fix(worker): ensure reconciled boxes before acquire

apps/agent-worker/tests/unit/user-container.test.ts

@@ -83,6 +83,30 @@ describe('box registry', () => {
     );
   });
 
+  test('ensures an adopted box once before returning acquire handles', async () => {
+    const module = await load();
+    const docker = await import('../../src/runtime/docker');
+    vi.mocked(docker.listWorkspaceContainerNames).mockResolvedValueOnce([
+      'spoon-box-casey',
+    ]);
+    await module.reconcileExistingBoxes();
+
+    const first = await module.acquireUserBox({
+      username: 'casey',
+      workdir: '/w',
+      containerHome: '/home/casey',
+    });
+    const second = await module.acquireUserBox({
+      username: 'casey',
+      workdir: '/w',
+      containerHome: '/home/casey',
+    });
+
+    expect(docker.ensureUserContainer).toHaveBeenCalledTimes(1);
+    expect(first.boxName).toBe('spoon-box-casey');
+    expect(second.boxName).toBe('spoon-box-casey');
+  });
+
   test('retries ensure after the first acquire fails', async () => {
     const module = await load();
     const docker = await import('../../src/runtime/docker');