test(files): cover the review's two remaining outside-worktree cases

The symlinked .git folder test now also runs from a session in the main
checkout, as well as from a linked worktree. A new pane-watcher test
checks that an unparseable docker-cases.json follows nothing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/live-worktree-outside.test.ts

@@ -157,7 +157,9 @@ describe('findLiveWorktree outside the session folder', () => {
     const fake = join(base, 'fake');
     mkdirSync(fake);
     symlinkSync(join(repo, '.git'), join(fake, '.git'));
-    // The session is in the linked worktree, so the main-worktree branch is the one exercised.
+    // From a session in the main checkout.
+    expect(await findLiveWorktree(repo, fake, { home })).toBeUndefined();
+    // From a session in a linked worktree.
     expect(await findLiveWorktree(sibling, fake, { home })).toBeUndefined();
     // The real main worktree is still followed from the same session.
     expect(await findLiveWorktree(sibling, repo, { home })).toEqual({ name: 'myapp', path: repo, outside: true });

test/pane-cwd-tracking.test.ts

@@ -491,6 +491,20 @@ describe('a pane read reaching the session record', () => {
       }
     });
 
+    it('follows nothing while docker-cases.json cannot be parsed', async () => {
+      const casesFile = dataPath('docker-cases.json');
+      mkdirSync(dirname(casesFile), { recursive: true });
+      try {
+        // A read that lands while the writer is rewriting the file.
+        writeFileSync(casesFile, '[{"hostWorkspacePath": "/hom');
+        expect(await paneInSibling()).toBeUndefined();
+        writeFileSync(casesFile, '[]');
+        expect(await paneInSibling()).toEqual({ name: 'myapp-feature', path: sibling, outside: true });
+      } finally {
+        rmSync(casesFile, { force: true });
+      }
+    });
+
     it('applies the owner folder rule in multi-user mode', async () => {
       const spaces = join(base, 'spaces');
       mkdirSync(spaces);