fix(worker): ensure reconciled boxes before acquire

apps/agent-worker/src/user-container.ts

@@ -13,6 +13,7 @@ export type BoxHandle = { boxName: string; release: () => void };
 
 type Box = {
   name: string;
+  initialized: boolean;
   refs: Set<symbol>;
   idleTimer?: ReturnType<typeof setTimeout>;
 };
@@ -71,21 +72,26 @@ export const acquireUserBox = (args: {
 }): Promise<BoxHandle> =>
   withLock(args.username, async () => {
     let box = boxes.get(args.username);
-    let needsEnsure = false;
     if (box?.idleTimer) {
       clearTimeout(box.idleTimer);
       box.idleTimer = undefined;
     }
     if (!box) {
-      box = { name: userContainerName(args.username), refs: new Set() };
+      box = {
+        name: userContainerName(args.username),
+        initialized: false,
+        refs: new Set(),
+      };
       boxes.set(args.username, box);
-      needsEnsure = true;
     }
     // Register the ref before the slow Docker call so a failed acquire can
     // release it without leaking registry state.
     const handle = makeHandle(args.username, box);
     try {
-      if (needsEnsure) box.name = await ensureUserContainer(args);
+      if (!box.initialized) {
+        box.name = await ensureUserContainer(args);
+        box.initialized = true;
+      }
       return handle;
     } catch (error) {
       handle.release();
@@ -103,7 +109,7 @@ export const reconcileExistingBoxes = async (): Promise<void> => {
   for (const name of names) {
     const username = name.replace(/^spoon-box-/, '');
     if (boxes.has(username)) continue;
-    const box: Box = { name, refs: new Set() };
+    const box: Box = { name, initialized: false, refs: new Set() };
     boxes.set(username, box);
     scheduleReapIfIdle(username);
   }

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');