Pressing "New chat" while a brand-new chat's first turn was still streaming
only removed the role badge — the thread, session and stream were kept. The
thread remount is driven by a render-phase reconciler in useChatSession that
fires only when activeChatId !== thread.chatId; on a not-yet-adopted new chat
both are null, so startNewChat's setActiveChatId(null) was a no-op and nothing
remounted.
- useChatSession: add startFreshThread(), which unconditionally dispatches a
reconcile to a fresh mount key so ChatThread remounts even when activeChatId
stays null. startNewChat now calls it.
- Guard against the abandoned thread's late finish: ai@6's useChat does not
abort on unmount and proxies its callbacks, so onFinish/onError of the chat
the user just left still fire and would adopt it back. onTurnFinished now
takes the finishing thread's key and, when it no longer matches the mounted
thread, only refreshes the chat list — no adoption, no fallback arming, no
per-chat message invalidation. ChatThread forwards its threadKey in both
onFinish and onError. An omitted key (legacy callers/tests) counts as the
current thread, preserving the #137 adoption behavior.
Tests: 3 new useChatSession cases (fresh-thread remount with activeChatId null,
abandoned-thread finish rejected, current-thread finish still adopts). Full
ai-chat suite green (183).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Closes the 4th PR #138 review (3 suggestions, no blockers).
- Double-call safety: a failed turn fires both useChat onFinish AND onError, so
onTurnFinished can run twice in one turn (streamed id, then no id) before a
re-render. onTurnFinished now reads the live id from a ref (set imperatively on
primary adoption) instead of the stale closure, so the 2nd no-id call cannot
re-arm the error-path fallback at the source; the render-phase reconciler is the
second layer. Added a hook test for the sequence — verified it fails only if
BOTH layers are removed (non-tautological).
- Conventions: extracted named UseChatSessionOptions / UseChatSessionResult
interfaces (was an inline param literal + ChatSession); the test derives its
driver props from them.
- Simplification: extracted the chatIdSnapshot(chats) projection used at both the
fallback arm site and the resolver effect.
Architecture notes from the review (caller-driven disarm contract; cross-process
{chatId} type) intentionally left as Variant A per the reviewer's recommendation.
tsc clean; 128 ai-chat tests green.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Closes the 3rd PR #138 review.
Warning fix: the render-phase reconciler only disarms the error-path adoption
fallback when activeChatId actually changes. Pressing 'New chat' while ALREADY
in a new chat keeps activeChatId === null (a no-op atom write), so the reconciler
never fired and a stale armed fallback could adopt the just-failed chat from a
late refetch, yanking the user out of their fresh chat. useChatSession now
returns cancelPendingAdoption(); the window calls it from startNewChat AND
selectChat. (The hook call moved above those callbacks so they can reference it.)
Added a hook test that fails without the explicit disarm, plus a test for the
existing-chat onTurnFinished branch (no adoption + per-chat invalidation).
Cleanups: removed the dead pickNewlyCreatedChatId (the fallback effect uses
newlyAddedChatIds directly with the 0/1/>1 decision inline) and its tests/doc
mention; inlined the two invalidation closures (onTurnFinished is read live by
useChat's onFinish, never in an effect dep array, so memoizing them was needless
ceremony).
Verified: tsc clean, 127 ai-chat tests green; live (z.ai glm-5.2) new chat + 2nd
turn recalled the number in the SAME row (1 chat / 4 messages), no page errors.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Addresses the 2nd PR #138 review (test debt + the Variant-B architecture ask).
The new→persisted chat id lifecycle (mount key, both adoption paths, the
history-load latch, the render-phase reconciler, onTurnFinished) is moved out of
the 768-line window into a new useChatSession hook driven by a pure
threadSessionReducer (reconcile/adopt), so adopt-vs-switch is one explicit
dispatch point and the scattering the review flagged is gone (window: 768→~620).
Tests (the blockers):
- use-chat-session.test.tsx — hook-level locks incl. the #137 regression
(adopts the authoritative streamed id 'A', NOT chats.items[0]='B' — fails on
the old heuristic), the error-path fallback (arm/adopt/ambiguous/add+delete),
the disarm-on-reconcile lock (a fallback armed then switched away must not be
adopted by a late refetch), in-place-adopt-keeps-key vs external-switch-remount,
and the waitingForHistory latch.
- extractServerChatId (reading message.metadata.chatId) and newlyAddedChatIds
extracted as pure helpers with unit tests; threadSessionReducer tested.
Cleanups: single canonical #137 explanation in adopt-chat-id.ts (other sites
reference it); fallback effect computes the set diff once; invalidate callbacks
memoized; redundant invariant tests folded.
Behavior preserved — re-verified live (z.ai glm-5.2): new-chat adopt + 2nd turn
in the same row, no mid-conversation remount, two-tab race leak-free, switch to
an existing chat reseeds full history, reload restores history.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
