fix(fs): S-10 hang test hook requires UMT_FS_TEST_HOOKS=1; preflight warns when set

Co-Authored-By: Claude Opus 5.5 <[email protected]>

packages/adapters/src/fs/fsproxy.ts

@@ -110,14 +110,19 @@ export function defaultWorkerCommand(): { cmd: string; args: string[]; kind: "sc
 /**
  * 仅容器/手工验收用:UMT_FS_TEST_HANG_AFTER_BYTES=<n> 让每个数据类操作的 worker 在读到 n 字节后卡死 JS 线程
  * (不响应 SIGTERM),用于在生产二进制里验证 停滞超时 → SIGKILL → TIMEOUT。只在子进程模式生效。
+ * 必须同时设置 UMT_FS_TEST_HOOKS=1 才生效(验收 07 S-10):单独误设这一个变量不会让所有文件操作卡死。
  */
+export function fsTestHookFromEnv(get: (k: string) => string | undefined): FsTestHook | undefined {
+  const v = get("UMT_FS_TEST_HANG_AFTER_BYTES");
+  if (v === undefined || v === "" || !/^\d+$/.test(v)) return undefined;
+  if (get("UMT_FS_TEST_HOOKS") !== "1") return undefined;
+  return { hangAfterBytes: Number(v), ignoreTerm: true };
+}
+
 function envTestHook(): FsTestHook | undefined {
   try {
-    const v = (globalThis as { Deno?: { env?: { get(k: string): string | undefined } } }).Deno?.env?.get(
-      "UMT_FS_TEST_HANG_AFTER_BYTES",
-    );
-    if (v === undefined || v === "" || !/^\d+$/.test(v)) return undefined;
-    return { hangAfterBytes: Number(v), ignoreTerm: true };
+    const env = (globalThis as { Deno?: { env?: { get(k: string): string | undefined } } }).Deno?.env;
+    return env ? fsTestHookFromEnv((k) => env.get(k)) : undefined;
   } catch {
     return undefined;
   }