test: preserve ACP cleanup failures

examples/acp-agent/tests/cleanup.e2e.ts

@@ -0,0 +1,38 @@
+/** Regression coverage for ACP example teardown. */
+
+import { access, mkdtemp, rm } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { cleanupAcpExampleTest } from './cleanup.ts'
+
+let fallbackWorkdir: string | undefined
+
+afterEach(async () => {
+  if (fallbackWorkdir !== undefined) await rm(fallbackWorkdir, { recursive: true, force: true })
+  fallbackWorkdir = undefined
+})
+
+describe('cleanupAcpExampleTest', () => {
+  it('removes the workspace after process shutdown fails', async () => {
+    fallbackWorkdir = await mkdtemp(join(tmpdir(), 'acp-cleanup-'))
+    const closeFailure = new Error('close failed')
+    const spawned = { close: vi.fn().mockRejectedValue(closeFailure) }
+
+    await expect(cleanupAcpExampleTest(spawned, fallbackWorkdir))
+      .rejects.toMatchObject({ errors: [closeFailure] })
+    await expect(access(fallbackWorkdir)).rejects.toThrow()
+    fallbackWorkdir = undefined
+  })
+
+  it('reports process and workspace failures together', async () => {
+    const closeFailure = new Error('close failed')
+    const spawned = { close: vi.fn().mockRejectedValue(closeFailure) }
+
+    const failure = await cleanupAcpExampleTest(spawned, '\0').catch((error: unknown) => error)
+
+    expect(failure).toBeInstanceOf(AggregateError)
+    expect((failure as AggregateError).errors).toHaveLength(2)
+    expect((failure as AggregateError).errors[0]).toBe(closeFailure)
+  })
+})