Restore the fresh recursive lstat in project inspectGit (Vikunja #780)

R1 passed the parent's stat of a listed directory into the recursive walk,
so a recursive entry no longer took its own lstat. A directory replaced by a
symlink after that stat passed the stale directory check and readdirSync
followed the link; a directory replaced by a regular file leaked a raw
ENOTDIR instead of refusing with project-repository.

The walk now takes a root flag. The .git root keeps its raw lstat and its
own error; every recursive entry takes a fresh lstat through statEntry, so
a vanished entry still maps ENOENT to 'git metadata changed during
inspection' and a replaced one refuses with 'expected local .git directory'.
The mapper is unchanged: ENOENT only.

Two deterministic tests replace a directory under .git/objects inside the
lstat call that stats it as a listed entry, after the real stat is taken:
once with a symlink to a fixture-only directory outside the repo, once with
a regular file. Both refuse with project-repository.

packages/project/src/git.mjs

@@ -24,17 +24,20 @@ export async function inspectGit(repo) {
     ? new ProjectError('project-repository', 'git metadata changed during inspection') : e;
   const statEntry = path => { try { return lstatSync(path); } catch (e) { throw changed(e); } };
   const namesIn = directory => { try { return readdirSync(directory); } catch (e) { throw changed(e); } };
-  // The root is not a listed name: a missing .git keeps its own error, as before.
-  const walk = (directory, st = lstatSync(directory)) => {
+  // Every directory takes a fresh lstat when the walk enters it, so one replaced by a link or a
+  // file after its listed stat still refuses. The root is not a listed name: a missing .git
+  // keeps its own error, as before.
+  const walk = (directory, root = false) => {
+    const st = root ? lstatSync(directory) : statEntry(directory);
     if (!st.isDirectory() || st.isSymbolicLink()) throw new ProjectError('project-repository', 'expected local .git directory');
     for (const name of namesIn(directory)) {
       const path = join(directory, name), entry = statEntry(path);
-      if (entry.isDirectory()) walk(path, entry);
+      if (entry.isDirectory()) walk(path);
       else if (!entry.isFile() || entry.nlink !== 1)
         throw new ProjectError('project-repository', 'git metadata must contain regular private files');
     }
   };
-  walk(join(repo, '.git'));
+  walk(join(repo, '.git'), true);
   for (const name of ['commondir', 'objects/info/alternates', 'objects/info/http-alternates']) {
     try { lstatSync(join(repo, '.git', name)); }
     catch (e) { if (e.code === 'ENOENT') continue; throw e; }

packages/project/tests/read.test.mjs

@@ -134,6 +134,45 @@ test('a git metadata entry that vanishes during inspection refuses as project-re
   assert.equal(git(repo, 'rev-parse', 'HEAD'), commit);
 });
 
+// Row 780 R2: the walk stats a listed directory, then must stat it again when it enters it. The
+// test replaces fs.lstatSync for one path and swaps the directory for something else inside the
+// call that stats it as a listed entry, after the real stat is taken. A walk that trusts that
+// stale stat would read through a link or leak ENOTDIR; the fresh stat refuses both.
+async function replaceListedDirectory(t, replace) {
+  const { context, repo, commit, root } = await fixture(t);
+  const directory = join(repo, '.git/objects/tmp_dir_replaced');
+  const outside = join(root, 'outside');
+  mkdirSync(directory); mkdirSync(outside); writeFileSync(join(outside, 'private'), 'x');
+  assert.equal((await api.readSpec(context)).commit, commit, 'control: the extra directory alone does not refuse');
+  const real = fs.lstatSync;
+  let armed = true;
+  fs.lstatSync = function (path, ...rest) {
+    if (!armed || String(path) !== directory) return real.call(this, path, ...rest);
+    armed = false;
+    const stat = real.call(this, path, ...rest);
+    fs.rmdirSync(directory); replace(directory, outside);
+    return stat;
+  };
+  syncBuiltinESMExports();
+  try {
+    await assert.rejects(api.readSpec(context), error => {
+      assert.equal(error.code, 'project-repository', error.message);
+      assert.match(error.message, /expected local \.git directory/);
+      return true;
+    });
+  } finally { fs.lstatSync = real; syncBuiltinESMExports(); }
+  assert.equal(armed, false, 'the listed directory was replaced during inspection');
+  assert.equal(git(repo, 'rev-parse', 'HEAD'), commit);
+}
+
+test('a git metadata directory replaced by a symlink after its listed stat refuses, never reads through it', async t => {
+  await replaceListedDirectory(t, (directory, outside) => symlinkSync(outside, directory));
+});
+
+test('a git metadata directory replaced by a file after its listed stat refuses, never raw ENOTDIR', async t => {
+  await replaceListedDirectory(t, directory => writeFileSync(directory, 'x'));
+});
+
 test('committed UTF-8 BOM, Unicode and trailing newlines are returned without normalization', async t => {
   const { context, save } = await fixture(t);
   const value = '\uFEFF# North star 🧭\r\n\r\n';