fix(bench): clean timed-out sample process groups

test/scripts/bench-cli-startup.test.ts

@@ -29,6 +29,15 @@ function withEnv<T>(env: Record<string, string | undefined>, callback: () => T):
   }
 }
 
+function isProcessAlive(pid: number): boolean {
+  try {
+    process.kill(pid, 0);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
 describe("bench-cli-startup", () => {
   it("rejects unknown CLI options before running benchmarks", () => {
     expect(() => testing.validateCliArgs(["--wat"])).toThrow("Unknown argument: --wat");
@@ -49,6 +58,71 @@ describe("bench-cli-startup", () => {
     expect(result.stderr).not.toContain("\n    at ");
   });
 
+  it.runIf(process.platform !== "win32")(
+    "cleans timed-out benchmark process groups when the leader exits first",
+    () => {
+      const tempDirs = createTempDirTracker();
+      const tmpDir = tempDirs.make("openclaw-cli-startup-timeout-group-");
+      const entryPath = join(tmpDir, "entry.mjs");
+      const childPidPath = join(tmpDir, "child.pid");
+      let childPid = 0;
+      try {
+        writeFileSync(
+          entryPath,
+          [
+            "import { spawn } from 'node:child_process';",
+            "import { writeFileSync } from 'node:fs';",
+            "process.on('SIGTERM', () => process.exit(0));",
+            "const child = spawn(process.execPath, [",
+            "  '-e',",
+            "  \"process.on('SIGTERM',()=>{});setInterval(()=>{},1000);\",",
+            "], { stdio: 'ignore' });",
+            `writeFileSync(${JSON.stringify(childPidPath)}, String(child.pid));`,
+            "setInterval(() => {}, 1000);",
+            "",
+          ].join("\n"),
+          "utf8",
+        );
+
+        const result = spawnSync(
+          process.execPath,
+          [
+            "--import",
+            "tsx",
+            "scripts/bench-cli-startup.ts",
+            "--entry",
+            entryPath,
+            "--case",
+            "version",
+            "--runs",
+            "1",
+            "--warmup",
+            "0",
+            "--timeout-ms",
+            "100",
+            "--json",
+          ],
+          {
+            cwd: join(__dirname, "../.."),
+            encoding: "utf8",
+            timeout: 8_000,
+          },
+        );
+
+        childPid = Number(readFileSync(childPidPath, "utf8"));
+        expect(result.status).toBe(1);
+        expect(result.signal).toBeNull();
+        expect(result.stderr).toContain("version sample 1: timed out");
+        expect(isProcessAlive(childPid)).toBe(false);
+      } finally {
+        if (childPid && isProcessAlive(childPid)) {
+          process.kill(childPid, "SIGKILL");
+        }
+        tempDirs.cleanup();
+      }
+    },
+  );
+
   it("writes compare-mode JSON output and creates parent directories", () => {
     const tempDirs = createTempDirTracker();
     const tmpDir = tempDirs.make("openclaw-cli-startup-compare-output-");