SPEC-002 Phase 1 Task 7 (the last), code-reviewed APPROVED, locally verified
(cargo fmt + clippy -D warnings exit 0 + cargo test --workspace 89 pass + build).
- Encoder trait + factory: RawEncoder (salvaged, UNCHANGED) and H264Encoder,
selected by negotiation; factory falls back to raw on H.264 init failure.
- Negotiation: agent advertises supports_h264 (MFTEnumEx HW probe, cached) in
AgentStatus; server picks the codec via select_video_codec(supports, prefer)
and stamps StartStream.video_codec; agent re-guards on local HW. Policy
constant DEFAULT_PREFER_H264 = false, so RAW is negotiated for every session
today - H.264 stays dormant until live hardware validation (Task 8).
- MF H.264 encoder (h264.rs, FIRST-CUT / compile-verified-only): HW encoder MFT,
BGRA->NV12 (color.rs, unit-tested), sync drain, fall-back-to-raw on any failure.
- Viewer H.264 decoder (decoder.rs, FIRST-CUT): MF decoder on a dedicated COM
thread; drops+logs on failure, raw render path untouched.
- proto additive: VideoCodec enum, StartStream.video_codec=3,
SessionResponse.video_codec=5, AgentStatus.supports_h264=11.
- Raw+Zstd path byte-for-byte unchanged; remains the guaranteed default/fallback.
Review confirmed unsafe impl Send for H264Encoder is sound (single-owned &mut on
the block_on thread; session future never spawned) and every MF failure degrades
to raw. H.264 is NOT claimed functional - compile/clippy/build-verified only;
live validation + force-IDR + the no-spawn-invariant doc are Task 8 go-live gates.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
