fix(web): harden timeline sse reconnect lifecycle

apps/web/src/hooks/useTimelineSSE.ts

@@ -15,10 +15,27 @@ export function useTimelineSSE() {
   useEffect(() => {
     let es: EventSource | null = null;
     let reconnectAttempts = 0;
+    let isDisposed = false;
+
+    function scheduleReconnect() {
+      if (isDisposed || reconnectTimeout.current) return;
+      reconnectAttempts++;
+      const delay = Math.min(1000 * Math.pow(2, reconnectAttempts), 30000);
+      reconnectTimeout.current = setTimeout(() => {
+        reconnectTimeout.current = null;
+        if (isDisposed) return;
+        connect();
+      }, delay);
+    }
 
     function connect() {
+      if (isDisposed) return;
       es = new EventSource("/api/sse/timeline");
 
+      es.onopen = () => {
+        reconnectAttempts = 0;
+      };
+
       es.onmessage = (event) => {
         try {
           const data = JSON.parse(event.data as string) as { type: string };
@@ -35,6 +52,7 @@ export function useTimelineSSE() {
               void queryClient.invalidateQueries({ queryKey: [["timeline", "getMyEntriesView"]] });
               void queryClient.invalidateQueries({ queryKey: [["timeline", "getHolidayOverlays"]] });
               void queryClient.invalidateQueries({ queryKey: [["timeline", "getMyHolidayOverlays"]] });
+              void queryClient.invalidateQueries({ queryKey: [["vacation", "list"]] });
               void queryClient.invalidateQueries({ queryKey: [["allocation", "list"]] });
               break;
 
@@ -82,18 +100,18 @@ export function useTimelineSSE() {
 
       es.onerror = () => {
         es?.close();
-        reconnectAttempts++;
-        const delay = Math.min(1000 * Math.pow(2, reconnectAttempts), 30000);
-        reconnectTimeout.current = setTimeout(connect, delay);
+        scheduleReconnect();
       };
     }
 
     connect();
 
     return () => {
+      isDisposed = true;
       es?.close();
       if (reconnectTimeout.current) {
         clearTimeout(reconnectTimeout.current);
+        reconnectTimeout.current = null;
       }
     };
   }, [queryClient]);