feat: Add AI-generated commit messages

Integrate Claude Haiku to automatically generate commit messages when
committing worktree changes. Shows a sparkle animation while generating
and auto-populates the commit message field.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/server/src/routes/worktree/index.ts

@@ -17,6 +17,7 @@ import { createDeleteHandler } from './routes/delete.js';
 import { createCreatePRHandler } from './routes/create-pr.js';
 import { createPRInfoHandler } from './routes/pr-info.js';
 import { createCommitHandler } from './routes/commit.js';
+import { createGenerateCommitMessageHandler } from './routes/generate-commit-message.js';
 import { createPushHandler } from './routes/push.js';
 import { createPullHandler } from './routes/pull.js';
 import { createCheckoutBranchHandler } from './routes/checkout-branch.js';
@@ -64,6 +65,12 @@ export function createWorktreeRoutes(events: EventEmitter): Router {
     requireGitRepoOnly,
     createCommitHandler()
   );
+  router.post(
+    '/generate-commit-message',
+    validatePathParams('worktreePath'),
+    requireGitRepoOnly,
+    createGenerateCommitMessageHandler()
+  );
   router.post(
     '/push',
     validatePathParams('worktreePath'),

apps/server/src/routes/worktree/routes/generate-commit-message.ts

@@ -0,0 +1,178 @@
+/**
+ * POST /worktree/generate-commit-message endpoint - Generate an AI commit message from git diff
+ *
+ * Uses Claude Haiku to generate a concise, conventional commit message from git changes.
+ */
+
+import type { Request, Response } from 'express';
+import { exec } from 'child_process';
+import { promisify } from 'util';
+import { query } from '@anthropic-ai/claude-agent-sdk';
+import { createLogger } from '@automaker/utils';
+import { CLAUDE_MODEL_MAP } from '@automaker/model-resolver';
+import { getErrorMessage, logError } from '../common.js';
+
+const logger = createLogger('GenerateCommitMessage');
+const execAsync = promisify(exec);
+
+interface GenerateCommitMessageRequestBody {
+  worktreePath: string;
+}
+
+interface GenerateCommitMessageSuccessResponse {
+  success: true;
+  message: string;
+}
+
+interface GenerateCommitMessageErrorResponse {
+  success: false;
+  error: string;
+}
+
+const SYSTEM_PROMPT = `You are a git commit message generator. Your task is to create a clear, concise commit message based on the git diff provided.
+
+Rules:
+- Output ONLY the commit message, nothing else
+- First line should be a short summary (50 chars or less) in imperative mood
+- Start with a conventional commit type if appropriate (feat:, fix:, refactor:, docs:, etc.)
+- Keep it concise and descriptive
+- Focus on WHAT changed and WHY (if clear from the diff), not HOW
+- No quotes, backticks, or extra formatting
+- If there are multiple changes, provide a brief summary on the first line
+
+Examples:
+- feat: Add dark mode toggle to settings
+- fix: Resolve login validation edge case
+- refactor: Extract user authentication logic
+- docs: Update installation instructions`;
+
+async function extractTextFromStream(
+  stream: AsyncIterable<{
+    type: string;
+    subtype?: string;
+    result?: string;
+    message?: {
+      content?: Array<{ type: string; text?: string }>;
+    };
+  }>
+): Promise<string> {
+  let responseText = '';
+
+  for await (const msg of stream) {
+    if (msg.type === 'assistant' && msg.message?.content) {
+      for (const block of msg.message.content) {
+        if (block.type === 'text' && block.text) {
+          responseText += block.text;
+        }
+      }
+    } else if (msg.type === 'result' && msg.subtype === 'success') {
+      responseText = msg.result || responseText;
+    }
+  }
+
+  return responseText;
+}
+
+export function createGenerateCommitMessageHandler(): (
+  req: Request,
+  res: Response
+) => Promise<void> {
+  return async (req: Request, res: Response): Promise<void> => {
+    try {
+      const { worktreePath } = req.body as GenerateCommitMessageRequestBody;
+
+      if (!worktreePath || typeof worktreePath !== 'string') {
+        const response: GenerateCommitMessageErrorResponse = {
+          success: false,
+          error: 'worktreePath is required and must be a string',
+        };
+        res.status(400).json(response);
+        return;
+      }
+
+      logger.info(`Generating commit message for worktree: ${worktreePath}`);
+
+      // Get git diff of staged and unstaged changes
+      let diff = '';
+      try {
+        // First try to get staged changes
+        const { stdout: stagedDiff } = await execAsync('git diff --cached', {
+          cwd: worktreePath,
+          maxBuffer: 1024 * 1024 * 5, // 5MB buffer
+        });
+
+        // If no staged changes, get unstaged changes
+        if (!stagedDiff.trim()) {
+          const { stdout: unstagedDiff } = await execAsync('git diff', {
+            cwd: worktreePath,
+            maxBuffer: 1024 * 1024 * 5, // 5MB buffer
+          });
+          diff = unstagedDiff;
+        } else {
+          diff = stagedDiff;
+        }
+      } catch (error) {
+        logger.error('Failed to get git diff:', error);
+        const response: GenerateCommitMessageErrorResponse = {
+          success: false,
+          error: 'Failed to get git changes',
+        };
+        res.status(500).json(response);
+        return;
+      }
+
+      if (!diff.trim()) {
+        const response: GenerateCommitMessageErrorResponse = {
+          success: false,
+          error: 'No changes to commit',
+        };
+        res.status(400).json(response);
+        return;
+      }
+
+      // Truncate diff if too long (keep first 10000 characters to avoid token limits)
+      const truncatedDiff =
+        diff.length > 10000 ? diff.substring(0, 10000) + '\n\n[... diff truncated ...]' : diff;
+
+      const userPrompt = `Generate a commit message for these changes:\n\n\`\`\`diff\n${truncatedDiff}\n\`\`\``;
+
+      const stream = query({
+        prompt: userPrompt,
+        options: {
+          model: CLAUDE_MODEL_MAP.haiku,
+          systemPrompt: SYSTEM_PROMPT,
+          maxTurns: 1,
+          allowedTools: [],
+          permissionMode: 'default',
+        },
+      });
+
+      const message = await extractTextFromStream(stream);
+
+      if (!message || message.trim().length === 0) {
+        logger.warn('Received empty response from Claude');
+        const response: GenerateCommitMessageErrorResponse = {
+          success: false,
+          error: 'Failed to generate commit message - empty response',
+        };
+        res.status(500).json(response);
+        return;
+      }
+
+      logger.info(`Generated commit message: ${message.trim().substring(0, 100)}...`);
+
+      const response: GenerateCommitMessageSuccessResponse = {
+        success: true,
+        message: message.trim(),
+      };
+      res.json(response);
+    } catch (error) {
+      logError(error, 'Generate commit message failed');
+      const response: GenerateCommitMessageErrorResponse = {
+        success: false,
+        error: getErrorMessage(error),
+      };
+      res.status(500).json(response);
+    }
+  };
+}

apps/ui/src/components/views/board-view/dialogs/commit-worktree-dialog.tsx

@@ -1,4 +1,4 @@
-import { useState } from 'react';
+import { useState, useEffect } from 'react';
 import {
   Dialog,
   DialogContent,
@@ -10,7 +10,7 @@ import {
 import { Button } from '@/components/ui/button';
 import { Textarea } from '@/components/ui/textarea';
 import { Label } from '@/components/ui/label';
-import { GitCommit, Loader2 } from 'lucide-react';
+import { GitCommit, Loader2, Sparkles } from 'lucide-react';
 import { getElectronAPI } from '@/lib/electron';
 import { toast } from 'sonner';
 
@@ -37,6 +37,7 @@ export function CommitWorktreeDialog({
 }: CommitWorktreeDialogProps) {
   const [message, setMessage] = useState('');
   const [isLoading, setIsLoading] = useState(false);
+  const [isGenerating, setIsGenerating] = useState(false);
   const [error, setError] = useState<string | null>(null);
 
   const handleCommit = async () => {
@@ -82,6 +83,45 @@ export function CommitWorktreeDialog({
     }
   };
 
+  // Generate AI commit message when dialog opens
+  useEffect(() => {
+    if (open && worktree) {
+      // Reset state
+      setMessage('');
+      setError(null);
+      setIsGenerating(true);
+
+      const generateMessage = async () => {
+        try {
+          const api = getElectronAPI();
+          if (!api?.worktree?.generateCommitMessage) {
+            setError('AI commit message generation not available');
+            setIsGenerating(false);
+            return;
+          }
+
+          const result = await api.worktree.generateCommitMessage(worktree.path);
+
+          if (result.success && result.message) {
+            setMessage(result.message);
+          } else {
+            // Don't show error toast, just log it and leave message empty
+            console.warn('Failed to generate commit message:', result.error);
+            setMessage('');
+          }
+        } catch (err) {
+          // Don't show error toast for generation failures
+          console.warn('Error generating commit message:', err);
+          setMessage('');
+        } finally {
+          setIsGenerating(false);
+        }
+      };
+
+      generateMessage();
+    }
+  }, [open, worktree]);
+
   if (!worktree) return null;
 
   return (
@@ -106,10 +146,20 @@ export function CommitWorktreeDialog({
 
         <div className="grid gap-4 py-4">
           <div className="grid gap-2">
-            <Label htmlFor="commit-message">Commit Message</Label>
+            <Label htmlFor="commit-message" className="flex items-center gap-2">
+              Commit Message
+              {isGenerating && (
+                <span className="flex items-center gap-1 text-xs text-muted-foreground">
+                  <Sparkles className="w-3 h-3 animate-pulse" />
+                  Generating...
+                </span>
+              )}
+            </Label>
             <Textarea
               id="commit-message"
-              placeholder="Describe your changes..."
+              placeholder={
+                isGenerating ? 'Generating commit message...' : 'Describe your changes...'
+              }
               value={message}
               onChange={(e) => {
                 setMessage(e.target.value);
@@ -118,6 +168,7 @@ export function CommitWorktreeDialog({
               onKeyDown={handleKeyDown}
               className="min-h-[100px] font-mono text-sm"
               autoFocus
+              disabled={isGenerating}
             />
             {error && <p className="text-sm text-destructive">{error}</p>}
           </div>
@@ -128,10 +179,14 @@ export function CommitWorktreeDialog({
         </div>
 
         <DialogFooter>
-          <Button variant="ghost" onClick={() => onOpenChange(false)} disabled={isLoading}>
+          <Button
+            variant="ghost"
+            onClick={() => onOpenChange(false)}
+            disabled={isLoading || isGenerating}
+          >
             Cancel
           </Button>
-          <Button onClick={handleCommit} disabled={isLoading || !message.trim()}>
+          <Button onClick={handleCommit} disabled={isLoading || isGenerating || !message.trim()}>
             {isLoading ? (
               <>
                 <Loader2 className="w-4 h-4 mr-2 animate-spin" />

apps/ui/src/lib/electron.ts

@@ -1537,6 +1537,15 @@ function createMockWorktreeAPI(): WorktreeAPI {
       };
     },
 
+    generateCommitMessage: async (worktreePath: string) => {
+      console.log('[Mock] Generating commit message:', { worktreePath });
+      return {
+        success: true,
+        message:
+          'feat: Add new feature implementation\n\nThis is a mock AI-generated commit message.',
+      };
+    },
+
     push: async (worktreePath: string, force?: boolean) => {
       console.log('[Mock] Pushing worktree:', { worktreePath, force });
       return {

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

@@ -1681,6 +1681,8 @@ export class HttpApiClient implements ElectronAPI {
       }),
     commit: (worktreePath: string, message: string) =>
       this.post('/api/worktree/commit', { worktreePath, message }),
+    generateCommitMessage: (worktreePath: string) =>
+      this.post('/api/worktree/generate-commit-message', { worktreePath }),
     push: (worktreePath: string, force?: boolean) =>
       this.post('/api/worktree/push', { worktreePath, force }),
     createPR: (worktreePath: string, options?: any) =>

apps/ui/src/types/electron.d.ts

@@ -770,6 +770,13 @@ export interface WorktreeAPI {
     error?: string;
   }>;
 
+  // Generate an AI commit message from git diff
+  generateCommitMessage: (worktreePath: string) => Promise<{
+    success: boolean;
+    message?: string;
+    error?: string;
+  }>;
+
   // Push a worktree branch to remote
   push: (
     worktreePath: string,

libs/git-utils/src/diff.ts

@@ -98,7 +98,7 @@ Binary file ${cleanPath} added
     const lines = content.split('\n');
 
     // Remove trailing empty line if the file ends with newline
-    if (lines.length > 0 && lines.at(-1) === '') {
+    if (lines.length > 0 && lines[lines.length - 1] === '') {
       lines.pop();
     }