feat: add discard changes functionality for worktrees

- Introduced a new POST /discard-changes endpoint to discard all uncommitted changes in a worktree, including resetting staged changes, discarding modifications to tracked files, and removing untracked files.
- Implemented a corresponding handler in the UI to confirm and execute the discard operation, enhancing user control over worktree changes.
- Added a ViewWorktreeChangesDialog component to display changes in the worktree, improving the user experience for managing worktree states.
- Updated the WorktreePanel and WorktreeActionsDropdown components to integrate the new functionality, allowing users to view and discard changes directly from the UI.

This update streamlines the management of worktree changes, providing users with essential tools for version control.

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

@@ -48,6 +48,7 @@ import {
   createDeleteInitScriptHandler,
   createRunInitScriptHandler,
 } from './routes/init-script.js';
+import { createDiscardChangesHandler } from './routes/discard-changes.js';
 import type { SettingsService } from '../../services/settings-service.js';
 
 export function createWorktreeRoutes(
@@ -148,5 +149,13 @@ export function createWorktreeRoutes(
     createRunInitScriptHandler(events)
   );
 
+  // Discard changes route
+  router.post(
+    '/discard-changes',
+    validatePathParams('worktreePath'),
+    requireGitRepoOnly,
+    createDiscardChangesHandler()
+  );
+
   return router;
 }

apps/server/src/routes/worktree/routes/discard-changes.ts

@@ -0,0 +1,112 @@
+/**
+ * POST /discard-changes endpoint - Discard all uncommitted changes in a worktree
+ *
+ * This performs a destructive operation that:
+ * 1. Resets staged changes (git reset HEAD)
+ * 2. Discards modified tracked files (git checkout .)
+ * 3. Removes untracked files and directories (git clean -fd)
+ *
+ * Note: Git repository validation (isGitRepo) is handled by
+ * the requireGitRepoOnly middleware in index.ts
+ */
+
+import type { Request, Response } from 'express';
+import { exec } from 'child_process';
+import { promisify } from 'util';
+import { getErrorMessage, logError } from '../common.js';
+
+const execAsync = promisify(exec);
+
+export function createDiscardChangesHandler() {
+  return async (req: Request, res: Response): Promise<void> => {
+    try {
+      const { worktreePath } = req.body as {
+        worktreePath: string;
+      };
+
+      if (!worktreePath) {
+        res.status(400).json({
+          success: false,
+          error: 'worktreePath required',
+        });
+        return;
+      }
+
+      // Check for uncommitted changes first
+      const { stdout: status } = await execAsync('git status --porcelain', {
+        cwd: worktreePath,
+      });
+
+      if (!status.trim()) {
+        res.json({
+          success: true,
+          result: {
+            discarded: false,
+            message: 'No changes to discard',
+          },
+        });
+        return;
+      }
+
+      // Count the files that will be affected
+      const lines = status.trim().split('\n').filter(Boolean);
+      const fileCount = lines.length;
+
+      // Get branch name before discarding
+      const { stdout: branchOutput } = await execAsync('git rev-parse --abbrev-ref HEAD', {
+        cwd: worktreePath,
+      });
+      const branchName = branchOutput.trim();
+
+      // Discard all changes:
+      // 1. Reset any staged changes
+      await execAsync('git reset HEAD', { cwd: worktreePath }).catch(() => {
+        // Ignore errors - might fail if there's nothing staged
+      });
+
+      // 2. Discard changes in tracked files
+      await execAsync('git checkout .', { cwd: worktreePath }).catch(() => {
+        // Ignore errors - might fail if there are no tracked changes
+      });
+
+      // 3. Remove untracked files and directories
+      await execAsync('git clean -fd', { cwd: worktreePath }).catch(() => {
+        // Ignore errors - might fail if there are no untracked files
+      });
+
+      // Verify all changes were discarded
+      const { stdout: finalStatus } = await execAsync('git status --porcelain', {
+        cwd: worktreePath,
+      });
+
+      if (finalStatus.trim()) {
+        // Some changes couldn't be discarded (possibly ignored files or permission issues)
+        const remainingCount = finalStatus.trim().split('\n').filter(Boolean).length;
+        res.json({
+          success: true,
+          result: {
+            discarded: true,
+            filesDiscarded: fileCount - remainingCount,
+            filesRemaining: remainingCount,
+            branch: branchName,
+            message: `Discarded ${fileCount - remainingCount} files, ${remainingCount} files could not be removed`,
+          },
+        });
+      } else {
+        res.json({
+          success: true,
+          result: {
+            discarded: true,
+            filesDiscarded: fileCount,
+            filesRemaining: 0,
+            branch: branchName,
+            message: `Discarded ${fileCount} ${fileCount === 1 ? 'file' : 'files'}`,
+          },
+        });
+      }
+    } catch (error) {
+      logError(error, 'Discard changes failed');
+      res.status(500).json({ success: false, error: getErrorMessage(error) });
+    }
+  };
+}