diff --git a/packages/dashboard/src/routes.ts b/packages/dashboard/src/routes.ts
index 2f30022ef..34c2d23c2 100644
--- a/packages/dashboard/src/routes.ts
+++ b/packages/dashboard/src/routes.ts
@@ -9713,6 +9713,18 @@ export function createApiRoutes(store: TaskStore, options?: ServerOptions): Rout
           }
         }
         // Don't return — subscribe to continue receiving events (thinking, next question, etc.)
+      } else if (lastEventId === undefined) {
+        // First-connect catch-up for a session that is still generating its
+        // first response: there is no question or summary yet, but the agent
+        // may already be streaming thinking deltas into the buffer faster
+        // than the client could establish the SSE connection. Replay every
+        // buffered event so the user sees the running thinking output from
+        // the start of generation, especially on slower mobile connections.
+        const buffered = planningStreamManager.getBufferedEvents(sessionId, 0);
+        if (!replayBufferedSSE(res, buffered)) {
+          res.end();
+          return;
+        }
       }
 
       // Subscribe to session events