Desktop MP4 export renders frames from a hidden BrowserWindow via
capturePage, pipes PNGs to a bundled ffmpeg (libx264/yuv420p/+faststart),
and writes the file through an atomic temp-file swap. It shares scene
validation (shared/renderValidation.cjs) and the render.html renderer with
the standalone Puppeteer server, which is hardened in parallel.
Render worker & main (electron/):
- abortable render loop with an inactivity watchdog and cancel plumbing
- atomic temp-file + rename so a cancel/failure never truncates a
pre-existing target (#7); stdin EPIPE / early-exit / backpressure-hang
handled (#8)
- HiDPI frames normalized to canvas size (#10); odd dimensions padded to
even (#13, also server); backgroundThrottling disabled (#12)
- reject canvases larger than the display (#11); single-render guard;
isolated render session that blocks network requests (#5)
Tests:
- Electron harnesses (scripts/verify-*.cjs) for capture, export, cancel,
timeout, assets, background, capture-fidelity, resolution, odd-dims,
aggregated by verify-desktop-render.cjs
- server smoke + e2e and shared validation unit tests
- headless hook (src/devtools/headless.ts) to run the in-app suite under
browser/electron hosts; pixel-diff util + capture fixtures (test/)
- dev_docs plans: integration, fixes (#7-#13), and the e2e/capture strategy
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
