diff --git a/apps/ui/src/components/views/board-view/hooks/use-board-actions.ts b/apps/ui/src/components/views/board-view/hooks/use-board-actions.ts
index f2e84d14a..2188b9f2a 100644
--- a/apps/ui/src/components/views/board-view/hooks/use-board-actions.ts
+++ b/apps/ui/src/components/views/board-view/hooks/use-board-actions.ts
@@ -1,6 +1,5 @@
 // @ts-nocheck - feature update logic with partial updates and image/file handling
 import { useCallback } from 'react';
-import { useQueryClient } from '@tanstack/react-query';
 import {
   Feature,
   FeatureImage,
@@ -18,7 +17,10 @@ import { useVerifyFeature, useResumeFeature } from '@/hooks/mutations';
 import { truncateDescription } from '@/lib/utils';
 import { getBlockingDependencies } from '@automaker/dependency-resolver';
 import { createLogger } from '@automaker/utils/logger';
-import { queryKeys } from '@/lib/query-keys';
+import {
+  markFeatureTransitioning,
+  unmarkFeatureTransitioning,
+} from '@/lib/feature-transition-state';
 
 const logger = createLogger('BoardActions');
 
@@ -116,8 +118,6 @@ export function useBoardActions({
   currentWorktreeBranch,
   stopFeature,
 }: UseBoardActionsProps) {
-  const queryClient = useQueryClient();
-
   // IMPORTANT: Use individual selectors instead of bare useAppStore() to prevent
   // subscribing to the entire store. Bare useAppStore() causes the host component
   // (BoardView) to re-render on EVERY store change, which cascades through effects
@@ -125,7 +125,6 @@ export function useBoardActions({
   const addFeature = useAppStore((s) => s.addFeature);
   const updateFeature = useAppStore((s) => s.updateFeature);
   const removeFeature = useAppStore((s) => s.removeFeature);
-  const moveFeature = useAppStore((s) => s.moveFeature);
   const worktreesEnabled = useAppStore((s) => s.useWorktrees);
   const enableDependencyBlocking = useAppStore((s) => s.enableDependencyBlocking);
   const skipVerificationInAutoMode = useAppStore((s) => s.skipVerificationInAutoMode);
@@ -707,8 +706,7 @@ export function useBoardActions({
       try {
         const result = await verifyFeatureMutation.mutateAsync(feature.id);
         if (result.passes) {
-          // Immediately move card to verified column (optimistic update)
-          moveFeature(feature.id, 'verified');
+          // persistFeatureUpdate handles the optimistic RQ cache update internally
           persistFeatureUpdate(feature.id, {
             status: 'verified',
             justFinishedAt: undefined,
@@ -725,7 +723,7 @@ export function useBoardActions({
         // Error toast is already shown by the mutation's onError handler
       }
     },
-    [currentProject, verifyFeatureMutation, moveFeature, persistFeatureUpdate]
+    [currentProject, verifyFeatureMutation, persistFeatureUpdate]
   );
 
   const handleResumeFeature = useCallback(
@@ -742,7 +740,6 @@ export function useBoardActions({
 
   const handleManualVerify = useCallback(
     (feature: Feature) => {
-      moveFeature(feature.id, 'verified');
       persistFeatureUpdate(feature.id, {
         status: 'verified',
         justFinishedAt: undefined,
@@ -751,7 +748,7 @@ export function useBoardActions({
         description: `Marked as verified: ${truncateDescription(feature.description)}`,
       });
     },
-    [moveFeature, persistFeatureUpdate]
+    [persistFeatureUpdate]
   );
 
   const handleMoveBackToInProgress = useCallback(
@@ -760,13 +757,12 @@ export function useBoardActions({
         status: 'in_progress' as const,
         startedAt: new Date().toISOString(),
       };
-      updateFeature(feature.id, updates);
       persistFeatureUpdate(feature.id, updates);
       toast.info('Feature moved back', {
         description: `Moved back to In Progress: ${truncateDescription(feature.description)}`,
       });
     },
-    [updateFeature, persistFeatureUpdate]
+    [persistFeatureUpdate]
   );
 
   const handleOpenFollowUp = useCallback(
@@ -885,7 +881,6 @@ export function useBoardActions({
         );
 
         if (result.success) {
-          moveFeature(feature.id, 'verified');
           persistFeatureUpdate(feature.id, { status: 'verified' });
           toast.success('Feature committed', {
             description: `Committed and verified: ${truncateDescription(feature.description)}`,
@@ -907,7 +902,7 @@ export function useBoardActions({
         await loadFeatures();
       }
     },
-    [currentProject, moveFeature, persistFeatureUpdate, loadFeatures, onWorktreeCreated]
+    [currentProject, persistFeatureUpdate, loadFeatures, onWorktreeCreated]
   );
 
   const handleMergeFeature = useCallback(
@@ -951,17 +946,12 @@ export function useBoardActions({
 
   const handleCompleteFeature = useCallback(
     (feature: Feature) => {
-      const updates = {
-        status: 'completed' as const,
-      };
-      updateFeature(feature.id, updates);
-      persistFeatureUpdate(feature.id, updates);
-
+      persistFeatureUpdate(feature.id, { status: 'completed' as const });
       toast.success('Feature completed', {
         description: `Archived: ${truncateDescription(feature.description)}`,
       });
     },
-    [updateFeature, persistFeatureUpdate]
+    [persistFeatureUpdate]
   );
 
   const handleUnarchiveFeature = useCallback(
@@ -978,11 +968,7 @@ export function useBoardActions({
           (projectPath ? isPrimaryWorktreeBranch(projectPath, currentWorktreeBranch) : true)
         : featureBranch === currentWorktreeBranch;
 
-      const updates: Partial<Feature> = {
-        status: 'verified' as const,
-      };
-      updateFeature(feature.id, updates);
-      persistFeatureUpdate(feature.id, updates);
+      persistFeatureUpdate(feature.id, { status: 'verified' as const });
 
       if (willBeVisibleOnCurrentView) {
         toast.success('Feature restored', {
@@ -994,13 +980,7 @@ export function useBoardActions({
         });
       }
     },
-    [
-      updateFeature,
-      persistFeatureUpdate,
-      currentWorktreeBranch,
-      projectPath,
-      isPrimaryWorktreeBranch,
-    ]
+    [persistFeatureUpdate, currentWorktreeBranch, projectPath, isPrimaryWorktreeBranch]
   );
 
   const handleViewOutput = useCallback(
@@ -1031,6 +1011,13 @@ export function useBoardActions({
 
   const handleForceStopFeature = useCallback(
     async (feature: Feature) => {
+      // Mark this feature as transitioning so WebSocket-driven query invalidation
+      // (useAutoModeQueryInvalidation) skips redundant cache invalidations while
+      // persistFeatureUpdate is handling the optimistic update. Without this guard,
+      // auto_mode_error / auto_mode_stopped WS events race with the optimistic
+      // update and cause cache flip-flops that cascade through useBoardColumnFeatures,
+      // triggering React error #185 on mobile.
+      markFeatureTransitioning(feature.id);
       try {
         await stopFeature(feature.id);
 
@@ -1048,25 +1035,11 @@ export function useBoardActions({
           removeRunningTaskFromAllWorktrees(currentProject.id, feature.id);
         }
 
-        // Optimistically update the React Query features cache so the board
-        // moves the card immediately. Without this, the card stays in
-        // "in_progress" until the next poll cycle (30s) because the async
-        // refetch races with the persistFeatureUpdate write.
-        if (currentProject) {
-          queryClient.setQueryData(
-            queryKeys.features.all(currentProject.path),
-            (oldFeatures: Feature[] | undefined) => {
-              if (!oldFeatures) return oldFeatures;
-              return oldFeatures.map((f) =>
-                f.id === feature.id ? { ...f, status: targetStatus } : f
-              );
-            }
-          );
-        }
-
         if (targetStatus !== feature.status) {
-          moveFeature(feature.id, targetStatus);
-          // Must await to ensure file is written before user can restart
+          // persistFeatureUpdate handles the optimistic RQ cache update, the
+          // Zustand store update (on server response), and the final cache
+          // invalidation internally — no need for separate queryClient.setQueryData
+          // or moveFeature calls which would cause redundant re-renders.
           await persistFeatureUpdate(feature.id, { status: targetStatus });
         }
 
@@ -1083,9 +1056,15 @@ export function useBoardActions({
         toast.error('Failed to stop agent', {
           description: error instanceof Error ? error.message : 'An error occurred',
         });
+      } finally {
+        // Delay unmarking so the refetch triggered by persistFeatureUpdate's
+        // invalidateQueries() has time to settle before WS-driven invalidations
+        // are allowed through again. Without this, a WS event arriving during
+        // the refetch window would trigger a conflicting invalidation.
+        setTimeout(() => unmarkFeatureTransitioning(feature.id), 500);
       }
     },
-    [stopFeature, moveFeature, persistFeatureUpdate, currentProject, queryClient]
+    [stopFeature, persistFeatureUpdate, currentProject]
   );
 
   const handleStartNextFeatures = useCallback(async () => {
diff --git a/apps/ui/src/components/views/board-view/hooks/use-board-column-features.ts b/apps/ui/src/components/views/board-view/hooks/use-board-column-features.ts
index 73439ee9d..82965e95d 100644
--- a/apps/ui/src/components/views/board-view/hooks/use-board-column-features.ts
+++ b/apps/ui/src/components/views/board-view/hooks/use-board-column-features.ts
@@ -1,5 +1,5 @@
 // @ts-nocheck - column filtering logic with dependency resolution and status mapping
-import { useMemo, useCallback, useEffect, useRef } from 'react';
+import { useMemo, useCallback, useEffect } from 'react';
 import { Feature, useAppStore } from '@/store/app-store';
 import {
   createFeatureMap,
@@ -177,9 +177,6 @@ export function useBoardColumnFeatures({
     (state) => state.clearRecentlyCompletedFeatures
   );
 
-  // Track previous feature IDs to detect when features list has been refreshed
-  const prevFeatureIdsRef = useRef<Set<string>>(new Set());
-
   // Clear recently completed features when the cache refreshes with updated statuses.
   //
   // RACE CONDITION SCENARIO THIS PREVENTS:
@@ -193,12 +190,16 @@ export function useBoardColumnFeatures({
   //
   // When the refetch completes with fresh data (status='verified'/'completed'),
   // this effect clears the recentlyCompletedFeatures set since it's no longer needed.
+  // Clear recently completed features when the cache refreshes with updated statuses.
+  // IMPORTANT: Only depend on `features` (not `recentlyCompletedFeatures`) to avoid a
+  // re-trigger loop where clearing the set creates a new reference that re-fires this effect.
+  // Read recentlyCompletedFeatures from the store directly to get the latest value without
+  // subscribing to it as a dependency.
   useEffect(() => {
-    const currentIds = new Set(features.map((f) => f.id));
+    const currentRecentlyCompleted = useAppStore.getState().recentlyCompletedFeatures;
+    if (currentRecentlyCompleted.size === 0) return;
 
-    // Check if any recently completed features now have terminal statuses in the new data
-    // If so, we can clear the tracking since the cache is now fresh
-    const hasUpdatedStatus = Array.from(recentlyCompletedFeatures).some((featureId) => {
+    const hasUpdatedStatus = Array.from(currentRecentlyCompleted).some((featureId) => {
       const feature = features.find((f) => f.id === featureId);
       return feature && (feature.status === 'verified' || feature.status === 'completed');
     });
@@ -206,9 +207,7 @@ export function useBoardColumnFeatures({
     if (hasUpdatedStatus) {
       clearRecentlyCompletedFeatures();
     }
-
-    prevFeatureIdsRef.current = currentIds;
-  }, [features, recentlyCompletedFeatures, clearRecentlyCompletedFeatures]);
+  }, [features, clearRecentlyCompletedFeatures]);
 
   // Memoize column features to prevent unnecessary re-renders
   const columnFeaturesMap = useMemo(() => {
diff --git a/apps/ui/src/components/views/board-view/hooks/use-board-drag-drop.ts b/apps/ui/src/components/views/board-view/hooks/use-board-drag-drop.ts
index b847be820..cd0cc1e57 100644
--- a/apps/ui/src/components/views/board-view/hooks/use-board-drag-drop.ts
+++ b/apps/ui/src/components/views/board-view/hooks/use-board-drag-drop.ts
@@ -38,7 +38,6 @@ export function useBoardDragDrop({
   // subscribing to the entire store. Bare useAppStore() causes the host component
   // (BoardView) to re-render on EVERY store change, which cascades through effects
   // and triggers React error #185 (maximum update depth exceeded).
-  const moveFeature = useAppStore((s) => s.moveFeature);
   const updateFeature = useAppStore((s) => s.updateFeature);
 
   // Note: getOrCreateWorktreeForFeature removed - worktrees are now created server-side
@@ -207,7 +206,8 @@ export function useBoardDragDrop({
       if (targetStatus === draggedFeature.status) return;
 
       // Handle different drag scenarios
-      // Note: Worktrees are created server-side at execution time based on feature.branchName
+      // Note: persistFeatureUpdate handles optimistic RQ cache update internally,
+      // so no separate moveFeature() call is needed.
       if (draggedFeature.status === 'backlog' || draggedFeature.status === 'merge_conflict') {
         // From backlog
         if (targetStatus === 'in_progress') {
@@ -215,7 +215,6 @@ export function useBoardDragDrop({
           // Server will derive workDir from feature.branchName
           await handleStartImplementation(draggedFeature);
         } else {
-          moveFeature(featureId, targetStatus);
           persistFeatureUpdate(featureId, { status: targetStatus });
         }
       } else if (draggedFeature.status === 'waiting_approval') {
@@ -223,7 +222,6 @@ export function useBoardDragDrop({
         // NOTE: This check must come BEFORE skipTests check because waiting_approval
         // features often have skipTests=true, and we want status-based handling first
         if (targetStatus === 'verified') {
-          moveFeature(featureId, 'verified');
           // Clear justFinishedAt timestamp when manually verifying via drag
           persistFeatureUpdate(featureId, {
             status: 'verified',
@@ -237,7 +235,6 @@ export function useBoardDragDrop({
           });
         } else if (targetStatus === 'backlog') {
           // Allow moving waiting_approval cards back to backlog
-          moveFeature(featureId, 'backlog');
           // Clear justFinishedAt timestamp when moving back to backlog
           persistFeatureUpdate(featureId, {
             status: 'backlog',
@@ -269,7 +266,6 @@ export function useBoardDragDrop({
               });
             }
           }
-          moveFeature(featureId, 'backlog');
           persistFeatureUpdate(featureId, { status: 'backlog' });
           toast.info(
             isRunningTask
@@ -291,7 +287,6 @@ export function useBoardDragDrop({
           return;
         } else if (targetStatus === 'verified' && draggedFeature.skipTests) {
           // Manual verify via drag (only for skipTests features)
-          moveFeature(featureId, 'verified');
           persistFeatureUpdate(featureId, { status: 'verified' });
           toast.success('Feature verified', {
             description: `Marked as verified: ${draggedFeature.description.slice(
@@ -304,7 +299,6 @@ export function useBoardDragDrop({
         // skipTests feature being moved between verified and waiting_approval
         if (targetStatus === 'waiting_approval' && draggedFeature.status === 'verified') {
           // Move verified feature back to waiting_approval
-          moveFeature(featureId, 'waiting_approval');
           persistFeatureUpdate(featureId, { status: 'waiting_approval' });
           toast.info('Feature moved back', {
             description: `Moved back to Waiting Approval: ${draggedFeature.description.slice(
@@ -314,7 +308,6 @@ export function useBoardDragDrop({
           });
         } else if (targetStatus === 'backlog') {
           // Allow moving skipTests cards back to backlog (from verified)
-          moveFeature(featureId, 'backlog');
           persistFeatureUpdate(featureId, { status: 'backlog' });
           toast.info('Feature moved to backlog', {
             description: `Moved to Backlog: ${draggedFeature.description.slice(
@@ -327,7 +320,6 @@ export function useBoardDragDrop({
         // Handle verified TDD (non-skipTests) features being moved back
         if (targetStatus === 'waiting_approval') {
           // Move verified feature back to waiting_approval
-          moveFeature(featureId, 'waiting_approval');
           persistFeatureUpdate(featureId, { status: 'waiting_approval' });
           toast.info('Feature moved back', {
             description: `Moved back to Waiting Approval: ${draggedFeature.description.slice(
@@ -337,7 +329,6 @@ export function useBoardDragDrop({
           });
         } else if (targetStatus === 'backlog') {
           // Allow moving verified cards back to backlog
-          moveFeature(featureId, 'backlog');
           persistFeatureUpdate(featureId, { status: 'backlog' });
           toast.info('Feature moved to backlog', {
             description: `Moved to Backlog: ${draggedFeature.description.slice(
@@ -351,7 +342,6 @@ export function useBoardDragDrop({
     [
       features,
       runningAutoTasks,
-      moveFeature,
       updateFeature,
       persistFeatureUpdate,
       handleStartImplementation,
diff --git a/apps/ui/src/components/views/board-view/hooks/use-board-features.ts b/apps/ui/src/components/views/board-view/hooks/use-board-features.ts
index 203b30173..944472345 100644
--- a/apps/ui/src/components/views/board-view/hooks/use-board-features.ts
+++ b/apps/ui/src/components/views/board-view/hooks/use-board-features.ts
@@ -87,37 +87,22 @@ export function useBoardFeatures({ currentProject }: UseBoardFeaturesProps) {
   );
 
   // Subscribe to auto mode events for notifications (ding sound, toasts)
-  // Note: Query invalidation is handled by useAutoModeQueryInvalidation in the root
+  // Note: Query invalidation is handled by useAutoModeQueryInvalidation in the root.
+  // Note: removeRunningTask is handled by useAutoMode — do NOT duplicate it here,
+  // as duplicate Zustand mutations cause re-render cascades (React error #185).
   useEffect(() => {
     const api = getElectronAPI();
     if (!api?.autoMode || !currentProject) return;
 
-    const { removeRunningTask } = useAppStore.getState();
-    const projectId = currentProject.id;
     const projectPath = currentProject.path;
 
     const unsubscribe = api.autoMode.onEvent((event) => {
       // Check if event is for the current project by matching projectPath
       const eventProjectPath = ('projectPath' in event && event.projectPath) as string | undefined;
       if (eventProjectPath && eventProjectPath !== projectPath) {
-        // Event is for a different project, ignore it
-        logger.debug(
-          `Ignoring auto mode event for different project: ${eventProjectPath} (current: ${projectPath})`
-        );
         return;
       }
 
-      // Use event's projectPath or projectId if available, otherwise use current project
-      // Board view only reacts to events for the currently selected project
-      const eventProjectId = ('projectId' in event && event.projectId) || projectId;
-
-      // NOTE: auto_mode_feature_start and auto_mode_feature_complete are NOT handled here
-      // for feature list reloading. That is handled by useAutoModeQueryInvalidation which
-      // invalidates the features.all query on those events. Duplicate invalidation here
-      // caused a re-render cascade through DndContext that triggered React error #185
-      // (maximum update depth exceeded), crashing the board view with an infinite spinner
-      // when a new feature was added and moved to in_progress.
-
       if (event.type === 'auto_mode_feature_complete') {
         // Play ding sound when feature is done (unless muted)
         const { muteDoneSound } = useAppStore.getState();
@@ -126,14 +111,7 @@ export function useBoardFeatures({ currentProject }: UseBoardFeaturesProps) {
           audio.play().catch((err) => logger.warn('Could not play ding sound:', err));
         }
       } else if (event.type === 'auto_mode_error') {
-        // Remove from running tasks
-        if (event.featureId) {
-          const eventBranchName =
-            'branchName' in event && event.branchName !== undefined ? event.branchName : null;
-          removeRunningTask(eventProjectId, eventBranchName, event.featureId);
-        }
-
-        // Show error toast
+        // Show error toast (removeRunningTask is handled by useAutoMode, not here)
         const isAuthError =
           event.errorType === 'authentication' ||
           (event.error &&
diff --git a/apps/ui/src/components/views/board-view/kanban-board.tsx b/apps/ui/src/components/views/board-view/kanban-board.tsx
index 446ac08ff..f3b1c6034 100644
--- a/apps/ui/src/components/views/board-view/kanban-board.tsx
+++ b/apps/ui/src/components/views/board-view/kanban-board.tsx
@@ -281,6 +281,10 @@ function VirtualizedList<Item extends VirtualListItem>({
   );
 }
 
+// Stable empty Set to use as default prop value. Using `new Set()` inline in
+// the destructuring creates a new reference on every render, defeating memo.
+const EMPTY_FEATURE_IDS = new Set<string>();
+
 export const KanbanBoard = memo(function KanbanBoard({
   activeFeature,
   getColumnFeatures,
@@ -317,7 +321,7 @@ export const KanbanBoard = memo(function KanbanBoard({
   onOpenPipelineSettings,
   isSelectionMode = false,
   selectionTarget = null,
-  selectedFeatureIds = new Set(),
+  selectedFeatureIds = EMPTY_FEATURE_IDS,
   onToggleFeatureSelection,
   onToggleSelectionMode,
   onAiSuggest,
diff --git a/apps/ui/src/hooks/use-auto-mode.ts b/apps/ui/src/hooks/use-auto-mode.ts
index faf123437..25772b68f 100644
--- a/apps/ui/src/hooks/use-auto-mode.ts
+++ b/apps/ui/src/hooks/use-auto-mode.ts
@@ -22,6 +22,8 @@ function arraysEqual(a: string[], b: string[]): boolean {
   return a.every((id) => set.has(id));
 }
 const AUTO_MODE_POLLING_INTERVAL = 30000;
+// Stable empty array reference to avoid re-renders from `[] !== []`
+const EMPTY_TASKS: string[] = [];
 
 /**
  * Generate a worktree key for session storage
@@ -77,8 +79,12 @@ function isPlanApprovalEvent(
  * @param worktree - Optional worktree info. If not provided, uses main worktree (branchName = null)
  */
 export function useAutoMode(worktree?: WorktreeInfo) {
+  // Subscribe to stable action functions and scalar state via useShallow.
+  // IMPORTANT: Do NOT subscribe to autoModeByWorktree here. That object gets a
+  // new reference on every Zustand mutation to ANY worktree, which would re-render
+  // every useAutoMode consumer on every store change. Instead, we subscribe to the
+  // specific worktree's state below using a targeted selector.
   const {
-    autoModeByWorktree,
     setAutoModeRunning,
     addRunningTask,
     removeRunningTask,
@@ -93,7 +99,6 @@ export function useAutoMode(worktree?: WorktreeInfo) {
     addRecentlyCompletedFeature,
   } = useAppStore(
     useShallow((state) => ({
-      autoModeByWorktree: state.autoModeByWorktree,
       setAutoModeRunning: state.setAutoModeRunning,
       addRunningTask: state.addRunningTask,
       removeRunningTask: state.removeRunningTask,
@@ -144,41 +149,109 @@ export function useAutoMode(worktree?: WorktreeInfo) {
     [projects]
   );
 
-  // Get worktree-specific auto mode state
+  // Get worktree-specific auto mode state using a TARGETED selector with
+  // VALUE-BASED equality. This is critical for preventing cascading re-renders
+  // in board view, where DndContext amplifies every parent re-render.
+  //
+  // Why value-based equality matters: Every Zustand `set()` call (including
+  // `addAutoModeActivity` which fires on every WS event) triggers all subscriber
+  // selectors to re-run. Even our targeted selector that reads a specific key
+  // would return a new object reference (from the spread in `removeRunningTask`
+  // etc.), causing a re-render even when the actual values haven't changed.
+  // By extracting primitives and comparing with a custom equality function,
+  // we only re-render when isRunning/runningTasks/maxConcurrency actually change.
   const projectId = currentProject?.id;
-  const worktreeAutoModeState = useMemo(() => {
-    if (!projectId)
+  const worktreeKey = useMemo(
+    () => (projectId ? getWorktreeKey(projectId, branchName) : null),
+    [projectId, branchName, getWorktreeKey]
+  );
+
+  // Subscribe to this specific worktree's state using useShallow.
+  // useShallow compares each property of the returned object with Object.is,
+  // so primitive properties (isRunning: boolean, maxConcurrency: number) are
+  // naturally stable. Only runningTasks (array) needs additional stabilization
+  // since filter()/spread creates new array references even for identical content.
+  const { worktreeIsRunning, worktreeRunningTasksRaw, worktreeMaxConcurrency } = useAppStore(
+    useShallow((state) => {
+      if (!worktreeKey) {
+        return {
+          worktreeIsRunning: false,
+          worktreeRunningTasksRaw: EMPTY_TASKS,
+          worktreeMaxConcurrency: undefined as number | undefined,
+        };
+      }
+      const wt = state.autoModeByWorktree[worktreeKey];
+      if (!wt) {
+        return {
+          worktreeIsRunning: false,
+          worktreeRunningTasksRaw: EMPTY_TASKS,
+          worktreeMaxConcurrency: undefined as number | undefined,
+        };
+      }
       return {
-        isRunning: false,
-        runningTasks: [],
-        branchName: null,
-        maxConcurrency: DEFAULT_MAX_CONCURRENCY,
+        worktreeIsRunning: wt.isRunning,
+        worktreeRunningTasksRaw: wt.runningTasks,
+        worktreeMaxConcurrency: wt.maxConcurrency,
       };
-    const key = getWorktreeKey(projectId, branchName);
-    return (
-      autoModeByWorktree[key] || {
-        isRunning: false,
-        runningTasks: [],
-        branchName,
-        maxConcurrency: DEFAULT_MAX_CONCURRENCY,
-      }
-    );
-  }, [autoModeByWorktree, projectId, branchName, getWorktreeKey]);
-
-  const isAutoModeRunning = worktreeAutoModeState.isRunning;
-  const runningAutoTasks = worktreeAutoModeState.runningTasks;
-  // Use the subscribed worktreeAutoModeState.maxConcurrency (from the reactive
-  // autoModeByWorktree store slice) so canStartNewTask stays reactive when
-  // refreshStatus updates worktree state or when the global setting changes.
-  // Falls back to the subscribed globalMaxConcurrency (also reactive) when no
-  // per-worktree value is set, and to DEFAULT_MAX_CONCURRENCY when no project.
+    })
+  );
+  // Stabilize runningTasks: useShallow uses Object.is per property, but
+  // runningTasks gets a new array ref after removeRunningTask/addRunningTask.
+  // Cache the previous value and only update when content actually changes.
+  const prevTasksRef = useRef<string[]>(EMPTY_TASKS);
+  const worktreeRunningTasks = useMemo(() => {
+    if (worktreeRunningTasksRaw === prevTasksRef.current) return prevTasksRef.current;
+    if (arraysEqual(prevTasksRef.current, worktreeRunningTasksRaw)) return prevTasksRef.current;
+    prevTasksRef.current = worktreeRunningTasksRaw;
+    return worktreeRunningTasksRaw;
+  }, [worktreeRunningTasksRaw]);
+
+  const isAutoModeRunning = worktreeIsRunning;
+  const runningAutoTasks = worktreeRunningTasks;
+  // Use worktreeMaxConcurrency (from the reactive per-key selector) so
+  // canStartNewTask stays reactive when refreshStatus updates worktree state
+  // or when the global setting changes.
   const maxConcurrency = projectId
-    ? (worktreeAutoModeState.maxConcurrency ?? globalMaxConcurrency)
+    ? (worktreeMaxConcurrency ?? globalMaxConcurrency)
     : DEFAULT_MAX_CONCURRENCY;
 
   // Check if we can start a new task based on concurrency limit
   const canStartNewTask = runningAutoTasks.length < maxConcurrency;
 
+  // Batch addAutoModeActivity calls to reduce Zustand set() frequency.
+  // Without batching, each WS event (especially auto_mode_progress which fires
+  // rapidly during streaming) triggers a separate set() → all subscriber selectors
+  // re-evaluate → on mobile this overwhelms React's batching → crash.
+  // This batches activities in a ref and flushes them in a single set() call.
+  const pendingActivitiesRef = useRef<Parameters<typeof addAutoModeActivity>[0][]>([]);
+  const flushTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+  const batchedAddAutoModeActivity = useCallback(
+    (activity: Parameters<typeof addAutoModeActivity>[0]) => {
+      pendingActivitiesRef.current.push(activity);
+      if (!flushTimerRef.current) {
+        flushTimerRef.current = setTimeout(() => {
+          const batch = pendingActivitiesRef.current;
+          pendingActivitiesRef.current = [];
+          flushTimerRef.current = null;
+          // Flush all pending activities in a single store update
+          for (const act of batch) {
+            addAutoModeActivity(act);
+          }
+        }, 100);
+      }
+    },
+    [addAutoModeActivity]
+  );
+
+  // Cleanup flush timer on unmount
+  useEffect(() => {
+    return () => {
+      if (flushTimerRef.current) {
+        clearTimeout(flushTimerRef.current);
+      }
+    };
+  }, []);
+
   // Ref to prevent refreshStatus and WebSocket handlers from overwriting optimistic state
   // during start/stop transitions.
   const isTransitioningRef = useRef(false);
@@ -498,7 +571,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
         case 'auto_mode_feature_start':
           if (event.featureId) {
             addRunningTask(eventProjectId, eventBranchName, event.featureId);
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'start',
               message: `Started working on feature`,
@@ -514,7 +587,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
             // briefly appear in backlog due to stale cache data
             addRecentlyCompletedFeature(event.featureId);
             removeRunningTask(eventProjectId, eventBranchName, event.featureId);
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'complete',
               message: event.passes
@@ -551,7 +624,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
               ? `Authentication failed: Please check your API key in Settings or run 'claude login' in terminal to re-authenticate.`
               : event.error;
 
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'error',
               message: errorMessage,
@@ -568,7 +641,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
         case 'auto_mode_progress':
           // Log progress updates (throttle to avoid spam)
           if (event.featureId && event.content && event.content.length > 10) {
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'progress',
               message: event.content.substring(0, 200), // Limit message length
@@ -579,7 +652,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
         case 'auto_mode_tool':
           // Log tool usage
           if (event.featureId && event.tool) {
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'tool',
               message: `Using tool: ${event.tool}`,
@@ -592,7 +665,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
           // Log phase transitions (Planning, Action, Verification)
           if (event.featureId && event.phase && event.message) {
             logger.debug(`[AutoMode] Phase: ${event.phase} for ${event.featureId}`);
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: event.phase,
               message: event.message,
@@ -618,7 +691,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
           // Log when planning phase begins
           if (event.featureId && event.mode && event.message) {
             logger.debug(`[AutoMode] Planning started (${event.mode}) for ${event.featureId}`);
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'planning',
               message: event.message,
@@ -631,7 +704,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
           // Log when plan is approved by user
           if (event.featureId) {
             logger.debug(`[AutoMode] Plan approved for ${event.featureId}`);
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'action',
               message: event.hasEdits
@@ -646,7 +719,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
           // Log when plan is auto-approved (requirePlanApproval=false)
           if (event.featureId) {
             logger.debug(`[AutoMode] Plan auto-approved for ${event.featureId}`);
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'action',
               message: 'Plan auto-approved, starting implementation...',
@@ -665,7 +738,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
             logger.debug(
               `[AutoMode] Plan revision requested for ${event.featureId} (v${revisionEvent.planVersion})`
             );
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'planning',
               message: `Revising plan based on feedback (v${revisionEvent.planVersion})...`,
@@ -681,7 +754,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
             logger.debug(
               `[AutoMode] Task ${taskEvent.taskId} started for ${event.featureId}: ${taskEvent.taskDescription}`
             );
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'progress',
               message: `▶ Starting ${taskEvent.taskId}: ${taskEvent.taskDescription}`,
@@ -696,7 +769,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
             logger.debug(
               `[AutoMode] Task ${taskEvent.taskId} completed for ${event.featureId} (${taskEvent.tasksCompleted}/${taskEvent.tasksTotal})`
             );
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'progress',
               message: `✓ ${taskEvent.taskId} done (${taskEvent.tasksCompleted}/${taskEvent.tasksTotal})`,
@@ -714,7 +787,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
             logger.debug(
               `[AutoMode] Phase ${phaseEvent.phaseNumber} completed for ${event.featureId}`
             );
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'action',
               message: `Phase ${phaseEvent.phaseNumber} completed`,
@@ -742,7 +815,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
             logger.debug(
               `[AutoMode] Summary saved for ${event.featureId}: ${summaryEvent.summary.substring(0, 100)}...`
             );
-            addAutoModeActivity({
+            batchedAddAutoModeActivity({
               featureId: event.featureId,
               type: 'progress',
               message: `Summary: ${summaryEvent.summary.substring(0, 100)}...`,
@@ -758,7 +831,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
     branchName,
     addRunningTask,
     removeRunningTask,
-    addAutoModeActivity,
+    batchedAddAutoModeActivity,
     getProjectIdFromPath,
     setPendingPlanApproval,
     setAutoModeRunning,
@@ -977,7 +1050,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
           removeRunningTask(currentProject.id, branchName, featureId);
 
           logger.info('Feature stopped successfully:', featureId);
-          addAutoModeActivity({
+          batchedAddAutoModeActivity({
             featureId,
             type: 'complete',
             message: 'Feature stopped by user',
@@ -993,7 +1066,7 @@ export function useAutoMode(worktree?: WorktreeInfo) {
         throw error;
       }
     },
-    [currentProject, branchName, removeRunningTask, addAutoModeActivity]
+    [currentProject, branchName, removeRunningTask, batchedAddAutoModeActivity]
   );
 
   return {
diff --git a/apps/ui/src/hooks/use-query-invalidation.ts b/apps/ui/src/hooks/use-query-invalidation.ts
index 241538e3d..2876d7cc0 100644
--- a/apps/ui/src/hooks/use-query-invalidation.ts
+++ b/apps/ui/src/hooks/use-query-invalidation.ts
@@ -13,6 +13,7 @@ import type { AutoModeEvent, SpecRegenerationEvent, StreamEvent } from '@/types/
 import type { IssueValidationEvent } from '@automaker/types';
 import { debounce, type DebouncedFunction } from '@automaker/utils/debounce';
 import { useEventRecencyStore } from './use-event-recency';
+import { isAnyFeatureTransitioning } from '@/lib/feature-transition-state';
 
 /**
  * Debounce configuration for auto_mode_progress invalidations
@@ -31,8 +32,10 @@ const FEATURE_LIST_INVALIDATION_EVENTS: AutoModeEvent['type'][] = [
   'auto_mode_feature_start',
   'auto_mode_feature_complete',
   'auto_mode_error',
-  'auto_mode_started',
-  'auto_mode_stopped',
+  // NOTE: auto_mode_started and auto_mode_stopped are intentionally excluded.
+  // These events signal auto-loop state changes, NOT feature data changes.
+  // Including them caused unnecessary refetches that raced with optimistic
+  // updates during start/stop cycles, triggering React error #185 on mobile.
   'plan_approval_required',
   'plan_approved',
   'plan_rejected',
@@ -176,8 +179,12 @@ export function useAutoModeQueryInvalidation(projectPath: string | undefined) {
       // This allows polling to be disabled when WebSocket events are flowing
       recordGlobalEvent();
 
-      // Invalidate feature list for lifecycle events
-      if (FEATURE_LIST_INVALIDATION_EVENTS.includes(event.type)) {
+      // Invalidate feature list for lifecycle events.
+      // Skip invalidation when a feature is mid-transition (e.g., being cancelled)
+      // because persistFeatureUpdate already handles the optimistic cache update.
+      // Without this guard, auto_mode_error / auto_mode_stopped WS events race
+      // with the optimistic update and cause re-render cascades on mobile (React #185).
+      if (FEATURE_LIST_INVALIDATION_EVENTS.includes(event.type) && !isAnyFeatureTransitioning()) {
         queryClient.invalidateQueries({
           queryKey: queryKeys.features.all(currentProjectPath),
         });
diff --git a/apps/ui/src/lib/feature-transition-state.ts b/apps/ui/src/lib/feature-transition-state.ts
new file mode 100644
index 000000000..ac72aed1a
--- /dev/null
+++ b/apps/ui/src/lib/feature-transition-state.ts
@@ -0,0 +1,19 @@
+/**
+ * Lightweight module-level state tracking which features are mid-transition
+ * (e.g., being cancelled). Used by useAutoModeQueryInvalidation to skip
+ * redundant cache invalidations while persistFeatureUpdate is in flight.
+ */
+
+const transitioningFeatures = new Set<string>();
+
+export function markFeatureTransitioning(featureId: string): void {
+  transitioningFeatures.add(featureId);
+}
+
+export function unmarkFeatureTransitioning(featureId: string): void {
+  transitioningFeatures.delete(featureId);
+}
+
+export function isAnyFeatureTransitioning(): boolean {
+  return transitioningFeatures.size > 0;
+}
diff --git a/apps/ui/src/store/app-store.ts b/apps/ui/src/store/app-store.ts
index 6bf808ed0..8e4918d19 100644
--- a/apps/ui/src/store/app-store.ts
+++ b/apps/ui/src/store/app-store.ts
@@ -1044,6 +1044,9 @@ export const useAppStore = create<AppState & AppActions>()((set, get) => ({
     set((state) => {
       const current = state.autoModeByWorktree[key];
       if (!current) return state;
+      // Idempotent: skip if task is not in the list to avoid creating new
+      // object references that trigger unnecessary re-renders.
+      if (!current.runningTasks.includes(taskId)) return state;
       return {
         autoModeByWorktree: {
           ...state.autoModeByWorktree,
@@ -1097,13 +1100,20 @@ export const useAppStore = create<AppState & AppActions>()((set, get) => ({
 
   addRecentlyCompletedFeature: (featureId: string) => {
     set((state) => {
+      // Idempotent: skip if already tracked to avoid creating a new Set reference
+      // that triggers unnecessary re-renders in useBoardColumnFeatures.
+      if (state.recentlyCompletedFeatures.has(featureId)) return state;
       const newSet = new Set(state.recentlyCompletedFeatures);
       newSet.add(featureId);
       return { recentlyCompletedFeatures: newSet };
     });
   },
 
-  clearRecentlyCompletedFeatures: () => set({ recentlyCompletedFeatures: new Set() }),
+  clearRecentlyCompletedFeatures: () => {
+    // Idempotent: skip if already empty to avoid creating a new Set reference.
+    if (get().recentlyCompletedFeatures.size === 0) return;
+    set({ recentlyCompletedFeatures: new Set() });
+  },
 
   setMaxConcurrency: (max) => set({ maxConcurrency: max }),