Prevent UI from sticking while running

mp1/frontend/app.js

@@ -5,6 +5,8 @@
     selectedDocIds: 'pluto.selectedDocIds',
     detailLevel: 'pluto.detailLevel',
   };
+  const RUN_TIMEOUT_MS = 180000;
+  const BENCH_TIMEOUT_MS = 180000;
 
   const stages = ['route', 'extract', 'merge', 'evidence_check'];
   const stageEls = {};
@@ -161,18 +163,18 @@
     pipelineRunning = true;
     const sessionId = createSessionId();
     const queryTimestamp = Date.now();
-    activeSessionId = sessionId;
-    syncControls();
-    runBtn.innerHTML = '<span class="spinner"></span> Running...';
-    resetUI();
 
     try {
+      activeSessionId = sessionId;
+      syncControls();
+      runBtn.innerHTML = '<span class="spinner"></span> Running...';
+      resetUI();
       listenSSE(sessionId);
-      const response = await fetch('/api/run', {
+      const response = await fetchWithTimeout('/api/run', {
         method: 'POST',
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify(buildQueryPayload(query, sessionId, queryTimestamp)),
-      });
+      }, RUN_TIMEOUT_MS, 'Pipeline request timed out. The server may still be working; try again or refresh the app.');
       const data = await parseJsonResponse(response, 'Server returned an invalid response');
       activeSessionId = data.session_id || sessionId;
       if (!response.ok || data.error) {
@@ -207,11 +209,11 @@
     benchBody.innerHTML = '<div id="benchLoader" class="bench-loader"><span class="spinner"></span> Running side-by-side comparison...</div>';
 
     try {
-      const response = await fetch('/api/compare', {
+      const response = await fetchWithTimeout('/api/compare', {
         method: 'POST',
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify(buildQueryPayload(query)),
-      });
+      }, BENCH_TIMEOUT_MS, 'Benchmark request timed out. Try again after the server finishes the current work.');
       const data = await parseJsonResponse(response, 'Benchmark returned an invalid response');
       if (!response.ok || data.error) {
         throw new Error(data.error || `Benchmark error: ${response.status}`);
@@ -901,6 +903,22 @@
     }
   }
 
+  async function fetchWithTimeout(url, options = {}, timeoutMs = 120000, timeoutMessage = 'Request timed out') {
+    const controller = new AbortController();
+    const timeoutId = window.setTimeout(() => controller.abort(), timeoutMs);
+
+    try {
+      return await fetch(url, { ...options, signal: controller.signal });
+    } catch (error) {
+      if (error && error.name === 'AbortError') {
+        throw new Error(timeoutMessage);
+      }
+      throw error;
+    } finally {
+      window.clearTimeout(timeoutId);
+    }
+  }
+
   function formatSize(bytes) {
     if (bytes < 1024) {
       return `${bytes} B`;

mp1/frontend/index.html

@@ -185,7 +185,7 @@
     <span>Pluto v2 Pipeline | Deterministic routing | Real model switching | Evidence checking</span>
   </footer>
 
-  <script src="/static/app.js?v=5"></script>
+  <script src="/static/app.js?v=6"></script>
 </body>
 
 </html>