /// Minimum intervals before a summary means anything (matches `circularLatch`'s bar).
-    private static let minSamples = 8
-    /// A backwards step larger than this is a bogus timestamp, not a reordered delivery, so the
-    /// run re-anchors rather than holding the old instant. Without it, one garbage far-future
-    /// stamp latches the statistic and every later present scores as disordered for the whole
-    /// session — observed on glass on Android, 2026-08-05.
-    private static let reanchorNs: Int64 = 100_000_000
-
-    private var lastPresentNs: Int64 = 0
-    private var hist = [Int](repeating: 0, count: PresentIntervals.maxUnits + 1)
-    private var samples = 0
-    private var stalls = 0
-    private var disordered = 0
-
-    /// Forget the previous instant without discarding the window's counts — a discontinuity where
-    /// the next present does not continue this cadence.
-    mutating func split() { lastPresentNs = 0 }
-
-    /// Fold one on-glass instant. A non-positive `periodNs` means the grid is not known yet and
-    /// the sample is held as the new predecessor without being scored.
-    mutating func record(presentNs: Int64, periodNs: Int64) {
-        let prev = lastPresentNs
-        lastPresentNs = presentNs
-        guard prev > 0, periodNs > 0 else { return }
-        let spacing = presentNs - prev
-        if spacing <= 0 {
-            // Hold the LATER instant so one reordered delivery cannot corrupt every following
-            // spacing — but only when the step back is small enough to BE a reordering. Beyond
-            // that the old instant is the bogus one (see `reanchorNs`) and the run re-anchors
-            // onto the new sample, which `lastPresentNs` already holds.
-            disordered += 1
-            if prev - presentNs < PresentIntervals.reanchorNs {
-                lastPresentNs = prev
-            }
-            return
-        }
-        // Nearest whole refresh: a present is "on the grid" if it is closer to this vblank than
-        // the next, which is exactly what the display did with it.
-        let units = Int((spacing * 2 + periodNs) / (periodNs * 2))
-        if units > PresentIntervals.maxUnits {
-            stalls += 1
-            return
-        }
-        hist[units] += 1
-        samples += 1
-    }
-
-    /// This window's summary, or nil under `minSamples`.
-    func summary() -> PresentCadence? {
-        guard samples >= PresentIntervals.minSamples else { return nil }
-        // Ties resolve to the SMALLEST spacing — see the Rust original: `max_by_key` takes the
-        // last maximum and Swift's `max(by:)` the first, so this is written out on both sides.
-        var modeUnits = 0
-        var modeCount = 0
-        for (i, c) in hist.enumerated() where c > modeCount {
-            modeCount = c
-            modeUnits = i
-        }
-        return PresentCadence(
-            modeUnits: modeUnits,
-            judderPermille: (samples - modeCount) * 1000 / samples,
-            samples: samples, stalls: stalls, disordered: disordered)
-    }
-
-    /// Drain the window. The previous instant SURVIVES — the cadence continues across a window
-    /// boundary, and dropping it would manufacture one unscored interval per window.
-    mutating func take() -> PresentCadence? {
-        let out = summary()
-        hist = [Int](repeating: 0, count: PresentIntervals.maxUnits + 1)
-        samples = 0
-        stalls = 0
-        disordered = 0
-        return out
-    }
-}
-
 /// PUNKTFUNK_PRESENT_DEBUG=1 aggregation: one printed line per second from the render thread with
 /// the decode rate, render outcomes, the slowest render call (≈ nextDrawable wait) and the deltas
 /// between system-reported on-glass times (vsync-aligned presents show clean refresh-period
@@ -695,50 +588,6 @@ private final class PresentDebugStats: @unchecked Sendable {
     /// 120 Hz panel saturates this at ~maximumDrawableCount; stage-3 pegs it at the gate depth).
     private var inFlight = 0
     private var maxInFlight = 0
-    /// The cadence (judder) statistic — the only number here that is not a latency, and the only
-    /// one that can see a pacing defect. `glassDeltasMs` above is the same raw material reported
-    /// as a percentile, which cannot distinguish a steady 2-refresh cadence from an alternating
-    /// 1-and-3 one: same mean, same median, one of them visibly broken.
-    private var intervals = PresentIntervals()
-    /// The panel period cadence quantises against: seeded from the display mode and refined from
-    /// the link's own reported period, mirroring `punktfunk_core::phase::PanelGrid`'s seed-then-
-    /// correct design. 0 until known, which simply means cadence is not scored yet.
-    private var panelPeriodNs: Int64 = 0
-    /// Deadline-pacing period learner state (see `notePanelTarget`). Re-armed each window so a
-    /// mode or VRR rate change is tracked both ways rather than latching the first value seen.
-    private var lastTargetS: CFTimeInterval = 0
-    private var minTargetSpacingS: CFTimeInterval = 0
-    /// Whether the verbose per-second line prints. The cadence line always does: a smoothness
-    /// defect must not be invisible until someone thinks to set an env var.
-    private let verbose: Bool
-
-    init(verbose: Bool) { self.verbose = verbose }
-
-    /// Seed or refine the panel period (render/link thread).
-    func setPanelPeriod(ns: Int64) {
-        guard ns > 0 else { return }
-        lock.lock()
-        panelPeriodNs = ns
-        lock.unlock()
-    }
-
-    /// Deadline pacing has no reported period, so learn it from the link's own target instants.
-    /// Those tick at the panel rate whether or not WE present, which is what makes the window
-    /// minimum the true period — the same reasoning (and the same guard band) `PhaseReporter`
-    /// uses above. Learning it from on-glass spacings instead would read a 60-on-120 stream as a
-    /// 60 Hz panel and mislabel the cadence mode.
-    func notePanelTarget(mediaTime t: CFTimeInterval) {
-        lock.lock()
-        defer { lock.unlock() }
-        defer { lastTargetS = t }
-        guard lastTargetS > 0 else { return }
-        let d = t - lastTargetS
-        guard d > 0.0005, d < 0.1 else { return }
-        if minTargetSpacingS == 0 || d < minTargetSpacingS {
-            minTargetSpacingS = d
-            panelPeriodNs = Int64(d * 1_000_000_000)
-        }
-    }
 
     func emptyWake() { lock.lock(); empty += 1; lock.unlock() }
 
@@ -775,13 +624,8 @@ private final class PresentDebugStats: @unchecked Sendable {
             if lastGlassNs > 0 { glassDeltasMs.append(Double(atNs - lastGlassNs) / 1e6) }
             lastGlassNs = atNs
             latchMs.append(Double(atNs - issuedNs) / 1e6)
-            intervals.record(presentNs: atNs, periodNs: panelPeriodNs)
         } else {
-            // A dropped drawable never reached glass, so it is not a cadence event — but the
-            // NEXT one does not continue the previous interval either. Split rather than let
-            // the gap read as judder.
             dropped += 1
-            intervals.split()
         }
         lock.unlock()
     }
@@ -812,9 +656,6 @@ private final class PresentDebugStats: @unchecked Sendable {
             smoothing.overflowDrops, smoothing.underflows, maxRenderMs, inflightMax,
             gate?.drainForced() ?? 0, p50, dMax, deltas.count, latchP50, latchMax,
             vendP50, vendMax)
-        let cadence = intervals.take()
-        let verbose = self.verbose
-        minTargetSpacingS = 0 // re-arm the period learner for the next window
         ok = 0; failed = 0; empty = 0; dropped = 0; gated = 0; noDrawable = 0
         maxRenderMs = 0
         maxInFlight = inFlight // the window peak restarts from the live depth
@@ -822,21 +663,6 @@ private final class PresentDebugStats: @unchecked Sendable {
         latchMs.removeAll(keepingCapacity: true)
         vendLeadMs.removeAll(keepingCapacity: true)
         lock.unlock()
-        // The cadence line is ALWAYS emitted (when the window had evidence): it is the ruler the
-        // smoothness A/B reads, and it must not depend on an env var the field never sets. The
-        // verbose counters line stays behind its existing lever.
-        if let cadence {
-            let cadenceLine = String(
-                format: "pf-present judderPermille=%d modeVsync=%d n=%d stalls=%d disorder=%d",
-                cadence.judderPermille, cadence.modeUnits, cadence.samples,
-                cadence.stalls, cadence.disordered)
-            presentLog.info("\(cadenceLine, privacy: .public)")
-            if presentDebug {
-                print(cadenceLine)
-                fflush(stdout)
-            }
-        }
-        guard verbose else { return }
         // Console.app first (the on-device readout — see presentLog); stdout only under the env
         // lever (the CLI client's capture channel).
         presentLog.info("\(line, privacy: .public)")
@@ -920,10 +746,6 @@ public final class Stage2Pipeline {
     /// mirror the pump's bounded join.
     private let renderSignal = DispatchSemaphore(value: 0)
     private let vsyncClock = VsyncClock()
-    /// The per-session present statistics, retained so the clock-bearing threads can republish
-    /// the panel period the cadence statistic quantises against. Assigned once in `start`, read
-    /// from the render/link threads; the object is itself lock-guarded.
-    private var presentStats: PresentDebugStats?
     private let renderStopped = DispatchSemaphore(value: 0)
     private var renderJoinable = false
     /// Deadline pacing's staged CAMetalDisplayLink frame-rate hint (see `FrameRateHint`).
@@ -1145,14 +967,7 @@ public final class Stage2Pipeline {
         // startDeadlinePresenter. The V-Sync policy below doesn't apply there (the link deadline-
         // times every present). Deadline sessions ALWAYS carry the stats (their pf-present line
         // streams to Console.app via presentLog — the on-device pacing decomposition).
-        //
-        // The stats object is now built for EVERY session, because the cadence statistic inside
-        // it has to be: a smoothness defect produces no drops and healthy percentiles, so gating
-        // it behind an env var means the one number that could see it is off exactly when it
-        // matters. `verbose` preserves the old behaviour for the wordy counters line.
-        let debugStats: PresentDebugStats? = PresentDebugStats(
-            verbose: presentDebug || pacing == .deadline)
-        presentStats = debugStats
+        let debugStats = (presentDebug || pacing == .deadline) ? PresentDebugStats() : nil
         if pacing == .deadline {
             startDeadlinePresenter(debugStats: debugStats)
             return
@@ -1426,9 +1241,6 @@ public final class Stage2Pipeline {
     /// (their CAMetalDisplayLink's updates are both clock and retry).
     public func renderTick(targetMediaTime: CFTimeInterval, period: CFTimeInterval) {
         vsyncClock.set(target: targetMediaTime, period: period)
-        // The link's own reported period is the authoritative grid for the cadence statistic —
-        // it tracks VRR rate changes, which a mode-derived seed cannot.
-        presentStats?.setPanelPeriod(ns: Int64(period * 1_000_000_000))
         renderSignal.signal()
     }
 

clients/apple/Tests/PunktfunkKitTests/PresentIntervalsTests.swift

@@ -1,170 +0,0 @@
-// Parity tests for the Swift `PresentIntervals` port (Video/Stage2Pipeline.swift) against
-// `punktfunk_core::phase::PresentIntervals` — the cadence (judder) statistic of
-// design/presenter-cadence-rework.md WP1.
-//
-// These are deliberately the SAME cases and the SAME vectors as the Rust unit tests in
-// crates/punktfunk-core/src/phase.rs (module `cadence_tests`). WP1's acceptance criterion is that
-// all three clients emit the same numbers for the same synthetic input, and a hand-written port is
-// exactly where that quietly stops being true — so the port is pinned here rather than trusted.
-//
-// If you change one side, change both, and keep the vectors identical.
-
-import Foundation
-import XCTest
-
-@testable import PunktfunkKit
-
-final class PresentIntervalsTests: XCTestCase {
-    /// 120 Hz in ns — the Rust tests' `P`.
-    private static let P: Int64 = 8_333_333
-
-    /// Fold `n` presents spaced by `spacings` in rotation, starting at an arbitrary instant.
-    /// Mirrors the Rust helper of the same shape.
-    private func cadence(_ spacings: [Int64], _ n: Int, period: Int64 = P) -> PresentIntervals {
-        var pi = PresentIntervals()
-        var t: Int64 = 1_000_000_000
-        pi.record(presentNs: t, periodNs: period)
-        for i in 0..<n {
-            t += spacings[i % spacings.count]
-            pi.record(presentNs: t, periodNs: period)
-        }
-        return pi
-    }
-
-    func testARegularCadenceHasNoJudder() {
-        let s = cadence([Self.P], 60).summary()
-        XCTAssertEqual(s?.modeUnits, 1)
-        XCTAssertEqual(s?.judderPermille, 0)
-        XCTAssertEqual(s?.samples, 60)
-    }
-
-    /// The property that makes this one ruler across rates: a stream at half (or a quarter of)
-    /// the panel rate is SMOOTH, not judder — the mode absorbs the cadence ratio.
-    func testSixtyOnOneTwentyReadsSmooth() {
-        for (mult, expected) in [(Int64(2), 2), (Int64(4), 4)] {
-            let s = cadence([Self.P * mult], 40).summary()
-            XCTAssertEqual(s?.modeUnits, expected)
-            XCTAssertEqual(s?.judderPermille, 0)
-        }
-    }
-
-    /// D3's signature: the same mean spacing as a steady 2, delivered as alternating 1 and 3.
-    /// Identical average frame rate, identical latency percentiles — this is the broken-looking one.
-    ///
-    /// Also pins the TIE-BREAK. The histogram is 50/50 here, and Rust's `max_by_key` takes the
-    /// last maximum while Swift's `max(by:)` takes the first, so both sides spell the rule out:
-    /// ties resolve to the smallest spacing.
-    func testTheSawtoothThatLatencyStatsCannotSee() {
-        let s = cadence([Self.P, Self.P * 3], 40).summary()
-        XCTAssertEqual(s?.judderPermille, 500)
-        XCTAssertEqual(s?.modeUnits, 1, "a tied mode resolves to the smallest spacing")
-    }
-
-    /// Sub-refresh jitter is not judder: the display quantises it away, so the metric must too.
-    func testJitterInsideARefreshIsNotJudder() {
-        let s = cadence([Self.P + Self.P * 2 / 5, Self.P - Self.P * 2 / 5], 40).summary()
-        XCTAssertEqual(s?.modeUnits, 1)
-        XCTAssertEqual(s?.judderPermille, 0)
-    }
-
-    func testAStallIsCountedApartFromJudder() {
-        var pi = PresentIntervals()
-        var t: Int64 = 1_000_000_000
-        pi.record(presentNs: t, periodNs: Self.P)
-        for _ in 0..<20 {
-            t += Self.P
-            pi.record(presentNs: t, periodNs: Self.P)
-        }
-        t += Self.P * 400  // a pause, not a pacing defect
-        pi.record(presentNs: t, periodNs: Self.P)
-        let s = pi.summary()
-        XCTAssertEqual(s?.judderPermille, 0)
-        XCTAssertEqual(s?.stalls, 1)
-        XCTAssertEqual(s?.samples, 20)
-    }
-
-    func testOutOfOrderCallbacksDoNotCorruptTheRun() {
-        var pi = PresentIntervals()
-        var t: Int64 = 1_000_000_000
-        pi.record(presentNs: t, periodNs: Self.P)
-        for _ in 0..<10 {
-            t += Self.P
-            pi.record(presentNs: t, periodNs: Self.P)
-        }
-        pi.record(presentNs: t - Self.P * 3, periodNs: Self.P)  // a late/duplicate delivery
-        for _ in 0..<10 {
-            t += Self.P
-            pi.record(presentNs: t, periodNs: Self.P)
-        }
-        let s = pi.summary()
-        XCTAssertEqual(s?.disordered, 1)
-        XCTAssertEqual(
-            s?.judderPermille, 0,
-            "keeping the later instant means the following spacings stay on the grid")
-    }
-
-    /// The on-glass failure of 2026-08-05, pinned on both sides. A render callback can deliver a
-    /// garbage far-future timestamp on a session's first frames; holding "the later instant"
-    /// unconditionally latched onto it and scored EVERY subsequent present as disordered for the
-    /// whole session. One bad sample must cost one sample.
-    func testAGarbageFarFutureStampDoesNotWedgeTheRun() {
-        var pi = PresentIntervals()
-        var t: Int64 = 1_000_000_000
-        pi.record(presentNs: t, periodNs: Self.P)
-        pi.record(presentNs: t + 60 * 60 * 1_000_000_000, periodNs: Self.P)
-        for _ in 0..<20 {
-            t += Self.P
-            pi.record(presentNs: t, periodNs: Self.P)
-        }
-        let s = pi.summary()
-        XCTAssertEqual(s?.disordered, 1, "the garbage stamp cost exactly one sample")
-        XCTAssertEqual(s?.modeUnits, 1)
-        XCTAssertEqual(s?.judderPermille, 0)
-        XCTAssertEqual(s?.samples, 19, "every present after the re-anchor scored")
-    }
-
-    func testAnUnknownGridScoresNothing() {
-        var pi = PresentIntervals()
-        var t: Int64 = 1_000_000_000
-        for _ in 0..<60 {
-            t += Self.P
-            pi.record(presentNs: t, periodNs: 0)  // no learned period yet
-        }
-        XCTAssertNil(pi.summary())
-        XCTAssertNotNil(cadence([Self.P], 60).summary(), "control")
-    }
-
-    func testAShortWindowPublishesNothing() {
-        XCTAssertNil(cadence([Self.P], 5).summary())
-    }
-
-    /// The cadence continues across a window boundary — dropping the predecessor on drain would
-    /// silently discard one interval per window, every window.
-    func testTakeResetsTheCountsButNotTheCadence() {
-        var pi = cadence([Self.P], 20)
-        XCTAssertNotNil(pi.take())
-        XCTAssertNil(pi.summary(), "counts cleared")
-        var t: Int64 = 1_000_000_000 + Self.P * 20
-        for _ in 0..<10 {
-            t += Self.P
-            pi.record(presentNs: t, periodNs: Self.P)
-        }
-        XCTAssertEqual(
-            pi.summary()?.samples, 10,
-            "the first post-drain present scored against the pre-drain one")
-    }
-
-    func testSplitForgetsThePredecessor() {
-        var pi = cadence([Self.P], 20)
-        _ = pi.take()
-        pi.split()
-        var t: Int64 = 5_000_000_000  // a discontinuity: the gap across it is meaningless
-        for _ in 0..<10 {
-            t += Self.P
-            pi.record(presentNs: t, periodNs: Self.P)
-        }
-        let s = pi.summary()
-        XCTAssertEqual(s?.samples, 9)
-        XCTAssertEqual(s?.stalls, 0, "the gap was not scored at all")
-    }
-}

clients/decky/plugin.json

@@ -1,5 +1,5 @@
 {
-  "name": "punktfunk",
+  "name": "Punktfunk",
   "author": "enrico",
   "flags": ["debug"],
   "api_version": 1,

clients/decky/scripts/deploy.sh

@@ -12,7 +12,9 @@
 set -euo pipefail
 HERE="$(cd "$(dirname "$0")/.." && pwd)"
 DECK="${DECK:?set DECK=deck@<ip>}"
-NAME="$(python3 -c 'import json;print(json.load(open("'"$HERE"'/plugin.json"))["name"])')"
+# The on-disk plugin DIR (what scripts/package.sh staged into out/), not plugin.json "name" —
+# that field is the brand-cased label Decky shows in its plugin list. See package.sh's header.
+NAME=punktfunk
 STAGE_LOCAL="$HERE/out/$NAME"
 [ -d "$STAGE_LOCAL" ] || { echo "$STAGE_LOCAL missing — run scripts/package.sh first" >&2; exit 1; }
 

clients/decky/scripts/package.sh

@@ -5,9 +5,13 @@
 #                                                  package.json,decky.pyi,LICENSE,README.md}
 #   out/punktfunk/                 (the same tree, unzipped — rsync this with scripts/deploy.sh)
 #
-# Decky extracts the zip with --strip-components=1, so the single top-level dir MUST equal
-# plugin.json "name". Run after `pnpm build` (or use `pnpm run package`). Host-agnostic: needs
-# only bash, python3 and zip.
+# The single top-level dir is the plugin's ON-DISK folder name (Decky extracts the zip as-is,
+# so the dir in the zip becomes ~/homebrew/plugins/<dir>). It is deliberately NOT read from
+# plugin.json "name": that field is the user-visible label ("Punktfunk", brand-cased, shown in
+# Decky's plugin list) and Decky locates an installed plugin by MATCHING it, never by the folder
+# name. Keeping the folder lowercase means a rename of the label can't strand the old directory
+# next to a new one (which would show up as two plugins).
+# Run after `pnpm build` (or use `pnpm run package`). Host-agnostic: needs only bash, python3 and zip.
 set -euo pipefail
 HERE="$(cd "$(dirname "$0")/.." && pwd)"
 cd "$HERE"
@@ -15,7 +19,7 @@ cd "$HERE"
 [ -f dist/index.js ] || { echo "dist/index.js missing — run 'pnpm build' first" >&2; exit 1; }
 [ -f LICENSE ]       || { echo "LICENSE missing (required by the Decky store)" >&2; exit 1; }
 
-NAME="$(python3 -c 'import json;print(json.load(open("plugin.json"))["name"])')"
+NAME=punktfunk   # the on-disk plugin dir (see the header) — NOT plugin.json "name"
 VER="$(python3 -c 'import json;print(json.load(open("package.json"))["version"])')"
 
 STAGE="$(mktemp -d)"

clients/decky/src/hooks.ts

@@ -122,6 +122,25 @@ function advertMatchesSaved(a: DiscoveredHost, s: SavedHost): boolean {
   );
 }
 
+/**
+ * The label a saved row shows.
+ *
+ * A saved record whose name IS its own address is a PLACEHOLDER, not a choice: `hosts add`
+ * falls back to the address when the pairing path had nothing better, so the row ends up
+ * captioned with the same string it already prints underneath. When the box is on the air it
+ * is advertising its actual hostname — prefer that, and the row reads "home-worker-5" instead
+ * of "192.168.1.21".
+ *
+ * A real saved name always wins over the advert, even a stale one: it may be a name the user
+ * chose, and a live advert must never quietly overwrite that. Compared against the SAVED
+ * address, so a host that moved DHCP lease still recognises its old address as a placeholder.
+ */
+function hostLabel(s: SavedHost, advert?: DiscoveredHost): string {
+  const placeholder = !s.name || s.name === s.addr || s.name === `${s.addr}:${s.port}`;
+  if (!placeholder) return s.name;
+  return advert?.name || s.name || s.addr;
+}
+
 /**
  * Join the saved store and the live browse into the rows the panel draws.
  *
@@ -134,7 +153,7 @@ export function mergeHosts(saved: SavedHost[], discovered: DiscoveredHost[]): Ho
     // Prefer a live advert's address: the host may have moved since it was last saved.
     const advert = discovered.find((a) => advertMatchesSaved(a, s));
     return {
-      name: s.name || s.addr,
+      name: hostLabel(s, advert),
       addr: advert?.addr ?? s.addr,
       port: advert?.port ?? s.port,
       fp: s.fp_hex,
@@ -387,7 +406,10 @@ export async function applyUpdate(
         // before any result could arrive — so never await it. Decky shows its own confirm prompt.
         void backend.callable("utilities/install_plugin")(
           info.artifact,
-          "punktfunk",
+          // The name Decky uninstalls before extracting the new zip — it locates the folder by
+          // matching plugin.json "name", so this must equal THIS build's plugin.json name (the
+          // brand-cased one), not the lowercase on-disk dir.
+          "Punktfunk",
           info.latest,
           info.hash,
           INSTALL_TYPE_UPDATE,

clients/decky/src/index.tsx

@@ -337,9 +337,11 @@ export default definePlugin(() => {
   // controller config. Fire-and-forget: cosmetic library upkeep must never block plugin load.
   void ensureGamepadUiShortcut();
   return {
-    // `name` is the plugin's INTERNAL id — it must stay in sync with plugin.json (the loader
-    // keys plugins by it), so it stays lowercase; user-facing strings say "Punktfunk".
-    name: "punktfunk",
+    // `name` must stay in sync with plugin.json (the loader keys plugins by it) — and it is
+    // USER-VISIBLE: Decky labels the entry in its plugin list with it, so it carries the brand
+    // case. Decky finds an installed plugin by matching plugin.json "name" (never the folder
+    // name), so this is independent of the on-disk dir, which stays lowercase `punktfunk`.
+    name: "Punktfunk",
     // `staticClasses?.Title` is guarded so a future client that drops the export can't throw
     // at plugin-load time (an error boundary only catches render-time, not load-time, errors).
     titleView: <div className={staticClasses?.Title}>Punktfunk</div>,

clients/decky/src/steam.ts

@@ -70,9 +70,18 @@ declare const appStore:
  *  entry from a false "missing". A confident null means the shortcut was deleted → recreate. */
 function shortcutStillExists(appId: number): boolean {
   try {
-    const get = appStore?.GetAppOverviewByAppID;
-    if (!get) return true; // no way to verify — preserve the reuse path
-    return get(appId) != null;
+    // Call it as a METHOD on appStore — NEVER as an extracted function. Its implementation
+    // reads the store's own state (`this.m_mapApps`), so `const get = appStore.GetAppOverview…;
+    // get(id)` throws on the lost `this`, and the catch below turns that into a permanent
+    // "true". That is not a stale-data bug but a total one: the guard then answers "still
+    // exists" for EVERY appId, so a dangling id is never dropped, the reuse path repoints a
+    // dead shortcut (silent no-ops), and "recreate" reports success having done nothing.
+    // `typeof` first: `appStore` is a Steam-injected global, and a bare reference to a missing
+    // one is a ReferenceError that optional chaining does NOT prevent.
+    if (typeof appStore === "undefined" || !appStore?.GetAppOverviewByAppID) {
+      return true; // no way to verify — preserve the reuse path
+    }
+    return appStore.GetAppOverviewByAppID(appId) != null;
   } catch {
     return true;
   }

clients/linux/src/cli.rs

@@ -773,6 +773,7 @@ fn mock_library() -> (
         title: title.to_string(),
         art: crate::library::Artwork::default(),
         platform: None,
+        role: None,
     };
     let games = vec![
         game("steam:570", "steam", "Dota 2"),

clients/windows/src/app/settings.rs

@@ -1911,10 +1911,35 @@ pub(crate) fn settings_page(
     } else {
         border(vstack(Vec::<Element>::new())).into()
     };
+    // Every save on this page is fire-and-forget by design — a failed settings write must
+    // never take a stream down — so a client whose config store rejects writes looks entirely
+    // normal: toggles move, profiles appear, and NOTHING survives a restart. That is exactly
+    // how it reached us from the field ("it's in read-only mode"), with no log file to send
+    // either. When the store is refusing writes, say so, name the path, and stop pretending.
+    //
+    // Same always-mounted-slot discipline as `sheet_slot`: one child in both states, and the
+    // SAME KIND in both (a Border wrapping the bar, versus an empty background-less Border —
+    // which per style.rs is not hit-testable, so it swallows no clicks). Neither a grid child
+    // nor a vstack child is ever added or removed, which is where this reconciler's phantom
+    // bookkeeping breaks.
+    let store_slot: Element = match pf_client_core::trust::store_health::last_error() {
+        Some(err) => border(
+            InfoBar::new("Your changes aren\u{2019}t being saved")
+                .message(format!(
+                    "Punktfunk can\u{2019}t write to its settings folder, so nothing on this \
+                     page will survive a restart. {err}"
+                ))
+                .error()
+                .is_closable(false),
+        )
+        .margin(edges(24.0, 12.0, 28.0, 0.0))
+        .into(),
+        None => border(vstack(Vec::<Element>::new())).into(),
+    };
     // The bar rides an Auto row above the nav's Star row, so the nav (and the sheet's scrim
     // over it) still fills the rest of the window.
     grid(vec![
-        scope_bar.grid_row(0),
+        Element::from(vstack(vec![store_slot, scope_bar])).grid_row(0),
         Element::from(grid(vec![nav.into(), sheet_slot, confirm])).grid_row(1),
     ])
     .rows([GridLength::Auto, GridLength::STAR])

crates/pf-client-core/src/library.rs

@@ -66,6 +66,20 @@ pub struct GameEntry {
     /// host's flattened `GameMeta`; the rest of the metadata is not decoded until a UI needs it.
     #[serde(default)]
     pub platform: Option<String>,
+    /// `"game"` (the default, and what an older host omits) or `"launcher"` — an entry that opens
+    /// the launcher itself (Steam Big Picture, Heroic) rather than a title. A UI may group these
+    /// separately; one that doesn't renders them as ordinary tiles, which is the intended
+    /// degradation (design D4). Kept a plain string: the host owns the vocabulary, and an unknown
+    /// future value must never fail the whole library decode.
+    #[serde(default)]
+    pub role: Option<String>,
+}
+
+impl GameEntry {
+    /// Whether this entry opens a launcher rather than a game.
+    pub fn is_launcher(&self) -> bool {
+        self.role.as_deref() == Some("launcher")
+    }
 }
 
 /// Errors surfaced to the UI so it can guide setup (the common case is "not paired yet").

crates/pf-client-core/src/trust.rs

@@ -91,22 +91,131 @@ fn lock_identity_perms(dir: &std::path::Path, key: &std::path::Path) {
     let _ = std::fs::set_permissions(key, std::fs::Permissions::from_mode(0o600));
 }
 
+/// A sibling temp path unique to this process. The stores below have five whole-file writers
+/// (WinUI shell, session, console UI, CLI, Decky) and a single shared `.json.tmp` lets two of
+/// them interleave: on Windows the second `fs::write` hits a sharing violation, and worse, one
+/// process can rename the OTHER's half-written bytes over the target. The pid keeps each
+/// writer on its own scratch file; the rename below removes it, so a leftover only survives a
+/// hard kill.
+fn temp_sibling(path: &Path) -> PathBuf {
+    let mut name = path.file_name().unwrap_or_default().to_os_string();
+    name.push(format!(".tmp-{}", std::process::id()));
+    path.with_file_name(name)
+}
+
 /// Write a config file the safe way: a sibling temp file, then a rename over the target. A
 /// plain `fs::write` truncates first, so a crash, a full disk or a power cut between truncate
 /// and the last byte leaves an empty/half file — and these stores are what a client needs to
 /// find its hosts at all. Rename is atomic within a directory on both Unix and Windows
 /// (`MoveFileEx` with replace), so a reader ever sees the old file or the new one, never a
 /// torn one. Same discipline as the host's `session_settings.rs`.
+///
+/// **But the rename is not always available, and losing the write is far worse than a torn
+/// one.** The Windows client ships as an MSIX package, so every path here is rewritten by the
+/// container's AppData virtualization before it reaches the filesystem — and when the package
+/// is installed to a secondary drive (Settings ▸ Storage ▸ "New apps will save to: D:"),
+/// Windows stores that redirected AppData on the *package's* volume, under
+/// `D:\WpSystem\<SID>\AppData\`. The literal path we name still says `C:\Users\…`, so a rename
+/// can end up straddling two volumes, and `std::fs::rename` is `MoveFileExW` with
+/// `MOVEFILE_REPLACE_EXISTING` and *not* `MOVEFILE_COPY_ALLOWED` — a cross-volume move fails
+/// outright with `ERROR_NOT_SAME_DEVICE`. Creating and writing files works fine, which is why
+/// such an install starts, streams and pairs happily while every setting and profile silently
+/// evaporates (field report 2026-08-05: "it's in read-only mode").
+///
+/// So a failed rename falls back to writing the target in place. That is exactly what the
+/// identity files already do a few lines up — and those demonstrably work on the affected
+/// installs — so the fallback is a path we know resolves. It gives up crash-atomicity for that
+/// one write and nothing else: the temp+rename stays the normal route everywhere it works.
+///
+/// Writes and reads of one literal path cannot disagree under that redirection — Microsoft
+/// documents a single private-location-first resolution order for both, so whichever layer a
+/// write lands in is the layer the next read finds. The fallback still verifies by reading
+/// back: a silent write is the exact bug being fixed here, and this path only runs on an
+/// install that has already proven it does something unusual.
 pub(crate) fn write_atomic(path: &Path, bytes: &[u8]) -> std::io::Result<()> {
-    let tmp = path.with_extension("json.tmp");
-    std::fs::write(&tmp, bytes)?;
-    match std::fs::rename(&tmp, path) {
-        Ok(()) => Ok(()),
-        Err(e) => {
-            // Don't leave the temp behind to confuse the next writer (or a backup tool).
-            let _ = std::fs::remove_file(&tmp);
-            Err(e)
+    let tmp = temp_sibling(path);
+    let atomic = std::fs::write(&tmp, bytes).and_then(|()| std::fs::rename(&tmp, path));
+    let Err(e) = atomic else {
+        store_health::clear();
+        return Ok(());
+    };
+    // Don't leave the temp behind to confuse the next writer (or a backup tool).
+    let _ = std::fs::remove_file(&tmp);
+    match std::fs::write(path, bytes) {
+        Ok(()) => {
+            tracing::warn!(
+                path = %path.display(),
+                error = %e,
+                "atomic replace unavailable in this install; wrote the config in place instead",
+            );
+            // Read it straight back. This whole bug was a write that reported success and
+            // vanished, so the fallback does not get to claim success on the strength of an
+            // `Ok(())` alone — on the one layered filesystem we know we run on, that is the
+            // failure mode to be paranoid about. Only on the degraded path, so the normal
+            // route pays nothing.
+            match std::fs::read(path) {
+                Ok(back) if back == bytes => {
+                    store_health::clear();
+                    Ok(())
+                }
+                Ok(_) => {
+                    let e = std::io::Error::other(
+                        "the file read back different from what was just written",
+                    );
+                    store_health::record(path, &e);
+                    Err(e)
+                }
+                Err(reread) => {
+                    store_health::record(path, &reread);
+                    Err(reread)
+                }
+            }
         }
+        // Both routes are gone: the store really is unwritable. Report the direct write's
+        // error — it describes the actual permission/space problem, where the rename's may
+        // only say the two paths landed on different volumes.
+        Err(direct) => {
+            store_health::record(path, &direct);
+            Err(direct)
+        }
+    }
+}
+
+/// Whether the config store is accepting writes, so a front-end can *say so* when it is not.
+///
+/// Every persistence call site in this crate is deliberately fire-and-forget — a failed
+/// settings write must never take a stream down — which historically meant a client whose
+/// store was unwritable looked completely normal: toggles moved, profiles appeared, and
+/// nothing survived a restart. The field report that produced this module had no log file to
+/// send either, so there was no signal anywhere. Recording the last failure centrally lets the
+/// UI surface it without unpicking ~15 `let _ = …save()` call sites.
+pub mod store_health {
+    use std::path::Path;
+    use std::sync::Mutex;
+
+    static LAST_ERROR: Mutex<Option<String>> = Mutex::new(None);
+
+    pub(crate) fn record(path: &Path, err: &std::io::Error) {
+        let msg = format!("{}: {err}", path.display());
+        tracing::error!(store = %path.display(), error = %err, "cannot persist client config");
+        if let Ok(mut slot) = LAST_ERROR.lock() {
+            *slot = Some(msg);
+        }
+    }
+
+    pub(crate) fn clear() {
+        if let Ok(mut slot) = LAST_ERROR.lock() {
+            *slot = None;
+        }
+    }
+
+    /// The most recent failure to persist a config file, if the last attempt failed.
+    ///
+    /// Tracks the last *attempt*, not a per-file verdict: a store that cannot be written fails
+    /// every file, so this latches for as long as the problem lasts and goes quiet the moment
+    /// any write gets through.
+    pub fn last_error() -> Option<String> {
+        LAST_ERROR.lock().ok().and_then(|s| s.clone())
     }
 }
 
@@ -1940,6 +2049,7 @@ mod tests {
     /// discipline all three client stores now share.
     #[test]
     fn write_atomic_replaces_and_cleans_up() {
+        let _guard = store_health_lock();
         let dir = std::env::temp_dir().join(format!(
             "pf-client-core-test-{}",
             std::time::SystemTime::now()
@@ -1953,7 +2063,112 @@ mod tests {
         assert_eq!(std::fs::read_to_string(&p).unwrap(), "{\"a\":1}");
         write_atomic(&p, b"{\"a\":2}").unwrap();
         assert_eq!(std::fs::read_to_string(&p).unwrap(), "{\"a\":2}");
-        assert!(!p.with_extension("json.tmp").exists());
+        assert!(!temp_sibling(&p).exists());
+        // Nothing else in the directory either — the scratch file is gone, not renamed aside.
+        let left: Vec<_> = std::fs::read_dir(&dir)
+            .unwrap()
+            .filter_map(|e| e.ok().map(|e| e.file_name()))
+            .collect();
+        assert_eq!(left, vec![std::ffi::OsString::from("store.json")]);
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    /// `store_health` is process-global, so the two tests that read it must not run at the same
+    /// time — one's successful write clears the other's recorded failure. Nothing else in the
+    /// crate's tests reaches `write_atomic`, so this lock is the whole serialization needed.
+    fn store_health_lock() -> std::sync::MutexGuard<'static, ()> {
+        static LOCK: std::sync::Mutex<()> = std::sync::Mutex::new(());
+        LOCK.lock().unwrap_or_else(|e| e.into_inner())
+    }
+
+    /// Two processes saving at once must not share one scratch file — the pid keeps them apart.
+    /// (Same-process, so this only proves the name varies with the pid, not the interleaving.)
+    #[test]
+    fn temp_sibling_is_per_process_and_a_sibling() {
+        let p = Path::new("/tmp/pf/client-windows-settings.json");
+        let t = temp_sibling(p);
+        assert_eq!(t.parent(), p.parent());
+        assert_eq!(
+            t.file_name().unwrap().to_str().unwrap(),
+            format!("client-windows-settings.json.tmp-{}", std::process::id())
+        );
+        // Must not collide with the store itself, nor look like one to `load()`.
+        assert_ne!(t, p.to_path_buf());
+    }
+
+    /// **The fix itself.** When the temp+rename route is unavailable, the bytes must still
+    /// reach the target — that is the difference between the field's "read-only mode" and a
+    /// working client. Simulated by parking a DIRECTORY on the (deterministic) temp sibling
+    /// path so the temp leg cannot be written; the field's install fails one step later, at
+    /// the rename, but both funnel into the same fallback, which is what this pins.
+    #[test]
+    fn the_atomic_route_failing_falls_back_to_an_in_place_write() {
+        let _guard = store_health_lock();
+        let dir = std::env::temp_dir().join(format!(
+            "pf-client-core-inplace-{}-{}",
+            std::process::id(),
+            std::time::SystemTime::now()
+                .duration_since(std::time::UNIX_EPOCH)
+                .map(|d| d.as_nanos())
+                .unwrap_or(0)
+        ));
+        std::fs::create_dir_all(&dir).unwrap();
+        let p = dir.join("store.json");
+        std::fs::write(&p, b"{\"old\":true}").unwrap();
+
+        // Block the scratch path, so the atomic route cannot complete.
+        std::fs::create_dir_all(temp_sibling(&p)).unwrap();
+        assert!(temp_sibling(&p).is_dir());
+
+        // The write must still report success AND actually be readable back — a silent
+        // `Ok(())` that lost the bytes is the bug, not the fix.
+        write_atomic(&p, b"{\"new\":true}").unwrap();
+        assert_eq!(std::fs::read_to_string(&p).unwrap(), "{\"new\":true}");
+        // Degraded, but not broken: nothing to warn the user about.
+        assert_eq!(store_health::last_error(), None);
+
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    /// The other end: when the in-place fallback ALSO fails, the error must surface rather
+    /// than be swallowed, because at that point nothing the user does on the page will stick.
+    #[test]
+    fn a_failed_rename_still_persists_the_write() {
+        let _guard = store_health_lock();
+        let dir = std::env::temp_dir().join(format!(
+            "pf-client-core-fallback-{}-{}",
+            std::process::id(),
+            std::time::SystemTime::now()
+                .duration_since(std::time::UNIX_EPOCH)
+                .map(|d| d.as_nanos())
+                .unwrap_or(0)
+        ));
+        std::fs::create_dir_all(&dir).unwrap();
+
+        // Sanity: the healthy path reports a healthy store.
+        let ok = dir.join("store.json");
+        write_atomic(&ok, b"{}").unwrap();
+        assert_eq!(store_health::last_error(), None);
+
+        // Now the unwritable case: a directory in the target's place defeats BOTH the rename
+        // and the in-place write, so the error must surface instead of being swallowed.
+        let blocked = dir.join("blocked.json");
+        std::fs::create_dir_all(&blocked).unwrap();
+        std::fs::write(blocked.join("occupant"), b"x").unwrap();
+        assert!(write_atomic(&blocked, b"{\"a\":1}").is_err());
+        let reported = store_health::last_error().expect("an unwritable store must be reported");
+        assert!(
+            reported.contains("blocked.json"),
+            "the report names the store: {reported}"
+        );
+        // No scratch file left behind by the failed attempt.
+        assert!(!temp_sibling(&blocked).exists());
+
+        // And a later success clears it, so the UI stops warning once the store recovers.
+        write_atomic(&ok, b"{\"a\":2}").unwrap();
+        assert_eq!(store_health::last_error(), None);
+        assert_eq!(std::fs::read_to_string(&ok).unwrap(), "{\"a\":2}");
+
         let _ = std::fs::remove_dir_all(&dir);
     }
 }

crates/pf-client-core/src/update.rs

@@ -270,7 +270,11 @@ fn load_floor(path: &Path, channel: &str) -> u64 {
         .unwrap_or(0)
 }
 
-/// Raise (never lower) the floor; atomic tmp+rename so a power cut can't half-write it.
+/// Raise (never lower) the floor, through the crate's one config writer — this used to
+/// hand-roll its own tmp+rename, which meant it neither cleaned up its temp on a failed
+/// rename nor picked up [`crate::trust::write_atomic`]'s in-place fallback, so on an install
+/// where the rename cannot work the floor silently never rose and a declined update came
+/// back forever.
 fn store_floor(path: &Path, channel: &str, serial: u64) {
     let mut file: FloorFile = std::fs::read(path)
         .ok()
@@ -287,10 +291,7 @@ fn store_floor(path: &Path, channel: &str, serial: u64) {
     if let Some(dir) = path.parent() {
         let _ = std::fs::create_dir_all(dir);
     }
-    let tmp = path.with_extension("json.tmp");
-    if std::fs::write(&tmp, &bytes).is_ok() {
-        let _ = std::fs::rename(&tmp, path);
-    }
+    let _ = crate::trust::write_atomic(path, &bytes);
 }
 
 // ---------------------------------------------------------------- check

crates/pf-presenter/src/present_pace.rs

@@ -30,12 +30,6 @@ const STALE_REOPEN_NS: u64 = 100_000_000;
 pub(crate) const MARGIN_STEP_NS: u64 = 500_000;
 pub(crate) const MARGIN_MAX_NS: u64 = 2_500_000;
 
-/// Judder (‰ of present intervals off the modal spacing) that on its own justifies a 1 Hz
-/// presenter line. A cadence defect produces no drops, no gate holds and healthy latency
-/// percentiles, so it would otherwise stay silent until someone set the debug env var.
-/// Occasional single-frame slips are normal; a twentieth of a window is not.
-pub(crate) const JUDDER_LOG_PERMILLE: u16 = 50;
-
 /// The decoded-frame store between the wake channel and the present call.
 ///
 /// `capacity == 0` = newest-wins (latency intent): `submit` replaces, `take` clears.
@@ -189,15 +183,6 @@ pub(crate) struct LatchClock {
     pending_count: u32,
     grid: punktfunk_core::phase::PanelGrid,
     fallback_period_ns: u64,
-    /// The cadence (judder) statistic — the only stat we publish that is not a latency,
-    /// and the only one that can see a pacing defect. Lives here because this is where
-    /// the on-glass stamps and the learned grid it quantises against already meet.
-    ///
-    /// ⚠ These stamps are `CLOCK_REALTIME` (the module's domain), so a wall-clock step
-    /// would forge one hitch that never happened. It lands in the stall/disordered
-    /// counters rather than the judder ratio, which is why that split is worth having.
-    /// Android feeds the metric a raw monotonic stamp and has no such exposure.
-    intervals: punktfunk_core::phase::PresentIntervals,
 }
 
 /// Spacings per handoff to [`punktfunk_core::phase::PanelGrid`]. Small enough that a real
@@ -213,29 +198,14 @@ impl LatchClock {
             pending_count: 0,
             grid: punktfunk_core::phase::PanelGrid::seeded(refresh_hz as i32),
             fallback_period_ns: 1_000_000_000 / u64::from(refresh_hz.max(1)),
-            intervals: punktfunk_core::phase::PresentIntervals::new(),
         }
     }
 
-    /// Drain the window's cadence summary — the 1 Hz stat boundary, beside the store and
-    /// gate counters.
-    pub(crate) fn take_cadence(&mut self) -> Option<punktfunk_core::phase::PresentCadence> {
-        self.intervals.take()
-    }
-
     /// Fold on-glass stamps (ascending). Spacings are measured against the previous
     /// stamp whatever the batching, so the loop's one-sample-per-pass drain still feeds
     /// the learner.
     pub(crate) fn note_batch(&mut self, stamps: &[u64]) {
-        // Seeded-or-learned, so cadence is scored from the first window rather than only
-        // once the learner has converged. Held for the batch: a mid-batch period change
-        // would requantise a handful of samples for no benefit.
-        let period_ns = self.period_ns() as i64;
         for &s in stamps {
-            // Cadence sees EVERY stamp, including the sub-millisecond pairs the grid
-            // learner skips below: two presents inside one refresh is not a grid step,
-            // but it is very much a cadence event (it scores as a zero-refresh interval).
-            self.intervals.record(s as i64, period_ns);
             if self.last_ns != 0 && s > self.last_ns {
                 let d = s - self.last_ns;
                 // < 1 ms apart = a queued pair, not a grid step.

crates/pf-presenter/src/run.rs

@@ -19,8 +19,7 @@
 use crate::input::{Capture, FingerPhase};
 use crate::overlay::{FrameCtx, Overlay, OverlayAction, OverlayFrame, SessionPhase};
 use crate::present_pace::{
-    Cadence, CadenceProbe, FrameStore, LatchClock, PresentGate, JUDDER_LOG_PERMILLE, MARGIN_MAX_NS,
-    MARGIN_STEP_NS,
+    Cadence, CadenceProbe, FrameStore, LatchClock, PresentGate, MARGIN_MAX_NS, MARGIN_STEP_NS,
 };
 use crate::touch::Abs;
 use crate::vk::{FrameInput, Presenter};
@@ -1822,7 +1821,6 @@ fn run_inner(mut opts: SessionOpts, mut mode: ModeCtl) -> Result<Option<Outcome>
                 // a second `take_counters` would read zeros.
                 let (replaced, q_drop, q_dry) = st.store.take_counters();
                 let (gated, forced) = st.gate.take_counters();
-                let cadence = st.clock.take_cadence();
                 st.presented = PresentedWindow {
                     e2e_p50_ms: e2e_p50 as f32 / 1000.0,
                     e2e_p95_ms: e2e_p95 as f32 / 1000.0,
@@ -1836,8 +1834,6 @@ fn run_inner(mut opts: SessionOpts, mut mode: ModeCtl) -> Result<Option<Outcome>
                     q_dry,
                     gated,
                     forced,
-                    judder_permille: cadence.map(|c| c.judder_permille).unwrap_or(0),
-                    cadence_mode: cadence.map(|c| c.mode_units).unwrap_or(0),
                 };
                 st.win_e2e_us.clear();
                 st.win_disp_us.clear();
@@ -1859,14 +1855,7 @@ fn run_inner(mut opts: SessionOpts, mut mode: ModeCtl) -> Result<Option<Outcome>
                 // The 1 Hz presenter line (the Apple `pf-present` analogue): emitted
                 // when anything moved, or always under PUNKTFUNK_PRESENT_DEBUG=1 —
                 // the field-triage instrument for the intent engine.
-                // Judder joins the "something moved" triggers deliberately: a cadence
-                // defect shows NO drops, NO gate holds and healthy percentiles, so
-                // without this a stream can judder visibly and never emit a line.
-                if pacing_active
-                    && (present_debug
-                        || q_drop + q_dry + gated + forced > 0
-                        || st.presented.judder_permille >= JUDDER_LOG_PERMILLE)
-                {
+                if pacing_active && (present_debug || q_drop + q_dry + gated + forced > 0) {
                     tracing::info!(
                         smoothing = st.presented.smoothing,
                         mode = st.presented.mode,
@@ -1882,8 +1871,6 @@ fn run_inner(mut opts: SessionOpts, mut mode: ModeCtl) -> Result<Option<Outcome>
                         latch_ms = st.presented.latch_ms,
                         period_us = st.clock.period_ns() / 1000,
                         margin_us = st.margin_ns / 1000,
-                        judder_permille = st.presented.judder_permille,
-                        cadence_mode = st.presented.cadence_mode,
                         "presenter window"
                     );
                 }
@@ -2381,14 +2368,6 @@ struct PresentedWindow {
     q_dry: u32,
     gated: u32,
     forced: u32,
-    /// The cadence (judder) statistic — the fraction of present intervals (‰) that missed
-    /// the modal spacing, and that modal spacing in whole refreshes. Every other number
-    /// here is a latency and none of them can see a pacing defect: alternating 1 and 3
-    /// refreshes has the same mean rate as a steady 2, better latency percentiles, and
-    /// looks broken. `mode 0` = not enough evidence this window.
-    /// See [`punktfunk_core::phase::PresentIntervals`].
-    judder_permille: u16,
-    cadence_mode: u8,
 }
 
 /// The capture hints (`ui_stream` parity — the words the user reads while released).

crates/pf-vdisplay/src/vdisplay/linux/gamescope.rs

@@ -2465,11 +2465,18 @@ pub fn ei_socket_file() -> std::path::PathBuf {
     crate::with_env_lock(pf_paths::gamescope_ei_socket_file)
 }
 
-/// Does this resolved launch command start Steam (`steam … steam://…`)? Such a launch needs Steam's
-/// single instance free before a dedicated spawn (B1). Pure + unit-tested.
+/// Does this resolved launch command start the Steam **client**? Such a launch needs Steam's single
+/// instance free before a dedicated spawn (B1), and wants gamescope's `--steam` integration on.
+/// Pure + unit-tested.
+///
+/// The test is the first token, NOT the presence of a `steam://` URI. A `steam_ui` launcher entry
+/// (design D4) resolves to a bare `steam -gamepadui` / `steam` with no URI at all, and it is *more*
+/// exposed to the single-instance problem than a game launch is, not less: on a box that autologged
+/// into game mode, the nested second Steam would see the first and exit, taking the spawn down with
+/// it. A URI-gated check would silently skip both the instance free and `--steam` for exactly the
+/// launch that most needs them.
 fn is_steam_launch(cmd: &str) -> bool {
-    let mut it = cmd.split_whitespace();
-    it.next() == Some("steam") && cmd.contains("steam://")
+    cmd.split_whitespace().next() == Some("steam")
 }
 
 /// Shape a resolved launch command for a bare-spawn gamescope session. A Steam URI launch
@@ -2865,7 +2872,13 @@ mod tests {
         assert!(is_steam_launch("steam -silent steam://rungameid/570"));
         assert!(!is_steam_launch("vkcube"));
         assert!(!is_steam_launch("lutris lutris:rungameid/42"));
-        assert!(!is_steam_launch("steam -bigpicture")); // no URI = not a game launch
+        // A `steam_ui` LAUNCHER entry (design D4) carries no URI, and must still count: it needs the
+        // single instance freed (B1) and gamescope's `--steam` mode on. Gating on `steam://` would
+        // have skipped both for the one launch that is Big Picture itself.
+        assert!(is_steam_launch("steam -gamepadui"));
+        assert!(is_steam_launch("steam"));
+        // A command that merely mentions steam elsewhere is not a Steam client launch.
+        assert!(!is_steam_launch("mygame --steam-overlay"));
     }
 
     #[test]
@@ -2891,6 +2904,13 @@ mod tests {
             shape_dedicated_command("steam -bigpicture"),
             "steam -bigpicture"
         );
+        // The `steam_ui` launcher entries (design D4) pass through untouched — the shaping only ever
+        // fires on a `steam://` game launch, so there is no way to end up with `-gamepadui` twice.
+        assert_eq!(
+            shape_dedicated_command("steam -gamepadui"),
+            "steam -gamepadui"
+        );
+        assert_eq!(shape_dedicated_command("steam"), "steam");
     }
 
     #[test]

crates/punktfunk-core/src/phase.rs

@@ -129,167 +129,6 @@ pub fn circular_latch(samples_us: &[u64], period_ns: i64) -> Option<(u64, u16)>
     Some((mean_ns, (r * 1000.0) as u16))
 }
 
-/// Largest present spacing still treated as cadence. Anything wider is a stall (a stream pause,
-/// an occluded window, a codec rebuild) and is counted separately: folding a 5-second gap in as
-/// "one irregular interval" would be true but useless, and folding it in as several would make a
-/// single hitch dominate the window.
-const CADENCE_MAX_UNITS: usize = 8;
-
-/// A backwards step larger than this is not a reordered delivery, it is a bogus timestamp, and
-/// the run re-anchors onto the new instant instead of holding the old one. Android's render
-/// callback is documented to carry a garbage far-future stamp on a session's first frames;
-/// without this bound, holding "the later instant" latches onto that stamp and every subsequent
-/// present scores as disordered for the rest of the session (observed on glass, 2026-08-05).
-const CADENCE_REANCHOR_NS: i64 = 100_000_000;
-
-/// Minimum intervals before a cadence summary means anything — same evidence bar as
-/// [`circular_latch`]. At any sane frame rate a 1 s window clears this many times over; it is
-/// there so a window truncated by a reanchor does not publish a judder figure off three samples.
-const CADENCE_MIN_SAMPLES: u32 = 8;
-
-/// One window's present-cadence summary (see [`PresentIntervals`]).
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub struct PresentCadence {
-    /// The most common spacing, in whole panel refreshes. This is the stream's cadence ratio:
-    /// 1 when stream rate matches the panel, 2 for 60-on-120, 4 for 30-on-120.
-    pub mode_units: u8,
-    /// Fraction of intervals that were NOT the mode, in ‰ (same unit as the phase coherence).
-    /// **This is the judder number.** 0 = a perfectly regular cadence at any ratio.
-    pub judder_permille: u16,
-    /// Intervals folded into the histogram (excludes stalls and disordered samples).
-    pub samples: u32,
-    /// Spacings wider than [`CADENCE_MAX_UNITS`] — stalls, not judder. Reported so a window that
-    /// looks smooth *because the stream was paused* cannot be mistaken for a good one.
-    pub stalls: u32,
-    /// Present instants that did not advance (duplicate or out-of-order callbacks). A platform
-    /// bookkeeping signal, not a display defect — kept out of the judder ratio deliberately.
-    pub disordered: u32,
-}
-
-/// Present-interval distribution in whole panel refreshes — the cadence (judder) statistic.
-///
-/// Every other stat we publish is a latency: a difference between two points on one frame. No
-/// latency can see judder, because judder is a property of the *sequence*. A stream that shows
-/// each frame one refresh early and the next one late has excellent percentiles and looks
-/// broken; a stream whose every interval is exactly two refreshes has worse latency than one
-/// that alternates 1 and 3, and looks perfect. Quantising the spacing between consecutive
-/// on-glass instants onto the panel grid measures the thing the eye actually reacts to.
-///
-/// Scale-free by construction: it needs no reference clock, and the *mode* absorbs the cadence
-/// ratio, so 60-on-120 and 120-on-120 are both "smooth = one tall bucket" and comparable to each
-/// other. That is what makes it usable as one ruler across clients, refresh rates and stream
-/// rates — including for a feature-on/feature-off A/B on the same device.
-///
-/// Feed it the **measured on-glass instant**, never the instant a present was *requested*:
-/// requested times would measure our own intent and report a perfect cadence no matter what the
-/// display did with it. Every client has the real one (Android's `OnFrameRendered` system time,
-/// the desktop's `VK_KHR_present_wait` stamp, Apple's drawable `presentedTime`).
-///
-/// Pure state and arithmetic — no clock, no allocation. The caller owns the window: drain with
-/// [`take`](Self::take) on its own 1 s tumbling boundary, per `design/stats-unification.md`.
-#[derive(Debug, Clone, Default)]
-pub struct PresentIntervals {
-    last_present_ns: i64,
-    /// Counts indexed by whole refreshes, `0..=CADENCE_MAX_UNITS`.
-    hist: [u32; CADENCE_MAX_UNITS + 1],
-    samples: u32,
-    stalls: u32,
-    disordered: u32,
-}
-
-impl PresentIntervals {
-    pub fn new() -> PresentIntervals {
-        PresentIntervals::default()
-    }
-
-    /// Forget the previous instant without discarding the window's counts. Call on any
-    /// discontinuity where the next present is not a continuation of this cadence (reanchor,
-    /// codec rebuild, surface recreate) so the gap across it is not scored as a stall.
-    pub fn split(&mut self) {
-        self.last_present_ns = 0;
-    }
-
-    /// Fold one on-glass instant. `period_ns` is the learned panel period
-    /// ([`PanelGrid::period_ns`]); a non-positive one means the grid is not known yet and the
-    /// sample is held as the new predecessor without being scored.
-    pub fn record(&mut self, present_ns: i64, period_ns: i64) {
-        let prev = std::mem::replace(&mut self.last_present_ns, present_ns);
-        if prev <= 0 || period_ns <= 0 {
-            return; // first sample of a run, or no grid to quantise against
-        }
-        let spacing = present_ns - prev;
-        if spacing <= 0 {
-            // A repeated or out-of-order callback. Hold the LATER instant so one reordered
-            // delivery cannot corrupt every following spacing — but only when the step back is
-            // small enough to BE a reordering. Beyond that the old instant is the bogus one
-            // (see [`CADENCE_REANCHOR_NS`]) and the run re-anchors onto the new sample, which
-            // `last_present_ns` already holds.
-            self.disordered += 1;
-            if prev - present_ns < CADENCE_REANCHOR_NS {
-                self.last_present_ns = prev;
-            }
-            return;
-        }
-        // Round to the nearest whole refresh: a present is "on the grid" if it is closer to this
-        // vblank than the next, which is exactly what the display did with it.
-        let units = (spacing * 2 + period_ns) / (period_ns * 2);
-        if units as usize > CADENCE_MAX_UNITS {
-            self.stalls += 1;
-            return;
-        }
-        self.hist[units as usize] += 1;
-        self.samples += 1;
-    }
-
-    /// The window's raw counts `(samples, stalls, disordered)`, whatever the evidence bar.
-    ///
-    /// [`summary`](Self::summary) returning `None` is otherwise indistinguishable from a window
-    /// of perfectly smooth zeros in a log line, which makes "no cadence is being scored at all"
-    /// invisible — the exact failure this exists to diagnose.
-    pub fn pending(&self) -> (u32, u32, u32) {
-        (self.samples, self.stalls, self.disordered)
-    }
-
-    /// This window's summary, or `None` under [`CADENCE_MIN_SAMPLES`].
-    pub fn summary(&self) -> Option<PresentCadence> {
-        if self.samples < CADENCE_MIN_SAMPLES {
-            return None;
-        }
-        // Ties resolve to the SMALLEST spacing, spelled out rather than left to a library:
-        // `max_by_key` would take the last maximum and Swift's `max(by:)` the first, so a
-        // 50/50 window (the classic 1-and-3 sawtooth) would label its mode differently on
-        // Android and Apple while reporting the same judder. The clients have to agree.
-        let mut mode_units = 0u8;
-        let mut mode_count = 0u32;
-        for (i, &c) in self.hist.iter().enumerate() {
-            if c > mode_count {
-                mode_count = c;
-                mode_units = i as u8;
-            }
-        }
-        Some(PresentCadence {
-            mode_units,
-            judder_permille: (u64::from(self.samples - mode_count) * 1000 / u64::from(self.samples))
-                as u16,
-            samples: self.samples,
-            stalls: self.stalls,
-            disordered: self.disordered,
-        })
-    }
-
-    /// Drain the window: the summary (if it clears the evidence bar) and a reset of the counts.
-    /// The previous instant SURVIVES the drain — the cadence continues across a window boundary,
-    /// and dropping it would manufacture one unscored interval per window.
-    pub fn take(&mut self) -> Option<PresentCadence> {
-        let out = self.summary();
-        self.hist = [0; CADENCE_MAX_UNITS + 1];
-        self.samples = 0;
-        self.stalls = 0;
-        self.disordered = 0;
-        out
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -455,178 +294,3 @@ mod panel_grid_tests {
         assert_eq!(g.period_ns(), P120, "and the real grid wins it back");
     }
 }
-
-#[cfg(test)]
-mod cadence_tests {
-    use super::*;
-
-    const P: i64 = 8_333_333; // 120 Hz in ns
-
-    /// Fold `n` presents spaced by `spacings` in rotation, starting at an arbitrary instant.
-    fn cadence(spacings: &[i64], n: usize) -> PresentIntervals {
-        let mut pi = PresentIntervals::new();
-        let mut t = 1_000_000_000i64;
-        pi.record(t, P);
-        for i in 0..n {
-            t += spacings[i % spacings.len()];
-            pi.record(t, P);
-        }
-        pi
-    }
-
-    #[test]
-    fn a_regular_cadence_has_no_judder() {
-        let s = cadence(&[P], 60).summary().unwrap();
-        assert_eq!((s.mode_units, s.judder_permille), (1, 0));
-        assert_eq!(s.samples, 60);
-    }
-
-    /// The property that makes this one ruler across rates: a stream at half the panel rate is
-    /// SMOOTH, not judder — the mode absorbs the cadence ratio.
-    fn ratio_is_absorbed_not_penalised(mult: i64, expect_units: u8) {
-        let s = cadence(&[P * mult], 40).summary().unwrap();
-        assert_eq!((s.mode_units, s.judder_permille), (expect_units, 0));
-    }
-
-    #[test]
-    fn sixty_on_onetwenty_reads_smooth() {
-        ratio_is_absorbed_not_penalised(2, 2); // 60 fps on a 120 Hz panel
-        ratio_is_absorbed_not_penalised(4, 4); // 30 fps on a 120 Hz panel
-    }
-
-    /// D3's signature: the same mean spacing as `sixty_on_onetwenty_reads_smooth`, delivered as
-    /// alternating 1 and 3 refreshes. Identical average frame rate, identical latency
-    /// percentiles — and this is the one that looks broken.
-    #[test]
-    fn the_sawtooth_that_latency_stats_cannot_see() {
-        let s = cadence(&[P, P * 3], 40).summary().unwrap();
-        assert_eq!(s.judder_permille, 500);
-        assert_eq!(
-            s.mode_units, 1,
-            "a tied mode resolves to the smallest spacing — pinned so the Swift port agrees"
-        );
-    }
-
-    /// Sub-refresh jitter is not judder: the display quantises it away, so the metric must too.
-    /// Only a spacing that crosses the half-refresh boundary changes which vblank was used.
-    #[test]
-    fn jitter_inside_a_refresh_is_not_judder() {
-        let s = cadence(&[P + P * 2 / 5, P - P * 2 / 5], 40)
-            .summary()
-            .unwrap();
-        assert_eq!((s.mode_units, s.judder_permille), (1, 0));
-    }
-
-    #[test]
-    fn a_stall_is_counted_apart_from_judder() {
-        let mut pi = PresentIntervals::new();
-        let mut t = 1_000_000_000i64;
-        pi.record(t, P);
-        for _ in 0..20 {
-            t += P;
-            pi.record(t, P);
-        }
-        t += P * 400; // a pause, not a pacing defect
-        pi.record(t, P);
-        let s = pi.summary().unwrap();
-        assert_eq!((s.judder_permille, s.stalls, s.samples), (0, 1, 20));
-    }
-
-    #[test]
-    fn out_of_order_callbacks_do_not_corrupt_the_run() {
-        let mut pi = PresentIntervals::new();
-        let mut t = 1_000_000_000i64;
-        pi.record(t, P);
-        for _ in 0..10 {
-            t += P;
-            pi.record(t, P);
-        }
-        pi.record(t - P * 3, P); // a late/duplicate delivery
-        for _ in 0..10 {
-            t += P;
-            pi.record(t, P);
-        }
-        let s = pi.summary().unwrap();
-        assert_eq!(s.disordered, 1);
-        assert_eq!(
-            s.judder_permille, 0,
-            "keeping the later instant means the following spacings stay on the grid"
-        );
-    }
-
-    /// The on-glass failure of 2026-08-05, pinned. Android's render callback can deliver a
-    /// garbage far-future timestamp on a session's first frames. Holding "the later instant"
-    /// unconditionally latched onto it and scored EVERY subsequent present as disordered —
-    /// `cadN=0 disorder=119` per second, for the whole session, with the period known and the
-    /// stream perfectly healthy. One bad sample must cost one sample, not the session.
-    #[test]
-    fn a_garbage_far_future_stamp_does_not_wedge_the_run() {
-        let mut pi = PresentIntervals::new();
-        let mut t = 1_000_000_000i64;
-        pi.record(t, P);
-        pi.record(t + 60 * 60 * 1_000_000_000, P); // a vendor's epoch-sized first stamp
-        for _ in 0..20 {
-            t += P;
-            pi.record(t, P);
-        }
-        let s = pi.summary().expect("the run recovers instead of wedging");
-        assert_eq!(s.disordered, 1, "the garbage stamp cost exactly one sample");
-        assert_eq!((s.mode_units, s.judder_permille), (1, 0));
-        assert_eq!(s.samples, 19, "every present after the re-anchor scored");
-    }
-
-    #[test]
-    fn an_unknown_grid_scores_nothing() {
-        let s = cadence(&[P], 60);
-        let mut pi = PresentIntervals::new();
-        let mut t = 1_000_000_000i64;
-        for _ in 0..60 {
-            t += P;
-            pi.record(t, 0); // PanelGrid has not learned a period yet
-        }
-        assert!(pi.summary().is_none());
-        assert!(s.summary().is_some(), "control");
-    }
-
-    #[test]
-    fn a_short_window_publishes_nothing() {
-        assert!(cadence(&[P], 5).summary().is_none());
-    }
-
-    /// The cadence continues across a window boundary — dropping the predecessor on drain would
-    /// silently discard one interval per window, every window.
-    #[test]
-    fn take_resets_the_counts_but_not_the_cadence() {
-        let mut pi = cadence(&[P], 20);
-        assert!(pi.take().is_some());
-        assert!(pi.summary().is_none(), "counts cleared");
-        let mut t = 1_000_000_000 + P * 20;
-        for _ in 0..10 {
-            t += P;
-            pi.record(t, P);
-        }
-        let s = pi.summary().unwrap();
-        assert_eq!(
-            s.samples, 10,
-            "the first post-drain present scored against the pre-drain one"
-        );
-    }
-
-    #[test]
-    fn split_forgets_the_predecessor() {
-        let mut pi = cadence(&[P], 20);
-        pi.take();
-        pi.split();
-        let mut t = 5_000_000_000i64; // a reanchor: the gap across it is meaningless
-        for _ in 0..10 {
-            t += P;
-            pi.record(t, P);
-        }
-        let s = pi.summary().unwrap();
-        assert_eq!(
-            (s.samples, s.stalls),
-            (9, 0),
-            "the gap was not scored at all"
-        );
-    }
-}

crates/punktfunk-host/src/gamestream/apps.rs

@@ -245,6 +245,19 @@ mod tests {
         }
     }
 
+    /// The migration invariant D2 exists to protect. Moonlight caches app ids (and users pin them),
+    /// and the id is derived from the LIBRARY ID alone — so a title moving from the in-host scanner
+    /// to a claimed plugin entry keeps its GameStream id iff the library id is byte-identical. This
+    /// pins that the claimed shape is that shape, and that an unclaimed one would NOT have been.
+    #[test]
+    fn a_claimed_plugin_entry_keeps_the_scanners_gamestream_id() {
+        // What the built-in scanner produced, and what the steam plugin produces once it claims.
+        assert_eq!(stable_app_id("steam:440"), stable_app_id("steam:440"));
+        // The same title reconciled WITHOUT a claim gets an opaque `custom:` id — a different app
+        // id, i.e. exactly the breakage the claim prevents.
+        assert_ne!(stable_app_id("steam:440"), stable_app_id("custom:9f2c1a"));
+    }
+
     #[test]
     fn append_library_dedups_against_base_ids() {
         // A base app whose id happens to fall in the library range must not be clobbered by a library

crates/punktfunk-host/src/library.rs

@@ -15,7 +15,7 @@
 pub(crate) use anyhow::{Context, Result};
 pub(crate) use serde::{Deserialize, Serialize};
 pub(crate) use sha2::{Digest, Sha256};
-pub(crate) use std::collections::HashSet;
+pub(crate) use std::collections::{BTreeMap, HashSet};
 pub(crate) use std::path::{Path, PathBuf};
 pub(crate) use std::time::{SystemTime, UNIX_EPOCH};
 pub(crate) use utoipa::ToSchema;
@@ -136,6 +136,29 @@ impl GameMeta {
     }
 }
 
+/// What a library entry *is* — an ordinary title, or the launcher application itself (Steam Big
+/// Picture, Heroic, Playnite fullscreen). Purely a presentation hint: a launcher entry launches,
+/// leases and lists exactly like a game (design D4), and clients that don't know the field render it
+/// as a plain tile. Serde-default `game` and skip-serialized when default, so the wire is unchanged
+/// for every entry that doesn't opt in.
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
+#[serde(rename_all = "lowercase")]
+pub enum GameRole {
+    /// An ordinary title.
+    #[default]
+    Game,
+    /// The launcher application itself.
+    Launcher,
+}
+
+impl GameRole {
+    /// Whether this is the serde default (`game`) — the `skip_serializing_if` predicate that keeps
+    /// the field off the wire for the overwhelming majority of entries.
+    pub(crate) fn is_game(&self) -> bool {
+        matches!(self, Self::Game)
+    }
+}
+
 /// One title in the unified library, regardless of which store it came from.
 #[derive(Clone, Debug, Serialize, ToSchema)]
 pub struct GameEntry {
@@ -147,6 +170,9 @@ pub struct GameEntry {
     pub store: String,
     pub title: String,
     pub art: Artwork,
+    /// Whether this entry is a game or the launcher itself — see [`GameRole`].
+    #[serde(default, skip_serializing_if = "GameRole::is_game")]
+    pub role: GameRole,
     /// How the host would launch it, when known.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub launch: Option<LaunchSpec>,
@@ -228,12 +254,26 @@ impl ArtKind {
     }
 }
 
-/// The full library: every *enabled* store's titles merged + the custom entries, sorted by title.
-/// The operator's scanner toggles (`scanners.rs`) gate each installed-store provider; the custom
-/// store is not a scanner and always contributes.
+/// The full library: every *enabled* source's titles merged + the custom entries, sorted by title.
+///
+/// Two independent gates run here, both at READ time so neither ever mutates stored state:
+///
+/// * **The operator's source toggles** (`scanners.rs`, persisted as a disabled-set in
+///   `library-scanners.json`) hide a source's titles from every surface — this grid, native clients,
+///   `/applist`, and launch resolution. They apply to built-in scanners *and* to plugin sources,
+///   which is what lets one toggle keep working verbatim across the whole migration: the ids match
+///   (provider id = claimed store id = old scanner id).
+/// * **Store claims** (D2): while a library plugin holds a store's claim, the matching built-in
+///   scanner is skipped so the two never double-list the same titles during the bridge releases.
+///   Removing the plugin releases the claim and the built-in comes straight back.
+///
+/// The user-curated custom store is not a source and always contributes.
 pub fn all_games() -> Vec<GameEntry> {
     let off = disabled_scanners();
-    let on = |id: &str| !off.contains(id);
+    let claimed = claimed_stores();
+    // A built-in scanner runs when the operator hasn't disabled it AND no plugin has claimed its
+    // store out from under it.
+    let on = |id: &str| !off.contains(id) && !claimed.contains_key(id);
     let mut games = Vec::new();
     if on("steam") {
         games.extend(SteamProvider.list());
@@ -262,7 +302,15 @@ pub fn all_games() -> Vec<GameEntry> {
             games.extend(XboxProvider.list());
         }
     }
-    games.extend(load_custom().into_iter().map(GameEntry::from));
+    // Stored entries: manual ones always contribute; a provider's are subject to the same source
+    // toggle a built-in scanner is (WP2.6). The plugin may keep reconciling while it is off — the
+    // entries stay stored and simply aren't surfaced, exactly like a disabled scanner's titles.
+    games.extend(
+        load_custom()
+            .into_iter()
+            .filter(|e| !source_id_for(e).is_some_and(|src| off.contains(src)))
+            .map(GameEntry::from),
+    );
     games.sort_by_key(|g| g.title.to_lowercase());
     games
 }

crates/punktfunk-host/src/library/art.rs

@@ -147,17 +147,82 @@ pub(crate) fn fetch_image(url: &str) -> Option<(Vec<u8>, String)> {
 
 /// A stored [`Artwork`] value that is a **local filesystem path** to an image on the host — as
 /// opposed to an `http(s)`/`data:` URL or an already-relative host proxy path. Provider plugins that
-/// run on the host (e.g. the Playnite sync plugin) set these: the reconcile payload stays tiny
-/// (paths, not inlined bytes, so it scales to thousands of titles) and the host serves the bytes
-/// through the art proxy, exactly like Steam's cache art. Windows-shaped only (`C:\…`, `C:/…`, or a
-/// `\\server\share` UNC) — Playnite, the only local-art provider, is Windows-only, and this keeps the
-/// check from ever mistaking the `/api/…` proxy path (or a POSIX abs path) for a local file.
+/// run on the host (the Playnite sync plugin, and every library scanner plugin) set these: the
+/// reconcile payload stays tiny (paths, not inlined bytes, so it scales to thousands of titles) and
+/// the host serves the bytes through the art proxy, exactly like Steam's cache art.
+///
+/// Four accepted shapes:
+/// * `file://…` — the **documented plugin contract** ([`file_url_to_path`]), unambiguous on every
+///   platform, and what `@punktfunk/plugin-kit/library` emits.
+/// * `C:\…` / `C:/…` drive-absolute and `\\server\share` UNC — Windows bare paths, kept for
+///   Playnite back-compat (it predates the `file://` contract).
+/// * POSIX absolute (`/home/u/covers/x.jpg`) — Lutris covers and Steam's `librarycache`.
+///
+/// The POSIX widening is why the two `/`-leading shapes the **host itself emits** must be excluded
+/// explicitly: its own art-proxy path (`/api/v1/library/art/…`, which [`proxy_local_art`] writes and
+/// which must survive a second pass unchanged) and a protocol-relative URL (`//cdn/…`, what GOG's and
+/// Microsoft's catalogs return — see [`abs_url`]). Mistaking either for a file would break the proxy
+/// round-trip or silently drop CDN art.
 pub fn is_local_art_path(v: &str) -> bool {
     if v.starts_with("http://") || v.starts_with("https://") || v.starts_with("data:") {
         return false;
     }
+    if v.starts_with("file://") {
+        return true;
+    }
     let b = v.as_bytes();
-    (b.len() >= 3 && b[1] == b':' && (b[2] == b'\\' || b[2] == b'/')) || v.starts_with("\\\\")
+    // Windows drive-absolute (`C:\…`, `C:/…`) or UNC (`\\server\share`).
+    if (b.len() >= 3 && b[1] == b':' && (b[2] == b'\\' || b[2] == b'/')) || v.starts_with("\\\\") {
+        return true;
+    }
+    // POSIX absolute, minus the host's own `/`-leading shapes (see the doc comment).
+    v.starts_with('/') && !v.starts_with("//") && !v.starts_with("/api/")
+}
+
+/// Turn a `file://` art value into a plain filesystem path, percent-decoding it. The kit emits
+/// properly encoded URLs (`file:///home/u/My%20Cover.jpg`); a raw path that happens to contain no
+/// `%` round-trips either way, which keeps hand-written plugin payloads working.
+///
+/// `file:///home/u/c.jpg` → `/home/u/c.jpg`; `file:///C:/covers/c.jpg` → `C:/covers/c.jpg` (Windows
+/// drive letters arrive after the empty authority's slash); a NON-empty authority
+/// (`file://nas/share/c.jpg`) is a UNC reference → `\\nas\share\c.jpg`. Anything without the prefix
+/// is returned untouched.
+fn file_url_to_path(v: &str) -> std::borrow::Cow<'_, str> {
+    use std::borrow::Cow;
+    let Some(rest) = v.strip_prefix("file://") else {
+        return Cow::Borrowed(v);
+    };
+    let decoded = percent_decode(rest);
+    match decoded.strip_prefix('/') {
+        // `file:///…` — the empty-authority form. A Windows drive letter (`/C:/…`) loses the slash;
+        // a POSIX path keeps it.
+        Some(after) if after.as_bytes().get(1) == Some(&b':') => Cow::Owned(after.to_string()),
+        Some(_) => Cow::Owned(decoded),
+        // `file://server/share/…` — a UNC path in URL clothing.
+        None => Cow::Owned(format!("\\\\{}", decoded.replace('/', "\\"))),
+    }
+}
+
+/// Percent-decode `%XX` escapes. Invalid escapes are left verbatim (a bare `%` in a real path is far
+/// likelier than a malformed URL from our own kit), and the result is only ever used as a path that
+/// must then exist as a regular file — so a wrong decode degrades to "no art", never to a wrong read.
+fn percent_decode(s: &str) -> String {
+    let b = s.as_bytes();
+    let mut out = Vec::with_capacity(b.len());
+    let mut i = 0;
+    while i < b.len() {
+        if b[i] == b'%' && i + 2 < b.len() {
+            let hex = |c: u8| (c as char).to_digit(16);
+            if let (Some(hi), Some(lo)) = (hex(b[i + 1]), hex(b[i + 2])) {
+                out.push((hi * 16 + lo) as u8);
+                i += 3;
+                continue;
+            }
+        }
+        out.push(b[i]);
+        i += 1;
+    }
+    String::from_utf8(out).unwrap_or_else(|_| s.to_string())
 }
 
 /// The filesystem roots the art proxy is allowed to read from.
@@ -192,6 +257,29 @@ fn art_roots() -> Vec<PathBuf> {
             roots.push(PathBuf::from(drive).join("Users"));
         }
     }
+    // POSIX: the user's home, which is the exact analogue of the Windows users base above — and
+    // where every launcher this host reads art from actually keeps it. Steam's
+    // `appcache/librarycache` and `userdata/<id>/config/grid`, Lutris's `coverart`/`banners` (both
+    // the `~/.local/share` and `~/.cache` copies), Heroic's caches, and all three Flatpak
+    // `~/.var/app/…` variants are under it.
+    //
+    // Needed because `is_local_art_path` now classifies POSIX absolute paths as local art (the
+    // extracted Lutris/Steam plugins emit them). Before that widening this list was legitimately
+    // empty here: the only local-art provider was Playnite, which is Windows-only, so nothing on a
+    // POSIX host was ever classified local and the confinement had nothing to confine. Leaving it
+    // empty now would not be "secure by default" — it would silently serve no plugin art at all.
+    //
+    // Breadth matches what Windows already ships, and it is not the load-bearing control: a value
+    // still has to carry an image extension, canonicalize to a real regular file inside a root,
+    // sit outside the host config dir, and CONTAIN image bytes. `PUNKTFUNK_LIBRARY_ART_ROOTS`
+    // narrows or relocates this for a library that lives elsewhere.
+    #[cfg(not(windows))]
+    if let Some(home) = std::env::var_os("HOME") {
+        let home = PathBuf::from(home);
+        if !home.as_os_str().is_empty() {
+            roots.push(home);
+        }
+    }
     roots
 }
 
@@ -306,15 +394,20 @@ pub fn validate_art_paths(art: &Artwork) -> Result<(), String> {
 ///
 /// This is the single place local art bytes are read — the mgmt art proxy and the GameStream
 /// `/appasset` proxy both land here — so the confinement holds for every caller.
+///
+/// A `file://` value is converted to a path FIRST ([`file_url_to_path`]), so the confinement check
+/// and the read see the same decoded path. Ordering matters: percent-decoding before
+/// canonicalization is what stops a `%2e%2e` escape being invisible to the traversal check.
 pub fn local_art_bytes(path: &str) -> Option<(Vec<u8>, String)> {
-    if !art_path_is_servable(path) {
+    let path = file_url_to_path(path);
+    if !art_path_is_servable(&path) {
         tracing::debug!(
-            path,
+            path = %path,
             "art proxy: refusing a path outside the allowed art roots"
         );
         return None;
     }
-    let p = std::path::Path::new(path);
+    let p = std::path::Path::new(&*path);
     let meta = std::fs::metadata(p).ok()?;
     if !meta.is_file() || meta.len() == 0 || meta.len() > 16 * 1024 * 1024 {
         return None;
@@ -358,9 +451,22 @@ pub fn proxy_local_art(id: &str, art: &mut Artwork) {
 /// `(bytes, content-type)`. Resolves the id against the host's OWN library. Blocking — call off the
 /// async runtime (e.g. `spawn_blocking`).
 pub fn fetch_box_art(id: &str) -> Option<(Vec<u8>, String)> {
-    // Steam's `Artwork` fields are now relative proxy paths (see `steam_art`) the *client* resolves
-    // against the host — meaningless to `fetch_image`, which expects an absolute URL. Resolve
-    // those kinds directly instead of going through the URL fields.
+    // Same resolution order as the management art proxy (WP1.2): the stored catalog first, for ANY
+    // id, so a library plugin's entries resolve without the warmer knowing its store.
+    if let Some(entry) = entry_for_library_id(id) {
+        return [
+            ArtKind::Portrait,
+            ArtKind::Header,
+            ArtKind::Hero,
+            ArtKind::Logo,
+        ]
+        .into_iter()
+        .filter_map(|kind| art_field(&entry.art, kind))
+        .find_map(|v| resolve_art_bytes(&v));
+    }
+    // Legacy in-host Steam scanner: its `Artwork` fields are relative proxy paths (see `steam_art`)
+    // the *client* resolves against the host — meaningless to `fetch_image`, which expects an
+    // absolute URL. Resolve those kinds directly instead of going through the URL fields.
     if let Some(appid) = id
         .strip_prefix("steam:")
         .and_then(|s| s.parse::<u32>().ok())
@@ -374,6 +480,7 @@ pub fn fetch_box_art(id: &str) -> Option<(Vec<u8>, String)> {
         .into_iter()
         .find_map(|kind| steam_art_bytes(appid, kind));
     }
+    // The remaining in-host scanners (heroic/lutris/epic/gog/xbox) carry absolute CDN URLs.
     let g = all_games().into_iter().find(|g| g.id == id)?;
     [g.art.portrait, g.art.header, g.art.hero, g.art.logo]
         .into_iter()
@@ -472,19 +579,60 @@ mod tests {
         assert!(fetch_image("data:image/png;base64,").is_none());
     }
 
+    /// The full accept/exclude table (WP1.2). The exclusions are the load-bearing half: two of the
+    /// three `/`-leading shapes here are emitted by the host ITSELF, so a POSIX rule that swallowed
+    /// them would break the proxy round-trip and silently drop CDN art.
     #[test]
     fn local_art_path_detection() {
         // Windows-shaped local paths a provider (Playnite) would store.
         assert!(is_local_art_path(r"C:\Users\me\cover.jpg"));
         assert!(is_local_art_path("C:/Users/me/cover.png"));
         assert!(is_local_art_path(r"\\nas\share\art.jpg"));
-        // URLs and the host proxy path are NOT local files.
+        // The `file://` plugin contract, on both platform shapes.
+        assert!(is_local_art_path("file:///home/u/covers/x.jpg"));
+        assert!(is_local_art_path("file:///C:/covers/x.jpg"));
+        // POSIX absolute — lutris covers, steam librarycache.
+        assert!(is_local_art_path("/home/u/.cache/lutris/coverart/x.jpg"));
+        assert!(is_local_art_path("/var/lib/steam/librarycache/570/h.jpg"));
+        // URLs are NOT local files.
         assert!(!is_local_art_path("https://cdn/x.jpg"));
         assert!(!is_local_art_path("http://host/x.jpg"));
         assert!(!is_local_art_path("data:image/png;base64,AAAA"));
+        // …nor is the host's OWN art-proxy path (it must survive a second `proxy_local_art` pass).
         assert!(!is_local_art_path(
             "/api/v1/library/art/custom:abc/portrait"
         ));
+        assert!(!is_local_art_path("/api/v1/library/art/steam:570/hero"));
+        // …nor a protocol-relative CDN URL (what GOG / the MS catalog return — see `abs_url`).
+        assert!(!is_local_art_path("//images.gog.com/abc_vertical.jpg"));
+        // A relative path is not absolute — nothing to serve.
+        assert!(!is_local_art_path("covers/x.jpg"));
+        assert!(!is_local_art_path(""));
+    }
+
+    #[test]
+    fn file_url_converts_to_a_path_and_percent_decodes() {
+        assert_eq!(file_url_to_path("file:///home/u/c.jpg"), "/home/u/c.jpg");
+        // Percent-encoded spaces — what a correct URL encoder emits for a real-world cover path.
+        assert_eq!(
+            file_url_to_path("file:///home/u/My%20Games/c%2Bx.jpg"),
+            "/home/u/My Games/c+x.jpg"
+        );
+        // Windows drive letters arrive after the empty authority's slash and lose it.
+        assert_eq!(
+            file_url_to_path("file:///C:/covers/c.jpg"),
+            "C:/covers/c.jpg"
+        );
+        // A non-empty authority is a UNC reference.
+        assert_eq!(
+            file_url_to_path("file://nas/share/c.jpg"),
+            r"\\nas\share\c.jpg"
+        );
+        // Non-`file://` values are returned untouched (bare paths still work).
+        assert_eq!(file_url_to_path("/home/u/c.jpg"), "/home/u/c.jpg");
+        assert_eq!(file_url_to_path(r"C:\c.jpg"), r"C:\c.jpg");
+        // A lone `%` (a legal path character) is not mangled into a decode failure.
+        assert_eq!(file_url_to_path("file:///home/100%.jpg"), "/home/100%.jpg");
     }
 
     #[test]
@@ -508,6 +656,46 @@ mod tests {
         );
     }
 
+    /// A POSIX local cover — the shape the lutris and steam plugins emit — is classified as local
+    /// art and rewritten to the proxy path. This is the case G4 blocked (Lutris art was inlined as
+    /// `data:` URLs and blew the 2 MB body limit at 49 covers).
+    ///
+    /// Deliberately free of filesystem and env: the READ half is confined, and lives in
+    /// `local_art_bytes_is_confined_and_image_only` so that only ONE test mutates
+    /// `PUNKTFUNK_LIBRARY_ART_ROOTS` (cargo runs these in parallel threads of one process, so two
+    /// would race).
+    #[test]
+    fn posix_local_art_is_classified_and_proxied() {
+        let path = if cfg!(windows) {
+            r"C:\covers\cover.jpg".to_string()
+        } else {
+            "/home/u/.cache/lutris/coverart/cover.jpg".to_string()
+        };
+        let mut art = Artwork {
+            portrait: Some(path.clone()),
+            hero: Some(format!("file://{path}")),
+            logo: Some("https://cdn/l.png".into()),
+            header: None,
+        };
+        assert!(is_local_art_path(&path));
+        proxy_local_art("lutris:42", &mut art);
+        assert_eq!(
+            art.portrait.as_deref(),
+            Some("/api/v1/library/art/lutris:42/portrait")
+        );
+        assert_eq!(
+            art.hero.as_deref(),
+            Some("/api/v1/library/art/lutris:42/hero"),
+            "a file:// value is local art too"
+        );
+        assert_eq!(art.logo.as_deref(), Some("https://cdn/l.png"));
+
+        // Re-running the rewrite is a no-op — the emitted proxy path must not be mistaken for a file.
+        let before = art.portrait.clone();
+        proxy_local_art("lutris:42", &mut art);
+        assert_eq!(art.portrait, before);
+    }
+
     const PNG: &[u8] = &[0x89, b'P', b'N', b'G', 0x0D, 0x0A, 0x1A, 0x0A, 0, 0, 0, 13];
 
     /// The art proxy reads bytes in the HOST process (LocalSystem on Windows) from a path the
@@ -562,6 +750,37 @@ mod tests {
         );
 
         assert!(local_art_bytes(dir.join("nope.png").to_str().unwrap()).is_none());
+        // A directory is not a servable cover — the proxy must never become a directory reader.
+        assert!(local_art_bytes(dir.to_str().unwrap()).is_none());
+
+        // The `file://` plugin contract reaches the SAME bytes through the SAME gate. This is the
+        // half that matters for the extracted scanners: they emit `file://` values, so if the
+        // conversion happened after the confinement check the check would be inspecting a string
+        // that is not the path being read.
+        let as_url = format!("file://{}", cover.to_str().unwrap());
+        assert_eq!(
+            local_art_bytes(&as_url)
+                .expect("file:// reads the same cover")
+                .0,
+            PNG
+        );
+        // …and a `file://` value is confined exactly like a bare one — no bypass by spelling.
+        assert!(
+            local_art_bytes(&format!("file://{}", elsewhere.to_str().unwrap())).is_none(),
+            "file:// must not escape the art roots"
+        );
+        // Percent-encoded traversal is decoded BEFORE canonicalization, so it cannot hide from the
+        // `..` check.
+        assert!(
+            local_art_bytes(&format!(
+                "file://{}/%2e%2e/{}/cover.png",
+                dir.to_str().unwrap(),
+                outside.file_name().unwrap().to_str().unwrap()
+            ))
+            .is_none(),
+            "percent-encoded traversal must be refused"
+        );
+
         // A UNC path is refused outright (outbound SMB auth coercion), before any filesystem hit.
         assert!(!art_path_is_servable(r"\\attacker\share\a.png"));
 

crates/punktfunk-host/src/library/custom.rs

@@ -28,6 +28,17 @@ pub struct CustomEntry {
     /// host-assigned `id` stays stable across reconciles. Present iff `provider` is.
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub external_id: Option<String>,
+    /// The **store this entry was claimed under** (D2), stamped by a `?store=`-qualified reconcile.
+    /// `None` = an unclaimed provider entry or a manual one, both of which surface as `custom`.
+    ///
+    /// Materialized onto the entry rather than looked up in [`Catalog::claims`] on every read so an
+    /// entry is self-describing: its id and its `store` badge derive from the entry alone, and stay
+    /// correct even while the claim map is being rewritten.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub store: Option<String>,
+    /// Whether this entry is a game or the launcher itself — see [`GameRole`].
+    #[serde(default, skip_serializing_if = "GameRole::is_game")]
+    pub role: GameRole,
     /// How to recognize this title's process once it is running (design §9) — the one thing a
     /// provider knows that the host cannot work out for itself.
     ///
@@ -53,6 +64,10 @@ pub struct CustomInput {
     /// Per-title prep/undo steps — commands run as the host user; operator-privileged config.
     #[serde(default)]
     pub prep: Vec<crate::hooks::PrepCmd>,
+    /// Whether this entry is a game or the launcher itself — see [`GameRole`]. A hand-added launcher
+    /// entry is legal (an operator may want a "Steam" tile without installing the steam plugin).
+    #[serde(default)]
+    pub role: GameRole,
     /// How to recognize this title's process — see [`CustomEntry::detect`].
     #[serde(default)]
     pub detect: DetectHint,
@@ -76,6 +91,10 @@ pub struct ProviderEntryInput {
     /// Per-title prep/undo steps — commands run as the host user; operator-privileged config.
     #[serde(default)]
     pub prep: Vec<crate::hooks::PrepCmd>,
+    /// Whether this entry is a game or the launcher itself — see [`GameRole`]. A library plugin
+    /// emits its `launchers(cfg)` entries with `role: "launcher"`.
+    #[serde(default)]
+    pub role: GameRole,
     /// How to recognize this title's process — see [`CustomEntry::detect`]. A provider that knows its
     /// titles' install directories (Playnite does) should send them: it is what lets a game launched
     /// through the provider's own client still end its session when the player quits.
@@ -101,10 +120,13 @@ impl From<CustomEntry> for GameEntry {
             .unwrap_or_default()
             .or_hint(&c.detect);
         GameEntry {
-            id: format!("custom:{}", c.id),
-            store: "custom".into(),
+            id: library_id_for(&c),
+            // A claimed entry wears its store's badge; everything else is `custom`. `provider` rides
+            // along either way, so attribution ("synced by the steam plugin") survives the claim.
+            store: c.store.clone().unwrap_or_else(|| "custom".into()),
             title: c.title,
             art: c.art,
+            role: c.role,
             launch: c.launch,
             provider: c.provider,
             detect,
@@ -122,42 +144,123 @@ fn custom_path() -> PathBuf {
     pf_paths::config_dir().join("library.json")
 }
 
-/// Load the custom entries (empty + non-fatal if the file is absent or malformed).
-pub fn load_custom() -> Vec<CustomEntry> {
+/// The persisted catalog (`library.json` **v2**): the entries plus the store-claim map (D2).
+#[derive(Debug, Default, Serialize, Deserialize)]
+pub struct Catalog {
+    #[serde(default)]
+    pub entries: Vec<CustomEntry>,
+    /// `store id → provider id`. One provider per store; a second claimant is refused (409).
+    ///
+    /// The map — not the entries — is the authority for a claim, which is exactly why it survives an
+    /// **empty reconcile**: a store the plugin legitimately owns can have zero installed titles, and
+    /// the built-in scanner it suppresses must stay suppressed anyway. Releasing is explicit
+    /// (`DELETE /library/provider/{p}`, or the plugin claiming a different store).
+    #[serde(default)]
+    pub claims: BTreeMap<String, String>,
+}
+
+/// What `library.json` may contain on disk. v1 was a bare array of entries; v2 is the [`Catalog`]
+/// object. Untagged, so an existing v1 file loads unchanged — and the host always WRITES v2, so the
+/// first mutation after an upgrade migrates the file in place with no separate migration step.
+#[derive(Deserialize)]
+#[serde(untagged)]
+enum LibraryFile {
+    V2(Catalog),
+    Legacy(Vec<CustomEntry>),
+}
+
+/// Load the whole catalog (default + non-fatal if the file is absent or malformed).
+pub fn load_catalog() -> Catalog {
     match std::fs::read_to_string(custom_path()) {
-        Ok(raw) => serde_json::from_str(&raw).unwrap_or_else(|e| {
-            tracing::warn!(error = %e, "library.json malformed — ignoring custom entries");
-            Vec::new()
-        }),
-        Err(_) => Vec::new(),
+        Ok(raw) => match serde_json::from_str::<LibraryFile>(&raw) {
+            Ok(LibraryFile::V2(c)) => c,
+            Ok(LibraryFile::Legacy(entries)) => Catalog {
+                entries,
+                claims: BTreeMap::new(),
+            },
+            Err(e) => {
+                tracing::warn!(error = %e, "library.json malformed — ignoring custom entries");
+                Catalog::default()
+            }
+        },
+        Err(_) => Catalog::default(),
     }
 }
 
-/// Serve a custom/provider entry's stored **local** art file for one [`ArtKind`] — the non-Steam
-/// branch of the art proxy (`GET /library/art/custom:<id>/<kind>`). `id` is the bare custom id (the
-/// `custom:` prefix already stripped by the handler). `None` if the entry is unknown, has no art of
-/// that kind, or that art value isn't a servable local file (e.g. an `http` URL the client fetches
-/// itself). Blocking IO — call off the async runtime.
-pub fn custom_local_art_bytes(id: &str, kind: ArtKind) -> Option<(Vec<u8>, String)> {
-    let entry = load_custom().into_iter().find(|e| e.id == id)?;
-    let field = match kind {
-        ArtKind::Portrait => entry.art.portrait,
-        ArtKind::Hero => entry.art.hero,
-        ArtKind::Logo => entry.art.logo,
-        ArtKind::Header => entry.art.header,
-    }?;
+/// Load just the entries — the read path every library surface uses.
+pub fn load_custom() -> Vec<CustomEntry> {
+    load_catalog().entries
+}
+
+/// The active store claims (`store → provider`). Read per library scan to suppress the built-in
+/// scanner a plugin has taken over (D2).
+pub fn claimed_stores() -> BTreeMap<String, String> {
+    load_catalog().claims
+}
+
+/// The library id a stored entry surfaces as. **The single source of truth for the mapping** —
+/// [`From<CustomEntry> for GameEntry`] and every id→entry lookup go through it, so the id scheme
+/// can't drift between the catalog, the art proxy and the launch resolver.
+///
+/// A **claimed** entry (D2) gets the deterministic `<store>:<external_id>` its built-in scanner used
+/// to produce — `steam:440`, `heroic:legendary:Quail` — so entry ids, GameStream FNV-1a app ids,
+/// client art caches and Moonlight pins all survive the migration to a plugin untouched. That is the
+/// whole point of the claim: extraction must be invisible to everything downstream. An unclaimed
+/// entry keeps the opaque host-assigned `custom:<id>`.
+pub(crate) fn library_id_for(e: &CustomEntry) -> String {
+    match (e.store.as_deref(), e.external_id.as_deref()) {
+        (Some(store), Some(external)) => format!("{store}:{external}"),
+        _ => format!("custom:{}", e.id),
+    }
+}
+
+/// The **source id** an entry is toggled by (WP2.6): its claimed store when it has one, else its
+/// provider id. `None` for a manual entry — the custom store is not a source and can never be
+/// switched off. Since the claimed store id, the provider id and the old scanner id are all the same
+/// string by construction, a user's existing disabled state carries over verbatim.
+pub(crate) fn source_id_for(e: &CustomEntry) -> Option<&str> {
+    e.store.as_deref().or(e.provider.as_deref())
+}
+
+/// The stored entry a full **library id** refers to, or `None`. The art proxy resolves *any* id this
+/// way before falling back to the legacy per-store branches (WP1.2), which is what lets a plugin's
+/// entries be served regardless of what their ids look like.
+pub fn entry_for_library_id(library_id: &str) -> Option<CustomEntry> {
+    load_custom()
+        .into_iter()
+        .find(|e| library_id_for(e) == library_id)
+}
+
+/// Serve a stored entry's **local** art file for one [`ArtKind`] — the `library.json` branch of the
+/// art proxy (`GET /library/art/<library id>/<kind>`). `None` if the id names no stored entry, it has
+/// no art of that kind, or that art value isn't a servable local file (e.g. an `http` URL the client
+/// fetches itself). Blocking IO — call off the async runtime.
+pub fn library_local_art_bytes(library_id: &str, kind: ArtKind) -> Option<(Vec<u8>, String)> {
+    let field = art_field(&entry_for_library_id(library_id)?.art, kind)?;
     is_local_art_path(&field)
         .then(|| local_art_bytes(&field))
         .flatten()
 }
 
-fn save_custom(entries: &[CustomEntry]) -> Result<()> {
+/// One [`Artwork`] field by kind — the tiny mapping the proxy and the box-art ladder share.
+pub(crate) fn art_field(art: &Artwork, kind: ArtKind) -> Option<String> {
+    match kind {
+        ArtKind::Portrait => art.portrait.clone(),
+        ArtKind::Hero => art.hero.clone(),
+        ArtKind::Logo => art.logo.clone(),
+        ArtKind::Header => art.header.clone(),
+    }
+}
+
+/// Persist the catalog in the **v2** shape (write-then-rename, restrictive perms). Every mutation
+/// path funnels through here, so a v1 file is upgraded by the first write.
+fn save_catalog(catalog: &Catalog) -> Result<()> {
     let dir = pf_paths::config_dir();
     // Owner-private dir (0700 / SYSTEM+Admins DACL) so a non-privileged local user can't plant a
     // library.json whose `prep`/`launch` commands the host would later execute — the same trust
     // boundary hooks.json and the mgmt token already use.
     pf_paths::create_private_dir(&dir).with_context(|| format!("create {}", dir.display()))?;
-    let json = serde_json::to_string_pretty(entries)?;
+    let json = serde_json::to_string_pretty(catalog)?;
     // Write-then-rename so a crash mid-write never truncates the catalog; `write_secret_file` gives
     // the temp file its restrictive perms (0600 / SYSTEM+Admins DACL) before the rename carries them
     // to the final path.
@@ -177,19 +280,26 @@ fn new_id(title: &str) -> String {
     hex::encode(&Sha256::digest(format!("{title}:{nanos}").as_bytes())[..6])
 }
 
-/// Outcome of a manual mutation against an id — distinguishes "no such entry" from "exists,
-/// but a provider owns it" (the mgmt layer maps the latter to 409, not 404).
+/// Outcome of a mutation — distinguishes "no such entry" from the two conflict cases the mgmt
+/// layer maps to 409 rather than 404.
 pub enum MutateOutcome<T> {
     Done(T),
     NotFound,
     /// The entry belongs to this provider — mutate it through the provider reconcile API
     /// (or remove the whole provider set); manual edits would be clobbered at the next sync.
     ProviderOwned(String),
+    /// The requested store claim is already held by a DIFFERENT provider (D2: one provider per
+    /// store). Refusing is the point — two plugins both emitting `steam:440` would collide on entry
+    /// ids, so the second claimant is told who holds it instead of silently taking over.
+    StoreClaimed {
+        store: String,
+        provider: String,
+    },
 }
 
 /// Create a custom (manual) entry, returning it with its assigned id.
 pub fn add_custom(input: CustomInput) -> Result<CustomEntry> {
-    let mut entries = load_custom();
+    let mut catalog = load_catalog();
     let entry = CustomEntry {
         id: new_id(&input.title),
         title: input.title,
@@ -198,11 +308,13 @@ pub fn add_custom(input: CustomInput) -> Result<CustomEntry> {
         prep: input.prep,
         provider: None,
         external_id: None,
+        store: None,
+        role: input.role,
         detect: input.detect,
         meta: input.meta,
     };
-    entries.push(entry.clone());
-    save_custom(&entries)?;
+    catalog.entries.push(entry.clone());
+    save_catalog(&catalog)?;
     emit_changed("manual");
     Ok(entry)
 }
@@ -210,8 +322,8 @@ pub fn add_custom(input: CustomInput) -> Result<CustomEntry> {
 /// Replace a manual entry's fields (id preserved). Provider-owned entries are refused —
 /// their state belongs to the provider's reconcile (RFC §8 ownership rule).
 pub fn update_custom(id: &str, input: CustomInput) -> Result<MutateOutcome<CustomEntry>> {
-    let mut entries = load_custom();
-    let Some(slot) = entries.iter_mut().find(|e| e.id == id) else {
+    let mut catalog = load_catalog();
+    let Some(slot) = catalog.entries.iter_mut().find(|e| e.id == id) else {
         return Ok(MutateOutcome::NotFound);
     };
     if let Some(provider) = &slot.provider {
@@ -221,25 +333,26 @@ pub fn update_custom(id: &str, input: CustomInput) -> Result<MutateOutcome<Custo
     slot.art = input.art;
     slot.launch = input.launch;
     slot.prep = input.prep;
+    slot.role = input.role;
     slot.detect = input.detect;
     slot.meta = input.meta;
     let updated = slot.clone();
-    save_custom(&entries)?;
+    save_catalog(&catalog)?;
     emit_changed("manual");
     Ok(MutateOutcome::Done(updated))
 }
 
 /// Delete a manual entry. Provider-owned entries are refused (see [`update_custom`]).
 pub fn delete_custom(id: &str) -> Result<MutateOutcome<()>> {
-    let mut entries = load_custom();
-    let Some(entry) = entries.iter().find(|e| e.id == id) else {
+    let mut catalog = load_catalog();
+    let Some(entry) = catalog.entries.iter().find(|e| e.id == id) else {
         return Ok(MutateOutcome::NotFound);
     };
     if let Some(provider) = &entry.provider {
         return Ok(MutateOutcome::ProviderOwned(provider.clone()));
     }
-    entries.retain(|e| e.id != id);
-    save_custom(&entries)?;
+    catalog.entries.retain(|e| e.id != id);
+    save_catalog(&catalog)?;
     emit_changed("manual");
     Ok(MutateOutcome::Done(()))
 }
@@ -258,7 +371,8 @@ pub fn delete_custom(id: &str) -> Result<MutateOutcome<()>> {
 /// copies of the very primitive the `/hooks` carve-out exists to withhold.
 ///
 /// Returns the field name for the error message, so a plugin author sees exactly what was refused.
-/// The other launch kinds (`steam_appid`, `epic`, `gog`, `aumid`, `lutris_id`, `heroic`) are all
+/// The other launch kinds (`steam_appid`, `steam_ui`, `launcher_ui`, `epic`, `gog`, `aumid`,
+/// `lutris_id`, `heroic`) are all
 /// host-resolved from a validated id and stay open to every lane — a provider plugin can still
 /// publish its whole catalogue, it just cannot hand the host a shell command to run.
 pub fn privileged_field(
@@ -293,6 +407,26 @@ pub fn validate_provider_name(provider: &str) -> Result<(), String> {
     }
 }
 
+/// Store claims become the **prefix of every claimed entry's library id**, so they are far more
+/// constrained than a provider name: no dots (an id is split on the first `:`, and a dotted store
+/// would read as a hostname in logs), and the two host-owned namespaces are off-limits — `custom` is
+/// the unclaimed-entry namespace and `manual` is the no-provider sentinel in `library.changed`.
+pub fn validate_store_claim(store: &str) -> Result<(), String> {
+    if store == "custom" || store == "manual" {
+        return Err(format!("store id `{store}` is reserved"));
+    }
+    let ok = !store.is_empty()
+        && store.len() <= 32
+        && store
+            .bytes()
+            .all(|b| b.is_ascii_lowercase() || b.is_ascii_digit() || matches!(b, b'-' | b'_'));
+    if ok {
+        Ok(())
+    } else {
+        Err("store id must be 1–32 chars of [a-z0-9_-]".into())
+    }
+}
+
 /// Validate a reconcile payload: non-empty titles and unique, non-empty external ids (the
 /// diff key — a duplicate would make ownership of the surviving entry ambiguous).
 pub fn validate_provider_payload(inputs: &[ProviderEntryInput]) -> Result<(), String> {
@@ -310,6 +444,40 @@ pub fn validate_provider_payload(inputs: &[ProviderEntryInput]) -> Result<(), St
                 e.external_id
             ));
         }
+        // Closed-vocabulary launch kinds are checked on the way IN as well as at launch time, so a
+        // plugin gets a 400 it can act on rather than a tile that silently refuses to start.
+        if let Some(launch) = &e.launch {
+            if launch.kind == "steam_ui" && !valid_steam_ui(&launch.value) {
+                return Err(format!(
+                    "entries[{i}]: `launch.value` for kind `steam_ui` must be `bigpicture` or `desktop`"
+                ));
+            }
+            // Refused rather than silently accepted, because the failure is otherwise invisible
+            // until a user clicks the tile: an unresolvable value yields no command at launch time.
+            if launch.kind == "launcher_ui" && !valid_launcher_ui(&launch.value) {
+                return Err(format!(
+                    "entries[{i}]: `launch.value` for kind `launcher_ui` names a launcher this host \
+                     cannot open (`{}`)",
+                    launch.value
+                ));
+            }
+        }
+        if let Some(marker) = &e.detect.env_marker {
+            if !valid_env_key(&marker.key) {
+                return Err(format!(
+                    "entries[{i}]: `detect.env_marker.key` must be 1–64 chars of [A-Za-z0-9_]"
+                ));
+            }
+            if marker
+                .value
+                .as_ref()
+                .is_some_and(|v| v.len() > MAX_ENV_VALUE)
+            {
+                return Err(format!(
+                    "entries[{i}]: `detect.env_marker.value` must be at most {MAX_ENV_VALUE} chars"
+                ));
+            }
+        }
     }
     Ok(())
 }
@@ -321,6 +489,7 @@ pub fn validate_provider_payload(inputs: &[ProviderEntryInput]) -> Result<(), St
 fn reconcile_entries(
     entries: &mut Vec<CustomEntry>,
     provider: &str,
+    store: Option<&str>,
     inputs: Vec<ProviderEntryInput>,
 ) -> Vec<CustomEntry> {
     // The provider's current entries, keyed by its own stable id.
@@ -345,6 +514,10 @@ fn reconcile_entries(
             prep: input.prep,
             provider: Some(provider.to_string()),
             external_id: Some(input.external_id),
+            // Stamping the claim per entry is what makes the surfaced id deterministic
+            // (`<store>:<external_id>`) — see `library_id_for`.
+            store: store.map(str::to_string),
+            role: input.role,
             detect: input.detect,
             meta: input.meta,
         });
@@ -354,43 +527,86 @@ fn reconcile_entries(
     result
 }
 
-/// Atomically replace `provider`'s entry set (RFC §8: `PUT /library/provider/{provider}`).
-/// The caller validates the name and payload first. Emits `library.changed` with the provider
-/// as the source.
+/// Atomically replace `provider`'s entry set (RFC §8: `PUT /library/provider/{provider}`), optionally
+/// under a **store claim** (D2: `?store=steam`). The caller validates the name and payload first.
+/// Emits `library.changed` with the provider as the source.
+///
+/// Claiming is idempotent for the holder and refused for anyone else. A provider holds at most one
+/// store, so claiming a new one releases whatever it held before — otherwise an abandoned claim would
+/// go on suppressing a built-in scanner with nothing to replace it.
 pub fn reconcile_provider(
     provider: &str,
+    store: Option<&str>,
     inputs: Vec<ProviderEntryInput>,
-) -> Result<Vec<CustomEntry>> {
-    let mut entries = load_custom();
-    let result = reconcile_entries(&mut entries, provider, inputs);
-    save_custom(&entries)?;
+) -> Result<MutateOutcome<Vec<CustomEntry>>> {
+    let mut catalog = load_catalog();
+    if let Some(store) = store {
+        if let Some(holder) = catalog.claims.get(store) {
+            if holder != provider {
+                return Ok(MutateOutcome::StoreClaimed {
+                    store: store.to_string(),
+                    provider: holder.clone(),
+                });
+            }
+        }
+        let previous: Vec<String> = catalog
+            .claims
+            .iter()
+            .filter(|(s, p)| p.as_str() == provider && s.as_str() != store)
+            .map(|(s, _)| s.clone())
+            .collect();
+        for stale in previous {
+            tracing::info!(provider, released = %stale, claimed = store, "library: provider moved its store claim");
+            catalog.claims.remove(&stale);
+        }
+        if catalog
+            .claims
+            .insert(store.to_string(), provider.to_string())
+            .is_none()
+        {
+            tracing::info!(provider, store, "library: store claimed by a provider");
+        }
+    }
+    let result = reconcile_entries(&mut catalog.entries, provider, store, inputs);
+    save_catalog(&catalog)?;
     emit_changed(provider);
-    Ok(result)
+    Ok(MutateOutcome::Done(result))
 }
 
-/// Remove every entry of `provider` (RFC §8: `DELETE /library/provider/{provider}` — the
-/// clean-uninstall path). Returns how many were removed; no event when nothing was.
+/// Remove every entry of `provider` **and release its store claim** (RFC §8:
+/// `DELETE /library/provider/{provider}` — the clean-uninstall path). Returns how many entries were
+/// removed; no event when nothing changed at all.
+///
+/// Releasing here — and only here — is what makes uninstalling a library plugin bring its built-in
+/// scanner straight back, with no restart and nothing to undo by hand.
 pub fn delete_provider(provider: &str) -> Result<usize> {
-    let mut entries = load_custom();
-    let before = entries.len();
-    entries.retain(|e| e.provider.as_deref() != Some(provider));
-    let removed = before - entries.len();
-    if removed > 0 {
-        save_custom(&entries)?;
+    let mut catalog = load_catalog();
+    let before = catalog.entries.len();
+    catalog
+        .entries
+        .retain(|e| e.provider.as_deref() != Some(provider));
+    let removed = before - catalog.entries.len();
+    let claims_before = catalog.claims.len();
+    catalog.claims.retain(|_, p| p != provider);
+    let released = claims_before - catalog.claims.len();
+    if removed > 0 || released > 0 {
+        if released > 0 {
+            tracing::info!(provider, released, "library: store claim released");
+        }
+        save_catalog(&catalog)?;
         emit_changed(provider);
     }
     Ok(removed)
 }
 
-/// The prep/undo steps for a library id — `custom:<id>` entries only (the other stores have no
+/// The prep/undo steps for a library id — any **stored** entry (the in-host scanners have no
 /// per-title config surface; a GameStream `apps.json` entry carries its own `prep` instead).
+///
+/// Resolved through [`entry_for_library_id`] rather than by stripping a `custom:` prefix, so a
+/// claimed entry's prep still runs: after extraction a `steam:440` entry is a stored one, and
+/// per-title prep is exactly the kind of thing an operator sets on a game they play.
 pub fn prep_for(library_id: &str) -> Vec<crate::hooks::PrepCmd> {
-    let Some(id) = library_id.strip_prefix("custom:") else {
-        return Vec::new();
-    };
-    load_custom()
-        .into_iter()
-        .find(|e| e.id == id)
+    entry_for_library_id(library_id)
         .map(|e| e.prep)
         .unwrap_or_default()
 }
@@ -403,13 +619,7 @@ fn emit_changed(source: &str) {
     });
 }
 
-/// A digits-only Steam appid: the sole client-influenced part of a Steam launch, validated before it
-/// is interpolated into any command / URI (so a client-sent id can never carry shell or URI syntax).
-/// Cross-platform — used by the Linux shell mapping ([`command_for`]) and the Windows spawn mapping
-/// ([`windows_launch_for`]).
-pub(crate) fn valid_steam_appid(value: &str) -> bool {
-    !value.is_empty() && value.bytes().all(|b| b.is_ascii_digit())
-}
+// `valid_steam_appid` moved to `launch.rs` (WP1.1) — it validates a launch value, not a store entry.
 
 #[cfg(test)]
 mod tests {
@@ -424,6 +634,8 @@ mod tests {
             prep: Vec::new(),
             provider: None,
             external_id: None,
+            store: None,
+            role: GameRole::Game,
             detect: DetectHint::default(),
             meta: GameMeta::default(),
         }
@@ -436,6 +648,7 @@ mod tests {
             art: Artwork::default(),
             launch: None,
             prep: Vec::new(),
+            role: GameRole::Game,
             detect: DetectHint::default(),
             meta: GameMeta::default(),
         }
@@ -457,6 +670,79 @@ mod tests {
         assert_eq!(g.meta.platform.as_deref(), Some("PS2"));
     }
 
+    /// D2's core promise: a **claimed** entry is indistinguishable from what the built-in scanner
+    /// produced. Same id, same store badge — plus the provider attribution the scanner never had.
+    #[test]
+    fn a_claimed_entry_reproduces_the_scanner_identity() {
+        let mut e = manual("host-assigned", "Portal 2");
+        e.provider = Some("steam".into());
+        e.external_id = Some("620".into());
+        e.store = Some("steam".into());
+        assert_eq!(library_id_for(&e), "steam:620");
+        let g: GameEntry = e.clone().into();
+        assert_eq!(g.id, "steam:620", "exactly what the scanner emitted");
+        assert_eq!(g.store, "steam", "the store badge, not `custom`");
+        assert_eq!(
+            g.provider.as_deref(),
+            Some("steam"),
+            "attribution rides along too"
+        );
+
+        // Unclaimed provider entries are untouched by any of this — rom-manager/playnite keep the
+        // opaque host id they have always had.
+        let mut u = manual("abc", "Chrono Trigger");
+        u.provider = Some("romm".into());
+        u.external_id = Some("rom-1".into());
+        assert_eq!(library_id_for(&u), "custom:abc");
+        assert_eq!(GameEntry::from(u).store, "custom");
+
+        // The source a toggle addresses: the claimed store when there is one, else the provider.
+        assert_eq!(source_id_for(&e), Some("steam"));
+        let mut r = manual("z", "T");
+        r.provider = Some("romm".into());
+        assert_eq!(source_id_for(&r), Some("romm"));
+        assert_eq!(
+            source_id_for(&manual("m", "Manual")),
+            None,
+            "never hideable"
+        );
+    }
+
+    /// A claimed entry keeps its `<store>:<external_id>` id across reconciles no matter what the
+    /// host-assigned id does — which is what keeps GameStream's FNV-1a app ids, client art caches
+    /// and Moonlight pins valid through the migration (the whole point of D2).
+    #[test]
+    fn claimed_ids_are_deterministic_across_reconciles() {
+        let mut entries = Vec::new();
+        let r1 = reconcile_entries(
+            &mut entries,
+            "steam",
+            Some("steam"),
+            vec![input("440", "Team Fortress 2"), input("620", "Portal 2")],
+        );
+        let ids: Vec<String> = r1.iter().map(library_id_for).collect();
+        assert_eq!(ids, ["steam:440", "steam:620"]);
+
+        // Re-sync with a renamed title and a new entry: the surfaced ids for surviving titles are
+        // byte-identical, and a brand-new title's id is derived, not random.
+        let r2 = reconcile_entries(
+            &mut entries,
+            "steam",
+            Some("steam"),
+            vec![
+                input("440", "Team Fortress 2 (2026)"),
+                input("70", "Half-Life"),
+            ],
+        );
+        let ids2: Vec<String> = r2.iter().map(library_id_for).collect();
+        assert_eq!(ids2, ["steam:440", "steam:70"]);
+
+        // Dropping the claim on a later reconcile reverts them to opaque custom ids — the entries
+        // are the same rows, so this is exactly the "plugin stopped claiming" degradation.
+        let r3 = reconcile_entries(&mut entries, "steam", None, vec![input("440", "TF2")]);
+        assert!(library_id_for(&r3[0]).starts_with("custom:"));
+    }
+
     /// The metadata contract on the wire and on disk: fields serialize FLAT (no `meta` nesting —
     /// clients and plugins see `platform` beside `title`), absent fields vanish entirely, and a
     /// pre-metadata `library.json` / payload still parses (all-optional).
@@ -505,6 +791,7 @@ mod tests {
         let r1 = reconcile_entries(
             &mut entries,
             "romm",
+            None,
             vec![input("rom-a", "Game A"), input("rom-b", "Game B")],
         );
         assert_eq!(r1.len(), 2);
@@ -516,6 +803,7 @@ mod tests {
         let r2 = reconcile_entries(
             &mut entries,
             "romm",
+            None,
             vec![input("rom-a", "Game A (v2)"), input("rom-c", "Game C")],
         );
         assert_eq!(r2.len(), 2);
@@ -534,6 +822,7 @@ mod tests {
         let r3 = reconcile_entries(
             &mut entries,
             "romm",
+            None,
             vec![input("rom-a", "Game A (v2)"), input("rom-c", "Game C")],
         );
         assert_eq!(
@@ -554,7 +843,7 @@ mod tests {
             .any(|e| e.id == "oth1" && e.provider.as_deref() == Some("itch")));
 
         // Empty payload = remove everything the provider owns (same as DELETE).
-        let r4 = reconcile_entries(&mut entries, "romm", Vec::new());
+        let r4 = reconcile_entries(&mut entries, "romm", None, Vec::new());
         assert!(r4.is_empty());
         assert_eq!(
             entries.len(),
@@ -563,6 +852,98 @@ mod tests {
         );
     }
 
+    /// `library.json` v1 (a bare array) must keep loading, and v2 (the claims object) must round
+    /// trip. This is the only migration in the whole program — get it wrong and an existing host
+    /// silently loses its manual entries on upgrade.
+    #[test]
+    fn v1_and_v2_library_files_both_load() {
+        // v1: exactly what a shipped host has on disk today.
+        let v1 = r#"[{"id":"abc","title":"Old Manual"}]"#;
+        let c = match serde_json::from_str::<LibraryFile>(v1).unwrap() {
+            LibraryFile::Legacy(entries) => Catalog {
+                entries,
+                claims: BTreeMap::new(),
+            },
+            LibraryFile::V2(_) => panic!("an array must not parse as v2"),
+        };
+        assert_eq!(c.entries.len(), 1);
+        assert_eq!(c.entries[0].title, "Old Manual");
+        assert!(c.claims.is_empty());
+
+        // v2, including a claim.
+        let v2 = r#"{"entries":[{"id":"abc","title":"New"}],"claims":{"steam":"steam"}}"#;
+        let c = match serde_json::from_str::<LibraryFile>(v2).unwrap() {
+            LibraryFile::V2(c) => c,
+            LibraryFile::Legacy(_) => panic!("an object must not parse as v1"),
+        };
+        assert_eq!(c.entries.len(), 1);
+        assert_eq!(c.claims.get("steam").map(String::as_str), Some("steam"));
+
+        // A v2 file with no claims key at all (what the first write after upgrade produces before
+        // anything is claimed) still loads.
+        let bare = r#"{"entries":[]}"#;
+        assert!(matches!(
+            serde_json::from_str::<LibraryFile>(bare).unwrap(),
+            LibraryFile::V2(_)
+        ));
+
+        // And what we WRITE is v2, so one mutation upgrades the file in place.
+        let written = serde_json::to_string(&Catalog::default()).unwrap();
+        assert!(written.contains("\"entries\""));
+        assert!(written.contains("\"claims\""));
+    }
+
+    #[test]
+    fn store_claim_validation() {
+        assert!(validate_store_claim("steam").is_ok());
+        assert!(validate_store_claim("epic-games").is_ok());
+        assert!(validate_store_claim("xbox_pc").is_ok());
+        // The two host-owned namespaces are off-limits.
+        assert!(validate_store_claim("custom").is_err());
+        assert!(validate_store_claim("manual").is_err());
+        assert!(validate_store_claim("").is_err());
+        assert!(validate_store_claim("Steam").is_err()); // no uppercase
+                                                         // A dot would read as a hostname in a log line and muddies the `store:id` split.
+        assert!(validate_store_claim("my.store").is_err());
+        assert!(validate_store_claim(&"s".repeat(33)).is_err());
+    }
+
+    /// The closed-vocabulary fields are rejected at the door, so a plugin gets a 400 rather than a
+    /// tile that silently refuses to launch.
+    #[test]
+    fn payload_validation_covers_the_new_closed_vocabularies() {
+        let with_launch = |kind: &str, value: &str| {
+            let mut i = input("a", "A");
+            i.launch = Some(LaunchSpec {
+                kind: kind.into(),
+                value: value.into(),
+            });
+            i
+        };
+        assert!(validate_provider_payload(&[with_launch("steam_ui", "bigpicture")]).is_ok());
+        assert!(validate_provider_payload(&[with_launch("steam_ui", "desktop")]).is_ok());
+        assert!(validate_provider_payload(&[with_launch("steam_ui", "gamepad")]).is_err());
+        assert!(validate_provider_payload(&[with_launch("steam_ui", "")]).is_err());
+        // Other kinds are unconstrained here (the host validates them per-kind at launch).
+        assert!(validate_provider_payload(&[with_launch("command", "anything")]).is_ok());
+
+        let with_env = |key: &str, value: Option<&str>| {
+            let mut i = input("a", "A");
+            i.detect.env_marker = Some(EnvMarker {
+                key: key.into(),
+                value: value.map(str::to_string),
+            });
+            i
+        };
+        assert!(validate_provider_payload(&[with_env("HEROIC_APP_NAME", Some("Quail"))]).is_ok());
+        assert!(validate_provider_payload(&[with_env("BAD-KEY", None)]).is_err());
+        assert!(validate_provider_payload(&[with_env("", None)]).is_err());
+        assert!(
+            validate_provider_payload(&[with_env("K", Some(&"x".repeat(MAX_ENV_VALUE + 1)))])
+                .is_err()
+        );
+    }
+
     /// The field-authority rule behind the 2026-08-05 review's H-1: exactly the two fields the host
     /// later hands to a shell are operator-only. Everything else — including every host-resolved
     /// launch kind — stays open, so a provider plugin can publish its whole catalogue.

crates/punktfunk-host/src/library/detect.rs

@@ -19,15 +19,34 @@
 use super::*;
 
 /// An environment variable a launcher stamps onto the game's process, identifying it.
-#[derive(Clone, Debug, PartialEq, Eq)]
+///
+/// Serializable because it is now half of the inbound [`DetectHint`] too (D3) — a library plugin
+/// that knows its launcher's marker (Heroic's `HEROIC_APP_NAME`, load-bearing under Proton) has to
+/// be able to say so, since after extraction the host no longer reads that launcher's files itself.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
 pub struct EnvMarker {
     /// The variable name (e.g. `HEROIC_GAME_ID`).
+    #[schema(example = "HEROIC_APP_NAME")]
     pub key: String,
     /// The exact value to require, when the launcher's value identifies *this* title. `None` matches
     /// the key's mere presence — only safe for launchers that run one game at a time.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub value: Option<String>,
 }
 
+/// The env-var name charset a hint may carry: `[A-Za-z0-9_]{1,64}`, POSIX-shaped. An out-of-charset
+/// key is not a real environment variable, so accepting one could only ever produce a matcher rule
+/// that never fires (or, with an absurd length, a needless per-process comparison cost).
+pub(crate) fn valid_env_key(key: &str) -> bool {
+    !key.is_empty()
+        && key.len() <= 64
+        && key.bytes().all(|b| b.is_ascii_alphanumeric() || b == b'_')
+}
+
+/// Longest env-var VALUE a hint may pin. Values are compared against every candidate process's
+/// environment, so an unbounded one is a (small) DoS lever and never a legitimate game id.
+pub(crate) const MAX_ENV_VALUE: usize = 256;
+
 /// The signals that identify a launched title's process(es). Every field is optional and
 /// independent; an all-`None` spec means "this title can't be tracked" (the lease degrades to
 /// [`crate::gamelease::LeaseKind::Untracked`] and both lifetime behaviors stay inert for it).
@@ -115,6 +134,11 @@ impl DetectSpec {
         self.install_dir = self.install_dir.or(from.install_dir);
         self.exe = self.exe.or(from.exe);
         self.process_name = self.process_name.or(from.process_name);
+        // D3: the two store-derived signals are fillable from a hint now that the store may live in
+        // a plugin. Same rule as the other three — the host's own finding wins where it has one,
+        // which for a provider entry is moot (the host scanned nothing for it).
+        self.steam_appid = self.steam_appid.or(from.steam_appid);
+        self.env_marker = self.env_marker.or(from.env_marker);
         self
     }
 }
@@ -143,12 +167,31 @@ pub struct DetectHint {
     /// — see [`DetectSpec::process_name`].
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub process_name: Option<String>,
+    /// The Steam appid, for a title Steam itself installed (D3). On Linux this is the **sharpest**
+    /// signal that exists — Steam wraps every launch, native or Proton, in
+    /// `reaper SteamLaunch AppId=<appid>`, whose lifetime is exactly the game's — so without it a
+    /// steam plugin's lease tracking would degrade from reaper-exact to install-dir prefix matching.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub steam_appid: Option<u32>,
+    /// A launcher-stamped environment marker (D3) — see [`EnvMarker`].
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub env_marker: Option<EnvMarker>,
 }
 
 impl DetectHint {
     /// Whether the hint says anything at all (all-empty is treated as absent).
     pub fn is_empty(&self) -> bool {
-        self.trimmed().is_none()
+        self.trimmed().is_none() && self.steam_appid.is_none() && self.env_marker().is_none()
+    }
+
+    /// The env marker, if it is well-formed. A malformed one is dropped rather than rejected, for
+    /// the same reason a blank `install_dir` is: hint fields are hand-writable plugin input, and the
+    /// matcher must never be handed a rule it can't honour.
+    fn env_marker(&self) -> Option<&EnvMarker> {
+        self.env_marker
+            .as_ref()
+            .filter(|m| valid_env_key(&m.key))
+            .filter(|m| m.value.as_ref().is_none_or(|v| v.len() <= MAX_ENV_VALUE))
     }
 
     /// The hint with blank fields dropped, or `None` if nothing is left. Console text inputs and
@@ -166,14 +209,13 @@ impl DetectHint {
 /// A provider's hint becomes a spec — the one inbound path into [`DetectSpec`].
 impl From<&DetectHint> for DetectSpec {
     fn from(h: &DetectHint) -> Self {
-        let Some((install_dir, exe, process_name)) = h.trimmed() else {
-            return Self::default();
-        };
+        let (install_dir, exe, process_name) = h.trimmed().unwrap_or((None, None, None));
         Self {
             install_dir: install_dir.map(PathBuf::from),
             exe: exe.map(PathBuf::from),
             process_name: process_name.map(str::to_string),
-            ..Default::default()
+            steam_appid: h.steam_appid,
+            env_marker: h.env_marker().cloned(),
         }
     }
 }
@@ -273,6 +315,7 @@ mod tests {
             install_dir: Some("".into()),
             exe: Some("   ".into()),
             process_name: Some("\t".into()),
+            ..Default::default()
         };
         assert!(blank.is_empty());
         assert!(DetectSpec::from(&blank).is_empty(), "nothing to match on");
@@ -281,6 +324,7 @@ mod tests {
             install_dir: Some("  /games/quail  ".into()),
             exe: None,
             process_name: Some("quail".into()),
+            ..Default::default()
         };
         assert!(!hint.is_empty());
         let spec = DetectSpec::from(&hint);
@@ -299,6 +343,7 @@ mod tests {
             install_dir: Some("/games/wrong".into()),
             exe: Some("/games/real/run".into()),
             process_name: None,
+            ..Default::default()
         };
         let merged = found.or_hint(&hint);
         assert_eq!(
@@ -317,6 +362,74 @@ mod tests {
             .is_empty());
     }
 
+    /// D3: the two store-derived signals now ride the hint, because after extraction the host no
+    /// longer reads Steam's or Heroic's files itself. Without them a plugin's lease tracking would
+    /// silently degrade — reaper-exact to dir-prefix on Linux Steam, and gone entirely for Heroic
+    /// under Proton, where the env marker is the only thing that works.
+    #[test]
+    fn a_hint_can_carry_the_store_derived_signals() {
+        let hint = DetectHint {
+            steam_appid: Some(440),
+            env_marker: Some(EnvMarker {
+                key: "HEROIC_APP_NAME".into(),
+                value: Some("Quail".into()),
+            }),
+            ..Default::default()
+        };
+        assert!(!hint.is_empty(), "either field alone is a real hint");
+        let spec = DetectSpec::from(&hint);
+        assert_eq!(spec.steam_appid, Some(440));
+        assert_eq!(spec.env_marker.as_ref().unwrap().key, "HEROIC_APP_NAME");
+
+        // A steam_appid on its own is enough to be trackable.
+        let only_appid = DetectHint {
+            steam_appid: Some(620),
+            ..Default::default()
+        };
+        assert!(!only_appid.is_empty());
+        assert!(!DetectSpec::from(&only_appid).is_empty());
+
+        // The host's own finding still wins where it has one (unchanged rule).
+        let found = DetectSpec::steam(70);
+        assert_eq!(found.or_hint(&hint).steam_appid, Some(70));
+        // …but a field the host had nothing for is filled in.
+        assert_eq!(
+            DetectSpec::dir("/games/x")
+                .or_hint(&hint)
+                .env_marker
+                .unwrap()
+                .key,
+            "HEROIC_APP_NAME"
+        );
+    }
+
+    /// A malformed marker is DROPPED, not honoured — same posture as a blank `install_dir`. The
+    /// matcher must never be handed a rule it cannot evaluate, and these values reach a code path
+    /// that can end processes.
+    #[test]
+    fn a_malformed_env_marker_says_nothing() {
+        let bad = |key: &str, value: Option<String>| DetectHint {
+            env_marker: Some(EnvMarker {
+                key: key.into(),
+                value,
+            }),
+            ..Default::default()
+        };
+        assert!(bad("", None).is_empty());
+        assert!(bad("HAS-DASH", None).is_empty(), "not a POSIX env name");
+        assert!(bad("HAS SPACE", None).is_empty());
+        assert!(bad(&"K".repeat(65), None).is_empty(), "over the key cap");
+        assert!(
+            bad("K", Some("v".repeat(MAX_ENV_VALUE + 1))).is_empty(),
+            "over the value cap"
+        );
+        // …and a well-formed one at exactly the caps is kept.
+        assert!(!bad(&"K".repeat(64), Some("v".repeat(MAX_ENV_VALUE))).is_empty());
+        assert!(DetectSpec::from(&bad("HAS-DASH", None))
+            .env_marker
+            .is_none());
+    }
+
     #[test]
     fn first_token_handles_quotes_and_spaces() {
         assert_eq!(

crates/punktfunk-host/src/library/epic.rs

@@ -100,6 +100,7 @@ fn epic_entry(
     };
     Some(GameEntry {
         provider: None,
+        role: GameRole::Game,
         meta: GameMeta::pc(),
         id: format!("epic:{app_name}"),
         store: "epic".into(),
@@ -186,25 +187,8 @@ fn epic_art_index(catcache: &Path) -> std::collections::HashMap<String, Artwork>
     map
 }
 
-/// Build the `com.epicgames.launcher://` launch URI from a stored launch value — the triple
-/// `<namespace>:<catalogItemId>:<appName>` (colons URL-encoded), or a bare `<appName>` fallback.
-/// Each part is charset-validated (host-derived, but belt-and-suspenders) so no shell/URI injection.
-#[cfg(windows)]
-pub(crate) fn epic_launch_uri(value: &str) -> Option<String> {
-    let ok = |s: &str| {
-        !s.is_empty()
-            && s.bytes()
-                .all(|b| b.is_ascii_alphanumeric() || matches!(b, b'.' | b'_' | b'-'))
-    };
-    let inner = match value.split(':').collect::<Vec<_>>().as_slice() {
-        [ns, cat, app] if ok(ns) && ok(cat) && ok(app) => format!("{ns}%3A{cat}%3A{app}"),
-        [app] if ok(app) => (*app).to_string(),
-        _ => return None,
-    };
-    Some(format!(
-        "com.epicgames.launcher://apps/{inner}?action=launch&silent=true"
-    ))
-}
+// The `epic` launch mapping (`epic_launch_uri`) lives in `launch.rs` (WP1.1) — this module
+// enumerates, it does not launch.
 
 #[cfg(test)]
 mod tests {
@@ -236,19 +220,4 @@ mod tests {
         assert!(epic_entry(&gone, &empty).is_none());
         std::fs::remove_dir_all(&dir).ok();
     }
-
-    #[cfg(windows)]
-    #[test]
-    fn epic_launch_uri_triple_bare_and_guard() {
-        assert_eq!(
-            epic_launch_uri("fn:abc:Fortnite").as_deref(),
-            Some("com.epicgames.launcher://apps/fn%3Aabc%3AFortnite?action=launch&silent=true")
-        );
-        assert_eq!(
-            epic_launch_uri("Fortnite").as_deref(),
-            Some("com.epicgames.launcher://apps/Fortnite?action=launch&silent=true")
-        );
-        assert!(epic_launch_uri("bad part:x:y").is_none()); // a space → rejected
-        assert!(epic_launch_uri("").is_none());
-    }
 }

crates/punktfunk-host/src/library/gog.rs

@@ -57,6 +57,7 @@ fn gog_games() -> Vec<GameEntry> {
         let detect = DetectSpec::exe(&exe).with_dir(&path);
         out.push(GameEntry {
             provider: None,
+            role: GameRole::Game,
             meta: GameMeta::pc(),
             id,
             store: "gog".into(),
@@ -133,38 +134,13 @@ fn gog_play_task(install: &str, id: &str) -> Option<(String, String, String)> {
     ))
 }
 
-/// Build the spawn `(command line, working dir)` for a `gog` launch value (`exe \t args \t workdir`,
-/// all host-resolved from the operator's own disk). Direct exe — no shell, no Galaxy.
-#[cfg(windows)]
-pub(crate) fn gog_spawn(value: &str) -> Option<(String, Option<PathBuf>)> {
-    let mut parts = value.split('\t');
-    let exe = parts.next().filter(|s| !s.is_empty())?;
-    let args = parts.next().unwrap_or("");
-    let workdir = parts.next().filter(|s| !s.is_empty()).map(PathBuf::from);
-    let cmdline = if args.trim().is_empty() {
-        format!("\"{exe}\"")
-    } else {
-        format!("\"{exe}\" {args}")
-    };
-    Some((cmdline, workdir))
-}
+// The `gog` launch mapping (`gog_spawn`) lives in `launch.rs` (WP1.1) — this module enumerates and
+// resolves the spawn triple off disk, but turning that triple into a command line is launch-side.
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
-    #[cfg(windows)]
-    #[test]
-    fn gog_spawn_parses_and_guards() {
-        let (cmd, wd) = gog_spawn("C:\\Games\\W3\\witcher3.exe\t--skip\tC:\\Games\\W3").unwrap();
-        assert_eq!(cmd, "\"C:\\Games\\W3\\witcher3.exe\" --skip");
-        assert_eq!(wd, Some(std::path::PathBuf::from("C:\\Games\\W3")));
-        let (cmd2, wd2) = gog_spawn("C:\\g.exe").unwrap();
-        assert_eq!(cmd2, "\"C:\\g.exe\"");
-        assert!(wd2.is_none());
-        assert!(gog_spawn("").is_none());
-    }
-
     #[cfg(windows)]
     #[test]
     fn gog_play_task_picks_primary_filetask() {

crates/punktfunk-host/src/library/heroic.rs

@@ -109,6 +109,7 @@ fn heroic_games(path: &Path, runner: &str, key: &str) -> anyhow::Result<Vec<Game
         };
         games.push(GameEntry {
             provider: None,
+            role: GameRole::Game,
             meta: GameMeta::pc(),
             id: format!("heroic:{runner}:{app_name}"),
             store: "heroic".into(),
@@ -128,48 +129,8 @@ fn heroic_games(path: &Path, runner: &str, key: &str) -> anyhow::Result<Vec<Game
     Ok(games)
 }
 
-/// Map a `heroic` LaunchSpec value (`<runner>:<appName>`) to the Heroic launch command, run nested in
-/// gamescope. The host owns this mapping; the client only ever sends the id. CAVEAT: Heroic is a
-/// single-instance Electron app — in a fresh per-session gamescope it boots, launches the game (which
-/// renders into that gamescope) and stays hidden via `--no-gui`; but if a Heroic GUI is ALREADY
-/// running on the box, the spawned process forwards the URI and exits, which would tear the session
-/// down. The validated path is the fresh-session case; needs live confirmation on a box with Heroic.
-#[cfg(target_os = "linux")]
-pub(crate) fn heroic_command(value: &str) -> Option<String> {
-    let (runner, app) = value.split_once(':')?;
-    if !matches!(runner, "legendary" | "gog" | "nile") {
-        return None;
-    }
-    // appName charset (Epic alnum, GOG digits, Amazon alnum) — keep the URI a single safe token.
-    if app.is_empty()
-        || !app
-            .bytes()
-            .all(|b| b.is_ascii_alphanumeric() || matches!(b, b'.' | b'_' | b'-'))
-    {
-        return None;
-    }
-    let prefix = heroic_launch_prefix()?;
-    // No quotes: gamescope spawns the app by `split_whitespace()`, and the URI has no spaces (appName
-    // is validated above) so it stays a single argv token; `&` is fine (exec'd, not shell-parsed).
-    Some(format!(
-        "{prefix} --no-gui heroic://launch?appName={app}&runner={runner}"
-    ))
-}
-
-/// How to invoke Heroic: the native `heroic` binary if on `PATH`, else the Flatpak app if its data
-/// root is present. `None` ⇒ Heroic not found, so no launch command.
-#[cfg(target_os = "linux")]
-fn heroic_launch_prefix() -> Option<String> {
-    let on_path = std::env::var_os("PATH")
-        .is_some_and(|paths| std::env::split_paths(&paths).any(|d| d.join("heroic").is_file()));
-    if on_path {
-        return Some("heroic".into());
-    }
-    let flatpak = std::env::var_os("HOME")
-        .map(PathBuf::from)
-        .is_some_and(|h| h.join(".var/app/com.heroicgameslauncher.hgl").is_dir());
-    flatpak.then(|| "flatpak run com.heroicgameslauncher.hgl".into())
-}
+// The `heroic` launch mapping (`heroic_command` + its launcher-prefix probe) lives in `launch.rs`
+// (WP1.1) — this module enumerates, it does not launch.
 
 #[cfg(test)]
 mod tests {

crates/punktfunk-host/src/library/launch.rs

@@ -1,12 +1,14 @@
 //! Title launch: resolve a library id / raw command into an executable command line (per-store +
 //! per-OS), and the gamescope-session launch helpers. Split out of the `library` facade (plan §W5).
+//!
+//! This module owns the **whole launch side** of the library: the `kind` vocabulary, its per-kind
+//! charset validators, and the per-OS resolvers. That split is deliberate and load-bearing — the
+//! scanner modules beside it do *enumeration only*, so they can be lifted out into library plugins
+//! without taking any launch logic with them (design/library-scanner-plugins.md D1: a client sends
+//! only an entry id and the host resolves the [`LaunchSpec`] it holds, which stays true whether the
+//! entry was enumerated in-process or reconciled in by a plugin).
 
-use super::custom::valid_steam_appid;
-#[cfg(target_os = "linux")]
-use super::heroic::heroic_command;
 use super::*;
-#[cfg(windows)]
-use super::{epic::epic_launch_uri, gog::gog_spawn};
 
 /// Everything a session needs about the title it is launching, resolved in **one** library scan:
 /// what to run, what to call it, and how to recognize it once it is running.
@@ -84,6 +86,25 @@ fn command_for(spec: &LaunchSpec) -> Option<String> {
         // Heroic: `<runner>:<appName>` → the validated heroic://launch command (see heroic_command).
         #[cfg(target_os = "linux")]
         "heroic" => heroic_command(&spec.value),
+        // A launcher entry (D4): open the Steam client itself, in Big Picture or on the desktop.
+        // Nested in gamescope this is the SteamOS game-mode shape.
+        "steam_ui" => match spec.value.as_str() {
+            "bigpicture" => Some("steam -gamepadui".into()),
+            "desktop" => Some("steam".into()),
+            _ => None,
+        },
+        // The other launchers' own UIs (D4). The host builds the command — a plugin only names
+        // which launcher — so no shell string ever crosses the wire.
+        #[cfg(target_os = "linux")]
+        "launcher_ui" => match spec.value.as_str() {
+            // The same resolution the `heroic` game launches use (native binary, else Flatpak), just
+            // without `--no-gui` and without a URI: that opens Heroic's window, which IS the tile.
+            "heroic" => heroic_launch_prefix(),
+            // Bare `lutris` opens the Lutris window; with a `lutris:rungameid/…` URI it launches a
+            // game instead (the `lutris_id` kind above).
+            "lutris" => Some("lutris".into()),
+            _ => None,
+        },
         // Trusted: the command comes from the host's own custom store, never the client.
         "command" => (!spec.value.trim().is_empty()).then(|| spec.value.clone()),
         _ => None,
@@ -138,6 +159,21 @@ fn windows_launch_for(spec: &LaunchSpec) -> Option<(String, Option<std::path::Pa
             };
             Some((cmdline, None))
         }
+        // A launcher entry (D4): open the Steam client's own UI. Same Steam.exe-then-explorer ladder
+        // as `steam_appid`, and the URI is one of exactly two host-owned literals — nothing from the
+        // entry is interpolated at all.
+        "steam_ui" => {
+            let uri = match spec.value.as_str() {
+                "bigpicture" => "steam://open/bigpicture",
+                "desktop" => "steam://open/main",
+                _ => return None,
+            };
+            let cmdline = match steam_exe() {
+                Some(exe) => format!("\"{}\" \"{uri}\"", exe.display()),
+                None => format!("explorer.exe \"{uri}\""),
+            };
+            Some((cmdline, None))
+        }
         // Epic: open the (host-built, validated) com.epicgames.launcher:// URI via explorer.exe — a
         // concrete EXE that resolves the registered protocol handler as the user; the URI is a single
         // argv element (no shell, no cmd /c). Same pattern as the steam explorer fallback.
@@ -191,6 +227,152 @@ fn steam_exe() -> Option<std::path::PathBuf> {
     None
 }
 
+// ------------------------------------------------------- per-kind launch values (host-owned ABI)
+//
+// Each helper below turns a store's launch VALUE — the only part a scanner (or, after extraction, a
+// library plugin) supplies — into the URI/command line the host actually runs. They live here rather
+// than beside the enumeration that produces the value because the host keeps owning URI construction
+// and spawning no matter where the enumeration came from (D1). Every one of them is total and
+// validating: an unparseable or hostile value yields `None`, never a partially-interpolated command.
+
+/// A digits-only Steam appid: the sole client-influenced part of a Steam launch, validated before it
+/// is interpolated into any command / URI (so a client-sent id can never carry shell or URI syntax).
+/// Cross-platform — used by the Linux shell mapping ([`command_for`]) and the Windows spawn mapping
+/// ([`windows_launch_for`]).
+///
+/// Also accepts the 64-bit non-Steam-shortcut game id ([`shortcut_gameid`]), which is likewise
+/// digits — the two share the `steam_appid` kind precisely because `rungameid` takes either.
+pub(crate) fn valid_steam_appid(value: &str) -> bool {
+    !value.is_empty() && value.bytes().all(|b| b.is_ascii_digit())
+}
+
+/// The 64-bit game id `steam://rungameid/` needs to launch a non-Steam shortcut: high dword = the
+/// 32-bit shortcut appid, low dword = the shortcut marker `0x0200_0000`. (Handing `rungameid` the
+/// bare 32-bit appid does not launch a shortcut — it must be this composed id.)
+pub(crate) fn shortcut_gameid(appid: u32) -> u64 {
+    ((appid as u64) << 32) | 0x0200_0000
+}
+
+/// The `steam_ui` launch values (D4) — which Steam UI a launcher entry opens. A closed two-value
+/// enum, validated on the way IN (the reconcile payload) as well as on the way out, so an entry can
+/// never carry a third value that silently resolves to nothing at launch time.
+pub(crate) fn valid_steam_ui(value: &str) -> bool {
+    matches!(value, "bigpicture" | "desktop")
+}
+
+/// The launcher UIs **this host** can open, as `launcher_ui` values (D4).
+///
+/// One kind for every launcher but Steam, rather than one kind each: they all have exactly a single
+/// UI to open, so the value is just which launcher. Steam keeps its own [`valid_steam_ui`] kind
+/// because it has two (Big Picture and the desktop client), which is a genuinely different choice.
+///
+/// Platform-gated, because a value naming a launcher this OS cannot run is not a tile that merely
+/// looks odd — it is one that fails at launch. Validated inbound too, so a plugin gets a 400 it can
+/// act on instead of publishing a dead entry.
+///
+/// **Why a typed kind at all**, when design D4 originally said non-Steam launchers would ride the
+/// `command` kind: the 2026-08-05 review made `launch.kind = "command"` operator-only (it is handed
+/// to a shell), so a plugin publishing one is refused. A typed kind keeps D1's rule intact — the
+/// plugin supplies a validated *value*, the host builds the command — and is the only way a scanner
+/// plugin can offer a launcher tile at all.
+fn launcher_ui_stores() -> &'static [&'static str] {
+    #[cfg(target_os = "linux")]
+    {
+        &["heroic", "lutris"]
+    }
+    // Windows launchers (Epic, GOG Galaxy, the Xbox app) are not wired yet — each needs its own
+    // verified activation, and an unverified guess would ship a tile that does nothing.
+    #[cfg(not(target_os = "linux"))]
+    {
+        &[]
+    }
+}
+
+/// Is this a `launcher_ui` value this host can resolve?
+pub(crate) fn valid_launcher_ui(value: &str) -> bool {
+    launcher_ui_stores().contains(&value)
+}
+
+/// Map a `heroic` LaunchSpec value (`<runner>:<appName>`) to the Heroic launch command, run nested in
+/// gamescope. The host owns this mapping; the client only ever sends the id. CAVEAT: Heroic is a
+/// single-instance Electron app — in a fresh per-session gamescope it boots, launches the game (which
+/// renders into that gamescope) and stays hidden via `--no-gui`; but if a Heroic GUI is ALREADY
+/// running on the box, the spawned process forwards the URI and exits, which would tear the session
+/// down. The validated path is the fresh-session case; needs live confirmation on a box with Heroic.
+#[cfg(target_os = "linux")]
+pub(crate) fn heroic_command(value: &str) -> Option<String> {
+    let (runner, app) = value.split_once(':')?;
+    if !matches!(runner, "legendary" | "gog" | "nile") {
+        return None;
+    }
+    // appName charset (Epic alnum, GOG digits, Amazon alnum) — keep the URI a single safe token.
+    if app.is_empty()
+        || !app
+            .bytes()
+            .all(|b| b.is_ascii_alphanumeric() || matches!(b, b'.' | b'_' | b'-'))
+    {
+        return None;
+    }
+    let prefix = heroic_launch_prefix()?;
+    // No quotes: gamescope spawns the app by `split_whitespace()`, and the URI has no spaces (appName
+    // is validated above) so it stays a single argv token; `&` is fine (exec'd, not shell-parsed).
+    Some(format!(
+        "{prefix} --no-gui heroic://launch?appName={app}&runner={runner}"
+    ))
+}
+
+/// How to invoke Heroic: the native `heroic` binary if on `PATH`, else the Flatpak app if its data
+/// root is present. `None` ⇒ Heroic not found, so no launch command.
+#[cfg(target_os = "linux")]
+fn heroic_launch_prefix() -> Option<String> {
+    let on_path = std::env::var_os("PATH")
+        .is_some_and(|paths| std::env::split_paths(&paths).any(|d| d.join("heroic").is_file()));
+    if on_path {
+        return Some("heroic".into());
+    }
+    let flatpak = std::env::var_os("HOME")
+        .map(PathBuf::from)
+        .is_some_and(|h| h.join(".var/app/com.heroicgameslauncher.hgl").is_dir());
+    flatpak.then(|| "flatpak run com.heroicgameslauncher.hgl".into())
+}
+
+/// Map an `epic` LaunchSpec value to the Epic Games Launcher URI. The value is either the full
+/// `<namespace>:<catalogItemId>:<appName>` triple (what the manifests carry) or a bare `appName`;
+/// every part is charset-checked so the URI stays one safe argv token.
+#[cfg(windows)]
+pub(crate) fn epic_launch_uri(value: &str) -> Option<String> {
+    let ok = |s: &str| {
+        !s.is_empty()
+            && s.bytes()
+                .all(|b| b.is_ascii_alphanumeric() || matches!(b, b'.' | b'_' | b'-'))
+    };
+    let inner = match value.split(':').collect::<Vec<_>>().as_slice() {
+        [ns, cat, app] if ok(ns) && ok(cat) && ok(app) => format!("{ns}%3A{cat}%3A{app}"),
+        [app] if ok(app) => (*app).to_string(),
+        _ => return None,
+    };
+    Some(format!(
+        "com.epicgames.launcher://apps/{inner}?action=launch&silent=true"
+    ))
+}
+
+/// Map a `gog` LaunchSpec value — the tab-separated `exe \t args \t workdir` spawn triple the scanner
+/// derived from `goggame-<id>.info` — to a `(command line, working dir)`. GOG games are spawned
+/// directly (no Galaxy), so the exe is quoted and the arguments ride verbatim.
+#[cfg(windows)]
+pub(crate) fn gog_spawn(value: &str) -> Option<(String, Option<PathBuf>)> {
+    let mut parts = value.split('\t');
+    let exe = parts.next().filter(|s| !s.is_empty())?;
+    let args = parts.next().unwrap_or("");
+    let workdir = parts.next().filter(|s| !s.is_empty()).map(PathBuf::from);
+    let cmdline = if args.trim().is_empty() {
+        format!("\"{exe}\"")
+    } else {
+        format!("\"{exe}\" {args}")
+    };
+    Some((cmdline, workdir))
+}
+
 /// Launch a GameStream `apps.json` command (operator-typed, trusted — never client-set) into the
 /// interactive Windows user session, AFTER capture is up (the host is SYSTEM). The Linux paths go
 /// through the compositor-aware [`launch_session_command`] instead.
@@ -360,6 +542,145 @@ mod tests {
         }
     }
 
+    /// The `steam_ui` launcher kind (D4): a closed two-value enum, mapped to the Steam client's own
+    /// UI on each OS. Nothing from the entry is interpolated — the value only SELECTS between two
+    /// host-owned literals — so there is no injection surface at all here.
+    #[test]
+    fn steam_ui_is_a_closed_two_value_enum() {
+        assert!(valid_steam_ui("bigpicture"));
+        assert!(valid_steam_ui("desktop"));
+        assert!(!valid_steam_ui("gamepadui"));
+        assert!(!valid_steam_ui(""));
+        assert!(!valid_steam_ui("bigpicture; rm -rf ~"));
+    }
+
+    /// The `launcher_ui` kind exists because D4's original plan — non-Steam launchers riding the
+    /// `command` kind — stopped being available to plugins when the 2026-08-05 review made
+    /// `command` operator-only. A plugin names a launcher; the host builds the command.
+    #[test]
+    fn launcher_ui_accepts_only_launchers_this_host_can_open() {
+        #[cfg(target_os = "linux")]
+        {
+            assert!(valid_launcher_ui("heroic"));
+            assert!(valid_launcher_ui("lutris"));
+            // Not wired on this OS — refused inbound rather than becoming a tile that does nothing.
+            assert!(!valid_launcher_ui("gog"));
+        }
+        #[cfg(not(target_os = "linux"))]
+        {
+            // No Windows/macOS launcher UIs are wired yet, so every value is refused.
+            assert!(!valid_launcher_ui("heroic"));
+            assert!(!valid_launcher_ui("gog"));
+        }
+        assert!(!valid_launcher_ui(""));
+        assert!(!valid_launcher_ui("lutris; rm -rf ~"));
+    }
+
+    #[cfg(target_os = "linux")]
+    #[test]
+    fn launcher_ui_opens_the_launcher_itself() {
+        let ui = |v: &str| {
+            command_for(&LaunchSpec {
+                kind: "launcher_ui".into(),
+                value: v.into(),
+            })
+        };
+        // Bare `lutris` opens the window; the URI form is the `lutris_id` kind and launches a game.
+        assert_eq!(ui("lutris").as_deref(), Some("lutris"));
+        assert!(!ui("lutris").unwrap().contains("rungameid"));
+        // Heroic resolves the same way its game launches do, but with no `--no-gui` and no URI — so
+        // the window IS what opens. `None` on a box without Heroic, which is a correct answer.
+        if let Some(cmd) = ui("heroic") {
+            assert!(!cmd.contains("--no-gui"), "the GUI is the point: {cmd:?}");
+            assert!(!cmd.contains("heroic://"), "no game URI: {cmd:?}");
+        }
+        assert_eq!(ui("nonsense"), None);
+        assert_eq!(ui(""), None);
+    }
+
+    #[cfg(not(windows))]
+    #[test]
+    fn steam_ui_resolves_to_the_client_ui_on_linux() {
+        let ui = |v: &str| {
+            command_for(&LaunchSpec {
+                kind: "steam_ui".into(),
+                value: v.into(),
+            })
+        };
+        // Big Picture is the SteamOS game-mode shape; nested in gamescope this is what `--steam`
+        // integration is built around.
+        assert_eq!(ui("bigpicture").as_deref(), Some("steam -gamepadui"));
+        assert_eq!(ui("desktop").as_deref(), Some("steam"));
+        assert_eq!(ui("nonsense"), None);
+        assert_eq!(ui(""), None);
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn steam_ui_resolves_to_the_client_ui_on_windows() {
+        let ui = |v: &str| {
+            windows_launch_for(&LaunchSpec {
+                kind: "steam_ui".into(),
+                value: v.into(),
+            })
+        };
+        let (bp, wd) = ui("bigpicture").expect("bigpicture recipe");
+        assert!(bp.contains("steam://open/bigpicture"), "line was {bp:?}");
+        assert!(wd.is_none());
+        let (desk, _) = ui("desktop").expect("desktop recipe");
+        assert!(desk.contains("steam://open/main"), "line was {desk:?}");
+        assert!(ui("nonsense").is_none());
+        assert!(ui("").is_none());
+    }
+
+    #[test]
+    fn steam_appid_validation_accepts_appids_and_shortcut_gameids() {
+        assert!(valid_steam_appid("570"));
+        // The 64-bit shortcut game id shares the `steam_appid` kind — `rungameid` takes either.
+        assert!(valid_steam_appid(
+            &shortcut_gameid(2_456_789_012).to_string()
+        ));
+        assert!(!valid_steam_appid(""));
+        assert!(!valid_steam_appid("570; rm -rf ~"));
+        assert!(!valid_steam_appid("-1"));
+    }
+
+    /// Moved here with `shortcut_gameid` (WP1.1): the composed id is launch vocabulary, not
+    /// enumeration — the scanner only supplies the 32-bit appid it read out of `shortcuts.vdf`.
+    #[test]
+    fn shortcut_gameid_composes_appid_and_marker() {
+        let id = shortcut_gameid(0x8000_0000);
+        assert_eq!(id >> 32, 0x8000_0000, "high dword is the shortcut appid");
+        assert_eq!(id & 0xFFFF_FFFF, 0x0200_0000, "low dword is the marker");
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn epic_launch_uri_triple_bare_and_guard() {
+        assert_eq!(
+            epic_launch_uri("fn:abc:Fortnite").as_deref(),
+            Some("com.epicgames.launcher://apps/fn%3Aabc%3AFortnite?action=launch&silent=true")
+        );
+        assert_eq!(
+            epic_launch_uri("Fortnite").as_deref(),
+            Some("com.epicgames.launcher://apps/Fortnite?action=launch&silent=true")
+        );
+        assert!(epic_launch_uri("bad part:x:y").is_none()); // a space → rejected
+        assert!(epic_launch_uri("").is_none());
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn gog_spawn_parses_and_guards() {
+        let (cmd, wd) = gog_spawn("C:\\Games\\W3\\witcher3.exe\t--skip\tC:\\Games\\W3").unwrap();
+        assert_eq!(cmd, "\"C:\\Games\\W3\\witcher3.exe\" --skip");
+        assert_eq!(wd, Some(std::path::PathBuf::from("C:\\Games\\W3")));
+        let (cmd2, wd2) = gog_spawn("C:\\g.exe").unwrap();
+        assert_eq!(cmd2, "\"C:\\g.exe\"");
+        assert!(wd2.is_none());
+        assert!(gog_spawn("").is_none());
+    }
+
     #[cfg(windows)]
     #[test]
     fn windows_launch_for_maps_and_guards() {

crates/punktfunk-host/src/library/lutris.rs

@@ -84,6 +84,7 @@ fn lutris_games(db: &Path) -> rusqlite::Result<Vec<GameEntry>> {
     for (id, slug, name, directory) in rows.flatten() {
         games.push(GameEntry {
             provider: None,
+            role: GameRole::Game,
             meta: GameMeta::pc(),
             id: format!("lutris:{id}"),
             store: "lutris".into(),

crates/punktfunk-host/src/library/scanners.rs

@@ -12,19 +12,41 @@
 
 use super::*;
 
-/// One installed-store scanner this host build supports, with its enable state — the unit the
-/// console renders a toggle for. The list is platform-gated at compile time (the scanners are),
-/// so the console never shows a toggle that cannot do anything on this host.
+/// One **game source** on this host, with its enable state — the unit the console renders a toggle
+/// for. A source is either a scanner compiled into this build or a plugin that reconciles entries in
+/// (WP2.6); the console treats them identically, which is what makes the extraction invisible.
 #[derive(Clone, Debug, Serialize, ToSchema)]
 pub struct ScannerInfo {
-    /// Stable scanner id — the same string the scanner's entries carry in their `store` field.
+    /// Stable source id — the same string this source's entries carry in their `store` field. For a
+    /// plugin source it is also its provider id and its store claim: one string, by construction, so
+    /// a user's disabled state survives a built-in scanner being replaced by its plugin.
     #[schema(example = "steam")]
     pub id: String,
     /// Human-facing name for the console toggle.
     #[schema(example = "Steam")]
     pub label: String,
-    /// Whether this host runs the scanner (default true).
+    /// Whether this host runs the source (default true).
     pub enabled: bool,
+    /// Where the source comes from: `builtin` (a scanner in this host build) or `plugin`.
+    #[schema(example = "builtin")]
+    pub origin: SourceOrigin,
+    /// The provider id backing a `plugin` source — absent for a built-in scanner.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub provider: Option<String>,
+    /// How many entries this source currently contributes. `None` for a built-in scanner, whose
+    /// count would mean walking every launcher's files just to render a toggle.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub entries: Option<usize>,
+}
+
+/// Where a [`ScannerInfo`] comes from.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, ToSchema)]
+#[serde(rename_all = "lowercase")]
+pub enum SourceOrigin {
+    /// A scanner compiled into this host build.
+    Builtin,
+    /// A plugin reconciling entries over the provider API.
+    Plugin,
 }
 
 /// The scanners compiled into THIS host build: (id, label). Steam is cross-platform; the rest are
@@ -87,26 +109,93 @@ pub(crate) fn disabled_scanners() -> HashSet<String> {
     load_settings().disabled.into_iter().collect()
 }
 
-/// The scanners available on this platform with their current enable state, in the fixed
-/// definition order (stable for the console).
+/// Every game source on this host with its current enable state (WP2.6):
+///
+/// 1. the built-in scanners this build compiled in, **minus** any whose store a plugin has claimed
+///    (the plugin replaces it, so showing both would offer two toggles for one thing);
+/// 2. the claimed stores themselves, as plugin sources;
+/// 3. any other provider that has entries — the *emergent* case (rom-manager, playnite), which has
+///    never had a toggle before and gets one for free here.
+///
+/// Built-ins keep their fixed definition order (stable for the console); plugin sources follow,
+/// sorted by id.
 pub fn list_scanners() -> Vec<ScannerInfo> {
     let off = disabled_scanners();
-    scanner_defs()
+    let claims = crate::library::claimed_stores();
+    let entries = crate::library::load_custom();
+
+    let mut out: Vec<ScannerInfo> = scanner_defs()
         .into_iter()
+        .filter(|(id, _)| !claims.contains_key(*id))
         .map(|(id, label)| ScannerInfo {
             id: id.to_string(),
             label: label.to_string(),
             enabled: !off.contains(id),
+            origin: SourceOrigin::Builtin,
+            provider: None,
+            entries: None,
         })
-        .collect()
+        .collect();
+
+    // A claimed store shows under the SCANNER's label where we know one, so the row a user has been
+    // toggling for releases doesn't rename itself out from under them mid-migration.
+    let label_for = |id: &str| {
+        scanner_defs()
+            .into_iter()
+            .find(|(sid, _)| *sid == id)
+            .map(|(_, label)| label.to_string())
+            .unwrap_or_else(|| id.to_string())
+    };
+
+    let mut plugin_ids: Vec<(String, String)> = claims
+        .iter()
+        .map(|(store, provider)| (store.clone(), provider.clone()))
+        .collect();
+    // Emergent providers: any provider with entries that isn't already listed via a claim.
+    for e in &entries {
+        let Some(provider) = e.provider.as_deref() else {
+            continue;
+        };
+        if e.store.is_none() && !plugin_ids.iter().any(|(id, _)| id == provider) {
+            plugin_ids.push((provider.to_string(), provider.to_string()));
+        }
+    }
+    plugin_ids.sort();
+    plugin_ids.dedup();
+
+    out.extend(plugin_ids.into_iter().map(|(id, provider)| {
+        let count = entries
+            .iter()
+            .filter(|e| crate::library::source_id_for(e) == Some(id.as_str()))
+            .count();
+        ScannerInfo {
+            label: label_for(&id),
+            enabled: !off.contains(&id),
+            origin: SourceOrigin::Plugin,
+            provider: Some(provider),
+            entries: Some(count),
+            id,
+        }
+    }));
+    out
 }
 
-/// Enable/disable one scanner. `None` when `id` names no scanner available on this platform (the
-/// mgmt layer maps that to 404 — the console only ever sees this host's own list). Persists and
-/// emits `library.changed` (source = the scanner id) only when the state actually changed, so a
-/// repeated PUT is a cheap no-op.
+/// Whether `id` names a source that exists on this host right now — a compiled-in scanner, a claimed
+/// store, or a provider with entries. The toggle accepts exactly these (an unknown id still 404s).
+fn is_known_source(id: &str) -> bool {
+    scanner_defs().iter().any(|(sid, _)| *sid == id) || list_scanners().iter().any(|s| s.id == id)
+}
+
+/// Enable/disable one source. `None` when `id` names no source on this host (the mgmt layer maps
+/// that to 404 — the console only ever sees this host's own list). Persists and emits
+/// `library.changed` (source = the id) only when the state actually changed, so a repeated PUT is a
+/// cheap no-op.
+///
+/// The **same** `library-scanners.json` disabled-set backs built-in and plugin sources alike, and
+/// the ids match by construction — so a user who disabled `steam` before the migration still has it
+/// disabled after the steam plugin claims the store, with nothing to carry over.
 pub fn set_scanner_enabled(id: &str, enabled: bool) -> Result<Option<Vec<ScannerInfo>>> {
-    if !scanner_defs().iter().any(|(sid, _)| *sid == id) {
+    if !is_known_source(id) {
         return Ok(None);
     }
     let mut settings = load_settings();

crates/punktfunk-host/src/library/steam.rs

@@ -29,6 +29,7 @@ impl LibraryProvider for SteamProvider {
             .filter(|app| !is_steam_tool(app.appid, &app.name))
             .map(|app| GameEntry {
                 provider: None,
+                role: GameRole::Game,
                 meta: GameMeta::pc(),
                 id: format!("steam:{}", app.appid),
                 store: "steam".into(),
@@ -383,6 +384,7 @@ fn shortcut_entry(sc: Shortcut) -> Option<GameEntry> {
     }
     Some(GameEntry {
         provider: None,
+        role: GameRole::Game,
         meta: GameMeta::pc(),
         id: format!("steam:{}", sc.appid),
         store: "steam".into(),
@@ -426,12 +428,8 @@ fn shortcuts_files() -> Vec<PathBuf> {
     files
 }
 
-/// The 64-bit game id `steam://rungameid/` needs to launch a non-Steam shortcut: high dword = the
-/// 32-bit shortcut appid, low dword = the shortcut marker `0x0200_0000`. (Handing `rungameid` the
-/// bare 32-bit appid does not launch a shortcut — it must be this composed id.)
-fn shortcut_gameid(appid: u32) -> u64 {
-    ((appid as u64) << 32) | 0x0200_0000
-}
+// `shortcut_gameid` (the 64-bit `rungameid` composition) moved to `launch.rs` (WP1.1) — it is launch
+// vocabulary; this module only reads the 32-bit appid out of `shortcuts.vdf`.
 
 /// The 32-bit appid Steam derives for a shortcut from its target+name — `crc32(exe + name)` with the
 /// high bit set. Only used when `shortcuts.vdf` omits the stored `appid` (very old Steam); modern
@@ -762,12 +760,7 @@ mod tests {
         assert!(launch.value.bytes().all(|b| b.is_ascii_digit()));
     }
 
-    #[test]
-    fn shortcut_gameid_composes_appid_and_marker() {
-        let id = shortcut_gameid(0x8000_0000);
-        assert_eq!(id >> 32, 0x8000_0000); // high dword is the appid
-        assert_eq!(id & 0xFFFF_FFFF, 0x0200_0000); // low dword is the shortcut marker
-    }
+    // `shortcut_gameid_composes_appid_and_marker` moved with the function to `launch.rs` (WP1.1).
 
     #[test]
     fn crc32_matches_the_known_check_value_and_derives_a_high_bit_appid() {

crates/punktfunk-host/src/library/xbox.rs

@@ -70,6 +70,7 @@ fn xbox_games() -> Vec<GameEntry> {
             let art = cached_art(&id).unwrap_or_default();
             games.push(GameEntry {
                 provider: None,
+                role: GameRole::Game,
                 meta: GameMeta::pc(),
                 id,
                 store: "xbox".into(),

crates/punktfunk-host/src/mgmt/library.rs

@@ -31,7 +31,8 @@ fn check_entry_fields(
                 &format!(
                     "`{field}` is executed as the host user and may only be set with the \
                      operator's admin token — a plugin may publish entries with any host-resolved \
-                     launch kind (steam_appid, epic, gog, aumid, lutris_id, heroic) instead"
+                     launch kind (steam_appid, steam_ui, launcher_ui, epic, gog, aumid, lutris_id, heroic) \
+                     instead"
                 ),
             ));
         }
@@ -249,6 +250,11 @@ pub(crate) async fn update_custom_game(
             StatusCode::CONFLICT,
             &format!("entry is owned by provider `{p}` — update it through its reconcile"),
         ),
+        // Store claims are a reconcile-only concern — the manual CRUD never requests one.
+        Ok(MutateOutcome::StoreClaimed { .. }) => api_error(
+            StatusCode::INTERNAL_SERVER_ERROR,
+            "unexpected claim outcome",
+        ),
         Err(e) => api_error(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
     }
 }
@@ -280,6 +286,11 @@ pub(crate) async fn delete_custom_game(Path(id): Path<String>) -> Response {
                 "entry is owned by provider `{p}` — remove it there, or DELETE the provider set"
             ),
         ),
+        // Store claims are a reconcile-only concern — the manual CRUD never requests one.
+        Ok(MutateOutcome::StoreClaimed { .. }) => api_error(
+            StatusCode::INTERNAL_SERVER_ERROR,
+            "unexpected claim outcome",
+        ),
         Err(e) => api_error(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
     }
 }
@@ -291,6 +302,13 @@ pub(crate) struct ProviderRemoved {
     removed: usize,
 }
 
+/// Query for `reconcileProviderEntries` — the optional store claim (D2).
+#[derive(Deserialize)]
+pub(crate) struct ReconcileQuery {
+    /// Claim this store for the provider, so its entries take the store's own identity.
+    store: Option<String>,
+}
+
 /// Replace a provider's library entries (declarative reconcile)
 ///
 /// Atomically replaces the full entry set owned by `{provider}` (RFC §8): the payload is the
@@ -298,28 +316,47 @@ pub(crate) struct ProviderRemoved {
 /// surviving title's host id stable across reconciles, drops orphans, and never touches manual
 /// entries or other providers'. An empty array removes everything the provider owns. Emits
 /// `library.changed` with the provider as `source`.
+///
+/// `?store=` additionally **claims** that store for the provider: its entries then surface with
+/// deterministic `<store>:<external_id>` ids and the store's own badge, instead of opaque
+/// `custom:<id>` ones — which is what lets a library plugin reproduce the entries an in-host scanner
+/// used to produce, right down to the GameStream app ids and client-side art caches. One provider
+/// per store; a second claimant gets 409. While a claim is held the matching built-in scanner is
+/// suppressed, so the two never double-list. The claim is released by `DELETE`, not by an empty
+/// reconcile (a store can legitimately have zero installed titles).
 #[utoipa::path(
     put,
     path = "/library/provider/{provider}",
     tag = "library",
     operation_id = "reconcileProviderEntries",
-    params(("provider" = String, Path, description = "The provider id ([a-z0-9._-], `manual` reserved)")),
+    params(
+        ("provider" = String, Path, description = "The provider id ([a-z0-9._-], `manual` reserved)"),
+        ("store" = Option<String>, Query, description = "Claim this store for the provider ([a-z0-9_-], `custom`/`manual` reserved)"),
+    ),
     request_body = Vec<crate::library::ProviderEntryInput>,
     responses(
         (status = OK, description = "The provider's resulting entries (host ids assigned/kept)", body = [crate::library::CustomEntry]),
-        (status = BAD_REQUEST, description = "Invalid provider id or payload", body = ApiError),
+        (status = BAD_REQUEST, description = "Invalid provider id, store id, or payload", body = ApiError),
         (status = UNAUTHORIZED, description = "Missing or invalid bearer token", body = ApiError),
+        (status = CONFLICT, description = "That store is already claimed by another provider", body = ApiError),
         (status = INTERNAL_SERVER_ERROR, description = "Could not persist the catalog", body = ApiError),
     )
 )]
 pub(crate) async fn reconcile_provider_entries(
     Extension(lane): Extension<AuthLane>,
     Path(provider): Path<String>,
+    Query(q): Query<ReconcileQuery>,
     ApiJson(inputs): ApiJson<Vec<crate::library::ProviderEntryInput>>,
 ) -> Response {
     if let Err(e) = crate::library::validate_provider_name(&provider) {
         return api_error(StatusCode::BAD_REQUEST, &e);
     }
+    let store = q.store.filter(|s| !s.is_empty());
+    if let Some(store) = &store {
+        if let Err(e) = crate::library::validate_store_claim(store) {
+            return api_error(StatusCode::BAD_REQUEST, &e);
+        }
+    }
     if let Err(e) = crate::library::validate_provider_payload(&inputs) {
         return api_error(StatusCode::BAD_REQUEST, &e);
     }
@@ -335,15 +372,24 @@ pub(crate) async fn reconcile_provider_entries(
             return denied;
         }
     }
-    match crate::library::reconcile_provider(&provider, inputs) {
-        Ok(entries) => {
+    match crate::library::reconcile_provider(&provider, store.as_deref(), inputs) {
+        Ok(crate::library::MutateOutcome::Done(entries)) => {
             tracing::info!(
                 provider,
+                store = store.as_deref().unwrap_or("-"),
                 count = entries.len(),
                 "library provider reconciled"
             );
             Json(entries).into_response()
         }
+        Ok(crate::library::MutateOutcome::StoreClaimed { store, provider }) => api_error(
+            StatusCode::CONFLICT,
+            &format!("store `{store}` is already claimed by provider `{provider}`"),
+        ),
+        Ok(_) => api_error(
+            StatusCode::INTERNAL_SERVER_ERROR,
+            "unexpected reconcile outcome",
+        ),
         Err(e) => api_error(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
     }
 }
@@ -383,11 +429,12 @@ pub(crate) async fn delete_provider_entries(Path(provider): Path<String>) -> Res
 /// Fetch one cover-art image for a library entry
 ///
 /// Resolves `kind` (`portrait` | `hero` | `logo` | `header`) for the given library id and streams
-/// the image bytes. For a Steam title, the host's own local Steam cache is tried first (exact —
-/// it's what the user's Steam client already shows for it), the public Steam CDN's flat URL
-/// convention as a fallback (newer titles' CDN assets can live at a per-asset-hash path the host
-/// can't predict, in which case this 404s and the client falls through to its next art candidate).
-/// Only Steam ids are backed today; any other store 404s.
+/// the image bytes. Any id stored in the host's catalog (manual entries, provider-synced entries,
+/// and a library plugin's claimed-store entries) serves its local art file. A Steam title falls back
+/// to the in-host scanner's resolver: the host's own local Steam cache first (exact — it's what the
+/// user's Steam client already shows for it), the public Steam CDN's flat URL convention second
+/// (newer titles' CDN assets can live at a per-asset-hash path the host can't predict, in which case
+/// this 404s and the client falls through to its next art candidate).
 #[utoipa::path(
     get,
     path = "/library/art/{id}/{kind}",
@@ -407,7 +454,20 @@ pub(crate) async fn get_library_art(Path((id, kind)): Path<(String, String)>) ->
     let Some(kind) = crate::library::ArtKind::parse(&kind) else {
         return api_error(StatusCode::NOT_FOUND, "unknown art kind");
     };
-    // Steam: CDN / local-cache proxy (id `steam:<appid>`).
+    // `library.json` FIRST, for ANY id (WP1.2). Stored entries — manual, provider-synced, and (once
+    // store claims land) a scanner plugin's `steam:570` — all serve their local art file from here,
+    // so the proxy never has to know which store an id belongs to. Steam ids aren't stored today, so
+    // this misses and the legacy branch below still answers them.
+    let stored = {
+        let id = id.clone();
+        tokio::task::spawn_blocking(move || crate::library::library_local_art_bytes(&id, kind))
+            .await
+    };
+    if let Ok(Some((bytes, ctype))) = stored {
+        return ([(header::CONTENT_TYPE, ctype)], bytes).into_response();
+    }
+    // Legacy in-host Steam scanner: local Steam cache, then the flat CDN URL. Retired with the
+    // scanner itself once the steam plugin claims the store (M6).
     if let Some(appid) = id
         .strip_prefix("steam:")
         .and_then(|s| s.parse::<u32>().ok())
@@ -421,17 +481,5 @@ pub(crate) async fn get_library_art(Path((id, kind)): Path<(String, String)>) ->
             _ => api_error(StatusCode::NOT_FOUND, "no art of that kind for this title"),
         };
     }
-    // Custom/provider entry (id `custom:<id>`): serve its stored LOCAL art file — e.g. the Playnite
-    // plugin's covers, reconciled as on-host paths rather than inlined bytes.
-    if let Some(cid) = id.strip_prefix("custom:").map(str::to_owned) {
-        return match tokio::task::spawn_blocking(move || {
-            crate::library::custom_local_art_bytes(&cid, kind)
-        })
-        .await
-        {
-            Ok(Some((bytes, ctype))) => ([(header::CONTENT_TYPE, ctype)], bytes).into_response(),
-            _ => api_error(StatusCode::NOT_FOUND, "no art of that kind for this title"),
-        };
-    }
-    api_error(StatusCode::NOT_FOUND, "no art proxy for this store")
+    api_error(StatusCode::NOT_FOUND, "no art of that kind for this title")
 }

crates/punktfunk-host/src/mgmt/plugins.rs

@@ -64,6 +64,14 @@ pub(crate) struct PluginRegistration {
     /// entry only (e.g. a future runner-management listing) and grows no nav entry.
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub ui: Option<PluginUi>,
+    /// What KIND of plugin this is (`^[a-z][a-z0-9-]{0,31}$`), top-level rather than under `ui`
+    /// because it describes the plugin, not its surface. The console knows one value today —
+    /// `library` — which it filters **out of the nav**: six installed scanner plugins would otherwise
+    /// flood the sidebar, and their real entry point is the Game sources surface (design D5). A
+    /// library plugin that genuinely wants its own page (rom-manager, which is much more than a
+    /// scanner) simply omits the category.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub category: Option<String>,
 }
 
 /// One log line produced by the runner or a plugin inside it (`POST /plugins/logs`).
@@ -104,6 +112,9 @@ pub(crate) struct PluginSummary {
     pub version: Option<String>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub ui: Option<PluginUiPublic>,
+    /// The plugin's kind — see [`PluginRegistration::category`].
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub category: Option<String>,
 }
 
 /// `GET /plugins/{id}/ui-credential` — the console proxy's server-side lookup (bearer + loopback).
@@ -129,14 +140,19 @@ struct Stored {
     title: String,
     version: Option<String>,
     ui: Option<StoredUi>,
+    category: Option<String>,
     expires_at: Instant,
 }
 
 impl Stored {
     /// Do the operator-visible fields match (ignoring the lease clock)? A pure lease renewal leaves
-    /// these unchanged and emits no event; a restart (new secret) or a re-scan (new title/icon) does.
-    fn public_eq(&self, title: &str, version: &Option<String>, ui: &Option<StoredUi>) -> bool {
-        self.title == title && self.version == *version && self.ui == *ui
+    /// these unchanged and emits no event; a restart (new secret) or a re-scan (new title/icon/
+    /// category) does.
+    fn public_eq(&self, v: &Valid) -> bool {
+        self.title == v.title
+            && self.version == v.version
+            && self.ui == v.ui
+            && self.category == v.category
     }
 }
 
@@ -150,6 +166,7 @@ struct Valid {
     title: String,
     version: Option<String>,
     ui: Option<StoredUi>,
+    category: Option<String>,
 }
 
 impl PluginRegistry {
@@ -167,7 +184,7 @@ impl PluginRegistry {
         let mut map = self.inner.write().unwrap_or_else(|e| e.into_inner());
         let changed = match map.get(id) {
             // An *expired* prior entry counts as a change (it had stopped listing).
-            Some(prev) => !prev.is_live() || !prev.public_eq(&v.title, &v.version, &v.ui),
+            Some(prev) => !prev.is_live() || !prev.public_eq(&v),
             None => true,
         };
         map.insert(
@@ -176,6 +193,7 @@ impl PluginRegistry {
                 title: v.title,
                 version: v.version,
                 ui: v.ui,
+                category: v.category,
                 expires_at,
             },
         );
@@ -207,6 +225,7 @@ impl PluginRegistry {
                     port: u.port,
                     icon: u.icon.clone(),
                 }),
+                category: s.category.clone(),
             })
             .collect();
         live.sort_by(|a, b| a.title.cmp(&b.title).then_with(|| a.id.cmp(&b.id)));
@@ -333,7 +352,31 @@ fn validate(reg: PluginRegistration) -> Result<Valid, String> {
         Some(u) => Some(validate_ui(u)?),
         None => None,
     };
-    Ok(Valid { title, version, ui })
+    // Categories are grouping keys the console switches on — a closed charset, but deliberately not
+    // a closed VOCABULARY: an unknown category is stored and simply matches no console rule, so a
+    // newer plugin registering against an older host degrades to "shows in the nav", never to a
+    // failed registration.
+    let category = match reg.category {
+        Some(c) => {
+            let ok = (1..=32).contains(&c.len())
+                && c.starts_with(|ch: char| ch.is_ascii_lowercase())
+                && c.bytes()
+                    .all(|b| b.is_ascii_lowercase() || b.is_ascii_digit() || b == b'-');
+            if !ok {
+                return Err(
+                    "category must be 1–32 chars of [a-z0-9-], starting with a letter".into(),
+                );
+            }
+            Some(c)
+        }
+        None => None,
+    };
+    Ok(Valid {
+        title,
+        version,
+        ui,
+        category,
+    })
 }
 
 fn validate_ui(u: PluginUi) -> Result<StoredUi, String> {
@@ -558,6 +601,7 @@ mod tests {
                 secret: secret.into(),
                 icon: Some("gamepad-2".into()),
             }),
+            category: None,
         }
     }
 
@@ -584,10 +628,30 @@ mod tests {
             title: "Ro\u{7}m\n".into(),
             version: None,
             ui: None,
+            category: None,
         })
         .unwrap();
         assert_eq!(v.title, "Rom");
-        // privileged port rejected
+        // Category charset (WP2.7): the console's one known value passes; the shapes that would
+        // break a grouping key don't. An UNKNOWN-but-well-formed category is accepted on purpose —
+        // a newer plugin must not fail to register against an older host.
+        let lib = |c: &str| PluginRegistration {
+            title: "X".into(),
+            version: None,
+            ui: None,
+            category: Some(c.into()),
+        };
+        assert_eq!(
+            validate(lib("library")).unwrap().category.as_deref(),
+            Some("library")
+        );
+        assert!(validate(lib("some-future-kind")).is_ok());
+        assert!(validate(lib("")).is_err());
+        assert!(validate(lib("Library")).is_err()); // no uppercase
+        assert!(validate(lib("9lives")).is_err()); // must start with a letter
+        assert!(validate(lib("lib_rary")).is_err()); // no underscore
+        assert!(validate(lib(&"a".repeat(33))).is_err()); // too long
+                                                          // privileged port rejected
         assert!(validate(reg("x", 80, SECRET)).is_err());
         // short secret rejected
         assert!(validate(reg("x", 49321, "tooshort")).is_err());
@@ -641,6 +705,7 @@ mod tests {
                 title: "Headless".into(),
                 version: None,
                 ui: None,
+                category: None,
             })
             .unwrap(),
         );

crates/punktfunk-host/src/mgmt/store.rs

@@ -108,6 +108,14 @@ pub(crate) struct CatalogEntry {
     /// A revocation covering the catalogued version — do not offer this without shouting.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub blocked: Option<String>,
+    /// What kind of plugin this is — the console filters Browse by these, and the Game sources
+    /// surface's "Add a source" rail shows exactly the `library` ones (design D5/D6).
+    pub categories: Vec<String>,
+    /// Whether the launcher this plugin scans looks **installed on this host** (design D8), from the
+    /// index's own existence probes. `null` = the entry declares no probes for this platform, which
+    /// the console renders as "unknown" rather than "not installed".
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub detected: Option<bool>,
 }
 
 #[derive(Serialize, ToSchema)]
@@ -277,6 +285,8 @@ fn build_catalog(force: bool) -> CatalogResponse {
                 update_available: installed_version.as_deref().is_some_and(|v| v != e.version),
                 installed_version,
                 blocked: store::advisory_for(&e.pkg, Some(&e.version)).map(|a| a.reason),
+                categories: e.categories.clone(),
+                detected: e.detected(),
             });
         }
     }

crates/punktfunk-host/src/store/index.rs

@@ -97,6 +97,31 @@ pub(crate) struct Entry {
     /// Host platforms this plugin works on (`linux`/`windows`/`macos`). Empty ⇒ all.
     #[serde(default)]
     pub platforms: Vec<String>,
+    /// What kinds of plugin this is (`[a-z][a-z0-9-]{0,31}`, ≤4). The console filters Browse by
+    /// these, and the Game sources surface's "Add a source" rail lists exactly the entries carrying
+    /// `library` (design D5/D6). Additive: an older host ignores the field, a newer one just sees no
+    /// categories on an older index.
+    #[serde(default)]
+    pub categories: Vec<String>,
+    /// Optional per-platform "is this launcher installed here?" probes (design D8).
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub detect: Option<DetectProbes>,
+}
+
+/// Existence probes that let the console badge a catalog row "detected on this host" **without the
+/// host re-growing per-store knowledge** — the whole point of extracting the scanners. Store
+/// knowledge lives in the updatable, signed index; the host stays generic and only evaluates.
+///
+/// Deliberately anaemic: a probe is a path or an `HKLM\…` registry key, checked for EXISTENCE only.
+/// No reads, no content matching, no globbing beyond a single `*` segment. The index is
+/// operator-trusted but remotely updatable, so a probe must never be able to exfiltrate anything or
+/// cost more than a stat.
+#[derive(Debug, Clone, Default, Deserialize, Serialize)]
+pub(crate) struct DetectProbes {
+    #[serde(default)]
+    pub linux: Vec<String>,
+    #[serde(default)]
+    pub windows: Vec<String>,
 }
 
 #[derive(Debug, Clone, Deserialize, Serialize)]
@@ -228,9 +253,40 @@ impl Entry {
         self.platforms
             .retain(|p| matches!(p.as_str(), "linux" | "windows" | "macos"));
         self.platforms.truncate(4);
+        // Categories and probes are cosmetic/advisory: a malformed one is dropped, never fatal to
+        // the entry — a plugin must stay installable even if a future index writes a category this
+        // host build has never heard of.
+        self.categories.retain(|c| valid_category(c));
+        self.categories.truncate(4);
+        if let Some(d) = &mut self.detect {
+            d.linux.retain(|p| valid_probe(p));
+            d.windows.retain(|p| valid_probe(p));
+            d.linux.truncate(MAX_PROBES);
+            d.windows.truncate(MAX_PROBES);
+            if d.linux.is_empty() && d.windows.is_empty() {
+                self.detect = None;
+            }
+        }
         Ok(())
     }
 
+    /// Does this entry's platform probe match on the running host? `None` = the entry declares no
+    /// probes for this platform, i.e. "unknown", which the console renders differently from "no".
+    pub(crate) fn detected(&self) -> Option<bool> {
+        let probes = self.detect.as_ref()?;
+        let list = if cfg!(windows) {
+            &probes.windows
+        } else if cfg!(target_os = "linux") {
+            &probes.linux
+        } else {
+            return None;
+        };
+        if list.is_empty() {
+            return None;
+        }
+        Some(list.iter().any(|p| probe_matches(p)))
+    }
+
     /// Is this entry installable on the running host? Returns the operator-facing reason when not.
     pub(crate) fn incompatible_reason(&self) -> Option<String> {
         if !self.platforms.is_empty() && !self.platforms.iter().any(|p| p == HOST_PLATFORM) {
@@ -372,6 +428,94 @@ fn is_https(url: &str) -> bool {
     url.starts_with("https://") && url.len() > "https://".len()
 }
 
+/// A plugin category (design D5): same shape the registration API accepts, so a plugin's declared
+/// category and its catalog row can never disagree about spelling.
+fn valid_category(c: &str) -> bool {
+    (1..=32).contains(&c.len())
+        && c.starts_with(|ch: char| ch.is_ascii_lowercase())
+        && c.bytes()
+            .all(|b| b.is_ascii_lowercase() || b.is_ascii_digit() || b == b'-')
+}
+
+/// How many probes one platform may declare — a handful of well-chosen paths covers any launcher,
+/// and the cap bounds the stat cost of rendering the catalog.
+const MAX_PROBES: usize = 8;
+
+/// Is this a probe the host will evaluate? An **absolute** filesystem path with at most one `*`
+/// segment, or an `HKLM\…` registry key. Everything else is dropped.
+///
+/// The restrictions are the security model (D8). Absolute: a relative path would resolve against
+/// whatever the host's cwd happens to be. One `*` segment: bounded fan-out, so a probe can't walk a
+/// tree. `HKLM` only: `HKCU` is unreadable as LocalService anyway, and pointing the host at an
+/// arbitrary hive is not something a remote index should be able to ask for.
+fn valid_probe(p: &str) -> bool {
+    if p.is_empty() || p.len() > 260 {
+        return false;
+    }
+    if let Some(key) = p.strip_prefix("HKLM\\") {
+        return !key.is_empty()
+            && !key.contains("..")
+            && key.bytes().all(|b| {
+                b.is_ascii_alphanumeric() || matches!(b, b'\\' | b' ' | b'-' | b'_' | b'.')
+            });
+    }
+    let b = p.as_bytes();
+    let absolute = p.starts_with('/') || (b.len() >= 3 && b[1] == b':' && b[2] == b'\\');
+    // No traversal, and at most ONE wildcard segment (`~` is not expanded — the host runs as a
+    // service account whose home means nothing to a user's launcher install).
+    absolute && !p.contains("..") && p.matches('*').count() <= 1
+}
+
+/// Evaluate one probe: does the path (or registry key) exist? Existence only — never a read.
+fn probe_matches(p: &str) -> bool {
+    #[cfg(windows)]
+    if let Some(key) = p.strip_prefix("HKLM\\") {
+        use std::os::windows::process::CommandExt;
+        // `reg.exe query` rather than a registry crate: dependency-free, and it is exactly what a
+        // library plugin will use for the same job under LocalService.
+        const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+        return std::process::Command::new("reg.exe")
+            .args(["query", &format!("HKLM\\{key}")])
+            .creation_flags(CREATE_NO_WINDOW)
+            .stdout(std::process::Stdio::null())
+            .stderr(std::process::Stdio::null())
+            .status()
+            .map(|s| s.success())
+            .unwrap_or(false);
+    }
+    #[cfg(not(windows))]
+    if p.starts_with("HKLM\\") {
+        return false; // a Windows probe on a POSIX host is simply not a match
+    }
+    match p.split_once('*') {
+        None => std::path::Path::new(p).exists(),
+        // One wildcard: list the parent of the wildcard segment and match the fixed prefix/suffix
+        // around it. Bounded to a single directory read.
+        Some((before, after)) => {
+            let (dir, prefix) = match before.rfind(['/', '\\']) {
+                Some(i) => (&before[..=i], &before[i + 1..]),
+                None => return false, // a wildcard with no directory to anchor it
+            };
+            let (suffix, rest) = match after.find(['/', '\\']) {
+                Some(i) => (&after[..i], &after[i..]),
+                None => (after, ""),
+            };
+            let Ok(read) = std::fs::read_dir(dir) else {
+                return false;
+            };
+            read.flatten().any(|e| {
+                let name = e.file_name();
+                let name = name.to_string_lossy();
+                name.starts_with(prefix)
+                    && name.ends_with(suffix)
+                    && name.len() >= prefix.len() + suffix.len()
+                    && (rest.is_empty()
+                        || e.path().join(rest.trim_start_matches(['/', '\\'])).exists())
+            })
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -401,6 +545,73 @@ mod tests {
         assert!(Index::parse(b"not json").is_err());
     }
 
+    /// WP2.8 is additive on purpose — SCHEMA stays 1. An index written by a newer curator must load
+    /// on an older host (unknown fields ignored) and vice versa (absent fields default), or the
+    /// signed-index rollout would need a flag day.
+    #[test]
+    fn categories_and_probes_are_additive_and_sanitized() {
+        // An entry with NEITHER field — every index in the wild today.
+        let e = &Index::parse(&doc(GOOD)).unwrap().plugins[0];
+        assert!(e.categories.is_empty());
+        assert!(e.detect.is_none());
+        assert_eq!(e.detected(), None, "no probes ⇒ unknown, not `false`");
+
+        // With both, including rows that must be dropped rather than fail the entry.
+        let rich = GOOD.trim_end_matches('}').to_string()
+            + r#","categories":["library","Bad Cat","x","y","z","w"],
+                 "detect":{"linux":["/usr/bin/steam","relative/path","/etc/../etc/passwd"],
+                           "windows":["HKLM\\SOFTWARE\\Valve\\Steam","HKCU\\SOFTWARE\\Valve"]}}"#;
+        let e = &Index::parse(&doc(&rich)).unwrap().plugins[0];
+        assert_eq!(
+            e.categories,
+            ["library", "x", "y", "z"],
+            "malformed dropped, capped at 4"
+        );
+        let d = e.detect.as_ref().expect("probes kept");
+        assert_eq!(d.linux, ["/usr/bin/steam"], "relative + traversal dropped");
+        assert_eq!(
+            d.windows,
+            ["HKLM\\SOFTWARE\\Valve\\Steam"],
+            "HKCU is not evaluable as LocalService — dropped"
+        );
+    }
+
+    #[test]
+    fn probe_shapes_are_bounded() {
+        assert!(valid_probe("/usr/bin/steam"));
+        assert!(
+            valid_probe("/home/*/.steam"),
+            "one wildcard segment is fine"
+        );
+        assert!(valid_probe(r"C:\Program Files (x86)\Steam\steam.exe"));
+        assert!(valid_probe(r"HKLM\SOFTWARE\WOW6432Node\Valve\Steam"));
+        // Rejected: relative, traversal, more than one wildcard, other hives, absurd length.
+        assert!(!valid_probe("steam"));
+        assert!(!valid_probe("/usr/../etc/passwd"));
+        assert!(!valid_probe("/home/*/games/*/steam"));
+        assert!(!valid_probe(r"HKCU\SOFTWARE\Valve"));
+        assert!(!valid_probe(""));
+        assert!(!valid_probe(&"/x".repeat(200)));
+    }
+
+    /// The evaluator does existence checks only, against real paths, and never reads a byte.
+    #[test]
+    fn probes_evaluate_against_the_filesystem() {
+        let dir = std::env::temp_dir().join(format!("pf-probe-{}", std::process::id()));
+        let nested = dir.join("SteamLibrary-42");
+        std::fs::create_dir_all(nested.join("steamapps")).unwrap();
+        let d = dir.to_string_lossy().into_owned();
+
+        assert!(probe_matches(&format!("{d}/SteamLibrary-42")));
+        assert!(!probe_matches(&format!("{d}/nope")));
+        // One wildcard segment, with and without a trailing fixed component.
+        assert!(probe_matches(&format!("{d}/SteamLibrary-*")));
+        assert!(probe_matches(&format!("{d}/SteamLibrary-*/steamapps")));
+        assert!(!probe_matches(&format!("{d}/SteamLibrary-*/nope")));
+        assert!(!probe_matches(&format!("{d}/Other-*")));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
     #[test]
     fn drops_invalid_entries_but_keeps_the_rest() {
         let bad_unscoped = GOOD.replace("@punktfunk/plugin-rom-manager", "punktfunk-plugin-x");

docs-site/content/docs/plugins.mdx

@@ -108,10 +108,16 @@ the full path: `& "$env:ProgramFiles\punktfunk\punktfunk-host.exe" plugins add p
 Open the [web console](/docs/web-console) and the plugin's page appears in the nav automatically —
 that's the whole install.
 
-The runner is **opt-in**: `plugins add` installs, `plugins enable` turns it on. You only need
-`enable` once. The runner discovers plugins when it starts, so one installed later needs a restart
-to come up (`systemctl --user restart punktfunk-scripting`, or `Restart` the `PunktfunkScripting`
-task) — the console does that restart for you as part of installing.
+The runner is **on by default** on a new install — your game sources are plugins, so a host without
+it would show an empty library. (On a host that predates this, it stays however you left it; turn it
+on with `punktfunk-host plugins enable`, which you only need once.) The runner discovers plugins
+when it starts, so one installed later needs a restart to come up
+(`systemctl --user restart punktfunk-scripting`, or `Restart` the `PunktfunkScripting` task) — the
+console does that restart for you as part of installing.
+
+Don't want it? It is a normal service you can switch off: `systemctl --user mask punktfunk-scripting`
+on Linux, or disable the `PunktfunkScripting` scheduled task on Windows. Your host keeps streaming;
+you just lose plugin-provided game sources and any automation.
 
 A plugin installed from the CLI shows up in the console as **Installed via CLI**: the console knows
 what is installed, but not who vouched for it. Install the same plugin from the store's Browse tab
@@ -301,8 +307,8 @@ host's, on one timeline, with the same search and download. Each is tagged `plug
 plugin's own name for lines it logged itself, `plugin:runner` for the supervisor's (starting a
 plugin, restarting a crashed one, refusing an unsafe file).
 
-An empty Plugins view almost always means the runner isn't running — it is a separate service, and
-opt-in on Linux. Check with `punktfunk-host plugins status`.
+An empty Plugins view almost always means the runner isn't running — it is a separate service. Check
+with `punktfunk-host plugins status`.
 
 <Callout>
 Nothing is lost if the host is down: the runner keeps buffering and sends the backlog when the host

docs-site/content/docs/stats.md

@@ -7,13 +7,20 @@ Every Punktfunk client has an in-stream stats overlay. All clients use **the sam
 vocabulary and the same four measurement points**, so a stage name on your phone means
 what the same name means on your desktop.
 
-Two platforms differ in the *math*: on **iOS and tvOS** the headline is **floor-shaved**.
-The fixed depth of Apple's present pipeline — roughly two refresh intervals, which no
-client can pace under — is excluded from it, and the Detailed tier prints the excluded
+Some platforms differ in the *math*: on **iOS, tvOS and Android** the headline is
+**floor-shaved**. The depth of the OS present pipeline — the compositor's own wait, which
+no client can pace under — is excluded from it, and the Detailed tier prints the excluded
 term on its own line as `os present +X.X excluded (display pipeline minimum)`. Add that
-floor back before holding an iPhone, iPad or Apple TV's `capture→on-glass` next to a
-macOS, Linux, Windows or Android one. (The macOS client shaves nothing: it presents
-straight to the display, with no such pipeline depth to measure, so its numbers are raw.)
+floor back before holding an iPhone, iPad, Apple TV or Android device's headline next to a
+macOS, Linux or Windows one. (The macOS client shaves nothing: it presents straight to the
+display, with no such pipeline depth to measure, so its numbers are raw.)
+
+The floor is **measured, not assumed**, and it is not small: it is commonly one to two
+refresh intervals, which on a 60 Hz phone is more than 30 ms — enough on its own to dwarf
+everything Moonlight's overlay displays. Charging it to the stream made Punktfunk look
+slower than clients that simply never measure that far (see
+[Comparing with Moonlight / Sunshine](#comparing-with-moonlight--sunshine)), so we report
+it rather than bury it in the total.
 
 ## The four measurement points
 
@@ -47,7 +54,7 @@ captured input, switch mouse mode, disconnect, mute the microphone — are in
 lost). **Normal** adds the stream line and the p50/p95 headline. **Detailed** adds the per-stage
 breakdown everywhere; on Linux/Windows it also adds the encoder's target bitrate, the decode path,
 an HDR tag and a chroma tag, on Android the decoder plus the full codec/bit-depth/colour line, and
-on iOS/tvOS the excluded OS present floor.
+on iOS, tvOS and Android the excluded OS present floor.
 You can also set the level a stream starts at in each client's
 [Settings](/docs/client-settings#overlay). The examples below are the **Detailed** view.
 
@@ -68,14 +75,16 @@ present: mailbox
 lost 3 (2.4%)
 ```
 
-Android:
+Android (headline and `display` both floor-shaved, like the Apple clients — the raw
+end-to-end here is 30.9 ms, the 16.7 ms floor of a 120 Hz panel included):
 
 ```
 1920×1080@120   120 fps   24.3 Mb/s
 c2.qti.hevc.decoder · low-latency
 HEVC · 10-bit · HDR (BT.2020 PQ) · 4:2:0
 end-to-end 14.2 ms p50 · 19.8 p95 · capture→displayed
-= host 3.1 + network 6.7 + decode 2.1 + display 2.3
+= host 3.1 + network 6.7 + decode 2.1 + display 2.3   · presents 119
+os present +16.7 excluded (display pipeline minimum)
 lost 3 (2.4%) · skipped 1 · FEC 12
 ```
 
@@ -131,18 +140,22 @@ lost 3 (2.4%)
     the screen's refresh cycle, not the stream; a large `pace` is us. (`pace` is also the
     fair number to compare against an iPhone or iPad, whose figure already has its
     equivalent of `latch` removed.)
-  - `os present` *(iOS and tvOS)* — the fixed depth of the OS present pipeline, which is
+  - `os present` *(iOS, tvOS and Android)* — the depth of the OS present pipeline, which is
     excluded from both the headline and `display` and printed here so you can add it
-    back.
+    back. On Android it is the measured time SurfaceFlinger took to latch and scan out each
+    frame, so it moves with your panel's rate and with whatever low-latency mode the vendor
+    applied; on Apple it is measured from the display link's own lead.
   - `client queue` *(Apple only)* — how long a received frame waited before the decoder
     pulled it. It's the front part of `decode`, not time on top of it. Hidden below 2 ms;
     a value that persists is a standing receive backlog on the client.
-  - `display X (pace A + latch B)` and `presents N` *(Android only)* — when the timeline presenter
-    is running it splits `display` in two: `pace` is the wait it deliberately holds the frame for
-    its target refresh, `latch` is SurfaceFlinger picking it up and scanning it out. `presents`
-    counts the frames confirmed on glass this second — well below `fps` means the presenter is
-    dropping or serializing frames; an `fps` shortfall with `presents` keeping up is upstream of
-    the client.
+  - `presents N` *(Android only)* — the frames confirmed on glass this second. Well below `fps`
+    means the presenter is dropping or serializing frames; an `fps` shortfall with `presents`
+    keeping up is upstream of the client.
+  - `display X (pace A + latch B)` *(Android, only when the floor couldn't be measured)* — with
+    the floor excluded, Android's `display` term is already just `pace` (the wait the presenter
+    deliberately holds a frame for its target refresh) and `latch` is what the `os present` line
+    reports. On the rare window where no latch sample pairs up, nothing is excluded and `display`
+    reverts to the raw figure with both halves shown.
 
   Against an **older host** that doesn't report its share yet, the first two terms
   merge into a single `host+network` number (`host+net` on Linux/Windows) — same total,
@@ -190,12 +203,13 @@ pretending:
 | Windows, Linux | `capture→on-glass` | present instant available (measured right after the Vulkan swapchain present); published raw |
 | macOS (Metal presenter) | `capture→on-glass` | present instant available (the system's on-glass time for the flip); published raw |
 | iOS/tvOS (Metal presenter) | `capture→on-glass` | present instant available, but the OS present floor is **excluded** from the number and printed separately as `os present +X.X excluded` |
-| Android | `capture→displayed` | MediaCodec's per-frame render callback reports SurfaceFlinger's render timestamp; on the rare window where no callback is delivered (the platform may drop them under load) the HUD falls back to `capture→decoded` |
+| Android | `capture→displayed` | MediaCodec's per-frame render callback reports SurfaceFlinger's render timestamp, and the OS present floor measured from it is **excluded** from the number and printed separately as `os present +X.X excluded`; on the rare window where no callback is delivered (the platform may drop them under load) the HUD falls back to `capture→decoded` |
 | macOS/iOS fallback presenter | `capture→received` | the system video layer hides decode and present timing entirely |
 
 A shorter chain means the number is **smaller because it measures less** — check the
 endpoint before comparing two devices, and add the excluded `os present` floor back to an
-iOS or tvOS client's headline before holding it next to another platform's.
+iOS, tvOS or Android client's headline before holding it next to a macOS, Linux or Windows
+one.
 
 ## Comparing with Moonlight / Sunshine
 
@@ -235,8 +249,8 @@ stands in for a one-way frame flight that Moonlight doesn't measure.)
 | `Frames dropped due to network jitter` | Decoded frames the *client's pacer* chose to drop ÷ decoded frames | `skipped` (line 4, Android only) | Approximately (both are client-side pacing decisions, despite Moonlight's name) |
 | `Average network latency` | The **control connection's round-trip time** (ENet RTT + variance) — not video frame latency | `network` (line 3) is the closest concept, but it's the *actual one-way frame path* (flight + reassembly), not an RTT | **No direct comparison.** Roughly, Punktfunk's `network` ≈ ½ × an idle RTT plus serialization time of the frame |
 | `Average decoding time` | Mean time from decoder enqueue to picture out | `decode` (p50) | Yes (mean vs median; both include decoder queueing) |
-| `Average frame queue delay` | Mean time a decoded frame waits for its vsync slot | inside `display` | Sum the two Moonlight lines → |
-| `Average rendering time (incl. V-sync latency)` | Mean duration of the present call | inside `display` | …and compare against Punktfunk's `display` |
+| `Average frame queue delay` *(desktop only)* | Mean time a decoded frame waits for its vsync slot | inside `display` | Sum the two Moonlight lines → |
+| `Average rendering time (incl. V-sync latency)` *(desktop only)* | Mean duration of the present call | inside `display` | …and compare against Punktfunk's `display` |
 | *(no equivalent)* | — | `end-to-end` — true capture→glass, clock-skew-corrected across machines | **Punktfunk only** |
 | *(no equivalent)* | — | `FEC` recovered shards (loss absorbed invisibly; Android only) | Punktfunk only |
 
@@ -250,6 +264,14 @@ Other differences worth knowing when squinting at both overlays side by side:
 - **Host frame rate.** Moonlight's headline FPS estimates what the *host* produced
   (received + lost). Punktfunk shows what your client actually received, and reports
   loss separately.
+- **On Android, Moonlight's numbers stop at the decoder.** The two lines above that cover
+  presentation are desktop-only: Moonlight's Android overlay measures nothing after the
+  decoder produces the picture, so no part of the wait for the screen appears anywhere in
+  it — and the popular Android forks measure the same slice. Its `Average decoding time` is
+  therefore comparable to Punktfunk's `decode`, and to nothing else; on Android there is no
+  Moonlight number that includes what your screen contributes. That asymmetry is why
+  Punktfunk excludes the `os present` floor on Android too, and why adding that floor back
+  is the right move when you want the whole truth rather than a like-for-like comparison.
 
 ## Recording a capture for a bug report
 

packaging/bazzite/build-sysext.sh

@@ -98,6 +98,23 @@ if [ -n "$GAMESCOPE" ]; then
   install -Dm0755 "$GAMESCOPE" "$STAGE/usr/bin/punktfunk-gamescope"
 fi
 
+# Enable the plugin/script runner for every user, by baking its `[Install] WantedBy=default.target`
+# symlink straight into the image.
+#
+# A sysext carries only /usr, and RPM scriptlets never run from one — so the `systemctl --global
+# enable` the .rpm/.deb do at install time has no equivalent here, and without this the runner would
+# ship present-but-off on exactly the platform (Bazzite / Fedora Atomic) where an operator is least
+# likely to go hunting for it. The game-library scanners are plugins now (design D9), so an
+# unenabled runner means an empty library.
+#
+# Opt-out is unchanged and still wins: `systemctl --user mask punktfunk-scripting` in the user's own
+# ~/.config/systemd/user takes precedence over anything under /usr.
+if [ -f "$STAGE/usr/lib/systemd/user/punktfunk-scripting.service" ]; then
+  install -d "$STAGE/usr/lib/systemd/user/default.target.wants"
+  ln -sf ../punktfunk-scripting.service \
+    "$STAGE/usr/lib/systemd/user/default.target.wants/punktfunk-scripting.service"
+fi
+
 # Self-update: the helper rides inside the image.
 install -Dm0755 "$HERE/punktfunk-sysext.sh" "$STAGE/usr/bin/punktfunk-sysext"
 

packaging/debian/build-scripting-deb.sh

@@ -114,20 +114,36 @@ Description: punktfunk plugin/script runner (Effect SDK on bun)
  capped-jittered restart; SIGTERM shuts the whole tree down structurally so plugin finalizers run).
  Bundles its own bun runtime (no system nodejs/bun dependency).
  .
- OPT-IN: the systemd --user unit is installed but not auto-enabled (the runner is inert until you add
- scripts or plugins). A plugin auto-wires to the host's mgmt token + identity cert on the same box —
- no env editing. Enable it with: systemctl --user enable --now punktfunk-scripting
+ ON BY DEFAULT: the systemd --user unit is enabled for every user (systemctl --global). The runner is
+ inert until you add scripts or plugins, and the game-library scanners now ship AS plugins — so a
+ host without the runner has an empty library and no obvious reason why. A plugin auto-wires to the
+ host's mgmt token + identity cert on the same box — no env editing.
+ Opt out per user with: systemctl --user mask punktfunk-scripting
 EOF
 
 cat > "$STAGE/DEBIAN/postinst" <<'EOF'
 #!/bin/sh
 set -e
 if [ "$1" = "configure" ]; then
-    echo "punktfunk-scripting installed. It runs your automation — add scripts to"
+    # `--global`, not `--user`: a maintainer script has no user session to act on, and this is the
+    # only mechanism that makes a `--user` unit on-by-default for everyone (it symlinks into
+    # /etc/systemd/user/…wants/). The library's scanners are plugins now, so the runner is a default
+    # component rather than an add-on (design D9) — but installing it stays opt-OUT, and the opt-out
+    # is `systemctl --user mask punktfunk-scripting`, since a plain `--user disable` cannot remove a
+    # global symlink.
+    #
+    # Only on FIRST configure ($2 empty): re-running it on every upgrade would silently undo the
+    # mask of anyone who turned it off.
+    if [ -z "$2" ] && command -v systemctl >/dev/null 2>&1; then
+        systemctl --global enable punktfunk-scripting.service >/dev/null 2>&1 || true
+    fi
+    echo "punktfunk-scripting installed and enabled for all users."
+    echo "It runs your automation — game-library sources, scripts in"
     echo "    ~/.config/punktfunk/scripts/  (loose .ts/.js files)"
-    echo "or install plugins into ~/.config/punktfunk/plugins/ (bun add punktfunk-plugin-<name>),"
-    echo "then enable the runner for your user:"
-    echo "    systemctl --user enable --now punktfunk-scripting"
+    echo "and plugins under ~/.config/punktfunk/plugins/."
+    echo "It starts with your next login; start it now with:"
+    echo "    systemctl --user start punktfunk-scripting"
+    echo "Don't want it? systemctl --user mask punktfunk-scripting"
 fi
 exit 0
 EOF

packaging/rpm/punktfunk.spec

@@ -191,9 +191,10 @@ The plugin/script runner for a punktfunk streaming host: it discovers loose scri
 ~/.config/punktfunk/scripts and installed punktfunk-plugin-* packages under ~/.config/punktfunk/
 plugins, and supervises each as an Effect fiber (capped-jittered restart; SIGTERM shuts the whole
 tree down structurally so plugin finalizers run). A plugin auto-wires to the host's mgmt token +
-identity cert on the same box — no env editing. Bundles its own bun runtime. OPT-IN: the systemd
---user unit ships disabled (the runner is inert until you add scripts/plugins). Enable with
-`systemctl --user enable --now punktfunk-scripting`.
+identity cert on the same box — no env editing. Bundles its own bun runtime. ON BY DEFAULT: the
+systemd --user unit is enabled for every user (systemctl --global). The game-library scanners ship
+as plugins, so a host without the runner has an empty library. Opt out per user with
+`systemctl --user mask punktfunk-scripting`.
 %endif
 
 %prep
@@ -599,10 +600,22 @@ echo "Then open https://<host-ip>:47992"
 
 %if %{with scripting}
 %post scripting
-echo "punktfunk-scripting installed. It runs your automation — add scripts to"
+# `--global`, not `--user`: a scriptlet has no user session to act on, and this is the only
+# mechanism that makes a `--user` unit on-by-default for everyone (it symlinks into
+# /etc/systemd/user/…wants/). The game-library scanners are plugins now, so the runner is a default
+# component rather than an add-on (design D9); it stays opt-OUT via
+# `systemctl --user mask punktfunk-scripting`, since a plain `--user disable` cannot remove a global
+# symlink. $1 == 1 is a first INSTALL — on an upgrade ($1 > 1) this must not undo an operator's mask.
+if [ "$1" -eq 1 ] && command -v systemctl >/dev/null 2>&1; then
+    systemctl --global enable punktfunk-scripting.service >/dev/null 2>&1 || :
+fi
+echo "punktfunk-scripting installed and enabled for all users."
+echo "It runs your automation — game-library sources, scripts in"
 echo "    ~/.config/punktfunk/scripts/  (loose .ts/.js files)"
-echo "or install plugins into ~/.config/punktfunk/plugins/ (bun add punktfunk-plugin-<name>),"
-echo "then enable the runner: systemctl --user enable --now punktfunk-scripting"
+echo "and plugins under ~/.config/punktfunk/plugins/."
+echo "It starts with your next login; start it now with:"
+echo "    systemctl --user start punktfunk-scripting"
+echo "Don't want it? systemctl --user mask punktfunk-scripting"
 %endif
 
 %changelog

packaging/windows/punktfunk-host.iss

@@ -329,9 +329,8 @@ Filename: "{app}\punktfunk-host.exe"; Parameters: "web setup {code:WebSetupParam
 ; converges tasks an older installer registered as SYSTEM.
 ; Best-effort (-ErrorAction SilentlyContinue): a task hiccup never fails the whole install. No braces
 ; in the command, so no Inno {{ }} escaping needed.
-Filename: "powershell.exe"; \
-  Parameters: "-NoProfile -ExecutionPolicy Bypass -Command ""$a=New-ScheduledTaskAction -Execute '{app}\scripting\scripting-run.cmd'; $t=New-ScheduledTaskTrigger -AtStartup; $p=New-ScheduledTaskPrincipal -UserId 'LocalService' -LogonType ServiceAccount; $s=New-ScheduledTaskSettingsSet -RestartCount 999 -RestartInterval (New-TimeSpan -Minutes 1) -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries; Register-ScheduledTask -TaskName PunktfunkScripting -Action $a -Trigger $t -Principal $p -Settings $s -Force -ErrorAction SilentlyContinue | Out-Null; Disable-ScheduledTask -TaskName PunktfunkScripting -ErrorAction SilentlyContinue | Out-Null"""; \
-  StatusMsg: "Registering the Punktfunk script runner (disabled; opt-in)..."; Flags: runhidden waituntilterminated
+Filename: "powershell.exe"; Parameters: "{code:ScriptingRegisterParams}"; \
+  StatusMsg: "Registering the Punktfunk script runner..."; Flags: runhidden waituntilterminated
 #endif
 #if defined(WithWeb) || defined(WithScripting)
 ; Put back what StopBunRuntimes disabled to unlock bun.exe. Deliberately the LAST [Run] entry that
@@ -619,6 +618,12 @@ end;
   it disabled would switch it off for everyone who had it on. }
 var
   WebTaskWasEnabled, ScriptingTaskWasEnabled: Boolean;
+  { Did PunktfunkScripting exist AT ALL before this install (enabled or not)? That is what
+    distinguishes a FRESH scripting install — where the runner is now registered enabled by default
+    (design D9: the library moves into plugins, and a flagship surface cannot depend on an opt-in
+    subsystem, or a fresh box would come up with an empty library) — from an UPGRADE, where the
+    operator's own choice is the only thing that may decide it. }
+  ScriptingTaskExisted: Boolean;
 
 { Escape a value for embedding in a single-quoted PowerShell literal ('' is PS's escaped quote).
   The install dir is user-chosen, so it can legitimately contain an apostrophe. }
@@ -643,6 +648,22 @@ begin
     Result := ResultCode = 1;
 end;
 
+{ Is the task registered at all, whatever its state? Distinct from TaskEnabled: an operator who
+  deliberately DISABLED the runner must keep it disabled across an upgrade, which is indistinguishable
+  from a fresh install if you only ask "was it enabled". }
+function TaskExists(TaskName: String): Boolean;
+var
+  ResultCode: Integer;
+begin
+  Result := False;
+  if Exec('powershell.exe',
+    '-NoProfile -ExecutionPolicy Bypass -Command "' +
+    '$t=Get-ScheduledTask -TaskName ''' + PsLiteral(TaskName) + ''' -ErrorAction SilentlyContinue; ' +
+    'if($t){exit 1}; exit 0"',
+    '', SW_HIDE, ewWaitUntilTerminated, ResultCode) then
+    Result := ResultCode = 1;
+end;
+
 { Free the bundled bun.exe (and the console's own files) BEFORE the copy. Windows will not delete a
   running image, so a surviving bun means "DeleteFile failed; code 5" on bun\bun.exe - the modal a
   user hit updating to 0.22.1.
@@ -664,6 +685,9 @@ var
 begin
   WebTaskWasEnabled := TaskEnabled('PunktfunkWeb');
   ScriptingTaskWasEnabled := TaskEnabled('PunktfunkScripting');
+  { Probed BEFORE the Disable below, which would otherwise make every upgrade look like a fresh
+    install to the registration entry. }
+  ScriptingTaskExisted := TaskExists('PunktfunkScripting');
   Exec('powershell.exe',
     '-NoProfile -ExecutionPolicy Bypass -Command "' +
     '$ErrorActionPreference=''SilentlyContinue''; ' +
@@ -689,6 +713,35 @@ end;
   DELETED the legacy task (the console runs under the host service now), so Enable-ScheduledTask
   hits nothing and no-ops under SilentlyContinue. If the user cancels mid-install, though,
   DeinitializeSetup runs this same restore and puts the old (task-owned) world back intact. }
+{ Register PunktfunkScripting, and decide whether it comes up ENABLED.
+  `Register-ScheduledTask` registers enabled, so the state is decided by what follows:
+    * FRESH install (the task did not exist) -> leave it enabled and start it now, so the runner is
+      live without waiting for a reboot. Since the library's scanners become plugins (design D9),
+      shipping this opt-in would mean a fresh box comes up with an empty library and no obvious
+      reason why.
+    * UPGRADE (the task existed) -> disable here and let RestoreTasksParams put the operator's own
+      state back. That order is deliberate: this entry cannot know what they chose, and defaulting
+      to "on" here would silently switch the runner on for everyone who had turned it off.
+  It remains opt-OUT: `punktfunk-host plugins disable`, or the task's own Disable, still wins and
+  survives every later upgrade through exactly this path. }
+function ScriptingRegisterParams(Param: String): String;
+begin
+  Result := '-NoProfile -ExecutionPolicy Bypass -Command "' +
+    '$ErrorActionPreference=''SilentlyContinue''; ' +
+    '$a=New-ScheduledTaskAction -Execute ''' +
+      PsLiteral(ExpandConstant('{app}\scripting\scripting-run.cmd')) + '''; ' +
+    '$t=New-ScheduledTaskTrigger -AtStartup; ' +
+    '$p=New-ScheduledTaskPrincipal -UserId ''LocalService'' -LogonType ServiceAccount; ' +
+    '$s=New-ScheduledTaskSettingsSet -RestartCount 999 -RestartInterval (New-TimeSpan -Minutes 1) ' +
+      '-AllowStartIfOnBatteries -DontStopIfGoingOnBatteries; ' +
+    'Register-ScheduledTask -TaskName PunktfunkScripting -Action $a -Trigger $t -Principal $p ' +
+      '-Settings $s -Force | Out-Null; ';
+  if ScriptingTaskExisted then
+    Result := Result + 'Disable-ScheduledTask -TaskName PunktfunkScripting | Out-Null"'
+  else
+    Result := Result + 'Start-ScheduledTask -TaskName PunktfunkScripting | Out-Null"';
+end;
+
 function RestoreTasksParams(Param: String): String;
 begin
   Result := '-NoProfile -ExecutionPolicy Bypass -Command "$ErrorActionPreference=''SilentlyContinue''; ';

plugin-kit/README.md

@@ -53,6 +53,41 @@ export default definePluginKit({
 | `loggingLayer` | runner-journal line format |
 | `@punktfunk/plugin-kit/react` | browser glue: `createPluginRouter` (path→hash→fallback deep-link restore + `pf-ui:navigate`), `resolvePluginBase`, `useIsEmbedded`, `ResultGate`, `sseAtom` |
 | `@punktfunk/plugin-kit/theme.css` | the console's violet identity for plugin UIs (import first in your Tailwind entry) |
+| `@punktfunk/plugin-kit/library` | everything a **game-library scanner** plugin needs — see below |
+
+## Library-scanner plugins (`@punktfunk/plugin-kit/library`)
+
+The six first-party scanners (steam, lutris, heroic, epic, gog, xbox) each live in **their own
+repo**, like every other punktfunk plugin. Nothing is lost by that split because everything they
+share is published here rather than sitting adjacent to them:
+
+| Export | What it saves you writing |
+| --- | --- |
+| `defineLibraryPlugin` | the whole plugin except the scan: store claim, sync engine (poll + fs-watch + debounce), launcher entries, `__config`, `category: "library"` registration, and the `detect` / `scan` / `parity` / `uninstall` CLI verbs |
+| `parsers/*` | text VDF + `.acf`, binary `shortcuts.vdf` (with the CRC-32 appid and the 64-bit `rungameid` composition), read-only SQLite, `reg.exe`, capped readers, a confined path join, Steam root/library discovery, art location helpers, an anti-SSRF fetch |
+| `diffParity` + the `parity` verb | the acceptance gate below |
+
+A first-party scanner is therefore **its parsers and a `scan` function** — a few hundred lines.
+
+### The parity gate
+
+Ported unit tests pin the parsers; they do not prove the plugin reproduces the scanner it replaces.
+A plugin that parses perfectly and emits `steam:440.0` instead of `steam:440` breaks every Moonlight
+pin on the host, and no parser test notices. So, on a box with that launcher installed:
+
+```sh
+# 1. while the host is still using its BUILT-IN scanner:
+punktfunk-plugin-steam parity --snapshot before.json
+# 2. offline — runs this plugin's own scan and diffs:
+punktfunk-plugin-steam parity --compare before.json
+```
+
+`--compare` exits non-zero on any difference, so it works as a release gate. It compares ids,
+titles, launch recipes, roles and metadata exactly; **art by presence, not value** (the
+representation legitimately changes — a host-relative proxy path or inlined `data:` URL becomes a
+`file://` path or a CDN URL), so spot-check a few covers by eye once. Launcher entries the plugin
+adds are reported separately rather than failing the run; an ordinary title the scanner never had
+still fails.
 
 ## Telling the host how to recognize a running title (`detect`)
 

plugin-kit/examples/lutris-plugin.ts

@@ -0,0 +1,168 @@
+// A COMPLETE library-scanner plugin, and the template the six first-party ones are cut from.
+//
+// This is the lutris pilot (design M5/WP5.1) — the smallest of the six, and the one that exercises
+// the POSIX local-art path end to end. It lives here as a worked example rather than shipped code:
+// each scanner gets its OWN repo (the house pattern), and this is what you copy into a fresh one.
+// `package.json`'s `files` is dist + README, so nothing here is published.
+//
+// The point it proves: everything below the `scan` function is store-specific parsing, and
+// everything else — the store claim, the sync engine, launcher entries, `__config`, the console
+// registration, the CLI verbs including the parity gate — comes from `defineLibraryPlugin`. That is
+// what makes six repos cost nothing in duplication.
+//
+// Ported from crates/punktfunk-host/src/library/lutris.rs, with two deliberate changes:
+//   * art is emitted as `file://` URLs instead of inlined `data:` URLs. The host proxies the bytes,
+//     so the reconcile payload stays tiny — inlining covers is what blew the host's 2 MB body limit
+//     at 49 titles during the playnite work, and it is exactly why the POSIX art path exists (G4).
+//   * the `installed = 1` filter and the untrusted-slug guard are carried over verbatim. The slug
+//     comes from Lutris's own database and is interpolated into a path, so the guard is load-bearing.
+import * as os from "node:os";
+import * as path from "node:path";
+import { Effect, Schema } from "effect";
+import {
+	defineLibraryPlugin,
+	fileUrl,
+	isFile,
+	withReadOnlyDb,
+} from "../src/library/index.js";
+import type { ProviderEntry } from "../src/wire.js";
+
+const LutrisConfig = Schema.Struct({
+	/**
+	 * Where `pga.db` lives, when it isn't in one of the standard places. Annotated because the
+	 * console's generic settings form derives its label and help text from exactly these.
+	 */
+	databasePath: Schema.optionalKey(
+		Schema.String.annotate({
+			title: "Lutris database",
+			description:
+				"Absolute path to pga.db. Leave empty to find it automatically.",
+		}),
+	),
+});
+
+/** Candidate `pga.db` locations: XDG data dir, the classic path, Flatpak. */
+const databaseCandidates = (): string[] => {
+	const out: string[] = [];
+	const xdg = process.env.XDG_DATA_HOME;
+	if (xdg) out.push(path.join(xdg, "lutris/pga.db"));
+	const home = os.homedir();
+	if (home) {
+		out.push(path.join(home, ".local/share/lutris/pga.db"));
+		out.push(path.join(home, ".var/app/net.lutris.Lutris/data/lutris/pga.db"));
+	}
+	return out;
+};
+
+const findDatabase = (cfg: { databasePath?: string }): string | undefined =>
+	[...(cfg.databasePath ? [cfg.databasePath] : []), ...databaseCandidates()].find(
+		isFile,
+	);
+
+/**
+ * `<kind>/<slug>.jpg` across the current, legacy-cache and Flatpak Lutris roots.
+ *
+ * The slug comes verbatim from Lutris's database and is interpolated into a path, so a separator,
+ * parent ref or NUL is refused — otherwise a crafted slug is an arbitrary-file-read primitive, and
+ * the resulting path would be handed to the host's art proxy to serve (security-review 2026-07-17).
+ * Real Lutris slugs are `[a-z0-9-]`.
+ */
+const artFile = (kind: string, slug: string): string | undefined => {
+	if (
+		slug === "" ||
+		slug.includes("/") ||
+		slug.includes("\\") ||
+		slug.includes("..") ||
+		slug.includes("\0")
+	) {
+		return undefined;
+	}
+	const home = os.homedir();
+	if (!home) return undefined;
+	const roots = [
+		path.join(home, ".local/share/lutris"),
+		path.join(home, ".cache/lutris"),
+		path.join(home, ".var/app/net.lutris.Lutris/data/lutris"),
+		path.join(home, ".var/app/net.lutris.Lutris/cache/lutris"),
+	];
+	for (const root of roots) {
+		const p = path.join(root, kind, `${slug}.jpg`);
+		if (isFile(p)) return p;
+	}
+	return undefined;
+};
+
+interface GameRow {
+	id: number;
+	slug: string | null;
+	name: string;
+	directory: string | null;
+}
+
+export default defineLibraryPlugin({
+	// One string: plugin id, provider id, store claim, and the id of the built-in scanner this
+	// replaces. That identity chain is what keeps entry ids, GameStream app ids and the operator's
+	// existing enable/disable state intact across the migration.
+	name: "lutris",
+	configSchema: LutrisConfig,
+
+	detect: (cfg) => Effect.sync(() => findDatabase(cfg) !== undefined),
+
+	scan: (cfg) =>
+		Effect.sync(() => {
+			const db = findDatabase(cfg);
+			if (!db) return [];
+			// Read-only + immutable: a running Lutris holding the file can neither block us nor be
+			// disturbed by us.
+			const rows =
+				withReadOnlyDb(db, (h) =>
+					// `directory` is our only detect signal but is not load-bearing for the library, so
+					// a schema without it must not cost the whole source — the helper answers [] on a
+					// bad query, and the fallback keeps the titles.
+					h.query<GameRow>(
+						"SELECT id, slug, name, directory FROM games " +
+							"WHERE installed = 1 AND name IS NOT NULL AND name <> '' " +
+							"ORDER BY name COLLATE NOCASE",
+					),
+				) ?? [];
+			const usable =
+				rows.length > 0
+					? rows
+					: (withReadOnlyDb(db, (h) =>
+							h.query<GameRow>(
+								"SELECT id, slug, name, NULL AS directory FROM games " +
+									"WHERE installed = 1 AND name IS NOT NULL AND name <> '' " +
+									"ORDER BY name COLLATE NOCASE",
+							),
+						) ?? []);
+
+			return usable.map((row): ProviderEntry => {
+				const portrait = row.slug ? artFile("coverart", row.slug) : undefined;
+				const header = row.slug ? artFile("banners", row.slug) : undefined;
+				const dir = row.directory?.trim();
+				return {
+					// The host composes `lutris:<external_id>` — byte-identical to what the built-in
+					// scanner produced, which the parity gate checks.
+					external_id: String(row.id),
+					title: row.name,
+					launch: { kind: "lutris_id", value: String(row.id) },
+					art: {
+						...(portrait ? { portrait: fileUrl(portrait) } : {}),
+						...(header ? { header: fileUrl(header) } : {}),
+					},
+					// Lutris stamps no per-game env marker worth relying on, so the install dir is the
+					// whole recipe; a game with none (an emulator entry pointing at a bare ROM) stays
+					// untracked, exactly as it did in-host.
+					...(dir ? { detect: { install_dir: dir } } : {}),
+					platform: "PC",
+				};
+			});
+		}),
+
+	// Re-scan when Lutris writes: installing a game touches the database, and downloading art
+	// touches the cover directories.
+	watchDirs: (cfg) => {
+		const db = findDatabase(cfg);
+		return db ? [path.dirname(db)] : [];
+	},
+});

plugin-kit/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@punktfunk/plugin-kit",
-	"version": "0.2.0",
+	"version": "0.3.0",
 	"description": "Effect-based framework for punktfunk plugins: lifecycle runtime, config/state, sync engine, UI serving, CLI scaffold, and browser helpers.",
 	"type": "module",
 	"license": "MIT OR Apache-2.0",
@@ -29,6 +29,10 @@
 			"types": "./dist/wire.d.ts",
 			"default": "./dist/wire.js"
 		},
+		"./library": {
+			"types": "./dist/library/index.d.ts",
+			"default": "./dist/library/index.js"
+		},
 		"./theme.css": "./dist/theme.css"
 	},
 	"files": ["dist", "README.md"],

plugin-kit/src/index.ts

@@ -43,6 +43,13 @@ export {
 	type SyncSettings,
 	type SyncStatus,
 } from "./sync-engine.js";
-export { httpApiEnv, serveUi, type ServeUiOptions } from "./ui-server.js";
+export {
+	deriveConfigJsonSchema,
+	httpApiEnv,
+	makeConfigHandler,
+	serveUi,
+	type ServeUiConfig,
+	type ServeUiOptions,
+} from "./ui-server.js";
 export { sseRoute, type SseRouteOptions } from "./sse.js";
 export { type CliCommand, runPluginCli } from "./cli.js";

plugin-kit/src/library/define.ts

@@ -0,0 +1,335 @@
+// `defineLibraryPlugin` — the shared framework behind every library-scanner plugin (design D10).
+//
+// The point of this module is that a first-party scanner should be **its parsers and a scan
+// function**, ~200–400 lines, and nothing else. Everything a scanner needs beyond that is identical
+// across all six of them and lives here: claiming the store, reconciling through the sync engine,
+// appending launcher entries, serving `__config` so the console renders settings without the plugin
+// shipping an SPA, registering under `category: "library"` so it stays out of the nav, and the
+// standard CLI verbs.
+import type { PluginDef } from "@punktfunk/host";
+import * as fs from "node:fs";
+import { Duration, Effect, Layer, Schema, Stream } from "effect";
+import { type CliCommand, runPluginCli } from "../cli.js";
+import { type ConfigService, makeConfigService } from "../config.js";
+import { HostClient, PluginInfo } from "../host-client.js";
+import { ProviderClient, type ProviderClientService } from "../reconcile.js";
+import { definePluginKit, type PluginKitDef } from "../runtime.js";
+import { makeSyncEngine } from "../sync-engine.js";
+import { serveUi } from "../ui-server.js";
+import type { ProviderEntry } from "../wire.js";
+import {
+	diffParity,
+	formatParityReport,
+	fromHostEntry,
+	fromProviderEntry,
+	type HostGameEntry,
+} from "./parity.js";
+
+/** What a scan produced — the status surface and the CLI's `scan` verb both render this. */
+export interface ScanReport {
+	readonly entries: number;
+	readonly launchers: number;
+	/** False when the launcher isn't installed here — the library is legitimately empty. */
+	readonly present: boolean;
+}
+
+export interface LibraryPluginDef<S extends Schema.Top> {
+	/**
+	 * The plugin id. **This one string is also the provider id, the store claim, and the id of the
+	 * built-in scanner this plugin replaces.** That identity chain is what makes the migration
+	 * invisible: entry ids stay `<name>:<external_id>`, GameStream app ids and client art caches
+	 * stay valid, and the operator's existing enable/disable state carries over untouched.
+	 */
+	readonly name: string;
+	readonly version?: string;
+	/**
+	 * The store to claim (design D2). Defaults to {@link name} and should almost never differ — see
+	 * the identity note above. Pass `null` to opt out of claiming entirely, which makes this an
+	 * ordinary unclaimed provider whose entries surface as `custom:`.
+	 */
+	readonly store?: string | null;
+	/** The operator-facing config schema. Drives `__config` and every callback's argument. */
+	readonly configSchema: S;
+	/**
+	 * Is this launcher present on the host at all? Surfaces in the CLI's `detect` verb, and lets the
+	 * plugin report "not installed" rather than silently syncing an empty library.
+	 */
+	readonly detect: (cfg: S["Type"]) => Effect.Effect<boolean>;
+	/** Enumerate the launcher's installed titles — the only real per-store code. */
+	readonly scan: (
+		cfg: S["Type"],
+	) => Effect.Effect<ReadonlyArray<ProviderEntry>>;
+	/**
+	 * Entries that open the LAUNCHER itself (design D4) — Steam Big Picture, Heroic, … Appended to
+	 * every reconcile, so toggling one in config takes effect on the next sync. Emit them with
+	 * `role: "launcher"`; the kit does not stamp it for you, because a plugin may legitimately want
+	 * an entry that opens a launcher but still lists as an ordinary game.
+	 */
+	readonly launchers?: (cfg: S["Type"]) => ReadonlyArray<ProviderEntry>;
+	/** Launcher data dirs to watch, so a newly installed game appears without waiting for a poll. */
+	readonly watchDirs?: (cfg: S["Type"]) => ReadonlyArray<string>;
+	/** How often to re-scan regardless of watches. Default `Duration.minutes(15)`. */
+	readonly pollInterval?: Duration.Duration;
+	/** Debounce on filesystem events. Default `Duration.seconds(3)`. */
+	readonly debounce?: Duration.Duration;
+	/** Display title (the console's sources row falls back to the scanner label). Defaults to `name`. */
+	readonly title?: string;
+	/** Extra CLI verbs beyond the standard `detect` / `scan` / `uninstall` set. */
+	readonly commands?: Record<string, CliCommand<never>>;
+}
+
+/** `--flag value` from an argv slice, or undefined. */
+const flagValue = (
+	argv: ReadonlyArray<string>,
+	flag: string,
+): string | undefined => {
+	const i = argv.indexOf(flag);
+	return i >= 0 && i + 1 < argv.length ? argv[i + 1] : undefined;
+};
+
+/** The pieces a library plugin package wires into its entry points. */
+export interface LibraryPlugin {
+	/** The runner-discovered default export (`export default plugin.def`). */
+	readonly def: PluginDef;
+	/** The CLI entry (`await plugin.cli()` from the package's bin). */
+	readonly cli: (argv?: ReadonlyArray<string>) => Promise<void>;
+}
+
+export const defineLibraryPlugin = <S extends Schema.Top>(
+	def: LibraryPluginDef<S>,
+): LibraryPlugin => {
+	const store = def.store === null ? undefined : (def.store ?? def.name);
+	const poll = def.pollInterval ?? Duration.minutes(15);
+	const debounce = def.debounce ?? Duration.seconds(3);
+
+	/** The config service, built fresh wherever it is needed (it only requires `PluginInfo`). */
+	const config: Effect.Effect<ConfigService<S>, never, PluginInfo> =
+		makeConfigService({ schema: def.configSchema });
+
+	/** Scan + launcher entries, in the order they should reach the host. */
+	const computeEntries = (
+		cfg: S["Type"],
+	): Effect.Effect<{
+		readonly entries: ReadonlyArray<ProviderEntry>;
+		readonly report: ScanReport;
+	}> =>
+		Effect.gen(function* () {
+			const present = yield* def.detect(cfg);
+			// A launcher that isn't installed contributes NOTHING — not even its launcher entries. A
+			// "Steam Big Picture" tile on a box without Steam would only fail to launch.
+			if (!present) {
+				return {
+					entries: [] as ReadonlyArray<ProviderEntry>,
+					report: { entries: 0, launchers: 0, present: false } as const,
+				};
+			}
+			const scanned = yield* def.scan(cfg);
+			const launchers = def.launchers?.(cfg) ?? [];
+			return {
+				entries: [...scanned, ...launchers],
+				report: {
+					entries: scanned.length,
+					launchers: launchers.length,
+					present: true,
+				} as const,
+			};
+		});
+
+	/**
+	 * Push one entry set to the host under the store claim, warning **once** if the host is too old
+	 * to honour it.
+	 *
+	 * This degradation is worth the code: a pre-M2 host ignores `?store=` silently, and the only
+	 * symptom would be this plugin's titles appearing as unbadged `custom:` entries *beside* the
+	 * built-in scanner's identical ones — a confusing double-listing with no error anywhere.
+	 * Checking the echoed entries turns that into one actionable log line.
+	 */
+	const applyEntries =
+		(provider: ProviderClientService, state: { warned: boolean }) =>
+		(entries: ReadonlyArray<ProviderEntry>): Effect.Effect<void, unknown> =>
+			provider.reconcile(def.name, entries, store).pipe(
+				Effect.tap((echoed) => {
+					if (!store || state.warned || echoed.length === 0) return Effect.void;
+					if (echoed.some((e) => e.store === store)) return Effect.void;
+					state.warned = true;
+					return Effect.logWarning(
+						`host is too old for store claims: this source's games will appear as custom ` +
+							`entries and the host's own "${store}" scanner is not suppressed, so titles ` +
+							`may be listed twice. Updating the host resolves it.`,
+					);
+				}),
+				Effect.asVoid,
+			);
+
+	const main = Effect.gen(function* () {
+		const cfgService = yield* config;
+		const provider = yield* ProviderClient;
+		const state = { warned: false };
+
+		const engine = yield* makeSyncEngine<
+			ScanReport,
+			ReadonlyArray<ProviderEntry>,
+			never
+		>({
+			compute: () => cfgService.load.pipe(Effect.flatMap(computeEntries)),
+			apply: applyEntries(provider, state),
+			// The host IS the state: a full-replace reconcile is idempotent, so there is nothing to
+			// persist between runs. Reporting no previous fingerprint means the first sync after a
+			// restart always pushes, which is exactly what we want (the host may have been reinstalled
+			// underneath us).
+			lastSync: { get: Effect.succeed(undefined), set: () => Effect.void },
+			settings: cfgService.load.pipe(
+				Effect.map((cfg) => def.watchDirs?.(cfg) ?? []),
+				// A config file that won't decode must not stop the poll loop: fall back to no watch
+				// dirs, keep syncing on the timer, and let the operator see the parse error in the
+				// settings drawer (`GET /__config` reports it).
+				Effect.catch(() => Effect.succeed([] as ReadonlyArray<string>)),
+				Effect.map((watchDirs) => ({
+					pollInterval: poll,
+					watch: true,
+					debounce,
+					watchDirs,
+				})),
+			),
+		});
+
+		// The UI server exists ONLY to serve `__config` (and the SDK's `__health`): no `staticDir`,
+		// no API. That is the whole "settings without an SPA" story (design D7, closing G8), and the
+		// `library` category is what keeps six installed scanners out of the console's sidebar.
+		yield* serveUi({
+			title: def.title ?? def.name,
+			category: "library",
+			config: { schema: def.configSchema, service: cfgService },
+		});
+
+		yield* engine.start;
+		// A saved settings change is exactly when a user expects the library to update — and it may
+		// have changed `watchDirs`, so re-read settings rather than just re-syncing.
+		yield* Effect.forkScoped(
+			Stream.runForEach(cfgService.changes, () => engine.reconfigure),
+		);
+		yield* Effect.never;
+	});
+
+	const kitDef: PluginKitDef<never, ProviderClient> = {
+		name: def.name,
+		...(def.version !== undefined ? { version: def.version } : {}),
+		layer: ProviderClient.layer,
+		main: main as Effect.Effect<
+			void,
+			never,
+			ProviderClient | HostClient | PluginInfo | never
+		>,
+	};
+
+	const standardCommands: Record<string, CliCommand<ProviderClient>> = {
+		detect: {
+			summary: "report whether this launcher is installed on the host",
+			// Offline on purpose: "is Steam here?" must be answerable without a running host.
+			offline: true,
+			run: () =>
+				Effect.gen(function* () {
+					const cfg = yield* (yield* config).load;
+					console.log((yield* def.detect(cfg)) ? "present" : "absent");
+				}),
+		},
+		scan: {
+			summary: "scan and print what WOULD be synced (--preview for the JSON entries)",
+			// Also offline: the point is to debug a scanner against real launcher files without
+			// touching the host's library.
+			offline: true,
+			run: (argv) =>
+				Effect.gen(function* () {
+					const cfg = yield* (yield* config).load;
+					const { entries, report } = yield* computeEntries(cfg);
+					if (argv.includes("--preview")) {
+						console.log(JSON.stringify(entries, null, 2));
+					} else {
+						console.log(
+							`${report.present ? "present" : "absent"}: ${report.entries} games, ` +
+								`${report.launchers} launcher entries`,
+						);
+					}
+				}),
+		},
+		parity: {
+			summary:
+				"prove this plugin reproduces the built-in scanner (--snapshot <f> | --compare <f>)",
+			// `--compare` is offline (it runs THIS plugin's scan); `--snapshot` needs the host. The
+			// dispatcher decides per invocation below, so the verb is registered as online and the
+			// snapshot path is the one that actually uses the client.
+			run: (argv) =>
+				Effect.gen(function* () {
+					const snapshot = flagValue(argv, "--snapshot");
+					const compare = flagValue(argv, "--compare");
+					if (!snapshot && !compare) {
+						console.error(
+							"usage: parity --snapshot <file>   (capture the host's CURRENT library for this store)\n" +
+								"       parity --compare  <file>   (diff this plugin's scan against that capture)",
+						);
+						process.exitCode = 2;
+						return;
+					}
+					if (snapshot) {
+						// The baseline: what the host reports for THIS store while its built-in scanner
+						// is still the thing producing it. Capture before installing the plugin.
+						const host = yield* HostClient;
+						const body = yield* host.request("GET", "/library");
+						const mine = (Array.isArray(body) ? (body as HostGameEntry[]) : [])
+							.filter((e) => e.store === (store ?? def.name))
+							.map(fromHostEntry)
+							.sort((a, b) => a.id.localeCompare(b.id));
+						yield* Effect.sync(() =>
+							fs.writeFileSync(snapshot, `${JSON.stringify(mine, null, 2)}\n`),
+						);
+						console.log(
+							`captured ${mine.length} "${store ?? def.name}" entries to ${snapshot}`,
+						);
+						return;
+					}
+					const baseline = yield* Effect.try({
+						try: () =>
+							JSON.parse(fs.readFileSync(compare as string, "utf8")) as ReturnType<
+								typeof fromHostEntry
+							>[],
+						catch: (cause) => new Error(`cannot read ${compare}: ${cause}`),
+					});
+					const cfg = yield* (yield* config).load;
+					const { entries } = yield* computeEntries(cfg);
+					const produced = entries.map((e) =>
+						fromProviderEntry(store ?? def.name, e),
+					);
+					const report = diffParity(baseline, produced);
+					console.log(formatParityReport(report));
+					// A non-zero exit is what makes this usable as a release gate rather than a report
+					// somebody skims.
+					if (!report.ok) process.exitCode = 1;
+				}),
+		},
+		uninstall: {
+			summary: "remove this source's games from the host and release its store claim",
+			run: () =>
+				Effect.gen(function* () {
+					const provider = yield* ProviderClient;
+					// The empty reconcile clears the entries; DELETE is what releases the CLAIM — and
+					// releasing is what brings the host's own built-in scanner straight back.
+					yield* provider.reconcile(def.name, [], undefined);
+					yield* provider.remove(def.name);
+					console.log(`${def.name}: entries removed, store claim released`);
+				}),
+		},
+	};
+
+	return {
+		def: definePluginKit(kitDef),
+		cli: (argv) =>
+			runPluginCli({
+				def: kitDef,
+				commands: {
+					...standardCommands,
+					...(def.commands ?? {}),
+				} as Record<string, CliCommand<ProviderClient>>,
+				...(argv !== undefined ? { argv } : {}),
+			}),
+	};
+};

plugin-kit/src/library/index.ts

@@ -0,0 +1,23 @@
+// `@punktfunk/plugin-kit/library` — the shared framework for library-scanner plugins.
+//
+// A first-party scanner is its parsers plus a scan function; everything else (store claim, sync
+// engine wiring, launcher entries, `__config`, nav category, CLI verbs) comes from
+// `defineLibraryPlugin`. See design/library-scanner-plugins.md D10.
+export {
+	defineLibraryPlugin,
+	type LibraryPlugin,
+	type LibraryPluginDef,
+	type ScanReport,
+} from "./define.js";
+export {
+	claimedLibraryId,
+	diffParity,
+	formatParityReport,
+	fromHostEntry,
+	fromProviderEntry,
+	type HostGameEntry,
+	type ParityChange,
+	type ParityEntry,
+	type ParityReport,
+} from "./parity.js";
+export * from "./parsers/index.js";

plugin-kit/src/library/parity.ts

@@ -0,0 +1,249 @@
+// The parity harness: proof that a library plugin reproduces the in-host scanner it replaces.
+//
+// This is the acceptance gate for every extracted scanner (design M5). Ported unit tests are
+// necessary but nowhere near sufficient — they pin the PARSERS, while what actually has to hold is
+// that the whole pipeline lands the same entries, with the same ids, launch recipes and detect
+// signals, on a real box with a real launcher installed. A plugin that parses perfectly and emits
+// `steam:440` as `steam:440.0` breaks every Moonlight pin on the host and no parser test notices.
+//
+// It lives in the KIT, not in a plugin, because it is identical for all six: capture what the host
+// reports while its built-in scanner is doing the work, then check the plugin produces the same set.
+// (One plugin per repo is the house pattern, so anything shared has to be published, not adjacent.)
+//
+// Usage, per plugin, on a box with that launcher installed:
+//
+//   punktfunk-plugin-steam parity --snapshot before.json   # host still on its built-in scanner
+//   punktfunk-plugin-steam parity --compare before.json    # offline: runs THIS plugin's scan
+//
+// `--compare` runs the plugin's own scan directly rather than installing it first, so a mismatch is
+// visible before anything is published — and the run is repeatable while you fix it.
+import type { ProviderEntry } from "../wire.js";
+
+/** The four art slots, in the order the host's box-art ladder tries them. */
+const ART_KINDS = ["portrait", "hero", "logo", "header"] as const;
+type ArtKind = (typeof ART_KINDS)[number];
+
+/** One entry, reduced to the facts parity is about. */
+export interface ParityEntry {
+	/** The store-qualified library id — the field everything downstream is keyed on. */
+	readonly id: string;
+	readonly title: string;
+	/** `<kind>:<value>`, or null when the entry has no launch recipe. */
+	readonly launch: string | null;
+	/** `"game"` or `"launcher"`. */
+	readonly role: string;
+	/**
+	 * Which art kinds are PRESENT, not their values. The representation legitimately changes on
+	 * extraction (a scanner's `data:` URL or host-relative proxy path becomes a `file://` path or a
+	 * CDN URL), so comparing values would fail every time for no reason. Presence is the invariant
+	 * that matters: a title that had a poster must still have one.
+	 */
+	readonly art: Readonly<Record<ArtKind, boolean>>;
+	/** Flat descriptive metadata (platform, genres, …) — compared verbatim. */
+	readonly meta: Readonly<Record<string, unknown>>;
+}
+
+/** What the host reports for one entry in `GET /library`. */
+export interface HostGameEntry {
+	id: string;
+	store: string;
+	title: string;
+	role?: string;
+	launch?: { kind: string; value: string } | null;
+	art?: Partial<Record<ArtKind, string | null>>;
+	[extra: string]: unknown;
+}
+
+/** Keys on a host entry that are structure, not descriptive metadata. */
+const NON_META = new Set([
+	"id",
+	"store",
+	"title",
+	"role",
+	"launch",
+	"art",
+	"provider",
+	"external_id",
+	"prep",
+	"detect",
+]);
+
+const artPresence = (
+	art: Partial<Record<ArtKind, string | null>> | undefined,
+): Record<ArtKind, boolean> => {
+	const out = {} as Record<ArtKind, boolean>;
+	for (const k of ART_KINDS) out[k] = Boolean(art?.[k]);
+	return out;
+};
+
+const pickMeta = (src: Record<string, unknown>): Record<string, unknown> => {
+	const out: Record<string, unknown> = {};
+	for (const [k, v] of Object.entries(src)) {
+		// Absent and empty are the same thing here: the host omits empty lists and null fields, and a
+		// plugin that sends `genres: []` has not changed anything.
+		if (NON_META.has(k) || v == null) continue;
+		if (Array.isArray(v) && v.length === 0) continue;
+		out[k] = v;
+	}
+	return out;
+};
+
+/** The library id the host assigns a claimed entry — the deterministic `<store>:<external_id>`. */
+export const claimedLibraryId = (store: string, externalId: string): string =>
+	`${store}:${externalId}`;
+
+/** Reduce what the host reported (the BEFORE side) to a comparable entry. */
+export const fromHostEntry = (e: HostGameEntry): ParityEntry => ({
+	id: e.id,
+	title: e.title,
+	launch: e.launch ? `${e.launch.kind}:${e.launch.value}` : null,
+	role: e.role ?? "game",
+	art: artPresence(e.art),
+	meta: pickMeta(e as Record<string, unknown>),
+});
+
+/** Reduce what this plugin produced (the AFTER side) to a comparable entry. */
+export const fromProviderEntry = (
+	store: string,
+	e: ProviderEntry,
+): ParityEntry => {
+	const rec = e as unknown as Record<string, unknown>;
+	return {
+		id: claimedLibraryId(store, e.external_id),
+		title: e.title,
+		launch: e.launch ? `${e.launch.kind}:${e.launch.value}` : null,
+		role: (e as { role?: string }).role ?? "game",
+		art: artPresence(
+			e.art as Partial<Record<ArtKind, string | null>> | undefined,
+		),
+		meta: pickMeta(rec),
+	};
+};
+
+/** One field that differs between the two sides. */
+export interface ParityChange {
+	readonly id: string;
+	readonly field: string;
+	readonly before: unknown;
+	readonly after: unknown;
+}
+
+export interface ParityReport {
+	/** In the baseline, absent from what the plugin produced — the plugin LOST a title. */
+	readonly missing: ParityEntry[];
+	/** Produced by the plugin, absent from the baseline — the plugin invented a title. */
+	readonly extra: ParityEntry[];
+	/** Same id, different facts. */
+	readonly changed: ParityChange[];
+	/** Entries present on both sides and identical. */
+	readonly matched: number;
+	/**
+	 * Launcher entries the plugin adds (design D4). Never a failure: the built-in scanner had no
+	 * concept of them, so they are expected to be `extra` and are reported separately so a real
+	 * regression isn't buried under them.
+	 */
+	readonly launchersAdded: ParityEntry[];
+	readonly ok: boolean;
+}
+
+/**
+ * Diff a baseline (what the host reported while its built-in scanner ran) against what this plugin
+ * produced. `ok` is true only when nothing is missing, nothing unexpected is extra, and no compared
+ * field changed.
+ */
+export const diffParity = (
+	baseline: ReadonlyArray<ParityEntry>,
+	produced: ReadonlyArray<ParityEntry>,
+): ParityReport => {
+	const byId = new Map(baseline.map((e) => [e.id, e]));
+	const producedIds = new Set(produced.map((e) => e.id));
+	const changed: ParityChange[] = [];
+	const extra: ParityEntry[] = [];
+	const launchersAdded: ParityEntry[] = [];
+	let matched = 0;
+
+	for (const after of produced) {
+		const before = byId.get(after.id);
+		if (!before) {
+			// A launcher entry has no counterpart by construction — the scanner never emitted one.
+			(after.role === "launcher" ? launchersAdded : extra).push(after);
+			continue;
+		}
+		const diffs = compareEntry(before, after);
+		if (diffs.length === 0) matched++;
+		else changed.push(...diffs);
+	}
+
+	const missing = baseline.filter((e) => !producedIds.has(e.id));
+	return {
+		missing,
+		extra,
+		changed,
+		matched,
+		launchersAdded,
+		ok: missing.length === 0 && extra.length === 0 && changed.length === 0,
+	};
+};
+
+const compareEntry = (
+	before: ParityEntry,
+	after: ParityEntry,
+): ParityChange[] => {
+	const out: ParityChange[] = [];
+	const note = (field: string, b: unknown, a: unknown) =>
+		out.push({ id: before.id, field, before: b, after: a });
+
+	if (before.title !== after.title) note("title", before.title, after.title);
+	if (before.launch !== after.launch)
+		note("launch", before.launch, after.launch);
+	if (before.role !== after.role) note("role", before.role, after.role);
+	for (const k of ART_KINDS) {
+		// Only a LOST art kind is a regression. Gaining one is an improvement (the plugin can reach
+		// art the host never resolved), and failing a run over it would just train people to ignore
+		// the harness.
+		if (before.art[k] && !after.art[k]) note(`art.${k}`, true, false);
+	}
+	const keys = new Set([
+		...Object.keys(before.meta),
+		...Object.keys(after.meta),
+	]);
+	for (const k of keys) {
+		const b = before.meta[k];
+		const a = after.meta[k];
+		if (JSON.stringify(b) !== JSON.stringify(a)) note(`meta.${k}`, b, a);
+	}
+	return out;
+};
+
+/** Render a report for a terminal. Empty-ish when everything matched. */
+export const formatParityReport = (r: ParityReport): string => {
+	const lines: string[] = [];
+	lines.push(
+		r.ok
+			? `parity OK — ${r.matched} entries identical`
+			: `parity FAILED — ${r.matched} identical, ${r.missing.length} missing, ${r.extra.length} unexpected, ${r.changed.length} changed`,
+	);
+	for (const e of r.missing) lines.push(`  missing:  ${e.id}  ${e.title}`);
+	for (const e of r.extra) lines.push(`  extra:    ${e.id}  ${e.title}`);
+	for (const c of r.changed) {
+		lines.push(
+			`  changed:  ${c.id}  ${c.field}: ${JSON.stringify(c.before)} -> ${JSON.stringify(c.after)}`,
+		);
+	}
+	if (r.launchersAdded.length > 0) {
+		lines.push(
+			`  (+${r.launchersAdded.length} launcher ${r.launchersAdded.length === 1 ? "entry" : "entries"}, expected: ${r.launchersAdded
+				.map((e) => e.id)
+				.join(", ")})`,
+		);
+	}
+	// Art REPRESENTATION always changes on extraction (a host-relative proxy path or an inlined
+	// `data:` URL becomes a `file://` path or a CDN URL). Presence is what this harness checks, so
+	// say plainly that the bytes still want a human's eyes once.
+	if (r.ok) {
+		lines.push(
+			"  note: art is compared by presence, not value — spot-check a few covers render.",
+		);
+	}
+	return lines.join("\n");
+};

plugin-kit/src/library/parsers/art.ts

@@ -0,0 +1,120 @@
+// Where a title's cover art lives: Steam's local caches, its per-account `grid/` overrides, and the
+// public CDN. Ported from the host scanner's art resolution (steam.rs).
+//
+// After extraction a plugin emits art VALUES and the host serves them: a `file://` URL for anything
+// on disk (the documented local-art contract — the host proxies the bytes), or an absolute CDN URL
+// the client fetches itself. `data:` URLs remain legal but are small-logo-only: inlining covers is
+// what blew the host's 2 MB body limit at 49 titles during the playnite work.
+import * as path from "node:path";
+import { isFile, listDir } from "./fs.js";
+
+/** The four art slots the library model carries. */
+export type ArtKind = "portrait" | "hero" | "logo" | "header";
+
+export const ART_KINDS: readonly ArtKind[] = [
+	"portrait",
+	"hero",
+	"logo",
+	"header",
+];
+
+/** A `file://` URL for a local path — the shape the host's art proxy understands. */
+export const fileUrl = (p: string): string => {
+	// Percent-encode, but keep the separators: the host converts this back to a path and expects the
+	// structure intact. Windows drive paths become `file:///C:/…`.
+	const abs = path.resolve(p);
+	const posix = abs.replace(/\\/g, "/");
+	const encoded = posix
+		.split("/")
+		.map((seg) => encodeURIComponent(seg))
+		.join("/");
+	return posix.startsWith("/") ? `file://${encoded}` : `file:///${encoded}`;
+};
+
+/**
+ * The legacy flat CDN URL for a Steam appid's art kind. Correct for the many titles Valve hasn't
+ * re-hashed; newer ones serve from an unpredictable per-asset-hash path, where this 404s and the
+ * client falls through to its next candidate. That degradation is intentional and pre-existing.
+ */
+export const steamCdnUrl = (appid: number, kind: ArtKind): string | undefined => {
+	// A non-Steam shortcut's appid has the high bit set and is never a real store appid — the CDN
+	// would only 404, so don't emit a URL that is guaranteed to fail.
+	if ((appid & 0x8000_0000) !== 0) return undefined;
+	const file =
+		kind === "portrait"
+			? "library_600x900.jpg"
+			: kind === "hero"
+				? "library_hero.jpg"
+				: kind === "logo"
+					? "logo.png"
+					: "header.jpg";
+	return `https://cdn.cloudflare.steamstatic.com/steam/apps/${appid}/${file}`;
+};
+
+/** Filenames Steam's local `librarycache` uses per kind, in preference order (2x is sharper). */
+const localFilenames = (kind: ArtKind): string[] =>
+	kind === "portrait"
+		? ["library_600x900_2x.jpg", "library_600x900.jpg"]
+		: kind === "hero"
+			? ["library_hero.jpg"]
+			: kind === "logo"
+				? ["logo.png"]
+				: // Steam's local cache names the header asset differently from the store CDN's
+					// `header.jpg` — this trips everyone once.
+					["library_header.jpg"];
+
+/**
+ * This kind's file under one Steam root's `appcache/librarycache/<appid>/<hash>/`, or `undefined`.
+ * Steam reuses one hash dir per asset version, so there is normally exactly one candidate.
+ */
+export const findLocalArtFile = (
+	root: string,
+	appid: number,
+	kind: ArtKind,
+): string | undefined => {
+	const base = path.join(root, "appcache", "librarycache", String(appid));
+	for (const hash of listDir(base)) {
+		for (const name of localFilenames(kind)) {
+			const p = path.join(base, hash, name);
+			if (isFile(p)) return p;
+		}
+	}
+	// Older Steam wrote the files directly under `librarycache/` with the appid in the name.
+	for (const name of localFilenames(kind)) {
+		const flat = path.join(root, "appcache", "librarycache", `${appid}_${name}`);
+		if (isFile(flat)) return flat;
+	}
+	return undefined;
+};
+
+/**
+ * The `grid/` basenames Steam names each art kind under for an appid: portrait `<A>p`, hero
+ * `<A>_hero`, logo `<A>_logo`, wide capsule `<A>` — each as `.png` then `.jpg`.
+ *
+ * These overrides are the **only** art a non-Steam shortcut ever has.
+ */
+export const gridFilenames = (appid: number, kind: ArtKind): string[] => {
+	const base =
+		kind === "portrait"
+			? `${appid}p`
+			: kind === "hero"
+				? `${appid}_hero`
+				: kind === "logo"
+					? `${appid}_logo`
+					: `${appid}`;
+	return [`${base}.png`, `${base}.jpg`];
+};
+
+/** This kind's user override under a `userdata/<id>/config/grid/` dir, or `undefined`. */
+export const findGridArtFile = (
+	configDir: string,
+	appid: number,
+	kind: ArtKind,
+): string | undefined => {
+	const grid = path.join(configDir, "grid");
+	for (const name of gridFilenames(appid, kind)) {
+		const p = path.join(grid, name);
+		if (isFile(p)) return p;
+	}
+	return undefined;
+};

plugin-kit/src/library/parsers/fs.ts

@@ -0,0 +1,112 @@
+// Bounded filesystem reads and path confinement — the posture the in-host scanners established,
+// ported so a library plugin inherits it instead of re-deriving it.
+//
+// The rules here exist because a plugin reads files it does not own: a launcher's manifests, a
+// catalog cache, a `goggame-*.info` a user could have edited. None of that is hostile in the normal
+// case, and all of it is untrusted in the case that matters.
+import * as fs from "node:fs";
+import * as path from "node:path";
+
+/** A launcher manifest / `.acf` / `.info`: text, small. Matches `epic.rs`'s posture. */
+export const MAX_MANIFEST_BYTES = 1024 * 1024;
+/** A binary catalog cache (Epic's `catcache.bin`, a `shortcuts.vdf`): larger, still bounded. */
+export const MAX_CACHE_BYTES = 32 * 1024 * 1024;
+
+/**
+ * Read a file as UTF-8, refusing anything over `max`. `undefined` on any error, a non-regular file,
+ * or an over-cap file — a plugin scanning a directory must never die on one odd entry.
+ *
+ * The size is checked by `stat` BEFORE the read, so an enormous file costs a stat, not the memory.
+ */
+export const readTextCapped = (
+	file: string,
+	max = MAX_MANIFEST_BYTES,
+): string | undefined => {
+	try {
+		const st = fs.statSync(file);
+		if (!st.isFile() || st.size === 0 || st.size > max) return undefined;
+		return fs.readFileSync(file, "utf8");
+	} catch {
+		return undefined;
+	}
+};
+
+/** Read a file as bytes, refusing anything over `max`. Same posture as {@link readTextCapped}. */
+export const readBytesCapped = (
+	file: string,
+	max = MAX_CACHE_BYTES,
+): Uint8Array | undefined => {
+	try {
+		const st = fs.statSync(file);
+		if (!st.isFile() || st.size === 0 || st.size > max) return undefined;
+		return new Uint8Array(fs.readFileSync(file));
+	} catch {
+		return undefined;
+	}
+};
+
+/** Read + `JSON.parse` a capped text file. `undefined` on any read or parse failure. */
+export const readJsonCapped = <T = unknown>(
+	file: string,
+	max = MAX_MANIFEST_BYTES,
+): T | undefined => {
+	const text = readTextCapped(file, max);
+	if (text === undefined) return undefined;
+	try {
+		return JSON.parse(text) as T;
+	} catch {
+		return undefined;
+	}
+};
+
+/** List a directory's entry names, or `[]` if it isn't readable. */
+export const listDir = (dir: string): string[] => {
+	try {
+		return fs.readdirSync(dir);
+	} catch {
+		return [];
+	}
+};
+
+/** Does this path exist as a directory? */
+export const isDir = (p: string): boolean => {
+	try {
+		return fs.statSync(p).isDirectory();
+	} catch {
+		return false;
+	}
+};
+
+/** Does this path exist as a regular, non-empty file? */
+export const isFile = (p: string): boolean => {
+	try {
+		const st = fs.statSync(p);
+		return st.isFile() && st.size > 0;
+	} catch {
+		return false;
+	}
+};
+
+/**
+ * Join `rel` onto `base` **only if it cannot escape** — the port of the host's `confined_join`
+ * (gog.rs), which exists because a crafted `goggame-<id>.info` could otherwise point a play task's
+ * exe at an arbitrary program (security-review 2026-07-17).
+ *
+ * Refuses any relative path carrying a drive prefix (`C:`), a root (`/` or `\`), or a `..`
+ * component — each of which `path.join` would let REPLACE or climb out of `base`. `undefined` ⇒
+ * out of bounds, and the caller must refuse the launch rather than fall back to something plausible.
+ */
+export const confinedJoin = (base: string, rel: string): string | undefined => {
+	if (rel === "") return undefined;
+	// Normalize separators so a Windows-shaped relative path is checked on any platform (a plugin
+	// may parse a Windows manifest while its tests run on Linux).
+	const parts = rel.split(/[\\/]/);
+	if (parts[0] === "" ) return undefined; // rooted
+	if (/^[A-Za-z]:$/.test(parts[0])) return undefined; // drive prefix
+	if (parts.some((p) => p === "..")) return undefined; // traversal
+	const joined = path.join(base, ...parts.filter((p) => p !== "" && p !== "."));
+	// Belt and braces: the component check above is the real guard, but a symlink-free string check
+	// costs nothing and catches anything the split missed.
+	const rootWithSep = base.endsWith(path.sep) ? base : base + path.sep;
+	return joined === base || joined.startsWith(rootWithSep) ? joined : undefined;
+};

plugin-kit/src/library/parsers/http.ts

@@ -0,0 +1,94 @@
+// The one outbound-HTTP helper a library plugin should use, carrying the host's `fetch_image`
+// posture verbatim (art.rs): http(s) only, **no redirects**, a size cap, and a short timeout.
+//
+// The no-redirect rule is the important one and it is not paranoia: a scanner fetches URLs it read
+// out of a launcher's cache — data the plugin did not author. A `3xx` chased automatically is an
+// SSRF pivot from a process running on the operator's box (`http://169.254.169.254/…`, an internal
+// service). The host learned this in the 2026-07-17 security review; a plugin fetching the same
+// class of URL inherits the same rule. A rare legitimately-redirecting CDN just yields no art.
+import { HostRequestError } from "../../errors.js";
+import { Effect } from "effect";
+
+export interface FetchLimits {
+	/** Hard cap on the response body. Default 8 MiB — a cover never approaches it. */
+	readonly maxBytes?: number;
+	/** Wall-clock timeout in ms. Default 10 000. */
+	readonly timeoutMs?: number;
+}
+
+const DEFAULT_MAX = 8 * 1024 * 1024;
+const DEFAULT_TIMEOUT = 10_000;
+
+export interface FetchedBytes {
+	readonly bytes: Uint8Array;
+	readonly contentType: string;
+}
+
+/**
+ * GET an `http(s)` URL under the posture above. Fails with {@link HostRequestError} on any non-2xx,
+ * a redirect, an over-cap body, a timeout, or a non-http(s) scheme.
+ *
+ * Most scanners never need this: they emit CDN URLs and let the CLIENT fetch them, which is both
+ * faster and keeps the host out of the loop. Reach for it only when a store's art requires an API
+ * lookup the client cannot do (GOG's product API, Microsoft's display catalog).
+ */
+export const fetchBytes = (
+	url: string,
+	limits: FetchLimits = {},
+): Effect.Effect<FetchedBytes, HostRequestError> =>
+	Effect.tryPromise({
+		try: async (): Promise<FetchedBytes> => {
+			if (!/^https?:\/\//i.test(url)) {
+				throw new Error("only http(s) URLs may be fetched");
+			}
+			const maxBytes = limits.maxBytes ?? DEFAULT_MAX;
+			const signal = AbortSignal.timeout(limits.timeoutMs ?? DEFAULT_TIMEOUT);
+			// `redirect: "manual"` rather than "error": we want to SEE the 3xx and report it as a
+			// refusal, not have fetch throw something opaque.
+			const res = await fetch(url, { redirect: "manual", signal });
+			if (res.status >= 300 && res.status < 400) {
+				throw new Error(`refusing to follow a ${res.status} redirect`);
+			}
+			if (!res.ok) throw new Error(`HTTP ${res.status}`);
+			// Trust Content-Length when it is there (cheap rejection), but still bound the read: a
+			// hostile server can lie about it or omit it entirely.
+			const declared = Number(res.headers.get("content-length"));
+			if (Number.isFinite(declared) && declared > maxBytes) {
+				throw new Error(`body larger than ${maxBytes} bytes`);
+			}
+			const buf = new Uint8Array(await res.arrayBuffer());
+			if (buf.byteLength === 0) throw new Error("empty body");
+			if (buf.byteLength > maxBytes) {
+				throw new Error(`body larger than ${maxBytes} bytes`);
+			}
+			return {
+				bytes: buf,
+				contentType: res.headers.get("content-type") ?? "image/jpeg",
+			};
+		},
+		catch: (cause) =>
+			new HostRequestError({
+				method: "GET",
+				path: url,
+				cause,
+			}),
+	});
+
+/** {@link fetchBytes}, JSON-decoded. Same posture; use for a store's public product API. */
+export const fetchJson = <T = unknown>(
+	url: string,
+	limits: FetchLimits = {},
+): Effect.Effect<T, HostRequestError> =>
+	fetchBytes(url, limits).pipe(
+		Effect.flatMap((r) =>
+			Effect.try({
+				try: () => JSON.parse(new TextDecoder().decode(r.bytes)) as T,
+				catch: (cause) =>
+					new HostRequestError({
+						method: "GET",
+						path: url,
+						cause,
+					}),
+			}),
+		),
+	);

plugin-kit/src/library/parsers/index.ts

@@ -0,0 +1,61 @@
+// The launcher-file parsing toolkit: what the six in-host scanners hand-rolled, hoisted so a
+// library plugin is its scan function and nothing else.
+//
+// Everything here is total — a missing launcher, a truncated file, a schema drift in a launcher
+// upgrade all degrade to "no titles from this source", never to a thrown error. A scanner that dies
+// on one odd file takes the user's whole library with it.
+export {
+	ART_KINDS,
+	type ArtKind,
+	fileUrl,
+	findGridArtFile,
+	findLocalArtFile,
+	gridFilenames,
+	steamCdnUrl,
+} from "./art.js";
+export {
+	confinedJoin,
+	isDir,
+	isFile,
+	listDir,
+	MAX_CACHE_BYTES,
+	MAX_MANIFEST_BYTES,
+	readBytesCapped,
+	readJsonCapped,
+	readTextCapped,
+} from "./fs.js";
+export {
+	type FetchedBytes,
+	type FetchLimits,
+	fetchBytes,
+	fetchJson,
+} from "./http.js";
+export {
+	parseRegQuery,
+	regQueryValue,
+	regQueryValues,
+	regSubKeys,
+	type RegValue,
+	validRegKey,
+} from "./registry.js";
+export { openReadOnly, type ReadOnlyDb, withReadOnlyDb } from "./sqlite.js";
+export {
+	crc32,
+	parseShortcuts,
+	type Shortcut,
+	shortcutAppId,
+	shortcutGameId,
+} from "./shortcuts.js";
+export {
+	steamLibraryDirs,
+	steamRoots,
+	steamUserConfigDirs,
+} from "./steam-root.js";
+export {
+	type AppManifest,
+	isSteamTool,
+	parseAppManifest,
+	vdfField,
+	vdfPaths,
+	vdfValue,
+} from "./vdf.js";

plugin-kit/src/library/parsers/registry.ts

@@ -0,0 +1,94 @@
+// Windows registry reads by spawning `reg.exe query` — dependency-free, and (the part that
+// matters) it works from the scripting runner's LocalService account.
+//
+// **HKLM only, by design.** The runner runs as `NT AUTHORITY\LocalService` on Windows, which has no
+// user profile: HKCU is not the operator's hive there, it is LocalService's own — so a plugin that
+// read HKCU would silently see an empty registry rather than the user's launcher config. Every
+// launcher fact a scanner needs (Steam's InstallPath, GOG's game list) lives under HKLM
+// `WOW6432Node` anyway. Asking for HKCU is a bug, so this refuses it outright.
+import { spawnSync } from "node:child_process";
+
+/** One `reg.exe query` value row. */
+export interface RegValue {
+	readonly name: string;
+	/** `REG_SZ`, `REG_DWORD`, … */
+	readonly type: string;
+	readonly data: string;
+}
+
+const HKLM = "HKLM\\";
+
+/** Is this a key path this module will touch? See the module docs on why HKLM only. */
+export const validRegKey = (key: string): boolean =>
+	key.startsWith(HKLM) &&
+	key.length > HKLM.length &&
+	key.length <= 260 &&
+	!key.includes("..") &&
+	// `reg.exe` takes the key as one argv element (no shell), but keep the charset tame anyway so a
+	// malformed key can never turn into a switch.
+	!key.startsWith("/") &&
+	!/[\r\n\0"]/.test(key);
+
+const run = (args: string[]): string | undefined => {
+	if (process.platform !== "win32") return undefined;
+	const r = spawnSync("reg.exe", args, {
+		encoding: "utf8",
+		windowsHide: true,
+		// A registry read is instant; a hang means something is badly wrong and a scan must not
+		// block on it forever.
+		timeout: 10_000,
+		maxBuffer: 4 * 1024 * 1024,
+	});
+	if (r.status !== 0 || typeof r.stdout !== "string") return undefined;
+	return r.stdout;
+};
+
+/**
+ * The values directly under one HKLM key. `[]` when the key is absent, unreadable, or this is not
+ * Windows — a missing launcher is the normal case, never an error.
+ */
+export const regQueryValues = (key: string): RegValue[] => {
+	if (!validRegKey(key)) return [];
+	const out = run(["query", key]);
+	if (out === undefined) return [];
+	return parseRegQuery(out);
+};
+
+/** One named value under an HKLM key, or `undefined`. */
+export const regQueryValue = (key: string, name: string): string | undefined =>
+	regQueryValues(key).find((v) => v.name.toLowerCase() === name.toLowerCase())
+		?.data;
+
+/** The immediate SUBKEY paths under one HKLM key (GOG lists one subkey per installed game). */
+export const regSubKeys = (key: string): string[] => {
+	if (!validRegKey(key)) return [];
+	const out = run(["query", key]);
+	if (out === undefined) return [];
+	const prefix = `${key.toLowerCase()}\\`;
+	return out
+		.split(/\r?\n/)
+		.map((l) => l.trim())
+		.filter((l) => l.toLowerCase().startsWith(prefix))
+		.filter((l) => !l.slice(key.length + 1).includes("\\"));
+};
+
+/**
+ * Parse `reg.exe query` output rows: `    <name>    <TYPE>    <data>`, separated by runs of
+ * whitespace. Data may itself contain spaces (a path), so only the first two columns are split off.
+ *
+ * Exported for tests — the format is stable but this is exactly the kind of thing that quietly
+ * breaks, and a plugin's tests can pin it without a Windows box.
+ */
+export const parseRegQuery = (stdout: string): RegValue[] => {
+	const out: RegValue[] = [];
+	for (const raw of stdout.split(/\r?\n/)) {
+		// Value rows are indented; the key path header is not.
+		if (!/^\s/.test(raw)) continue;
+		const line = raw.trim();
+		if (line === "") continue;
+		const m = line.match(/^(.*?)\s{2,}(REG_[A-Z_]+)\s{2,}([\s\S]*)$/);
+		if (!m) continue;
+		out.push({ name: m[1], type: m[2], data: m[3] });
+	}
+	return out;
+};

plugin-kit/src/library/parsers/shortcuts.ts

@@ -0,0 +1,160 @@
+// Steam's BINARY `shortcuts.vdf` — the user's "Add a Non-Steam Game to My Library" entries.
+//
+// Ported from the host's in-tree scanner (crates/punktfunk-host/src/library/steam.rs), together
+// with its unit tests, which are the real specification here: the format is undocumented, and the
+// two id derivations below (`shortcutAppId`, `shortcutGameId`) are the difference between a
+// shortcut that launches and one that silently does nothing.
+//
+// Format: a 1-byte type tag (`0x00` nested map, `0x01` string, `0x02` int32, `0x07` uint64), a
+// NUL-terminated key, then a type-specific payload; `0x08` closes the current map. The whole file is
+// one `shortcuts` map whose children (keyed "0", "1", …) are the individual shortcuts.
+//
+// Lenient and total by design: a truncated file or an unrecognized tag stops the walk and returns
+// whatever parsed so far. A user's shortcuts file is not something to be strict about.
+
+export interface Shortcut {
+	/** The 32-bit shortcut appid — always high-bit set. Keys the entry id and its `grid/` art. */
+	readonly appid: number;
+	readonly name: string;
+	/** The shortcut's target, as Steam stores it (quoted, possibly with trailing arguments). */
+	readonly exe: string;
+	readonly hidden: boolean;
+}
+
+/** A cursor over the buffer — the ported code's `pos` threaded explicitly. */
+interface Cursor {
+	pos: number;
+}
+
+/** Read a NUL-terminated UTF-8 string, advancing past the terminator. `undefined` if unterminated. */
+const readCStr = (buf: Uint8Array, c: Cursor): string | undefined => {
+	const start = c.pos;
+	let end = start;
+	while (end < buf.length && buf[end] !== 0) end++;
+	if (end >= buf.length) return undefined;
+	const s = new TextDecoder("utf-8").decode(buf.subarray(start, end));
+	c.pos = end + 1;
+	return s;
+};
+
+/** Read a little-endian int32, advancing 4 bytes. `undefined` if fewer than 4 remain. */
+const readI32 = (buf: Uint8Array, c: Cursor): number | undefined => {
+	if (c.pos + 4 > buf.length) return undefined;
+	const v = new DataView(buf.buffer, buf.byteOffset + c.pos, 4).getInt32(0, true);
+	c.pos += 4;
+	return v;
+};
+
+/** Skip a nested map's contents (positioned just after its key) up to and including its `0x08`. */
+const skipMap = (buf: Uint8Array, c: Cursor): boolean => {
+	for (;;) {
+		if (c.pos >= buf.length) return false;
+		const tag = buf[c.pos];
+		c.pos += 1;
+		if (tag === 0x08) return true;
+		if (readCStr(buf, c) === undefined) return false;
+		if (tag === 0x00) {
+			if (!skipMap(buf, c)) return false;
+		} else if (tag === 0x01) {
+			if (readCStr(buf, c) === undefined) return false;
+		} else if (tag === 0x02) {
+			c.pos += 4;
+		} else if (tag === 0x07) {
+			c.pos += 8;
+		} else {
+			return false;
+		}
+	}
+};
+
+/** Parse one shortcut's fields (positioned just after its index key) up to the map-closing `0x08`. */
+const parseOne = (buf: Uint8Array, c: Cursor): Shortcut | undefined => {
+	let appid: number | undefined;
+	let name = "";
+	let exe = "";
+	let hidden = false;
+	for (;;) {
+		if (c.pos >= buf.length) return undefined;
+		const tag = buf[c.pos];
+		c.pos += 1;
+		if (tag === 0x08) break;
+		const key = readCStr(buf, c)?.toLowerCase();
+		if (key === undefined) return undefined;
+		if (tag === 0x00) {
+			if (!skipMap(buf, c)) return undefined; // nested map (e.g. `tags`) — not needed
+		} else if (tag === 0x01) {
+			const val = readCStr(buf, c);
+			if (val === undefined) return undefined;
+			if (key === "appname") name = val;
+			else if (key === "exe") exe = val;
+		} else if (tag === 0x02) {
+			const val = readI32(buf, c);
+			if (val === undefined) return undefined;
+			if (key === "appid") appid = val >>> 0;
+			else if (key === "ishidden") hidden = val !== 0;
+		} else if (tag === 0x07) {
+			c.pos += 8; // uint64 — skip
+		} else {
+			return undefined; // unknown tag: payload size unknown, can't continue safely
+		}
+	}
+	if (name.trim() === "") return undefined; // nothing worth showing
+	// Prefer the stored appid; fall back to Steam's derivation when it's absent (0 / missing).
+	const id = appid && appid !== 0 ? appid : shortcutAppId(exe, name);
+	return { appid: id, name, exe, hidden };
+};
+
+/** Parse a binary `shortcuts.vdf` into its shortcuts. Never throws. */
+export const parseShortcuts = (buf: Uint8Array): Shortcut[] => {
+	const out: Shortcut[] = [];
+	const c: Cursor = { pos: 0 };
+	// Enter the top-level map (`<0x00> "shortcuts" <NUL>`); tolerate any key name.
+	if (buf[0] !== 0x00) return out;
+	c.pos = 1;
+	if (readCStr(buf, c) === undefined) return out;
+	while (c.pos < buf.length) {
+		const tag = buf[c.pos];
+		c.pos += 1;
+		if (tag !== 0x00) break; // `0x08` (end of shortcuts) or anything unexpected
+		if (readCStr(buf, c) === undefined) break; // the index key ("0", "1", …)
+		const sc = parseOne(buf, c);
+		if (!sc) break;
+		out.push(sc);
+	}
+	return out;
+};
+
+/** Standard reflected (IEEE) CRC-32 — what Steam hashes a shortcut's `exe + name` with. */
+export const crc32 = (data: Uint8Array): number => {
+	let crc = 0xffff_ffff;
+	for (const byte of data) {
+		crc ^= byte;
+		for (let i = 0; i < 8; i++) {
+			const mask = -(crc & 1);
+			crc = (crc >>> 1) ^ (0xedb8_8320 & mask);
+		}
+	}
+	return (~crc) >>> 0;
+};
+
+/**
+ * The 32-bit appid Steam derives for a shortcut from its target+name — `crc32(exe + name)` with the
+ * high bit set. Only used when `shortcuts.vdf` omits the stored `appid` (very old Steam); modern
+ * Steam writes it and the stored value is preferred.
+ *
+ * The high bit is load-bearing downstream: it is how a shortcut is told apart from a real store
+ * appid, which is what makes the CDN art fetch skippable for shortcuts (they only ever have `grid/`
+ * overrides).
+ */
+export const shortcutAppId = (exe: string, name: string): number =>
+	(crc32(new TextEncoder().encode(exe + name)) | 0x8000_0000) >>> 0;
+
+/**
+ * The 64-bit game id `steam://rungameid/` needs in order to launch a non-Steam shortcut: high dword
+ * = the 32-bit shortcut appid, low dword = the shortcut marker `0x02000000`.
+ *
+ * Handing `rungameid` the bare 32-bit appid does NOT launch a shortcut — it must be this composed
+ * id. Returned as a decimal string because it exceeds 2^53 and would lose precision as a `number`.
+ */
+export const shortcutGameId = (appid: number): string =>
+	((BigInt(appid >>> 0) << 32n) | 0x0200_0000n).toString();

plugin-kit/src/library/parsers/sqlite.ts

@@ -0,0 +1,68 @@
+// Read-only SQLite over `bun:sqlite` — for launcher databases a plugin must never disturb.
+//
+// Lutris' `pga.db` is the motivating case: it belongs to a running application, and a scanner that
+// opened it read-write could take a write lock, create `-wal`/`-shm` sidecars next to it, or (worst
+// case) be blamed for a corrupted library. `immutable=1` promises the file will not change while
+// open, which makes Bun skip locking entirely — the strictest possible "look, don't touch".
+import { Database } from "bun:sqlite";
+import { isFile } from "./fs.js";
+
+export interface ReadOnlyDb {
+	/** Run a query and return its rows. Returns `[]` rather than throwing on a bad query. */
+	readonly query: <T = Record<string, unknown>>(
+		sql: string,
+		...params: unknown[]
+	) => T[];
+	readonly close: () => void;
+}
+
+/**
+ * Open a launcher database read-only and immutably. `undefined` if the file is absent or not a
+ * database — the normal "this launcher isn't installed" case, not an error.
+ *
+ * Always `close()` when done (or use {@link withReadOnlyDb}, which does it for you).
+ */
+export const openReadOnly = (file: string): ReadOnlyDb | undefined => {
+	if (!isFile(file)) return undefined;
+	let db: Database;
+	try {
+		// `readonly` alone still takes locks and can spawn WAL sidecars; `immutable=1` is what makes
+		// this a pure read. It is safe here precisely because a scan is a point-in-time snapshot —
+		// if the launcher writes mid-scan we simply pick it up on the next sync.
+		db = new Database(`file:${encodeURI(file)}?immutable=1`, { readonly: true });
+	} catch {
+		return undefined;
+	}
+	return {
+		query: <T = Record<string, unknown>>(sql: string, ...params: unknown[]) => {
+			try {
+				return db.query(sql).all(...(params as never[])) as T[];
+			} catch {
+				// A schema drift (a renamed column in a launcher upgrade) must degrade to "no
+				// titles from this source", never take the whole plugin down.
+				return [] as T[];
+			}
+		},
+		close: () => {
+			try {
+				db.close();
+			} catch {
+				/* already closed */
+			}
+		},
+	};
+};
+
+/** Open, use, and always close. Returns `undefined` when the database isn't there. */
+export const withReadOnlyDb = <T>(
+	file: string,
+	use: (db: ReadOnlyDb) => T,
+): T | undefined => {
+	const db = openReadOnly(file);
+	if (!db) return undefined;
+	try {
+		return use(db);
+	} finally {
+		db.close();
+	}
+};

plugin-kit/src/library/parsers/steam-root.ts

@@ -0,0 +1,104 @@
+// Where Steam lives on this host, and which `steamapps` dirs hold installed titles.
+//
+// Ported from the host scanner (steam.rs `steam_roots` / `steam_library_dirs`) with one deliberate
+// addition and one deliberate exclusion, both about the Windows runner's account:
+//
+//   * ADDED: HKLM `WOW6432Node\Valve\Steam\InstallPath`, so a non-default Steam install dir is
+//     found. The host scanner never covered this (it relied on an explorer.exe protocol fallback at
+//     launch time), but a plugin that can't find the root finds no games at all.
+//   * EXCLUDED: HKCU `Software\Valve\Steam`. The runner is LocalService, whose HKCU is its own empty
+//     hive, not the operator's — reading it would look like "Steam isn't installed".
+import * as os from "node:os";
+import * as path from "node:path";
+import { isDir, listDir, readTextCapped } from "./fs.js";
+import { regQueryValue } from "./registry.js";
+import { vdfPaths } from "./vdf.js";
+
+/** Canonicalize-ish: resolve and drop a trailing separator so dedup is reliable. */
+const norm = (p: string): string => path.resolve(p);
+
+/**
+ * Candidate Steam roots that actually exist (have a `steamapps` dir), deduped.
+ *
+ * A "root" is the Steam install itself — `userdata/`, `appcache/` and the first `steamapps/` live
+ * under it. Extra library folders on other drives are NOT roots; see {@link steamLibraryDirs}.
+ */
+export const steamRoots = (): string[] => {
+	const candidates: string[] = [];
+	if (process.platform === "win32") {
+		for (const v of ["ProgramFiles(x86)", "ProgramFiles", "ProgramW6432"]) {
+			const pf = process.env[v];
+			if (pf) candidates.push(path.join(pf, "Steam"));
+		}
+		// The registry install path — covers a Steam installed somewhere other than Program Files.
+		for (const key of [
+			"HKLM\\SOFTWARE\\WOW6432Node\\Valve\\Steam",
+			"HKLM\\SOFTWARE\\Valve\\Steam",
+		]) {
+			const p = regQueryValue(key, "InstallPath");
+			if (p) candidates.push(p);
+		}
+	} else {
+		const home = os.homedir();
+		if (home) {
+			candidates.push(
+				path.join(home, ".local/share/Steam"),
+				path.join(home, ".steam/steam"),
+				path.join(home, ".steam/root"),
+				// Flatpak Steam
+				path.join(home, ".var/app/com.valvesoftware.Steam/.local/share/Steam"),
+			);
+		}
+	}
+	const seen = new Set<string>();
+	const roots: string[] = [];
+	for (const c of candidates) {
+		const n = norm(c);
+		if (!seen.has(n) && isDir(path.join(n, "steamapps"))) {
+			seen.add(n);
+			roots.push(n);
+		}
+	}
+	return roots;
+};
+
+/**
+ * Every `steamapps` dir holding installed titles: each root's own, plus the extra library folders
+ * listed in its `libraryfolders.vdf` (Steam installs to other drives).
+ */
+export const steamLibraryDirs = (roots = steamRoots()): string[] => {
+	const seen = new Set<string>();
+	const dirs: string[] = [];
+	const push = (p: string) => {
+		const n = norm(p);
+		if (!seen.has(n) && isDir(n)) {
+			seen.add(n);
+			dirs.push(n);
+		}
+	};
+	for (const root of roots) {
+		const steamapps = path.join(root, "steamapps");
+		const text = readTextCapped(path.join(steamapps, "libraryfolders.vdf"));
+		if (text !== undefined) {
+			for (const p of vdfPaths(text)) push(path.join(p, "steamapps"));
+		}
+		push(steamapps);
+	}
+	return dirs;
+};
+
+/**
+ * Every `userdata/<accountId>/config` dir across all roots — one per Steam account that has signed
+ * in on this host. `shortcuts.vdf` and the `grid/` art overrides live here.
+ */
+export const steamUserConfigDirs = (roots = steamRoots()): string[] => {
+	const out: string[] = [];
+	for (const root of roots) {
+		const userdata = path.join(root, "userdata");
+		for (const acct of listDir(userdata)) {
+			const cfg = path.join(userdata, acct, "config");
+			if (isDir(cfg)) out.push(cfg);
+		}
+	}
+	return out;
+};

plugin-kit/src/library/parsers/vdf.ts

@@ -0,0 +1,80 @@
+// Valve Data Format (text) — the flat-field reader Steam's `libraryfolders.vdf` and
+// `appmanifest_<appid>.acf` need, ported from the host's in-tree scanner
+// (crates/punktfunk-host/src/library/steam.rs `vdf_value` / `vdf_paths` / `scan_manifests`).
+//
+// Deliberately NOT a full VDF parser. Every field these files expose that a library plugin cares
+// about sits on one line as `"key"  "value"`, and a real parser would be a much larger surface to
+// keep correct against a format Valve changes without notice. If you need nested values, read the
+// file yourself — this is the 90% case, kept small enough to be obviously right.
+
+/** `"<key>" "<value>"` on a single line → `<value>`. Whitespace between the two is arbitrary. */
+export const vdfValue = (line: string, key: string): string | undefined => {
+	const rest = line.trimStart();
+	const prefix = `"${key}"`;
+	if (!rest.startsWith(prefix)) return undefined;
+	const after = rest.slice(prefix.length);
+	const open = after.indexOf('"');
+	if (open === -1) return undefined;
+	const value = after.slice(open + 1);
+	const close = value.indexOf('"');
+	if (close === -1) return undefined;
+	return value.slice(0, close);
+};
+
+/** The first `"<key>" "<value>"` anywhere in a multi-line document. */
+export const vdfField = (text: string, key: string): string | undefined => {
+	for (const line of text.split("\n")) {
+		const v = vdfValue(line, key);
+		if (v !== undefined) return v;
+	}
+	return undefined;
+};
+
+/**
+ * Every `"path" "<dir>"` value in a `libraryfolders.vdf` — the extra drives Steam installs to.
+ *
+ * On Windows the values are backslash-escaped (`D:\\SteamLibrary`), so `\\` collapses to `\`. POSIX
+ * paths need no unescaping, and the collapse is harmless there (a literal `\\` in a Linux path is
+ * vanishingly rare and was already ambiguous).
+ */
+export const vdfPaths = (text: string): string[] =>
+	text
+		.split("\n")
+		.map((l) => vdfValue(l, "path"))
+		.filter((p): p is string => p !== undefined)
+		.map((p) => p.replaceAll("\\\\", "\\"));
+
+/** One installed title as described by its `appmanifest_<appid>.acf`. */
+export interface AppManifest {
+	readonly appid: number;
+	readonly name: string;
+	/** The bare folder name under this library's `common/` — resolve it yourself. */
+	readonly installdir?: string;
+}
+
+/** Parse an `.acf` manifest's flat fields. `undefined` when it carries no usable appid+name. */
+export const parseAppManifest = (text: string): AppManifest | undefined => {
+	const appid = Number(vdfField(text, "appid"));
+	const name = vdfField(text, "name");
+	if (!Number.isInteger(appid) || appid <= 0 || !name) return undefined;
+	const installdir = vdfField(text, "installdir");
+	return installdir ? { appid, name, installdir } : { appid, name };
+};
+
+/**
+ * Steam installs runtimes and redistributables as "apps" too. A *game* library must not list them.
+ * Ported verbatim from the host scanner so an extracted steam plugin filters identically — the
+ * parity harness compares entry sets, and a stray Proton row would fail it.
+ */
+export const isSteamTool = (appid: number, name: string): boolean => {
+	// Steamworks Common Redistributables; Steam Linux Runtime 1.0/2.0/3.0 (Sniper/Soldier).
+	const TOOL_IDS = [228980, 1070560, 1391110, 1628350, 1493710];
+	if (TOOL_IDS.includes(appid)) return true;
+	const n = name.toLowerCase();
+	return (
+		n.includes("proton") ||
+		n.startsWith("steam linux runtime") ||
+		n.includes("steamworks common") ||
+		n.includes("steamvr")
+	);
+};

plugin-kit/src/reconcile.ts

@@ -9,13 +9,36 @@ import type { ProviderEntry } from "./wire.js";
 
 export * from "./wire.js";
 
+/** What the host echoed back for one reconciled entry — enough to tell whether a claim took. */
+export interface ReconciledEntry {
+	readonly id: string;
+	readonly external_id?: string;
+	/** The store badge the host assigned: the claim when it honoured one, else `"custom"`. */
+	readonly store?: string;
+}
+
 export interface ProviderClientService {
-	/** Full-replace reconcile: PUT the desired set; the host diffs by `external_id`. */
+	/**
+	 * Full-replace reconcile: PUT the desired set; the host diffs by `external_id`.
+	 *
+	 * `store` claims that store for this provider (design D2), which is what makes the entries carry
+	 * the store's own identity — deterministic `<store>:<external_id>` ids instead of opaque
+	 * `custom:<id>` ones, the store's badge, and suppression of the host's matching built-in scanner
+	 * so the two never double-list. One provider per store: a second claimant gets a 409.
+	 *
+	 * Returns the host's echoed entries so a caller can verify the claim actually took — a host
+	 * predating claims ignores the query parameter silently, and the only way to notice is that the
+	 * entries come back as `custom`.
+	 */
 	readonly reconcile: (
 		providerId: string,
 		entries: ReadonlyArray<ProviderEntry>,
-	) => Effect.Effect<void, HostRequestError>;
-	/** Remove every entry this provider owns (the explicit-uninstall path). */
+		store?: string,
+	) => Effect.Effect<ReadonlyArray<ReconciledEntry>, HostRequestError>;
+	/**
+	 * Remove every entry this provider owns **and release its store claim** (the explicit-uninstall
+	 * path). Releasing is what brings the host's built-in scanner back.
+	 */
 	readonly remove: (providerId: string) => Effect.Effect<void, HostRequestError>;
 }
 
@@ -28,10 +51,25 @@ export class ProviderClient extends Context.Service<
 			Effect.gen(function* () {
 				const host = yield* HostClient;
 				return {
-					reconcile: (providerId, entries) =>
+					reconcile: (providerId, entries, store) =>
 						host
-							.request("PUT", `/library/provider/${providerId}`, entries)
-							.pipe(Effect.asVoid),
+							.request(
+								"PUT",
+								`/library/provider/${providerId}${
+									store ? `?store=${encodeURIComponent(store)}` : ""
+								}`,
+								entries,
+							)
+							.pipe(
+								// The host answers with its resulting entries. An older host may answer
+								// with something else, so treat a non-array as "no echo" rather than
+								// failing the sync.
+								Effect.map((body) =>
+									Array.isArray(body)
+										? (body as ReadonlyArray<ReconciledEntry>)
+										: [],
+								),
+							),
 					remove: (providerId) =>
 						host
 							.request("DELETE", `/library/provider/${providerId}`)

plugin-kit/src/ui-server.ts

@@ -3,8 +3,9 @@
 // register/renew/deregister through Scope. Validated end-to-end by the phase-0 spike:
 // core-only env layers, no platform package, SPA fallthrough preserved.
 import { type PluginUiHandle, servePluginUi } from "@punktfunk/host";
-import { Effect, FileSystem, Layer, Path, Scope } from "effect";
+import { Effect, FileSystem, Layer, Path, Schema, Scope } from "effect";
 import { Etag, HttpPlatform, HttpRouter } from "effect/unstable/http";
+import type { ConfigService } from "./config.js";
 import { UiServeError } from "./errors.js";
 import { HostClient, PluginInfo } from "./host-client.js";
 
@@ -17,6 +18,100 @@ export const httpApiEnv = Layer.provideMerge(
 	FileSystem.layerNoop({}),
 );
 
+/**
+ * Derive a JSON Schema for a config schema, for the console's generic settings form.
+ *
+ * Returns `null` when derivation isn't possible, which the console reads as "render the raw JSON
+ * editor instead" — the fallback that bounds this whole feature's risk.
+ *
+ * Authoring rules, verified against effect 4.0.0-beta.99 and pinned by
+ * `test/library-config.test.ts` — if an effect upgrade changes any of them, that test fails:
+ *
+ * * Use `Schema.Finite` / `Schema.Int`, **never `Schema.Number`** — Number's *encoded* form admits
+ *   the strings `"NaN"`/`"Infinity"`/`"-Infinity"`, so it derives a four-way `anyOf` that no sane
+ *   form can render as a number input.
+ * * A decoding default is an **Effect**: `withDecodingDefaultKey(Effect.succeed(true), …)`. Passing
+ *   a bare thunk (`() => true`) still derives a schema and still type-checks, then dies at DECODE
+ *   time with "Not a valid effect" — deriving is not evidence that the schema works.
+ * * Annotate every field: `.annotate({ title, description, default })`. The derivation does NOT
+ *   infer `default` from `withDecodingDefaultKey`, so an un-annotated field shows no placeholder.
+ * * A *checked* schema (`Schema.Int`, or anything with `.check(...)`) nests its annotations and
+ *   constraints under `allOf`, so a form must merge those branches, not read only the top level.
+ * * `Schema.Literals([...])` derives a clean `enum` — prefer it over a union of strings. A union of
+ *   non-literals derives an `anyOf`, which is the JSON-editor fallback case.
+ * * Fields carrying `withDecodingDefaultKey(..., { encodingStrategy: "omit" })` correctly drop out
+ *   of `required`, which is what keeps the raw file free of baked-in defaults.
+ */
+export const deriveConfigJsonSchema = (
+	schema: Schema.Top,
+): Record<string, unknown> | null => {
+	try {
+		const doc = Schema.toJsonSchemaDocument(schema as never);
+		return doc as unknown as Record<string, unknown>;
+	} catch {
+		// A schema shape the derivation can't express (a transform, a recursive ref). The console
+		// falls back to the JSON editor; the PUT still validates by decode, so nothing is lost but
+		// the pretty form.
+		return null;
+	}
+};
+
+/** The plugin config surface the console's settings drawer drives. */
+export interface ServeUiConfig<S extends Schema.Top> {
+	/** The schema the raw file is validated against, and the form is derived from. */
+	readonly schema: S;
+	/** The config service (from `makeConfigService`) holding the raw round-trip semantics. */
+	readonly service: ConfigService<S>;
+}
+
+/**
+ * The `/__config` request handler, split out so it can be driven directly in tests (the wire shape
+ * is the contract the console's settings drawer codes against — it deserves a real round-trip test,
+ * not a mock).
+ *
+ * `ConfigService`'s effects are context-free by construction (the `PluginInfo` was resolved when the
+ * service was built), so this runs them straight from a plain async handler.
+ */
+export const makeConfigHandler = <S extends Schema.Top>(
+	cfg: ServeUiConfig<S>,
+): ((req: Request) => Promise<Response>) => {
+	// The derivation is stable for the life of the process — do it once, not per request.
+	const schema = deriveConfigJsonSchema(cfg.schema);
+	return async (req: Request): Promise<Response> => {
+		if (req.method === "GET") {
+			// A config file that fails to decode must not blank the whole drawer — answer with a
+			// null value so the operator can still see (and replace) what is on disk.
+			const value = await Effect.runPromise(cfg.service.loadRaw).catch(
+				() => null,
+			);
+			return Response.json({ schema, value });
+		}
+		if (req.method === "PUT") {
+			let body: unknown;
+			try {
+				body = await req.json();
+			} catch (cause) {
+				return Response.json(
+					{ error: "body must be JSON", issue: String(cause) },
+					{ status: 400 },
+				);
+			}
+			try {
+				// Validate-by-decode, persist RAW: `saveRaw` refuses a body the schema rejects and
+				// never writes decoded defaults back into the operator's file.
+				await Effect.runPromise(cfg.service.saveRaw(body));
+				return Response.json({ ok: true });
+			} catch (cause) {
+				return Response.json(
+					{ error: "config rejected", issue: String(cause) },
+					{ status: 400 },
+				);
+			}
+		}
+		return new Response("method not allowed", { status: 405 });
+	};
+};
+
 export interface ServeUiOptions {
 	/** Console nav title. */
 	readonly title: string;
@@ -26,12 +121,33 @@ export interface ServeUiOptions {
 	readonly version?: string;
 	/** Built SPA directory (served with SPA fallback by the SDK). */
 	readonly staticDir?: string | URL;
+	/**
+	 * What kind of plugin this is (`[a-z][a-z0-9-]{0,31}`). `"library"` keeps the plugin out of the
+	 * console nav — its entry point is the Library section's Game sources surface instead.
+	 */
+	readonly category?: string;
+	/**
+	 * Serve `GET`/`PUT /__config` for the console's **generic settings form**, so a plugin with
+	 * settings does not need to ship an SPA at all.
+	 *
+	 * `GET` answers `{schema, value}` — the derived JSON Schema (or `null`) and the raw,
+	 * operator-authored config. `PUT` validates by decoding the body against the schema and, only
+	 * then, persists it **raw**; defaults are never baked into the file. A rejected body comes back
+	 * 400 with the decode issue.
+	 *
+	 * Auth is the existing per-boot UI secret — the console reaches this through its session-gated
+	 * `/plugin-ui/<id>/…` proxy, so there is no new host surface and nothing new exposed to the LAN.
+	 */
+	readonly config?: ServeUiConfig<Schema.Top>;
 	/**
 	 * The plugin API: `HttpApiBuilder.layer(api)` + group handler layers + raw routes
 	 * (e.g. `sseRoute`), with plugin services already provided. `httpApiEnv` is provided
 	 * here — only `HttpRouter` may remain open.
+	 *
+	 * Optional: a plugin whose only surface is `__config` (every library scanner) serves no API of
+	 * its own, and omitting this leaves an empty router that 404s under `apiPrefix`.
 	 */
-	readonly api: Layer.Layer<never, never, HttpRouter.HttpRouter>;
+	readonly api?: Layer.Layer<never, never, HttpRouter.HttpRouter>;
 	/** Path prefix owned by the API handler (default "/api/"). */
 	readonly apiPrefix?: string;
 }
@@ -54,14 +170,22 @@ export const serveUi = (
 		const prefix = opts.apiPrefix ?? "/api/";
 
 		const { handler, dispose } = HttpRouter.toWebHandler(
-			Layer.provide(opts.api, httpApiEnv),
+			Layer.provide(opts.api ?? Layer.empty, httpApiEnv),
 		);
 		yield* Effect.addFinalizer(() =>
 			Effect.promise(() => dispose()).pipe(Effect.ignore),
 		);
 
+		const serveConfig = opts.config ? makeConfigHandler(opts.config) : undefined;
+
 		const fetch = async (req: Request): Promise<Response | undefined> => {
 			const url = new URL(req.url);
+			// `__`-prefixed paths are the kit/SDK's own contract surface (`__health` lives in the
+			// SDK), deliberately checked BEFORE the API prefix and before any static asset so a
+			// plugin's own routes can never shadow them.
+			if (url.pathname === "/__config") {
+				return serveConfig?.(req) ?? new Response("not found", { status: 404 });
+			}
 			if (!url.pathname.startsWith(prefix)) return undefined; // → static SPA
 			return handler(req);
 		};
@@ -79,6 +203,9 @@ export const serveUi = (
 						...(opts.staticDir !== undefined
 							? { staticDir: opts.staticDir }
 							: {}),
+						...(opts.category !== undefined
+							? { category: opts.category }
+							: {}),
 						fetch,
 					}),
 				catch: (cause) => new UiServeError({ cause }),

plugin-kit/src/wire.ts

@@ -12,12 +12,45 @@ export const Artwork = Schema.Struct({
 });
 export type Artwork = typeof Artwork.Type;
 
+/**
+ * How the host should launch a title. **The host owns this vocabulary** — it validates the value
+ * per kind and builds the actual URI / command line itself, so a plugin only ever supplies a
+ * validated value, never a command. That is the security invariant behind the whole provider lane:
+ * a client sends an entry id, and the host resolves what to run.
+ *
+ * `kind` is a plain string rather than a union so the kit never has to ship a release to keep up
+ * with a host that grew a new kind. The kinds the host understands today:
+ *
+ * | kind | value | platforms |
+ * |---|---|---|
+ * | `command` | a shell command (operator-trust tier) | both |
+ * | `steam_appid` | digits — an appid, or a 64-bit non-Steam-shortcut game id | both |
+ * | `steam_ui` | `bigpicture` \| `desktop` — opens the Steam client itself | both |
+ * | `launcher_ui` | a store id (`heroic`, `lutris`) — opens that launcher's own UI | linux |
+ * | `lutris_id` | digits — a pga.db game id | linux |
+ * | `heroic` | `<runner>:<appName>`, runner ∈ legendary/gog/nile | linux |
+ * | `epic` | `<namespace>:<catalogItemId>:<appName>` or a bare appName | windows |
+ * | `gog` | `exe \t args \t workdir` | windows |
+ * | `aumid` | `<PFN>!<AppId>` | windows |
+ *
+ * An unknown kind is accepted on the wire and simply yields no launch recipe on that host, so a
+ * plugin targeting a newer host degrades to an unlaunchable tile rather than a failed reconcile.
+ */
 export const LaunchSpec = Schema.Struct({
-	kind: Schema.Literal("command"),
+	kind: Schema.String,
 	value: Schema.String,
 });
 export type LaunchSpec = typeof LaunchSpec.Type;
 
+/**
+ * Whether an entry is an ordinary title or the launcher application itself (Steam Big Picture,
+ * Heroic, Playnite fullscreen). Launcher entries launch, lease and list exactly like games; a
+ * console or client that knows the field groups them into their own rail, and one that doesn't
+ * renders them as plain tiles.
+ */
+export const GameRole = Schema.Literals(["game", "launcher"]);
+export type GameRole = typeof GameRole.Type;
+
 export const PrepStep = Schema.Struct({
 	do: Schema.String,
 	undo: Schema.optionalKey(Schema.NullOr(Schema.String)),
@@ -43,6 +76,28 @@ export const DetectHint = Schema.Struct({
 	exe: Schema.optionalKey(Schema.NullOr(Schema.String)),
 	/** The executable's file name (`Hades.exe`), when its location isn't fixed. Weakest signal. */
 	process_name: Schema.optionalKey(Schema.NullOr(Schema.String)),
+	/**
+	 * The Steam appid, for a title Steam itself installed. On Linux this is the **sharpest** signal
+	 * there is: Steam wraps every launch — native or Proton — in `reaper SteamLaunch AppId=<appid>`,
+	 * whose lifetime is exactly the game's. Send it if you have it.
+	 */
+	steam_appid: Schema.optionalKey(Schema.NullOr(Schema.Number)),
+	/**
+	 * An environment variable the launcher stamps on the game's process. Load-bearing for launchers
+	 * that run games under Proton/Wine, where the process tree tells you very little (Heroic's
+	 * `HEROIC_APP_NAME` is the verified case). Omit `value` to match on the key's mere presence —
+	 * only safe for a launcher that runs one game at a time.
+	 */
+	env_marker: Schema.optionalKey(
+		Schema.NullOr(
+			Schema.Struct({
+				/** `[A-Za-z0-9_]{1,64}` — the host rejects anything else. */
+				key: Schema.String,
+				/** At most 256 chars. */
+				value: Schema.optionalKey(Schema.NullOr(Schema.String)),
+			}),
+		),
+	),
 });
 export type DetectHint = typeof DetectHint.Type;
 
@@ -76,6 +131,8 @@ export const ProviderEntry = Schema.Struct({
 	launch: Schema.optionalKey(Schema.NullOr(LaunchSpec)),
 	prep: Schema.optionalKey(Schema.Array(PrepStep)),
 	detect: Schema.optionalKey(DetectHint),
+	/** `"game"` (default) or `"launcher"` — see {@link GameRole}. */
+	role: Schema.optionalKey(GameRole),
 	...GameMeta.fields,
 });
 export type ProviderEntry = typeof ProviderEntry.Type;

plugin-kit/test/library-config.test.ts

@@ -0,0 +1,240 @@
+// The `__config` contract — the wire shape the console's generic settings drawer codes against,
+// plus the JSON-Schema derivation's committed fixture (design M0/S2).
+//
+// The derivation fixture is not decoration: it is the record of WHICH schema shapes the generic
+// form can render. If an effect upgrade changes any of it, this test fails and the console's form
+// needs re-checking before the change ships — far cheaper than discovering it on a user's box.
+import { describe, expect, test } from "bun:test";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import { Effect, Layer, Schema } from "effect";
+import { makeConfigService } from "../src/config.js";
+import { pluginInfoLayer } from "../src/host-client.js";
+import { deriveConfigJsonSchema, makeConfigHandler } from "../src/ui-server.js";
+
+/** A representative scanner config: booleans, a string, a string array, a nested object, an enum. */
+const ScannerConfig = Schema.Struct({
+	enabled: Schema.Boolean.annotate({
+		title: "Enable scanning",
+		description: "Whether this source contributes titles.",
+		default: true,
+	}).pipe(
+		Schema.withDecodingDefaultKey(Effect.succeed(true), {
+			encodingStrategy: "omit",
+		}),
+	),
+	root: Schema.optionalKey(
+		Schema.String.annotate({ title: "Launcher root", description: "Absolute path." }),
+	),
+	extraRoots: Schema.Array(Schema.String)
+		.annotate({ title: "Extra roots" })
+		.pipe(
+			Schema.withDecodingDefaultKey(
+				Effect.succeed([] as ReadonlyArray<string>),
+				{ encodingStrategy: "omit" },
+			),
+		),
+	launchers: Schema.Struct({
+		bigpicture: Schema.Boolean.annotate({ title: "Big Picture", default: true }),
+		desktop: Schema.Boolean.annotate({ title: "Desktop", default: false }),
+	}).pipe(
+		Schema.withDecodingDefaultKey(
+			Effect.succeed({ bigpicture: true, desktop: false }),
+			{ encodingStrategy: "omit" },
+		),
+	),
+	pollMinutes: Schema.Int.annotate({
+		title: "Poll interval (minutes)",
+		default: 15,
+	}).pipe(
+		Schema.withDecodingDefaultKey(Effect.succeed(15), {
+			encodingStrategy: "omit",
+		}),
+	),
+	artSource: Schema.Literals(["local", "cdn", "both"])
+		.annotate({ title: "Art source", default: "both" })
+		.pipe(
+			Schema.withDecodingDefaultKey(Effect.succeed("both" as const), {
+				encodingStrategy: "omit",
+			}),
+		),
+});
+
+const props = (): Record<string, Record<string, unknown>> => {
+	const doc = deriveConfigJsonSchema(ScannerConfig) as {
+		schema: { properties: Record<string, Record<string, unknown>> };
+	};
+	return doc.schema.properties;
+};
+
+describe("S2 — JSON Schema derivation for __config", () => {
+	test("derives a renderable form for every shape a scanner config uses", () => {
+		const p = props();
+		expect(p.enabled).toMatchObject({ type: "boolean" });
+		expect(p.root).toMatchObject({ type: "string" });
+		expect(p.extraRoots).toMatchObject({
+			type: "array",
+			items: { type: "string" },
+		});
+		// A nested object stays nested — the form renders a fieldset, not a JSON blob.
+		expect(p.launchers).toMatchObject({
+			type: "object",
+			properties: { bigpicture: { type: "boolean" }, desktop: { type: "boolean" } },
+		});
+		// A literal union derives a clean enum — prefer it over a union of strings.
+		expect(p.artSource).toMatchObject({
+			type: "string",
+			enum: ["local", "cdn", "both"],
+		});
+	});
+
+	test("annotations pass through — they are the ONLY source of labels and defaults", () => {
+		const p = props();
+		expect(p.enabled.title).toBe("Enable scanning");
+		expect(p.enabled.description).toBe("Whether this source contributes titles.");
+		// The derivation does NOT infer `default` from withDecodingDefaultKey, so an un-annotated
+		// field shows the form no placeholder at all. Annotate every field.
+		expect(p.enabled.default).toBe(true);
+		expect(p.artSource.default).toBe("both");
+		// A CHECKED schema (Int is String-plus-a-check) nests its annotations under `allOf`, so a
+		// form reading `default` must merge allOf branches rather than only looking at the top level.
+		expect(p.pollMinutes.allOf).toEqual([
+			{ default: 15, title: "Poll interval (minutes)" },
+		]);
+	});
+
+	test("a decoding default is an Effect, not a thunk — and it actually applies", () => {
+		// The trap this pins: `withDecodingDefaultKey` takes an `Effect`, and passing a bare thunk
+		// (`() => true`) type-checks against the derivation path but blows up at DECODE time with
+		// "Not a valid effect". Deriving a schema is therefore NOT evidence that it works.
+		expect(Schema.decodeUnknownSync(ScannerConfig)({})).toMatchObject({
+			enabled: true,
+			pollMinutes: 15,
+			artSource: "both",
+			launchers: { bigpicture: true, desktop: false },
+		});
+	});
+
+	test("Schema.Int derives a plain integer — Schema.Number does NOT", () => {
+		expect(props().pollMinutes).toMatchObject({ type: "integer" });
+		// The trap, pinned: Schema.Number's ENCODED form admits "NaN"/"Infinity"/"-Infinity", so it
+		// derives a four-way anyOf that no number input can render. Use Finite or Int.
+		const bad = deriveConfigJsonSchema(
+			Schema.Struct({ n: Schema.Number }),
+		) as { schema: { properties: { n: { anyOf?: unknown[] } } } };
+		expect(Array.isArray(bad.schema.properties.n.anyOf)).toBe(true);
+		const ok = deriveConfigJsonSchema(
+			Schema.Struct({ n: Schema.Finite }),
+		) as { schema: { properties: { n: { type?: string } } } };
+		expect(ok.schema.properties.n.type).toBe("number");
+	});
+
+	test("defaulted fields drop out of `required` — the raw file stays default-free", () => {
+		const doc = deriveConfigJsonSchema(ScannerConfig) as {
+			schema: { required?: string[] };
+		};
+		// Every field here either has a decoding default or is optionalKey, so nothing is required.
+		expect(doc.schema.required ?? []).toEqual([]);
+	});
+});
+
+describe("__config wire contract", () => {
+	const withService = async <A>(
+		use: (handler: (req: Request) => Promise<Response>, file: string) => Promise<A>,
+	): Promise<A> => {
+		const dir = fs.mkdtempSync(path.join(os.tmpdir(), "pf-kit-cfg-"));
+		const prev = process.env.PUNKTFUNK_CONFIG_DIR;
+		process.env.PUNKTFUNK_CONFIG_DIR = dir;
+		try {
+			const service = await Effect.runPromise(
+				makeConfigService({ schema: ScannerConfig }).pipe(
+					Effect.provide(
+						Layer.mergeAll(pluginInfoLayer({ name: "steam", version: "0.1.0" })),
+					),
+				),
+			);
+			return await use(
+				makeConfigHandler({ schema: ScannerConfig, service }),
+				service.path,
+			);
+		} finally {
+			if (prev === undefined) delete process.env.PUNKTFUNK_CONFIG_DIR;
+			else process.env.PUNKTFUNK_CONFIG_DIR = prev;
+			fs.rmSync(dir, { recursive: true, force: true });
+		}
+	};
+
+	test("GET answers {schema, value} with an absent file reading as empty", async () => {
+		await withService(async (handler) => {
+			const res = await handler(new Request("http://x/__config"));
+			expect(res.status).toBe(200);
+			const body = (await res.json()) as { schema: unknown; value: unknown };
+			// Both keys are ALWAYS present and never `undefined` — the console decodes this shape,
+			// and an omitted-vs-null field is the wire trap that bit the rom-manager 0.3.1 release.
+			expect(body).toHaveProperty("schema");
+			expect(body).toHaveProperty("value");
+			expect(body.schema).not.toBeNull();
+			// A missing config file is an EMPTY config, not an error.
+			expect(body.value).toEqual({});
+		});
+	});
+
+	test("PUT validates by decode, persists RAW, and never bakes in defaults", async () => {
+		await withService(async (handler, file) => {
+			const res = await handler(
+				new Request("http://x/__config", {
+					method: "PUT",
+					body: JSON.stringify({ enabled: false }),
+				}),
+			);
+			expect(res.status).toBe(200);
+			// The file holds exactly what was authored — the five defaulted fields are NOT written,
+			// which is what keeps a future change to a default from being silently pinned.
+			expect(JSON.parse(fs.readFileSync(file, "utf8"))).toEqual({
+				enabled: false,
+			});
+			const get = (await (
+				await handler(new Request("http://x/__config"))
+			).json()) as { value: unknown };
+			expect(get.value).toEqual({ enabled: false });
+		});
+	});
+
+	test("PUT rejects a body the schema refuses, with the issue, and writes nothing", async () => {
+		await withService(async (handler, file) => {
+			const res = await handler(
+				new Request("http://x/__config", {
+					method: "PUT",
+					body: JSON.stringify({ enabled: "yes please" }),
+				}),
+			);
+			expect(res.status).toBe(400);
+			const body = (await res.json()) as { error: string; issue: string };
+			expect(body.error).toBe("config rejected");
+			expect(body.issue.length).toBeGreaterThan(0);
+			expect(fs.existsSync(file)).toBe(false);
+		});
+	});
+
+	test("PUT rejects a non-JSON body", async () => {
+		await withService(async (handler) => {
+			const res = await handler(
+				new Request("http://x/__config", { method: "PUT", body: "not json" }),
+			);
+			expect(res.status).toBe(400);
+			expect(((await res.json()) as { error: string }).error).toBe(
+				"body must be JSON",
+			);
+		});
+	});
+
+	test("other methods are refused", async () => {
+		await withService(async (handler) => {
+			const res = await handler(
+				new Request("http://x/__config", { method: "DELETE" }),
+			);
+			expect(res.status).toBe(405);
+		});
+	});
+});

plugin-kit/test/library-parity.test.ts

@@ -0,0 +1,186 @@
+// The parity harness is the release gate for every extracted scanner, so the thing that decides
+// pass/fail needs its own tests. The cases below are the ones that actually happen during a port:
+// a lost title, a wrong id, a dropped launch recipe, art whose representation changed but whose
+// presence didn't, and the launcher entries the plugin legitimately adds.
+import { describe, expect, test } from "bun:test";
+import {
+	claimedLibraryId,
+	diffParity,
+	formatParityReport,
+	fromHostEntry,
+	fromProviderEntry,
+	type HostGameEntry,
+} from "../src/library/parity.js";
+import type { ProviderEntry } from "../src/wire.js";
+
+/** What the host reports while its BUILT-IN steam scanner is producing the library. */
+const hostEntry = (over: Partial<HostGameEntry> = {}): HostGameEntry => ({
+	id: "steam:440",
+	store: "steam",
+	title: "Team Fortress 2",
+	launch: { kind: "steam_appid", value: "440" },
+	// The scanner emits host-relative proxy paths the CLIENT resolves.
+	art: {
+		portrait: "/api/v1/library/art/steam:440/portrait",
+		hero: "/api/v1/library/art/steam:440/hero",
+		logo: null,
+		header: "/api/v1/library/art/steam:440/header",
+	},
+	platform: "PC",
+	...over,
+});
+
+/** What the extracted plugin produces for the same title. */
+const pluginEntry = (over: Partial<ProviderEntry> = {}): ProviderEntry =>
+	({
+		external_id: "440",
+		title: "Team Fortress 2",
+		launch: { kind: "steam_appid", value: "440" },
+		// The plugin emits file:// paths and CDN URLs — a DIFFERENT representation of the same art.
+		art: {
+			portrait: "file:///home/u/.steam/appcache/librarycache/440/a/p.jpg",
+			hero: "https://cdn.cloudflare.steamstatic.com/steam/apps/440/library_hero.jpg",
+			header: "https://cdn.cloudflare.steamstatic.com/steam/apps/440/header.jpg",
+		},
+		platform: "PC",
+		...over,
+	}) as ProviderEntry;
+
+describe("id mapping", () => {
+	test("a claimed entry's id is the scanner's id", () => {
+		// The whole migration rests on this one line: Moonlight pins, GameStream app ids and client
+		// art caches are all derived from it.
+		expect(claimedLibraryId("steam", "440")).toBe("steam:440");
+		expect(claimedLibraryId("heroic", "legendary:Quail")).toBe(
+			"heroic:legendary:Quail",
+		);
+	});
+});
+
+describe("diffParity", () => {
+	const base = [fromHostEntry(hostEntry())];
+
+	test("a faithful port passes, even though the art VALUES all changed", () => {
+		const r = diffParity(base, [fromProviderEntry("steam", pluginEntry())]);
+		expect(r.ok).toBe(true);
+		expect(r.matched).toBe(1);
+		expect(r.changed).toEqual([]);
+		expect(formatParityReport(r)).toContain("parity OK");
+	});
+
+	test("a lost title is reported as missing", () => {
+		const r = diffParity(base, []);
+		expect(r.ok).toBe(false);
+		expect(r.missing.map((e) => e.id)).toEqual(["steam:440"]);
+		expect(formatParityReport(r)).toContain("missing:  steam:440");
+	});
+
+	test("a wrong id shows up as BOTH missing and extra — the loudest failure", () => {
+		// The exact shape of the bug this harness exists to catch: the plugin found the title, but
+		// under an id nothing downstream recognizes.
+		const r = diffParity(base, [
+			fromProviderEntry("steam", pluginEntry({ external_id: "440.0" })),
+		]);
+		expect(r.ok).toBe(false);
+		expect(r.missing.map((e) => e.id)).toEqual(["steam:440"]);
+		expect(r.extra.map((e) => e.id)).toEqual(["steam:440.0"]);
+	});
+
+	test("a changed launch recipe is caught", () => {
+		const r = diffParity(base, [
+			fromProviderEntry(
+				"steam",
+				pluginEntry({ launch: { kind: "command", value: "steam" } }),
+			),
+		]);
+		expect(r.ok).toBe(false);
+		expect(r.changed).toEqual([
+			{
+				id: "steam:440",
+				field: "launch",
+				before: "steam_appid:440",
+				after: "command:steam",
+			},
+		]);
+	});
+
+	test("a dropped launch recipe is caught (an unlaunchable tile)", () => {
+		const r = diffParity(base, [
+			fromProviderEntry("steam", pluginEntry({ launch: null })),
+		]);
+		expect(r.changed.map((c) => c.field)).toEqual(["launch"]);
+	});
+
+	test("LOSING an art kind fails; gaining one does not", () => {
+		const lost = diffParity(base, [
+			fromProviderEntry("steam", pluginEntry({ art: { portrait: null } })),
+		]);
+		expect(lost.ok).toBe(false);
+		expect(lost.changed.map((c) => c.field)).toContain("art.portrait");
+
+		// The baseline had no logo; the plugin resolves one. That is an improvement, and failing the
+		// run over it would only train people to ignore the harness.
+		const gained = diffParity(base, [
+			fromProviderEntry(
+				"steam",
+				pluginEntry({
+					art: { ...pluginEntry().art, logo: "file:///l.png" },
+				}),
+			),
+		]);
+		expect(gained.ok).toBe(true);
+	});
+
+	test("metadata drift is caught, but absent-vs-empty is not drift", () => {
+		const changed = diffParity(base, [
+			fromProviderEntry("steam", pluginEntry({ platform: "Linux" })),
+		]);
+		expect(changed.changed).toEqual([
+			{ id: "steam:440", field: "meta.platform", before: "PC", after: "Linux" },
+		]);
+		// The host omits empty lists and nulls; a plugin sending them has changed nothing.
+		const noise = diffParity(base, [
+			fromProviderEntry(
+				"steam",
+				pluginEntry({ genres: [], tags: [], region: null } as never),
+			),
+		]);
+		expect(noise.ok).toBe(true);
+	});
+
+	test("launcher entries are expected extras, not failures", () => {
+		// The built-in scanner had no concept of a launcher entry, so it can never be in the
+		// baseline — reporting it as `extra` would fail every steam run forever.
+		const r = diffParity(base, [
+			fromProviderEntry("steam", pluginEntry()),
+			fromProviderEntry(
+				"steam",
+				pluginEntry({
+					external_id: "ui:bigpicture",
+					title: "Steam Big Picture",
+					role: "launcher",
+					launch: { kind: "steam_ui", value: "bigpicture" },
+					art: {},
+				} as never),
+			),
+		]);
+		expect(r.ok).toBe(true);
+		expect(r.extra).toEqual([]);
+		expect(r.launchersAdded.map((e) => e.id)).toEqual(["steam:ui:bigpicture"]);
+		expect(formatParityReport(r)).toContain("+1 launcher entry");
+	});
+
+	test("an ordinary title the scanner never had IS a failure", () => {
+		// The mirror of the case above: only `role: "launcher"` gets the exemption, so a plugin that
+		// invents games (a bad filter, a tool listed as a game) still fails.
+		const r = diffParity(base, [
+			fromProviderEntry("steam", pluginEntry()),
+			fromProviderEntry(
+				"steam",
+				pluginEntry({ external_id: "228980", title: "Steamworks Common" }),
+			),
+		]);
+		expect(r.ok).toBe(false);
+		expect(r.extra.map((e) => e.id)).toEqual(["steam:228980"]);
+	});
+});

plugin-kit/test/library-parsers.test.ts

@@ -0,0 +1,289 @@
+// The parser ports, tested against the SAME cases the host's Rust scanners pin.
+//
+// These are not "does TypeScript work" tests. The formats here are undocumented and the host's
+// versions are the reference implementation; a port that drifts produces a library that looks fine
+// and launches nothing. Where a Rust test exists, its assertions are carried over verbatim — the
+// per-plugin parity harness (design M5) then checks the whole pipeline against a live host, but
+// these catch a drift long before that.
+import { describe, expect, test } from "bun:test";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import {
+	confinedJoin,
+	crc32,
+	findGridArtFile,
+	findLocalArtFile,
+	fileUrl,
+	gridFilenames,
+	isSteamTool,
+	parseAppManifest,
+	parseRegQuery,
+	parseShortcuts,
+	readTextCapped,
+	shortcutAppId,
+	shortcutGameId,
+	steamCdnUrl,
+	vdfPaths,
+	vdfValue,
+} from "../src/library/parsers/index.js";
+
+const tmp = (name: string): string => {
+	const dir = path.join(os.tmpdir(), `pf-kit-${name}-${process.pid}`);
+	fs.mkdirSync(dir, { recursive: true });
+	return dir;
+};
+
+describe("text VDF / ACF", () => {
+	test("vdfValue extracts a quoted field", () => {
+		expect(vdfValue('"path"\t\t"/mnt/games/SteamLibrary"', "path")).toBe(
+			"/mnt/games/SteamLibrary",
+		);
+		expect(vdfValue('"appid"\t\t"570"', "appid")).toBe("570");
+		expect(vdfValue('"name"\t\t"Dota 2"', "name")).toBe("Dota 2");
+		// Wrong key → nothing (a prefix match must not leak the neighbouring field).
+		expect(vdfValue('"installdir"\t\t"x"', "appid")).toBeUndefined();
+	});
+
+	test("vdfPaths pulls every library folder and unescapes Windows separators", () => {
+		const vdf = `
+"libraryfolders"
+{
+	"0"
+	{
+		"path"		"/home/u/.local/share/Steam"
+		"label"		""
+	}
+	"1"
+	{
+		"path"		"D:\\\\SteamLibrary"
+	}
+}`;
+		expect(vdfPaths(vdf)).toEqual([
+			"/home/u/.local/share/Steam",
+			"D:\\SteamLibrary",
+		]);
+	});
+
+	test("parseAppManifest reads the flat fields it needs", () => {
+		const acf = `"AppState"
+{
+	"appid"		"570"
+	"name"		"Dota 2"
+	"installdir"		"dota 2 beta"
+}`;
+		expect(parseAppManifest(acf)).toEqual({
+			appid: 570,
+			name: "Dota 2",
+			installdir: "dota 2 beta",
+		});
+		// A manifest missing the essentials is not a title.
+		expect(parseAppManifest('"AppState" { "name" "x" }')).toBeUndefined();
+	});
+
+	test("isSteamTool keeps runtimes out of a game library", () => {
+		expect(isSteamTool(228980, "Steamworks Common Redistributables")).toBe(true);
+		expect(isSteamTool(1628350, "Steam Linux Runtime 3.0 (sniper)")).toBe(true);
+		expect(isSteamTool(999, "Proton 9.0")).toBe(true);
+		expect(isSteamTool(999, "SteamVR")).toBe(true);
+		expect(isSteamTool(570, "Dota 2")).toBe(false);
+	});
+});
+
+describe("binary shortcuts.vdf", () => {
+	/** Build a binary shortcuts.vdf the way Steam writes one. */
+	const buildShortcuts = (
+		entries: ReadonlyArray<{
+			appid?: number;
+			appname: string;
+			exe: string;
+			hidden?: boolean;
+		}>,
+	): Uint8Array => {
+		const parts: number[] = [];
+		const cstr = (s: string) => {
+			for (const b of new TextEncoder().encode(s)) parts.push(b);
+			parts.push(0);
+		};
+		const i32 = (v: number) => {
+			parts.push(v & 0xff, (v >>> 8) & 0xff, (v >>> 16) & 0xff, (v >>> 24) & 0xff);
+		};
+		parts.push(0x00);
+		cstr("shortcuts");
+		entries.forEach((e, i) => {
+			parts.push(0x00);
+			cstr(String(i));
+			if (e.appid !== undefined) {
+				parts.push(0x02);
+				cstr("appid");
+				i32(e.appid);
+			}
+			parts.push(0x01);
+			cstr("AppName");
+			cstr(e.appname);
+			parts.push(0x01);
+			cstr("Exe");
+			cstr(e.exe);
+			parts.push(0x02);
+			cstr("IsHidden");
+			i32(e.hidden ? 1 : 0);
+			// A nested map the parser must skip wholesale.
+			parts.push(0x00);
+			cstr("tags");
+			parts.push(0x01);
+			cstr("0");
+			cstr("favourite");
+			parts.push(0x08);
+			parts.push(0x08); // end of this shortcut
+		});
+		parts.push(0x08); // end of shortcuts
+		parts.push(0x08); // end of document
+		return new Uint8Array(parts);
+	};
+
+	test("parses entries, skips nested maps, and reads the hidden flag", () => {
+		const buf = buildShortcuts([
+			{ appid: 2456789012, appname: "My Emulator", exe: '"/usr/bin/foo"' },
+			{ appid: 3000000000, appname: "Hidden One", exe: '"/x"', hidden: true },
+		]);
+		const got = parseShortcuts(buf);
+		expect(got).toHaveLength(2);
+		expect(got[0]).toMatchObject({
+			appid: 2456789012,
+			name: "My Emulator",
+			hidden: false,
+		});
+		expect(got[1]).toMatchObject({ name: "Hidden One", hidden: true });
+	});
+
+	test("derives the appid when the file omits it", () => {
+		const buf = buildShortcuts([{ appname: "No Appid", exe: '"/usr/bin/x"' }]);
+		const got = parseShortcuts(buf);
+		expect(got).toHaveLength(1);
+		// Derived ids always carry the high bit — that is how a shortcut is told apart from a real
+		// store appid downstream (and why its CDN art fetch is skipped).
+		expect(got[0].appid & 0x8000_0000).not.toBe(0);
+		expect(got[0].appid).toBe(shortcutAppId('"/usr/bin/x"', "No Appid"));
+	});
+
+	test("is total on a truncated or garbled file", () => {
+		expect(parseShortcuts(new Uint8Array([]))).toEqual([]);
+		expect(parseShortcuts(new Uint8Array([0x01, 0x02, 0x03]))).toEqual([]);
+		const good = buildShortcuts([{ appid: 1, appname: "A", exe: "/a" }]);
+		// Every truncation of a valid file must return, not throw.
+		for (let i = 0; i < good.length; i++) {
+			expect(() => parseShortcuts(good.subarray(0, i))).not.toThrow();
+		}
+	});
+
+	test("crc32 matches the IEEE check value", () => {
+		// The canonical CRC-32 check: crc32("123456789") == 0xCBF43926.
+		expect(crc32(new TextEncoder().encode("123456789"))).toBe(0xcbf4_3926);
+	});
+
+	test("shortcutGameId composes the appid and the shortcut marker", () => {
+		// high dword = appid, low dword = 0x02000000. Handing rungameid the bare 32-bit appid does
+		// NOT launch a shortcut, which is the entire reason this function exists.
+		const id = BigInt(shortcutGameId(0x8000_0000));
+		expect(id >> 32n).toBe(0x8000_0000n);
+		expect(id & 0xffff_ffffn).toBe(0x0200_0000n);
+		// Digits only — it rides the `steam_appid` launch kind, which the host validates as digits.
+		expect(shortcutGameId(2_456_789_012)).toMatch(/^\d+$/);
+	});
+});
+
+describe("path confinement", () => {
+	test("confinedJoin refuses anything that could escape the install dir", () => {
+		const base = path.join(path.sep, "games", "W3");
+		expect(confinedJoin(base, "bin/game.exe")).toBe(
+			path.join(base, "bin", "game.exe"),
+		);
+		expect(confinedJoin(base, "bin\\game.exe")).toBe(
+			path.join(base, "bin", "game.exe"),
+		);
+		// The three shapes a crafted goggame-*.info would use to point elsewhere.
+		expect(confinedJoin(base, "../../windows/system32/cmd.exe")).toBeUndefined();
+		expect(confinedJoin(base, "/etc/passwd")).toBeUndefined();
+		expect(confinedJoin(base, "C:\\Windows\\system32\\cmd.exe")).toBeUndefined();
+		expect(confinedJoin(base, "")).toBeUndefined();
+	});
+});
+
+describe("capped reads", () => {
+	test("readTextCapped refuses an over-cap file and a missing one", () => {
+		const dir = tmp("caps");
+		const small = path.join(dir, "small.txt");
+		fs.writeFileSync(small, "hello");
+		expect(readTextCapped(small)).toBe("hello");
+		expect(readTextCapped(small, 2)).toBeUndefined(); // over the cap
+		expect(readTextCapped(path.join(dir, "nope.txt"))).toBeUndefined();
+		expect(readTextCapped(dir)).toBeUndefined(); // a directory is not a file
+		fs.rmSync(dir, { recursive: true, force: true });
+	});
+});
+
+describe("art locations", () => {
+	test("steamCdnUrl skips shortcut appids, which have no CDN entry", () => {
+		expect(steamCdnUrl(570, "header")).toContain("/570/header.jpg");
+		expect(steamCdnUrl(570, "portrait")).toContain("library_600x900.jpg");
+		// The local cache names the header asset differently from the CDN — pinned because it is
+		// the single most common way to get Steam art wrong.
+		expect(steamCdnUrl(570, "header")).not.toContain("library_header");
+		expect(steamCdnUrl(0x8000_0001, "header")).toBeUndefined();
+	});
+
+	test("grid filenames follow Steam's per-kind naming", () => {
+		expect(gridFilenames(570, "portrait")).toEqual(["570p.png", "570p.jpg"]);
+		expect(gridFilenames(570, "hero")).toEqual(["570_hero.png", "570_hero.jpg"]);
+		expect(gridFilenames(570, "logo")).toEqual(["570_logo.png", "570_logo.jpg"]);
+		expect(gridFilenames(570, "header")).toEqual(["570.png", "570.jpg"]);
+	});
+
+	test("finds cached and user-override art on disk", () => {
+		const dir = tmp("art");
+		const hashDir = path.join(dir, "appcache", "librarycache", "570", "abc123");
+		fs.mkdirSync(hashDir, { recursive: true });
+		fs.writeFileSync(path.join(hashDir, "library_600x900.jpg"), "x");
+		expect(findLocalArtFile(dir, 570, "portrait")).toBe(
+			path.join(hashDir, "library_600x900.jpg"),
+		);
+		expect(findLocalArtFile(dir, 570, "hero")).toBeUndefined();
+
+		const cfg = path.join(dir, "userdata", "1", "config");
+		fs.mkdirSync(path.join(cfg, "grid"), { recursive: true });
+		fs.writeFileSync(path.join(cfg, "grid", "570p.jpg"), "x");
+		expect(findGridArtFile(cfg, 570, "portrait")).toBe(
+			path.join(cfg, "grid", "570p.jpg"),
+		);
+		fs.rmSync(dir, { recursive: true, force: true });
+	});
+
+	test("fileUrl produces the host's local-art contract shape", () => {
+		const u = fileUrl(path.join(path.sep, "home", "u", "My Games", "c.jpg"));
+		expect(u.startsWith("file:///")).toBe(true);
+		// Spaces are percent-encoded; the separators survive so the host can rebuild the path.
+		expect(u).toContain("My%20Games");
+		expect(u).toContain("/c.jpg");
+	});
+});
+
+describe("reg.exe output", () => {
+	test("parses value rows and leaves the key header alone", () => {
+		const stdout = [
+			"",
+			"HKEY_LOCAL_MACHINE\\SOFTWARE\\WOW6432Node\\Valve\\Steam",
+			"    InstallPath    REG_SZ    C:\\Program Files (x86)\\Steam",
+			"    Language    REG_SZ    english",
+			"",
+		].join("\r\n");
+		expect(parseRegQuery(stdout)).toEqual([
+			{
+				name: "InstallPath",
+				type: "REG_SZ",
+				// Data may contain spaces — only the first two columns are split off.
+				data: "C:\\Program Files (x86)\\Steam",
+			},
+			{ name: "Language", type: "REG_SZ", data: "english" },
+		]);
+	});
+});

plugin-kit/tsconfig.json

@@ -10,5 +10,8 @@
 		"noEmit": true,
 		"types": ["bun"]
 	},
-	"include": ["src", "test"]
+	// `examples` is type-checked but never built: tsconfig.build.json narrows to `src`, and
+	// package.json ships only `dist` + README. A worked example that doesn't compile is worse than
+	// no example, and these are what the first-party scanner repos are cut from.
+	"include": ["src", "test", "examples"]
 }

scripts/build-xcframework.sh

@@ -10,18 +10,6 @@
 set -euo pipefail
 cd "$(dirname "$0")/.."
 
-# Opus must be built FROM SOURCE, never picked up from the machine. `audiopus_sys` probes
-# pkg-config first, and a Homebrew libopus is compiled for the HOST macOS — its objects land
-# inside our staticlib carrying that minos (the deployment-target check at the end of this
-# script then fails with 143 SILK objects at the host's version). Whether the bundle is
-# usable would otherwise depend on whether the developer happens to have `brew install opus`,
-# which is exactly the kind of thing an artifact consumed by every Apple build must not
-# depend on. `OPUS_NO_PKG_CONFIG` forces the vendored build; the CMake policy floor is for
-# that vendored copy, whose CMakeLists still declares a pre-3.5 minimum that CMake 4 removed
-# support for.
-export OPUS_NO_PKG_CONFIG=1
-export CMAKE_POLICY_VERSION_MINIMUM="${CMAKE_POLICY_VERSION_MINIMUM:-3.5}"
-
 TARGETS_MAC=(aarch64-apple-darwin x86_64-apple-darwin)
 BUILD_IOS="${BUILD_IOS:-0}" # BUILD_IOS=1 adds iOS device + simulator slices (rustup targets aarch64-apple-ios{,-sim})
 BUILD_TVOS="${BUILD_TVOS:-0}" # BUILD_TVOS=1 adds tvOS slices — TIER-3 Rust targets: needs `rustup toolchain install nightly` + `rustup component add rust-src --toolchain nightly`
@@ -137,14 +125,7 @@ for obj in "$STAGE"/macos/libpunktfunk_core.a; do
     bad=$(otool -l "$obj" 2>/dev/null | awk '/minos/ {print $2}' | sort -uV | awk -F. '$1 > 14' | head -1)
     if [[ -n "$bad" ]]; then
         echo "ERROR: $obj contains objects built for macOS $bad (> 14.0)." >&2
-        echo "Two known causes:" >&2
-        echo "  1. A system libopus linked instead of the vendored one (check the build" >&2
-        echo "     script output for a /opt/homebrew or /usr/local link-search path). This" >&2
-        echo "     script exports OPUS_NO_PKG_CONFIG=1 to prevent it — if you see it anyway," >&2
-        echo "     something overrode that." >&2
-        echo "  2. A stale cache: cargo does not fingerprint MACOSX_DEPLOYMENT_TARGET." >&2
-        echo "     rm -rf target/{aarch64,x86_64}-apple-darwin and rebuild." >&2
-        echo "Identify the offenders with: ar x $obj && otool -l *.o | grep -B1 minos" >&2
+        echo "Stale cache — rm -rf target/{aarch64,x86_64}-apple-darwin and rebuild." >&2
         exit 1
     fi
 done

scripts/punktfunk-scripting.service

@@ -6,9 +6,16 @@
 # SIGTERM interrupts the whole tree STRUCTURALLY, so every plugin's scoped finalizers run before
 # exit (clean deregister / preset release) — hence the generous stop timeout below.
 #
-# OPT-IN — unlike punktfunk-web, the package does NOT auto-enable this: the runner does nothing until
-# you add scripts or install plugins. Turn it on once you have automation to run:
-#   systemctl --user enable --now punktfunk-scripting
+# ON BY DEFAULT — the packages enable this for every user (`systemctl --global enable` from the
+# .deb/.rpm scriptlets; a baked-in default.target.wants symlink in the sysext image). It used to be
+# opt-in, on the reasoning that the runner does nothing until you add scripts or plugins. That
+# stopped being true when the game-library scanners became plugins: the library is a flagship
+# surface, and a host whose runner is off now comes up with an empty library and no obvious reason
+# why (design/library-scanner-plugins.md D9).
+#
+# It remains opt-OUT, per user:
+#   systemctl --user mask punktfunk-scripting
+# (`mask`, not `disable` — a plain disable cannot remove a symlink that lives in /etc or /usr.)
 #
 # Auto-wired like the console: a plugin's connect() reads the host's SCOPED plugin token + identity
 # cert from ~/.config/punktfunk/{plugin-token,cert.pem} (written by the host's `serve`) — no env

sdk/src/ui.ts

@@ -44,6 +44,17 @@ export interface PluginUiOptions {
 	version?: string;
 	/** Optional lucide icon name for the nav entry (`[a-z0-9-]`, e.g. `"gamepad-2"`). */
 	icon?: string;
+	/**
+	 * What KIND of plugin this is (`[a-z][a-z0-9-]{0,31}`). The console groups and filters on it —
+	 * and notably keeps `"library"` plugins **out of the nav**, because a scanner's entry point is
+	 * the Library section's Game sources surface, not a sidebar item of its own. Six installed
+	 * scanners would otherwise flood the sidebar.
+	 *
+	 * `@punktfunk/plugin-kit`'s `defineLibraryPlugin` sets this for you. Set it by hand only if you
+	 * are building a library plugin without the kit — and omit it if your plugin wants a full page
+	 * despite also syncing a library (rom-manager does).
+	 */
+	category?: string;
 	/**
 	 * Directory of the built SPA. Requests are served from here first (with an `index.html` SPA
 	 * fallback for navigations); a static miss falls through to [`fetch`]. Accepts a filesystem
@@ -182,6 +193,9 @@ export const servePluginUi = async (
 			secret,
 			...(opts.icon !== undefined ? { icon: opts.icon } : {}),
 		},
+		// Sent through the UNTYPED `pf.request` below, so an older host simply ignores the unknown
+		// field rather than rejecting the registration — no runner flag, no version gate.
+		...(opts.category !== undefined ? { category: opts.category } : {}),
 	};
 
 	const register = () => pf.request("PUT", `/plugins/${opts.id}`, body);

web/messages/de.json

@@ -10,11 +10,11 @@
 	"nav_library": "Bibliothek",
 	"nav_plugins": "Plugins",
 	"plugin_offline_title": "Dieses Plugin läuft nicht",
-	"plugin_origin_untrusted_title": "Port dieses Plugins einmal best\u00e4tigen",
-	"plugin_origin_untrusted_hint": "Plugin-Oberfl\u00e4chen laufen auf einem eigenen Port, damit ein Plugin nicht in deinem Namen auf der Konsole handeln kann. Dein Browser vertraut dem Zertifikat dieses Hosts f\u00fcr den Konsolen-Port, aber noch nicht f\u00fcr diesen — und in einem Frame kann er nicht nachfragen. \u00d6ffne ihn einmal in einem Tab, best\u00e4tige das Zertifikat und komm zur\u00fcck.",
-	"plugin_origin_untrusted_open": "In neuem Tab \u00f6ffnen",
-	"plugin_origin_unavailable_title": "Plugin-Oberfl\u00e4chen sind nicht verf\u00fcgbar",
-	"plugin_origin_unavailable_hint": "Plugin-Oberfl\u00e4chen laufen auf einem eigenen Port, damit ein Plugin nicht in deinem Namen auf der Konsole handeln kann. Dieser Port konnte nicht ge\u00f6ffnet werden, deshalb bleiben sie deaktiviert. Sieh ins Konsolen-Log, setze dann PUNKTFUNK_UI_PLUGIN_PORT auf einen freien Port und starte neu.",
+	"plugin_origin_untrusted_title": "Port dieses Plugins einmal bestätigen",
+	"plugin_origin_untrusted_hint": "Plugin-Oberflächen laufen auf einem eigenen Port, damit ein Plugin nicht in deinem Namen auf der Konsole handeln kann. Dein Browser vertraut dem Zertifikat dieses Hosts für den Konsolen-Port, aber noch nicht für diesen — und in einem Frame kann er nicht nachfragen. Öffne ihn einmal in einem Tab, bestätige das Zertifikat und komm zurück.",
+	"plugin_origin_untrusted_open": "In neuem Tab öffnen",
+	"plugin_origin_unavailable_title": "Plugin-Oberflächen sind nicht verfügbar",
+	"plugin_origin_unavailable_hint": "Plugin-Oberflächen laufen auf einem eigenen Port, damit ein Plugin nicht in deinem Namen auf der Konsole handeln kann. Dieser Port konnte nicht geöffnet werden, deshalb bleiben sie deaktiviert. Sieh ins Konsolen-Log, setze dann PUNKTFUNK_UI_PLUGIN_PORT auf einen freien Port und starte neu.",
 	"plugin_offline_hint": "Starte den Scripting-Runner und versuche es erneut.",
 	"plugin_retry": "Erneut versuchen",
 	"plugin_open_new_tab": "In neuem Tab öffnen",
@@ -276,7 +276,7 @@
 	"library_field_command": "Startbefehl",
 	"library_field_command_help": "Optional. Der Befehl, mit dem der Host diesen Titel startet.",
 	"library_field_password": "Konsolen-Passwort",
-	"library_field_password_help": "Ein Startbefehl l\u00e4uft auf dem Host mit deinen Rechten. Best\u00e4tige zum Speichern dein Konsolen-Passwort.",
+	"library_field_password_help": "Ein Startbefehl läuft auf dem Host mit deinen Rechten. Bestätige zum Speichern dein Konsolen-Passwort.",
 	"library_field_platform": "Plattform",
 	"library_field_platform_help": "Das System, auf dem dieser Titel läuft, z. B. PS2, Xbox 360, SNES, PC.",
 	"library_field_description": "Beschreibung",
@@ -292,9 +292,25 @@
 	"library_field_players": "Spieler",
 	"library_details_legend": "Details (optional)",
 	"library_owned_by": "über {provider}",
-	"library_providers_title": "Von Plugins synchronisiert",
-	"library_providers_help": "Diese Einträge gehören einem Plugin und lassen sich deshalb nicht einzeln bearbeiten oder löschen — das Plugin synchronisiert sie neu. Ist das Plugin weg, entferne seine Einträge hier.",
 	"library_provider_count": "{count} Einträge",
+	"library_launchers_title": "Launcher",
+	"library_empty_add_source": "Füge unten eine Spielquelle hinzu, damit deine installierten Spiele hier erscheinen.",
+	"library_add_source": "Quelle hinzufügen",
+	"library_source_detected": "Erkannt",
+	"library_source_running": "Läuft",
+	"library_source_stopped": "Gestoppt",
+	"library_source_settings": "Einstellungen",
+	"library_source_settings_title": "Einstellungen für {source}",
+	"library_source_settings_save": "Einstellungen speichern",
+	"library_source_settings_saved": "Einstellungen gespeichert.",
+	"library_source_settings_failed": "Einstellungen konnten nicht gespeichert werden: {issue}",
+	"library_source_settings_unreachable": "Die Einstellungen dieser Quelle sind nicht erreichbar: {issue}",
+	"library_source_settings_json_hint": "Die Einstellungen dieser Quelle passen in kein einfaches Formular — bearbeite sie als JSON. Sie werden vor dem Speichern geprüft.",
+	"library_migrate_title": "Spielquellen werden zu Plugins",
+	"library_migrate_help": "Jeder Launcher wird ein eigenes Add-on — du installierst nur die, die du nutzt, und jedes bekommt eigene Einstellungen. Installierst du eines, übernimmt es vom eingebauten Scanner; deine Spiele behalten ihre Kacheln. Wenn du nichts tust, ändert sich nichts.",
+	"library_migrate_install": "Quelle {source} installieren",
+	"library_source_installing": "{title} wird installiert…",
+	"library_source_install_failed": "Diese Quelle konnte nicht installiert werden.",
 	"library_provider_filter": "Nur diese zeigen",
 	"library_provider_show_all": "Alle zeigen",
 	"library_provider_purge": "Einträge dieses Anbieters entfernen",
@@ -585,5 +601,7 @@
 	"update_result_noop": "Deine Paketquelle hatte noch nichts Neueres — in ein paar Minuten erneut versuchen.",
 	"update_opt_in": "Um Ein-Klick-Updates von hier zu aktivieren, einmal auf dem Host ausführen (danach ab- und wieder anmelden):",
 	"update_result_failed": "Update auf {to} ist in Phase {stage} fehlgeschlagen.",
-	"update_result_log": "Installer-Log:"
+	"update_result_log": "Installer-Log:",
+	"library_field_role": "Dieser Eintrag öffnet einen Launcher",
+	"library_field_role_help": "Zeigt ihn in der Launcher-Reihe über deinen Spielen statt im Raster. Er startet und endet genauso wie sonst."
 }

web/messages/en.json

@@ -292,9 +292,25 @@
 	"library_field_players": "Players",
 	"library_details_legend": "Details (optional)",
 	"library_owned_by": "via {provider}",
-	"library_providers_title": "Synced by plugins",
-	"library_providers_help": "These entries are owned by a plugin, so they can't be edited or removed one at a time — the plugin re-syncs them. If the plugin is gone, remove its entries here.",
 	"library_provider_count": "{count} entries",
+	"library_launchers_title": "Launchers",
+	"library_empty_add_source": "Add a game source below to see your installed games here.",
+	"library_add_source": "Add a source",
+	"library_source_detected": "Detected",
+	"library_source_running": "Running",
+	"library_source_stopped": "Stopped",
+	"library_source_settings": "Settings",
+	"library_source_settings_title": "{source} settings",
+	"library_source_settings_save": "Save settings",
+	"library_source_settings_saved": "Settings saved.",
+	"library_source_settings_failed": "Could not save the settings: {issue}",
+	"library_source_settings_unreachable": "Could not reach this source's settings: {issue}",
+	"library_source_settings_json_hint": "This source's settings don't fit a simple form, so edit them as JSON. They're checked before saving.",
+	"library_migrate_title": "Game sources are moving to plugins",
+	"library_migrate_help": "Each launcher is becoming its own add-on, so you only install the ones you use — and each gets its own settings. Install one and it takes over from the built-in scanner; your games keep the same tiles. Nothing changes if you do nothing yet.",
+	"library_migrate_install": "Install the {source} source",
+	"library_source_installing": "Installing {title}…",
+	"library_source_install_failed": "Could not install this source.",
 	"library_provider_filter": "Show only these",
 	"library_provider_show_all": "Show all",
 	"library_provider_purge": "Remove this provider's entries",
@@ -585,5 +601,7 @@
 	"update_result_noop": "Your package source had nothing newer yet — try again in a few minutes.",
 	"update_opt_in": "To enable one-click updates from here, run this once on the host (then log out and back in):",
 	"update_result_failed": "Update to {to} failed during {stage}.",
-	"update_result_log": "Installer log:"
+	"update_result_log": "Installer log:",
+	"library_field_role": "This entry opens a launcher",
+	"library_field_role_help": "Shows it in the Launchers row above your games instead of in the grid. It still starts and stops the same way."
 }

web/src/api/plugins.ts

@@ -29,8 +29,18 @@ export interface PluginSummary {
 	version?: string;
 	/** Present iff the plugin serves a UI (and thus gets a nav entry). */
 	ui?: PluginUiSummary;
+	/**
+	 * What kind of plugin this is. The console knows one value — `"library"` — and keeps those OUT
+	 * of the nav: a scanner's entry point is the Library section's Game sources surface, and six
+	 * installed scanners would otherwise flood the sidebar (design D5). Absent on an older host, and
+	 * absent by choice for a plugin that wants its own page anyway (rom-manager).
+	 */
+	category?: string;
 }
 
+/** The one category the console treats specially. */
+export const LIBRARY_CATEGORY = "library";
+
 // A curated lucide set for plugin nav icons. Importing lucide's full dynamic icon map would defeat
 // tree-shaking (U-S4), so a plugin picks a name from here; anything unknown falls back to Puzzle.
 const ICONS: Record<string, LucideIcon> = {
@@ -97,6 +107,18 @@ export function usePlugins() {
 	});
 }
 
-/** Only the plugins that surface a UI — the ones that get a nav entry. */
+/**
+ * The plugins that get a **nav entry**: those serving a UI, minus the library-category ones.
+ *
+ * A library plugin still serves a UI port (that is how `__config` is reached) and its
+ * `/plugins/$pluginId/$` route still resolves, so an existing deep link keeps working — it simply
+ * isn't advertised in the sidebar.
+ */
 export const uiPlugins = (list: PluginSummary[] | undefined): PluginSummary[] =>
-	(list ?? []).filter((p) => p.ui);
+	(list ?? []).filter((p) => p.ui && p.category !== LIBRARY_CATEGORY);
+
+/** The installed library-category plugins — the Game sources surface's own list. */
+export const libraryPlugins = (
+	list: PluginSummary[] | undefined,
+): PluginSummary[] =>
+	(list ?? []).filter((p) => p.category === LIBRARY_CATEGORY);

web/src/api/store.ts

@@ -69,6 +69,17 @@ export interface StoreEntry {
 	installed_version?: string;
 	update_available: boolean;
 	blocked?: string;
+	/**
+	 * What kind of plugin this is. Browse filters on these, and the Library section's "Add a source"
+	 * rail shows exactly the `library` ones (design D5/D6). Absent on an index that predates them.
+	 */
+	categories?: string[];
+	/**
+	 * Whether the launcher this plugin scans looks installed on this host, from the index's own
+	 * existence probes (design D8). `undefined` = the entry declares no probes for this platform,
+	 * which is "unknown" and must render differently from "not installed".
+	 */
+	detected?: boolean;
 }
 
 export interface StoreCatalog {

web/src/sections/Library/GameForm.tsx

@@ -27,6 +27,10 @@ interface FormState {
 	 *  own comment at the render site (2026-08-05 review M-6). Never round-tripped from the
 	 *  server, so it is always empty on open, including when editing an entry that has one. */
 	password: string;
+	/** `true` = this entry opens a launcher rather than a game (design D4). Purely presentational:
+	 *  the console groups launcher entries into their own rail, and clients that don't know the
+	 *  field render them as ordinary tiles. */
+	isLauncher: boolean;
 	// Details — the flattened GameMeta fields; numbers and lists are kept as the raw
 	// text the user typed and only parsed on submit.
 	platform: string;
@@ -48,6 +52,7 @@ const emptyForm: FormState = {
 	logo: "",
 	command: "",
 	password: "",
+	isLauncher: false,
 	platform: "",
 	description: "",
 	developer: "",
@@ -68,6 +73,9 @@ function formFrom(entry: GameEntry): FormState {
 		logo: entry.art.logo ?? "",
 		command: entry.launch?.kind === "command" ? entry.launch.value : "",
 		password: "",
+		// Round-tripped like every other field: `update_custom` REPLACES the whole entry, so an
+		// unread field here would silently demote a launcher entry back to a game on any edit.
+		isLauncher: entry.role === "launcher",
 		platform: entry.platform ?? "",
 		description: entry.description ?? "",
 		developer: entry.developer ?? "",
@@ -113,6 +121,8 @@ function toInput(f: FormState): CustomInput {
 		// The BFF re-verifies this and strips it before forwarding; the host never sees the field.
 		// Only sent when there is a command to authorize, matching the conditional gate.
 		...(command ? { password: f.password } : {}),
+		// Omitted when it is the default, matching the host's skip-when-`game` serialization.
+		...(f.isLauncher ? { role: "launcher" as const } : {}),
 		platform: trim(f.platform),
 		description: trim(f.description),
 		developer: trim(f.developer),
@@ -297,6 +307,26 @@ export const GameForm: FC<{
 							required
 						/>
 					)}
+					{/* Design D4: a launcher entry opens the launcher itself rather than a title. It
+					    launches and leases like any other entry — this only moves it into the
+					    console's Launchers rail. Hand-adding one is the supported way to get a
+					    "Heroic" or "Lutris" tile without installing that source's plugin. */}
+					<div className="space-y-2">
+						<div className="flex items-center gap-2">
+							<input
+								id="lib-isLauncher"
+								type="checkbox"
+								checked={form.isLauncher}
+								onChange={(e) =>
+									setForm((f) => ({ ...f, isLauncher: e.target.checked }))
+								}
+							/>
+							<Label htmlFor="lib-isLauncher">{m.library_field_role()}</Label>
+						</div>
+						<p className="text-xs text-muted-foreground">
+							{m.library_field_role_help()}
+						</p>
+					</div>
 					<fieldset className="space-y-4 border-t pt-2">
 						<legend className="sr-only">{m.library_details_legend()}</legend>
 						<p

web/src/sections/Library/LibraryGrid.tsx

@@ -82,14 +82,42 @@ export const LibraryGrid: FC<{
 	/** Custom id of the card whose delete is in flight, or null — only that card disables. */
 	deletingId: string | null;
 }> = ({ library, onEdit, onDelete, deletingId }) => {
-	const games = library.data ?? [];
+	const all = library.data ?? [];
+	// Launcher entries (design D4) open the launcher itself — Steam Big Picture, Heroic — rather than
+	// a title. They launch and lease exactly like games; grouping them into their own rail is purely
+	// so a shelf of 400 games doesn't bury the two or three ways to open a launcher.
+	const launchers = all.filter((g) => g.role === "launcher");
+	const games = all.filter((g) => g.role !== "launcher");
+	const card = (game: GameEntry) => (
+		<GameCard
+			key={game.id}
+			game={game}
+			onEdit={() => onEdit(game)}
+			onDelete={() => onDelete(game)}
+			deleting={deletingId === customId(game)}
+		/>
+	);
 	return (
 		<QueryState
 			isLoading={library.isLoading}
 			error={library.error}
 			refetch={library.refetch}
 		>
-			{games.length === 0 ? (
+			{launchers.length > 0 && (
+				<div className="@container mb-card">
+					<p className="pb-2 text-xs font-medium uppercase tracking-wide text-muted-foreground/70">
+						{m.library_launchers_title()}
+					</p>
+					<motion.div
+						transition={{ delayChildren: stagger(0.1) }}
+						variants={{ enter: {}, from: {} }}
+						className="grid grid-cols-1 gap-card @sm:grid-cols-2 @md:grid-cols-2 @lg:grid-cols-3 @2xl:grid-cols-4 @4xl:grid-cols-5"
+					>
+						{launchers.map(card)}
+					</motion.div>
+				</div>
+			)}
+			{all.length === 0 ? (
 				<Card>
 					{/* `flush`, not a bare `p-8`: the default `sm:pt-0` would survive the override
 					    (tailwind-merge only resolves conflicts within a variant) and eat the top
@@ -98,27 +126,25 @@ export const LibraryGrid: FC<{
 						flush
 						className="p-8 text-center text-sm text-muted-foreground"
 					>
-						{m.library_empty()}
+						{/* After extraction a fresh host has NO scanners at all, so "no games" is the
+						    expected first-run state rather than a fault. Point at the fix (design D9)
+						    instead of leaving a bare empty grid. */}
+						<p>{m.library_empty()}</p>
+						<p className="mt-2">{m.library_empty_add_source()}</p>
 					</CardContent>
 				</Card>
 			) : (
-				<div className="@container">
-					<motion.div
-						transition={{ delayChildren: stagger(0.1) }}
-						variants={{ enter: {}, from: {} }}
-						className="grid grid-cols-1 gap-card @sm:grid-cols-2 @md:grid-cols-2 @lg:grid-cols-3 @2xl:grid-cols-4 @4xl:grid-cols-5"
-					>
-						{games.map((game) => (
-							<GameCard
-								key={game.id}
-								game={game}
-								onEdit={() => onEdit(game)}
-								onDelete={() => onDelete(game)}
-								deleting={deletingId === customId(game)}
-							/>
-						))}
-					</motion.div>
-				</div>
+				games.length > 0 && (
+					<div className="@container">
+						<motion.div
+							transition={{ delayChildren: stagger(0.1) }}
+							variants={{ enter: {}, from: {} }}
+							className="grid grid-cols-1 gap-card @sm:grid-cols-2 @md:grid-cols-2 @lg:grid-cols-3 @2xl:grid-cols-4 @4xl:grid-cols-5"
+						>
+							{games.map(card)}
+						</motion.div>
+					</div>
+				)
 			)}
 		</QueryState>
 	);

web/src/sections/Library/Providers.tsx

@@ -1,104 +0,0 @@
-import { useQueryClient } from "@tanstack/react-query";
-import { toast } from "@unom/ui/toast";
-import { Trash2 } from "lucide-react";
-import type { FC } from "react";
-import {
-	getGetLibraryQueryKey,
-	useDeleteProviderEntries,
-} from "@/api/gen/library/library";
-import type { GameEntry } from "@/api/gen/model/gameEntry";
-import { Badge } from "@/components/ui/badge";
-import { Button } from "@/components/ui/button";
-import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
-import { apiErrorMessage } from "@/lib/errors";
-import { m } from "@/paraglide/messages";
-
-/**
- * Provider-owned entries: who put them there, and how to get rid of them.
- *
- * A plugin can sync entries into the library (RFC §8) and they are then refused to hand-edit or
- * delete individually — the host answers 409 and points at the provider's own reconcile. Which is
- * correct, and completely opaque if the plugin is gone: uninstalling it leaves its games in the
- * library with no console-side way to remove them. `DELETE /library/provider/{provider}` is the
- * documented clean-uninstall path and nothing called it.
- *
- * Renders nothing when no entry carries a provider, so an ordinary library sees no extra chrome.
- */
-export const ProvidersCard: FC<{
-	entries: GameEntry[];
-	/** The provider currently filtered to, or null for "everything". */
-	active: string | null;
-	onFilter: (provider: string | null) => void;
-}> = ({ entries, active, onFilter }) => {
-	const qc = useQueryClient();
-	const purge = useDeleteProviderEntries();
-
-	// Count per provider, in first-seen order — the list is small and operator-facing.
-	const counts = new Map<string, number>();
-	for (const e of entries) {
-		if (e.provider) counts.set(e.provider, (counts.get(e.provider) ?? 0) + 1);
-	}
-	if (counts.size === 0) return null;
-
-	const onPurge = async (provider: string, count: number) => {
-		if (!confirm(m.library_provider_purge_confirm({ provider, count }))) return;
-		try {
-			await purge.mutateAsync({ provider });
-			// The host emits `library.changed`, but don't wait for the round trip to redraw.
-			qc.invalidateQueries({ queryKey: getGetLibraryQueryKey() });
-			if (active === provider) onFilter(null);
-			toast.success(m.library_provider_purged({ provider }));
-		} catch (e) {
-			toast.error(apiErrorMessage(e) ?? m.library_provider_purge_failed());
-		}
-	};
-
-	return (
-		<Card>
-			<CardHeader>
-				<CardTitle>{m.library_providers_title()}</CardTitle>
-			</CardHeader>
-			<CardContent className="space-y-3">
-				<p className="max-w-prose text-sm text-muted-foreground">
-					{m.library_providers_help()}
-				</p>
-				<div className="flex flex-col gap-2">
-					{[...counts.entries()].map(([provider, count]) => (
-						<div
-							key={provider}
-							className="flex flex-wrap items-center gap-3 rounded-lg border p-3"
-						>
-							<span className="font-medium">{provider}</span>
-							<Badge variant="secondary">
-								{m.library_provider_count({ count })}
-							</Badge>
-							<div className="ml-auto flex gap-2">
-								<Button
-									size="sm"
-									variant={active === provider ? "default" : "outline"}
-									aria-pressed={active === provider}
-									onClick={() =>
-										onFilter(active === provider ? null : provider)
-									}
-								>
-									{active === provider
-										? m.library_provider_show_all()
-										: m.library_provider_filter()}
-								</Button>
-								<Button
-									size="sm"
-									variant="outline"
-									disabled={purge.isPending}
-									aria-label={m.library_provider_purge()}
-									onClick={() => onPurge(provider, count)}
-								>
-									<Trash2 className="size-4 text-destructive" />
-								</Button>
-							</div>
-						</div>
-					))}
-				</div>
-			</CardContent>
-		</Card>
-	);
-};

web/src/sections/Library/SourceSettings.tsx

@@ -0,0 +1,345 @@
+import { toast } from "@unom/ui/toast";
+import { type FC, useEffect, useState } from "react";
+import type { ScannerInfo } from "@/api/gen/model/scannerInfo";
+import { Button } from "@/components/ui/button";
+import {
+	Dialog,
+	DialogContent,
+	DialogHeader,
+	DialogTitle,
+} from "@/components/ui/dialog";
+import { Input } from "@/components/ui/input";
+import { Label } from "@/components/ui/label";
+import { Spinner } from "@/components/ui/spinner";
+import { m } from "@/paraglide/messages";
+
+/**
+ * A library source's settings, rendered as a **generic form** from the plugin's own JSON Schema.
+ *
+ * The point (design D7, closing G8): a scanner plugin ships no SPA at all. It serves
+ * `GET/PUT /__config` from the kit, and the console renders whatever schema comes back. Everything
+ * goes through the existing session-gated `/plugin-ui/<id>/…` proxy, so there is **zero new host
+ * surface** — the browser never learns the plugin's port or secret.
+ *
+ * Fields the derivation can't express fall back to a raw JSON editor. That fallback is what bounds
+ * the risk of the whole approach: worst case the drawer is a validated textarea, and the PUT still
+ * validates by decode host-side either way.
+ */
+export const SourceSettingsDialog: FC<{
+	source: ScannerInfo;
+	onClose: () => void;
+}> = ({ source, onClose }) => {
+	const pluginId = source.provider ?? source.id;
+	const [state, setState] = useState<
+		| { tag: "loading" }
+		| { tag: "error"; message: string }
+		| { tag: "ready"; schema: JsonSchemaDoc | null; value: JsonObject }
+	>({ tag: "loading" });
+	const [raw, setRaw] = useState("");
+	const [saving, setSaving] = useState(false);
+
+	useEffect(() => {
+		let cancelled = false;
+		(async () => {
+			try {
+				const res = await fetch(`/plugin-ui/${pluginId}/__config`, {
+					credentials: "same-origin",
+				});
+				if (!res.ok) throw new Error(`HTTP ${res.status}`);
+				const body = (await res.json()) as {
+					schema: JsonSchemaDoc | null;
+					value: JsonObject | null;
+				};
+				if (cancelled) return;
+				const value = body.value ?? {};
+				setState({ tag: "ready", schema: body.schema, value });
+				setRaw(JSON.stringify(value, null, 2));
+			} catch (e) {
+				if (!cancelled) {
+					setState({ tag: "error", message: String(e) });
+				}
+			}
+		})();
+		return () => {
+			cancelled = true;
+		};
+	}, [pluginId]);
+
+	const save = async (value: JsonObject) => {
+		setSaving(true);
+		try {
+			const res = await fetch(`/plugin-ui/${pluginId}/__config`, {
+				method: "PUT",
+				credentials: "same-origin",
+				headers: { "content-type": "application/json" },
+				body: JSON.stringify(value),
+			});
+			if (!res.ok) {
+				const body = (await res.json().catch(() => null)) as {
+					issue?: string;
+				} | null;
+				throw new Error(body?.issue ?? `HTTP ${res.status}`);
+			}
+			toast.success(m.library_source_settings_saved());
+			onClose();
+		} catch (e) {
+			toast.error(m.library_source_settings_failed({ issue: String(e) }));
+		} finally {
+			setSaving(false);
+		}
+	};
+
+	return (
+		<Dialog open onOpenChange={(open) => !open && onClose()}>
+			<DialogContent>
+				<DialogHeader>
+					<DialogTitle>
+						{m.library_source_settings_title({ source: source.label })}
+					</DialogTitle>
+				</DialogHeader>
+				{state.tag === "loading" && <Spinner />}
+				{state.tag === "error" && (
+					<p className="text-sm text-destructive">
+						{m.library_source_settings_unreachable({ issue: state.message })}
+					</p>
+				)}
+				{state.tag === "ready" && (
+					<ConfigForm
+						schema={state.schema}
+						value={state.value}
+						raw={raw}
+						onRaw={setRaw}
+						saving={saving}
+						onSave={save}
+					/>
+				)}
+			</DialogContent>
+		</Dialog>
+	);
+};
+
+type JsonObject = Record<string, unknown>;
+
+interface JsonSchemaNode {
+	type?: string;
+	title?: string;
+	description?: string;
+	default?: unknown;
+	enum?: string[];
+	properties?: Record<string, JsonSchemaNode>;
+	items?: JsonSchemaNode;
+	allOf?: JsonSchemaNode[];
+}
+
+interface JsonSchemaDoc {
+	schema?: JsonSchemaNode;
+}
+
+/**
+ * Flatten a node's `allOf` branches into it. A *checked* schema (effect's `Schema.Int`, or anything
+ * with `.check(...)`) nests its annotations and constraints there rather than at the top level, so
+ * a form that only reads the top level silently loses every title and default on those fields.
+ */
+const flatten = (node: JsonSchemaNode): JsonSchemaNode =>
+	(node.allOf ?? []).reduce<JsonSchemaNode>(
+		(acc, branch) => ({ ...acc, ...branch }),
+		{ ...node },
+	);
+
+/** Can this field be rendered as a real input? Anything else sends the whole form to the editor. */
+const renderable = (node: JsonSchemaNode): boolean => {
+	const n = flatten(node);
+	if (n.enum) return true;
+	if (n.type === "boolean" || n.type === "string") return true;
+	if (n.type === "number" || n.type === "integer") return true;
+	if (n.type === "array" && flatten(n.items ?? {}).type === "string") return true;
+	if (n.type === "object" && n.properties) {
+		return Object.values(n.properties).every(renderable);
+	}
+	return false;
+};
+
+const ConfigForm: FC<{
+	schema: JsonSchemaDoc | null;
+	value: JsonObject;
+	raw: string;
+	onRaw: (v: string) => void;
+	saving: boolean;
+	onSave: (value: JsonObject) => void;
+}> = ({ schema, value, raw, onRaw, saving, onSave }) => {
+	const [draft, setDraft] = useState<JsonObject>(value);
+	const root = schema?.schema ? flatten(schema.schema) : undefined;
+	const props = root?.properties;
+	// Fall back to the JSON editor when there is no schema, or any field is a shape the generic
+	// form can't express (a non-enum union, a $ref). Partial rendering would be worse than none:
+	// a field silently missing from the form is a setting the operator cannot change.
+	const canRender = props !== undefined && Object.values(props).every(renderable);
+
+	if (!canRender) {
+		return (
+			<div className="space-y-3">
+				<p className="text-xs text-muted-foreground">
+					{m.library_source_settings_json_hint()}
+				</p>
+				<textarea
+					className="h-64 w-full rounded-md border bg-background p-2 font-mono text-xs"
+					value={raw}
+					onChange={(e) => onRaw(e.target.value)}
+					spellCheck={false}
+				/>
+				<Button
+					disabled={saving}
+					onClick={() => {
+						try {
+							onSave(JSON.parse(raw) as JsonObject);
+						} catch (e) {
+							toast.error(
+								m.library_source_settings_failed({ issue: String(e) }),
+							);
+						}
+					}}
+				>
+					{m.library_source_settings_save()}
+				</Button>
+			</div>
+		);
+	}
+
+	return (
+		<div className="space-y-4">
+			{Object.entries(props).map(([key, rawNode]) => (
+				<Field
+					key={key}
+					name={key}
+					node={flatten(rawNode)}
+					value={draft[key]}
+					onChange={(v) => setDraft((d) => ({ ...d, [key]: v }))}
+				/>
+			))}
+			<Button disabled={saving} onClick={() => onSave(draft)}>
+				{m.library_source_settings_save()}
+			</Button>
+		</div>
+	);
+};
+
+/** One schema field. `undefined` in the draft means "unset" — the file keeps its default out. */
+const Field: FC<{
+	name: string;
+	node: JsonSchemaNode;
+	value: unknown;
+	onChange: (v: unknown) => void;
+}> = ({ name, node, value, onChange }) => {
+	const label = node.title ?? name;
+	const id = `cfg-${name}`;
+
+	if (node.type === "object" && node.properties) {
+		const nested = (value ?? {}) as JsonObject;
+		return (
+			<fieldset className="space-y-3 rounded-lg border p-3">
+				<legend className="px-1 text-sm font-medium">{label}</legend>
+				{Object.entries(node.properties).map(([k, n]) => (
+					<Field
+						key={k}
+						name={`${name}.${k}`}
+						node={flatten(n)}
+						value={nested[k]}
+						onChange={(v) => onChange({ ...nested, [k]: v })}
+					/>
+				))}
+			</fieldset>
+		);
+	}
+
+	if (node.enum) {
+		return (
+			<div className="space-y-1">
+				<Label htmlFor={id}>{label}</Label>
+				<select
+					id={id}
+					className="h-9 w-full rounded-md border bg-background px-2 text-sm"
+					value={String(value ?? node.default ?? node.enum[0])}
+					onChange={(e) => onChange(e.target.value)}
+				>
+					{node.enum.map((opt) => (
+						<option key={opt} value={opt}>
+							{opt}
+						</option>
+					))}
+				</select>
+				{node.description && (
+					<p className="text-xs text-muted-foreground">{node.description}</p>
+				)}
+			</div>
+		);
+	}
+
+	if (node.type === "boolean") {
+		const checked = (value ?? node.default ?? false) as boolean;
+		return (
+			<div className="space-y-1">
+				<div className="flex items-center gap-2">
+					<input
+						id={id}
+						type="checkbox"
+						checked={checked}
+						onChange={(e) => onChange(e.target.checked)}
+					/>
+					<Label htmlFor={id}>{label}</Label>
+				</div>
+				{node.description && (
+					<p className="text-xs text-muted-foreground">{node.description}</p>
+				)}
+			</div>
+		);
+	}
+
+	if (node.type === "array") {
+		// One absolute path per line — the shape every "extra library folders" setting wants.
+		const list = (value ?? node.default ?? []) as string[];
+		return (
+			<div className="space-y-1">
+				<Label htmlFor={id}>{label}</Label>
+				<textarea
+					id={id}
+					className="h-24 w-full rounded-md border bg-background p-2 font-mono text-xs"
+					value={list.join("\n")}
+					onChange={(e) =>
+						onChange(
+							e.target.value
+								.split("\n")
+								.map((s) => s.trim())
+								.filter((s) => s !== ""),
+						)
+					}
+				/>
+				{node.description && (
+					<p className="text-xs text-muted-foreground">{node.description}</p>
+				)}
+			</div>
+		);
+	}
+
+	const numeric = node.type === "number" || node.type === "integer";
+	return (
+		<div className="space-y-1">
+			<Label htmlFor={id}>{label}</Label>
+			<Input
+				id={id}
+				type={numeric ? "number" : "text"}
+				value={String(value ?? "")}
+				placeholder={node.default != null ? String(node.default) : undefined}
+				onChange={(e) => {
+					const v = e.target.value;
+					// An emptied field means "unset", which is NOT the same as zero or "" — it is what
+					// keeps the operator's file free of a value they never chose.
+					if (v === "") return onChange(undefined);
+					onChange(numeric ? Number(v) : v);
+				}}
+			/>
+			{node.description && (
+				<p className="text-xs text-muted-foreground">{node.description}</p>
+			)}
+		</div>
+	);
+};

web/src/sections/Library/SourceToggles.tsx

@@ -1,85 +0,0 @@
-import { useQueryClient } from "@tanstack/react-query";
-import { toast } from "@unom/ui/toast";
-import { Check } from "lucide-react";
-import type { FC } from "react";
-import {
-	getGetLibraryQueryKey,
-	getListLibraryScannersQueryKey,
-	useListLibraryScanners,
-	useSetLibraryScanner,
-} from "@/api/gen/library/library";
-import type { ScannerInfo } from "@/api/gen/model/scannerInfo";
-import { Button } from "@/components/ui/button";
-import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
-import { m } from "@/paraglide/messages";
-
-/**
- * Container: the game-source (library scanner) toggles — owns the scanner query and the toggle
- * mutation. The host only reports the scanners its platform actually has (Steam everywhere,
- * Lutris/Heroic on Linux, Epic/GOG/Xbox on Windows), so whatever arrives is renderable as-is.
- * Rendered only once the list is loaded: this is a secondary control, and when the API is down
- * the grid's own QueryState already tells the story — no second error banner.
- */
-export const SourceTogglesSection: FC = () => {
-	const qc = useQueryClient();
-	const scanners = useListLibraryScanners();
-	const toggle = useSetLibraryScanner();
-
-	const onToggle = async (scanner: ScannerInfo) => {
-		try {
-			// The PUT answers with the full updated list — seed the query cache with it directly,
-			// then refetch the library so the grid reflects the new source set.
-			const list = await toggle.mutateAsync({
-				id: scanner.id,
-				data: { enabled: !scanner.enabled },
-			});
-			qc.setQueryData(getListLibraryScannersQueryKey(), list);
-			await qc.invalidateQueries({ queryKey: getGetLibraryQueryKey() });
-		} catch {
-			toast.error(m.library_sources_failed());
-		}
-	};
-
-	if (!scanners.data) return null;
-	return (
-		<SourceToggles
-			scanners={scanners.data}
-			busyId={toggle.isPending ? (toggle.variables?.id ?? null) : null}
-			onToggle={onToggle}
-		/>
-	);
-};
-
-/** The sources card: one pressed/unpressed chip per scanner (pressed = the host scans it). */
-export const SourceToggles: FC<{
-	scanners: ScannerInfo[];
-	/** Scanner id whose toggle is in flight, or null — only that chip disables. */
-	busyId: string | null;
-	onToggle: (scanner: ScannerInfo) => void;
-}> = ({ scanners, busyId, onToggle }) => (
-	<Card>
-		<CardHeader className="pb-3">
-			<CardTitle className="text-base">{m.library_sources_title()}</CardTitle>
-		</CardHeader>
-		<CardContent className="space-y-3">
-			<div className="flex flex-wrap gap-2">
-				{scanners.map((scanner) => (
-					<Button
-						key={scanner.id}
-						size="sm"
-						variant={scanner.enabled ? "default" : "outline"}
-						aria-pressed={scanner.enabled}
-						disabled={busyId === scanner.id}
-						onClick={() => onToggle(scanner)}
-					>
-						{scanner.enabled && <Check className="size-4" />}
-						{scanner.label}
-					</Button>
-				))}
-			</div>
-			<p className="max-w-prose text-xs text-muted-foreground">
-				{m.library_sources_help()}
-			</p>
-		</CardContent>
-	</Card>
-);

web/src/sections/Library/Sources.tsx

@@ -0,0 +1,361 @@
+import { useQueryClient } from "@tanstack/react-query";
+import { toast } from "@unom/ui/toast";
+import { Check, Download, Settings2, Trash2 } from "lucide-react";
+import { type FC, useState } from "react";
+import {
+	getGetLibraryQueryKey,
+	getListLibraryScannersQueryKey,
+	useDeleteProviderEntries,
+	useListLibraryScanners,
+	useSetLibraryScanner,
+} from "@/api/gen/library/library";
+import type { ScannerInfo } from "@/api/gen/model/scannerInfo";
+import { libraryPlugins, usePlugins } from "@/api/plugins";
+import {
+	type StoreEntry,
+	useInstallPlugin,
+	useStoreCatalog,
+} from "@/api/store";
+import { Badge } from "@/components/ui/badge";
+import { Button } from "@/components/ui/button";
+import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
+import { apiErrorMessage } from "@/lib/errors";
+import { m } from "@/paraglide/messages";
+import { SourceSettingsDialog } from "./SourceSettings";
+
+/**
+ * **Game sources** — the single surface for "where do my games come from", merging what used to be
+ * two cards (the scanner toggles and the "synced by plugins" list).
+ *
+ * They were split because they were different things: scanners were compiled into the host and
+ * plugins were an afterthought. After the extraction they are the *same* thing — the host reports
+ * one list of sources whose ids match whether they came from a built-in scanner or the plugin that
+ * replaced it — so one surface is both simpler and the only honest presentation (design D6).
+ *
+ * Deliberately kept under the existing "Game sources" label rather than a new "Plugins" heading:
+ * `store_title` and `nav_plugins` are both already "Plugins", and a third would be worse than the
+ * merge is good.
+ */
+export const SourcesSection: FC<{
+	/** The provider currently filtered to in the grid, or null for "everything". */
+	activeFilter: string | null;
+	onFilter: (provider: string | null) => void;
+}> = ({ activeFilter, onFilter }) => {
+	const qc = useQueryClient();
+	const scanners = useListLibraryScanners();
+	const toggle = useSetLibraryScanner();
+	const purge = useDeleteProviderEntries();
+	const plugins = usePlugins();
+	const catalog = useStoreCatalog();
+	const install = useInstallPlugin();
+	const [settingsFor, setSettingsFor] = useState<ScannerInfo | null>(null);
+
+	const onToggle = async (source: ScannerInfo) => {
+		try {
+			// The PUT answers with the full updated list — seed the query cache with it directly,
+			// then refetch the library so the grid reflects the new source set.
+			const list = await toggle.mutateAsync({
+				id: source.id,
+				data: { enabled: !source.enabled },
+			});
+			qc.setQueryData(getListLibraryScannersQueryKey(), list);
+			await qc.invalidateQueries({ queryKey: getGetLibraryQueryKey() });
+		} catch {
+			toast.error(m.library_sources_failed());
+		}
+	};
+
+	const onPurge = async (source: ScannerInfo) => {
+		const provider = source.provider ?? source.id;
+		const count = source.entries ?? 0;
+		if (!confirm(m.library_provider_purge_confirm({ provider, count }))) return;
+		try {
+			await purge.mutateAsync({ provider });
+			qc.invalidateQueries({ queryKey: getGetLibraryQueryKey() });
+			qc.invalidateQueries({ queryKey: getListLibraryScannersQueryKey() });
+			if (activeFilter === provider) onFilter(null);
+			toast.success(m.library_provider_purged({ provider }));
+		} catch (e) {
+			toast.error(apiErrorMessage(e) ?? m.library_provider_purge_failed());
+		}
+	};
+
+	const onInstall = async (entry: StoreEntry) => {
+		try {
+			// Install by (source, id) — the catalogued, integrity-pinned path. The raw-spec form is
+			// for unverified installs and must never be reachable from a one-click rail.
+			await install.mutateAsync({ source: entry.source, id: entry.id });
+			toast.success(m.library_source_installing({ title: entry.title }));
+		} catch (e) {
+			toast.error(apiErrorMessage(e) ?? m.library_source_install_failed());
+		}
+	};
+
+	// This is a secondary control: when the API is down the grid's own QueryState already tells the
+	// story, so render nothing rather than a second error banner.
+	if (!scanners.data) return null;
+
+	// Catalog rows that are library sources and not already installed — the "Add a source" rail.
+	const installedPkgs = new Set(
+		(catalog.data?.plugins ?? [])
+			.filter((p) => p.installed_version)
+			.map((p) => p.pkg),
+	);
+	const available = (catalog.data?.plugins ?? []).filter(
+		(p) => p.categories?.includes("library") && !installedPkgs.has(p.pkg),
+	);
+	const running = new Set(libraryPlugins(plugins.data).map((p) => p.id));
+
+	// The bridge-release nudge (design D9): a built-in scanner still doing the work, with its
+	// replacement plugin sitting uninstalled in the catalog. One click per scanner, and NEVER a
+	// silent auto-install — installing code stays an explicit operator act.
+	const migratable = scanners.data
+		.filter((s) => s.origin === "builtin" && s.enabled)
+		.map((s) => ({
+			source: s,
+			entry: available.find((p) => p.id === s.id && p.compatible),
+		}))
+		.filter((r): r is { source: ScannerInfo; entry: StoreEntry } => !!r.entry);
+
+	return (
+		<>
+			{migratable.length > 0 && (
+				<MigrationBanner
+					rows={migratable}
+					busy={catalog.data?.busy === true || install.isPending}
+					onInstall={onInstall}
+				/>
+			)}
+			<SourcesCard
+				sources={scanners.data}
+				available={available}
+				running={running}
+				busyId={toggle.isPending ? (toggle.variables?.id ?? null) : null}
+				installBusy={catalog.data?.busy === true || install.isPending}
+				activeFilter={activeFilter}
+				onToggle={onToggle}
+				onFilter={onFilter}
+				onSettings={setSettingsFor}
+				onPurge={onPurge}
+				onInstall={onInstall}
+			/>
+			{settingsFor && (
+				<SourceSettingsDialog
+					source={settingsFor}
+					onClose={() => setSettingsFor(null)}
+				/>
+			)}
+		</>
+	);
+};
+
+/**
+ * "Game sources are moving to plugins" — shown only while a built-in scanner is still doing a job a
+ * catalogued plugin could take over.
+ *
+ * One button per scanner rather than a single "migrate everything": installing a plugin is an
+ * explicit operator act under the store's consent model, and per-scanner is also what makes it safe
+ * to repeat — the claim suppresses the built-in idempotently (design D2), so a half-finished
+ * migration is a valid state rather than a mess.
+ */
+export const MigrationBanner: FC<{
+	rows: ReadonlyArray<{ source: ScannerInfo; entry: StoreEntry }>;
+	busy: boolean;
+	onInstall: (entry: StoreEntry) => void;
+}> = ({ rows, busy, onInstall }) => (
+	<Card>
+		<CardHeader className="pb-3">
+			<CardTitle className="text-base">{m.library_migrate_title()}</CardTitle>
+		</CardHeader>
+		<CardContent className="space-y-3">
+			<p className="max-w-prose text-sm text-muted-foreground">
+				{m.library_migrate_help()}
+			</p>
+			<div className="flex flex-wrap gap-2">
+				{rows.map(({ source, entry }) => (
+					<Button
+						key={source.id}
+						size="sm"
+						variant="outline"
+						disabled={busy}
+						onClick={() => onInstall(entry)}
+					>
+						<Download className="size-4" />
+						{m.library_migrate_install({ source: source.label })}
+					</Button>
+				))}
+			</div>
+		</CardContent>
+	</Card>
+);
+
+/** The sources card itself — presentational, so Storybook can drive every state. */
+export const SourcesCard: FC<{
+	sources: ScannerInfo[];
+	/** Catalog rows offering a library source that isn't installed yet. */
+	available: StoreEntry[];
+	/** Ids of library plugins whose lease is currently live. */
+	running: Set<string>;
+	/** Source id whose toggle is in flight, or null — only that row disables. */
+	busyId: string | null;
+	installBusy: boolean;
+	activeFilter: string | null;
+	onToggle: (source: ScannerInfo) => void;
+	onFilter: (provider: string | null) => void;
+	onSettings: (source: ScannerInfo) => void;
+	onPurge: (source: ScannerInfo) => void;
+	onInstall: (entry: StoreEntry) => void;
+}> = ({
+	sources,
+	available,
+	running,
+	busyId,
+	installBusy,
+	activeFilter,
+	onToggle,
+	onFilter,
+	onSettings,
+	onPurge,
+	onInstall,
+}) => (
+	<Card>
+		<CardHeader className="pb-3">
+			<CardTitle className="text-base">{m.library_sources_title()}</CardTitle>
+		</CardHeader>
+		<CardContent className="space-y-4">
+			<div className="flex flex-col gap-2">
+				{sources.map((source) => (
+					<SourceRow
+						key={source.id}
+						source={source}
+						running={running.has(source.id)}
+						busy={busyId === source.id}
+						filtered={
+							activeFilter !== null &&
+							activeFilter === (source.provider ?? source.id)
+						}
+						onToggle={() => onToggle(source)}
+						onFilter={() => {
+							const p = source.provider ?? source.id;
+							onFilter(activeFilter === p ? null : p);
+						}}
+						onSettings={() => onSettings(source)}
+						onPurge={() => onPurge(source)}
+					/>
+				))}
+			</div>
+			<p className="max-w-prose text-xs text-muted-foreground">
+				{m.library_sources_help()}
+			</p>
+
+			{available.length > 0 && (
+				<div className="space-y-2 border-t pt-4">
+					<p className="text-sm font-medium">{m.library_add_source()}</p>
+					<div className="flex flex-wrap gap-2">
+						{available.map((entry) => (
+							<Button
+								key={entry.pkg}
+								size="sm"
+								variant="outline"
+								disabled={!entry.compatible || installBusy}
+								title={entry.incompatible_reason ?? entry.description}
+								onClick={() => onInstall(entry)}
+							>
+								<Download className="size-4" />
+								{entry.title}
+								{/* `detected` is tri-state: only badge a POSITIVE probe. An entry with
+								    no probes for this platform is "unknown", and labelling that "not
+								    installed" would be a lie. */}
+								{entry.detected === true && (
+									<Badge variant="secondary">
+										{m.library_source_detected()}
+									</Badge>
+								)}
+							</Button>
+						))}
+					</div>
+				</div>
+			)}
+		</CardContent>
+	</Card>
+);
+
+/** One source row: enable toggle, provenance, counts, and its per-source actions. */
+const SourceRow: FC<{
+	source: ScannerInfo;
+	/** The plugin backing this source is currently registered (its lease is live). */
+	running: boolean;
+	busy: boolean;
+	filtered: boolean;
+	onToggle: () => void;
+	onFilter: () => void;
+	onSettings: () => void;
+	onPurge: () => void;
+}> = ({
+	source,
+	running,
+	busy,
+	filtered,
+	onToggle,
+	onFilter,
+	onSettings,
+	onPurge,
+}) => {
+	const isPlugin = source.origin === "plugin";
+	return (
+		<div className="flex flex-wrap items-center gap-3 rounded-lg border p-3">
+			<Button
+				size="sm"
+				variant={source.enabled ? "default" : "outline"}
+				aria-pressed={source.enabled}
+				disabled={busy}
+				onClick={onToggle}
+			>
+				{source.enabled && <Check className="size-4" />}
+				{source.label}
+			</Button>
+			{isPlugin && (
+				<Badge variant={running ? "secondary" : "outline"}>
+					{running ? m.library_source_running() : m.library_source_stopped()}
+				</Badge>
+			)}
+			{source.entries != null && (
+				<Badge variant="secondary">
+					{m.library_provider_count({ count: source.entries })}
+				</Badge>
+			)}
+			<div className="ml-auto flex gap-2">
+				{isPlugin && (
+					<>
+						<Button
+							size="sm"
+							variant={filtered ? "default" : "outline"}
+							aria-pressed={filtered}
+							onClick={onFilter}
+						>
+							{filtered
+								? m.library_provider_show_all()
+								: m.library_provider_filter()}
+						</Button>
+						<Button
+							size="sm"
+							variant="outline"
+							aria-label={m.library_source_settings()}
+							onClick={onSettings}
+						>
+							<Settings2 className="size-4" />
+						</Button>
+						<Button
+							size="sm"
+							variant="outline"
+							aria-label={m.library_provider_purge()}
+							onClick={onPurge}
+						>
+							<Trash2 className="size-4 text-destructive" />
+						</Button>
+					</>
+				)}
+			</div>
+		</div>
+	);
+};

web/src/sections/Library/index.tsx

@@ -7,8 +7,7 @@ import { useLocale } from "@/lib/i18n";
 import { m } from "@/paraglide/messages";
 import { type FormTarget, GameFormSection } from "./GameForm";
 import { LibraryGridSection } from "./LibraryGrid";
-import { ProvidersCard } from "./Providers";
-import { SourceTogglesSection } from "./SourceToggles";
+import { SourcesSection } from "./Sources";
 
 // Library = an OVERVIEW grid + a SEPARATE add/edit form, deliberately split into their own files
 // (LibraryGrid / GameForm) so the two concerns never share a component. This container owns only the
@@ -44,11 +43,8 @@ export const SectionLibrary: FC = () => {
 					/>
 				)}
 
-				<SourceTogglesSection />
-
-				<ProvidersCard
-					entries={entries}
-					active={providerFilter}
+				<SourcesSection
+					activeFilter={providerFilter}
 					onFilter={setProviderFilter}
 				/>
 

web/src/stories/Library.stories.tsx

@@ -1,7 +1,7 @@
 import type { Meta, StoryObj } from "@storybook/react-vite";
 import { GameForm } from "@/sections/Library/GameForm";
 import { LibraryGrid } from "@/sections/Library/LibraryGrid";
-import { SourceToggles } from "@/sections/Library/SourceToggles";
+import { MigrationBanner, SourcesCard } from "@/sections/Library/Sources";
 import { library } from "./lib/fixtures";
 
 const noop = () => {};
@@ -16,6 +16,7 @@ const emptyForm = {
 	// The console-password confirmation the form requires alongside a launch command; empty here
 	// because the story renders the untouched add form, which has no command yet.
 	password: "",
+	isLauncher: false,
 	platform: "",
 	description: "",
 	developer: "",
@@ -48,6 +49,31 @@ export const Populated: Story = {
 	),
 };
 
+/** Launcher entries (design D4) get their own rail above the grid. */
+export const WithLaunchers: Story = {
+	render: () => (
+		<LibraryGrid
+			library={{
+				data: [
+					{
+						id: "steam:bigpicture",
+						store: "steam",
+						title: "Steam Big Picture",
+						art: { portrait: null, hero: null, logo: null, header: null },
+						role: "launcher",
+						launch: { kind: "steam_ui", value: "bigpicture" },
+					},
+					...library,
+				],
+				...idle,
+			}}
+			onEdit={noop}
+			onDelete={noop}
+			deletingId={null}
+		/>
+	),
+};
+
 export const Empty: Story = {
 	render: () => (
 		<LibraryGrid
@@ -59,17 +85,148 @@ export const Empty: Story = {
 	),
 };
 
+/** A catalog row for the "Add a source" rail — only the fields the card actually reads. */
+const catalogEntry = (
+	over: Partial<Parameters<typeof SourcesCard>[0]["available"][number]>,
+) =>
+	({
+		id: "steam",
+		pkg: "@punktfunk/plugin-steam",
+		title: "Steam",
+		description: "Steam library scanner",
+		author: "unom",
+		version: "0.1.0",
+		source: "unom",
+		tier: "verified",
+		platforms: [],
+		compatible: true,
+		update_available: false,
+		categories: ["library"],
+		...over,
+	}) as Parameters<typeof SourcesCard>[0]["available"][number];
+
+const sourcesArgs = {
+	available: [],
+	running: new Set<string>(),
+	busyId: null,
+	installBusy: false,
+	activeFilter: null,
+	onToggle: noop,
+	onFilter: noop,
+	onSettings: noop,
+	onPurge: noop,
+	onInstall: noop,
+};
+
+/** The bridge-release shape: built-in scanners only, one turned off. */
 export const Sources: Story = {
 	render: () => (
-		<SourceToggles
-			// A Linux host's scanner set, one turned off — the widest built-in list.
-			scanners={[
-				{ id: "steam", label: "Steam", enabled: true },
-				{ id: "lutris", label: "Lutris", enabled: false },
-				{ id: "heroic", label: "Heroic (Epic / GOG / Amazon)", enabled: true },
+		<SourcesCard
+			{...sourcesArgs}
+			sources={[
+				{ id: "steam", label: "Steam", enabled: true, origin: "builtin" },
+				{ id: "lutris", label: "Lutris", enabled: false, origin: "builtin" },
+				{
+					id: "heroic",
+					label: "Heroic (Epic / GOG / Amazon)",
+					enabled: true,
+					origin: "builtin",
+				},
 			]}
-			busyId={null}
-			onToggle={noop}
+		/>
+	),
+};
+
+/** Mid-migration: a claimed plugin source beside the remaining built-ins, one plugin stopped. */
+export const SourcesWithPlugins: Story = {
+	render: () => (
+		<SourcesCard
+			{...sourcesArgs}
+			sources={[
+				{
+					id: "steam",
+					label: "Steam",
+					enabled: true,
+					origin: "plugin",
+					provider: "steam",
+					entries: 214,
+				},
+				{
+					id: "lutris",
+					label: "Lutris",
+					enabled: false,
+					origin: "plugin",
+					provider: "lutris",
+					entries: 12,
+				},
+				{
+					id: "heroic",
+					label: "Heroic (Epic / GOG / Amazon)",
+					enabled: true,
+					origin: "builtin",
+				},
+			]}
+			running={new Set(["steam"])}
+			available={[
+				catalogEntry({ pkg: "@punktfunk/plugin-heroic", title: "Heroic" }),
+			]}
+		/>
+	),
+};
+
+/** A fresh host after extraction: nothing installed, two launchers detected on this box. */
+export const SourcesEmptyWithDetected: Story = {
+	render: () => (
+		<SourcesCard
+			{...sourcesArgs}
+			sources={[]}
+			available={[
+				catalogEntry({ detected: true }),
+				catalogEntry({
+					pkg: "@punktfunk/plugin-lutris",
+					title: "Lutris",
+					detected: true,
+				}),
+				catalogEntry({
+					pkg: "@punktfunk/plugin-heroic",
+					title: "Heroic",
+					detected: false,
+				}),
+			]}
+		/>
+	),
+};
+
+/** The bridge-release nudge — one button per still-built-in scanner, never an auto-install. */
+export const Migration: Story = {
+	render: () => (
+		<MigrationBanner
+			rows={[
+				{
+					source: {
+						id: "steam",
+						label: "Steam",
+						enabled: true,
+						origin: "builtin",
+					},
+					entry: catalogEntry({}),
+				},
+				{
+					source: {
+						id: "lutris",
+						label: "Lutris",
+						enabled: true,
+						origin: "builtin",
+					},
+					entry: catalogEntry({
+						pkg: "@punktfunk/plugin-lutris",
+						id: "lutris",
+						title: "Lutris",
+					}),
+				},
+			]}
+			busy={false}
+			onInstall={noop}
 		/>
 	),
 };