* fix(render): make WebGL video textures deterministic in headless render
WebGL compositions that sample a `<video>` as a texture (e.g. a faceted
crystal with clips mapped onto its facets) rendered with flickering,
non-deterministic facets: a video would intermittently show a stale frame or
go black, and the same frame differed between two renders.
Two gaps caused this:
1. No WebGL analog of the WebGPU `patchVideoTextureCompat`. Chrome's headless
compositor can't feed decoded `<video>` frames to the GPU, so the engine
injects a decoded `<img class="__render_frame__">` sibling per video each
frame. The WebGPU `copyExternalImageToTexture` path substitutes it, but
`texImage2D` / `texSubImage2D` did not — so WebGL uploaded a stale/black
frame. Add `patchWebGLVideoTextureCompat()` mirroring the WebGPU patch
(shared `resolveRenderFrameImage` helper).
2. Capture ordering. Per frame the runtime seeks (GPU adapters render on
`hf-seek`) BEFORE the engine injects the decoded frames, so the GPU render
read a frame that didn't exist yet. After injecting, the engine now calls
`window.__hfReseekGpu(t)` — a force-dispatch (`forceDispatchSeekEvent`) that
bypasses the same-time `hf-seek` dedup — so GPU compositions re-upload their
textures from the freshly-injected, decoded frames, deterministically.
Tests: unit tests for the texImage2D/texSubImage2D substitution and the
force-dispatch, plus a videoFrameInjector regression test asserting the
post-injection GPU reseek fires only when frames were injected. Verified
end-to-end: a WebGL prism with 8 live <video> facets renders byte-identical
across independent runs with no facet flicker.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* test(render): add producer render-compat regression for WebGL video textures
A WebGL2 canvas samples a <video> as a texture every hf-seek (the natural
author pattern, distilled from the HeyGen prism). The render-compat harness
renders it and compares against the golden: with the video-texture fix the
render reproduces the decoded frames; revert the fix and the canvas renders
black, collapsing the comparison.
Golden verified to contain real, time-varying video content (not black), so a
regression is caught rather than passing vacuously.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
