Issue: HIGH priority item from canvas accessibility audit (2026-05-09).
Screen reader users had no way to know when workspace status changed
— the canvas updated visually but no announcement was made.
Changes:
- canvas.ts: add `liveAnnouncement: string` + `setLiveAnnouncement` to
CanvasState so the store can hold the current announcement text.
- canvas-events.ts: set `liveAnnouncement` in handleCanvasEvent for 6
key status transitions: ONLINE, OFFLINE, PAUSED, DEGRADED, PROVISIONING,
REMOVED, PROVISION_FAILED. Names are looked up from store nodes so
announcements are human-readable ("Alpha is now online" not "ws-1").
TASK_UPDATED and AGENT_MESSAGE are intentionally excluded — they fire
on every heartbeat and would overwhelm the user.
- Canvas.tsx: subscribe to `liveAnnouncement` from the store; render a
visually-hidden `aria-live="polite" aria-atomic="true"` region that
speaks the announcement then clears it after 500 ms so the same
message doesn't re-announce on re-render. Fallback still announces
workspace count on initial load.
- canvas-events.test.ts: 12 new test cases covering announcement
content for all 6 event types, empty/no-announcement cases, and
payload-name fallback when a node isn't yet in the store.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
