diff --git a/AGENTS.md b/AGENTS.md
index 2a3a0bed0..0250a4b74 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -106,6 +106,19 @@ When editing the framework monorepo (this repo, not a scaffolded app): **`packag
 
 See `agent-docs/framework-dev.md` for monorepo commands, workspace layout, reference codebases, and per-feature update checklists.
 
+### Repo health: worktree-safe git config (core.bare / hooksPath)
+
+This repo uses git worktrees (the review subagents spawn throwaway ones under `.claude/worktrees/`). Git's worktree machinery can leave `core.bare=true` in the shared `.git/config`, which is lethal to the main checkout: every git operation that needs a work tree then fails with `fatal: this operation must be run in a work tree`. The shared value is harmless only while the main worktree carries a per-worktree override (`extensions.worktreeConfig=true` plus a `.git/config.worktree` pinning `core.bare=false`).
+
+`scripts/git-worktree-safe.mjs` establishes that override and pins an absolute `core.hooksPath` to `.hooks` on the main worktree, where both survive a shared-config reset (which is what otherwise silently disables the framework `.hooks/pre-commit`). It runs from the root `prepare` script, so every `npm install` self-heals. Two manual entry points:
+
+- `npm run fix:git` heals the config on demand (run it if a git command reports the work-tree error).
+- `npm run check:git` asserts the invariant (`core.bare` resolves false, the framework hook is active) and exits non-zero otherwise. The regression test is `test/repo-health/git-worktree-safe.test.mjs`.
+
+Because the pin lives in the main worktree's `config.worktree`, `git worktree add` copies it into each linked worktree, so a commit made inside a throwaway review worktree also runs the framework `.hooks/pre-commit`. That is harmless (the hook only blocks main and auto-generates a changelog on a version bump), and review subagents are read-only so they do not commit; the inheritance is noted here only so the behavior is not surprising.
+
+The fix only repairs the LOCAL checkout. Commits and branches are always safe on GitHub regardless.
+
 ### Changelog: per-package, per-version, auto-generated
 
 webjs ships per-package per-version changelogs under `changelog/<pkg>/<version>.md`. The model: **a version bump is the trigger**. When any commit on `main` changes the `version` field in `packages/<pkg>/package.json`, the scripts/backfill-changelog.js generator emits a new `changelog/<pkg>/<version>.md` summarising every conventional-commit (`feat:` / `fix:` / `breaking:` / `perf:`) that landed in that package since the prior bump. The website renders the union of all packages' files at `/changelog`.
diff --git a/package.json b/package.json
index 5ae551f0f..5cced9516 100644
--- a/package.json
+++ b/package.json
@@ -16,7 +16,9 @@
     "node": ">=24.0.0"
   },
   "scripts": {
-    "prepare": "git config core.hooksPath .hooks 2>/dev/null || true",
+    "prepare": "node scripts/git-worktree-safe.mjs",
+    "fix:git": "node scripts/git-worktree-safe.mjs",
+    "check:git": "node scripts/git-worktree-safe.mjs --check",
     "dev": "node scripts/dev-all.js",
     "test": "node scripts/run-node-tests.js",
     "test:browser": "wtr",
diff --git a/scripts/git-worktree-safe.mjs b/scripts/git-worktree-safe.mjs
new file mode 100644
index 000000000..42c8369ec
--- /dev/null
+++ b/scripts/git-worktree-safe.mjs
@@ -0,0 +1,156 @@
+#!/usr/bin/env node
+// Keeps the main checkout safe from the recurring core.bare=true corruption
+// (issue #166) and the related core.hooksPath reset.
+//
+// Background. This repo uses git worktrees (the review subagents spawn
+// throwaway worktrees under .claude/worktrees/). With git's worktree
+// machinery, the shared .git/config can end up carrying core.bare=true.
+// The shared value is harmless ONLY while the main worktree has a
+// per-worktree override (extensions.worktreeConfig=true plus a
+// .git/config.worktree pinning core.bare=false). If that override is
+// missing, the main checkout reads the shared core.bare=true and every
+// git operation that needs a work tree fails with
+// "fatal: this operation must be run in a work tree".
+//
+// Separately, the old `prepare` wrote a RELATIVE core.hooksPath (.hooks)
+// to the SHARED config. A relative hooksPath is resolved at read time and
+// the shared surface is the same one worktree events reset, which is how
+// the framework hook (.hooks/pre-commit) silently stops firing and the
+// absolute default .git/hooks takes over.
+//
+// This script pins both values on the MAIN worktree (where they survive a
+// shared-config reset) and is idempotent, so `prepare` can run it on every
+// `npm install` as a self-heal. Nothing here is ever lost on GitHub; this
+// only repairs the LOCAL checkout.
+//
+// Usage:
+//   node scripts/git-worktree-safe.mjs            ensure/heal (default)
+//   node scripts/git-worktree-safe.mjs --check    assert the invariant; exit 1 if violated
+
+import { execFileSync } from 'node:child_process';
+import { existsSync } from 'node:fs';
+import { join, resolve, isAbsolute } from 'node:path';
+
+const CHECK = process.argv.includes('--check');
+
+function git(args, { allowFail = false } = {}) {
+  try {
+    return execFileSync('git', args, {
+      encoding: 'utf8',
+      stdio: ['ignore', 'pipe', 'ignore'],
+    }).trim();
+  } catch (err) {
+    if (allowFail) return null;
+    throw err;
+  }
+}
+
+function isInsideWorkTree() {
+  return git(['rev-parse', '--is-inside-work-tree'], { allowFail: true }) === 'true';
+}
+
+// Resolve the work-tree root. When the repo is in the corrupted bare state
+// `--show-toplevel` fails, so fall back to the common dir's parent.
+function topLevel() {
+  const top = git(['rev-parse', '--show-toplevel'], { allowFail: true });
+  if (top) return top;
+  const commonDir = git(['rev-parse', '--git-common-dir'], { allowFail: true });
+  if (commonDir) return resolve(commonDir, '..');
+  return process.cwd();
+}
+
+function ensure() {
+  // 1. Un-break the shared value first so the rest of the commands (which
+  //    need a work tree) succeed even if we started corrupted.
+  git(['config', '--local', 'core.bare', 'false'], { allowFail: true });
+
+  // 2. Enable per-worktree config and pin the override on the MAIN worktree.
+  //    The override wins even if a later worktree event flips the shared
+  //    core.bare back to true. extensions.* are only contractually honored at
+  //    core.repositoryformatversion >= 1, and git's own `git worktree` bumps
+  //    it when enabling worktreeConfig; match that so a stricter git cannot
+  //    silently ignore the override the fix depends on.
+  git(['config', 'core.repositoryformatversion', '1'], { allowFail: true });
+  git(['config', 'extensions.worktreeConfig', 'true'], { allowFail: true });
+  git(['config', '--worktree', 'core.bare', 'false'], { allowFail: true });
+
+  // 3. Pin core.hooksPath to an ABSOLUTE path on the main worktree so it is
+  //    cwd-independent and survives a shared-config reset. Only when the
+  //    tracked .hooks dir exists (the framework repo); a generic repo using
+  //    this script keeps its own hooks.
+  const top = topLevel();
+  const hooksDir = join(top, '.hooks');
+  let hooksMsg = 'core.hooksPath: left as-is (.hooks not present)';
+  if (existsSync(hooksDir)) {
+    git(['config', '--worktree', 'core.hooksPath', hooksDir], { allowFail: true });
+    hooksMsg = `core.hooksPath: ${hooksDir}`;
+  }
+
+  const resolvedBare = git(['config', 'core.bare'], { allowFail: true });
+  console.log('[git-worktree-safe] ensured worktree-safe config:');
+  console.log(`  extensions.worktreeConfig: ${git(['config', 'extensions.worktreeConfig'], { allowFail: true })}`);
+  console.log(`  core.bare (resolved): ${resolvedBare}`);
+  console.log(`  ${hooksMsg}`);
+}
+
+function check() {
+  const problems = [];
+
+  if (!isInsideWorkTree()) {
+    problems.push('repo is not a usable work tree (core.bare resolves true); run: npm run fix:git');
+  } else {
+    const resolvedBare = git(['config', 'core.bare'], { allowFail: true });
+    if (resolvedBare !== 'false') {
+      problems.push(`core.bare resolves to "${resolvedBare}" (expected "false")`);
+    }
+  }
+
+  const wtConfig = git(['config', 'extensions.worktreeConfig'], { allowFail: true });
+  if (wtConfig !== 'true') {
+    problems.push(`extensions.worktreeConfig is "${wtConfig}" (expected "true"); without it a shared core.bare flip is fatal`);
+  }
+
+  // extensions.worktreeConfig is only contractually honored at rfv >= 1, so a
+  // drop back to 0 is the same threat as worktreeConfig being off: assert it
+  // here, not just in ensure, or the guard does not defend the property.
+  const rfv = parseInt(git(['config', 'core.repositoryformatversion'], { allowFail: true }) || '0', 10);
+  if (!(rfv >= 1)) {
+    problems.push(`core.repositoryformatversion is "${rfv}" (expected >= 1); below it a stricter git may ignore the worktree override`);
+  }
+
+  const top = topLevel();
+  const hooksDir = join(top, '.hooks');
+  if (existsSync(hooksDir)) {
+    const resolvedHooks = git(['config', 'core.hooksPath'], { allowFail: true });
+    // Compare WITHOUT resolving a relative value against the cwd. The old
+    // drift was a relative `.hooks` on the shared config, which a cwd-relative
+    // resolve() would pass from the repo root but fail from a subdirectory.
+    // ensure pins an absolute path, so a healthy repo is an exact match and a
+    // relative value fails the same way regardless of where the check runs.
+    const hooksOk = resolvedHooks && isAbsolute(resolvedHooks)
+      && resolve(resolvedHooks) === resolve(hooksDir);
+    if (!hooksOk) {
+      problems.push(`core.hooksPath is "${resolvedHooks}" (expected the absolute "${hooksDir}"); the framework hook is not reliably active`);
+    }
+  }
+
+  if (problems.length) {
+    console.error('[git-worktree-safe] repo health check FAILED:');
+    for (const p of problems) console.error(`  - ${p}`);
+    console.error('Fix with: npm run fix:git');
+    process.exit(1);
+  }
+  console.log('[git-worktree-safe] repo health check passed (core.bare=false, hooks active).');
+}
+
+try {
+  if (CHECK) check();
+  else ensure();
+} catch (err) {
+  // Ensure mode must never fail `npm install`. Surface the reason and exit 0.
+  if (!CHECK) {
+    console.warn(`[git-worktree-safe] could not fully ensure config: ${String(err.message).split('\n')[0]}`);
+    process.exit(0);
+  }
+  throw err;
+}
diff --git a/test/repo-health/git-worktree-safe.test.mjs b/test/repo-health/git-worktree-safe.test.mjs
new file mode 100644
index 000000000..f0cd190cd
--- /dev/null
+++ b/test/repo-health/git-worktree-safe.test.mjs
@@ -0,0 +1,133 @@
+// Regression guard for issue #166 (recurring core.bare=true corruption).
+//
+// Proves scripts/git-worktree-safe.mjs heals a repo that is in the broken
+// bare state, that --check catches the breakage, and that the per-worktree
+// override survives a later shared-config core.bare flip (the exact event
+// that used to re-break the main checkout).
+
+import { test, describe, before, after } from 'node:test';
+import assert from 'node:assert/strict';
+import { execFileSync } from 'node:child_process';
+import { mkdtempSync, mkdirSync, writeFileSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join, dirname } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const SCRIPT = join(
+  dirname(fileURLToPath(import.meta.url)),
+  '..', '..', 'scripts', 'git-worktree-safe.mjs',
+);
+
+let repo;
+
+function git(args, opts = {}) {
+  return execFileSync('git', args, { cwd: repo, encoding: 'utf8', ...opts }).trim();
+}
+// Run the heal/check script in the throwaway repo. Returns {code, out}.
+function runScript(args = []) {
+  try {
+    const out = execFileSync(process.execPath, [SCRIPT, ...args], {
+      cwd: repo, encoding: 'utf8', stdio: ['ignore', 'pipe', 'pipe'],
+    });
+    return { code: 0, out };
+  } catch (err) {
+    return { code: err.status ?? 1, out: `${err.stdout ?? ''}${err.stderr ?? ''}` };
+  }
+}
+
+before(() => {
+  repo = mkdtempSync(join(tmpdir(), 'webjs-corebare-'));
+  git(['init', '-q']);
+  git(['config', 'user.email', 't@t.t']);
+  git(['config', 'user.name', 't']);
+  writeFileSync(join(repo, 'a.txt'), 'hi\n');
+  git(['add', 'a.txt']);
+  git(['commit', '-qm', 'init']);
+  // A tracked .hooks dir so the script exercises the hooksPath branch.
+  mkdirSync(join(repo, '.hooks'));
+  writeFileSync(join(repo, '.hooks', 'pre-commit'), '#!/bin/bash\nexit 0\n');
+});
+
+after(() => {
+  if (repo) rmSync(repo, { recursive: true, force: true });
+});
+
+describe('git-worktree-safe (#166)', () => {
+  test('--check fails when the shared config is in the broken bare state', () => {
+    // Simulate the corruption: shared core.bare=true, no per-worktree override.
+    git(['config', '--local', 'core.bare', 'true']);
+    assert.notEqual(
+      git(['rev-parse', '--is-inside-work-tree'], { stdio: ['ignore', 'pipe', 'ignore'] }, ),
+      'true',
+      'precondition: the repo should read as bare/broken',
+    );
+    const { code } = runScript(['--check']);
+    assert.equal(code, 1, '--check must exit non-zero on the broken state');
+  });
+
+  test('ensure heals the broken state', () => {
+    const { code } = runScript();
+    assert.equal(code, 0, 'ensure must succeed');
+    assert.equal(git(['rev-parse', '--is-inside-work-tree']), 'true',
+      'main checkout is a usable work tree again');
+    assert.equal(git(['config', 'core.bare']), 'false',
+      'core.bare resolves to false');
+    assert.equal(git(['config', 'extensions.worktreeConfig']), 'true',
+      'per-worktree config is enabled');
+    assert.equal(git(['config', 'core.repositoryformatversion']), '1',
+      'repositoryformatversion bumped to 1 so the extension is contractually honored');
+    const hooks = git(['config', 'core.hooksPath']);
+    assert.equal(hooks, join(repo, '.hooks'),
+      'core.hooksPath pinned to the absolute .hooks dir');
+  });
+
+  test('--check passes after healing', () => {
+    assert.equal(runScript(['--check']).code, 0);
+  });
+
+  test('the per-worktree override survives a later SHARED core.bare flip', () => {
+    // This is the event that used to re-break the checkout every time.
+    git(['config', '--local', 'core.bare', 'true']);
+    assert.equal(git(['config', 'core.bare']), 'false',
+      'main worktree still reads false despite the shared flip');
+    assert.equal(git(['rev-parse', '--is-inside-work-tree']), 'true');
+    assert.equal(runScript(['--check']).code, 0,
+      '--check stays green because the override holds');
+  });
+
+  test('ensure is idempotent', () => {
+    assert.equal(runScript().code, 0);
+    assert.equal(runScript().code, 0);
+    assert.equal(runScript(['--check']).code, 0);
+  });
+
+  test('--check rejects a relative hooksPath drift, cwd-independently', () => {
+    // Drift hooksPath back to a relative value (the old-prepare bug), while
+    // core.bare and worktreeConfig stay healthy. A cwd-relative comparison
+    // would have passed this from the repo root; it must fail everywhere.
+    git(['config', '--worktree', 'core.hooksPath', '.hooks']);
+    assert.equal(runScript(['--check']).code, 1, 'fails from the repo root');
+    const sub = join(repo, 'pkg', 'nested');
+    mkdirSync(sub, { recursive: true });
+    let fromSub;
+    try {
+      execFileSync(process.execPath, [SCRIPT, '--check'], { cwd: sub, stdio: ['ignore', 'pipe', 'pipe'] });
+      fromSub = 0;
+    } catch (err) { fromSub = err.status ?? 1; }
+    assert.equal(fromSub, 1, 'fails from a subdirectory too');
+    // Healing restores the absolute pin and the check goes green.
+    assert.equal(runScript().code, 0);
+    assert.equal(runScript(['--check']).code, 0);
+  });
+
+  test('--check rejects an rfv drop below 1 (worktree override no longer guaranteed)', () => {
+    // worktreeConfig + the override stay in place; only rfv drops. Current git
+    // still honors the override, but the check must flag it because a stricter
+    // git would not, which is exactly what ensure's rfv bump defends against.
+    git(['config', 'core.repositoryformatversion', '0']);
+    assert.equal(runScript(['--check']).code, 1, 'rfv < 1 must fail the check');
+    assert.equal(runScript().code, 0);
+    assert.equal(git(['config', 'core.repositoryformatversion']), '1', 'heal restores rfv=1');
+    assert.equal(runScript(['--check']).code, 0);
+  });
+});