Picker still stuttered during load because the main thread was stuck
parsing 20+ inbound IPC messages, each carrying 15-25 KB of JSON-wrapped
base64. Two changes compound to fix this:
1. Binary IPC. New Rust command capture_screen_source_thumbnail_bytes
returns `tauri::ipc::Response` with the raw JPEG bytes — no JSON
envelope, no base64 on either side. The frontend wraps the arriving
ArrayBuffer in a Blob and exposes it via URL.createObjectURL so the
browser decodes directly from bytes without a data-URL parse.
Empirically drops per-arrival main-thread work from ~10-15 ms to
~1-2 ms.
2. rAF-batched thumbnail state updates. Arriving blob URLs are staged in
a pendingUrls map and flushed in a single setState on the next
animation frame — multiple arrivals in one frame coalesce into one
render instead of queueing consecutive long tasks. Kept startTransition
on top so the commit stays on the low-priority lane.
Thumbnails are also dropped to 192×108 / Q60 (from 240×135 / Q70) for
~2× smaller payloads. Blob URLs get revoked on picker close so native
buffers don't leak across opens.
SourceCard now takes `thumbnailUrl` as a separate prop from a parent-
held map. Keeps source object references stable so React.memo's
identity check only fires a card re-render when THAT card's URL
actually lands, instead of every card whenever any URL changes.
Next session: WASAPI loopback for system-audio capture in native share.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
byGalax
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