Recording: webm works (native MediaRecorder), gif captures but doesn't download

[petercorke]

Background

Found and partly fixed 2026-07-26 producing example recordings for the
README. recording.js's Recorder class used CCapture
(js/vendor/build/CCapture.all.min.js) for every format. Two separate
bugs found:

1. webm was completely broken -- CCapture's webm encoder mux-es
   per-frame WebP images (canvas.toDataURL("image/webp")), which
   Safari has never supported from a canvas -- fails silently there,
   producing a 243-byte (effectively empty) file every time regardless
   of recording length. Fixed: webm now uses the browser's native
   MediaRecorder API (canvas.captureStream() +
   new MediaRecorder(stream, {mimeType: "video/webm"})) instead of
   CCapture -- no WebP involved, confirmed producing real multi-MB
   files. gif/png/jpg are unaffected by this specific bug and still use
   CCapture.
2. Swift.stop_recording() never reset self.recording = False --
   a second start_recording() call in the same session always raised
   "You are already recording", even though the first recording had
   genuinely already stopped. Fixed.
3. Separately: gif.worker.js (needed by CCapture's gif/webm encoders,
   loaded at runtime as a Worker script) was never vendored -- only
   shipped under ccapture.js's src/, not build/. Fixed (vendor
   script + rerun).

Still broken, not yet fixed: after fix #3, GIF encoding genuinely
runs (confirmed via CCapture's own status overlay showing real frame
counts, e.g. "CCapture gif | 640 frames | 00:00:32"), but .save()
never triggers an actual browser download -- no file ever appears, and
there's no visible save/download control in that overlay to click
either. Not root-caused: could be an async encoding step that never
completes, or a broken/no-op internal call to whatever download helper
CCapture normally uses.

Proposed fix

Either root-cause CCapture's gif save path specifically (would need to
step through the minified bundle or find an unminified source), or
replace it the same way webm was replaced -- record a MediaRecorder
webm and convert to gif via an external tool/service, or find a modern
maintained gif-encoding library to vendor instead of ccapture.js
(unmaintained, last released ~2017, predates MediaRecorder being
universal). The latter is probably the more durable fix long-term,
consistent with the "modern, no framework, current dependencies"
direction the rest of the 2026 rebuild took.