Fix dev server hang by reducing log spam and event frequency (#828)

* Changes from fix/dev-server-hang

* fix: Address PR #828 review feedback

- Reset RAF buffer on context changes (worktree switch, dev-server restart)
  to prevent stale output from flushing into new sessions
- Fix high-frequency WebSocket filter to catch auto-mode:event wrapping
  (auto_mode_progress is wrapped in auto-mode:event) and add feature:progress
- Reorder Vite aliases so explicit jsx-runtime entries aren't shadowed by
  the broad /^react(\/|$)/ regex (Vite uses first-match-wins)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: Batch dev server logs and fix React module resolution order

* feat: Add fallback timer for flushing dev server logs in background tabs

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

apps/server/src/index.ts

@@ -598,24 +598,23 @@ wss.on('connection', (ws: WebSocket) => {
 
   // Subscribe to all events and forward to this client
   const unsubscribe = events.subscribe((type, payload) => {
-    logger.info('Event received:', {
+    // Use debug level for high-frequency events to avoid log spam
+    // that causes progressive memory growth and server slowdown
+    const isHighFrequency =
+      type === 'dev-server:output' || type === 'test-runner:output' || type === 'feature:progress';
+    const log = isHighFrequency ? logger.debug.bind(logger) : logger.info.bind(logger);
+
+    log('Event received:', {
       type,
       hasPayload: !!payload,
-      payloadKeys: payload ? Object.keys(payload) : [],
       wsReadyState: ws.readyState,
-      wsOpen: ws.readyState === WebSocket.OPEN,
     });
 
     if (ws.readyState === WebSocket.OPEN) {
       const message = JSON.stringify({ type, payload });
-      logger.info('Sending event to client:', {
-        type,
-        messageLength: message.length,
-        sessionId: (payload as Record<string, unknown>)?.sessionId,
-      });
       ws.send(message);
     } else {
-      logger.info('WARNING: Cannot send event, WebSocket not open. ReadyState:', ws.readyState);
+      logger.warn('Cannot send event, WebSocket not open. ReadyState:', ws.readyState);
     }
   });
 

apps/server/src/services/dev-server-service.ts

@@ -88,9 +88,13 @@ const PORT_PATTERNS: Array<{ pattern: RegExp; description: string }> = [
   },
 ];
 
-// Throttle output to prevent overwhelming WebSocket under heavy load
-const OUTPUT_THROTTLE_MS = 4; // ~250fps max update rate for responsive feedback
-const OUTPUT_BATCH_SIZE = 4096; // Smaller batches for lower latency
+// Throttle output to prevent overwhelming WebSocket under heavy load.
+// 100ms (~10fps) is sufficient for readable log streaming while keeping
+// WebSocket traffic manageable. The previous 4ms rate (~250fps) generated
+// up to 250 events/sec which caused progressive browser slowdown from
+// accumulated console logs, JSON serialization overhead, and React re-renders.
+const OUTPUT_THROTTLE_MS = 100; // ~10fps max update rate
+const OUTPUT_BATCH_SIZE = 8192; // Larger batches to compensate for lower frequency
 
 export interface DevServerInfo {
   worktreePath: string;

apps/server/tests/unit/services/dev-server-event-types.test.ts

@@ -90,8 +90,8 @@ describe('DevServerService Event Types', () => {
 
     // 2. Output & URL Detected
     mockProcess.stdout.emit('data', Buffer.from('Local: http://localhost:5173/\n'));
-    // Throttled output needs a bit of time
-    await new Promise((resolve) => setTimeout(resolve, 100));
+    // Throttled output needs a bit of time (OUTPUT_THROTTLE_MS is 100ms)
+    await new Promise((resolve) => setTimeout(resolve, 250));
     expect(emittedEvents['dev-server:output'].length).toBeGreaterThanOrEqual(1);
     expect(emittedEvents['dev-server:url-detected'].length).toBe(1);
     expect(emittedEvents['dev-server:url-detected'][0].url).toBe('http://localhost:5173/');

apps/ui/src/components/views/board-view/hooks/use-board-features.ts

@@ -32,11 +32,7 @@ export function useBoardFeatures({ currentProject }: UseBoardFeaturesProps) {
   const isRestoring = useIsRestoring();
 
   // Use React Query for features
-  const {
-    data: features = [],
-    isLoading: isQueryLoading,
-    refetch: loadFeatures,
-  } = useFeatures(currentProject?.path);
+  const { data: features = [], isLoading: isQueryLoading } = useFeatures(currentProject?.path);
 
   // Don't report loading while IDB cache restore is in progress —
   // features will appear momentarily once the restore completes.
@@ -159,7 +155,6 @@ export function useBoardFeatures({ currentProject }: UseBoardFeaturesProps) {
     });
 
     return unsubscribe;
-    // eslint-disable-next-line react-hooks/exhaustive-deps -- loadFeatures is a stable ref from React Query
   }, [currentProject]);
 
   // Check for interrupted features on mount

apps/ui/src/components/views/board-view/worktree-panel/hooks/use-dev-server-logs.ts

@@ -74,6 +74,27 @@ export function useDevServerLogs({ worktreePath, autoSubscribe = true }: UseDevS
   // Keep track of whether we've fetched initial logs
   const hasFetchedInitialLogs = useRef(false);
 
+  // Buffer for batching rapid output events into fewer setState calls.
+  // Content accumulates here and is flushed via requestAnimationFrame,
+  // ensuring at most one React re-render per animation frame (~60fps max).
+  // A fallback setTimeout ensures the buffer is flushed even when RAF is
+  // throttled (e.g., when the tab is in the background).
+  const pendingOutputRef = useRef('');
+  const rafIdRef = useRef<number | null>(null);
+  const timerIdRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+
+  const resetPendingOutput = useCallback(() => {
+    if (rafIdRef.current !== null) {
+      cancelAnimationFrame(rafIdRef.current);
+      rafIdRef.current = null;
+    }
+    if (timerIdRef.current !== null) {
+      clearTimeout(timerIdRef.current);
+      timerIdRef.current = null;
+    }
+    pendingOutputRef.current = '';
+  }, []);
+
   /**
    * Fetch buffered logs from the server
    */
@@ -130,6 +151,7 @@ export function useDevServerLogs({ worktreePath, autoSubscribe = true }: UseDevS
    * Clear logs and reset state
    */
   const clearLogs = useCallback(() => {
+    resetPendingOutput();
     setState({
       logs: '',
       logsVersion: 0,
@@ -144,13 +166,19 @@ export function useDevServerLogs({ worktreePath, autoSubscribe = true }: UseDevS
       serverError: null,
     });
     hasFetchedInitialLogs.current = false;
-  }, []);
+  }, [resetPendingOutput]);
+
+  const flushPendingOutput = useCallback(() => {
+    // Clear both scheduling handles to prevent duplicate flushes
+    rafIdRef.current = null;
+    if (timerIdRef.current !== null) {
+      clearTimeout(timerIdRef.current);
+      timerIdRef.current = null;
+    }
+    const content = pendingOutputRef.current;
+    if (!content) return;
+    pendingOutputRef.current = '';
 
-  /**
-   * Append content to logs, enforcing a maximum buffer size to prevent
-   * unbounded memory growth and progressive UI lag.
-   */
-  const appendLogs = useCallback((content: string) => {
     setState((prev) => {
       const combined = prev.logs + content;
       const didTrim = combined.length > MAX_LOG_BUFFER_SIZE;
@@ -170,6 +198,48 @@ export function useDevServerLogs({ worktreePath, autoSubscribe = true }: UseDevS
     });
   }, []);
 
+  /**
+   * Append content to logs, enforcing a maximum buffer size to prevent
+   * unbounded memory growth and progressive UI lag.
+   *
+   * Uses requestAnimationFrame to batch rapid output events into at most
+   * one React state update per frame, preventing excessive re-renders.
+   * A fallback setTimeout(250ms) ensures the buffer is flushed even when
+   * RAF is throttled (e.g., when the tab is in the background).
+   * If the pending buffer reaches MAX_LOG_BUFFER_SIZE, flushes immediately
+   * to prevent unbounded memory growth.
+   */
+  const appendLogs = useCallback(
+    (content: string) => {
+      pendingOutputRef.current += content;
+
+      // Flush immediately if buffer has reached the size limit
+      if (pendingOutputRef.current.length >= MAX_LOG_BUFFER_SIZE) {
+        flushPendingOutput();
+        return;
+      }
+
+      // Schedule a RAF flush if not already scheduled
+      if (rafIdRef.current === null) {
+        rafIdRef.current = requestAnimationFrame(flushPendingOutput);
+      }
+
+      // Schedule a fallback timer flush if not already scheduled,
+      // to handle cases where RAF is throttled (background tab)
+      if (timerIdRef.current === null) {
+        timerIdRef.current = setTimeout(flushPendingOutput, 250);
+      }
+    },
+    [flushPendingOutput]
+  );
+
+  // Clean up pending RAF on unmount to prevent state updates after unmount
+  useEffect(() => {
+    return () => {
+      resetPendingOutput();
+    };
+  }, [resetPendingOutput]);
+
   // Fetch initial logs when worktreePath changes
   useEffect(() => {
     if (worktreePath && autoSubscribe) {
@@ -196,6 +266,7 @@ export function useDevServerLogs({ worktreePath, autoSubscribe = true }: UseDevS
 
       switch (event.type) {
         case 'dev-server:started': {
+          resetPendingOutput();
           const { payload } = event;
           logger.info('Dev server started:', payload);
           setState((prev) => ({
@@ -245,7 +316,7 @@ export function useDevServerLogs({ worktreePath, autoSubscribe = true }: UseDevS
     });
 
     return unsubscribe;
-  }, [worktreePath, autoSubscribe, appendLogs]);
+  }, [worktreePath, autoSubscribe, appendLogs, resetPendingOutput]);
 
   return {
     ...state,

apps/ui/src/components/views/board-view/worktree-panel/hooks/use-dev-servers.ts

@@ -4,13 +4,17 @@ import { getElectronAPI } from '@/lib/electron';
 import { normalizePath } from '@/lib/utils';
 import { toast } from 'sonner';
 import type { DevServerInfo, WorktreeInfo } from '../types';
+import { useEventRecencyStore } from '@/hooks/use-event-recency';
 
 const logger = createLogger('DevServers');
 
 // Timeout (ms) for port detection before showing a warning to the user
 const PORT_DETECTION_TIMEOUT_MS = 30_000;
-// Interval (ms) for periodic state reconciliation with the backend
-const STATE_RECONCILE_INTERVAL_MS = 5_000;
+// Interval (ms) for periodic state reconciliation with the backend.
+// 30 seconds is sufficient since WebSocket events handle real-time updates;
+// reconciliation is only a fallback for missed events (PWA restart, WS gaps).
+// The previous 5-second interval added unnecessary HTTP pressure.
+const STATE_RECONCILE_INTERVAL_MS = 30_000;
 
 interface UseDevServersOptions {
   projectPath: string;
@@ -322,12 +326,24 @@ export function useDevServers({ projectPath }: UseDevServersOptions) {
     return () => clearInterval(intervalId);
   }, [clearPortDetectionTimer, startPortDetectionTimer]);
 
+  // Record global events so smart polling knows WebSocket is healthy.
+  // Without this, dev-server events don't suppress polling intervals,
+  // causing all queries (features, worktrees, running-agents) to poll
+  // at their default rates even though the WebSocket is actively connected.
+  const recordGlobalEvent = useEventRecencyStore((state) => state.recordGlobalEvent);
+
   // Subscribe to all dev server lifecycle events for reactive state updates
   useEffect(() => {
     const api = getElectronAPI();
     if (!api?.worktree?.onDevServerLogEvent) return;
 
     const unsubscribe = api.worktree.onDevServerLogEvent((event) => {
+      // Record that WS is alive (but only for lifecycle events, not output -
+      // output fires too frequently and would trigger unnecessary store updates)
+      if (event.type !== 'dev-server:output') {
+        recordGlobalEvent();
+      }
+
       if (event.type === 'dev-server:starting') {
         const { worktreePath } = event.payload;
         const key = normalizePath(worktreePath);
@@ -424,7 +440,7 @@ export function useDevServers({ projectPath }: UseDevServersOptions) {
     });
 
     return unsubscribe;
-  }, [clearPortDetectionTimer, startPortDetectionTimer]);
+  }, [clearPortDetectionTimer, startPortDetectionTimer, recordGlobalEvent]);
 
   // Cleanup all port detection timers on unmount
   useEffect(() => {

apps/ui/src/lib/http-api-client.ts

@@ -923,17 +923,20 @@ export class HttpApiClient implements ElectronAPI {
       this.ws.onmessage = (event) => {
         try {
           const data = JSON.parse(event.data);
-          logger.info(
-            'WebSocket message:',
-            data.type,
-            'hasPayload:',
-            !!data.payload,
-            'callbacksRegistered:',
-            this.eventCallbacks.has(data.type)
-          );
+          // Only log non-high-frequency events to avoid progressive memory growth
+          // from accumulated console entries. High-frequency events (dev-server output,
+          // test runner output, agent progress) fire 10+ times/sec and would generate
+          // thousands of console entries per minute.
+          const isHighFrequency =
+            data.type === 'dev-server:output' ||
+            data.type === 'test-runner:output' ||
+            data.type === 'feature:progress' ||
+            (data.type === 'auto-mode:event' && data.payload?.type === 'auto_mode_progress');
+          if (!isHighFrequency) {
+            logger.info('WebSocket message:', data.type);
+          }
           const callbacks = this.eventCallbacks.get(data.type);
           if (callbacks) {
-            logger.info('Dispatching to', callbacks.size, 'callbacks');
             callbacks.forEach((cb) => cb(data.payload));
           }
         } catch (error) {

apps/ui/vite.config.mts

@@ -238,24 +238,36 @@ export default defineConfig(({ command }) => {
       // Inject build hash into sw.js CACHE_NAME for automatic cache busting
       swCacheBuster(),
     ],
+    // Keep Vite dep-optimization cache local to apps/ui so each worktree gets
+    // its own pre-bundled dependencies. Shared cache state across worktrees can
+    // produce duplicate React instances (notably with @xyflow/react) and trigger
+    // "Invalid hook call" in the graph view.
+    cacheDir: path.resolve(__dirname, 'node_modules/.vite'),
     resolve: {
       alias: [
         { find: '@', replacement: path.resolve(__dirname, './src') },
         // Force ALL React imports (including from nested deps like zustand@4 inside
-        // @xyflow/react) to resolve to the single copy in the workspace root node_modules.
-        // This prevents "Cannot read properties of null (reading 'useState')" caused by
-        // react-dom setting the hooks dispatcher on one React instance while component
-        // code reads it from a different instance.
+        // @xyflow/react) to resolve to a single copy.
+        // Explicit subpath aliases must come BEFORE the broad regex so Vite's
+        // first-match-wins resolution applies the specific match first.
         {
           find: /^react-dom(\/|$)/,
           replacement: path.resolve(__dirname, '../../node_modules/react-dom') + '/',
         },
+        {
+          find: 'react/jsx-runtime',
+          replacement: path.resolve(__dirname, '../../node_modules/react/jsx-runtime.js'),
+        },
+        {
+          find: 'react/jsx-dev-runtime',
+          replacement: path.resolve(__dirname, '../../node_modules/react/jsx-dev-runtime.js'),
+        },
         {
           find: /^react(\/|$)/,
           replacement: path.resolve(__dirname, '../../node_modules/react') + '/',
         },
       ],
-      dedupe: ['react', 'react-dom'],
+      dedupe: ['react', 'react-dom', 'zustand', 'use-sync-external-store', '@xyflow/react'],
     },
     server: {
       host: process.env.HOST || '0.0.0.0',
@@ -355,8 +367,12 @@ export default defineConfig(({ command }) => {
       include: [
         'react',
         'react-dom',
+        'react/jsx-runtime',
+        'react/jsx-dev-runtime',
         'use-sync-external-store',
+        'use-sync-external-store/shim',
         'use-sync-external-store/shim/with-selector',
+        'zustand',
         '@xyflow/react',
       ],
     },