diff --git a/apps/ui/package.json b/apps/ui/package.json
index b28ad8c7..200df952 100644
--- a/apps/ui/package.json
+++ b/apps/ui/package.json
@@ -63,7 +63,8 @@
     "@radix-ui/react-switch": "1.2.6",
     "@radix-ui/react-tabs": "1.1.13",
     "@radix-ui/react-tooltip": "1.2.8",
-    "@tanstack/react-query": "5.90.12",
+    "@tanstack/react-query": "^5.90.17",
+    "@tanstack/react-query-devtools": "^5.91.2",
     "@tanstack/react-router": "1.141.6",
     "@uiw/react-codemirror": "4.25.4",
     "@xterm/addon-fit": "0.10.0",
diff --git a/apps/ui/src/lib/query-client.ts b/apps/ui/src/lib/query-client.ts
new file mode 100644
index 00000000..82344f2a
--- /dev/null
+++ b/apps/ui/src/lib/query-client.ts
@@ -0,0 +1,138 @@
+/**
+ * React Query Client Configuration
+ *
+ * Central configuration for TanStack React Query.
+ * Provides default options for queries and mutations including
+ * caching, retries, and error handling.
+ */
+
+import { QueryClient } from '@tanstack/react-query';
+import { toast } from 'sonner';
+import { createLogger } from '@automaker/utils/logger';
+import { isConnectionError, handleServerOffline } from './http-api-client';
+
+const logger = createLogger('QueryClient');
+
+/**
+ * Default stale times for different data types
+ */
+export const STALE_TIMES = {
+  /** Features change frequently during auto-mode */
+  FEATURES: 60 * 1000, // 1 minute
+  /** GitHub data is relatively stable */
+  GITHUB: 2 * 60 * 1000, // 2 minutes
+  /** Running agents state changes very frequently */
+  RUNNING_AGENTS: 5 * 1000, // 5 seconds
+  /** Agent output changes during streaming */
+  AGENT_OUTPUT: 5 * 1000, // 5 seconds
+  /** Usage data with polling */
+  USAGE: 30 * 1000, // 30 seconds
+  /** Models rarely change */
+  MODELS: 5 * 60 * 1000, // 5 minutes
+  /** CLI status rarely changes */
+  CLI_STATUS: 5 * 60 * 1000, // 5 minutes
+  /** Settings are relatively stable */
+  SETTINGS: 2 * 60 * 1000, // 2 minutes
+  /** Worktrees change during feature development */
+  WORKTREES: 30 * 1000, // 30 seconds
+  /** Sessions rarely change */
+  SESSIONS: 2 * 60 * 1000, // 2 minutes
+  /** Default for unspecified queries */
+  DEFAULT: 30 * 1000, // 30 seconds
+} as const;
+
+/**
+ * Default garbage collection times (gcTime, formerly cacheTime)
+ */
+export const GC_TIMES = {
+  /** Default garbage collection time */
+  DEFAULT: 5 * 60 * 1000, // 5 minutes
+  /** Extended for expensive queries */
+  EXTENDED: 10 * 60 * 1000, // 10 minutes
+} as const;
+
+/**
+ * Global error handler for queries
+ */
+const handleQueryError = (error: Error) => {
+  logger.error('Query error:', error);
+
+  // Check for connection errors (server offline)
+  if (isConnectionError(error)) {
+    handleServerOffline();
+    return;
+  }
+
+  // Don't toast for auth errors - those are handled by http-api-client
+  if (error.message === 'Unauthorized') {
+    return;
+  }
+};
+
+/**
+ * Global error handler for mutations
+ */
+const handleMutationError = (error: Error) => {
+  logger.error('Mutation error:', error);
+
+  // Check for connection errors
+  if (isConnectionError(error)) {
+    handleServerOffline();
+    return;
+  }
+
+  // Don't toast for auth errors
+  if (error.message === 'Unauthorized') {
+    return;
+  }
+
+  // Show error toast for other errors
+  toast.error('Operation failed', {
+    description: error.message || 'An unexpected error occurred',
+  });
+};
+
+/**
+ * Create and configure the QueryClient singleton
+ */
+export const queryClient = new QueryClient({
+  defaultOptions: {
+    queries: {
+      staleTime: STALE_TIMES.DEFAULT,
+      gcTime: GC_TIMES.DEFAULT,
+      retry: (failureCount, error) => {
+        // Don't retry on auth errors
+        if (error instanceof Error && error.message === 'Unauthorized') {
+          return false;
+        }
+        // Don't retry on connection errors (server offline)
+        if (isConnectionError(error)) {
+          return false;
+        }
+        // Retry up to 2 times for other errors
+        return failureCount < 2;
+      },
+      refetchOnWindowFocus: true,
+      refetchOnReconnect: true,
+      // Don't refetch on mount if data is fresh
+      refetchOnMount: true,
+    },
+    mutations: {
+      onError: handleMutationError,
+      retry: false, // Don't auto-retry mutations
+    },
+  },
+});
+
+/**
+ * Set up global query error handling
+ * This catches errors that aren't handled by individual queries
+ */
+queryClient.getQueryCache().subscribe((event) => {
+  if (event.type === 'updated' && event.query.state.status === 'error') {
+    const error = event.query.state.error;
+    if (error instanceof Error) {
+      handleQueryError(error);
+    }
+  }
+});
diff --git a/apps/ui/src/lib/query-keys.ts b/apps/ui/src/lib/query-keys.ts
new file mode 100644
index 00000000..b0eb7291
--- /dev/null
+++ b/apps/ui/src/lib/query-keys.ts
@@ -0,0 +1,280 @@
+/**
+ * Query Keys Factory
+ *
+ * Centralized query key definitions for React Query.
+ * Following the factory pattern for type-safe, consistent query keys.
+ *
+ * @see https://tkdodo.eu/blog/effective-react-query-keys
+ */
+
+/**
+ * Query keys for all API endpoints
+ *
+ * Structure follows the pattern:
+ * - ['entity'] for listing/global
+ * - ['entity', id] for single item
+ * - ['entity', id, 'sub-resource'] for nested resources
+ */
+export const queryKeys = {
+  // ============================================
+  // Features
+  // ============================================
+  features: {
+    /** All features for a project */
+    all: (projectPath: string) => ['features', projectPath] as const,
+    /** Single feature */
+    single: (projectPath: string, featureId: string) =>
+      ['features', projectPath, featureId] as const,
+    /** Agent output for a feature */
+    agentOutput: (projectPath: string, featureId: string) =>
+      ['features', projectPath, featureId, 'output'] as const,
+  },
+
+  // ============================================
+  // Worktrees
+  // ============================================
+  worktrees: {
+    /** All worktrees for a project */
+    all: (projectPath: string) => ['worktrees', projectPath] as const,
+    /** Single worktree info */
+    single: (projectPath: string, featureId: string) =>
+      ['worktrees', projectPath, featureId] as const,
+    /** Branches for a worktree */
+    branches: (worktreePath: string) => ['worktrees', 'branches', worktreePath] as const,
+    /** Worktree status */
+    status: (projectPath: string, featureId: string) =>
+      ['worktrees', projectPath, featureId, 'status'] as const,
+    /** Worktree diffs */
+    diffs: (projectPath: string, featureId: string) =>
+      ['worktrees', projectPath, featureId, 'diffs'] as const,
+    /** Init script for a project */
+    initScript: (projectPath: string) => ['worktrees', projectPath, 'init-script'] as const,
+    /** Available editors */
+    editors: () => ['worktrees', 'editors'] as const,
+  },
+
+  // ============================================
+  // GitHub
+  // ============================================
+  github: {
+    /** GitHub issues for a project */
+    issues: (projectPath: string) => ['github', 'issues', projectPath] as const,
+    /** GitHub PRs for a project */
+    prs: (projectPath: string) => ['github', 'prs', projectPath] as const,
+    /** GitHub validations for a project */
+    validations: (projectPath: string) => ['github', 'validations', projectPath] as const,
+    /** Single validation */
+    validation: (projectPath: string, issueNumber: number) =>
+      ['github', 'validations', projectPath, issueNumber] as const,
+    /** Issue comments */
+    issueComments: (projectPath: string, issueNumber: number) =>
+      ['github', 'issues', projectPath, issueNumber, 'comments'] as const,
+    /** Remote info */
+    remote: (projectPath: string) => ['github', 'remote', projectPath] as const,
+  },
+
+  // ============================================
+  // Settings
+  // ============================================
+  settings: {
+    /** Global settings */
+    global: () => ['settings', 'global'] as const,
+    /** Project-specific settings */
+    project: (projectPath: string) => ['settings', 'project', projectPath] as const,
+    /** Settings status */
+    status: () => ['settings', 'status'] as const,
+    /** Credentials (API keys) */
+    credentials: () => ['settings', 'credentials'] as const,
+    /** Discovered agents */
+    agents: (projectPath: string) => ['settings', 'agents', projectPath] as const,
+  },
+
+  // ============================================
+  // Usage & Billing
+  // ============================================
+  usage: {
+    /** Claude API usage */
+    claude: () => ['usage', 'claude'] as const,
+    /** Codex API usage */
+    codex: () => ['usage', 'codex'] as const,
+  },
+
+  // ============================================
+  // Models
+  // ============================================
+  models: {
+    /** Available models */
+    available: () => ['models', 'available'] as const,
+    /** Codex models */
+    codex: () => ['models', 'codex'] as const,
+    /** OpenCode models */
+    opencode: () => ['models', 'opencode'] as const,
+    /** OpenCode providers */
+    opencodeProviders: () => ['models', 'opencode', 'providers'] as const,
+    /** Provider status */
+    providers: () => ['models', 'providers'] as const,
+  },
+
+  // ============================================
+  // Sessions
+  // ============================================
+  sessions: {
+    /** All sessions */
+    all: (includeArchived?: boolean) => ['sessions', { includeArchived }] as const,
+    /** Session history */
+    history: (sessionId: string) => ['sessions', sessionId, 'history'] as const,
+    /** Session queue */
+    queue: (sessionId: string) => ['sessions', sessionId, 'queue'] as const,
+  },
+
+  // ============================================
+  // Running Agents
+  // ============================================
+  runningAgents: {
+    /** All running agents */
+    all: () => ['runningAgents'] as const,
+  },
+
+  // ============================================
+  // Auto Mode
+  // ============================================
+  autoMode: {
+    /** Auto mode status */
+    status: (projectPath?: string) => ['autoMode', 'status', projectPath] as const,
+    /** Context exists check */
+    contextExists: (projectPath: string, featureId: string) =>
+      ['autoMode', projectPath, featureId, 'context'] as const,
+  },
+
+  // ============================================
+  // Ideation
+  // ============================================
+  ideation: {
+    /** Ideation prompts */
+    prompts: () => ['ideation', 'prompts'] as const,
+    /** Ideas for a project */
+    ideas: (projectPath: string) => ['ideation', 'ideas', projectPath] as const,
+    /** Single idea */
+    idea: (projectPath: string, ideaId: string) =>
+      ['ideation', 'ideas', projectPath, ideaId] as const,
+    /** Session */
+    session: (projectPath: string, sessionId: string) =>
+      ['ideation', 'session', projectPath, sessionId] as const,
+  },
+
+  // ============================================
+  // CLI Status
+  // ============================================
+  cli: {
+    /** Claude CLI status */
+    claude: () => ['cli', 'claude'] as const,
+    /** Cursor CLI status */
+    cursor: () => ['cli', 'cursor'] as const,
+    /** Codex CLI status */
+    codex: () => ['cli', 'codex'] as const,
+    /** OpenCode CLI status */
+    opencode: () => ['cli', 'opencode'] as const,
+    /** GitHub CLI status */
+    github: () => ['cli', 'github'] as const,
+    /** API keys status */
+    apiKeys: () => ['cli', 'apiKeys'] as const,
+    /** Platform info */
+    platform: () => ['cli', 'platform'] as const,
+  },
+
+  // ============================================
+  // Cursor Permissions
+  // ============================================
+  cursorPermissions: {
+    /** Cursor permissions for a project */
+    permissions: (projectPath?: string) => ['cursorPermissions', projectPath] as const,
+  },
+
+  // ============================================
+  // Workspace
+  // ============================================
+  workspace: {
+    /** Workspace config */
+    config: () => ['workspace', 'config'] as const,
+    /** Workspace directories */
+    directories: () => ['workspace', 'directories'] as const,
+  },
+
+  // ============================================
+  // MCP (Model Context Protocol)
+  // ============================================
+  mcp: {
+    /** MCP server tools */
+    tools: (serverId: string) => ['mcp', 'tools', serverId] as const,
+  },
+
+  // ============================================
+  // Pipeline
+  // ============================================
+  pipeline: {
+    /** Pipeline config for a project */
+    config: (projectPath: string) => ['pipeline', projectPath] as const,
+  },
+
+  // ============================================
+  // Suggestions
+  // ============================================
+  suggestions: {
+    /** Suggestions status */
+    status: () => ['suggestions', 'status'] as const,
+  },
+
+  // ============================================
+  // Spec Regeneration
+  // ============================================
+  specRegeneration: {
+    /** Spec regeneration status */
+    status: (projectPath?: string) => ['specRegeneration', 'status', projectPath] as const,
+  },
+
+  // ============================================
+  // Spec
+  // ============================================
+  spec: {
+    /** Spec file content */
+    file: (projectPath: string) => ['spec', 'file', projectPath] as const,
+  },
+
+  // ============================================
+  // Context
+  // ============================================
+  context: {
+    /** File description */
+    file: (filePath: string) => ['context', 'file', filePath] as const,
+    /** Image description */
+    image: (imagePath: string) => ['context', 'image', imagePath] as const,
+  },
+
+  // ============================================
+  // File System
+  // ============================================
+  fs: {
+    /** Directory listing */
+    readdir: (dirPath: string) => ['fs', 'readdir', dirPath] as const,
+    /** File existence */
+    exists: (filePath: string) => ['fs', 'exists', filePath] as const,
+    /** File stats */
+    stat: (filePath: string) => ['fs', 'stat', filePath] as const,
+  },
+
+  // ============================================
+  // Git
+  // ============================================
+  git: {
+    /** Git diffs for a project */
+    diffs: (projectPath: string) => ['git', 'diffs', projectPath] as const,
+    /** File diff */
+    fileDiff: (projectPath: string, filePath: string) =>
+      ['git', 'diffs', projectPath, filePath] as const,
+  },
+} as const;
+
+/**
+ * Type helper to extract query key types
+ */
+export type QueryKeys = typeof queryKeys;
diff --git a/apps/ui/src/routes/__root.tsx b/apps/ui/src/routes/__root.tsx
index 9472545b..a139dbe9 100644
--- a/apps/ui/src/routes/__root.tsx
+++ b/apps/ui/src/routes/__root.tsx
@@ -1,5 +1,7 @@
 import { createRootRoute, Outlet, useLocation, useNavigate } from '@tanstack/react-router';
 import { useEffect, useState, useCallback, useDeferredValue, useRef } from 'react';
+import { QueryClientProvider } from '@tanstack/react-query';
+import { ReactQueryDevtools } from '@tanstack/react-query-devtools';
 import { createLogger } from '@automaker/utils/logger';
 import { Sidebar } from '@/components/layout/sidebar';
 import { ProjectSwitcher } from '@/components/layout/project-switcher';
@@ -27,6 +29,7 @@ import {
   signalMigrationComplete,
   performSettingsMigration,
 } from '@/hooks/use-settings-migration';
+import { queryClient } from '@/lib/query-client';
 import { Toaster } from 'sonner';
 import { Menu } from 'lucide-react';
 import { ThemeOption, themeOptions } from '@/config/theme-options';
@@ -856,9 +859,12 @@ function RootLayoutContent() {
 
 function RootLayout() {
   return (
-    <FileBrowserProvider>
-      <RootLayoutContent />
-    </FileBrowserProvider>
+    <QueryClientProvider client={queryClient}>
+      <FileBrowserProvider>
+        <RootLayoutContent />
+      </FileBrowserProvider>
+      <ReactQueryDevtools initialIsOpen={false} buttonPosition="bottom-left" />
+    </QueryClientProvider>
   );
 }
 
diff --git a/package-lock.json b/package-lock.json
index 00e0d253..41e0bfaf 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -29,7 +29,7 @@
     },
     "apps/server": {
       "name": "@automaker/server",
-      "version": "0.10.0",
+      "version": "0.11.0",
       "license": "SEE LICENSE IN LICENSE",
       "dependencies": {
         "@anthropic-ai/claude-agent-sdk": "0.1.76",
@@ -80,7 +80,7 @@
     },
     "apps/ui": {
       "name": "@automaker/ui",
-      "version": "0.10.0",
+      "version": "0.11.0",
       "hasInstallScript": true,
       "license": "SEE LICENSE IN LICENSE",
       "dependencies": {
@@ -108,7 +108,8 @@
         "@radix-ui/react-switch": "1.2.6",
         "@radix-ui/react-tabs": "1.1.13",
         "@radix-ui/react-tooltip": "1.2.8",
-        "@tanstack/react-query": "5.90.12",
+        "@tanstack/react-query": "^5.90.17",
+        "@tanstack/react-query-devtools": "^5.91.2",
         "@tanstack/react-router": "1.141.6",
         "@uiw/react-codemirror": "4.25.4",
         "@xterm/addon-fit": "0.10.0",
@@ -1483,7 +1484,7 @@
     },
     "node_modules/@electron/node-gyp": {
       "version": "10.2.0-electron.1",
-      "resolved": "git+https://github.com/electron/node-gyp.git#06b29aafb7708acef8b3669835c8a7857ebc92d2",
+      "resolved": "git+ssh://git@github.com/electron/node-gyp.git#06b29aafb7708acef8b3669835c8a7857ebc92d2",
       "integrity": "sha512-4MSBTT8y07YUDqf69/vSh80Hh791epYqGtWHO3zSKhYFwQg+gx9wi1PqbqP6YqC4WMsNxZ5l9oDmnWdK5pfCKQ==",
       "dev": true,
       "license": "MIT",
@@ -5788,9 +5789,19 @@
       }
     },
     "node_modules/@tanstack/query-core": {
-      "version": "5.90.12",
-      "resolved": "https://registry.npmjs.org/@tanstack/query-core/-/query-core-5.90.12.tgz",
-      "integrity": "sha512-T1/8t5DhV/SisWjDnaiU2drl6ySvsHj1bHBCWNXd+/T+Hh1cf6JodyEYMd5sgwm+b/mETT4EV3H+zCVczCU5hg==",
+      "version": "5.90.17",
+      "resolved": "https://registry.npmjs.org/@tanstack/query-core/-/query-core-5.90.17.tgz",
+      "integrity": "sha512-hDww+RyyYhjhUfoYQ4es6pbgxY7LNiPWxt4l1nJqhByjndxJ7HIjDxTBtfvMr5HwjYavMrd+ids5g4Rfev3lVQ==",
+      "license": "MIT",
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/tannerlinsley"
+      }
+    },
+    "node_modules/@tanstack/query-devtools": {
+      "version": "5.92.0",
+      "resolved": "https://registry.npmjs.org/@tanstack/query-devtools/-/query-devtools-5.92.0.tgz",
+      "integrity": "sha512-N8D27KH1vEpVacvZgJL27xC6yPFUy0Zkezn5gnB3L3gRCxlDeSuiya7fKge8Y91uMTnC8aSxBQhcK6ocY7alpQ==",
       "license": "MIT",
       "funding": {
         "type": "github",
@@ -5798,12 +5809,13 @@
       }
     },
     "node_modules/@tanstack/react-query": {
-      "version": "5.90.12",
-      "resolved": "https://registry.npmjs.org/@tanstack/react-query/-/react-query-5.90.12.tgz",
-      "integrity": "sha512-graRZspg7EoEaw0a8faiUASCyJrqjKPdqJ9EwuDRUF9mEYJ1YPczI9H+/agJ0mOJkPCJDk0lsz5QTrLZ/jQ2rg==",
+      "version": "5.90.17",
+      "resolved": "https://registry.npmjs.org/@tanstack/react-query/-/react-query-5.90.17.tgz",
+      "integrity": "sha512-PGc2u9KLwohDUSchjW9MZqeDQJfJDON7y4W7REdNBgiFKxQy+Pf7eGjiFWEj5xPqKzAeHYdAb62IWI1a9UJyGQ==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
-        "@tanstack/query-core": "5.90.12"
+        "@tanstack/query-core": "5.90.17"
       },
       "funding": {
         "type": "github",
@@ -5813,6 +5825,23 @@
         "react": "^18 || ^19"
       }
     },
+    "node_modules/@tanstack/react-query-devtools": {
+      "version": "5.91.2",
+      "resolved": "https://registry.npmjs.org/@tanstack/react-query-devtools/-/react-query-devtools-5.91.2.tgz",
+      "integrity": "sha512-ZJ1503ay5fFeEYFUdo7LMNFzZryi6B0Cacrgr2h1JRkvikK1khgIq6Nq2EcblqEdIlgB/r7XDW8f8DQ89RuUgg==",
+      "license": "MIT",
+      "dependencies": {
+        "@tanstack/query-devtools": "5.92.0"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/tannerlinsley"
+      },
+      "peerDependencies": {
+        "@tanstack/react-query": "^5.90.14",
+        "react": "^18 || ^19"
+      }
+    },
     "node_modules/@tanstack/react-router": {
       "version": "1.141.6",
       "resolved": "https://registry.npmjs.org/@tanstack/react-router/-/react-router-1.141.6.tgz",