From b1b076f99333046ad4c6751dc031552d63056b78 Mon Sep 17 00:00:00 2001
From: Tianyi Cui <53024+tianyicui@users.noreply.github.com>
Date: Sun, 19 Jul 2026 13:49:48 +0800
Subject: [PATCH] test(acp-snapshot): cover accepted fallback termination

Drive the shutdown path where the requested signal reports a child error without exiting, the bounded marker grace expires, and fallback SIGKILL is accepted.

Assert that both signals are attempted and that close drains the successful fallback exit before preserving the original child error, restoring per-file 100% branch and line coverage for the launcher.
---
 .../acp-snapshot/tests/harness.spec.ts        | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/packages/support/acp-snapshot/tests/harness.spec.ts b/packages/support/acp-snapshot/tests/harness.spec.ts
index 5d12b2da97..64076c1217 100644
--- a/packages/support/acp-snapshot/tests/harness.spec.ts
+++ b/packages/support/acp-snapshot/tests/harness.spec.ts
@@ -248,6 +248,28 @@ describe('runScenario', () => {
     }
   })
 
+  it('preserves the child error after accepted fallback termination drains', async () => {
+    const { dir } = await scenario({})
+    const launched = launchAcpTestAgent({ agent: AGENT, cwd: dir })
+    await launched.spawned
+
+    const childFailure = Object.assign(new Error('requested signal failed before fallback'), { code: 'EPERM' })
+    const originalKill = launched.child.kill.bind(launched.child)
+    const kill = vi.spyOn(launched.child, 'kill').mockImplementation((signal) => {
+      if (signal === 'SIGTERM') return true
+      return originalKill('SIGKILL')
+    })
+    try {
+      launched.child.emit('error', childFailure)
+      await expect(launched.close('SIGTERM')).rejects.toBe(childFailure)
+      expect(kill).toHaveBeenNthCalledWith(1, 'SIGTERM')
+      expect(kill).toHaveBeenNthCalledWith(2, 'SIGKILL')
+    } finally {
+      kill.mockRestore()
+      if (launched.child.exitCode === null && launched.child.signalCode === null) originalKill('SIGKILL')
+    }
+  })
+
   it('rejects promptly when fallback termination emits an error', async () => {
     const { dir } = await scenario({})
     const launched = launchAcpTestAgent({ agent: AGENT, cwd: dir })