fix(subprocess): treat zombie-only groups as quiescent

packages/subprocess/subprocess-local/tests/process-inspector.spec.ts

@@ -1,5 +1,9 @@
 import { describe, expect, it } from 'vitest'
-import { createProcessInspector, parseProcStat } from '@deepseek-ai/dsh-subprocess-local/src/process-inspector.ts'
+import {
+  createProcessInspector,
+  linuxProcessGroupHasLiveMembers,
+  parseProcStat,
+} from '@deepseek-ai/dsh-subprocess-local/src/process-inspector.ts'
 import type { ProcessInspectorInternals } from '@deepseek-ai/dsh-subprocess-local/src/process-inspector.ts'
 
 function stat(pid: number, pgrp: number, session: number, tpgid: number, started: string, parentPid = 1, state = 'S'): string {
@@ -63,6 +67,21 @@ function fakeInternals() {
 }
 
 describe('Linux process inspector', () => {
+  it('treats zombie-only process groups as quiescent and fails closed when unobservable', () => {
+    const fake = fakeInternals()
+    expect(linuxProcessGroupHasLiveMembers(77, fake.internals)).toBeUndefined()
+
+    fake.dirs.set('/proc', ['self', '10', '11', '12'])
+    fake.files.set('/proc/10/stat', stat(10, 77, 10, -1, '500', 1, 'Z'))
+    fake.files.set('/proc/11/stat', stat(11, 77, 10, -1, '501', 1, 'X'))
+    fake.files.set('/proc/12/stat', stat(12, 88, 12, -1, '502'))
+    expect(linuxProcessGroupHasLiveMembers(77, fake.internals)).toBe(false)
+    expect(linuxProcessGroupHasLiveMembers(99, fake.internals)).toBeUndefined()
+
+    fake.files.set('/proc/11/stat', stat(11, 77, 10, -1, '501'))
+    expect(linuxProcessGroupHasLiveMembers(77, fake.internals)).toBe(true)
+  })
+
   it('parses stat safely, captures only the rooted process tree, and signals identities', () => {
     expect(parseProcStat('bad')).toBeUndefined()
     expect(parseProcStat('1 () ')).toBeUndefined()

packages/subprocess/subprocess-local/tests/spawn.spec.ts

@@ -268,6 +268,24 @@ describe('spawnSubprocess', () => {
     expect(result.signal).toBe('SIGTERM')
   })
 
+  it('does not wait for a Linux group that has only zombie members', async () => {
+    const pidFile = join(spillDir, `zombie-group-${Date.now()}.pid`)
+    let hasLiveMembers = false
+    const running = spawnSubprocess(spec(`sleep 60 & echo $! > ${pidFile}; echo leader-done`, { graceMs: 100 }), {
+      platform: 'linux',
+      linuxProcessGroupHasLiveMembers: () => hasLiveMembers,
+    })
+    const descendant = await waitForPidFile(pidFile)
+    try {
+      await running.done
+      await expect(running.waitForExit()).resolves.toBe(true)
+    } finally {
+      hasLiveMembers = true
+      running.terminate()
+      await waitGone(descendant)
+    }
+  })
+
   it('bounds inherited-pipe draining after the shell exits', async () => {
     const pidFile = join(spillDir, `pipe-holder-${Date.now()}.pid`)
     const started = Date.now()