Closes#2069. removeSubtree dropped a parent + descendants locally
after DELETE returned 200, but a GET /workspaces request that was
IN-FLIGHT before the DELETE completed could land AFTER and hydrate
the store with a stale snapshot — re-introducing the deleted nodes
on the canvas until the next 10s fallback poll corrected it.
New module canvas/src/store/deleteTombstones.ts holds a transient
process-lifetime Map<id, deletedAt>. removeSubtree calls
markDeleted(removedIds); hydrate calls wasRecentlyDeleted(id) to
filter the incoming workspaces. TTL is 10s — matches the WS-fallback
poll cadence so a single round-trip is covered, after which a
legitimately re-imported id flows through normally.
GC happens lazily at every read AND at write time so the map stays
bounded — no separate timer / interval / unmount plumbing.
Tests:
- canvas/src/store/__tests__/deleteTombstones.test.ts: 7 cases
covering immediate flag, never-marked, TTL boundary (9999ms vs
10001ms), GC-on-read, GC-on-write, re-mark resets timestamp,
iterable input.
- canvas/src/store/__tests__/canvas.test.ts: end-to-end "hydrate
cannot resurrect ids that removeSubtree just dropped (#2069)"
exercises the full chain at the store level.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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