fix(langgraph): restore conversation on reconnect to existing thread#219
Merged
Conversation
Targets Finding D from the live smoke pass: after a page reload, the
conversation is NOT restored even though the threadId is persisted in
localStorage and passed to agent({threadId}).
Root cause: refreshHistory() populates history$ but does not project
the latest checkpoint into messages$ or values$. The chat composition
reads messages$, so the user sees the welcome state.
Fix: extend refreshHistory to project history[0].values into messages$
and values$ on first connect. Guarded by a "messages$ is empty" check
so an optimistic local submit that beats history fetch is preserved.
12 LOC change in the bridge plus 2 unit tests pinning the restore
path and the race-guard.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Five-phase plan: branch, TDD failing restore test, implementation (extend refreshHistory to project latest checkpoint into messages$ + values$, guarded by messages$ empty check), race-guard test, verification + PR. ~92 LOC, 2-3 commits. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Targets Finding D from the live smoke pass: after a page reload, the conversation is NOT restored even though the threadId is persisted in localStorage and passed to
agent({ threadId }).Root cause
refreshHistory()populatessubjects.history$from the transport's checkpoint history but does not project the latest checkpoint'svalues.messagesintosubjects.messages$. The chat composition readsmessages$(nothistory$), so the user sees the welcome state instead of their prior conversation.Fix
After the existing
subjects.history$.next(history)line, project the most recent checkpoint intomessages$andvalues$. Guarded bymessages$.value.length === 0so an optimistic local submit that beats the history fetch is preserved.The
messagesfield is stripped fromvalues$so consumers reading both subjects don't see duplicates —messages$is the canonical surface.Test plan
Verified locally
nx run langgraph:lint— 0 errorsnx run langgraph:test— 55 tests pass (53 existing + 2 new)messages$andvalues$from latest checkpoint on initial connectPending visual verification
examples/chatdemo. Send a message → reload → conversation reappears with prior user/assistant exchange visible. No flash of welcome state.Spec:
docs/superpowers/specs/2026-05-08-langgraph-thread-restoration-design.mdPlan:
docs/superpowers/plans/2026-05-08-langgraph-thread-restoration.md