Improve messaging and dashboard reliability

src/web/events/express-sse-adapter.ts

@@ -197,6 +197,14 @@ export function createExpressSseHandler(
     }
 
     try {
+      // A first-time subscriber repairs authoritative dashboard snapshots on
+      // open and only needs events published from this point onwards. Replaying
+      // the entire buffer here can overflow the bounded response queue and
+      // force EventSource into a reconnect loop. A genuine reconnect supplies
+      // Last-Event-ID and still receives every buffered event after its cursor.
+      const requestedLastEventId = request.get('Last-Event-ID');
+      const replayCursor = requestedLastEventId
+        ?? options.hub.recent(1).at(-1)?.id;
       subscription = options.hub.subscribe(
         (event) => {
           if (!active) {
@@ -208,7 +216,7 @@ export function createExpressSseHandler(
             close(true);
           }
         },
-        { lastEventId: request.get('Last-Event-ID') },
+        { lastEventId: replayCursor },
       );
     } catch {
       close(true);