fix: preserve executable lookup in isolated release validation

Author: rockyshi1993

changelogs/releases/v1.20.1.md

@@ -16,5 +16,6 @@
 - 记忆写入可根据真实宿主和唯一任务补齐会话编号及绑定，重复分配幂等；SUMMARY 支持结构化条目。
 - 更新后继续原任务；已发布版本、磁盘安装与当前宿主连接加载分别验证，不将安装成功宣称为已加载新运行时。
 - Windows 验证子进程等待父进程实际接收最终回执后再关闭通道，避免成功结果丢失而误记为中断。
+- 修复真实宿主安装验收的隔离环境丢失 `PATH`，并在耗时探针前检查 Codex 可执行文件及版本。
 
 这些恢复行为不覆盖宿主拒绝，不猜测冲突目标，不把保存草稿或未知副作用宣称为任务完成。

scripts/test-global-install-smoke.js

@@ -431,6 +431,7 @@ function isolatedHostEnv(home) {
   const resolvedHome = path.resolve(home)
   const parsedHome = path.parse(resolvedHome)
   return {
+    ...process.env,
     DEVCODEX_TEST_HOME: home,
     DEVCODEX_POSTINSTALL_FORCE: '1',
     CI: '',
@@ -677,6 +678,10 @@ assert.strictEqual(
 )
 
 const installedEnv = isolatedHostEnv(globalHome)
+// Resolve the real host using the same complete environment as direct helper calls,
+// before the expensive installed S15 probe starts.
+const realCodexExecutable = smokeOptions.realCodex ? resolveCodexExecutable(null, installedEnv) : null
+const realCodexVersion = smokeOptions.realCodex ? readCodexVersion(realCodexExecutable, installedEnv) : null
 runCommand(binPath, ['init', '--profile', 'consumer'], { cwd: workspace, env: installedEnv })
 assert.ok(fs.existsSync(path.join(workspace, '.devcodex')), 'workspace init must create only .devcodex runtime')
 assert.deepStrictEqual(
@@ -986,8 +991,6 @@ if (smokeOptions.realCodex) {
     'real-codex-host-probe.js'
   )
   assert.strictEqual(fs.existsSync(installedRealHostHelper), true, 'installed real-host helper is missing')
-  const realCodexExecutable = resolveCodexExecutable(null, installedEnv)
-  const realCodexVersion = readCodexVersion(realCodexExecutable, installedEnv)
   realHostIdentity = createRunIdentity({
     mode: 'installed',
     sourceCandidate: smokeOptions.sourceCandidate,