## Summary
Tighten `hdr-regression` Window F `maxFrameFailures` from 5 → 0 now that Chunk 4 (matrix3d support + scene initial-state) has landed.
## Why
Window F (transform + scale + border-radius on the video itself) was the remaining known-fail in the `hdr-regression` suite, baked into the golden so the suite stayed green while Chunk 4 was outstanding.
After Chunk 4 fixed `parseTransformMatrix` (matrix3d support) and the shader-transitions initial-state, re-running the suite shows **0 failed frames** against the existing golden — the encoder is byte-deterministic, and Window F's GSAP rotation/scale happens to emit 2D `matrix()` rather than `matrix3d()`, so the same golden is still correct after the fix. Tightening the budget catches any drift in the layered HDR compositor immediately.
## What changed
- `tests/hdr-regression/meta.json`: `maxFrameFailures` 5 → 0 (matches `hdr-hlg-regression`).
- `tests/hdr-regression/README.md`: Window F row + Fix history section updated to reflect the new state.
## Test plan
- [x] `bun run test --filter hdr-regression` — passes with 0 failed frames at the new budget.
## Stack
Follow-up to Chunk 4 (transform & clipping). Reviewable separately so the budget tightening is decoupled from the code fix.
## Summary
Four behavior-preserving refactors that reduce complexity in `renderOrchestrator.ts` and clarify the engine ffprobe utility surface. Lands after the correctness fixes (Chunks 1–5) so the refactored code is already correct.
## Why
`Chunk 7` of `plans/hdr-followups.md`. The HDR composite block had grown a ~200 LOC inline closure with 14 captured deps, a repeated capture-options spread, a `extractVideoMetadata` name that now also handles still images, and per-frame re-creation of debug helpers.
## What changed
**7A — Hoist `compositeToBuffer` into a module-scoped helper.** Extract the inline HDR closure into a top-level `compositeHdrFrame()` that takes an `HdrCompositeContext` struct. Construct the context once at the top of the HDR render block and pass it through. Removes a deeply-nested closure from the middle of the orchestrator.
**7B — `buildHdrCaptureOptions()` helper.** Factor the repeated `{ ...captureOptions, skipReadinessVideoIds: ... }` spread into a named helper at the call site.
**7C — Rename `extractVideoMetadata` → `extractMediaMetadata`.** Reflects that the helper handles still images (PNG/JPEG/WebP) in addition to video. Update all callers in engine + producer (`videoFrameExtractor`, `htmlCompiler`, regression-harness, producer ffprobe re-export, tests). Re-export the old name as a deprecated alias from `@hyperframes/engine` for backward compatibility, plus the producer re-export shim.
**7D — Hoist debug counters to module scope.** `countNonZeroAlpha` and `countNonZeroRgb48` are now module-scoped so they aren't re-created per frame and so the closure has fewer captures.
Also touches the `hdr-regression` and `hdr-hlg-regression` README + `meta.json` files reviewed during this refactor.
## Test plan
- [x] `bunx tsc --noEmit -p packages/producer && bunx tsc --noEmit -p packages/engine` clean.
- [x] Engine tests: 313 pass, 0 fail (1218 expect calls).
- [x] `bunx oxlint` + `bunx oxfmt --check` clean on 8 changed source files.
- [x] Diff is structural only — no behavioral changes.
## Stack
Chunk 7 of `plans/hdr-followups.md`. Lands after the correctness fixes (Chunks 1–5) per the suggested merge order.
## Summary
Replace the trivial `hdr-pq` and `hdr-image-only` tests with two consolidated, time-windowed regression suites that exercise the full HDR pipeline. These goldens are the safety net for every other PR in this stack.
## Why
The pre-existing HDR tests covered only a single full-bleed video or image with a static text label — none of the features that the HDR pipeline has to handle differently from SDR (opacity animation, z-ordered multi-layer compositing, transforms, border-radius clipping, shader transitions, multiple HDR sources, object-fit modes, mixed HDR+SDR layering, HLG transfer). This PR builds the missing safety net first so every subsequent fix can be proven correct.
## What changed
- New `packages/producer/tests/hdr-regression/` (PQ, BT.2020, ~20 s, 1080p, 8 windows A–H):
- A: static baseline (HDR video + DOM overlay)
- B: wrapper-opacity fade
- C: direct-on-`<video>` opacity tween (documents the Chunk 1 bug)
- D: z-order sandwich (DOM → HDR → DOM)
- E: two HDR videos side-by-side (pins PR #289)
- F: rotation + scale + border-radius (documents the Chunk 4 bug)
- G: `object-fit: contain`
- H: shader crossfade between HDR video and HDR image
- New `packages/producer/tests/hdr-hlg-regression/` (HLG, ARIB STD-B67, ~5 s, 2 windows A–B) — exercises the separate HLG LUT/OETF code path that previously had **zero** coverage.
- New `scripts/generate-hdr-photo-pq.py` synthesizes `hdr-photo-pq.png` with a cICP chunk for BT.2020/PQ/full.
- Removed `tests/hdr-pq/` and `tests/hdr-image-only/`.
- Updated `.github/workflows/regression.yml` HDR shard to run the new pair sequentially.
- All compositions follow the documented timed-element pattern (`data-start`, `data-duration`, `class="clip"` directly on each timed leaf — no wrapper inheritance).
## Test plan
- [x] Goldens generated with `bun run test:update --sequential`.
- [x] `ffprobe` confirms HEVC/yuv420p10le/bt2020nc/smpte2084 (PQ) and arib-std-b67 (HLG).
- [x] Suite green with `maxFrameFailures` budgets that absorb the documented Chunk 1 / Chunk 4 known-fails — tightened in follow-up PRs in this stack.
## Stack
Foundational PR for the HDR follow-ups stack (Chunk 0 of `plans/hdr-followups.md`). Every subsequent PR builds on this safety net.
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