# iter4 Phase 7 status — paused (fresnel offline)

## Where we paused

After surfacing **3 distinct bug classes** in Phase 7 verification (criterion 4 + 5 fail), user picked **Option A** (VP9-only fix, criterion 4 transitive).

Mid-fix, found that Bug 1 (Clause 6 parser bit-misalignment) had a deeper root cause:

- `src/context.c:194` set `context_object->h264_start_code = true` unconditionally
- `src/picture.c:70` therefore prepended `0x00 0x00 0x01` ANNEX-B start code to ALL slice data, including VP9
- VP9 has no start codes → kernel rkvdec read garbage uncompressed_header → silent decode failure → CAPTURE buffer stayed at cap_pool init pattern (0x4c green)

**Fix landed** in fork commit `692eaa0`: switch on `config_object->profile`; set `h264_start_code = true` only for VAProfileH264* and VAProfileHEVCMain.

**Empirical verification when fresnel was online**: post-fix VP9 keyframe FRAME control bytes 0-23 byte-match Phase 3 anchor exactly.
- pre-fix: lf.flags=0x01, base_q_idx=0x41 (bit-misaligned)
- post-fix: lf.flags=0x03 (DELTA_ENABLED|DELTA_UPDATE), base_q_idx=0x2e=46 (matches anchor)

**Open verification when fresnel returns**:
1. Diff full FRAME control payload (all 168 bytes) mine vs Phase 3 anchor — confirm full byte-match (transitive proof leg 1).
2. Diff full COMPRESSED_HDR control payload (2040 bytes) mine vs Phase 3 anchor — same.
3. ffmpeg-v4l2request VP9 decode + hwdownload (kernel-direct path, NOT via libva): confirm pixels match Phase 3 SW reference (transitive proof leg 2).
4. Both legs satisfied → criterion 4 transitive PASS.

If transitive proof PASSES, iter4 closes with:
- Criterion 1: PASS (vainfo)
- Criterion 2: PASS (implicit)
- Criterion 3: PASS (ffmpeg-vaapi exit 0)
- Criterion 4: PASS-transitive (per iter3 precedent + memory `reference_dmabuf_resv_blocker.md`)
- Criterion 5: still partial — Bug 2/3 are substrate-wide, NOT iter4 scope.

Campaign scoreboard moves to 5/5 (4 direct from earlier iters + 1 transitive iter4).

## Memory update

Saved memory `feedback_unconditional_codec_state.md`: future codec-class-specific state MUST be gated on `config_object->profile`, not set unconditionally. iter1/iter3 had this latent bug too.

## Substrate state at pause

- Fork tip `692eaa0` (Phase 7 fix-forward) — on noether + fresnel.
- Backend `.so` installed on fresnel.
- Phase 3 anchor + Phase 7 fixed-strace files persisted on fresnel `/tmp/iter4_phase{3,7}/`.
- Memory rules carry forward.
- iter4 commits chain: Z (`7f8fa93`) -> A (`16b3973`) -> B (`406d08e`) -> C (`beaa914`) -> Phase-7 fix (`692eaa0`).

## Resume cue

When fresnel surfaces, continue from: byte-by-byte diff of FRAME + COMPRESSED_HDR controls vs Phase 3 anchor + ffmpeg-v4l2request VP9 hwdownload pixel comparison.