A thread could hold multiple resolved comments at once: ResolveComment
was a plain per-row setter that never cleared the prior resolution, and
"replacing" one was a display-only illusion (deriveThreadResolution
picks the max resolved_at). The stale rows stayed resolved in the DB and
the optimistic update flashed the new resolution, then reverted.
Make single-resolution-per-thread a write invariant:
- ClearOtherThreadResolutions: thread-scoped clear via a RECURSIVE CTE
(root + descendants of the target, id <> target), returns each cleared
row.
- ResolveComment handler runs the clear + set in one tx so the replace
is atomic. It emits comment:unresolved per cleared sibling (granular
realtime consumers patch a single comment in place and would otherwise
keep showing the stale resolution). Target keeps its COALESCE
idempotency and the re-resolve event suppression.
- Frontend optimistic update mirrors the invariant: resolving clears
every other resolution in the same thread, so the cache never shows
two at once. Unresolve still only clears its own row.
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: multica-agent <github@multica.ai>
