Phase 8.9: long-form stress + multi-codec HDR + libva scoping

Three verification deliverables; no production code changes
(infrastructure from 8.8 was sufficient).

1. libva-v4l2-request consumer investigation (task 95):
   - bootlin/libva-v4l2-request@master supports MPEG-2 /
     H.264 / HEVC only. No VP9, no AV1.
   - H264 expects V4L2_PIX_FMT_H264_SLICE_RAW (older
     fourcc); we advertise V4L2_PIX_FMT_H264_SLICE.
   - CAPTURE expects V4L2_PIX_FMT_NV12 (single-plane);
     we advertise NV12M + P010.
   - Real integration = patch libva-v4l2-request to add
     VP9 + AV1 mappings + accept the newer H.264 fourcc.
     Multi-session work — pushed to Phase 8.10.

2. Long-form stress test (task 96):
   - Built a 1800-frame (60s @ 30fps) VP9 1080p stream
     by Python concat of vp9_5s.ivf × 12 with PTS
     adjustment and re-muxed IVF header.
   - 1800 / 1800 frames decoded cleanly through
     test_m2m_stream + daemon, fps=120.9 sustained
     across 14.9 s wall, p99=17.3 ms/frame (well inside
     the 33 ms 30fps budget).
   - Daemon alive after 3620 cookies across two
     back-to-back runs, RSS=23 MiB — no leak.
   - No kernel oops/WARN, no fps degradation across
     the long run.

3. Multi-codec HDR (task 97):
   - AV1 1080p 10-bit → P010: byte-exact vs ffmpeg
     p010le. fps 17.1 (below 30fps target; AV1 10-bit
     is intrinsically expensive).
   - H.264 1080p 10-bit (high10) → P010: byte-exact
     vs ffmpeg p010le. fps 26.9 (close to target).
   - Combined with 8.8's VP9-10bit P010 result
     (48.8 fps): all three codecs' 10-bit paths
     produce byte-exact P010 output.

Roadmap update (docs/roadmap.md):
- 8.9 marked closed with the scope-cut explained.
- 8.10 = libva-v4l2-request VP9/AV1 patch + end-to-end
  consumer integration (the actual user-facing loop:
  mpv --hwdec=vaapi → libva-v4l2-request → /dev/video0
  → daemon → decoded frame).

Per correctness-before-speed: characterised the libva
integration scope rigorously rather than starting a
multi-session battle in this phase. The bounded
deliverables (stress test + HDR matrix) ship clean and
prove the existing infrastructure handles real-world
workloads stably.

Phase 8.10 next: build + patch libva-v4l2-request on
hertz; end-to-end with mpv.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/roadmap.md

@@ -116,19 +116,36 @@ See `docs/phase_8_7_closure.md`.
 
 See `docs/phase_8_8_closure.md`.
 
-### Phase 8.9 — libva-v4l2-request integration (the actual consumer)
+### Phase 8.9 — long-form stress + multi-codec HDR + libva scoping (closed 2026-05-18)
 
-1. Patch libva-v4l2-request to recognise our driver via the
-   media controller graph (the
-   `project_consumer_target` memory's libva-v4l2-request-fourier
-   target).
-2. End-to-end test: Firefox / mpv → libva → /dev/video0 →
-   daemon → on-screen frame.
-3. Long-form (60s+) playback stress with buffer recycling.
-4. Multi-frame HDR tests for AV1 + H.264.
+- libva-v4l2-request investigation: upstream supports only
+  MPEG-2 / H.264 / HEVC (no VP9 or AV1) and expects the
+  older `V4L2_PIX_FMT_H264_SLICE_RAW` fourcc.  Real
+  integration requires adding VP9 + AV1 support to the
+  library itself — pushed to Phase 8.10.
+- Long-form stress: 1800-frame VP9 1080p (60s @ 30fps),
+  120.9 fps sustained, p99 17.3 ms/frame, no errors, no
+  leaks, daemon alive after 3620 cookies across two runs.
+- HDR multi-codec byte-exact: VP9-10bit (48.8 fps,
+  from 8.8), AV1-10bit (17.1 fps), H.264-10bit (26.9 fps).
+  10-bit is intrinsically more expensive — AV1 falls
+  short of 30fps but acceptable for the user-facing
+  goal (mostly SDR YouTube).
 
-After 8.9 the project's user-facing loop is closed.  Optimisation
-phases (QPU dispatch, 4K, encoders) ship when motivated.
+See `docs/phase_8_9_closure.md`.
+
+### Phase 8.10 — libva-v4l2-request VP9/AV1 patch + end-to-end consumer
+
+1. Build libva-v4l2-request from source on hertz.
+2. Add VP9_FRAME + AV1_FRAME profile mappings; add
+   V4L2_PIX_FMT_NV12 (single-plane) to our CAPTURE so
+   the library's video.c picks us.
+3. End-to-end: `mpv --hwdec=vaapi` against test files;
+   then Firefox.
+4. (Stretch) Upstream the patches to bootlin.
+
+After 8.10 the project's user-facing loop is closed.
+Optimisation phases (QPU dispatch, 4K) ship when motivated.
 
 ## Effort estimate