stacklok / toolhive-studio / 25811957726 / 1

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Pull #2246

github

fix(playground): prevent queue auto-flush into wrong thread on switch

Cross-thread leak from #2246 review: when the user queued a message in
thread A and switched to thread B before A's stream finished, the
auto-flush effect could fire A's queued payload into B's `useChat`
instance. The thread-clear `useEffect` ran on the same render as the
auto-flush — both see the stale `queuedMessage`, and the prev-status
ref still held A's `'streaming'` so the streaming→ready transition
falsely matched.

Replace the thread-clear effect with the React-recommended in-render
adjustment pattern (https://react.dev/learn/you-might-not-need-an-
effect#adjusting-some-state-when-a-prop-changes). The queue is reset
synchronously during the render where `currentThreadId` changes, so
the auto-flush effect that runs after commit sees `null` and skips.
Also reset the prev-status ref in the same block so the transition
detector doesn't false-trigger on the cross-thread status reset.

Regression test mounts in thread A streaming + queued, switches to B
with status='ready', and asserts `sendMessage` is never called.

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