Files
punktfunk/CLAUDE.md
T
enricobuehler bfd64ce871
ci / rust (push) Has been cancelled
rename: lumen → punktfunk, everywhere
Full project rename, decided 2026-06-10:
- Crates/binaries: punktfunk-core / punktfunk-host / punktfunk-client-rs.
- C ABI: punktfunk_* symbols, Punktfunk* types, include/punktfunk_core.h,
  PUNKTFUNK_FEATURE_QUIC guard (header regenerated; cbindgen renames updated, incl.
  PUNKTFUNK_BTN_*/PUNKTFUNK_AXIS_* wire constants).
- Protocol: punktfunk/1 — control-plane magic LMN1 → PKF1, nonce salt lmn1 → pkf1.
  WIRE BREAK: clients must be rebuilt from this revision.
- Env knobs: PUNKTFUNK_VIDEO_SOURCE / PUNKTFUNK_COMPOSITOR / PUNKTFUNK_ZEROCOPY / ….
- Host config dir: ~/.config/punktfunk (the box's dir was migrated in place — the
  persistent identity is unchanged, pinned fingerprints stay valid).
- Swift package: PunktfunkKit + PunktfunkCore.xcframework + PunktfunkConnection
  (Sources/PunktfunkClient app + tests renamed with it); build-xcframework.sh updated.
- scripts/: 60-punktfunk.rules, punktfunk-host.service; OpenAPI doc regenerated.

Also: scripts/headless/run-headless-kde.sh — full headless Plasma bringup. Root cause of
"desktop but no apps/settings" over the stream: plasmashell launched without
XDG_MENU_PREFIX=plasma-, so the launcher resolved a nonexistent applications.menu and
rendered an empty menu. The script sets the complete KDE session env (menu prefix,
KDE_FULL_SESSION, session version) and rebuilds ksycoca before starting plasmashell.

Gate: 97/97 tests, clippy -D warnings (both feature sets), fmt, C-ABI harness PASS,
zero lumen references left outside .git.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-10 13:11:59 +00:00

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# CLAUDE.md — punktfunk
Low-latency desktop/game streaming stack, Linux-first, with a shared Rust protocol core
(`punktfunk-core`) exposed over a C ABI and native clients per platform. Full design:
[`docs/implementation-plan.md`](docs/implementation-plan.md). Status table: `README.md`.
## Where the work stands
- **M1 (`punktfunk-core` + C ABI): complete and hardened.** FEC recovery, loopback-under-loss,
proptests, C ABI harness all green; 13 adversarial-review findings fixed +
regression-tested (`a913042`).
- **M2 (GameStream host): working end-to-end with a stock Moonlight client.** Validated live
on this box: pairing (persists across restarts), serverinfo/applist (app catalog from
`~/.config/punktfunk/apps.json` → each entry picks a compositor + nested command), RTSP, ENet
control, audio, and video at the **client's native resolution and refresh** — the host
creates a per-session virtual output via per-compositor `VirtualDisplay` backends:
**KWin** (`zkde_screencast stream_virtual_output`, needs KWin ≥ 6.5.6 headless; >60 Hz via
custom modes), **gamescope** (spawned headless at WxH@Hz, its PipeWire node captured, needs
gamescope ≥ 3.16.22 — older deadlocks on PipeWire ≥ 1.6), **Mutter** (D-Bus
`RecordVirtual` virtual monitor; validated live on headless GNOME Shell 50, zero-copy).
Performance work landed and measured: GPU **zero-copy** on all paths (tiled dmabuf →
EGL/GL → CUDA; LINEAR dmabuf → **Vulkan bridge** → CUDA → NVENC), auto 2-way NVENC
split-encode above ~1 Gpix/s (5K@240), infinite GOP + RFI keyframes (killed the periodic
freeze), encode|send thread split with `sendmmsg` batching. Stable 240 fps at 5120×1440.
Input: mouse/keyboard (libei via RemoteDesktop portal on KWin/GNOME, gamescope's own EIS
socket, wlr protocols on Sway) and **gamepads** (uinput X-Box-360 pads + rumble
back-channel; validated live — pad created/destroyed with the session). Management REST API +
checked-in OpenAPI doc (`mgmt.rs`).
- **M3 (`punktfunk/1`, the native protocol): full session planes, validated live.** QUIC
control plane (`punktfunk-core` `quic` feature: Hello{mode}/Welcome{full Config}/Start), data
plane = the hardened M1 `Session` over raw UDP with **GF(2¹⁶) Leopard FEC + AES-GCM**
(inexpressible in GameStream), host creates the native virtual output at the client's
requested mode. `m3-host` is a **persistent listener** (sessions back to back;
`--max-sessions`). QUIC datagrams carry the side planes, demuxed by first byte: input
0xC8 (incl. **gamepads** — incremental events accumulated into the uinput xpad), **Opus
audio** 0xC9 (48 kHz stereo, 5 ms, host→client), **rumble** 0xCA (host→client). **Trust:**
host serves its persistent identity (`~/.config/punktfunk/cert.pem`, shared with GameStream
pairing) and logs the SHA-256 fingerprint; clients pin it (TOFU on first connect —
`endpoint::client_pinned`). Measured on-box at 720p120: 1680/1680 frames, **p50 0.83 ms**
capture→…→reassembled; audio measured live (~200 pkts/s). `punktfunk-client-rs` is the
working reference client (`--pin`, datagram counters, `--input-test` incl. gamepad).
The embeddable connector (`NativeClient`) exposes it all over the C ABI: `punktfunk_connect`
(pin/TOFU) + `next_au`/`next_audio`/`next_rumble`/`send_input`.
## What's left
1. **M4 — client decode + present: macOS stage 1 done, first light achieved
(2026-06-10).** PunktfunkKit compiles and is tested on macOS (AnnexB → VideoToolbox →
`AVSampleBufferDisplayLayer`, GCMouse/GCKeyboard capture, `PunktfunkClient` app shell);
validated live Mac ↔ this box at 720p60 — vkcube on glass, input injected via gamescope
EIS. Tests: `swift test` in `clients/apple` (unit + real-codec round trip),
`test-loopback.sh` (Swift client vs synthetic m3-host on loopback — runs on macOS),
`RemoteFirstLightTests` (full pipeline over the LAN). See
[`clients/apple/README.md`](clients/apple/README.md). Next: stage 2 presenter
(`VTDecompressionSession` + `CAMetalLayer` frame pacing), glass-to-glass numbers via
`tools/latency-probe` (scaffold), iOS variant. The Linux reference client
(`punktfunk-client-rs`) gets VAAPI + wgpu on the same connector later.
2. **Sub-frame pipelining**: overlap encode and transmit within a frame. Requires a direct
NVENC SDK wrapper (libavcodec only emits whole AUs) — the next big latency lever (~24 ms
at high res).
3. **punktfunk/1 protocol growth**: a PIN-style pairing ceremony on top of fingerprint pinning,
mid-stream mode renegotiation (the Welcome is one-shot today), concurrent sessions
(today: one at a time, extras wait in the accept queue).
4. **M2 polish**: wlroots/Sway `VirtualDisplay` backend (deferred; swaymsg `create_output`),
HDR/10-bit/AV1 negotiation, surround audio, reconnect-at-new-mode robustness.
5. **Native clients** (`clients/{apple,android}` scaffolds) consuming `punktfunk_core.h`.
Box one-time setup is complete: udev rule + `input` group (gamepads validated live),
gamescope 3.16.22 installed system-wide (no PATH override), gnome-shell installed (Mutter
backend validated live). All three compositor backends are live-validated.
## Build / test / run
```sh
cargo build --workspace # green on Linux and macOS
cargo test --workspace # unit + loopback + proptest + C ABI harness (~97 tests)
cargo clippy --workspace --all-targets -- -D warnings
cargo fmt --all --check
cargo run -p loss-harness # FEC loss-resilience sweep (no network needed)
bash crates/punktfunk-core/tests/c/run.sh # standalone C-ABI link + round-trip proof
```
Generated artifacts are **checked in** and CI fails on drift: `include/punktfunk_core.h`
(cbindgen from `punktfunk-core/src/abi.rs`) and `docs/api/openapi.json` (regenerate with
`cargo run -p punktfunk-host -- openapi > docs/api/openapi.json`; spec lives in `mgmt.rs`).
## Layout
```
crates/punktfunk-core/ protocol · FEC · crypto · quic (punktfunk/1 control plane, feature-gated)
crates/punktfunk-host/
gamestream/ Moonlight compat: nvhttp · pairing · rtsp · control · stream · gamepad · apps
vdisplay/{kwin,gamescope,mutter}.rs per-compositor client-sized virtual outputs
zerocopy/{egl,cuda,vulkan}.rs dmabuf → CUDA → NVENC (tiled via EGL/GL, LINEAR via Vulkan)
inject/{libei,wlr,gamepad}.rs input backends (+ uinput virtual gamepads)
capture.rs · encode.rs · audio.rs · m0.rs · m3.rs · mgmt.rs
crates/punktfunk-client-rs/ punktfunk/1 reference client (M3 headless; M4 adds decode+present)
tools/{loss-harness,latency-probe}/ measurement (plan §10)
scripts/ 60-punktfunk.rules · punktfunk-host.service · host.env.example · headless/
include/punktfunk_core.h generated C header
```
## Design invariants — do not regress
- **One core, linked everywhere.** Protocol/FEC/crypto live only in `punktfunk-core`, behind a
stable, versioned C ABI. `tokio`/`quinn` exist only behind the `quic` feature (control
plane); **no async on the per-frame path** — native threads only.
- **Native client resolution, no scaling.** A session gets a virtual output at exactly the
client's WxH@Hz via the `VirtualDisplay` trait (`create(mode) → VirtualOutput { node_id,
remote_fd, preferred_mode, keepalive }`, RAII teardown). There is no cross-compositor
protocol for this — each compositor keeps its own backend.
- **FEC is the wall-breaker.** GF(2⁸) (≤255 shards/block, Moonlight-compatible) and GF(2¹⁶)
Leopard (≤65535 shards/block) — punktfunk/1 negotiates the latter, removing the ~1 Gbps
ceiling.
- **M1 security hardening stays intact**: reassembler bounds attacker-controlled fields
before allocating (`ReassemblerLimits`); AES-GCM per-direction nonce salts + seq-as-AAD;
ABI `struct_size` checks. Regression tests exist — keep them green.
- **PipeWire consumer discipline**: our capture streams set `node.dont-reconnect` and tear
down promptly on negotiation timeout — one wedged link head-blocks the daemon's shared
work queue system-wide.
## Running on this box
Headless QEMU VM (Ubuntu 26.04, kernel 7.0), passthrough RTX 5070 Ti (driver 595 **open**
module — a kernel update silently drops it; reinstall `nvidia-driver-595-open`), no KMS
scanout → KWin `--drm` impossible; everything renders offscreen via `renderD128`.
```sh
# compositor session (shell 1, or the systemd unit in scripts/): full headless Plasma.
# The script sets XDG_MENU_PREFIX=plasma- & co. — without it plasmashell runs but the
# launcher menu is EMPTY (no apps, no System Settings).
bash scripts/headless/run-headless-kde.sh 1920x1080
# host (shell 2):
WAYLAND_DISPLAY=wayland-kde XDG_CURRENT_DESKTOP=KDE PUNKTFUNK_VIDEO_SOURCE=virtual \
PUNKTFUNK_ZEROCOPY=1 cargo run -rp punktfunk-host -- serve
# punktfunk/1 native loopback test (no Moonlight needed; same env as serve, listener persists
# across sessions — bound it with --max-sessions):
cargo run -rp punktfunk-host -- m3-host --source virtual --seconds 10 --max-sessions 1
cargo run -rp punktfunk-client-rs -- --mode 1280x720x120 --out /tmp/a.h265 --input-test # + --pin HEX
```
Pinned crate facts: `ashpd` 0.13 + `pipewire` 0.9 (must match ashpd's) + `ffmpeg-next` 8.x
(system FFmpeg 8 / libavcodec 62). Env knobs: `PUNKTFUNK_VIDEO_SOURCE=virtual|portal`,
`PUNKTFUNK_COMPOSITOR=kwin|gamescope|mutter`, `PUNKTFUNK_ZEROCOPY=1`, `PUNKTFUNK_GAMESCOPE_APP=...`,
`PUNKTFUNK_INPUT_BACKEND=...`, `PUNKTFUNK_PERF=1` (per-stage timing), `PUNKTFUNK_VIDEO_DROP=N` (FEC
test), `PUNKTFUNK_FEC_PCT=N`.
## Conventions
- Rust 2021, `rustfmt` + `clippy -D warnings` clean before commit.
- Match the surrounding code's comment density and naming.
- Commit messages end with the Co-Authored-By trailer (see `git log`).
- `pkill` caution on this box: match exact comm names (`pkill -x gamescope-wl`,
`pkill -x punktfunk-host`) — `pkill -f` self-matches the invoking shell.