Vance Ingalls 4279ba20e5 feat(producer): add shaderTransitionWorkerPool ...

hf#677 follow-up. Adds a `worker_threads`-based pool that runs the
shader-transition blend (one of 15 transition shaders) on a fixed-size
worker pool. No production wiring yet — the pool stands alone and the
hybrid path in PR 4 wires it up.

Why a separate pool: the shader blend is a hot inner loop iterated
over every pixel of every transition frame at 16bpc. Running it on the
main event loop was previously the dominant wall-time bottleneck once
DOM capture parallelism was reached. Moving it to `worker_threads`
unblocks the main thread for CDP dispatch and pipelined decode/blit.

Pieces:

* `shaderTransitionWorker.ts` — the worker entry. Imports `TRANSITIONS`
  + `crossfade` from `@hyperframes/engine/shader-transitions` (the
  subpath added here on the engine package). Like the alpha-blit
  subpath, this is a zero-import TS file so it survives the
  `new Worker(<path>)` loader boundary without dragging in the producer
  module graph.

* `shaderTransitionWorkerPool.ts` — fixed-size pool with `run()` API.
  Uses `transferList` so the 16bpc HDR `from`/`to`/`out` buffers move
  by ownership across the boundary instead of being copied.

* `shaderTransitionWorkerPool.test.ts` — 6 vitest tests pinning byte-
  equivalence across all 15 shaders against an inline reference,
  transferList correctness, and pool lifecycle (concurrent dispatch +
  termination). All pass.

Build wiring:

* `packages/cli/tsup.config.ts`: third tsup entry emits
  `dist/shaderTransitionWorker.js` alongside `dist/cli.js`. Same
  rationale as the pngDecodeBlitWorker entry in PR 2 — the pool's
  `new Worker(<path>)` resolver probes for that file next to its
  loaded module.

* `packages/producer/build.mjs`: fourth esbuild entry emits the worker
  as `dist/services/shaderTransitionWorker.js` for direct producer
  consumers. Adds the `@hyperframes/engine/shader-transitions`
  workspace alias to the existing `workspaceAliasPlugin`.

* `packages/engine/package.json`: adds `./shader-transitions` subpath
  export pointing at `src/utils/shaderTransitions.ts`. The file is
  already import-free so the worker can consume the TS source directly.

No behavior change in any render. PR 3 of 5 in the hf#732 decomposition
stack; stacked on top of PR 2 (pngDecodeBlit pool).

-- Vai

Co-Authored-By: Vai <vai@heygen.com>

2026-05-13 20:24:27 +00:00

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