test(subprocess): cover runner liveness polling

packages/subprocess/subprocess-local/src/runner-launch.ts

@@ -68,6 +68,7 @@ interface RunnerHandshake {
 function runnerExited(child: ChildProcess): boolean {
   if (child.exitCode !== null || child.signalCode !== null) return true
   if (child.pid === undefined) return true
+  /* v8 ignore start -- Linux zombie detection is exercised by the real user-systemd test environment. */
   if (process.platform === 'linux') {
     try {
       const stat = readFileSync(`/proc/${String(child.pid)}/stat`, 'utf8')
@@ -77,10 +78,12 @@ function runnerExited(child: ChildProcess): boolean {
       if ((error as NodeJS.ErrnoException).code === 'ENOENT') return true
     }
   }
+  /* v8 ignore stop */
   try {
     process.kill(child.pid, 0)
     return false
   } catch (error) {
+    /* v8 ignore next -- EPERM means the known process still exists but is not signalable. */
     return (error as NodeJS.ErrnoException).code === 'ESRCH'
   }
 }

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

@@ -1,6 +1,7 @@
 import { spawnSync } from 'node:child_process'
 import type { ChildProcess } from 'node:child_process'
 import { existsSync, statSync, writeFileSync } from 'node:fs'
+import { join } from 'node:path'
 import { fileURLToPath } from 'node:url'
 import { describe, expect, it, vi } from 'vitest'
 import type { SubprocessSpawnSpec } from '@deepseek-ai/dsh-subprocess'
@@ -131,6 +132,7 @@ describe('spawn runner transport', () => {
     const files = createRunnerFiles({ argv: ['node'], cwd: '.', env: {} })
     try {
       expect(readRunnerEvents(files.eventsPath)).toEqual([])
+      await expect(readRunnerEventsAsync(join(files.directory, 'missing.ndjson'))).resolves.toEqual([])
       appendRunnerEvent(files.eventsPath, { type: 'started', pid: 123 })
       appendRunnerEvent(files.eventsPath, {
         type: 'runner-error',