ci(android): canary also feeds Play closed testing (alpha)

Closed testing went dry on 2026-08-01 when tags started publishing
straight to production instead of alpha — its testers have been pinned
to the last pre-access build since. Canaries now assign the same
versionCode to beta (open) AND alpha (closed) via play-upload.py's new
repeatable --also-track flag: both PUTs share one Play edit, so one
commit and one review cover both tracks and they can never disagree
about which canary is current. Tags still go to production only.

.gitea/workflows/android-promote.yml

@@ -6,7 +6,7 @@
 # android.yml would mean an `if:` on all ten of its build steps.
 #
 # What it is for:
-#   * promote a tested build up a track (alpha -> production)
+#   * promote a tested build up a track (beta -> production)
 #   * roll production back by re-pointing it at an older versionCode (to_track=production,
 #     version_code=<the good one>, from_track blank)
 #   * halt a rollout (status=halted)
@@ -36,7 +36,7 @@ on:
       from_track:
         description: 'track to verify it is on, then clear (blank = touch nothing else)'
         required: false
-        default: 'alpha'
+        default: 'beta'
       notes_tag:
         description: "tag whose docs/releases/whatsnew/<tag>.txt to attach, e.g. v0.23.0 (blank = none)"
         required: false

.gitea/workflows/android.yml

@@ -36,8 +36,13 @@ on:
       - '.gitea/workflows/android.yml'
     # Single project version: a `vX.Y.Z` tag is THE release (publishes to Play `production` at
     # 100% + attaches the .aab/.apk to the unified Gitea Release). A main push is canary
-    # (Play `internal`). Production access was granted 2026-08-01; before that a tag could only
-    # reach `alpha` and someone had to promote it by hand in the Console.
+    # (Play `beta` = open testing: public opt-in, no tester list — but unlike the previous
+    # `internal` target, every canary now passes Google review before testers see it, so a
+    # canary lands in hours/days, not minutes). The same canary versionCode is also assigned
+    # to `alpha` (closed testing) in the same Play edit, so the pre-production-access closed
+    # testers keep receiving builds without re-opting-in. Production access was granted
+    # 2026-08-01; before that a tag could only reach `alpha` and someone had to promote it
+    # by hand in the Console.
     tags: ['v*']
   pull_request:
     paths:
@@ -94,8 +99,9 @@ jobs:
       # store listing. Failing here also means a missing file cannot leave a half-published
       # release: nothing is built, nothing is attached to the Gitea release, nothing reaches Play.
       #
-      # Canary is exempt on purpose: it has no curated notes, and Play reusing text for internal
-      # testers costs nothing.
+      # Canary is exempt on purpose: it has no curated notes. Open-testing users therefore see
+      # the previous release's text on a canary — cosmetic, and cheaper than gating every main
+      # push on a notes file.
       - name: Play release notes gate (tags only)
         if: startsWith(github.ref, 'refs/tags/v')
         run: |
@@ -226,11 +232,12 @@ jobs:
         run: |
           eval "$(bash scripts/ci/pf-version.sh)"   # -> PF_BASE (one minor ahead of the latest stable tag)
           case "$GITHUB_REF" in
-            refs/tags/v*) VN="${GITHUB_REF_NAME#v}"; TRACK="production" ;;
-            *)            VN="${PF_BASE}-ci${GITHUB_RUN_NUMBER}"; TRACK="internal" ;;
+            refs/tags/v*) VN="${GITHUB_REF_NAME#v}"; TRACK="production"; ALSO="" ;;
+            *)            VN="${PF_BASE}-ci${GITHUB_RUN_NUMBER}"; TRACK="beta"; ALSO="alpha" ;;
           esac
           echo "VERSION_NAME=$VN" >> "$GITHUB_ENV"
           echo "PLAY_TRACK=$TRACK" >> "$GITHUB_ENV"
+          echo "PLAY_ALSO_TRACK=$ALSO" >> "$GITHUB_ENV"
           # Play's own "What's new" (500-char cap, its own file — the vX.Y.Z.md body is ~34 KB).
           # On a tag the gate step above already proved this exists, so the else branch is only
           # ever the canary path. See docs/releases/README.md.
@@ -240,7 +247,7 @@ jobs:
           else
             echo "no Play release notes at $NOTES (canary — Play keeps the previous text)"
           fi
-          echo "android version $VN -> Play track '$TRACK'"
+          echo "android version $VN -> Play track '$TRACK'${ALSO:+ (+ '$ALSO')}"
 
       - name: Build Release (signed AAB + universal APK)
         if: github.event_name == 'push' && (github.ref == 'refs/heads/main' || startsWith(github.ref, 'refs/tags/v'))
@@ -312,7 +319,8 @@ jobs:
       # Direct Publishing-API upload instead of r0adkll/upload-google-play — that action hides the
       # real API error behind "Unknown error occurred."; this prints it. stdlib + openssl only (no
       # pip), reuses SERVICE_ACCOUNT_JSON (raw JSON or base64), auto-handles changesNotSentForReview.
-      # Track: canary main -> `internal`; a vX.Y.Z release -> `production` at 100% (`completed`).
+      # Track: canary main -> `beta` (open testing) + the same versionCode on `alpha` (closed
+      # testing) in the same Play edit; a vX.Y.Z release -> `production` at 100% (`completed`).
       #
       # A tag therefore ships to real users with no further click. Two things keep that honest:
       # the tag is only pushed once every platform is green, and Play reviews each production
@@ -324,9 +332,10 @@ jobs:
         env:
           SERVICE_ACCOUNT_JSON: ${{ secrets.SERVICE_ACCOUNT_JSON }}
         run: |
-          echo "uploading to Play track '$PLAY_TRACK'"
+          echo "uploading to Play track '$PLAY_TRACK'${PLAY_ALSO_TRACK:+ (+ '$PLAY_ALSO_TRACK')}"
           set -- --package io.unom.punktfunk \
                  --aab clients/android/app/build/outputs/bundle/release/app-release.aab \
                  --track "$PLAY_TRACK" --status completed
+          if [ -n "${PLAY_ALSO_TRACK:-}" ]; then set -- "$@" --also-track "$PLAY_ALSO_TRACK"; fi
           if [ -n "${PLAY_NOTES:-}" ]; then set -- "$@" --release-notes-file "$PLAY_NOTES"; fi
           python3 clients/android/ci/play-upload.py "$@"

CHANGELOG.md

@@ -642,6 +642,38 @@ CONTRIBUTING.md) and nothing in CI enforces it.** Three drifts in two release cy
 argument for gating it; until something does, **treat the copy as part of regenerating, not as a
 follow-up.**
 
+### Linux — the data-plane threads finally get the priority they ask for (⚠ packager-visible)
+
+**On every Linux host to date, `pf_frame::thread_qos`'s per-thread renice was a silent no-op** —
+it needs CAP_SYS_NICE or a raised RLIMIT_NICE, no packaging channel granted either, and the host
+binary can never carry a file capability (KWin identification, the 0.26.0-1 incident). So the
+capture/encode and send threads ran at nice 0, and a CPU-saturating burst on the host — a fresh
+game launch's shader-compile storm is the canonical one — descheduled them at will. A 2026-08-14
+field log showed the result end to end: 5 ms audio datagrams leaving late enough to stutter, the
+client's delay signal rising, and ABR cutting a gigabit-Ethernet session to its 5 Mbps floor with
+zero packet loss — while the box carried 708 Mbps cleanly minutes later, once the storm passed.
+
+**The renice now falls back to RealtimeKit** (`MakeThreadHighPriorityWithPID`, one blocking
+system-bus call per boosted thread) — the same unprivileged broker PipeWire clients use, present
+on effectively every desktop install. No capability enters the host's permitted set, so KWin
+identification is untouched. Boxes with neither rtkit nor the new limit keep today's best-effort
+no-op, one debug line per thread.
+
+**The audio plane is boosted at all for the first time.** The 5 ms Opus capture→encode→send loop,
+the PipeWire capture mainloop thread (its `process` callbacks run there — PipeWire's own
+`module-rt` only covers data loops we don't use), and the pad-audio streamer now take the same
+boost the video threads always asked for. The audio loop is `critical`: a scheduling stall there
+is directly audible where a late video frame is one presentation slip.
+
+⚠ **Packagers: a new `user@.service.d` drop-in.** rpm/deb/Arch (and the Bazzite sysext, via the
+RPM) now ship `packaging/linux/50-punktfunk-nice.conf` →
+`/usr/lib/systemd/system/user@.service.d/50-punktfunk-nice.conf` (`LimitNICE=-15`), so the direct
+`setpriority()` also works where rtkit isn't running. It raises a session *limit*, from the next
+login — nothing is reprioritized by itself. The NixOS module instead sets
+`security.rtkit.enable = lib.mkDefault true` (rtkit is not a given there). It remains true that
+**no channel may ever grant the host binary a file capability** — this change is the sanctioned
+route to the same end.
+
 ---
 
 ## v0.28.0

Cargo.lock

@@ -3115,6 +3115,7 @@ dependencies = [
  "punktfunk-core",
  "tracing",
  "windows 0.62.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "zbus",
 ]
 
 [[package]]

clients/android/README.md

@@ -22,7 +22,8 @@ Google TV, budget Amlogic boxes) that otherwise reject a 64-bit-only build as "n
 
 ## Get it
 
-Published to **Google Play (Internal Testing)** — join the beta via the
+Published to **Google Play (Open Testing)** — join via the
+[public opt-in link](https://play.google.com/apps/testing/io.unom.punktfunk) or the
 [Discord](https://discord.gg/kaPNvzMuGU). Per-device setup and pairing:
 **[docs.punktfunk.unom.io/docs/install-client](https://docs.punktfunk.unom.io/docs/install-client)**.
 

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

@@ -243,6 +243,15 @@ fun ConnectScreen(
                     knownHostStore.learnOs(dh.host, dh.port, dh.os)
                     any = true
                 }
+                // And the mgmt port, so a host that moved off 47990 keeps its library once this
+                // device can no longer see the advert (VPN, routed subnet, multicast-dead Wi-Fi).
+                val mgmt = dh.mgmtPort
+                if (mgmt != null &&
+                    knownHostStore.get(dh.host, dh.port)?.let { it.mgmtPort != mgmt } == true
+                ) {
+                    knownHostStore.learnMgmtPort(dh.host, dh.port, mgmt)
+                    any = true
+                }
             }
             any
         }
@@ -313,13 +322,24 @@ fun ConnectScreen(
     // What the stream screen is handed: the settings this connect actually used, plus the HOST's
     // clipboard decision (a property of the record, not a global). A host we never saved — a
     // connect that failed to pin — falls back to the on default the setting always had.
-    fun session(handle: Long, record: KnownHost?, profile: StreamProfile?) = ActiveSession(
-        handle,
-        settings.effectiveFor(profile),
-        clipboardSync = record?.clipboardSync ?: true,
-        profileName = profile?.name,
-        hostId = record?.id,
-    )
+    fun session(handle: Long, record: KnownHost?, profile: StreamProfile?): ActiveSession {
+        // The session's own Welcome carries where this host serves its library. Save it now: this
+        // is the only source that does not need an mDNS advert, so it is what makes a host that
+        // moved off 47990 browsable over a VPN or when it was added by address. 0 = not
+        // advertised, and learnMgmtPort ignores it.
+        if (record != null) {
+            NativeBridge.nativeHostMgmtPort(handle).takeIf { it > 0 }?.let {
+                knownHostStore.learnMgmtPort(record.address, record.port, it)
+            }
+        }
+        return ActiveSession(
+            handle,
+            settings.effectiveFor(profile),
+            clipboardSync = record?.clipboardSync ?: true,
+            profileName = profile?.name,
+            hostId = record?.id,
+        )
+    }
 
     // The actual dial (identity already ready). On a TOFU connect (pinHex null), pin the fingerprint
     // the host presented (as an unpaired known host) so the next connect goes straight through and it

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

@@ -59,7 +59,6 @@ import coil.ImageLoader
 import coil.compose.AsyncImage
 import coil.request.ImageRequest
 import io.unom.punktfunk.components.launcherIcon
-import io.unom.punktfunk.kit.library.DEFAULT_MGMT_PORT
 import io.unom.punktfunk.kit.library.GameEntry
 import io.unom.punktfunk.kit.library.LibraryClient
 import io.unom.punktfunk.kit.library.LibraryResult
@@ -120,14 +119,16 @@ fun LibraryScreen(
     }
     val streamSettings = remember(settings, profile) { settings.effectiveFor(profile) }
 
-    LaunchedEffect(host.address, host.port, host.fpHex) {
+    // Keyed on the mgmt port too: a discovery tick can learn it after this screen is composed, and
+    // the fetch must redo itself against the real port rather than stay on a stale 47990 failure.
+    LaunchedEffect(host.address, host.port, host.fpHex, host.effectiveMgmtPort) {
         state = LibState.Loading
         state = withContext(Dispatchers.IO) {
             val id = runCatching { obtainIdentity(IdentityStore(context)) }.getOrNull()
                 ?: return@withContext LibState.Message("Identity unavailable — re-pair may be required.")
             when (val res = LibraryClient.fetch(
                 address = host.address,
-                mgmtPort = DEFAULT_MGMT_PORT,
+                mgmtPort = host.effectiveMgmtPort,
                 certPem = id.certPem,
                 keyPem = id.privateKeyPem,
                 fpHex = host.fpHex,

clients/android/ci/play-upload.py

@@ -9,7 +9,8 @@ tolerates it being raw JSON *or* base64-encoded JSON.
 Usage (upload a new build):
   SERVICE_ACCOUNT_JSON='<raw-or-base64 SA key>' \
     python3 play-upload.py --package io.unom.punktfunk \
-      --aab path/to/app-release.aab --track internal --status completed [--no-commit]
+      --aab path/to/app-release.aab --track beta --also-track alpha \
+      --status completed [--no-commit]
 
 Usage (promote a build that is already on Play, no rebuild):
   python3 play-upload.py --package io.unom.punktfunk \
@@ -164,6 +165,9 @@ def main():
     ap.add_argument("--promote-from", metavar="TRACK",
                     help="with --promote: assert the code is on TRACK, then clear TRACK")
     ap.add_argument("--track", default="internal")
+    ap.add_argument("--also-track", action="append", default=[], metavar="TRACK",
+                    help="assign the same versionCode to this track too, in the same edit "
+                         "(repeatable). Canary uses it to feed open + closed testing at once.")
     ap.add_argument("--status", default="completed")
     ap.add_argument("--user-fraction", type=float,
                     help="staged rollout fraction, 0<f<1; required by --status inProgress")
@@ -183,6 +187,11 @@ def main():
         sys.exit(f"ERROR: --user-fraction must be strictly between 0 and 1 (got {a.user_fraction})")
     if a.aab and not os.path.isfile(a.aab):
         sys.exit(f"ERROR: AAB not found: {a.aab}")
+    for t in a.also_track:
+        # `--also-track <promote-from>` would assign and clear the same track in one edit;
+        # whichever PUT lands second silently wins. Refuse the ambiguity instead.
+        if t in (a.track, a.promote_from):
+            sys.exit(f"ERROR: --also-track {t} duplicates --track/--promote-from")
 
     notes = load_release_notes(a.release_notes_file, a.release_notes_language) \
         if a.release_notes_file else None
@@ -209,6 +218,11 @@ def main():
         put_track(app, edit, tok, a.track, [vc], a.status, a.user_fraction, notes)
         print(f"assigned versionCode={vc} -> track={a.track} status={a.status}"
               + (f" userFraction={a.user_fraction}" if a.user_fraction is not None else ""))
+        # Same edit, so one commit (and one Play review) covers every track the code lands on —
+        # the tracks can never disagree about which canary is current.
+        for t in a.also_track:
+            put_track(app, edit, tok, t, [vc], a.status, a.user_fraction, notes)
+            print(f"assigned versionCode={vc} -> track={t} status={a.status}")
         # Same edit as the assignment above, so the code is never active on both tracks at once.
         if a.promote_from:
             put_track(app, edit, tok, a.promote_from, [], a.status)

clients/android/kit/src/main/kotlin/io/unom/punktfunk/kit/NativeBridge.kt

@@ -477,6 +477,16 @@ object NativeBridge {
     // cross only when the host pastes (a "fetch:" event answered by nativeClipServeText). Host
     // copies arrive as "offer:" events, fetched eagerly into the system clipboard.
 
+    /**
+     * The management-API port the host reported in this session's `Welcome` — where its game
+     * library is served — or 0 if it advertised none (older host, or no management API).
+     *
+     * Persist it on the host record: unlike the mDNS `mgmt` TXT, this arrives over the connection
+     * we have already authenticated, so it is what makes a host that moved off 47990 browsable
+     * over a VPN, a routed subnet, or when it was added by address.
+     */
+    external fun nativeHostMgmtPort(handle: Long): Int
+
     /** Whether the host advertised a working shared-clipboard service (HOST_CAP_CLIPBOARD). */
     external fun nativeClipSupported(handle: Long): Boolean
 

clients/android/kit/src/main/kotlin/io/unom/punktfunk/kit/discovery/HostDiscovery.kt

@@ -19,13 +19,16 @@ data class DiscoveredHost(
     val pairingRequired: Boolean = false,
     val mac: List<String> = emptyList(), // TXT "mac" (wake-capable NIC MAC(s), for Wake-on-LAN)
     val os: String = "", // TXT "os" (OS-identity chain, e.g. "linux/fedora/bazzite"); "" on older hosts
+    // TXT "mgmt" — the management-API port the library is served on, distinct from `port` (the
+    // native QUIC plane). null on an older host / older native lib, meaning "assume 47990".
+    val mgmtPort: Int? = null,
 )
 
 /** Field separator the native browse uses inside one record (ASCII Unit Separator). */
 private const val FIELD_SEP = '\u001F'
 
 /**
- * Parse one record from [NativeBridge.nativeDiscoveryPoll] (`key␟name␟addr␟port␟fp␟pair␟mac␟os`),
+ * Parse one record from [NativeBridge.nativeDiscoveryPoll] (`key␟name␟addr␟port␟fp␟pair␟mac␟os␟mgmt`),
  * or null if it's malformed. Fields past the 6th are optional — an older native lib omits them
  * (`mac` 7th, `os` 8th). Pure — unit-tested without Android (see ParseRecordTest). The native side
  * already applied the protocol gate and address selection, so this is just field marshaling.
@@ -46,6 +49,9 @@ fun parseHostRecord(record: String): DiscoveredHost? {
         mac = if (f.size > 6) f[6].split(",").map { it.trim() }.filter { it.isNotEmpty() }
         else emptyList(),
         os = if (f.size > 7) sanitizeOsChain(f[7]) else "",
+        // 9th field, absent on an older native lib. `0` (and anything out of range) means "not
+        // advertised" → null, and the caller falls back to 47990.
+        mgmtPort = if (f.size > 8) f[8].toIntOrNull()?.takeIf { it in 1..65535 } else null,
     )
 }
 

clients/android/kit/src/main/kotlin/io/unom/punktfunk/kit/security/KnownHostStore.kt

@@ -32,6 +32,16 @@ data class KnownHost(
      * first learned (or forever, against an older host).
      */
     val os: String = "",
+    /**
+     * The host's management-API port (mDNS `mgmt` TXT), where the game library is served — NOT
+     * [port], which is the native QUIC plane. Learned while online and kept for the same reason as
+     * [mac] and [os], except this one is load-bearing: a host that moved its mgmt port off 47990
+     * (the supported way to share a machine with a Sunshine fork, whose web UI owns that port)
+     * served its library only while mDNS was reachable, because the advert was the sole place the
+     * real port ever existed. `null` until learned — resolve with [effectiveMgmtPort].
+     * Mirrors the Apple client's `StoredHost.mgmtPort` and the Rust `KnownHost.mgmt_port`.
+     */
+    val mgmtPort: Int? = null,
     /** Stable record identity — see the class doc. Minted here for a genuinely new record. */
     val id: String = newRecordId(),
     /**
@@ -54,7 +64,16 @@ data class KnownHost(
      * that no longer exist are dropped when the cards are rendered.
      */
     val pinnedProfileIds: List<String> = emptyList(),
-)
+) {
+    /**
+     * Where this host's management API actually is: the port learned from its advert, else 47990.
+     * The twin of the Apple client's `StoredHost.effectiveMgmtPort` and the Rust
+     * `KnownHost::effective_mgmt_port`. Resolve through this — the constant is the FALLBACK, not
+     * the answer.
+     */
+    val effectiveMgmtPort: Int
+        get() = mgmtPort ?: io.unom.punktfunk.kit.library.DEFAULT_MGMT_PORT
+}
 
 /**
  * Persists trusted hosts — the pinned-fingerprint store *and* the saved-hosts list — keyed by
@@ -130,6 +149,17 @@ class KnownHostStore(context: Context) {
         save(h.copy(os = os))
     }
 
+    /**
+     * Learn/refresh a saved host's management-API port from its live advert — same contract as
+     * [learnMac]. This is the one that keeps a moved mgmt port working once mDNS isn't reachable.
+     */
+    fun learnMgmtPort(address: String, port: Int, mgmtPort: Int) {
+        if (mgmtPort <= 0) return
+        val h = get(address, port) ?: return
+        if (h.mgmtPort == mgmtPort) return
+        save(h.copy(mgmtPort = mgmtPort))
+    }
+
     /** Forget [host] (the next connect re-pairs / re-TOFUs). */
     fun remove(host: KnownHost) {
         prefs.edit().remove(host.id).apply()
@@ -180,6 +210,10 @@ class KnownHostStore(context: Context) {
             paired = j.optBoolean("paired", false),
             mac = j.optString("mac", "").split(",").map { it.trim() }.filter { it.isNotEmpty() },
             os = j.optString("os", ""),
+            // 0 (or absent) = never learned. `optInt` cannot express "missing", hence the sentinel
+            // rather than a bare default — a record written before this field existed must decode
+            // to null and fall back to 47990, not to port 0.
+            mgmtPort = j.optInt("mgmt", 0).takeIf { it > 0 },
             // A record without an id can only be one this build wrote before the migration ran, or
             // a hand-edited file; minting here keeps the parse total rather than dropping a host.
             id = j.optString("id", "").ifEmpty { newRecordId() },
@@ -266,6 +300,7 @@ class KnownHostStore(context: Context) {
             .put("paired", host.paired)
             .put("mac", host.mac.joinToString(","))
             .put("os", host.os)
+            .put("mgmt", host.mgmtPort ?: 0)
             .put("clip", host.clipboardSync)
             .put("profile", host.profileId ?: "")
             .put("pins", JSONArray(host.pinnedProfileIds))

clients/android/kit/src/test/kotlin/io/unom/punktfunk/kit/discovery/ParseRecordTest.kt

@@ -47,6 +47,31 @@ class ParseRecordTest {
             rec("k", "n", "10.0.0.5", "9777", "", "optional", "", "linux/fedora/bazzite"),
         )!!
         assertEquals("linux/fedora/bazzite", h.os)
+        // A record from a native lib predating the 9th field: no mgmt port, so the caller falls
+        // back to 47990. Absent must read as "unknown", never as port 0.
+        assertNull(h.mgmtPort)
+    }
+
+    @Test
+    fun ninthFieldCarriesTheMgmtPort() {
+        // 47991, not the 47990 default — a host that MOVED its mgmt port is the whole reason this
+        // field is on the wire, and a test pinned to the default would pass against a hardcode.
+        val h = parseHostRecord(
+            rec("k", "n", "10.0.0.5", "9777", "", "optional", "", "linux/arch", "47991"),
+        )!!
+        assertEquals(47991, h.mgmtPort)
+    }
+
+    @Test
+    fun mgmtPortOutOfRangeOrUnparsableReadsAsUnknown() {
+        // Unauthenticated advert data: 0 (the "not advertised" sentinel the Rust side emits),
+        // a non-number, and an out-of-range value must all mean "assume the default" rather than
+        // produce a port the client would then fail to connect to.
+        val base = arrayOf("k", "n", "10.0.0.5", "9777", "", "optional", "", "linux/arch")
+        assertNull(parseHostRecord(rec(*base, "0"))!!.mgmtPort)
+        assertNull(parseHostRecord(rec(*base, "not-a-port"))!!.mgmtPort)
+        assertNull(parseHostRecord(rec(*base, "70000"))!!.mgmtPort)
+        assertNull(parseHostRecord(rec(*base, ""))!!.mgmtPort)
     }
 
     @Test

clients/android/native/src/discovery.rs

@@ -32,7 +32,7 @@ const PROTO: &str = "punktfunk/1";
 /// Field separator inside one serialized record (ASCII Unit Separator — never in a field value).
 const FIELD_SEP: char = '\u{1f}';
 
-/// One resolved host, serialized to Kotlin as `key␟name␟addr␟port␟fp␟pair␟mac␟os`
+/// One resolved host, serialized to Kotlin as `key␟name␟addr␟port␟fp␟pair␟mac␟os␟mgmt`
 /// (`␟` = [`FIELD_SEP`]). Records are newline-joined in a poll snapshot; [`Host::encode`] strips
 /// the framing bytes from every field so no value can break it. New fields append (the Kotlin
 /// parser tolerates both arities), never reorder.
@@ -49,6 +49,10 @@ struct Host {
     /// OS-identity chain from the mDNS `os` TXT (`linux/fedora/bazzite`, ...), for the host
     /// card's OS icon. Empty if absent (older host).
     os: String,
+    /// Management-API port from the mDNS `mgmt` TXT — where the game library is served, distinct
+    /// from `port` (the native QUIC plane). `0` if absent. Kotlin persists it on the host record so
+    /// a host that moved off 47990 keeps its library once mDNS is no longer reachable.
+    mgmt: u16,
 }
 
 impl Host {
@@ -61,7 +65,7 @@ impl Host {
             s.replace(['\n', '\r', FIELD_SEP], "")
         }
         format!(
-            "{}{FIELD_SEP}{}{FIELD_SEP}{}{FIELD_SEP}{}{FIELD_SEP}{}{FIELD_SEP}{}{FIELD_SEP}{}{FIELD_SEP}{}",
+            "{}{FIELD_SEP}{}{FIELD_SEP}{}{FIELD_SEP}{}{FIELD_SEP}{}{FIELD_SEP}{}{FIELD_SEP}{}{FIELD_SEP}{}{FIELD_SEP}{}",
             clean(&self.key),
             clean(&self.name),
             clean(&self.addr),
@@ -70,6 +74,7 @@ impl Host {
             clean(&self.pair),
             clean(&self.mac),
             clean(&self.os),
+            self.mgmt,
         )
     }
 }
@@ -193,6 +198,8 @@ fn resolve(info: &ResolvedService) -> Option<Host> {
         pair: val("pair"),
         mac: val("mac"),
         os: val("os"),
+        // 0 = the host didn't advertise one (older host); Kotlin then falls back to 47990.
+        mgmt: val("mgmt").parse().unwrap_or(0),
     })
 }
 
@@ -213,7 +220,7 @@ pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeDiscoverySt
 }
 
 /// `NativeBridge.nativeDiscoveryPoll(handle): String` — the current resolved-host snapshot,
-/// newline-joined records of `key␟name␟addr␟port␟fp␟pair␟mac␟os` (`␟` = U+001F). Empty string = no hosts /
+/// newline-joined records of `key␟name␟addr␟port␟fp␟pair␟mac␟os␟mgmt` (`␟` = U+001F). Empty string = no hosts /
 /// `0` handle. Poll ~1 Hz from the UI thread (cheap: a mutex lock + string build).
 #[unsafe(no_mangle)]
 pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeDiscoveryPoll<'local>(
@@ -277,10 +284,11 @@ mod tests {
             pair: "required".into(),
             mac: "aa:bb:cc:dd:ee:ff".into(),
             os: "linux/fedora/bazzite".into(),
+            mgmt: 47991,
         };
         let encoded = h.encode();
         let fields: Vec<&str> = encoded.split(FIELD_SEP).collect();
-        assert_eq!(fields.len(), 8);
+        assert_eq!(fields.len(), 9);
         assert_eq!(fields[0], "host-123");
         assert_eq!(fields[1], "home-worker-2");
         assert_eq!(fields[2], "192.168.1.70");
@@ -289,6 +297,9 @@ mod tests {
         assert_eq!(fields[5], "required");
         assert_eq!(fields[6], "aa:bb:cc:dd:ee:ff");
         assert_eq!(fields[7], "linux/fedora/bazzite");
+        // A NON-default port on purpose: the whole point of carrying this field is the host that
+        // moved off 47990, so a test pinned to the default would pass against a hardcoded value.
+        assert_eq!(fields[8], "47991");
         assert!(
             !encoded.contains('\n'),
             "a record must never contain the record separator"
@@ -308,13 +319,11 @@ mod tests {
             pair: "required\n".into(),
             mac: "aa:bb\u{1f}cc".into(),
             os: "linux\u{1f}evil/arch".into(),
+            // A numeric field cannot smuggle a separator — it is formatted from a u16, not cleaned.
+            mgmt: 47991,
         };
         let encoded = h.encode();
-        assert_eq!(
-            encoded.matches(FIELD_SEP).count(),
-            7,
-            "exactly eight fields"
-        );
+        assert_eq!(encoded.matches(FIELD_SEP).count(), 8, "exactly nine fields");
         assert!(!encoded.contains('\n') && !encoded.contains('\r'));
         let fields: Vec<&str> = encoded.split(FIELD_SEP).collect();
         assert_eq!(fields[0], "kinjected");

clients/android/native/src/session/clipboard.rs

@@ -50,6 +50,21 @@ pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeClipSupport
     client(handle).is_some_and(|h| h.client.host_caps() & HOST_CAP_CLIPBOARD != 0)
 }
 
+/// `NativeBridge.nativeHostMgmtPort(handle)` — the management-API port the host reported in this
+/// session's `Welcome`, or `0` if it advertised none (older host / no management API).
+///
+/// Kotlin persists this on the host record, which is what lets the library screen reach a host that
+/// moved its mgmt port off 47990 WITHOUT ever having seen an mDNS advert — the VPN / routed-subnet
+/// / added-by-address cases, where the `mgmt` TXT the discovery path relies on never arrives.
+#[unsafe(no_mangle)]
+pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeHostMgmtPort(
+    _env: EnvUnowned,
+    _this: JObject,
+    handle: jlong,
+) -> jint {
+    client(handle).map_or(0, |h| jint::from(h.client.mgmt_port()))
+}
+
 /// `NativeBridge.nativeClipControl(handle, enabled)` — session-level opt-in/out. Nothing
 /// clipboard-related happens on either side until an `enabled: true` crosses.
 #[unsafe(no_mangle)]

clients/apple/Sources/PunktfunkClient/ContentView.swift

@@ -354,9 +354,14 @@ struct ContentView: View {
                 // Persist on the next runloop tick: HostStore is an ObservableObject, and mutating
                 // its @Published from inside .onChange (a view-update callback) trips SwiftUI's
                 // "Publishing changes from within view updates". A one-tick delay is imperceptible.
+                // The session's own Welcome told us where this host's library lives — the one
+                // source that does not need an mDNS advert, so it also covers a host reached by
+                // address over a VPN. 0 = not advertised; updateMgmtPort ignores it.
+                let liveMgmtPort = model.connection?.hostMgmtPort
                 let store = store
                 DispatchQueue.main.async {
                     store.markConnected(host.id)
+                    store.updateMgmtPort(host.id, port: liveMgmtPort)
                     if let approvedFingerprint { store.pin(host.id, fingerprint: approvedFingerprint) }
                 }
             case .idle:
@@ -1262,6 +1267,9 @@ struct ContentView: View {
         if let live = discovery.hosts.first(where: { host.matches($0) }) {
             store.updateMacs(host.id, macs: live.macAddresses) // learn — on every platform
             store.updateOsChain(host.id, chain: live.osChain) // ditto for the card's OS mark
+            // ...and the mgmt port, so the library keeps working against a host that moved it once
+            // this device can no longer see the advert (VPN, routed subnet, multicast-dead Wi-Fi).
+            store.updateMgmtPort(host.id, port: live.mgmtPort)
         } else if autoWakeEnabled, PunktfunkConnection.wakeOnLANAvailable, !host.wakeMacs.isEmpty {
             // Auto-wake only: fire the up-front packet so a genuinely-asleep host is booting while the
             // dial times out. With auto-wake off, connects go straight through (no packet).
@@ -1320,6 +1328,7 @@ struct ContentView: View {
         guard !model.isBusy else { return }
         let host = StoredHost(
             name: d.name, address: d.host, port: d.port,
+            mgmtPort: d.mgmtPort,
             macAddresses: d.macAddresses.isEmpty ? nil : d.macAddresses,
             osChain: d.osChain.isEmpty ? nil : d.osChain)
         store.add(host)

clients/apple/Sources/PunktfunkClient/Stores/HostStore.swift

@@ -162,6 +162,17 @@ final class HostStore: ObservableObject {
         hosts[i].osChain = chain
     }
 
+    /// Learn/refresh this host's management-API port from its live advert — same contract as
+    /// `updateMacs`. Until this existed, `StoredHost.mgmtPort` was declared and read but never
+    /// written, so `effectiveMgmtPort` always answered 47990 and a host that had moved its mgmt
+    /// port simply had no working library here.
+    func updateMgmtPort(_ hostID: UUID, port: UInt16?) {
+        guard let port, port > 0,
+              let i = hosts.firstIndex(where: { $0.id == hostID }),
+              hosts[i].mgmtPort != port else { return }
+        hosts[i].mgmtPort = port
+    }
+
     /// Bind this host to a settings profile, or to "Default settings" (nil) — the ONLY way the
     /// default changes. A one-off "Connect with ▸" deliberately never lands here (§5.2:
     /// predictable, not sticky).

clients/apple/Sources/PunktfunkKit/Connection/HostDiscovery.swift

@@ -61,6 +61,16 @@ public struct DiscoveredHost: Identifiable, Sendable, Equatable {
     /// (`sanitizeOsChain`) — drives the host card's OS mark and is persisted like the MACs.
     /// Empty when not advertised (older host). Advisory/unauthenticated like the rest.
     public let osChain: String
+    /// The host's management-API port (mDNS `mgmt` TXT) — where the game library is served, NOT
+    /// `port`, which is the native QUIC plane. nil when not advertised (older host), and the
+    /// client then assumes `punktfunkDefaultMgmtPort`.
+    ///
+    /// Persisted onto the saved host like the MACs and the OS chain, and for a sharper reason:
+    /// `StoredHost.mgmtPort` has existed all along but nothing ever wrote it, so
+    /// `effectiveMgmtPort` always resolved to 47990. A host that moved its mgmt port off 47990 —
+    /// the supported way to share a machine with a Sunshine fork, whose web UI owns that port —
+    /// therefore had no working library on any Apple client at all.
+    public let mgmtPort: UInt16?
 }
 
 @MainActor
@@ -211,12 +221,12 @@ public final class HostDiscovery: ObservableObject {
     public static func debugAdvert(
         id: String, name: String, host: String, port: UInt16 = 9777,
         fingerprintHex: String? = nil, requiresPairing: Bool = false, allowsTofu: Bool = true,
-        macAddresses: [String] = [], osChain: String = ""
+        macAddresses: [String] = [], osChain: String = "", mgmtPort: UInt16? = nil
     ) -> DiscoveredHost {
         DiscoveredHost(
             id: id, name: name, host: host, port: port, fingerprintHex: fingerprintHex,
             requiresPairing: requiresPairing, allowsTofu: allowsTofu,
-            macAddresses: macAddresses, osChain: osChain)
+            macAddresses: macAddresses, osChain: osChain, mgmtPort: mgmtPort)
     }
     #endif
 
@@ -429,6 +439,7 @@ public final class HostDiscovery: ObservableObject {
         var id: String?
         var macs: [String] = []
         var osChain = ""
+        var mgmtPort: UInt16?
         if case let .bonjour(txt) = result.metadata {
             fp = entry(txt, "fp")
             pair = entry(txt, "pair")
@@ -438,13 +449,16 @@ public final class HostDiscovery: ObservableObject {
                 .map { $0.trimmingCharacters(in: .whitespaces) }
                 .filter { !$0.isEmpty }
             osChain = sanitizeOsChain(entry(txt, "os") ?? "")
+            // Unauthenticated input, so range-check rather than trust: a non-numeric or 0 value
+            // means "not advertised" and the client falls back to the default.
+            mgmtPort = entry(txt, "mgmt").flatMap(UInt16.init).flatMap { $0 > 0 ? $0 : nil }
         }
         return DiscoveredHost(
             id: (id?.isEmpty == false) ? id! : name,
             name: name, host: address, port: port,
             fingerprintHex: fp, requiresPairing: pair == "required",
             allowsTofu: pair == "optional", macAddresses: macs,
-            osChain: osChain)
+            osChain: osChain, mgmtPort: mgmtPort)
     }
 
     private static func key(_ result: NWBrowser.Result) -> String {

clients/apple/Sources/PunktfunkKit/Connection/PunktfunkConnection.swift

@@ -452,6 +452,14 @@ public final class PunktfunkConnection {
     /// The host capability bitfield (`Welcome.host_caps`): `PUNKTFUNK_HOST_CAP_GAMEPAD_STATE` /
     /// `PUNKTFUNK_HOST_CAP_CLIPBOARD`. `0` for an older host that didn't say.
     public private(set) var hostCaps: UInt8 = 0
+    /// The host's management-API port, from this session's `Welcome` — where its game library is
+    /// served. `0` when the host advertised none (an older host, or one with no management API);
+    /// resolve through `StoredHost.effectiveMgmtPort` rather than dialing a `0`.
+    ///
+    /// Read this after a connect and persist it: it is the only source that does not depend on
+    /// mDNS, so it is what makes a moved mgmt port work for a host reached over a VPN or added by
+    /// address on a network where discovery never functions.
+    public private(set) var hostMgmtPort: UInt16 = 0
     /// Whether this host advertises the shared clipboard (`HOST_CAP_CLIPBOARD`) — the gate for
     /// offering the clipboard toggle. Absent on an older host, or one whose operator policy
     /// (`PUNKTFUNK_CLIPBOARD=off`) keeps the feature dark.
@@ -677,6 +685,12 @@ public final class PunktfunkConnection {
         var caps: UInt8 = 0
         _ = punktfunk_connection_host_caps(handle, &caps)
         hostCaps = caps
+        // Where this host serves its game library, straight from the session's Welcome. 0 = the
+        // host advertised none (older host / no management API), and the caller keeps whatever it
+        // already had. This is the answer that does NOT require an mDNS advert to have been seen.
+        var mgmt: UInt16 = 0
+        _ = punktfunk_connection_mgmt_port(handle, &mgmt)
+        hostMgmtPort = mgmt
     }
 
     /// A bandwidth speed-test measurement (see `startSpeedTest`). Partial until `done`.

clients/cli/src/main.rs

@@ -796,7 +796,9 @@ from the config directory for a true factory reset."
             );
             return NEEDS_INTERACTION;
         }
-        match library::fetch_games(&host.addr, library::DEFAULT_MGMT_PORT, &identity, pin) {
+        // The port this host actually serves its library on — learned from its advert and saved,
+        // falling back to 47990. Reaching for the constant here is what broke a moved port.
+        match library::fetch_games(&host.addr, host.effective_mgmt_port(), &identity, pin) {
             Ok(games) => {
                 if has(args, "--json") {
                     let rows: Vec<serde_json::Value> = games

clients/linux/src/ui_hosts.rs

@@ -1108,6 +1108,18 @@ impl HostsPage {
                 {
                     crate::trust::learn_os(&k.fp_hex, &k.addr, k.port, &a.os);
                 }
+                // Same for its management port — and this one is not cosmetic: without it a host
+                // that moved off 47990 loses its library the moment mDNS is unavailable, because
+                // the advert was the only place the real port ever lived.
+                if let Some(a) = self
+                    .adverts
+                    .values()
+                    .find(|a| matches(k, a) && a.mgmt_port.is_some())
+                {
+                    if let Some(p) = a.mgmt_port {
+                        crate::trust::learn_mgmt_port(&k.fp_hex, &k.addr, k.port, p);
+                    }
+                }
                 saved.push_back(HostCard {
                     connecting: self.connecting.as_deref() == Some(k.fp_hex.as_str()),
                     kind: CardKind::Saved {
@@ -1183,18 +1195,33 @@ impl HostsPage {
         });
     }
 
-    /// The advertised mgmt port for the host `req` points at, when a matching live
-    /// advert carries the `mgmt` TXT.
+    /// The mgmt port for the host `req` points at: a matching live advert's `mgmt` TXT first,
+    /// else the port a previous advert taught us and we saved on the host record.
+    ///
+    /// The saved rung is not redundant. Reading the advert alone meant a host that had moved its
+    /// mgmt port off 47990 served its library on the LAN and nowhere else — over a VPN, a routed
+    /// subnet, or any multicast-dead network there is no advert to read, and the fallback silently
+    /// went back to a port nothing was listening on. `None` here still means "assume the default".
     fn mgmt_port_for(&self, req: &ConnectRequest) -> Option<u16> {
-        self.adverts
+        let matches_req = |fp: &str, addr: &str, port: u16| {
+            req.fp_hex
+                .as_deref()
+                .is_some_and(|want| !fp.is_empty() && fp == want)
+                || (addr == req.addr && port == req.port)
+        };
+        if let Some(p) = self
+            .adverts
             .values()
-            .find(|a| {
-                req.fp_hex
-                    .as_deref()
-                    .is_some_and(|fp| !a.fp_hex.is_empty() && a.fp_hex == fp)
-                    || (a.addr == req.addr && a.port == req.port)
-            })
+            .find(|a| matches_req(&a.fp_hex, &a.addr, a.port))
             .and_then(|a| a.mgmt_port)
+        {
+            return Some(p);
+        }
+        crate::trust::KnownHosts::load()
+            .hosts
+            .iter()
+            .find(|h| matches_req(&h.fp_hex, &h.addr, h.port))
+            .and_then(|h| h.mgmt_port)
     }
 
     /// Rename a saved host — an entry in an alert, then upsert + refresh.

clients/session/src/console.rs

@@ -73,8 +73,11 @@ pub fn run(target: Option<&str>) -> u8 {
                 paired: k.is_some_and(|h| h.paired) || fake,
                 saved: k.is_some(),
                 online: false,
+                // Explicit --mgmt wins; else the port this host's advert taught us and we saved;
+                // else 47990. The middle rung is what survives mDNS being unavailable later.
                 mgmt_port: arg_value("--mgmt")
                     .and_then(|p| p.parse().ok())
+                    .or_else(|| k.and_then(|h| h.mgmt_port))
                     .unwrap_or(library::DEFAULT_MGMT_PORT),
                 can_wake: false,
                 last_used: k.and_then(|h| h.last_used),
@@ -181,7 +184,7 @@ pub fn run(target: Option<&str>) -> u8 {
         vsync: settings_at_start.vsync,
         allow_vrr: settings_at_start.allow_vrr,
         json_status,
-        on_connected: Some(Box::new(move |fingerprint: [u8; 32]| {
+        on_connected: Some(Box::new(move |fingerprint: [u8; 32], mgmt_port: u16| {
             let fp_hex = trust::hex(&fingerprint);
             trust::touch_last_used(&fp_hex);
             // A request-access connect just succeeded → the operator approved us. Save the
@@ -191,6 +194,10 @@ pub fn run(target: Option<&str>) -> u8 {
                     trust::persist_host(&p.name, &p.addr, p.port, &fp_hex, true);
                 }
             }
+            // Where this host serves its library, from the session's own Welcome — recorded
+            // AFTER the persist above so a host saved by this very connect gets it too. `0` =
+            // the host advertised none, and the call is a no-op.
+            trust::learn_mgmt_port_by_fp(&fp_hex, mgmt_port);
         })),
         overlay: Some(Box::new(overlay)),
         window_size: crate::session_main::window_size(&settings_at_start),
@@ -682,6 +689,12 @@ impl ServiceState {
                         || (d.addr == h.addr && d.port == h.port)
                 });
                 let online = advert.is_some() || probed.get(&key).copied().unwrap_or(false);
+                // Write the advertised mgmt port down while the host is visible, so this console
+                // keeps working against a moved port once it is not. No-op (and no disk write)
+                // when unchanged, so this is safe on every refresh tick.
+                if let Some(p) = advert.and_then(|d| d.mgmt_port) {
+                    pf_client_core::trust::learn_mgmt_port(&h.fp_hex, &h.addr, h.port, p);
+                }
                 let row = HostRow {
                     key: key.clone(),
                     name: host_display_name(&h.name, &h.addr),
@@ -691,8 +704,12 @@ impl ServiceState {
                     paired: h.paired,
                     saved: true,
                     online,
+                    // Live advert first, then what we saved from an earlier one, then 47990 —
+                    // the same three rungs `os` uses just below. Reading the advert ALONE is why
+                    // a host on a moved mgmt port lost its library the moment mDNS went quiet.
                     mgmt_port: advert
                         .and_then(|d| d.mgmt_port)
+                        .or(h.mgmt_port)
                         .unwrap_or(library::DEFAULT_MGMT_PORT),
                     can_wake: !online && !h.mac.is_empty(),
                     last_used: h.last_used,

clients/session/src/main.rs

@@ -986,9 +986,16 @@ mod session_main {
             vsync: settings.vsync,
             allow_vrr: settings.allow_vrr,
             json_status: true,
-            on_connected: Some(Box::new(|fingerprint: [u8; 32]| {
+            on_connected: Some(Box::new(|fingerprint: [u8; 32], mgmt_port: u16| {
+                let fp = trust::hex(&fingerprint);
                 // This host's card carries the accent bar in the desktop client now.
-                trust::touch_last_used(&trust::hex(&fingerprint));
+                trust::touch_last_used(&fp);
+                // Save where this host serves its library, learned from the session's own
+                // Welcome rather than an mDNS advert — so it keeps working on a network where
+                // discovery never does. `0` = the host advertised none; leave what we have.
+                if mgmt_port != 0 {
+                    trust::learn_mgmt_port_by_fp(&fp, mgmt_port);
+                }
             })),
             // The Skia console UI (stats OSD, capture HUD) — compiled out of the
             // power-user build (`--no-default-features` drops the `ui` feature).

clients/windows/src/app/hosts.rs

@@ -691,6 +691,7 @@ pub(crate) fn hosts_page(props: &HostsProps, cx: &mut RenderCx) -> Element {
                 fp_hex: Some(k.fp_hex.clone()),
                 pair_optional: false,
                 mac: k.mac.clone(),
+                mgmt_port: k.mgmt_port,
                 profile: None,
                 launch: None,
             };
@@ -715,6 +716,18 @@ pub(crate) fn hosts_page(props: &HostsProps, cx: &mut RenderCx) -> Element {
             }) {
                 crate::trust::learn_os(&k.fp_hex, &k.addr, k.port, &a.os);
             }
+            // Same for its management port — load-bearing, unlike the two above: a host moved off
+            // 47990 loses its library entirely once mDNS is gone unless we write the port down.
+            if let Some(p) = hosts
+                .iter()
+                .find(|h| {
+                    (h.fp_hex == k.fp_hex || (h.addr == k.addr && h.port == k.port))
+                        && h.mgmt_port.is_some()
+                })
+                .and_then(|h| h.mgmt_port)
+            {
+                crate::trust::learn_mgmt_port(&k.fp_hex, &k.addr, k.port, p);
+            }
             let can_wake = !online && !k.mac.is_empty();
             let menu = {
                 let (svc, target) = (props.svc.clone(), target.clone());
@@ -1046,6 +1059,7 @@ pub(crate) fn hosts_page(props: &HostsProps, cx: &mut RenderCx) -> Element {
                 fp_hex: (!h.fp_hex.is_empty()).then(|| h.fp_hex.clone()),
                 pair_optional: h.pair == "optional",
                 mac: h.mac.clone(),
+                mgmt_port: h.mgmt_port,
                 profile: None,
                 launch: None,
             };
@@ -1140,6 +1154,11 @@ pub(crate) fn hosts_page(props: &HostsProps, cx: &mut RenderCx) -> Element {
                     fp_hex: None,
                     pair_optional: false,
                     mac: Vec::new(),
+                    // Added by hand, so nothing has told us where its mgmt API is: fall back to
+                    // 47990 (exactly today's behaviour) until an advert teaches us otherwise.
+                    // A host that moved its mgmt port AND is never visible on mDNS still needs the
+                    // host to announce the port in-band — see the note in `Target::mgmt_port`.
+                    mgmt_port: None,
                     profile: None,
                     launch: None,
                 },

clients/windows/src/app/library.rs

@@ -104,7 +104,7 @@ pub(crate) fn start_fetch(ctx: &Arc<AppCtx>, set_library: &AsyncSetState<Library
             let mut state = LibraryState::default();
             let games = match library::fetch_games(
                 &target.addr,
-                library::DEFAULT_MGMT_PORT,
+                target.mgmt_port.unwrap_or(library::DEFAULT_MGMT_PORT),
                 &identity,
                 pin,
             ) {
@@ -120,7 +120,10 @@ pub(crate) fn start_fetch(ctx: &Arc<AppCtx>, set_library: &AsyncSetState<Library
             }
 
             // Seed cached posters; queue the art pipeline for the rest.
-            let base = library::base_url(&target.addr, library::DEFAULT_MGMT_PORT);
+            let base = library::base_url(
+                &target.addr,
+                target.mgmt_port.unwrap_or(library::DEFAULT_MGMT_PORT),
+            );
             let cache = art_cache_dir();
             let mut jobs: VecDeque<(String, Vec<String>)> = VecDeque::new();
             for g in &games {

clients/windows/src/app/mod.rs

@@ -103,6 +103,11 @@ pub(crate) struct Target {
     /// Wake-on-LAN MAC(s) for this host (from the saved store or the live advert) — used to send a
     /// magic packet before connecting to an offline host. Empty when none is known.
     pub(crate) mac: Vec<String>,
+    /// This host's management-API port (saved store or live advert), where the library screen
+    /// fetches from. `None` = unknown, use [`pf_client_core::library::DEFAULT_MGMT_PORT`]. Carried
+    /// on the target for the same reason as `mac`: the library screen has no `KnownHost` in hand,
+    /// and assuming 47990 there is what made a moved mgmt port work on the LAN but not over a VPN.
+    pub(crate) mgmt_port: Option<u16>,
     /// A ONE-OFF settings profile for this connect ("Connect with"): `Some(id)` overrides the
     /// host's binding for this launch, `Some("")` forces the global defaults on a bound host,
     /// `None` honors the binding. It never rebinds anything — the default changes only through
@@ -406,6 +411,7 @@ fn root(cx: &mut RenderCx, ctx: &Arc<AppCtx>) -> Element {
                         fp_hex: p.host.fp_hex.clone(),
                         pair_optional: false,
                         mac: p.host.mac.clone(),
+                        mgmt_port: p.host.mgmt_port,
                         profile: p.profile_override.clone(),
                         launch: None, // routed explicitly below (initiate_launch*)
                     };
@@ -447,6 +453,9 @@ fn root(cx: &mut RenderCx, ctx: &Arc<AppCtx>) -> Element {
                         fp_hex: u.fp.clone(),
                         pair_optional: false,
                         mac: Vec::new(),
+                        // A link carries no mgmt port (nor a MAC), so this stays unknown until
+                        // an advert teaches it — same fallback as the hand-added case.
+                        mgmt_port: None,
                         profile: u.profile.clone(),
                         launch: u.launch.clone(),
                     };

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

@@ -313,6 +313,20 @@ pub struct KnownHost {
     /// sleep. `default` (and elided when empty) so pre-existing stores load unchanged.
     #[serde(default, skip_serializing_if = "String::is_empty")]
     pub os: String,
+    /// The host's management-API port (mDNS `mgmt` TXT), where the game library is served —
+    /// distinct from `port`, which is the native QUIC plane. Learned from the advert while the
+    /// host is online and persisted here for the same reason as `mac` and `os`: so it survives the
+    /// advert going away.
+    ///
+    /// That is not a cosmetic loss like a missing OS icon. A host that moved its mgmt port off
+    /// 47990 — the supported fix for sharing a machine with a Sunshine fork, whose web UI owns
+    /// that port — was reachable only for as long as mDNS was: on a VPN, a routed subnet, or a
+    /// multicast-dead network the library silently went blank, because the port the client had
+    /// already been told was never written down. `None` = never learned, resolve via
+    /// [`KnownHost::effective_mgmt_port`]. Optional + `default` so pre-existing stores load
+    /// (the Apple client's `StoredHost.mgmtPort` is the same field for the same reason).
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub mgmt_port: Option<u16>,
     /// Share this machine's clipboard with THIS host (design/clipboard-and-file-transfer.md
     /// §5.3 — the Apple client's `StoredHost.clipboardSync`). Per-host, not global: handing a
     /// host your clipboard is a trust decision about that host. Default off; the host must
@@ -353,6 +367,7 @@ impl Default for KnownHost {
             last_used: None,
             mac: Vec::new(),
             os: String::new(),
+            mgmt_port: None,
             clipboard_sync: false,
             profile_id: None,
             pinned_profiles: Vec::new(),
@@ -362,6 +377,17 @@ impl Default for KnownHost {
 }
 
 impl KnownHost {
+    /// Where this host's management API actually is: the port learned from its advert, else the
+    /// compiled-in 47990. The twin of the Apple client's `StoredHost.effectiveMgmtPort`.
+    ///
+    /// Every library/art call resolves through this rather than reaching for
+    /// [`crate::library::DEFAULT_MGMT_PORT`] directly — that constant is the FALLBACK, not the
+    /// answer, and call sites that treated it as the answer are why a moved port only worked while
+    /// mDNS was up.
+    pub fn effective_mgmt_port(&self) -> u16 {
+        self.mgmt_port.unwrap_or(crate::library::DEFAULT_MGMT_PORT)
+    }
+
     /// This host's pinned profiles that still exist, in card order, without duplicates — what
     /// a grid renders. Dangling pins (the profile was deleted) simply disappear, per design
     /// §5.2a: a pin is presentation state, never a reason to show an error.
@@ -506,6 +532,13 @@ impl KnownHosts {
             if !entry.os.is_empty() {
                 h.os = entry.os;
             }
+            // And for the learned mgmt port. Stated explicitly rather than left to the
+            // does-not-mention-it rule below: this one is load-bearing (a host that moved off
+            // 47990 is unreachable for the library without it), so a reconnect upsert that
+            // carries `None` must visibly not clear what a discovery taught us.
+            if entry.mgmt_port.is_some() {
+                h.mgmt_port = entry.mgmt_port;
+            }
             // Everything below is state the user set ON this record, which a refresh (a
             // reconnect, a re-pair, a rediscovery) never carries and therefore must never
             // clear: the per-host clipboard decision — which survives today only because this
@@ -581,6 +614,9 @@ impl KnownHosts {
             if h.os.is_empty() {
                 h.os = old.os;
             }
+            if h.mgmt_port.is_none() {
+                h.mgmt_port = old.mgmt_port;
+            }
             if h.profile_id.is_none() {
                 h.profile_id = old.profile_id;
             }
@@ -692,6 +728,27 @@ pub fn learn_os(fp_hex: &str, addr: &str, port: u16, os: &str) {
     let _ = known.save();
 }
 
+/// Learn/refresh a saved host's management-API port from its live advert (mDNS `mgmt` TXT),
+/// matched like [`learn_mac`]: by fingerprint or address. No-op — and no disk write — when
+/// unchanged, so the hosts page can call it on every discovery tick without churning the store.
+///
+/// This is what makes a moved mgmt port outlive mDNS. Until it existed the port was read straight
+/// off the live advert and thrown away, so the library worked on the LAN and went blank over a VPN.
+pub fn learn_mgmt_port(fp_hex: &str, addr: &str, port: u16, mgmt_port: u16) {
+    if mgmt_port == 0 {
+        return;
+    }
+    let mut known = KnownHosts::load();
+    let Some(h) = learn_target(&mut known, fp_hex, addr, port) else {
+        return;
+    };
+    if h.mgmt_port == Some(mgmt_port) {
+        return;
+    }
+    h.mgmt_port = Some(mgmt_port);
+    let _ = known.save();
+}
+
 /// Re-key a saved host's address/port after it rediscovered on a new DHCP lease (matched by
 /// fingerprint). No-op — and no disk write — when unchanged. Called from the wake-and-wait flow when
 /// a woken host reappears on a different IP than the stored one, so this and future connects dial the
@@ -725,6 +782,28 @@ pub fn touch_last_used(fp_hex: &str) {
     }
 }
 
+/// Save a host's management-API port learned from the **session's own `Welcome`**, keyed by
+/// fingerprint alone — the identity a just-connected client is certain of.
+///
+/// This is the mDNS-free path, and the one that matters most: [`learn_mgmt_port`] can only fire
+/// where an advert is visible, whereas this fires on any successful connect, including a host
+/// added by IP on a network where discovery has never worked. No-op — and no disk write — when
+/// the fingerprint isn't stored or the value is unchanged, so it is safe on every connect.
+pub fn learn_mgmt_port_by_fp(fp_hex: &str, mgmt_port: u16) {
+    if fp_hex.is_empty() || mgmt_port == 0 {
+        return;
+    }
+    let mut known = KnownHosts::load();
+    let Some(h) = known.hosts.iter_mut().find(|h| h.fp_hex == fp_hex) else {
+        return;
+    };
+    if h.mgmt_port == Some(mgmt_port) {
+        return;
+    }
+    h.mgmt_port = Some(mgmt_port);
+    let _ = known.save();
+}
+
 /// Run the SPAKE2 PIN ceremony against a host. `device_name` is the label the HOST
 /// stores this client under (its paired-devices list); the 90 s budget covers a
 /// human-typed PIN. Returns the host's now-verified certificate fingerprint to pin.
@@ -1781,6 +1860,9 @@ mod tests {
                 last_used: Some(1000),
                 mac: vec!["aa:bb:cc:dd:ee:ff".into()],
                 os: "linux/fedora/bazzite".into(),
+                // Deliberately NOT 47990: a host that moved its mgmt port is the case this field
+                // exists for, so the default would make the assertions below pass vacuously.
+                mgmt_port: Some(47991),
                 clipboard_sync: true,
                 profile_id: Some("aaaaaaaaaaaa".into()),
                 pinned_profiles: vec!["bbbbbbbbbbbb".into()],
@@ -1804,6 +1886,9 @@ mod tests {
         assert_eq!(h.mac, vec!["aa:bb:cc:dd:ee:ff".to_string()]);
         // The learned OS chain rides the same rule as `mac`: a carrier-less upsert keeps it.
         assert_eq!(h.os, "linux/fedora/bazzite");
+        // And the learned mgmt port. If a reconnect could reset this to None the host would fall
+        // back to 47990 and its library would 404 — the exact regression this rule prevents.
+        assert_eq!(h.mgmt_port, Some(47991));
         assert!(h.clipboard_sync);
         assert_eq!(h.profile_id.as_deref(), Some("aaaaaaaaaaaa"));
         assert_eq!(h.pinned_profiles, vec!["bbbbbbbbbbbb".to_string()]);
@@ -1823,6 +1908,51 @@ mod tests {
         assert_eq!(k.hosts[0].pinned_profiles, vec!["dddddddddddd".to_string()]);
     }
 
+    /// The mgmt port a host advertises has to OUTLIVE the advert: a store written before the field
+    /// existed must load, resolve to 47990, and then take and keep a learned value. Without the
+    /// middle rung a host moved off 47990 (to share a box with a Sunshine fork, whose web UI owns
+    /// that port) served its library on the LAN and nowhere else — over a VPN or a routed subnet
+    /// there is no advert to read and the client silently went back to a dead port.
+    #[test]
+    fn mgmt_port_survives_a_store_that_predates_it_and_then_persists() {
+        // A store written before the field existed: no `mgmt_port` key at all.
+        let old = r#"{"hosts":[{
+            "name": "Gaming PC", "addr": "192.168.1.50", "port": 9777,
+            "fp_hex": "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
+            "paired": true
+        }]}"#;
+        let mut k: KnownHosts = serde_json::from_str(old).unwrap();
+        assert_eq!(k.hosts[0].mgmt_port, None, "absent key decodes to None");
+        assert_eq!(
+            k.hosts[0].effective_mgmt_port(),
+            crate::library::DEFAULT_MGMT_PORT,
+            "unknown resolves to the compiled-in default, i.e. today's behaviour"
+        );
+        // Unset stays out of the serialized form, so an untouched store is byte-stable.
+        assert!(!serde_json::to_string(&k).unwrap().contains("mgmt_port"));
+
+        // Learning one (what a discovery tick does) takes effect and round-trips.
+        k.hosts[0].mgmt_port = Some(47991);
+        assert_eq!(k.hosts[0].effective_mgmt_port(), 47991);
+        let round: KnownHosts = serde_json::from_str(&serde_json::to_string(&k).unwrap()).unwrap();
+        assert_eq!(round.hosts[0].mgmt_port, Some(47991));
+
+        // A re-key carries it onto the surviving record — otherwise a host that regenerated its
+        // identity would silently drop back to 47990.
+        let fresh = fp('a');
+        let mut k2 = k;
+        k2.upsert_trusted(KnownHost {
+            name: "Gaming PC".into(),
+            addr: "192.168.1.50".into(),
+            port: 9777,
+            fp_hex: fresh.clone(),
+            paired: true,
+            ..Default::default()
+        });
+        let kept = k2.hosts.iter().find(|h| h.fp_hex == fresh).unwrap();
+        assert_eq!(kept.mgmt_port, Some(47991), "re-key must not lose the port");
+    }
+
     /// A host that regenerated its identity (reinstall, wiped ProgramData, re-key) ends up with
     /// ONE record for its address — the live one. This is the `.173` lockout: `upsert` keys on
     /// the fingerprint, so the re-paired host used to be appended beside the dead record, and
@@ -1840,6 +1970,7 @@ mod tests {
                 last_used: Some(1000),
                 mac: vec!["aa:bb:cc:dd:ee:ff".into()],
                 os: "windows".into(),
+                mgmt_port: Some(47991),
                 clipboard_sync: true,
                 profile_id: Some("aaaaaaaaaaaa".into()),
                 pinned_profiles: vec!["bbbbbbbbbbbb".into()],
@@ -1864,6 +1995,9 @@ mod tests {
         // What describes the BOX rides along, so a reinstall doesn't cost the user their setup.
         assert_eq!(h.mac, vec!["aa:bb:cc:dd:ee:ff".to_string()]);
         assert_eq!(h.os, "windows");
+        // The mgmt port describes the BOX, not the retired certificate: a reinstall must not send
+        // the library back to 47990 on a host that serves it somewhere else.
+        assert_eq!(h.mgmt_port, Some(47991));
         assert_eq!(h.profile_id.as_deref(), Some("aaaaaaaaaaaa"));
         assert_eq!(h.pinned_profiles, vec!["bbbbbbbbbbbb".to_string()]);
         assert_eq!(h.last_used, Some(1000));

crates/pf-frame/Cargo.toml

@@ -21,6 +21,10 @@ tracing = "0.1"
 # `FramePayload::Cuda` owns a zero-copy `DeviceBuffer`; `libc` for the per-thread `setpriority`.
 pf-zerocopy = { path = "../pf-zerocopy" }
 libc = "0.2"
+# The rtkit fallback in `thread_qos` (one blocking system-bus call per boosted thread). Same zbus
+# the host already pulls via ashpd; `tokio` mirrors ashpd's backend choice so this adds the
+# `blocking-api` surface without changing the resolved I/O backend, and no default `async-io`.
+zbus = { version = "5", default-features = false, features = ["tokio", "blocking-api"] }
 
 [target.'cfg(target_os = "windows")'.dependencies]
 # The DXGI capture identity (`WinCaptureTarget`/`D3d11Frame`/`pack_luid`/`make_device`) + the GPU

crates/pf-frame/src/thread_qos.rs

@@ -44,10 +44,9 @@ pub fn boost_thread_priority(critical: bool) {
         // Best-effort nice of the CALLING thread. On Linux `setpriority(PRIO_PROCESS, 0, …)` acts on
         // the calling thread (the kernel resolves who==0 to the current task/tid), and both call
         // sites run inside their worker thread — so this nices exactly the capture/encode (critical)
-        // and send (non-critical) threads, nothing else. Silently no-ops without CAP_SYS_NICE / a
-        // raised RLIMIT_NICE, which is fine. We deliberately do NOT use SCHED_RR/FIFO by default: a
-        // realtime CPU class can preempt the compositor AND the game's own render thread, adding the
-        // very frame-time we refuse to add (opt-in only — see PUNKTFUNK_SCHED_RR).
+        // and send (non-critical) threads, nothing else. We deliberately do NOT use SCHED_RR/FIFO by
+        // default: a realtime CPU class can preempt the compositor AND the game's own render thread,
+        // adding the very frame-time we refuse to add (opt-in only — see PUNKTFUNK_SCHED_RR).
         let nice = if critical { -10 } else { -5 };
         // SAFETY: `setpriority` takes three by-value integers and no pointers, so there is nothing to
         // alias or outlive. `PRIO_PROCESS` with `who == 0` targets the calling task on Linux and
@@ -57,10 +56,24 @@ pub fn boost_thread_priority(critical: bool) {
         if rc == 0 {
             tracing::debug!(critical, nice, "thread nice raised");
         } else {
-            tracing::debug!(
-                critical,
-                "setpriority(nice) no-op (needs CAP_SYS_NICE / RLIMIT_NICE)"
-            );
+            // The direct call needs CAP_SYS_NICE or a raised RLIMIT_NICE, and the host binary can
+            // NEVER carry a file capability (a capped process's /proc/<pid>/exe is unreadable to
+            // KWin, which kills desktop streaming — the 0.26.0-1 field incident). RealtimeKit is
+            // the sanctioned unprivileged path: the same broker PipeWire's clients use, present on
+            // effectively every desktop install. Packaging also ships a `user@.service.d`
+            // LimitNICE drop-in so the direct call works on rtkit-less boxes — but only from the
+            // next login, and existing installs upgrade the binary alone; rtkit is what fixes the
+            // installed base. A 2026-08-14 field log showed exactly this rung missing: every
+            // fresh-launch shader storm descheduled the unprioritized audio/send threads.
+            match linux_rtkit::make_high_priority(nice) {
+                Ok(()) => tracing::debug!(critical, nice, "thread nice raised via rtkit"),
+                Err(e) => tracing::debug!(
+                    critical,
+                    reason = %e,
+                    "setpriority(nice) no-op (needs CAP_SYS_NICE / RLIMIT_NICE, and rtkit \
+                     was unavailable)"
+                ),
+            }
         }
     }
     #[cfg(not(any(target_os = "windows", target_os = "linux")))]
@@ -68,3 +81,43 @@ pub fn boost_thread_priority(critical: bool) {
         let _ = critical;
     }
 }
+
+/// RealtimeKit fallback for [`boost_thread_priority`]: ask the system-bus broker
+/// (`org.freedesktop.RealtimeKit1`) to renice the calling thread when the direct
+/// `setpriority` was refused. This is how PulseAudio/PipeWire clients get their boosts on a
+/// stock desktop — no capability anywhere, which matters here because a file capability on the
+/// host binary breaks KWin's client identification outright.
+///
+/// Only the high-priority (nice) verb is used, never `MakeThreadRealtime` — the SCHED_RR
+/// reservations in [`boost_thread_priority`]'s comment apply to rtkit-granted RR too (and the
+/// RT verb additionally demands an RLIMIT_RTTIME we don't set).
+#[cfg(target_os = "linux")]
+mod linux_rtkit {
+    /// One-shot blocking D-Bus call. Must be made from a plain worker thread, never from async
+    /// context — which already holds for every caller: `boost_thread_priority` acts on the
+    /// calling thread, so it only ever runs inside the dedicated capture/encode/send threads.
+    /// The connection is per-call rather than cached: this runs at most a handful of times per
+    /// session (thread starts), and holding a system-bus connection for the session's lifetime
+    /// to save microseconds at session start is a bad trade against a wedged bus daemon pinning
+    /// a socket in every session forever.
+    pub(super) fn make_high_priority(nice: i32) -> Result<(), zbus::Error> {
+        // SAFETY: `gettid` takes no arguments, touches no memory, and returns the calling
+        // thread's kernel tid — always valid on Linux.
+        let tid = unsafe { libc::syscall(libc::SYS_gettid) } as u64;
+        let pid = u64::from(std::process::id());
+        let conn = zbus::blocking::Connection::system()?;
+        // `MakeThreadHighPriorityWithPID(u64 process, u64 thread, i32 priority)` — priority is a
+        // nice level, floored by rtkit's MinNiceLevel (defaults well below our -10). The WithPID
+        // variant with our own pid is the explicit spelling of "this thread of this process";
+        // rtkit still authenticates the caller via the bus, so it grants nothing a plain
+        // `setpriority` caller couldn't be granted.
+        conn.call_method(
+            Some("org.freedesktop.RealtimeKit1"),
+            "/org/freedesktop/RealtimeKit1",
+            Some("org.freedesktop.RealtimeKit1"),
+            "MakeThreadHighPriorityWithPID",
+            &(pid, tid, nice),
+        )?;
+        Ok(())
+    }
+}

crates/pf-host-config/src/lib.rs

@@ -144,6 +144,30 @@ pub struct HostConfig {
     /// text ("Living Room PC"); the DNS-level `<label>.local.` target keeps using a sanitized
     /// machine-safe label, so a spacey display name can't produce an invalid mDNS record.
     pub host_name: Option<String>,
+    /// `PUNKTFUNK_MGMT_BIND` — the management API's listen address (`IP:PORT`), equivalent to the
+    /// `--mgmt-bind` CLI flag, which still wins when both are given. Unset = `0.0.0.0:47990`.
+    ///
+    /// This exists so moving the port SURVIVES: `--mgmt-bind` lives in a unit file / service
+    /// registration that a package upgrade rewrites, whereas `host.env` is operator-owned and is
+    /// the documented place every other knob lives. The motivating case is coexistence with a
+    /// Sunshine fork — 47990 is *their* web UI port as well as our management API, and it is the
+    /// only port the two share once the GameStream planes are off, so moving it is the whole fix.
+    ///
+    /// Kept as the raw string rather than a parsed `SocketAddr`: this crate is the
+    /// parse-once-from-env layer, and `main.rs` owns turning a bad value into the same
+    /// `bad --mgmt-bind (want IP:PORT)` error the flag produces, from one place.
+    pub mgmt_bind: Option<String>,
+    /// `PUNKTFUNK_NATIVE_PORT` — the native punktfunk/1 (QUIC) control port, equivalent to the
+    /// `--native-port` CLI flag, which still wins. Unset = 9777.
+    ///
+    /// Same survives-an-upgrade argument as [`Self::mgmt_bind`]: `--native-port` lives in an
+    /// ExecStart a package rewrites. Unlike the mgmt port, the CLIENT side of moving this already
+    /// worked — `KnownHost.port` is persisted per host and `--connect HOST:PORT` names it — so this
+    /// key is the last piece of making the native port genuinely movable.
+    ///
+    /// Raw string, parsed in `main.rs`, for the same reason as `mgmt_bind`: a typo'd port must be a
+    /// startup ERROR, not a silent fall back to 9777 while the operator believes they moved it.
+    pub native_port: Option<String>,
     /// `PUNKTFUNK_GAMESTREAM` — enable the GameStream/Moonlight-compat planes (nvhttp pairing,
     /// RTSP, ENet control, `_nvstream` mDNS) from `host.env`, equivalent to the `--gamestream`
     /// CLI flag (either source turns it on). **Default OFF** — the secure native-only host: the
@@ -374,6 +398,14 @@ impl HostConfig {
             host_name: val("PUNKTFUNK_HOST_NAME")
                 .map(|s| s.trim().to_string())
                 .filter(|s| !s.is_empty()),
+            // Blank-is-unset, like `host_name` above: an operator who comments a value out by
+            // emptying it (`PUNKTFUNK_MGMT_BIND=`) means "default", not "parse the empty string".
+            mgmt_bind: val("PUNKTFUNK_MGMT_BIND")
+                .map(|s| s.trim().to_string())
+                .filter(|s| !s.is_empty()),
+            native_port: val("PUNKTFUNK_NATIVE_PORT")
+                .map(|s| s.trim().to_string())
+                .filter(|s| !s.is_empty()),
             // Default OFF, explicit-on grammar: the Moonlight-compat planes are opt-in
             // everywhere (see the field doc); `--gamestream` on the CLI also turns them on.
             gamestream: env_on("PUNKTFUNK_GAMESTREAM").unwrap_or(false),

crates/pf-presenter/src/run.rs

@@ -39,6 +39,14 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 use std::time::{Duration, Instant};
 
+/// [`SessionOpts::on_connected`]'s callback: the host's certificate fingerprint, then the
+/// management-API port from its `Welcome` (`0` = it advertised none).
+///
+/// A named type rather than the inline `Box<dyn FnMut(...)>` because adding the second parameter
+/// tipped it over `clippy::type_complexity` — factoring it out is what that lint asks for, and it
+/// gives the two positional arguments somewhere to be documented.
+pub type ConnectedFn = Box<dyn FnMut([u8; 32], u16)>;
+
 pub struct SessionOpts {
     pub window_title: String,
     /// Start fullscreen (gamescope / `--fullscreen`).
@@ -84,9 +92,14 @@ pub struct SessionOpts {
     pub allow_vrr: bool,
     /// Emit the `{"ready":true}` stdout line after the first presented frame.
     pub json_status: bool,
-    /// Called once on `Connected` with the host's fingerprint (trust persistence is the
-    /// binary's business — this loop stays store-agnostic).
-    pub on_connected: Option<Box<dyn FnMut([u8; 32])>>,
+    /// Called once on `Connected` with the host's fingerprint and the management-API port the
+    /// host reported in its `Welcome` (`0` = it advertised none). Trust persistence is the
+    /// binary's business — this loop stays store-agnostic.
+    ///
+    /// The port rides along because this is the one moment a client is guaranteed to have it
+    /// WITHOUT mDNS: the session it just authenticated carries it. A client that saves it here
+    /// can browse the library of a host it has only ever reached by address.
+    pub on_connected: Option<ConnectedFn>,
     /// The console-UI overlay (§6.1) — `None` is the Skia-free power-user build (stats
     /// stay stdout-only). An overlay whose `init` fails degrades to `None` with a
     /// warning rather than killing the session. Browse mode requires one.
@@ -1377,9 +1390,13 @@ fn run_inner(mut opts: SessionOpts, mut mode: ModeCtl) -> Result<Option<Outcome>
                     apply_capture(&mut window, &mouse, true, cap.desktop(), inhibit_shortcuts);
                     st.capture = Some(cap);
                     st.cursor_chan = Some(crate::cursor::CursorChannel::new(&c));
+                    // Read the mgmt port BEFORE `c` is moved into `st` — the Welcome's answer to
+                    // "where is this host's library", which the binary persists so it survives
+                    // without ever needing an mDNS advert.
+                    let mgmt_port = c.mgmt_port();
                     st.connector = Some(c);
                     if let Some(f) = opts.on_connected.as_mut() {
-                        f(fingerprint);
+                        f(fingerprint, mgmt_port);
                     }
                     if let Some(o) = overlay.as_mut() {
                         o.session_phase(SessionPhase::Streaming);

crates/punktfunk-core/src/abi.rs

@@ -3826,6 +3826,42 @@ fn build_clip_event(
     out
 }
 
+/// The host's management-API port, from this session's `Welcome` — where its game library is
+/// served (distinct from the streaming ports). `0` means the host did not advertise one: an older
+/// host, or the standalone `punktfunk1-host` binary, which has no management API. Treat `0` as
+/// "unknown" and fall back to your own default (47990), never as a port to dial.
+///
+/// This exists so a client does NOT need mDNS to find the library. The port used to live only in
+/// the host's mDNS TXT, so a host that had moved it off 47990 — the supported way to coexist with
+/// a Sunshine fork, whose web UI owns that port — was reachable only where multicast worked. Read
+/// this after connect and prefer it over any cached or default value. Safe any time after connect.
+///
+/// # Safety
+/// `c` is a valid connection handle; `port` is writable (NULL is skipped).
+#[cfg(feature = "quic")]
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn punktfunk_connection_mgmt_port(
+    c: *const PunktfunkConnection,
+    port: *mut u16,
+) -> PunktfunkStatus {
+    guard(|| {
+        // SAFETY: per the ABI contract - an opaque handle from a `*_new`/`*_pair` that the caller
+        // has not yet freed, or null, which `as_ref` reports as `None` and the `match` handles.
+        let c = match unsafe { c.as_ref() } {
+            Some(c) => c,
+            None => return PunktfunkStatus::NullPointer,
+        };
+        // SAFETY: per the ABI contract - the out-param is OPTIONAL, so it is null-checked before
+        // it is written; a non-null one is a caller-owned writable slot.
+        unsafe {
+            if !port.is_null() {
+                *port = c.inner.mgmt_port();
+            }
+        }
+        PunktfunkStatus::Ok
+    })
+}
+
 /// The host capability bitfield the session's `Welcome` carried — a bitfield of
 /// `PUNKTFUNK_HOST_CAP_GAMEPAD_STATE` / `PUNKTFUNK_HOST_CAP_CLIPBOARD` /
 /// `PUNKTFUNK_HOST_CAP_PEN`. A client tests `caps & PUNKTFUNK_HOST_CAP_CLIPBOARD` to decide

crates/punktfunk-core/src/client/control.rs

@@ -73,4 +73,8 @@ pub(crate) struct Negotiated {
     /// [`crate::quic::HOST_CAP_GAMEPAD_STATE`], [`crate::quic::HOST_CAP_CLIPBOARD`]. Exposed to the
     /// embedder via [`NativeClient::host_caps`] so a native client greys out unsupported toggles.
     pub(crate) host_caps: u8,
+    /// The host's management-API port ([`crate::quic::Welcome::mgmt_port`]), `0` when it did not
+    /// advertise one. Surfaced to the embedder via [`crate::NativeClient::mgmt_port`] so a client
+    /// can reach the game library without ever having seen an mDNS advert.
+    pub(crate) mgmt_port: u16,
 }

crates/punktfunk-core/src/client/mod.rs

@@ -268,6 +268,9 @@ pub struct NativeClient {
     /// The host capability bitfield ([`crate::quic::Welcome::host_caps`]) — see
     /// [`NativeClient::host_caps`].
     pub host_caps: u8,
+    /// The host's management-API port ([`crate::quic::Welcome::mgmt_port`]), or `0` when the host
+    /// did not advertise one — see [`NativeClient::mgmt_port`].
+    pub mgmt_port: u16,
     /// Speed-test accumulator, shared with the data-plane pump + control task.
     probe: Arc<Mutex<ProbeState>>,
     shutdown: Arc<AtomicBool>,
@@ -723,6 +726,7 @@ impl NativeClient {
             next_xfer_id: AtomicU32::new(1),
             pen_seq: AtomicU16::new(0),
             host_caps: negotiated.host_caps,
+            mgmt_port: negotiated.mgmt_port,
             probe,
             shutdown,
             end_reason,
@@ -1378,6 +1382,18 @@ impl NativeClient {
         self.host_caps
     }
 
+    /// The host's management-API port, from this session's [`crate::quic::Welcome`] — where its
+    /// game library is served. `0` when the host did not advertise one (an older host, or the
+    /// standalone `punktfunk1-host` binary, which has no management API); the caller then keeps
+    /// its own default.
+    ///
+    /// This is the mDNS-free answer to "where is the library": it arrives over the connection the
+    /// client has already authenticated, so a host reached by IP over a VPN — or on any network
+    /// where multicast never worked — no longer has to be assumed to be on 47990.
+    pub fn mgmt_port(&self) -> u16 {
+        self.mgmt_port
+    }
+
     /// Enable or disable the shared clipboard for this session (`design/clipboard-and-file-transfer.md`
     /// §3.1). Opt-in: nothing is announced or served until this crosses with `enabled = true`.
     /// `flags` carries [`crate::quic::CLIP_FLAG_FILES`]. Non-blocking; the host replies with a

crates/punktfunk-core/src/client/pump/handshake.rs

@@ -255,6 +255,7 @@ pub(super) async fn connect_and_handshake(args: &WorkerArgs) -> Result<Handshake
                 codec: welcome.codec,
                 shard_payload: welcome.shard_payload,
                 host_caps: welcome.host_caps,
+                mgmt_port: welcome.mgmt_port,
             },
             welcome.host_caps,
         ))

crates/punktfunk-core/src/lib.rs

@@ -176,7 +176,16 @@ pub use stats::Stats;
 /// is unchanged (it simply keeps the double-arm race the pair exists to close). Additive and
 /// client-local: nothing new goes on the wire — the width is computed from frame indices the client
 /// already receives — so [`WIRE_VERSION`] is unchanged.
-pub const ABI_VERSION: u32 = 19;
+/// v20: `punktfunk_connection_mgmt_port` — reads the host's management-API port out of the
+/// session's `Welcome`, so a client can find the game library WITHOUT mDNS. The port previously
+/// existed only in the host's mDNS TXT, which made a host that had moved it off 47990 (the
+/// supported way to share a machine with a Sunshine fork, whose web UI owns that port) reachable
+/// only where multicast worked — over a VPN, a routed subnet, or for a host added by IP, the
+/// library silently fell back to a port nothing was listening on. A NEW symbol, not a widened one:
+/// every existing function keeps its signature and behaviour, and an embedder that never calls it
+/// is unchanged. The `Welcome` grew a trailing field, which older peers skip in both directions
+/// (see `Welcome::encode`), so [`WIRE_VERSION`] is unchanged.
+pub const ABI_VERSION: u32 = 20;
 
 /// The punktfunk/1 **wire** version — what `Hello`/`Welcome` carry and hosts equality-check.
 /// Deliberately its own constant: [`ABI_VERSION`] tracks the embeddable **C surface**

crates/punktfunk-core/src/quic/caps.rs

@@ -340,6 +340,7 @@ mod tests {
             audio_channels: 2,
             codec: CODEC_HEVC,
             host_caps: HOST_CAP_GAMEPAD_STATE | HOST_CAP_CLIPBOARD,
+            mgmt_port: 0,
             cipher: 0,
             key_chacha: None,
         };

crates/punktfunk-core/src/quic/handshake.rs

@@ -211,6 +211,22 @@ pub struct Welcome {
     /// advertised, so an unknown id reaching us is a bug, and falling back would yield an
     /// undecryptable session with a confusing failure signature.
     pub cipher: u8,
+    /// The host's management-API port — where its game library is served, distinct from every
+    /// other port here (`udp_port` is the data plane; the control plane is the QUIC port the
+    /// client already dialed). `0` = not advertised (an older host), and the client falls back to
+    /// the compiled-in 47990.
+    ///
+    /// **Why this is on the wire at all:** the port was previously discoverable ONLY from the
+    /// mDNS `mgmt` TXT. A host that moved it off 47990 — the supported way to share a machine with
+    /// a Sunshine fork, whose web UI owns that port — therefore had a working library only where
+    /// multicast worked. Carrying it in the `Welcome` means the client learns it over the
+    /// connection it has already authenticated, so a VPN-only, routed-subnet or manually-added
+    /// host needs no discovery at all.
+    ///
+    /// Appended AFTER the cipher block (offset 69, or 101 when a ChaCha key precedes it) rather
+    /// than at the next free fixed offset, and emitting it forces the `cipher` placeholder — see
+    /// the note in [`Welcome::encode`]. `0` when an older host omitted it.
+    pub mgmt_port: u16,
     /// The 256-bit ChaCha20-Poly1305 session key (RFC 8439 requires the full 32 bytes; wire
     /// cost is once per handshake) — present iff `cipher == 1`, at offsets 69..101. The legacy
     /// 16-byte `key` keeps its offset and stays independently random, so nothing downstream
@@ -473,11 +489,24 @@ impl Welcome {
             self.key_chacha.is_some(),
             "key_chacha present iff cipher == 1"
         );
-        if self.cipher != CIPHER_AES_128_GCM {
+        //
+        // ⚠ `mgmt_port` follows the cipher block, so emitting it FORCES the cipher byte even for
+        // an AES session — the placeholder discipline `Hello::encode` already uses for
+        // `audio_channels`/`preferred_codec`. Without that, an AES Welcome carrying a mgmt port
+        // would put the port's low byte at offset 68, exactly where every 0.28.x client reads
+        // `cipher` — and that decode is deliberately fail-closed on an unknown id, so the whole
+        // handshake would break against currently-shipped clients. An explicit `cipher = 0` is
+        // harmless by comparison: a current client reads AES (correct), and a pre-cipher client
+        // stops before 68 regardless.
+        let mgmt_present = self.mgmt_port != 0;
+        if self.cipher != CIPHER_AES_128_GCM || mgmt_present {
             b.push(self.cipher);
             if let Some(k) = &self.key_chacha {
                 b.extend_from_slice(k);
             }
+            if mgmt_present {
+                b.extend_from_slice(&self.mgmt_port.to_le_bytes());
+            }
         }
         b
     }
@@ -488,9 +517,12 @@ impl Welcome {
         // salt[45..49] frames[49..53] compositor[53] gamepad[54] bitrate_kbps[55..59]
         // bit_depth[59] color.primaries[60] color.transfer[61] color.matrix[62] color.range[63]
         // chroma_format[64] audio_channels[65] codec[66] host_caps[67] cipher[68]
-        // key_chacha[69..101] (everything from compositor on is an optional trailing byte; an
-        // older host stops earlier; cipher/key_chacha are present only when ChaCha was
-        // negotiated).
+        // key_chacha[69..101] mgmt_port[69..71 | 101..103] (everything from compositor on is an
+        // optional trailing byte; an older host stops earlier; cipher/key_chacha are present only
+        // when ChaCha was negotiated). `mgmt_port` is the one field whose offset is NOT fixed: it
+        // follows the cipher block, so it starts at 69 for an AES session and 101 when a 32-byte
+        // ChaCha key precedes it. Emitting it forces the cipher byte (see `encode`), so "cipher
+        // absent" and "mgmt_port present" can never both hold.
         if b.len() < 53 || &b[0..4] != MAGIC {
             return Err(PunktfunkError::InvalidArg("bad Welcome"));
         }
@@ -518,6 +550,18 @@ impl Welcome {
             }
             _ => return Err(PunktfunkError::InvalidArg("bad Welcome")),
         };
+        // The mgmt port sits after the cipher block, so its offset depends on whether a ChaCha key
+        // preceded it. Absent (an older host, or one that did not advertise) → `0` = unknown, and
+        // the client falls back to the compiled-in default.
+        let mgmt_off = if cipher == CIPHER_CHACHA20_POLY1305 {
+            101
+        } else {
+            69
+        };
+        let mgmt_port = b
+            .get(mgmt_off..mgmt_off + 2)
+            .map(|s| u16::from_le_bytes(s.try_into().unwrap()))
+            .unwrap_or(0);
         Ok(Welcome {
             abi_version: u32at(4),
             udp_port: u16at(8),
@@ -585,6 +629,7 @@ impl Welcome {
             // Optional trailing host-caps byte — absent on an older host → 0 (no gamepad-state
             // snapshots; the client keeps sending legacy per-transition events).
             host_caps: b.get(67).copied().unwrap_or(0),
+            mgmt_port,
             cipher,
             key_chacha,
         })
@@ -671,6 +716,7 @@ mod tests {
             audio_channels: 2,
             codec: CODEC_H264, // exercise a non-default codec through the roundtrip
             host_caps: HOST_CAP_GAMEPAD_STATE,
+            mgmt_port: 0,
             cipher: 0,
             key_chacha: None,
         };
@@ -736,6 +782,7 @@ mod tests {
             audio_channels: 2,
             codec: CODEC_HEVC,
             host_caps: 0,
+            mgmt_port: 0,
             cipher: CIPHER_AES_128_GCM,
             key_chacha: None,
         };
@@ -779,6 +826,48 @@ mod tests {
         let cha_cfg = cha.session_config(Role::Client);
         assert_eq!(cha_cfg.key, SessionKey::ChaCha20Poly1305(k32));
         cha_cfg.validate().expect("ChaCha config validates");
+
+        // ── mgmt_port, the trailing field after the cipher block ──────────────────────────────
+        //
+        // ⚠ THE HAZARD THIS PINS: `mgmt_port` follows `cipher`, and `cipher` is emitted only when
+        // non-default. Appending the port to an AES Welcome without forcing the cipher byte would
+        // land the port's LOW BYTE at offset 68 — exactly where every shipped client reads
+        // `cipher`, whose decode is fail-closed on an unknown id. 47991 is 0xBB57, so byte 68
+        // would read 0x57 = 87, an unknown id, and EVERY 0.28.x client would fail the handshake
+        // against a host that had merely moved its mgmt port. Assert the placeholder is there.
+        let mgmt = Welcome {
+            mgmt_port: 47991,
+            ..base
+        };
+        let menc = mgmt.encode();
+        assert_eq!(menc.len(), 68 + 1 + 2, "cipher placeholder + LE u16 port");
+        assert_eq!(
+            menc[68], CIPHER_AES_128_GCM,
+            "the cipher byte MUST be present (as 0) so a current client still reads AES here"
+        );
+        assert_eq!(&menc[69..71], &47991u16.to_le_bytes());
+        assert_eq!(Welcome::decode(&menc).unwrap(), mgmt);
+
+        // With ChaCha the port sits after the 32-byte key instead, at 101..103.
+        let both = Welcome {
+            mgmt_port: 47991,
+            cipher: CIPHER_CHACHA20_POLY1305,
+            key_chacha: Some(k32),
+            ..base
+        };
+        let benc = both.encode();
+        assert_eq!(benc.len(), 68 + 1 + 32 + 2);
+        assert_eq!(&benc[101..103], &47991u16.to_le_bytes());
+        assert_eq!(Welcome::decode(&benc).unwrap(), both);
+
+        // A host that advertises no mgmt port emits nothing extra — an AES Welcome stays exactly
+        // 68 bytes, so this field costs the common case zero and cannot perturb an old client.
+        assert_eq!(base.encode().len(), 68);
+        // ...and an old host's Welcome decodes to 0 = unknown, never to a port we might dial.
+        assert_eq!(Welcome::decode(&enc).unwrap().mgmt_port, 0);
+        assert_eq!(Welcome::decode(&cenc).unwrap().mgmt_port, 0);
+        // A truncated tail (one byte of the port) is not half a port: it reads as unknown.
+        assert_eq!(Welcome::decode(&menc[..70]).unwrap().mgmt_port, 0);
     }
 
     #[test]
@@ -873,6 +962,7 @@ mod tests {
                 audio_channels: 2,
                 codec: CODEC_PYROWAVE,
                 host_caps: 0,
+                mgmt_port: 0,
                 cipher: 0,
                 key_chacha: None,
             }
@@ -947,6 +1037,7 @@ mod tests {
                 audio_channels: 2,
                 codec: CODEC_H264,
                 host_caps: 0,
+                mgmt_port: 0,
                 cipher: 0,
                 key_chacha: None,
             }
@@ -1058,6 +1149,7 @@ mod tests {
             audio_channels: 6, // 5.1 — exercises the non-default trailing byte
             codec: CODEC_HEVC,
             host_caps: HOST_CAP_GAMEPAD_STATE,
+            mgmt_port: 0,
             cipher: 0,
             key_chacha: None,
         };

crates/punktfunk-host/src/audio/linux/mod.rs

@@ -682,6 +682,10 @@ fn pw_thread(
     use pw::{properties::properties, spa};
     use spa::param::audio::{AudioFormat, AudioInfoRaw};
     use spa::pod::Pod;
+    // The stream's `process` callbacks run ON this mainloop thread (we never hand PipeWire a
+    // separate data loop), so PipeWire's own client `module-rt` boost of its data loops does not
+    // cover it — the ~2.7 ms capture quantum lives or dies by this thread's scheduling.
+    pf_frame::thread_qos::boost_thread_priority(true);
 
     // Setup errors funnel through the ready handshake (mirrors mic_pw_thread's IIFE).
     let result = (|| -> Result<()> {

crates/punktfunk-host/src/main.rs

@@ -761,6 +761,9 @@ fn parse_serve(args: &[String]) -> Result<(mgmt::Options, native::NativeServe, b
     // paired clients can browse the game library out of the box (the bearer admin surface stays
     // loopback-gated in `mgmt::require_auth` regardless of the bind).
     let mut mgmt_bind_explicit = false;
+    // Same question for the native port: an explicit `--native-port` out-ranks
+    // `PUNKTFUNK_NATIVE_PORT` from host.env, resolved after the loop.
+    let mut native_port_explicit = false;
     let mut i = 0;
     while i < args.len() {
         let arg = args[i].as_str();
@@ -793,7 +796,8 @@ fn parse_serve(args: &[String]) -> Result<(mgmt::Options, native::NativeServe, b
             "--native-port" => {
                 native_port = next()?
                     .parse()
-                    .map_err(|_| anyhow::anyhow!("bad --native-port (want a port number)"))?
+                    .map_err(|_| anyhow::anyhow!("bad --native-port (want a port number)"))?;
+                native_port_explicit = true;
             }
             "--data-port" => {
                 data_port = Some(
@@ -844,9 +848,34 @@ fn parse_serve(args: &[String]) -> Result<(mgmt::Options, native::NativeServe, b
     // default". This only LAN-exposes the read-only cert allowlist; the bearer-token admin surface
     // is confined to loopback peers in `mgmt::require_auth`, so binding wide adds no admin exposure.
     // An operator who pinned `--mgmt-bind` (e.g. `127.0.0.1:47990` to restore loopback-only) keeps it.
+    //
+    // Same two-source shape as `--gamestream` / `PUNKTFUNK_GAMESTREAM` below, and for the same
+    // reason: the packaged units ship a fixed ExecStart, so `host.env` is the only route a package
+    // user has to move this that an upgrade won't overwrite. CLI wins — it is the more explicit of
+    // the two and the one a support instruction reaches for.
     if !mgmt_bind_explicit {
-        opts.bind = std::net::SocketAddr::from(([0, 0, 0, 0], mgmt::DEFAULT_PORT));
+        opts.bind = match pf_host_config::config().mgmt_bind.as_deref() {
+            Some(s) => s
+                .parse()
+                .map_err(|_| anyhow::anyhow!("bad PUNKTFUNK_MGMT_BIND '{s}' (want IP:PORT)"))?,
+            None => std::net::SocketAddr::from(([0, 0, 0, 0], mgmt::DEFAULT_PORT)),
+        };
     }
+    // Same two-source resolution as the mgmt bind above. A bad value is FATAL rather than ignored:
+    // silently serving on 9777 while host.env says otherwise is the failure that reads as "I moved
+    // the port and the client still can't reach me".
+    if !native_port_explicit {
+        if let Some(s) = pf_host_config::config().native_port.as_deref() {
+            native_port = s
+                .parse()
+                .map_err(|_| anyhow::anyhow!("bad PUNKTFUNK_NATIVE_PORT '{s}' (want a port)"))?;
+        }
+    }
+    // Publish the resolved port for the console, right here rather than inside `serve`: the
+    // console's unit gates on `mgmt-token` (persisted a few lines above), so writing the endpoint
+    // in the same function keeps the two files effectively simultaneous. A console that still wins
+    // that race falls back to 47990 and its `Restart=always` retry picks the file up.
+    mgmt::publish_endpoint(opts.bind);
     let native = native::NativeServe {
         port: native_port,
         require_pairing: !open,
@@ -999,10 +1028,13 @@ USAGE:
     punktfunk-host spike [OPTIONS]            capture→encode→file pipeline spike (dev tool)
 
 SERVE OPTIONS:
-    --mgmt-bind <IP:PORT>        management API address (default: 0.0.0.0:47990 — paired clients
+    --mgmt-bind <IP:PORT>        management API address (or PUNKTFUNK_MGMT_BIND in host.env, which
+                                 this flag overrides). Default: 0.0.0.0:47990 — paired clients
                                  reach the read-only surface, incl. the game library, over mTLS;
                                  the bearer admin API stays loopback-only. Pin 127.0.0.1:47990 to
-                                 bind loopback only)
+                                 bind loopback only. Move the PORT (e.g. 0.0.0.0:47991) to share a
+                                 machine with Sunshine/Apollo/Vibeshine, whose web UI owns 47990 —
+                                 clients follow via mDNS and the console via mgmt-endpoint
     --mgmt-token <TOKEN>         bearer token for the management API (or PUNKTFUNK_MGMT_TOKEN); the
                                  admin endpoints it guards are honored only from a loopback peer
                                  (the co-located web console), never over the LAN
@@ -1013,7 +1045,9 @@ SERVE OPTIONS:
                                  Also PUNKTFUNK_GAMESTREAM=1 in host.env (how a packaged install
                                  opts in — the shipped units run native-only)
     --native                     no-op (the native punktfunk/1 plane always runs in `serve` now)
-    --native-port <PORT>         native QUIC port (default 9777)
+    --native-port <PORT>         native QUIC port (or PUNKTFUNK_NATIVE_PORT in host.env, which
+                                 this flag overrides). Default 9777. Clients follow via mDNS, and
+                                 a manually-added host keeps whatever port it was added with
     --data-port <PORT>           pin the per-session video data plane to this fixed UDP port and
                                  stream direct (no hole-punch) — open exactly this port in a host
                                  firewall to avoid the ~2.5 s punch-timeout. Default (unset) or

crates/punktfunk-host/src/mgmt.rs

@@ -57,8 +57,98 @@ pub(crate) use plugins::ui_credential;
 
 /// Default management port — adjacent to the GameStream block (47984…48010), and the same
 /// number Sunshine users already associate with "the config UI".
+///
+/// ⚠ That last part is also why it is the ONE port a Sunshine fork and a GameStream-off Punktfunk
+/// still collide on (47990 is their web UI). Moving it is supported — see [`publish_endpoint`] and
+/// `PUNKTFUNK_MGMT_BIND` — and every consumer derives the real port rather than assuming this one.
 pub const DEFAULT_PORT: u16 = 47990;
 
+/// The file [`publish_endpoint`] writes the effective mgmt URL to, next to `mgmt-token`.
+const ENDPOINT_FILE: &str = "mgmt-endpoint";
+
+/// The port the management API actually bound, recorded once by [`publish_endpoint`].
+static EFFECTIVE_PORT: std::sync::OnceLock<u16> = std::sync::OnceLock::new();
+
+/// The mgmt port this process is serving on, or `0` when there is no management API at all — the
+/// standalone `punktfunk1-host` binary, which never calls [`publish_endpoint`].
+///
+/// The native handshake reads this to put the port in every session's `Welcome`, so a client learns
+/// it over the connection it has already authenticated instead of needing the mDNS advert. Resolved
+/// ONCE, from the same value the endpoint file carries, so the wire, the file and the advert cannot
+/// disagree — the whole point of this being a lookup rather than a fourth place to compute a port.
+///
+/// ⚠ `0` matters: advertising 47990 from a host with no mgmt API would point clients at a port
+/// nothing is listening on, which is strictly worse than saying nothing and letting them fall back.
+pub fn effective_port() -> u16 {
+    EFFECTIVE_PORT.get().copied().unwrap_or(0)
+}
+
+/// Publish the mgmt API's *effective* loopback URL to `<config-dir>/mgmt-endpoint`, in the same
+/// `KEY=VALUE` form as `mgmt-token` so the bundled console can source it directly as a systemd
+/// `EnvironmentFile` (and `windows::service::spawn_web` can read it with `read_env_file_value`).
+///
+/// **Why this exists:** the port used to be a literal `47990` in five places — this constant, the
+/// Windows service's console launch, `scripts/punktfunk-web.service`, the NixOS module, and the
+/// console's own default. Moving the listener therefore silently broke the console, because nothing
+/// downstream had any way to learn the new port. Now the host is the single source of truth and
+/// publishes what it actually bound; consumers keep a 47990 fallback purely so an OLD host with a
+/// NEW console still works.
+///
+/// Always loopback, never `bind`'s own address: the console proxies over loopback by design (see
+/// the module docs — the bearer-token admin surface is confined to loopback peers), so a wide
+/// `0.0.0.0` bind must not be echoed here as a LAN URL.
+///
+/// Best-effort: a console that cannot read this simply falls back to 47990, which is strictly what
+/// it did before, so a write failure must not stop the host from serving.
+pub fn publish_endpoint(bind: SocketAddr) {
+    // Record it for [`effective_port`] BEFORE the write: the native handshake reads that to put the
+    // port in every Welcome, and a failed file write must not also cost us the in-band answer.
+    let _ = EFFECTIVE_PORT.set(bind.port());
+    let dir = pf_paths::config_dir();
+    if let Err(e) = pf_paths::create_private_dir(&dir) {
+        tracing::warn!(error = %e, "could not create the config dir to publish the mgmt endpoint");
+        return;
+    }
+    match write_endpoint(&dir, bind.port()) {
+        Ok(path) => {
+            tracing::debug!(path = %path.display(), port = bind.port(), "published mgmt endpoint")
+        }
+        Err(e) => tracing::warn!(
+            dir = %dir.display(),
+            error = %e,
+            "could not publish the mgmt endpoint — a console on another port will fall back to 47990"
+        ),
+    }
+}
+
+/// The IO half of [`publish_endpoint`], taking the directory so it is testable without touching
+/// `PUNKTFUNK_CONFIG_DIR` (which every other test in this process shares).
+///
+/// Deliberately NOT `pf_paths::write_secret_file`: this is not a secret — the same port is already
+/// in the mDNS TXT record — and locking it to SYSTEM/Administrators on Windows would keep a
+/// user-session console from reading the very thing it is published for. The 0700 config dir is the
+/// access control that matters.
+fn write_endpoint(dir: &std::path::Path, port: u16) -> std::io::Result<std::path::PathBuf> {
+    let path = dir.join(ENDPOINT_FILE);
+    // Write-then-rename rather than a plain truncating write: the console's systemd unit may source
+    // this file at any moment, including while the host is restarting and rewriting it. A torn read
+    // would hand systemd an EMPTY `PUNKTFUNK_MGMT_URL`, which is worse than a missing file — the
+    // built-in default only applies to an UNSET variable, not a set-but-blank one. `rename` over an
+    // existing path is atomic on Unix and replaces on Windows, so a reader sees old or new, never
+    // half. (The consumers treat blank as unset too — this is the belt to that pair of braces.)
+    let tmp = dir.join(format!("{ENDPOINT_FILE}.tmp"));
+    std::fs::write(&tmp, endpoint_line(port))?;
+    std::fs::rename(&tmp, &path)?;
+    Ok(path)
+}
+
+/// The published line. Must stay valid as BOTH a systemd `EnvironmentFile` entry and input to
+/// `windows::service::read_env_file_value` — i.e. exactly one `KEY=VALUE` line, no quoting, and no
+/// `=` inside the value (a URL has none).
+fn endpoint_line(port: u16) -> String {
+    format!("PUNKTFUNK_MGMT_URL=https://127.0.0.1:{port}\n")
+}
+
 /// Management server options (CLI: `serve --mgmt-bind ADDR --mgmt-token TOKEN`).
 #[derive(Clone, Debug)]
 pub struct Options {

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

@@ -1,6 +1,42 @@
 //! Handler + auth tests for the management API, exercised through `app()`. Split out of the
 //! `mgmt` facade (plan §W5).
 
+/// The published endpoint line has to satisfy TWO parsers written independently: systemd
+/// (`EnvironmentFile=`) and `windows::service::read_env_file_value`. This pins the shape both need
+/// — one `KEY=VALUE` line — and re-implements the Windows reader's split, so a change to the format
+/// fails here rather than silently pointing the console at the wrong port on the one platform CI
+/// cannot exercise.
+#[test]
+fn published_endpoint_line_parses_the_way_both_consumers_read_it() {
+    let dir = std::env::temp_dir().join(format!(
+        "pf-mgmt-endpoint-{}-{:p}",
+        std::process::id(),
+        &0u8 as *const u8
+    ));
+    std::fs::create_dir_all(&dir).unwrap();
+    let path = super::write_endpoint(&dir, 47991).unwrap();
+    assert_eq!(path.file_name().unwrap(), super::ENDPOINT_FILE);
+
+    let contents = std::fs::read_to_string(&path).unwrap();
+    assert_eq!(contents, "PUNKTFUNK_MGMT_URL=https://127.0.0.1:47991\n");
+
+    // `read_env_file_value`'s exact logic: first non-blank line, split once on '=', take the value.
+    let line = contents
+        .lines()
+        .find(|l| !l.trim().is_empty())
+        .unwrap()
+        .trim();
+    let value = line.split_once('=').map_or(line, |(_, v)| v).trim();
+    assert_eq!(value, "https://127.0.0.1:47991");
+    // The value must survive that split intact — i.e. carry no '=' of its own.
+    assert!(!value.contains('='));
+    // Loopback whatever the listener binds: the console proxies over loopback by design, so a wide
+    // 0.0.0.0 bind must never be echoed here as a LAN URL.
+    assert!(value.starts_with("https://127.0.0.1:"));
+
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
 use super::*;
 use crate::encode::Codec;
 #[cfg(feature = "gamestream")]

crates/punktfunk-host/src/native/audio.rs

@@ -100,6 +100,11 @@ pub(super) fn audio_thread(
     /// pacing exists to prevent — so past this point the debt is forgiven, not repaid.
     const PACE_REANCHOR: std::time::Duration = std::time::Duration::from_millis(100);
     let want = punktfunk_core::audio::normalize_channels(channels);
+    // Same boost the video capture/encode loop takes, and this thread needs it MORE: it paces
+    // 5 ms datagrams, so a scheduling stall here is directly audible where a late video frame
+    // is one presentation slip. The 2026-08-14 field log's stutter was exactly this thread
+    // descheduled by fresh-game-launch shader storms — it carried no priority at all.
+    pf_frame::thread_qos::boost_thread_priority(true);
     // Tier and redundancy are ONE decision, budgeted against the session's video bitrate — see
     // `handshake::audio_budget`. An unparseable `audio.quality` was already warned about there
     // and fell back to the default, so nothing here can silently downgrade someone's audio.

crates/punktfunk-host/src/native/handshake.rs

@@ -658,9 +658,14 @@ pub(super) async fn negotiate(
             } else {
                 0
             },
+        // Where this host serves its game library, so the client never has to have seen an mDNS
+        // advert to find it. `0` on the standalone punktfunk1-host binary (no management API),
+        // and the client then keeps its compiled-in default.
+        mgmt_port: crate::mgmt::effective_port(),
         // The negotiated session AEAD (resolved above) + its 32-byte key toward a ChaCha
         // client; toward everyone else cipher 0 keeps the Welcome byte-identical to the
-        // pre-cipher wire form. The host's own data plane picks the cipher up via
+        // pre-cipher wire form — unless a mgmt port rides along, which forces the cipher
+        // placeholder (see `Welcome::encode`). The host's own data plane picks the cipher up via
         // `welcome.session_config` — no other host change.
         cipher: if chacha {
             punktfunk_core::quic::CIPHER_CHACHA20_POLY1305

crates/punktfunk-host/src/native/pad_audio.rs

@@ -472,6 +472,9 @@ fn pad_audio_thread<C: crate::audio::AudioCapturer>(
     open: impl Fn() -> anyhow::Result<C>,
     stop: Arc<AtomicBool>,
 ) {
+    // Above-normal like the session send thread — this plane is silence-gated and tiny, but when
+    // a pad speaker/haptics stream IS live it runs the same ≤10 ms cadence as session audio.
+    crate::native::boost_thread_priority(false);
     let mut lanes = match build_lanes(kinds) {
         Ok(l) => l,
         Err(e) => {

crates/punktfunk-host/src/windows/service.rs

@@ -1063,13 +1063,22 @@ fn spawn_web(cfg: &WebConfig, data: &Path, job: HANDLE) -> Result<Child> {
         .ok()
         .filter(|v| !v.trim().is_empty())
         .or_else(|| read_env_file_value(&data.join("web-password")));
+    // The mgmt URL resolves env-over-file too, for the same reason the token does — except the file
+    // here is written by `mgmt::publish_endpoint` on every `serve`, so a host moved off 47990 (a
+    // Sunshine fork owns that port as its web UI) carries the console with it instead of leaving it
+    // proxying to a port nothing is listening on. The literal stays only as the last-resort default.
+    let mgmt_url = std::env::var("PUNKTFUNK_MGMT_URL")
+        .ok()
+        .filter(|v| !v.trim().is_empty())
+        .or_else(|| read_env_file_value(&data.join("mgmt-endpoint")))
+        .unwrap_or_else(|| "https://127.0.0.1:47990".into());
 
     let mut overrides: Vec<(&str, String)> = vec![
         ("PORT", "47992".into()),
         ("HOST", "0.0.0.0".into()),
         // The /api proxy hop to the host's loopback HTTPS mgmt API. The host's self-signed cert is
         // accepted only inside the proxy code (per-request TLS), never process-wide.
-        ("PUNKTFUNK_MGMT_URL", "https://127.0.0.1:47990".into()),
+        ("PUNKTFUNK_MGMT_URL", mgmt_url),
         // Serve HTTPS with the host's own identity cert; mark the session cookie Secure.
         (
             "PUNKTFUNK_UI_TLS_CERT",

docs-site/content/docs/configuration.md

@@ -195,6 +195,7 @@ it — leave it or delete it, it makes no difference.
 |---|---|---|
 | `PUNKTFUNK_HOST_NAME` | free text, e.g. `Living Room` | The name this host shows up under in Moonlight and in the Punktfunk clients. Default: the machine's own hostname — so a box called `bazzite-htpc` can present itself as `Living Room` without renaming the machine. Takes effect on host restart. Spaces and accents are fine; `.` becomes `-` (a dot would split the name in client lists) and it's capped at 63 characters. The machine's real hostname is still what the host answers to on the network. |
 | `PUNKTFUNK_MDNS` | `1` · `0` *(default on)* | mDNS adverts (native + GameStream). `0` skips them (same as `--no-mdns`) — for networks/containers where multicast doesn't work; add the host by address in the client instead. |
+| `PUNKTFUNK_NATIVE_PORT` | port *(default: `9777`)* | The native punktfunk/1 (QUIC) control port clients connect on — same as `serve --native-port`, which overrides it. Clients discover the port over mDNS, and a host you added by hand keeps whatever port you added it with, so moving this needs no change on the client. A value that isn't a port is a startup error rather than a silent fall back to 9777. |
 | `PUNKTFUNK_DATA_PORT` | port | Pin the per-session video data plane to a fixed UDP port and stream direct (no hole-punch) — open exactly that port in the host firewall. Same as `serve --data-port`; see [Troubleshooting](/docs/troubleshooting). Default: random port + hole-punch. |
 | `PUNKTFUNK_IDLE_TIMEOUT_MS` | ms (default `8000`) | How long the host waits before declaring a client that vanished (cable pulled, Wi-Fi dropped) gone — which is when a kept virtual display starts its linger. Lower it (e.g. `3000`) to reclaim displays sooner; it's clamped to ≥1 s and the keep-alive scales with it, so a live session never false-disconnects. A deliberate quit is instant regardless. Same as `--idle-timeout-ms` on `punktfunk1-host`. |
 | `PUNKTFUNK_JUMBO` | `1` | Stream in **jumbo frames** — ~9000-byte packets instead of the standard ~1500-byte ones, so a high-bitrate session spends less CPU and per-packet overhead on a wired LAN. Off by default, and safe to turn on: see the note below the table. |
@@ -217,6 +218,7 @@ it — leave it or delete it, it makes no difference.
 | `PUNKTFUNK_MGMT_TOKEN` | token | Bearer token for the management API. If unset it's auto-generated and persisted to `~/.config/punktfunk/mgmt-token` (the bundled web console sources it). Set only to pin a specific token. |
 | `PUNKTFUNK_UI_PASSWORD` | password | Web-console login password. Normally generated on first start and stored in `~/.config/punktfunk/web-password` — see [Forgot your Password?](/docs/forgot-password). |
 | `PUNKTFUNK_PLUGIN_TOKEN` | token | The scoped token the [plugin/scripting runner](/docs/plugins) uses — a narrower credential than `PUNKTFUNK_MGMT_TOKEN`, never full admin. Same precedence: if unset it's generated and persisted to `~/.config/punktfunk/plugin-token`. Set only to pin a specific token. |
+| `PUNKTFUNK_MGMT_BIND` | `IP:PORT` *(default: `0.0.0.0:47990`)* | Where the management API listens. The `--mgmt-bind` flag overrides it. Two reasons to set it: pin `127.0.0.1:47990` to keep the API off the LAN entirely (paired clients then can't browse your library), or **move the port to share the machine with Sunshine, Apollo or Vibeshine** — 47990 is their web UI as well as our management API, and it's the only port the two still share once GameStream compat is off. Everything downstream follows the port you pick: native clients learn it from discovery, and the web console reads it from `~/.config/punktfunk/mgmt-endpoint`, which the host writes on every start. See [another streaming host is installed](/docs/troubleshooting#another-streaming-host-sunshine-apollo--is-installed). |
 | `PUNKTFUNK_CONFIG_DIR` | path | Override the config directory (default `~/.config/punktfunk`) — pairing state, certs, apps.json, captures. |
 | `PUNKTFUNK_UI_PLUGIN_PORT` | port *(default: console port + 1)* | The separate port [plugin](/docs/plugins) UIs are served from. They get their own origin on purpose — a plugin page can never act as *you* on the console. If the console log says this port couldn't be opened (plugin UIs then stay disabled rather than sharing the console's origin), point it at a free port and restart. |
 | `PUNKTFUNK_LIBRARY_ART_ROOTS` | directories, separated like `PATH` (`;` on Windows, `:` on Linux/macOS) | Where the host is allowed to read game artwork from when serving your library. Defaults to sensible platform roots: your home directory on Linux/macOS, and on Windows the users base (`C:\Users`) plus your Steam install, wherever it is. Set it when box art lives somewhere else again — a second drive, a network mount, or a launcher installed outside all of those. Setting it **replaces** the defaults, so list every root you need. The host log's "dropped local art the proxy may not serve" line is this knob's cue: those entries still appear in your library, but their covers stay blank until the root is allowed. |

docs-site/content/docs/troubleshooting.md

@@ -29,6 +29,38 @@ and capture/display glitches.
   If you only want to try Punktfunk without removing the other host, at least make sure the other
   host is fully **stopped** first (they cannot both run at once).
 
+### If you must run both anyway
+
+Still unsupported, and you are on your own for the parts below — but if you keep Punktfunk's
+GameStream compat **off** (the default), the overlap narrows to two things you can move.
+
+1. **The port.** With compat off, the Punktfunk *host* binds only UDP 9777, UDP 5353 and TCP
+   **47990** — the web console is a separate service on 47992/47993, which nothing else wants — and
+   47990 is the only one the other host wants, as its web UI. Whoever starts first takes it; the
+   loser is not symmetric, because Punktfunk treats the failure as fatal and exits (the streaming
+   plane goes with the console), while Sunshine merely loses its config UI. That is why it can look
+   like it "worked until one day it didn't" — it is a boot race, not a setting. Move ours:
+
+   ```sh
+   # ~/.config/punktfunk/host.env
+   PUNKTFUNK_MGMT_BIND=0.0.0.0:47991
+   ```
+
+   Nothing else needs changing: clients learn the port from discovery, and the web console reads it
+   from `~/.config/punktfunk/mgmt-endpoint`, which the host rewrites on every start. A host added
+   manually **by IP address** is the exception — it assumes 47990 and its library will stop loading,
+   so re-add it from discovery. (You can move the other host instead: Sunshine and its forks derive
+   every port from one base setting.)
+
+2. **The display, on Windows.** Punktfunk defaults to an *exclusive* topology — while streaming it
+   disables the other displays so its virtual one is the whole desktop, and re-asserts that every
+   two seconds. Apollo-family forks are virtual-display-driven, so their monitor is what gets
+   switched off, repeatedly. Set `PUNKTFUNK_NO_ISOLATE=1`, or pick a different topology in the web
+   console, before blaming the other host.
+
+To see who currently holds the port: `ss -lptn 'sport = :47990'` on Linux,
+`netstat -ano | findstr :47990` on Windows.
+
 ## The host isn't found on the network
 
 - Make sure the host is actually running — on Linux `systemctl --user status punktfunk-host` (or you

docs/releases/README.md

@@ -54,8 +54,8 @@ no build, no assets on the Gitea release, nothing on Play. Two more checks sit d
 `play-upload.py` refuses text over the 500-char cap (printing the real count) before it uploads,
 because the API only rejects oversized notes at commit, by which point the AAB is already on Play.
 
-Canary is exempt: it has no curated notes, and Play reusing text for internal testers costs
-nothing.
+Canary is exempt: it has no curated notes; open-testing users see the previous release's text on
+a canary, which is cosmetic and cheaper than gating every main push on a notes file.
 
 Same freeze rule as the notes: once the tag exists, this file is the record of what that
 versionCode shipped.

include/punktfunk_core.h

@@ -105,7 +105,16 @@
 // is unchanged (it simply keeps the double-arm race the pair exists to close). Additive and
 // client-local: nothing new goes on the wire — the width is computed from frame indices the client
 // already receives — so [`WIRE_VERSION`] is unchanged.
-#define PUNKTFUNK_ABI_VERSION 19
+// v20: `punktfunk_connection_mgmt_port` — reads the host's management-API port out of the
+// session's `Welcome`, so a client can find the game library WITHOUT mDNS. The port previously
+// existed only in the host's mDNS TXT, which made a host that had moved it off 47990 (the
+// supported way to share a machine with a Sunshine fork, whose web UI owns that port) reachable
+// only where multicast worked — over a VPN, a routed subnet, or for a host added by IP, the
+// library silently fell back to a port nothing was listening on. A NEW symbol, not a widened one:
+// every existing function keeps its signature and behaviour, and an embedder that never calls it
+// is unchanged. The `Welcome` grew a trailing field, which older peers skip in both directions
+// (see `Welcome::encode`), so [`WIRE_VERSION`] is unchanged.
+#define PUNKTFUNK_ABI_VERSION 20
 
 // The punktfunk/1 **wire** version — what `Hello`/`Welcome` carry and hosts equality-check.
 // Deliberately its own constant: [`ABI_VERSION`] tracks the embeddable **C surface**
@@ -3125,6 +3134,22 @@ PunktfunkStatus punktfunk_connection_mode(const PunktfunkConnection *c,
 PunktfunkStatus punktfunk_connection_gamepad(const PunktfunkConnection *c, uint32_t *gamepad);
 #endif
 
+#if defined(PUNKTFUNK_FEATURE_QUIC)
+// The host's management-API port, from this session's `Welcome` — where its game library is
+// served (distinct from the streaming ports). `0` means the host did not advertise one: an older
+// host, or the standalone `punktfunk1-host` binary, which has no management API. Treat `0` as
+// "unknown" and fall back to your own default (47990), never as a port to dial.
+//
+// This exists so a client does NOT need mDNS to find the library. The port used to live only in
+// the host's mDNS TXT, so a host that had moved it off 47990 — the supported way to coexist with
+// a Sunshine fork, whose web UI owns that port — was reachable only where multicast worked. Read
+// this after connect and prefer it over any cached or default value. Safe any time after connect.
+//
+// # Safety
+// `c` is a valid connection handle; `port` is writable (NULL is skipped).
+PunktfunkStatus punktfunk_connection_mgmt_port(const PunktfunkConnection *c, uint16_t *port);
+#endif
+
 #if defined(PUNKTFUNK_FEATURE_QUIC)
 // The host capability bitfield the session's `Welcome` carried — a bitfield of
 // `PUNKTFUNK_HOST_CAP_GAMEPAD_STATE` / `PUNKTFUNK_HOST_CAP_CLIPBOARD` /

packaging/arch/PKGBUILD

@@ -189,7 +189,8 @@ package_punktfunk-host() {
            'mesa' 'libglvnd' 'libxkbcommon' 'wayland'
            'libavcodec.so' 'libavutil.so' 'libavfilter.so' 'libavdevice.so'
            'libavformat.so' 'libswscale.so' 'libswresample.so')
-  optdepends=('pipewire-pulse: PulseAudio-API audio from games/apps (real `pulseaudio` also works)'
+  optdepends=('rtkit: data-plane thread priority without a relogin (else the shipped LimitNICE drop-in applies from next login)'
+              'pipewire-pulse: PulseAudio-API audio from games/apps (real `pulseaudio` also works)'
               'nvidia-utils: NVENC hardware encode + GPU EGL/CUDA zero-copy (REQUIRED to encode on NVIDIA)'
               'gamescope: per-session nested compositor backend (no desktop login needed) — needs >=3.16.22'
               'punktfunk-gamescope: HDR (10-bit BT.2020 PQ) streaming on the gamescope backend — attempted by default when installed'
@@ -235,6 +236,12 @@ package_punktfunk-host() {
   install -Dm0644 "$R/scripts/punktfunk-modules.conf" "$pkgdir/usr/lib/modules-load.d/punktfunk.conf"
   # 32 MB UDP socket buffers (send-side headroom at high bitrate)
   install -Dm0644 "$R/scripts/99-punktfunk-net.conf"  "$pkgdir/usr/lib/sysctl.d/99-punktfunk-net.conf"
+  # Nice-limit headroom for the host's data-plane threads: raises the user-session RLIMIT_NICE so
+  # pf-frame's setpriority() works on boxes without RealtimeKit (with rtkit the host never needs
+  # it). A limit, not a grant — and NEVER a file capability on the host binary (see the KWin
+  # identification note in punktfunk-host.install). Applies from the next login.
+  install -Dm0644 "$R/packaging/linux/50-punktfunk-nice.conf" \
+    "$pkgdir/usr/lib/systemd/system/user@.service.d/50-punktfunk-nice.conf"
   # systemd USER units (the host runs in the graphical session, not as root); repoint ExecStart.
   install -Dm0644 "$R/scripts/punktfunk-host.service" "$pkgdir/usr/lib/systemd/user/punktfunk-host.service"
   sed -i 's#%h/punktfunk/target/release/punktfunk-host#/usr/bin/punktfunk-host#' \

packaging/debian/build-deb.sh

@@ -92,6 +92,11 @@ install -Dm0644 scripts/punktfunk-modules.conf     "$STAGE/usr/lib/modules-load.
 # UDP socket-buffer tuning (32 MB) — without it the kernel clamps the host's SO_SNDBUF to ~416 KB
 # and high-bitrate frames overflow it (send-side packet loss). systemd-sysctl applies it at boot.
 install -Dm0644 scripts/99-punktfunk-net.conf      "$STAGE/usr/lib/sysctl.d/99-punktfunk-net.conf"
+# Nice-limit headroom for the host's data-plane threads: raises the user-session RLIMIT_NICE so
+# pf-frame's setpriority() works on boxes without RealtimeKit (with rtkit the host never needs
+# it). A limit, not a grant, and never a file capability on the host binary (KWin identification).
+install -Dm0644 packaging/linux/50-punktfunk-nice.conf \
+                                                   "$STAGE/usr/lib/systemd/system/user@.service.d/50-punktfunk-nice.conf"
 install -Dm0644 scripts/punktfunk-host.service     "$STAGE/usr/lib/systemd/user/punktfunk-host.service"
 # The source unit's ExecStart points at the dev source tree; a packaged install has the binary at
 # /usr/bin. Rewrite it so a fresh apt install (no hand-rolled unit) starts the installed binary.
@@ -237,6 +242,7 @@ Source: $PKG
 Package: $PKG
 Architecture: any
 Depends: \${shlibs:Depends}
+Recommends: rtkit
 EOF
 # In bundle mode the libav* live in FFMPEG_PREFIX/lib — not a standard loader path, and the
 # target/release binary carries no rpath (only the staged copy does) — so dpkg-shlibdeps can't

packaging/linux/50-punktfunk-nice.conf

@@ -0,0 +1,13 @@
+# Punktfunk: let the streaming host's data-plane threads renice themselves.
+#
+# The host raises its capture/encode/send and audio threads to nice -10/-5 so a CPU-saturating
+# game (or its shader-compile storm at launch) cannot deschedule them mid-stream. That call needs
+# CAP_SYS_NICE or a raised RLIMIT_NICE — and the host binary must never carry a file capability
+# (it would make the process unidentifiable to KWin and kill desktop streaming), so the limit is
+# the right lever. Desktops with RealtimeKit don't need this file (the host falls back to rtkit);
+# it covers rtkit-less installs, from the next login onward.
+#
+# This raises only the LIMIT for user sessions. Nothing is reprioritized by itself: a process
+# still has to call setpriority(), exactly as before.
+[Service]
+LimitNICE=-15

packaging/nix/nixos-module.nix

@@ -497,6 +497,15 @@ in
         group = "root";
       };
 
+      # CPU-side thread priority for the host's data-plane threads (capture/encode/send and the
+      # 5 ms audio loop) rides RealtimeKit: the host asks rtkit to renice the thread when a direct
+      # setpriority() is refused — the same unprivileged broker PipeWire clients use, so nothing
+      # ever enters the host's permitted set and the KWin identification above stays intact.
+      # NixOS is the one distro family where rtkit is not a given, hence the default here;
+      # mkDefault so an operator who runs without rtkit can turn it off (the host then keeps its
+      # pre-0.29 best-effort no-op behaviour, a pacing cost only).
+      security.rtkit.enable = mkDefault true;
+
       systemd.user.services.punktfunk-host = {
         description = "punktfunk GameStream + punktfunk/1 streaming host";
         documentation = [ "https://git.unom.io/unom/punktfunk" ];
@@ -649,7 +658,11 @@ in
         # below went on promising the behaviour it removes.
         unitConfig.StartLimitIntervalSec = 0;
         environment = {
-          PUNKTFUNK_MGMT_URL = "https://127.0.0.1:47990";
+          # PUNKTFUNK_MGMT_URL is deliberately absent: the host publishes the port it actually bound
+          # to ~/.config/punktfunk/mgmt-endpoint (mgmt::publish_endpoint), sourced below, and the
+          # server falls back to https://127.0.0.1:47990 on its own when that file does not exist.
+          # Hardcoding it here would have to out-rank the file, which is a directive-ordering
+          # question in the generated unit — so we simply do not create the conflict.
           PORT = "47992";
           HOST = "0.0.0.0";
           # Serve HTTPS with the host's own identity cert (the anchor native clients already pin) and
@@ -663,6 +676,9 @@ in
           EnvironmentFile = [
             "%h/.config/punktfunk/mgmt-token"
             "-%h/.config/punktfunk/web-password"
+            # The host's effective mgmt URL — see the `environment` note above. Optional: absent on
+            # a host predating mgmt::publish_endpoint, and the server default covers that.
+            "-%h/.config/punktfunk/mgmt-endpoint"
           ];
           ExecStart = "${cfg.web.package}/bin/punktfunk-web-server";
           # `always`, not `on-failure`: a console that exits 0 has still stopped serving, and

packaging/rpm/punktfunk.spec

@@ -123,6 +123,11 @@ Requires:       wireplumber
 # made the host uninstallable for anyone running real PulseAudio, which serves those games just
 # as well. Fedora installs pipewire-pulseaudio by default, so the default box is unaffected.
 Recommends:     pipewire-pulseaudio
+# The data-plane threads renice themselves through RealtimeKit when the direct setpriority() is
+# refused (thread_qos — the host binary can never carry CAP_SYS_NICE, see the %%files note).
+# Weak-dep: Fedora desktops ship rtkit anyway, and without it the user@.service.d LimitNICE
+# drop-in below still covers the direct path from the next login.
+Recommends:     rtkit
 Requires:       opus
 Requires:       libei
 # FFmpeg runtime with NVENC (RPM Fusion). Weak-dep so the package installs even if
@@ -371,6 +376,12 @@ sed -i 's#%h/punktfunk/scripts/headless/run-headless-kde.sh#%{_datadir}/%{name}/
 install -Dm0644 packaging/linux/io.unom.Punktfunk.Host.desktop \
                 %{buildroot}%{_datadir}/applications/io.unom.Punktfunk.Host.desktop
 
+# Scheduling headroom for the host's data-plane threads (see the no-caps note in %%files): raise
+# the user-session nice hard limit so pf-frame's setpriority() also works where RealtimeKit isn't
+# running. A limit, not a grant — takes effect at the user's next login.
+install -Dm0644 packaging/linux/50-punktfunk-nice.conf \
+                %{buildroot}%{_unitdir}/user@.service.d/50-punktfunk-nice.conf
+
 # Status tray: the per-user SNI icon + its XDG autostart entry (self-gating: --autostart exits
 # silently for users who don't run a host) + the hicolor status icons it names.
 install -Dm0755 target/release/punktfunk-tray %{buildroot}%{_bindir}/punktfunk-tray
@@ -526,8 +537,10 @@ install -Dm0644 scripts/punktfunk-scripting.service %{buildroot}%{_userunitdir}/
 # why neither prctl(PR_SET_DUMPABLE, 1) nor systemd AmbientCapabilities= rescues it.
 #
 # The cost of not having it is pacing only: pf-zerocopy walks REALTIME -> HIGH -> default when a
-# priority class is refused, and pf-frame's thread nice is a best-effort no-op. That is exactly
-# how 0.25.0 behaved, which is the behaviour that worked.
+# priority class is refused, and pf-frame's thread nice falls back to RealtimeKit (the same
+# unprivileged broker PipeWire clients use — no capability enters the permitted set, so the KWin
+# identification above is untouched) and to the user@.service.d LimitNICE drop-in shipped below.
+# Only on a box with neither does it remain the best-effort no-op 0.25.0 shipped with.
 #
 # rpm applies file capabilities from package metadata, so a package built WITHOUT %caps() installs
 # the binary with none and an upgrade from 0.26.0-1 clears it — no scriptlet needed.
@@ -553,6 +566,8 @@ install -Dm0644 scripts/punktfunk-scripting.service %{buildroot}%{_userunitdir}/
 # Debugging the WORKER (not the host): a capability makes it AT_SECURE, so the loader ignores
 # LD_LIBRARY_PATH/LD_PRELOAD for it and core dumps are suppressed by default.
 %caps(cap_sys_nice=ep) %{_bindir}/punktfunk-encode-worker
+%dir %{_unitdir}/user@.service.d
+%{_unitdir}/user@.service.d/50-punktfunk-nice.conf
 %{_bindir}/punktfunk-tray
 %{_udevrulesdir}/60-punktfunk.rules
 %dir %{_libexecdir}/punktfunk

scripts/host.env.example

@@ -21,6 +21,21 @@
 # ship a `punktfunk-gamestream` firewalld service / ufw profile for exactly this).
 #PUNKTFUNK_GAMESTREAM=1
 
+# Where the management API listens (default 0.0.0.0:47990). Two uses:
+#   * 127.0.0.1:47990 keeps it off the LAN — at the cost of paired clients browsing your library.
+#   * MOVING THE PORT is how you share a machine with Sunshine/Apollo/Vibeshine: 47990 is their web
+#     UI as well as our management API, and with PUNKTFUNK_GAMESTREAM off it is the ONLY port the
+#     two still share. Nothing else needs editing — clients learn the port from discovery and the
+#     web console reads it from ~/.config/punktfunk/mgmt-endpoint, which the host rewrites on start.
+#   Running two Moonlight-compatible hosts at once is still unsupported; see the troubleshooting
+#   page. On Windows also see PUNKTFUNK_NO_ISOLATE — the display topology is the second conflict.
+#PUNKTFUNK_MGMT_BIND=0.0.0.0:47991
+
+# The native punktfunk/1 (QUIC) control port clients connect on. Default 9777. Clients discover it
+# over mDNS, and a host added by hand keeps whatever port it was added with, so moving this is safe
+# on both sides. A typo here is a startup ERROR rather than a silent fall back to 9777.
+#PUNKTFUNK_NATIVE_PORT=9778
+
 # Video source (GameStream/Moonlight sessions only): `virtual` creates a per-client virtual
 # output at the client's exact resolution+refresh (the flagship mode, and the default);
 # `portal` captures an existing monitor.

scripts/punktfunk-web.service

@@ -25,7 +25,15 @@ Type=simple
 # creates it first, but a manual operator may inject PUNKTFUNK_UI_PASSWORD another way).
 EnvironmentFile=%h/.config/punktfunk/mgmt-token
 EnvironmentFile=-%h/.config/punktfunk/web-password
-Environment=PUNKTFUNK_MGMT_URL=https://127.0.0.1:47990
+# The host's ACTUAL mgmt port: `serve` writes this file (mgmt::publish_endpoint) with the port it
+# really bound, so moving the listener — the fix for sharing a box with a Sunshine fork, which owns
+# 47990 as its web UI — needs no edit here. Optional ('-'): an older host never wrote it, and the
+# server's own built-in default (https://127.0.0.1:47990, util/auth.ts) then applies unchanged.
+#
+# Deliberately NOT paired with an `Environment=PUNKTFUNK_MGMT_URL=` default line: whether a file or
+# an Environment= assignment wins is a question of directive order, and the answer differs between
+# this hand-written unit and the one the NixOS module generates. One source, no precedence puzzle.
+EnvironmentFile=-%h/.config/punktfunk/mgmt-endpoint
 Environment=PORT=47992
 Environment=HOST=0.0.0.0
 # Serve HTTPS (HTTP/1.1 over TLS) with the host's own identity cert; mark the

scripts/steamdeck/install.sh

@@ -313,6 +313,17 @@ if [ "$SUDO_OK" = 1 ]; then
         | sudo tee /etc/sysctl.d/99-punktfunk-net.conf >/dev/null
     sudo sysctl -q -p /etc/sysctl.d/99-punktfunk-net.conf >/dev/null
     ok "UDP socket buffers raised to 32 MB (persisted)"
+    # Nice-limit headroom for the host's data-plane threads (audio/send): without it (or rtkit,
+    # which SteamOS does not guarantee) the per-thread renice silently no-ops and a busy game can
+    # deschedule the 5 ms audio loop. SteamOS's /usr is read-only, so unlike the packaged installs
+    # this lands in /etc — same drop-in, same effect, from the next login. NEVER a file capability
+    # on the host binary (see the setcap note above — KWin identification).
+    if [ -f "$SRC/packaging/linux/50-punktfunk-nice.conf" ]; then
+        sudo install -Dm644 "$SRC/packaging/linux/50-punktfunk-nice.conf" \
+            /etc/systemd/system/user@.service.d/50-punktfunk-nice.conf
+        sudo systemctl daemon-reload || true
+        ok "nice-limit drop-in installed (data-plane thread priority; applies from next login)"
+    fi
     if [ -f "$SRC/scripts/60-punktfunk.rules" ]; then
         sudo install -m644 "$SRC/scripts/60-punktfunk.rules" /etc/udev/rules.d/60-punktfunk.rules
         sudo udevadm control --reload-rules && sudo udevadm trigger || true

web/.env.example

@@ -12,6 +12,12 @@ PUNKTFUNK_UI_PASSWORD=change-me
 # Management API the console proxies to. It serves HTTPS (the host's own identity cert) and
 # requires auth (mTLS or the bearer below). Keep this loopback — the login-gated web server is
 # the only path to it.
+#
+# ON A PACKAGED INSTALL YOU DO NOT SET THIS. The host writes the port it actually bound to
+# ~/.config/punktfunk/mgmt-endpoint in this same KEY=VALUE form, and the shipped units source that
+# file — so a host moved off 47990 (PUNKTFUNK_MGMT_BIND, e.g. to coexist with a Sunshine fork whose
+# web UI owns that port) carries the console with it. This line is for dev, where you run the two
+# halves by hand. Setting it explicitly always wins over the file.
 PUNKTFUNK_MGMT_URL=https://127.0.0.1:47990
 
 # REQUIRED: bearer token for the management API, injected server-side by the /api proxy (never

web/server/util/auth.ts

@@ -105,7 +105,13 @@ export function uiPassword(): string {
  * loopback hop via Bun's per-request `tls` option (routes/api/[...].ts, util/forward.ts). There is
  * deliberately no process-wide NODE_TLS_REJECT_UNAUTHORIZED — see .env.example. */
 export function mgmtUrl(): string {
-	return process.env.PUNKTFUNK_MGMT_URL ?? "https://127.0.0.1:47990";
+	// Blank counts as UNSET, which `??` alone would not do. On a packaged install this value comes
+	// from ~/.config/punktfunk/mgmt-endpoint (written by the host's `serve` with the port it really
+	// bound, so a host moved off 47990 to coexist with a Sunshine fork carries the console with it),
+	// sourced as a systemd EnvironmentFile. An empty or truncated file would otherwise set the
+	// variable to "" and send every proxy hop to a URL that cannot parse.
+	const url = process.env.PUNKTFUNK_MGMT_URL?.trim();
+	return url ? url : "https://127.0.0.1:47990";
 }
 
 /** Bearer token for the management API, injected server-side. */

web/web-run.cmd

@@ -41,6 +41,13 @@ rem Fixed deployment wiring (the Windows analogue of scripts/punktfunk-web.servi
 set "PORT=47992"
 set "HOST=0.0.0.0"
 set "PUNKTFUNK_MGMT_URL=https://127.0.0.1:47990"
+rem ...unless the host published a different one. `serve` writes mgmt-endpoint in the same single
+rem KEY=VALUE form as the token above, carrying the port it ACTUALLY bound - so a host moved off
+rem 47990 (PUNKTFUNK_MGMT_BIND, e.g. to share the box with a Sunshine fork whose web UI owns that
+rem port) brings the console with it. Imported AFTER the default so it wins; absent on an older host,
+rem and then the default above stands.
+set "ENDPOINTFILE=%PFDATA%\mgmt-endpoint"
+if exist "%ENDPOINTFILE%" for /f "usebackq tokens=1* delims==" %%A in ("%ENDPOINTFILE%") do set "%%A=%%B"
 rem No NODE_TLS_REJECT_UNAUTHORIZED: the host's self-signed cert is accepted only for the loopback
 rem proxy hop, scoped inside the proxy code (Bun per-request TLS), not process-wide.
 rem Serve HTTPS (HTTP/1.1 over TLS) with the host's identity cert; mark the session cookie Secure.