修复 Hook 链继承仓库定位变量导致真实仓库被夹具污染

- .husky/pre-commit 与 .husky/pre-push 入口清除 GIT_DIR/GIT_WORK_TREE/GIT_INDEX_FILE 等仓库定位变量

- scripts/check-repository-ci.sh 增加同样的清理，保证本地门禁与 CI 走同一套隔离

- scripts/git-hooks.test.mjs 夹具 Git 调用前自检仓库归属并禁用 Hook，命令落到外部仓库时直接失败

- 守卫用例的子进程必须真的继承 GIT_DIR，避免隔离断言空转

- 更新开发运维文档与 shared-memory/pitfalls.md，记录链接工作树注入形态与配置修复步骤

scripts/git-hooks.test.mjs

@@ -5,6 +5,7 @@ import {
   mkdirSync,
   mkdtempSync,
   readFileSync,
+  realpathSync,
   rmSync,
   symlinkSync,
   writeFileSync,
@@ -20,6 +21,8 @@ const packageJson = JSON.parse(
 );
 
 test('pre-commit hook fixes staged imports and formatting without swallowing unstaged work', () => {
+  assertGuardChildInheritsPoisonedEnvironment();
+
   assert.equal(packageJson.scripts.prepare, 'husky');
   assert.equal(packageJson.scripts['format:staged'], 'lint-staged');
   assert.deepEqual(packageJson['lint-staged'], {
@@ -29,9 +32,10 @@ test('pre-commit hook fixes staged imports and formatting without swallowing uns
     ],
     '*.rs': ['node scripts/lint-staged-rustfmt.mjs'],
   });
-  assert.equal(
+  assertHookClearsGitEnvironment(
+    'pre-commit',
     readFileSync(join(repoRoot, '.husky', 'pre-commit'), 'utf8'),
-    'npm run format:staged\n',
+    'npm run format:staged',
   );
 
   const tempRepo = createTempDirectory('genarrative-git-hooks-');
@@ -162,6 +166,8 @@ test('pre-commit hook fixes staged imports and formatting without swallowing uns
 });
 
 test('pre-push runs repository parity only for master updates', () => {
+  assertGuardChildInheritsPoisonedEnvironment();
+
   const tempDir = createTempDirectory('genarrative-pre-push-');
   try {
     const npmLog = join(tempDir, 'repo', 'npm.log');
@@ -291,10 +297,12 @@ test('hook fixtures do not mutate the calling linked worktree or its index', ()
         env: {
           ...isolatedGitEnvironment(),
           NODE_TEST_CONTEXT: undefined,
+          GENARRATIVE_HOOK_GUARD_CHILD: '1',
           GIT_DIR: gitDir,
           GIT_COMMON_DIR: join(outerRepo, '.git'),
           GIT_WORK_TREE: worktree,
           GIT_INDEX_FILE: indexPath,
+          GIT_PREFIX: '',
           GIT_CONFIG_COUNT: '1',
           GIT_CONFIG_KEY_0: 'core.worktree',
           GIT_CONFIG_VALUE_0: worktree,
@@ -353,7 +361,15 @@ test('Gitea Repository checks and master pre-push share the same repository comm
   );
   assert.match(repositoryScript, /npm run build/u);
   assert.match(repositoryScript, /git diff --check/u);
-  assert.equal(prePushHook, 'npm run check:pre-push-master -- "$@"\n');
+  assertHookClearsGitEnvironment(
+    'pre-push',
+    prePushHook,
+    'npm run check:pre-push-master -- "$@"',
+  );
+  assert.match(
+    repositoryScript,
+    /^unset GIT_DIR GIT_WORK_TREE GIT_INDEX_FILE GIT_COMMON_DIR/mu,
+  );
 });
 
 function readFileOrEmpty(path) {
@@ -376,11 +392,38 @@ function toBashPath(path) {
 }
 
 function git(cwd, ...args) {
-  return execFileSync('git', args, {
+  const env = isolatedGitEnvironment();
+  assertFixtureRepository(cwd, env);
+  return execFileSync(
+    'git',
+    ['--no-pager', '-c', `core.hooksPath=${nullDevice}`, ...args],
+    {
+      cwd,
+      encoding: 'utf8',
+      env,
+    },
+  );
+}
+
+// 夹具命令必须落在夹具自己的仓库：继承的 GIT_DIR/GIT_WORK_TREE 优先级高于 cwd，曾让夹具把
+// 身份、core.bare 与 core.worktree 写进调用方的真实仓库。
+function assertFixtureRepository(cwd, env) {
+  const probe = spawnSync('git', ['rev-parse', '--show-toplevel'], {
     cwd,
     encoding: 'utf8',
-    env: isolatedGitEnvironment(),
+    env,
   });
+  if (probe.status !== 0) {
+    // 此时夹具目录还不是仓库（例如首次 git init），命令本身会把它建起来。
+    return;
+  }
+  const toplevel = realpathSync.native(probe.stdout.trim());
+  const expected = realpathSync.native(resolve(cwd));
+  assert.equal(
+    toplevel,
+    expected,
+    `夹具 Git 命令会落到外部仓库：cwd=${expected} toplevel=${toplevel}`,
+  );
 }
 
 function isolatedGitEnvironment() {
@@ -391,6 +434,41 @@ function isolatedGitEnvironment() {
   );
 }
 
+// 守卫用例把本文件跑在毒化环境里；子进程必须真的继承 GIT_DIR，否则断言会空转。
+function assertGuardChildInheritsPoisonedEnvironment() {
+  if (process.env.GENARRATIVE_HOOK_GUARD_CHILD !== '1') {
+    return;
+  }
+  assert.ok(process.env.GIT_DIR, '守卫子进程必须继承 GIT_DIR');
+  assert.equal(
+    Object.hasOwn(isolatedGitEnvironment(), 'GIT_DIR'),
+    false,
+    '夹具子进程环境必须清除 GIT_DIR',
+  );
+}
+
+function assertHookClearsGitEnvironment(hookName, contents, command) {
+  const lines = contents.trimEnd().split('\n');
+  assert.equal(
+    lines.at(-1),
+    command,
+    `${hookName} 最后一行必须保持原有钩子命令`,
+  );
+  const unsetLine = lines.find((line) => line.startsWith('unset '));
+  assert.ok(unsetLine, `${hookName} 必须先清除 Git 注入的仓库定位变量`);
+  const cleared = new Set(unsetLine.split(/\s+/u));
+  for (const variable of [
+    'GIT_DIR',
+    'GIT_WORK_TREE',
+    'GIT_INDEX_FILE',
+    'GIT_COMMON_DIR',
+  ]) {
+    assert.ok(cleared.has(variable), `${hookName} 必须清除 ${variable}`);
+  }
+}
+
+const nullDevice = process.platform === 'win32' ? 'NUL' : '/dev/null';
+
 function createTempDirectory(prefix) {
   const tempRoot = join(homedir(), 'data', 'tmp');
   mkdirSync(tempRoot, { recursive: true });