diff --git a/apps/ui/src/components/dialogs/workspace-picker-modal.tsx b/apps/ui/src/components/dialogs/workspace-picker-modal.tsx
index 4f287465..5c144fd7 100644
--- a/apps/ui/src/components/dialogs/workspace-picker-modal.tsx
+++ b/apps/ui/src/components/dialogs/workspace-picker-modal.tsx
@@ -1,4 +1,3 @@
-import { useState, useEffect, useCallback } from 'react';
 import {
   Dialog,
   DialogContent,
@@ -9,7 +8,7 @@ import {
 } from '@/components/ui/dialog';
 import { Button } from '@/components/ui/button';
 import { Folder, Loader2, FolderOpen, AlertCircle } from 'lucide-react';
-import { getHttpApiClient } from '@/lib/http-api-client';
+import { useWorkspaceDirectories } from '@/hooks/queries';
 
 interface WorkspaceDirectory {
   name: string;
@@ -23,41 +22,15 @@ interface WorkspacePickerModalProps {
 }
 
 export function WorkspacePickerModal({ open, onOpenChange, onSelect }: WorkspacePickerModalProps) {
-  const [isLoading, setIsLoading] = useState(false);
-  const [directories, setDirectories] = useState<WorkspaceDirectory[]>([]);
-  const [error, setError] = useState<string | null>(null);
-
-  const loadDirectories = useCallback(async () => {
-    setIsLoading(true);
-    setError(null);
-
-    try {
-      const client = getHttpApiClient();
-      const result = await client.workspace.getDirectories();
-
-      if (result.success && result.directories) {
-        setDirectories(result.directories);
-      } else {
-        setError(result.error || 'Failed to load directories');
-      }
-    } catch (err) {
-      setError(err instanceof Error ? err.message : 'Failed to load directories');
-    } finally {
-      setIsLoading(false);
-    }
-  }, []);
-
-  // Load directories when modal opens
-  useEffect(() => {
-    if (open) {
-      loadDirectories();
-    }
-  }, [open, loadDirectories]);
+  // React Query hook - only fetch when modal is open
+  const { data: directories = [], isLoading, error, refetch } = useWorkspaceDirectories(open);
 
   const handleSelect = (dir: WorkspaceDirectory) => {
     onSelect(dir.path, dir.name);
   };
 
+  const errorMessage = error instanceof Error ? error.message : null;
+
   return (
     <Dialog open={open} onOpenChange={onOpenChange}>
       <DialogContent className="bg-card border-border max-w-lg max-h-[80vh] flex flex-col">
@@ -79,19 +52,19 @@ export function WorkspacePickerModal({ open, onOpenChange, onSelect }: Workspace
             </div>
           )}
 
-          {error && !isLoading && (
+          {errorMessage && !isLoading && (
             <div className="flex flex-col items-center justify-center h-full gap-3 text-center px-4">
               <div className="w-12 h-12 rounded-full bg-destructive/10 flex items-center justify-center">
                 <AlertCircle className="w-6 h-6 text-destructive" />
               </div>
-              <p className="text-sm text-destructive">{error}</p>
-              <Button variant="secondary" size="sm" onClick={loadDirectories} className="mt-2">
+              <p className="text-sm text-destructive">{errorMessage}</p>
+              <Button variant="secondary" size="sm" onClick={() => refetch()} className="mt-2">
                 Try Again
               </Button>
             </div>
           )}
 
-          {!isLoading && !error && directories.length === 0 && (
+          {!isLoading && !errorMessage && directories.length === 0 && (
             <div className="flex flex-col items-center justify-center h-full gap-3 text-center px-4">
               <div className="w-12 h-12 rounded-full bg-muted flex items-center justify-center">
                 <Folder className="w-6 h-6 text-muted-foreground" />
@@ -102,7 +75,7 @@ export function WorkspacePickerModal({ open, onOpenChange, onSelect }: Workspace
             </div>
           )}
 
-          {!isLoading && !error && directories.length > 0 && (
+          {!isLoading && !errorMessage && directories.length > 0 && (
             <div className="space-y-2">
               {directories.map((dir) => (
                 <button
diff --git a/apps/ui/src/components/session-manager.tsx b/apps/ui/src/components/session-manager.tsx
index 88c31acc..c4b7f119 100644
--- a/apps/ui/src/components/session-manager.tsx
+++ b/apps/ui/src/components/session-manager.tsx
@@ -1,5 +1,6 @@
-import { useState, useEffect } from 'react';
+import { useState, useEffect, useCallback } from 'react';
 import { createLogger } from '@automaker/utils/logger';
+import { useQueryClient } from '@tanstack/react-query';
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
 
 const logger = createLogger('SessionManager');
@@ -22,6 +23,8 @@ import { cn } from '@/lib/utils';
 import type { SessionListItem } from '@/types/electron';
 import { useKeyboardShortcutsConfig } from '@/hooks/use-keyboard-shortcuts';
 import { getElectronAPI } from '@/lib/electron';
+import { useSessions } from '@/hooks/queries';
+import { queryKeys } from '@/lib/query-keys';
 import { DeleteSessionDialog } from '@/components/dialogs/delete-session-dialog';
 import { DeleteAllArchivedSessionsDialog } from '@/components/dialogs/delete-all-archived-sessions-dialog';
 
@@ -102,7 +105,7 @@ export function SessionManager({
   onQuickCreateRef,
 }: SessionManagerProps) {
   const shortcuts = useKeyboardShortcutsConfig();
-  const [sessions, setSessions] = useState<SessionListItem[]>([]);
+  const queryClient = useQueryClient();
   const [activeTab, setActiveTab] = useState<'active' | 'archived'>('active');
   const [editingSessionId, setEditingSessionId] = useState<string | null>(null);
   const [editingName, setEditingName] = useState('');
@@ -113,8 +116,11 @@ export function SessionManager({
   const [sessionToDelete, setSessionToDelete] = useState<SessionListItem | null>(null);
   const [isDeleteAllArchivedDialogOpen, setIsDeleteAllArchivedDialogOpen] = useState(false);
 
+  // Use React Query for sessions list - always include archived, filter client-side
+  const { data: sessions = [], refetch: refetchSessions } = useSessions(true);
+
   // Check running state for all sessions
-  const checkRunningSessions = async (sessionList: SessionListItem[]) => {
+  const checkRunningSessions = useCallback(async (sessionList: SessionListItem[]) => {
     const api = getElectronAPI();
     if (!api?.agent) return;
 
@@ -134,26 +140,25 @@ export function SessionManager({
     }
 
     setRunningSessions(runningIds);
-  };
-
-  // Load sessions
-  const loadSessions = async () => {
-    const api = getElectronAPI();
-    if (!api?.sessions) return;
-
-    // Always load all sessions and filter client-side
-    const result = await api.sessions.list(true);
-    if (result.success && result.sessions) {
-      setSessions(result.sessions);
-      // Check running state for all sessions
-      await checkRunningSessions(result.sessions);
-    }
-  };
-
-  useEffect(() => {
-    loadSessions();
   }, []);
 
+  // Helper to invalidate sessions cache and refetch
+  const invalidateSessions = useCallback(async () => {
+    await queryClient.invalidateQueries({ queryKey: queryKeys.sessions.all(true) });
+    // Also check running state after invalidation
+    const result = await refetchSessions();
+    if (result.data) {
+      await checkRunningSessions(result.data);
+    }
+  }, [queryClient, refetchSessions, checkRunningSessions]);
+
+  // Check running state on initial load
+  useEffect(() => {
+    if (sessions.length > 0) {
+      checkRunningSessions(sessions);
+    }
+  }, [sessions.length > 0]); // Only run when sessions first load
+
   // Periodically check running state for sessions (useful for detecting when agents finish)
   useEffect(() => {
     // Only poll if there are running sessions
@@ -166,7 +171,7 @@ export function SessionManager({
     }, 3000); // Check every 3 seconds
 
     return () => clearInterval(interval);
-  }, [sessions, runningSessions.size, isCurrentSessionThinking]);
+  }, [sessions, runningSessions.size, isCurrentSessionThinking, checkRunningSessions]);
 
   // Create new session with random name
   const handleCreateSession = async () => {
@@ -180,7 +185,7 @@ export function SessionManager({
     if (result.success && result.session?.id) {
       setNewSessionName('');
       setIsCreating(false);
-      await loadSessions();
+      await invalidateSessions();
       onSelectSession(result.session.id);
     }
   };
@@ -195,7 +200,7 @@ export function SessionManager({
     const result = await api.sessions.create(sessionName, projectPath, projectPath);
 
     if (result.success && result.session?.id) {
-      await loadSessions();
+      await invalidateSessions();
       onSelectSession(result.session.id);
     }
   };
@@ -222,7 +227,7 @@ export function SessionManager({
     if (result.success) {
       setEditingSessionId(null);
       setEditingName('');
-      await loadSessions();
+      await invalidateSessions();
     }
   };
 
@@ -241,7 +246,7 @@ export function SessionManager({
         if (currentSessionId === sessionId) {
           onSelectSession(null);
         }
-        await loadSessions();
+        await invalidateSessions();
       } else {
         logger.error('[SessionManager] Archive failed:', result.error);
       }
@@ -261,7 +266,7 @@ export function SessionManager({
     try {
       const result = await api.sessions.unarchive(sessionId);
       if (result.success) {
-        await loadSessions();
+        await invalidateSessions();
       } else {
         logger.error('[SessionManager] Unarchive failed:', result.error);
       }
@@ -283,7 +288,7 @@ export function SessionManager({
 
     const result = await api.sessions.delete(sessionId);
     if (result.success) {
-      await loadSessions();
+      await invalidateSessions();
       if (currentSessionId === sessionId) {
         // Switch to another session or create a new one
         const activeSessionsList = sessions.filter((s) => !s.isArchived);
@@ -305,7 +310,7 @@ export function SessionManager({
       await api.sessions.delete(session.id);
     }
 
-    await loadSessions();
+    await invalidateSessions();
     setIsDeleteAllArchivedDialogOpen(false);
   };
 
diff --git a/apps/ui/src/components/ui/git-diff-panel.tsx b/apps/ui/src/components/ui/git-diff-panel.tsx
index 803ff46c..5ac14e5b 100644
--- a/apps/ui/src/components/ui/git-diff-panel.tsx
+++ b/apps/ui/src/components/ui/git-diff-panel.tsx
@@ -1,5 +1,4 @@
-import { useState, useEffect, useMemo, useCallback } from 'react';
-import { getElectronAPI } from '@/lib/electron';
+import { useState, useMemo } from 'react';
 import { cn } from '@/lib/utils';
 import {
   File,
@@ -15,6 +14,7 @@ import {
   AlertCircle,
 } from 'lucide-react';
 import { Button } from './button';
+import { useWorktreeDiffs, useGitDiffs } from '@/hooks/queries';
 import type { FileStatus } from '@/types/electron';
 
 interface GitDiffPanelProps {
@@ -350,56 +350,44 @@ export function GitDiffPanel({
   useWorktrees = false,
 }: GitDiffPanelProps) {
   const [isExpanded, setIsExpanded] = useState(!compact);
-  const [isLoading, setIsLoading] = useState(false);
-  const [error, setError] = useState<string | null>(null);
-  const [files, setFiles] = useState<FileStatus[]>([]);
-  const [diffContent, setDiffContent] = useState<string>('');
   const [expandedFiles, setExpandedFiles] = useState<Set<string>>(new Set());
 
-  const loadDiffs = useCallback(async () => {
-    setIsLoading(true);
-    setError(null);
-    try {
-      const api = getElectronAPI();
+  // Use worktree diffs hook when worktrees are enabled and panel is expanded
+  // Pass undefined for featureId when not using worktrees to disable the query
+  const {
+    data: worktreeDiffsData,
+    isLoading: isLoadingWorktree,
+    error: worktreeError,
+    refetch: refetchWorktree,
+  } = useWorktreeDiffs(
+    useWorktrees && isExpanded ? projectPath : undefined,
+    useWorktrees && isExpanded ? featureId : undefined
+  );
 
-      // Use worktree API if worktrees are enabled, otherwise use git API for main project
-      if (useWorktrees) {
-        if (!api?.worktree?.getDiffs) {
-          throw new Error('Worktree API not available');
-        }
-        const result = await api.worktree.getDiffs(projectPath, featureId);
-        if (result.success) {
-          setFiles(result.files || []);
-          setDiffContent(result.diff || '');
-        } else {
-          setError(result.error || 'Failed to load diffs');
-        }
-      } else {
-        // Use git API for main project diffs
-        if (!api?.git?.getDiffs) {
-          throw new Error('Git API not available');
-        }
-        const result = await api.git.getDiffs(projectPath);
-        if (result.success) {
-          setFiles(result.files || []);
-          setDiffContent(result.diff || '');
-        } else {
-          setError(result.error || 'Failed to load diffs');
-        }
-      }
-    } catch (err) {
-      setError(err instanceof Error ? err.message : 'Failed to load diffs');
-    } finally {
-      setIsLoading(false);
-    }
-  }, [projectPath, featureId, useWorktrees]);
+  // Use git diffs hook when worktrees are disabled and panel is expanded
+  const {
+    data: gitDiffsData,
+    isLoading: isLoadingGit,
+    error: gitError,
+    refetch: refetchGit,
+  } = useGitDiffs(projectPath, !useWorktrees && isExpanded);
 
-  // Load diffs when expanded
-  useEffect(() => {
-    if (isExpanded) {
-      loadDiffs();
-    }
-  }, [isExpanded, loadDiffs]);
+  // Select the appropriate data based on useWorktrees prop
+  const diffsData = useWorktrees ? worktreeDiffsData : gitDiffsData;
+  const isLoading = useWorktrees ? isLoadingWorktree : isLoadingGit;
+  const queryError = useWorktrees ? worktreeError : gitError;
+
+  // Extract files and diff content from the data
+  const files: FileStatus[] = diffsData?.files ?? [];
+  const diffContent = diffsData?.diff ?? '';
+  const error = queryError
+    ? queryError instanceof Error
+      ? queryError.message
+      : 'Failed to load diffs'
+    : null;
+
+  // Refetch function
+  const loadDiffs = useWorktrees ? refetchWorktree : refetchGit;
 
   const parsedDiffs = useMemo(() => parseDiff(diffContent), [diffContent]);
 
diff --git a/apps/ui/src/components/views/ideation-view/components/prompt-list.tsx b/apps/ui/src/components/views/ideation-view/components/prompt-list.tsx
index d87600f3..fd806248 100644
--- a/apps/ui/src/components/views/ideation-view/components/prompt-list.tsx
+++ b/apps/ui/src/components/views/ideation-view/components/prompt-list.tsx
@@ -8,7 +8,7 @@ import { Card, CardContent } from '@/components/ui/card';
 import { useGuidedPrompts } from '@/hooks/use-guided-prompts';
 import { useIdeationStore } from '@/store/ideation-store';
 import { useAppStore } from '@/store/app-store';
-import { getElectronAPI } from '@/lib/electron';
+import { useGenerateIdeationSuggestions } from '@/hooks/mutations';
 import { toast } from 'sonner';
 import { useNavigate } from '@tanstack/react-router';
 import type { IdeaCategory, IdeationPrompt } from '@automaker/types';
@@ -27,6 +27,9 @@ export function PromptList({ category, onBack }: PromptListProps) {
   const [loadingPromptId, setLoadingPromptId] = useState<string | null>(null);
   const [startedPrompts, setStartedPrompts] = useState<Set<string>>(new Set());
   const navigate = useNavigate();
+
+  // React Query mutation
+  const generateMutation = useGenerateIdeationSuggestions(currentProject?.path ?? '');
   const {
     getPromptsByCategory,
     isLoading: isLoadingPrompts,
@@ -56,7 +59,7 @@ export function PromptList({ category, onBack }: PromptListProps) {
       return;
     }
 
-    if (loadingPromptId || generatingPromptIds.has(prompt.id)) return;
+    if (loadingPromptId || generateMutation.isPending || generatingPromptIds.has(prompt.id)) return;
 
     setLoadingPromptId(prompt.id);
 
@@ -68,42 +71,31 @@ export function PromptList({ category, onBack }: PromptListProps) {
     toast.info(`Generating ideas for "${prompt.title}"...`);
     setMode('dashboard');
 
-    try {
-      const api = getElectronAPI();
-      const result = await api.ideation?.generateSuggestions(
-        currentProject.path,
-        prompt.id,
-        category
-      );
-
-      if (result?.success && result.suggestions) {
-        updateJobStatus(jobId, 'ready', result.suggestions);
-        toast.success(`Generated ${result.suggestions.length} ideas for "${prompt.title}"`, {
-          duration: 10000,
-          action: {
-            label: 'View Ideas',
-            onClick: () => {
-              setMode('dashboard');
-              navigate({ to: '/ideation' });
+    generateMutation.mutate(
+      { promptId: prompt.id, category },
+      {
+        onSuccess: (data) => {
+          updateJobStatus(jobId, 'ready', data.suggestions);
+          toast.success(`Generated ${data.suggestions.length} ideas for "${prompt.title}"`, {
+            duration: 10000,
+            action: {
+              label: 'View Ideas',
+              onClick: () => {
+                setMode('dashboard');
+                navigate({ to: '/ideation' });
+              },
             },
-          },
-        });
-      } else {
-        updateJobStatus(
-          jobId,
-          'error',
-          undefined,
-          result?.error || 'Failed to generate suggestions'
-        );
-        toast.error(result?.error || 'Failed to generate suggestions');
+          });
+          setLoadingPromptId(null);
+        },
+        onError: (error) => {
+          console.error('Failed to generate suggestions:', error);
+          updateJobStatus(jobId, 'error', undefined, error.message);
+          toast.error(error.message);
+          setLoadingPromptId(null);
+        },
       }
-    } catch (error) {
-      console.error('Failed to generate suggestions:', error);
-      updateJobStatus(jobId, 'error', undefined, (error as Error).message);
-      toast.error((error as Error).message);
-    } finally {
-      setLoadingPromptId(null);
-    }
+    );
   };
 
   return (
diff --git a/apps/ui/src/components/views/spec-view/hooks/use-spec-generation.ts b/apps/ui/src/components/views/spec-view/hooks/use-spec-generation.ts
index 69054125..2b49cd6d 100644
--- a/apps/ui/src/components/views/spec-view/hooks/use-spec-generation.ts
+++ b/apps/ui/src/components/views/spec-view/hooks/use-spec-generation.ts
@@ -10,6 +10,7 @@ import { createElement } from 'react';
 import { SPEC_FILE_WRITE_DELAY, STATUS_CHECK_INTERVAL_MS } from '../constants';
 import type { FeatureCount } from '../types';
 import type { SpecRegenerationEvent } from '@/types/electron';
+import { useCreateSpec, useRegenerateSpec, useGenerateFeatures } from '@/hooks/mutations';
 
 interface UseSpecGenerationOptions {
   loadSpec: () => Promise<void>;
@@ -18,6 +19,11 @@ interface UseSpecGenerationOptions {
 export function useSpecGeneration({ loadSpec }: UseSpecGenerationOptions) {
   const { currentProject } = useAppStore();
 
+  // React Query mutations
+  const createSpecMutation = useCreateSpec(currentProject?.path ?? '');
+  const regenerateSpecMutation = useRegenerateSpec(currentProject?.path ?? '');
+  const generateFeaturesMutation = useGenerateFeatures(currentProject?.path ?? '');
+
   // Dialog visibility state
   const [showCreateDialog, setShowCreateDialog] = useState(false);
   const [showRegenerateDialog, setShowRegenerateDialog] = useState(false);
@@ -404,47 +410,34 @@ export function useSpecGeneration({ loadSpec }: UseSpecGenerationOptions) {
     logsRef.current = '';
     setLogs('');
     logger.debug('[useSpecGeneration] Starting spec creation, generateFeatures:', generateFeatures);
-    try {
-      const api = getElectronAPI();
-      if (!api.specRegeneration) {
-        logger.error('[useSpecGeneration] Spec regeneration not available');
-        setIsCreating(false);
-        return;
-      }
-      const result = await api.specRegeneration.create(
-        currentProject.path,
-        projectOverview.trim(),
-        generateFeatures,
-        analyzeProjectOnCreate,
-        generateFeatures ? featureCountOnCreate : undefined
-      );
 
-      if (!result.success) {
-        const errorMsg = result.error || 'Unknown error';
-        logger.error('[useSpecGeneration] Failed to start spec creation:', errorMsg);
-        setIsCreating(false);
-        setCurrentPhase('error');
-        setErrorMessage(errorMsg);
-        const errorLog = `[Error] Failed to start spec creation: ${errorMsg}\n`;
-        logsRef.current = errorLog;
-        setLogs(errorLog);
+    createSpecMutation.mutate(
+      {
+        projectOverview: projectOverview.trim(),
+        generateFeatures,
+        analyzeProject: analyzeProjectOnCreate,
+        featureCount: generateFeatures ? featureCountOnCreate : undefined,
+      },
+      {
+        onError: (error) => {
+          const errorMsg = error.message;
+          logger.error('[useSpecGeneration] Failed to create spec:', errorMsg);
+          setIsCreating(false);
+          setCurrentPhase('error');
+          setErrorMessage(errorMsg);
+          const errorLog = `[Error] Failed to create spec: ${errorMsg}\n`;
+          logsRef.current = errorLog;
+          setLogs(errorLog);
+        },
       }
-    } catch (error) {
-      const errorMsg = error instanceof Error ? error.message : String(error);
-      logger.error('[useSpecGeneration] Failed to create spec:', errorMsg);
-      setIsCreating(false);
-      setCurrentPhase('error');
-      setErrorMessage(errorMsg);
-      const errorLog = `[Error] Failed to create spec: ${errorMsg}\n`;
-      logsRef.current = errorLog;
-      setLogs(errorLog);
-    }
+    );
   }, [
     currentProject,
     projectOverview,
     generateFeatures,
     analyzeProjectOnCreate,
     featureCountOnCreate,
+    createSpecMutation,
   ]);
 
   const handleRegenerate = useCallback(async () => {
@@ -460,47 +453,34 @@ export function useSpecGeneration({ loadSpec }: UseSpecGenerationOptions) {
       '[useSpecGeneration] Starting spec regeneration, generateFeatures:',
       generateFeaturesOnRegenerate
     );
-    try {
-      const api = getElectronAPI();
-      if (!api.specRegeneration) {
-        logger.error('[useSpecGeneration] Spec regeneration not available');
-        setIsRegenerating(false);
-        return;
-      }
-      const result = await api.specRegeneration.generate(
-        currentProject.path,
-        projectDefinition.trim(),
-        generateFeaturesOnRegenerate,
-        analyzeProjectOnRegenerate,
-        generateFeaturesOnRegenerate ? featureCountOnRegenerate : undefined
-      );
 
-      if (!result.success) {
-        const errorMsg = result.error || 'Unknown error';
-        logger.error('[useSpecGeneration] Failed to start regeneration:', errorMsg);
-        setIsRegenerating(false);
-        setCurrentPhase('error');
-        setErrorMessage(errorMsg);
-        const errorLog = `[Error] Failed to start regeneration: ${errorMsg}\n`;
-        logsRef.current = errorLog;
-        setLogs(errorLog);
+    regenerateSpecMutation.mutate(
+      {
+        projectDefinition: projectDefinition.trim(),
+        generateFeatures: generateFeaturesOnRegenerate,
+        analyzeProject: analyzeProjectOnRegenerate,
+        featureCount: generateFeaturesOnRegenerate ? featureCountOnRegenerate : undefined,
+      },
+      {
+        onError: (error) => {
+          const errorMsg = error.message;
+          logger.error('[useSpecGeneration] Failed to regenerate spec:', errorMsg);
+          setIsRegenerating(false);
+          setCurrentPhase('error');
+          setErrorMessage(errorMsg);
+          const errorLog = `[Error] Failed to regenerate spec: ${errorMsg}\n`;
+          logsRef.current = errorLog;
+          setLogs(errorLog);
+        },
       }
-    } catch (error) {
-      const errorMsg = error instanceof Error ? error.message : String(error);
-      logger.error('[useSpecGeneration] Failed to regenerate spec:', errorMsg);
-      setIsRegenerating(false);
-      setCurrentPhase('error');
-      setErrorMessage(errorMsg);
-      const errorLog = `[Error] Failed to regenerate spec: ${errorMsg}\n`;
-      logsRef.current = errorLog;
-      setLogs(errorLog);
-    }
+    );
   }, [
     currentProject,
     projectDefinition,
     generateFeaturesOnRegenerate,
     analyzeProjectOnRegenerate,
     featureCountOnRegenerate,
+    regenerateSpecMutation,
   ]);
 
   const handleGenerateFeatures = useCallback(async () => {
@@ -513,36 +493,20 @@ export function useSpecGeneration({ loadSpec }: UseSpecGenerationOptions) {
     logsRef.current = '';
     setLogs('');
     logger.debug('[useSpecGeneration] Starting feature generation from existing spec');
-    try {
-      const api = getElectronAPI();
-      if (!api.specRegeneration) {
-        logger.error('[useSpecGeneration] Spec regeneration not available');
-        setIsGeneratingFeatures(false);
-        return;
-      }
-      const result = await api.specRegeneration.generateFeatures(currentProject.path);
 
-      if (!result.success) {
-        const errorMsg = result.error || 'Unknown error';
-        logger.error('[useSpecGeneration] Failed to start feature generation:', errorMsg);
+    generateFeaturesMutation.mutate(undefined, {
+      onError: (error) => {
+        const errorMsg = error.message;
+        logger.error('[useSpecGeneration] Failed to generate features:', errorMsg);
         setIsGeneratingFeatures(false);
         setCurrentPhase('error');
         setErrorMessage(errorMsg);
-        const errorLog = `[Error] Failed to start feature generation: ${errorMsg}\n`;
+        const errorLog = `[Error] Failed to generate features: ${errorMsg}\n`;
         logsRef.current = errorLog;
         setLogs(errorLog);
-      }
-    } catch (error) {
-      const errorMsg = error instanceof Error ? error.message : String(error);
-      logger.error('[useSpecGeneration] Failed to generate features:', errorMsg);
-      setIsGeneratingFeatures(false);
-      setCurrentPhase('error');
-      setErrorMessage(errorMsg);
-      const errorLog = `[Error] Failed to generate features: ${errorMsg}\n`;
-      logsRef.current = errorLog;
-      setLogs(errorLog);
-    }
-  }, [currentProject]);
+      },
+    });
+  }, [currentProject, generateFeaturesMutation]);
 
   return {
     // Dialog state
diff --git a/apps/ui/src/components/views/spec-view/hooks/use-spec-loading.ts b/apps/ui/src/components/views/spec-view/hooks/use-spec-loading.ts
index 4343e300..4186bb72 100644
--- a/apps/ui/src/components/views/spec-view/hooks/use-spec-loading.ts
+++ b/apps/ui/src/components/views/spec-view/hooks/use-spec-loading.ts
@@ -1,61 +1,53 @@
 import { useEffect, useState, useCallback } from 'react';
-import { createLogger } from '@automaker/utils/logger';
 import { useAppStore } from '@/store/app-store';
-
-const logger = createLogger('SpecLoading');
-import { getElectronAPI } from '@/lib/electron';
+import { useSpecFile, useSpecRegenerationStatus } from '@/hooks/queries';
+import { useQueryClient } from '@tanstack/react-query';
+import { queryKeys } from '@/lib/query-keys';
 
 export function useSpecLoading() {
   const { currentProject, setAppSpec } = useAppStore();
-  const [isLoading, setIsLoading] = useState(true);
+  const queryClient = useQueryClient();
   const [specExists, setSpecExists] = useState(true);
-  const [isGenerationRunning, setIsGenerationRunning] = useState(false);
 
-  const loadSpec = useCallback(async () => {
-    if (!currentProject) return;
+  // React Query hooks
+  const specFileQuery = useSpecFile(currentProject?.path);
+  const statusQuery = useSpecRegenerationStatus(currentProject?.path);
 
-    setIsLoading(true);
-    try {
-      const api = getElectronAPI();
-
-      // Check if spec generation is running before trying to load
-      // This prevents showing "No App Specification Found" during generation
-      if (api.specRegeneration) {
-        const status = await api.specRegeneration.status(currentProject.path);
-        if (status.success && status.isRunning) {
-          logger.debug('Spec generation is running for this project, skipping load');
-          setIsGenerationRunning(true);
-          setIsLoading(false);
-          return;
-        }
-      }
-      // Always reset when generation is not running (handles edge case where api.specRegeneration might not be available)
-      setIsGenerationRunning(false);
-
-      const result = await api.readFile(`${currentProject.path}/.automaker/app_spec.txt`);
-
-      if (result.success && result.content) {
-        setAppSpec(result.content);
-        setSpecExists(true);
-      } else {
-        // File doesn't exist
-        setAppSpec('');
-        setSpecExists(false);
-      }
-    } catch (error) {
-      logger.error('Failed to load spec:', error);
-      setSpecExists(false);
-    } finally {
-      setIsLoading(false);
-    }
-  }, [currentProject, setAppSpec]);
+  const isGenerationRunning = statusQuery.data?.isRunning ?? false;
 
+  // Update app store and specExists when spec file data changes
   useEffect(() => {
-    loadSpec();
-  }, [loadSpec]);
+    if (specFileQuery.data && !isGenerationRunning) {
+      setAppSpec(specFileQuery.data.content);
+      setSpecExists(specFileQuery.data.exists);
+    }
+  }, [specFileQuery.data, setAppSpec, isGenerationRunning]);
+
+  // Manual reload function (invalidates cache)
+  const loadSpec = useCallback(async () => {
+    if (!currentProject?.path) return;
+
+    // First check if generation is running
+    await queryClient.invalidateQueries({
+      queryKey: queryKeys.specRegeneration.status(currentProject.path),
+    });
+
+    const statusData = queryClient.getQueryData<{ isRunning: boolean }>(
+      queryKeys.specRegeneration.status(currentProject.path)
+    );
+
+    if (statusData?.isRunning) {
+      return;
+    }
+
+    // Invalidate and refetch spec file
+    await queryClient.invalidateQueries({
+      queryKey: queryKeys.spec.file(currentProject.path),
+    });
+  }, [currentProject?.path, queryClient]);
 
   return {
-    isLoading,
+    isLoading: specFileQuery.isLoading,
     specExists,
     setSpecExists,
     isGenerationRunning,
diff --git a/apps/ui/src/components/views/spec-view/hooks/use-spec-save.ts b/apps/ui/src/components/views/spec-view/hooks/use-spec-save.ts
index 5b0bbb47..03812fd3 100644
--- a/apps/ui/src/components/views/spec-view/hooks/use-spec-save.ts
+++ b/apps/ui/src/components/views/spec-view/hooks/use-spec-save.ts
@@ -1,28 +1,20 @@
 import { useState } from 'react';
-import { createLogger } from '@automaker/utils/logger';
 import { useAppStore } from '@/store/app-store';
-
-const logger = createLogger('SpecSave');
-import { getElectronAPI } from '@/lib/electron';
+import { useSaveSpec } from '@/hooks/mutations';
 
 export function useSpecSave() {
   const { currentProject, appSpec, setAppSpec } = useAppStore();
-  const [isSaving, setIsSaving] = useState(false);
   const [hasChanges, setHasChanges] = useState(false);
 
+  // React Query mutation
+  const saveMutation = useSaveSpec(currentProject?.path ?? '');
+
   const saveSpec = async () => {
     if (!currentProject) return;
 
-    setIsSaving(true);
-    try {
-      const api = getElectronAPI();
-      await api.writeFile(`${currentProject.path}/.automaker/app_spec.txt`, appSpec);
-      setHasChanges(false);
-    } catch (error) {
-      logger.error('Failed to save spec:', error);
-    } finally {
-      setIsSaving(false);
-    }
+    saveMutation.mutate(appSpec, {
+      onSuccess: () => setHasChanges(false),
+    });
   };
 
   const handleChange = (value: string) => {
@@ -31,7 +23,7 @@ export function useSpecSave() {
   };
 
   return {
-    isSaving,
+    isSaving: saveMutation.isPending,
     hasChanges,
     setHasChanges,
     saveSpec,
diff --git a/apps/ui/src/hooks/use-board-background-settings.ts b/apps/ui/src/hooks/use-board-background-settings.ts
index fdb09b36..33618941 100644
--- a/apps/ui/src/hooks/use-board-background-settings.ts
+++ b/apps/ui/src/hooks/use-board-background-settings.ts
@@ -1,36 +1,26 @@
 import { useCallback } from 'react';
-import { createLogger } from '@automaker/utils/logger';
 import { useAppStore } from '@/store/app-store';
-import { getHttpApiClient } from '@/lib/http-api-client';
-import { toast } from 'sonner';
-
-const logger = createLogger('BoardBackground');
+import { useUpdateProjectSettings } from '@/hooks/mutations';
 
 /**
- * Hook for managing board background settings with automatic persistence to server
+ * Hook for managing board background settings with automatic persistence to server.
+ * Uses React Query mutation for server persistence with automatic error handling.
  */
 export function useBoardBackgroundSettings() {
   const store = useAppStore();
-  const httpClient = getHttpApiClient();
+
+  // Get the mutation without a fixed project path - we'll pass it with each call
+  const updateProjectSettings = useUpdateProjectSettings();
 
   // Helper to persist settings to server
   const persistSettings = useCallback(
-    async (projectPath: string, settingsToUpdate: Record<string, unknown>) => {
-      try {
-        const result = await httpClient.settings.updateProject(projectPath, {
-          boardBackground: settingsToUpdate,
-        });
-
-        if (!result.success) {
-          logger.error('Failed to persist settings:', result.error);
-          toast.error('Failed to save settings');
-        }
-      } catch (error) {
-        logger.error('Failed to persist settings:', error);
-        toast.error('Failed to save settings');
-      }
+    (projectPath: string, settingsToUpdate: Record<string, unknown>) => {
+      updateProjectSettings.mutate({
+        projectPath,
+        settings: { boardBackground: settingsToUpdate },
+      });
     },
-    [httpClient]
+    [updateProjectSettings]
   );
 
   // Get current background settings for a project
diff --git a/apps/ui/src/hooks/use-guided-prompts.ts b/apps/ui/src/hooks/use-guided-prompts.ts
index e192d6b3..e7d18e84 100644
--- a/apps/ui/src/hooks/use-guided-prompts.ts
+++ b/apps/ui/src/hooks/use-guided-prompts.ts
@@ -2,12 +2,12 @@
  * Hook for fetching guided prompts from the backend API
  *
  * This hook provides the single source of truth for guided prompts,
- * fetched from the backend /api/ideation/prompts endpoint.
+ * with caching via React Query.
  */
 
-import { useState, useEffect, useCallback } from 'react';
+import { useCallback, useMemo } from 'react';
 import type { IdeationPrompt, PromptCategory, IdeaCategory } from '@automaker/types';
-import { getElectronAPI } from '@/lib/electron';
+import { useIdeationPrompts } from '@/hooks/queries';
 
 interface UseGuidedPromptsReturn {
   prompts: IdeationPrompt[];
@@ -21,36 +21,10 @@ interface UseGuidedPromptsReturn {
 }
 
 export function useGuidedPrompts(): UseGuidedPromptsReturn {
-  const [prompts, setPrompts] = useState<IdeationPrompt[]>([]);
-  const [categories, setCategories] = useState<PromptCategory[]>([]);
-  const [isLoading, setIsLoading] = useState(true);
-  const [error, setError] = useState<string | null>(null);
+  const { data, isLoading, error, refetch } = useIdeationPrompts();
 
-  const fetchPrompts = useCallback(async () => {
-    setIsLoading(true);
-    setError(null);
-
-    try {
-      const api = getElectronAPI();
-      const result = await api.ideation?.getPrompts();
-
-      if (result?.success) {
-        setPrompts(result.prompts || []);
-        setCategories(result.categories || []);
-      } else {
-        setError(result?.error || 'Failed to fetch prompts');
-      }
-    } catch (err) {
-      console.error('Failed to fetch guided prompts:', err);
-      setError(err instanceof Error ? err.message : 'Failed to fetch prompts');
-    } finally {
-      setIsLoading(false);
-    }
-  }, []);
-
-  useEffect(() => {
-    fetchPrompts();
-  }, [fetchPrompts]);
+  const prompts = data?.prompts ?? [];
+  const categories = data?.categories ?? [];
 
   const getPromptsByCategory = useCallback(
     (category: IdeaCategory): IdeationPrompt[] => {
@@ -73,12 +47,23 @@ export function useGuidedPrompts(): UseGuidedPromptsReturn {
     [categories]
   );
 
+  // Convert async refetch to match the expected interface
+  const handleRefetch = useCallback(async () => {
+    await refetch();
+  }, [refetch]);
+
+  // Convert error to string for backward compatibility
+  const errorMessage = useMemo(() => {
+    if (!error) return null;
+    return error instanceof Error ? error.message : String(error);
+  }, [error]);
+
   return {
     prompts,
     categories,
     isLoading,
-    error,
-    refetch: fetchPrompts,
+    error: errorMessage,
+    refetch: handleRefetch,
     getPromptsByCategory,
     getPromptById,
     getCategoryById,
diff --git a/apps/ui/src/hooks/use-project-settings-loader.ts b/apps/ui/src/hooks/use-project-settings-loader.ts
index 4da50473..3f179942 100644
--- a/apps/ui/src/hooks/use-project-settings-loader.ts
+++ b/apps/ui/src/hooks/use-project-settings-loader.ts
@@ -1,11 +1,13 @@
 import { useEffect, useRef } from 'react';
 import { useAppStore } from '@/store/app-store';
-import { getHttpApiClient } from '@/lib/http-api-client';
+import { useProjectSettings } from '@/hooks/queries';
 
 /**
  * Hook that loads project settings from the server when the current project changes.
  * This ensures that settings like board backgrounds are properly restored when
  * switching between projects or restarting the app.
+ *
+ * Uses React Query for data fetching with automatic caching.
  */
 export function useProjectSettingsLoader() {
   const currentProject = useAppStore((state) => state.currentProject);
@@ -24,93 +26,84 @@ export function useProjectSettingsLoader() {
     (state) => state.setAutoDismissInitScriptIndicator
   );
 
-  const loadingRef = useRef<string | null>(null);
-  const currentProjectRef = useRef<string | null>(null);
+  const appliedProjectRef = useRef<string | null>(null);
 
+  // Fetch project settings with React Query
+  const { data: settings } = useProjectSettings(currentProject?.path);
+
+  // Apply settings when data changes
   useEffect(() => {
-    currentProjectRef.current = currentProject?.path ?? null;
-
-    if (!currentProject?.path) {
+    if (!currentProject?.path || !settings) {
       return;
     }
 
-    // Prevent loading the same project multiple times
-    if (loadingRef.current === currentProject.path) {
+    // Prevent applying the same settings multiple times
+    if (appliedProjectRef.current === currentProject.path) {
       return;
     }
 
-    loadingRef.current = currentProject.path;
-    const requestedProjectPath = currentProject.path;
+    appliedProjectRef.current = currentProject.path;
+    const projectPath = currentProject.path;
 
-    const loadProjectSettings = async () => {
-      try {
-        const httpClient = getHttpApiClient();
-        const result = await httpClient.settings.getProject(requestedProjectPath);
+    const bg = settings.boardBackground;
 
-        // Race condition protection: ignore stale results if project changed
-        if (currentProjectRef.current !== requestedProjectPath) {
-          return;
-        }
+    // Apply boardBackground if present
+    if (bg?.imagePath) {
+      setBoardBackground(projectPath, bg.imagePath);
+    }
 
-        if (result.success && result.settings) {
-          const bg = result.settings.boardBackground;
+    // Settings map for cleaner iteration
+    const settingsMap = {
+      cardOpacity: setCardOpacity,
+      columnOpacity: setColumnOpacity,
+      columnBorderEnabled: setColumnBorderEnabled,
+      cardGlassmorphism: setCardGlassmorphism,
+      cardBorderEnabled: setCardBorderEnabled,
+      cardBorderOpacity: setCardBorderOpacity,
+      hideScrollbar: setHideScrollbar,
+    } as const;
 
-          // Apply boardBackground if present
-          if (bg?.imagePath) {
-            setBoardBackground(requestedProjectPath, bg.imagePath);
-          }
-
-          // Settings map for cleaner iteration
-          const settingsMap = {
-            cardOpacity: setCardOpacity,
-            columnOpacity: setColumnOpacity,
-            columnBorderEnabled: setColumnBorderEnabled,
-            cardGlassmorphism: setCardGlassmorphism,
-            cardBorderEnabled: setCardBorderEnabled,
-            cardBorderOpacity: setCardBorderOpacity,
-            hideScrollbar: setHideScrollbar,
-          } as const;
-
-          // Apply all settings that are defined
-          for (const [key, setter] of Object.entries(settingsMap)) {
-            const value = bg?.[key as keyof typeof bg];
-            if (value !== undefined) {
-              (setter as (path: string, val: typeof value) => void)(requestedProjectPath, value);
-            }
-          }
-
-          // Apply worktreePanelVisible if present
-          if (result.settings.worktreePanelVisible !== undefined) {
-            setWorktreePanelVisible(requestedProjectPath, result.settings.worktreePanelVisible);
-          }
-
-          // Apply showInitScriptIndicator if present
-          if (result.settings.showInitScriptIndicator !== undefined) {
-            setShowInitScriptIndicator(
-              requestedProjectPath,
-              result.settings.showInitScriptIndicator
-            );
-          }
-
-          // Apply defaultDeleteBranch if present
-          if (result.settings.defaultDeleteBranch !== undefined) {
-            setDefaultDeleteBranch(requestedProjectPath, result.settings.defaultDeleteBranch);
-          }
-
-          // Apply autoDismissInitScriptIndicator if present
-          if (result.settings.autoDismissInitScriptIndicator !== undefined) {
-            setAutoDismissInitScriptIndicator(
-              requestedProjectPath,
-              result.settings.autoDismissInitScriptIndicator
-            );
-          }
-        }
-      } catch (error) {
-        console.error('Failed to load project settings:', error);
-        // Don't show error toast - just log it
+    // Apply all settings that are defined
+    for (const [key, setter] of Object.entries(settingsMap)) {
+      const value = bg?.[key as keyof typeof bg];
+      if (value !== undefined) {
+        (setter as (path: string, val: typeof value) => void)(projectPath, value);
       }
-    };
+    }
 
-    loadProjectSettings();
-  }, [currentProject?.path]);
+    // Apply worktreePanelVisible if present
+    if (settings.worktreePanelVisible !== undefined) {
+      setWorktreePanelVisible(projectPath, settings.worktreePanelVisible);
+    }
+
+    // Apply showInitScriptIndicator if present
+    if (settings.showInitScriptIndicator !== undefined) {
+      setShowInitScriptIndicator(projectPath, settings.showInitScriptIndicator);
+    }
+
+    // Apply defaultDeleteBranchWithWorktree if present
+    if (settings.defaultDeleteBranchWithWorktree !== undefined) {
+      setDefaultDeleteBranch(projectPath, settings.defaultDeleteBranchWithWorktree);
+    }
+
+    // Apply autoDismissInitScriptIndicator if present
+    if (settings.autoDismissInitScriptIndicator !== undefined) {
+      setAutoDismissInitScriptIndicator(projectPath, settings.autoDismissInitScriptIndicator);
+    }
+  }, [
+    currentProject?.path,
+    settings,
+    setBoardBackground,
+    setCardOpacity,
+    setColumnOpacity,
+    setColumnBorderEnabled,
+    setCardGlassmorphism,
+    setCardBorderEnabled,
+    setCardBorderOpacity,
+    setHideScrollbar,
+    setWorktreePanelVisible,
+    setShowInitScriptIndicator,
+    setDefaultDeleteBranch,
+    setAutoDismissInitScriptIndicator,
+  ]);
 }