refactor(shader-transitions): extract DEFAULT_DURATION and DEFAULT_EASE constants

[vanceingalls]

Summary

Extract DEFAULT_DURATION = 0.7 and DEFAULT_EASE = "power2.inOut" as shared constants in hyper-shader.ts and apply them at all three fallback sites (metadata write, browser/render mode, engine mode).

Why

Chunk 2 of plans/hdr-followups.md. The three fallback sites had drifted apart: the metadata path used 1s / "none" while the actual rendering used 0.7s / "power2.inOut". A transition that omitted duration/ease would render at 0.7 s but tell the producer it was 1 s, throwing off the producer's compositing window planning and producing a visible ~0.3 s brightness dropout.

This is a small, high-value correctness fix that runs before the larger Chunk 1 / Chunk 4 work.

What changed

• New module-level DEFAULT_DURATION and DEFAULT_EASE constants in packages/shader-transitions/src/hyper-shader.ts.
• All three fallback call sites (metadata, browser, engine) now use the constants.
• Explicit ease: "none" on the timeline-length anchor tweens elsewhere in the file is intentional (those are linear interpolators driving the shader's progress uniform) and is left unchanged.

Test plan

• Render a composition with a transition that omits duration and ease — no brightness dip in the last ~0.3 s of the transition.
• Preview (browser mode) and render (engine mode) produce matching blending curves.
• Render with explicit duration: 1.5 still works (constants are fallbacks only).

Stack

Chunk 2 of plans/hdr-followups.md. Lands ahead of Chunk 1 (opacity) per the suggested merge order.

[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
• 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 👈 (View in Graphite)
• 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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[jrusso1020]

Nice cleanup that surfaces a real bug. Before this PR the meta-write path used duration ?? 1 + ease ?? "none" while the render-mode and engine-mode paths used duration ?? 0.7 + ease ?? "power2.inOut". Concretely: a transition declared without explicit duration would play for 0.7s with power2.inOut but be reported in the __hf.transitions metadata as 1s with "none" — so the producer's HDR compositor would plan a 1.0s compositing window while the actual shader animation only ran 0.7s. The difference gets papered over in most compositions (transitions usually declare both fields) but any default-relying transition would have misaligned encoder buffers against the visual output.

Extracting DEFAULT_DURATION / DEFAULT_EASE to module-scope constants and using them at all three sites both fixes the inconsistency and prevents it from drifting back. Approved.

— Rames Jusso

[vanceingalls]

Confirmed — the analysis is right. The pre-PR mismatch (1.0s + "none" in the meta path vs. 0.7s + "power2.inOut" in the shader path) was exactly the kind of latent encoder/visual desync that only surfaces when a composition omits both duration and ease, which is rare enough in production that it never tripped a regression test. Centralizing on DEFAULT_DURATION / DEFAULT_EASE collapses all three sites onto a single source of truth so a future tweak to defaults can't reopen the gap. No follow-ups required.

[graphite-app]

Merge activity

• Apr 22, 11:58 PM UTC: Graphite rebased this pull request, because this pull request is set to merge when ready.
• Apr 23, 12:02 AM UTC: @vanceingalls merged this pull request with Graphite.