test(engine): cover spawnStreamingEncoder lifecycle and cleanup paths

[vanceingalls]

Summary

Add unit tests that mock child_process.spawn to drive an in-memory "ffmpeg" through the success/failure paths used by the producer's HDR encoder and by Chunk 5A's defensive close() in renderOrchestrator.

Why

Chunk 9D of plans/hdr-followups.md. The contracts the orchestrator's try/finally cleanup (Chunk 5A) and the abort path rely on were entirely uncovered. A regression in spawnStreamingEncoder's lifecycle handling would surface as a leaked ffmpeg process or a hung render, both of which are hard to diagnose after the fact.

What changed

packages/engine/src/services/streamingEncoder.test.ts: 7 new specs covering:

• Successful exit after explicit close().
• Non-zero exit before close() returns a failure result (no throw).
• ENOENT on spawn returns a failure result (no throw).
• Abort signal triggers SIGTERM and a "cancelled" result.
• close() is idempotent and never throws on a second call.
• writeFrame returns false after the encoder has exited.
• close() detaches the abort listener so post-close aborts don't re-kill ffmpeg.

These contracts are what the renderOrchestrator try/finally cleanup added in Chunk 5A relies on, and what the ffprobe-unavailable test (Chunk 9B) hinted at for the encoder side.

Test plan

• All new specs pass.
• No production code changes — pure regression coverage of existing lifecycle behavior.

Stack

Chunk 9D of plans/hdr-followups.md. Test-only change, complements Chunk 5A.

[vanceingalls]

• docs(engine): document __name polyfill and add regression test #385
• perf(producer): cache transfer-converted hdr image buffers per render job #384
• perf(producer): gate per-frame debug meta via optional isLevelEnabled #383
• perf(producer): hdr benchmark harness — --tags filter, peak heap/RSS tracking, bench:hdr script #382
• test(producer): extract frameDirMaxIndexCache to its own module and pin cross-job isolation #381
• test(engine): cover spawnStreamingEncoder lifecycle and cleanup paths #380 👈 (View in Graphite)
• test(engine): add ffprobe-unavailable fallback regression tests #379
• test(shader-transitions): add midpoint (p=0.5) regression invariants for all shaders #378
• test(engine): lock down sRGB→BT.2020 LUT with byte-exact reference values #377
• build(lfs): track tests/*/src/*.png via Git LFS #376
• test(hdr-regression): tighten Window F maxFrameFailures budget after Chunk 4 fix #375
• fix(engine,shader): handle matrix3d transforms and hide non-first scenes #374
• refactor(producer): extract HDR compositing helpers and rename media metadata #373
• fix(producer): wire --crf and --video-bitrate CLI overrides into encoders #372
• fix(producer): tighten resource lifecycle and harden file server #371
• feat(engine): wire options.hdr through chunkEncoder + dynamic SDR→HDR transfer #370
• test(hdr-regression): tighten Window C maxFrameFailures budget after Chunk 1 fix #369
• fix(engine): stop clobbering native <video> opacity in HDR pipeline #368
• refactor(shader-transitions): extract DEFAULT_DURATION and DEFAULT_EASE constants #367
• refactor(types): tighten type safety, dedupe HfTransitionMeta, prune dead LUT export #366
• test(producer): add hdr-regression and hdr-hlg-regression test suites #365
• main

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[vanceingalls]

Merge activity

• Apr 23, 8:10 PM UTC: @vanceingalls merged this pull request with Graphite.