Extends RenderConfig.format with "png-sequence" and patches two correctness
gaps so the existing "webm" / "mov" values actually preserve the alpha
channel end-to-end.
Engine fixes:
- screenshotService.pageScreenshotCapture: drop optimizeForSpeed for PNG
captures. The fast path uses an alpha-unaware codec that crushes real
alpha values; kept for opaque jpeg captures where it is harmless.
- frameCapture: replace the inline setDefaultBackgroundColorOverride
block (which fired pre-navigation and was reset by page.goto) with a
proper initTransparentBackground() call inside initializeSession,
after the window.__hf readiness poll. This also injects the
html/body/[data-composition-id]{background:transparent !important}
stylesheet so compositions with custom body / #root backgrounds do not
defeat the override. Wired into both screenshot-mode and beginframe-mode
branches.
Producer:
- RenderConfig.format extended to "mp4" | "webm" | "mov" | "png-sequence"
with full JSDoc.
- Streaming encode is bypassed for png-sequence (frames go straight to
disk). FORMAT_EXT extended.
- New Stage-5 png-sequence branch: mkdir outputPath, copy captured PNGs as
frame_NNNNNN.png, copy audio.aac sidecar when audio is present.
- Stage-6 mux/faststart and the debug copy are wrapped in !isPngSequence.
- README.md: new "Transparent Video Output" section.
Tests:
- New fixture tests/transparency-regression/ tagged "transparency".
- New tsx script src/transparency-test.ts asserts pixel-level alpha for
webm + png-sequence outputs. Wired as "test:transparency".
- Default "test" / "test:update" scripts pass --exclude-tags transparency
so the golden-MP4 harness ignores the new fixture.
Verified locally on macOS arm64: typecheck clean across engine + producer,
producer renderOrchestrator vitest 10/10, transparency-test passes for
both webm and png-sequence with end-to-end pixel assertions.
## Summary
Make the existing benchmark harness genuinely useful for HDR perf work: positive `--tags` filter, peak heap/RSS sampling, a `bench:hdr` script, and a perf README documenting the captured April-2026 baseline. Lands first in the Chunk 8 sub-stack so subsequent perf PRs can be measured against a known starting point.
## Why
`Chunk 8A` of `plans/hdr-followups.md`. Wall-clock timing alone can't catch slow memory regressions like an unbounded image cache — peak RSS does. And the existing harness only had `--exclude-tags`, so HDR runs had to wait for unrelated SDR fixtures.
## What changed
**1. Positive `--tags` filter** in `benchmark.ts`. Adds `--tags hdr` so HDR runs don't have to wait for unrelated fixtures. Filters compose: a fixture must match `--tags` (if provided) AND must not match `--exclude-tags`.
**2. Peak heap + RSS tracking** in `executeRenderJob`. A 250 ms periodic `process.memoryUsage()` sampler runs alongside every render and reports `peakRssMb` / `peakHeapUsedMb` in `RenderPerfSummary`. Sampler is `unref`'d and always cleared in `finally` so it never keeps the event loop alive or leaks across jobs. Both fields are optional on the interface for back-compat with serialized older summaries.
**3. `bench:hdr` convenience script** plus a perf README at `tests/perf/README.md` documenting the harness, the new flags, and the captured April-2026 HDR baseline (PQ regression: 34.5 s / 272 MiB RSS, HLG regression: 11.5 s / 227 MiB RSS, both 1080p / 1 worker / 1 run).
The benchmark output table is widened and gains `PeakRSS` / `PeakHeap` columns. A new `avgOrNull` helper preserves `null` in the JSON when no run reported memory (avoids silently coercing missing data to 0 in older snapshots).
No behavior change for non-benchmark renders — the sampler runs in every `executeRenderJob` but its overhead is a single `process.memoryUsage()` call every 250 ms, well below noise.
## Test plan
- [x] `bunx tsc --noEmit -p packages/producer` — clean.
- [x] `bunx oxlint` / `bunx oxfmt --check` on changed files — clean.
- [x] `bun test src/services/` — 60/60 pass (frameDirCache, orchestrator, etc.).
- [x] `bunx tsx src/benchmark.ts --tags hdr --runs 1` — both HDR fixtures render successfully, summary table prints `PeakRSS`/`PeakHeap` columns, per-run output shows new memory line.
- [x] `bunx tsx src/benchmark.ts --tags nonexistent` — exits 1 with a helpful message naming the active filters.
## Stack
Chunk 8A of `plans/hdr-followups.md`. First PR in the Chunk 8 perf sub-stack; subsequent PRs (image cache, logger gating) measured against this baseline.
Guard buildHyperframesRuntimeScript() against missing entry.ts so it
returns null instead of crashing with esbuild stderr output. Add
getHyperframeRuntimeScript() that returns the pre-built IIFE as a
baked-in string constant — no esbuild, no file I/O, no import.meta.url.
Consolidate CLI runtime source resolution into a single module with
a clear priority chain: esbuild from source (dev) → inlined constant
(production) → pre-built artifact file (fallback).
Add CI smoke test that npm-packs the CLI, installs globally, runs
hyperframes preview, and asserts no stderr errors + runtime endpoint
returns JS.
Bump version to 0.4.16.
Miguel Ángel