fix(git): run post-checkout hook after worktree creation bootstrap (#2721)

Worktrees are created with `git worktree add --no-checkout` and populated
with `git reset --hard`, neither of which runs git's post-checkout hook.
Invoke the hook explicitly after population with git's standard arguments
(null ref previous HEAD, checked-out HEAD, flag 1) and the worktree as cwd,
mirroring `git worktree add` without --no-checkout.

A missing or non-executable hook is skipped (matching git) and a failing
hook is logged as a warning, never failing worktree creation or session
bootstrap. Applied to both the web server git service and the VS Code
runtime's git service.

packages/vscode/src/gitService.ts

@@ -33,6 +33,7 @@ const WORKTREE_PHASE_GIT_READY = 'git-ready' as const;
 const WORKTREE_PHASE_SETUP_READY = 'setup-ready' as const;
 const WORKTREE_INDEX_LOCK_RETRY_DELAY_MS = 250;
 const WORKTREE_INDEX_LOCK_STALE_DELAY_MS = 750;
+const GIT_NULL_REF = '0'.repeat(40);
 
 const toBootstrapStateKey = (directory: string): string => {
   const normalized = normalizeDirectoryPath(directory);
@@ -1154,6 +1155,62 @@ const populateWorktreeWithLockRecovery = async (directory: string): Promise<void
   await runGitCommandOrThrow(directory, ['reset', '--hard'], 'Failed to populate worktree');
 };
 
+// Worktrees are created with `git worktree add --no-checkout` and populated
+// with `git reset --hard`, neither of which runs git's post-checkout hook —
+// git only runs it for checkouts, clone, and worktree add *without*
+// --no-checkout. Invoke the hook explicitly after population to restore git's
+// checkout semantics: git passes the previous HEAD (null ref for a brand-new
+// worktree), the new HEAD, and flag 1 for a branch checkout, and runs the hook
+// from the worktree top-level.
+const runPostCheckoutHook = async (directory: string): Promise<void> => {
+  let hookDirectory: string | null = null;
+  try {
+    const result = await runGitCommand(directory, ['rev-parse', '--git-path', 'hooks']);
+    if (!result.success) return;
+    hookDirectory = normalizeDirectoryPath(String(result.stdout || '').trim());
+  } catch {
+    return;
+  }
+  if (!hookDirectory) return;
+
+  const hookPath = path.join(hookDirectory, 'post-checkout');
+  try {
+    const stat = await fs.promises.stat(hookPath);
+    if (!stat.isFile()) return;
+    if (process.platform !== 'win32') {
+      await fs.promises.access(hookPath, fs.constants.X_OK);
+    }
+  } catch {
+    // Missing or non-executable hooks are skipped, matching git.
+    return;
+  }
+
+  const [headResult, gitDirResult] = await Promise.all([
+    runGitCommand(directory, ['rev-parse', 'HEAD']),
+    runGitCommand(directory, ['rev-parse', '--absolute-git-dir']),
+  ]);
+  if (!headResult.success || !gitDirResult.success) return;
+  const head = String(headResult.stdout || '').trim();
+  const gitDir = String(gitDirResult.stdout || '').trim();
+  if (!head || !gitDir) return;
+
+  try {
+    await execFileAsync(hookPath, [GIT_NULL_REF, head, '1'], {
+      cwd: directory,
+      env: {
+        ...(await buildGitEnv()),
+        GIT_DIR: gitDir,
+        GIT_WORK_TREE: path.resolve(directory),
+      },
+      windowsHide: true,
+    });
+  } catch (error) {
+    // A failing hook must not fail worktree creation or session bootstrap:
+    // warn and continue.
+    console.warn('[GitService] post-checkout hook failed in worktree:', error instanceof Error ? error.message : String(error));
+  }
+};
+
 const ensureOpenCodeProjectId = async (primaryWorktree: string): Promise<string> => {
   const gitDir = path.join(primaryWorktree, '.git');
   const idFile = path.join(gitDir, 'opencode');
@@ -1478,6 +1535,7 @@ const queueWorktreeBootstrap = (args: {
   const task = new Promise<void>((resolve) => setTimeout(resolve, 0))
     .then(async () => {
       await populateWorktreeWithLockRecovery(directory);
+      await runPostCheckoutHook(directory);
       if (setUpstream) {
         await applyUpstreamConfiguration({
           primaryWorktree,

packages/web/server/lib/git/DOCUMENTATION.md

@@ -48,7 +48,7 @@ The following functions are exported and used by the web server:
 ### Worktree Operations
 - `getWorktrees(directory)`: List all git worktrees for a repository.
 - `validateWorktreeCreate(directory, input)`: Validate worktree creation parameters (mode, branchName, startRef, upstream config).
-- `createWorktree(directory, input)`: Create a new worktree (supports 'new' and 'existing' modes, upstream setup).
+- `createWorktree(directory, input)`: Create a new worktree (supports 'new' and 'existing' modes, upstream setup). After populating the worktree, the repository's `post-checkout` hook runs once with git's standard arguments (null ref as previous HEAD, the checked-out HEAD, and flag `1`) from the worktree directory, mirroring `git worktree add` without `--no-checkout`; a missing or non-executable hook is skipped and a failing hook is logged as a warning, never failing worktree creation or the session bootstrap.
 - `removeWorktree(directory, input)`: Remove a worktree (optionally delete local branch).
 - `isLinkedWorktree(directory)`: Check if directory is a linked worktree (not primary).
 
@@ -95,6 +95,7 @@ The following functions are internal helpers used by exported functions:
 - `resolveCandidateDirectory(...)`: Generate unique worktree directory candidates.
 - `resolveBranchForExistingMode(...)`: Resolve branch for existing-mode worktree creation.
 - `applyUpstreamConfiguration(...)`: Set upstream tracking for new branches.
+- `runPostCheckoutHook(directory)`: Invoke the worktree's `post-checkout` hook after population, because `git worktree add --no-checkout` and the bootstrap's `git reset --hard` never run git hooks. Runs with git's standard arguments and the worktree as cwd; skips missing/non-executable hooks and never throws on hook failure.
 - And various other internal helpers for Git command execution and parsing.
 
 ## Response Contracts

packages/web/server/lib/git/service.js

@@ -25,6 +25,7 @@ const WORKTREE_BOOTSTRAP_FAILED = 'failed';
 const WORKTREE_BOOTSTRAP_PHASE_DIRECTORY_CREATED = 'directory-created';
 const WORKTREE_BOOTSTRAP_PHASE_GIT_READY = 'git-ready';
 const WORKTREE_BOOTSTRAP_PHASE_SETUP_READY = 'setup-ready';
+const GIT_NULL_REF = '0'.repeat(40);
 const WORKTREE_INDEX_LOCK_RETRY_DELAY_MS = 250;
 const WORKTREE_INDEX_LOCK_STALE_DELAY_MS = 750;
 
@@ -1028,6 +1029,62 @@ export const populateWorktreeWithLockRecovery = async (directory) => {
   await runGitCommandOrThrow(directory, ['reset', '--hard'], 'Failed to populate worktree');
 };
 
+// Worktrees are created with `git worktree add --no-checkout` and populated
+// with `git reset --hard`, neither of which runs git's post-checkout hook —
+// git only runs it for checkouts, clone, and worktree add *without*
+// --no-checkout. Invoke the hook explicitly after population to restore git's
+// checkout semantics: git passes the previous HEAD (null ref for a brand-new
+// worktree), the new HEAD, and flag 1 for a branch checkout, and runs the hook
+// from the worktree top-level.
+const runPostCheckoutHook = async (directory) => {
+  let hookDirectory = null;
+  try {
+    const result = await runGitCommand(directory, ['rev-parse', '--git-path', 'hooks']);
+    if (!result.success) return;
+    hookDirectory = normalizeDirectoryPath(String(result.stdout || '').trim());
+  } catch {
+    return;
+  }
+  if (!hookDirectory) return;
+
+  const hookPath = path.join(hookDirectory, 'post-checkout');
+  try {
+    const stat = await fsp.stat(hookPath);
+    if (!stat.isFile()) return;
+    if (process.platform !== 'win32') {
+      await fsp.access(hookPath, fs.constants.X_OK);
+    }
+  } catch {
+    // Missing or non-executable hooks are skipped, matching git.
+    return;
+  }
+
+  const [headResult, gitDirResult] = await Promise.all([
+    runGitCommand(directory, ['rev-parse', 'HEAD']),
+    runGitCommand(directory, ['rev-parse', '--absolute-git-dir']),
+  ]);
+  if (!headResult.success || !gitDirResult.success) return;
+  const head = String(headResult.stdout || '').trim();
+  const gitDir = String(gitDirResult.stdout || '').trim();
+  if (!head || !gitDir) return;
+
+  try {
+    await execFileAsync(hookPath, [GIT_NULL_REF, head, '1'], {
+      cwd: directory,
+      env: {
+        ...(await buildGitEnv()),
+        GIT_DIR: gitDir,
+        GIT_WORK_TREE: path.resolve(directory),
+      },
+      windowsHide: true,
+    });
+  } catch (error) {
+    // A failing hook must not fail worktree creation or session bootstrap:
+    // warn and continue.
+    console.warn(`[GitService] post-checkout hook failed in worktree ${directory}: ${error instanceof Error ? error.message : String(error)}`);
+  }
+};
+
 const derivePrimaryWorktreeRootFromGitDir = (gitDir) => {
   const normalized = normalizePath(gitDir);
   if (!normalized) return null;
@@ -1719,6 +1776,7 @@ const queueWorktreeBootstrap = (args) => {
   const task = new Promise((resolve) => setTimeout(resolve, 0))
     .then(async () => {
       await populateWorktreeWithLockRecovery(directory);
+      await runPostCheckoutHook(directory);
       if (setUpstream) {
         await applyUpstreamConfiguration({
           primaryWorktree,

packages/web/server/lib/git/service.test.js

@@ -537,6 +537,154 @@ describe('createWorktree', () => {
     }
   });
 
+  const installPostCheckoutHook = (repo, script, executable = true) => {
+    const hookPath = path.join(repo, '.git', 'hooks', 'post-checkout');
+    fs.writeFileSync(hookPath, script);
+    if (executable) {
+      fs.chmodSync(hookPath, 0o755);
+    }
+    return hookPath;
+  };
+
+  it('runs the post-checkout hook after populating a created worktree', async () => {
+    if (!canRunGit()) return;
+
+    const previousXdgDataHome = process.env.XDG_DATA_HOME;
+    const dataHome = createTempDir();
+    process.env.XDG_DATA_HOME = dataHome;
+
+    try {
+      const repo = createTempDir();
+      runGit(repo, ['init', '-b', 'main']);
+      runGit(repo, ['config', 'user.email', 'test@example.com']);
+      runGit(repo, ['config', 'user.name', 'Test User']);
+      fs.writeFileSync(path.join(repo, 'README.md'), '# Test\n');
+      runGit(repo, ['add', 'README.md']);
+      runGit(repo, ['commit', '-m', 'Initial commit']);
+      const head = runGit(repo, ['rev-parse', 'HEAD']).trim();
+
+      const hookLog = path.join(dataHome, 'post-checkout.log');
+      installPostCheckoutHook(
+        repo,
+        `#!/bin/sh\nprintf '%s|%s|%s|%s' "$1" "$2" "$3" "$(pwd -P)" > ${JSON.stringify(hookLog)}\n`,
+      );
+
+      const created = await createWorktree(repo, {
+        mode: 'new',
+        worktreeName: 'hook-test',
+        branchName: 'openchamber/hook-test',
+        returnAfterDirectoryCreated: true,
+      });
+
+      await expect.poll(() => {
+        try {
+          return fs.readFileSync(hookLog, 'utf8');
+        } catch {
+          return '';
+        }
+      }, { timeout: 5_000 }).not.toBe('');
+
+      const [previousHead, newHead, flag, cwd] = fs.readFileSync(hookLog, 'utf8').split('|');
+      expect(previousHead).toBe('0000000000000000000000000000000000000000');
+      expect(newHead).toBe(head);
+      expect(flag).toBe('1');
+      expect(cwd).toBe(fs.realpathSync(created.path));
+    } finally {
+      if (previousXdgDataHome === undefined) {
+        delete process.env.XDG_DATA_HOME;
+      } else {
+        process.env.XDG_DATA_HOME = previousXdgDataHome;
+      }
+    }
+  });
+
+  it('skips a non-executable post-checkout hook', async () => {
+    if (!canRunGit()) return;
+
+    const previousXdgDataHome = process.env.XDG_DATA_HOME;
+    const dataHome = createTempDir();
+    process.env.XDG_DATA_HOME = dataHome;
+
+    try {
+      const repo = createTempDir();
+      runGit(repo, ['init', '-b', 'main']);
+      runGit(repo, ['config', 'user.email', 'test@example.com']);
+      runGit(repo, ['config', 'user.name', 'Test User']);
+      fs.writeFileSync(path.join(repo, 'README.md'), '# Test\n');
+      runGit(repo, ['add', 'README.md']);
+      runGit(repo, ['commit', '-m', 'Initial commit']);
+
+      const hookLog = path.join(dataHome, 'post-checkout-skipped.log');
+      installPostCheckoutHook(
+        repo,
+        `#!/bin/sh\nprintf 'ran' > ${JSON.stringify(hookLog)}\n`,
+        false,
+      );
+
+      const created = await createWorktree(repo, {
+        mode: 'new',
+        worktreeName: 'hook-skip-test',
+        branchName: 'openchamber/hook-skip-test',
+        returnAfterDirectoryCreated: true,
+      });
+
+      await expect.poll(
+        async () => (await getWorktreeBootstrapStatus(created.path)).status,
+        { timeout: 5_000 },
+      ).toBe('ready');
+      expect(fs.existsSync(hookLog)).toBe(false);
+    } finally {
+      if (previousXdgDataHome === undefined) {
+        delete process.env.XDG_DATA_HOME;
+      } else {
+        process.env.XDG_DATA_HOME = previousXdgDataHome;
+      }
+    }
+  });
+
+  it('does not fail worktree bootstrap when the post-checkout hook fails', async () => {
+    if (!canRunGit()) return;
+
+    const previousXdgDataHome = process.env.XDG_DATA_HOME;
+    const dataHome = createTempDir();
+    process.env.XDG_DATA_HOME = dataHome;
+
+    try {
+      const repo = createTempDir();
+      runGit(repo, ['init', '-b', 'main']);
+      runGit(repo, ['config', 'user.email', 'test@example.com']);
+      runGit(repo, ['config', 'user.name', 'Test User']);
+      fs.writeFileSync(path.join(repo, 'README.md'), '# Test\n');
+      runGit(repo, ['add', 'README.md']);
+      runGit(repo, ['commit', '-m', 'Initial commit']);
+
+      const hookLog = path.join(dataHome, 'post-checkout-failed.log');
+      installPostCheckoutHook(
+        repo,
+        `#!/bin/sh\nprintf 'ran' > ${JSON.stringify(hookLog)}\nexit 1\n`,
+      );
+
+      const created = await createWorktree(repo, {
+        mode: 'new',
+        worktreeName: 'hook-fail-test',
+        branchName: 'openchamber/hook-fail-test',
+        returnAfterDirectoryCreated: true,
+      });
+
+      await expect.poll(
+        async () => (await getWorktreeBootstrapStatus(created.path)).status,
+        { timeout: 5_000 },
+      ).toBe('ready');
+      expect(fs.readFileSync(hookLog, 'utf8')).toBe('ran');
+    } finally {
+      if (previousXdgDataHome === undefined) {
+        delete process.env.XDG_DATA_HOME;
+      } else {
+        process.env.XDG_DATA_HOME = previousXdgDataHome;
+      }
+    }
+  });
+
   it('waits for active bootstrap work before removing a worktree', async () => {
     if (!canRunGit()) return;