fix(chat): bail refreshMessagesUntilTurn poll on session switch - #209
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PR-FE-BUG-HUNT-4 (LOW from kenji-led bug-hunt 2026-06-24 round 1): `refreshMessagesUntilTurn` polls `readMessages` every 40ms for up to 1200ms while waiting for a freshly-sent user turn to land in the session journal. The setState was already gated on `activeIdRef.current === sessionId`, but the IPC call itself kept firing until the deadline — burning bandwidth and CPU on a session the user no longer cared about. Fix: check `activeIdRef.current !== sessionId` at the top of each loop iteration AND immediately after the await. Bail early so the polling cycle stops, not just the setState. Same guard on the deadline-fallthrough `refreshMessages(sessionId)`. Behavior change is invisible when the user stays on the same session (common case). Saves up to 30 IPC roundtrips per session-switch during the post-send window when the user navigates fast. Single function, single file. No conflict with #202 / #204 / #206 / #207 since none of those touch `refreshMessagesUntilTurn`.
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PR-FE-BUG-HUNT-4 (LOW from kenji-led bug-hunt 2026-06-24 round 1).
Bug
`refreshMessagesUntilTurn` polls `readMessages` every 40ms for up to 1200ms while waiting for a freshly-sent user turn to land in the session journal. The setState was already gated on `activeIdRef.current === sessionId`, but the IPC call itself kept firing until the deadline — burning up to 30 IPC roundtrips on a session the user no longer cared about.
Fix
Check `activeIdRef.current !== sessionId` at the top of each loop iteration AND immediately after the `await`. Bail early so the polling cycle stops, not just the setState. Same guard on the deadline-fallthrough `refreshMessages(sessionId)`.
Invisible when the user stays on the session (common case). Saves bandwidth + CPU on fast session-switch scenarios.
Diff
`1 file changed, 13 insertions(+), 3 deletions(-)` — `apps/desktop/src/renderer/main.tsx:2048-2065`. No conflict with the other in-flight PRs.
Verification
Local disk still at 100%, couldn't run `pnpm install && pnpm test` end-to-end. Static logic change, mechanical pattern.