Expand description
Cocoon → Mountain progress.report notification.
The git extension alone fires 6000+ of these per session. We push into
an mpsc::unbounded_channel; a single long-lived flusher task wakes on
the first item, drains everything queued, sleeps 16 ms (one frame), drains
again, then emits one batched Tauri event per progress handle with the
accumulated increment and latest non-empty message. Zero spawns per
call; sub-millisecond first-wake; single event per handle per frame.