sidebar turn-state: instant lh:turn-state propagation, poll demoted to backstop

components/session.ts

@@ -61,6 +61,24 @@ export function useChatSession({ chatId, initialMessages, initiallyInFlight }: U
 	// The view + state, derived per model change from the model.
 	const state = useMemo<SessionState>(() => model.getState(), [model, version] as const);
 
+	// THE TURN-STATE BROADCAST (owner, sidebar round 2026-10-02): the same
+	// optimistic machine, propagated — the instant a turn starts locally
+	// (submitted: send, answer, session start, reattach, wake attach) the
+	// sidebar learns it without waiting for its 2.5s poll; at settle the
+	// event clears the row and triggers one immediate refetch. The model
+	// stays pure; this adapter owns the window seam (the lh:chat-renamed
+	// pattern).
+	const prevStatusRef = useRef(state.status);
+	useEffect(() => {
+		const was = prevStatusRef.current;
+		prevStatusRef.current = state.status;
+		if (was === state.status) return;
+		const running = state.status === "submitted" || state.status === "streaming";
+		const wasRunning = was === "submitted" || was === "streaming";
+		if (running === wasRunning) return; // submitted→streaming: still running; error↔ready: not
+		window.dispatchEvent(new CustomEvent("lh:turn-state", { detail: { id: chatId, running } }));
+	}, [state.status, chatId]);
+
 	// The reattach settled terminal → the sync-and-continue seam (chat.tsx).
 	const setReattachSettled = useCallback(
 		(fn: () => void) => {