feat(worktree): add AI commit message generation feature

- Implemented a new endpoint to generate commit messages based on git diffs.
- Updated worktree routes to include the AI commit message generation functionality.
- Enhanced the UI to support automatic generation of commit messages when the commit dialog opens, based on user settings.
- Added settings for enabling/disabling AI-generated commit messages and configuring the model used for generation.

apps/ui/src/components/views/settings-view/feature-defaults/feature-defaults-section.tsx

@@ -10,6 +10,7 @@ import {
   ScrollText,
   ShieldCheck,
   FastForward,
+  Sparkles,
 } from 'lucide-react';
 import { cn } from '@/lib/utils';
 import {
@@ -28,11 +29,13 @@ interface FeatureDefaultsSectionProps {
   skipVerificationInAutoMode: boolean;
   defaultPlanningMode: PlanningMode;
   defaultRequirePlanApproval: boolean;
+  enableAiCommitMessages: boolean;
   onDefaultSkipTestsChange: (value: boolean) => void;
   onEnableDependencyBlockingChange: (value: boolean) => void;
   onSkipVerificationInAutoModeChange: (value: boolean) => void;
   onDefaultPlanningModeChange: (value: PlanningMode) => void;
   onDefaultRequirePlanApprovalChange: (value: boolean) => void;
+  onEnableAiCommitMessagesChange: (value: boolean) => void;
 }
 
 export function FeatureDefaultsSection({
@@ -41,11 +44,13 @@ export function FeatureDefaultsSection({
   skipVerificationInAutoMode,
   defaultPlanningMode,
   defaultRequirePlanApproval,
+  enableAiCommitMessages,
   onDefaultSkipTestsChange,
   onEnableDependencyBlockingChange,
   onSkipVerificationInAutoModeChange,
   onDefaultPlanningModeChange,
   onDefaultRequirePlanApprovalChange,
+  onEnableAiCommitMessagesChange,
 }: FeatureDefaultsSectionProps) {
   return (
     <div
@@ -251,6 +256,34 @@ export function FeatureDefaultsSection({
             </p>
           </div>
         </div>
+
+        {/* Separator */}
+        <div className="border-t border-border/30" />
+
+        {/* AI Commit Messages Setting */}
+        <div className="group flex items-start space-x-3 p-3 rounded-xl hover:bg-accent/30 transition-colors duration-200 -mx-3">
+          <Checkbox
+            id="enable-ai-commit-messages"
+            checked={enableAiCommitMessages}
+            onCheckedChange={(checked) => onEnableAiCommitMessagesChange(checked === true)}
+            className="mt-1"
+            data-testid="enable-ai-commit-messages-checkbox"
+          />
+          <div className="space-y-1.5">
+            <Label
+              htmlFor="enable-ai-commit-messages"
+              className="text-foreground cursor-pointer font-medium flex items-center gap-2"
+            >
+              <Sparkles className="w-4 h-4 text-brand-500" />
+              Generate AI commit messages
+            </Label>
+            <p className="text-xs text-muted-foreground/80 leading-relaxed">
+              When enabled, opening the commit dialog will automatically generate a commit message
+              using AI based on your staged or unstaged changes. You can configure the model used in
+              Model Defaults.
+            </p>
+          </div>
+        </div>
       </div>
     </div>
   );

apps/ui/src/components/views/settings-view/model-defaults/model-defaults-section.tsx

@@ -28,6 +28,11 @@ const QUICK_TASKS: PhaseConfig[] = [
     label: 'Image Descriptions',
     description: 'Analyzes and describes context images',
   },
+  {
+    key: 'commitMessageModel',
+    label: 'Commit Messages',
+    description: 'Generates git commit messages from diffs',
+  },
 ];
 
 const VALIDATION_TASKS: PhaseConfig[] = [