diff --git a/extensions/qa-matrix/src/runners/contract/scenario-runtime-cli.test.ts b/extensions/qa-matrix/src/runners/contract/scenario-runtime-cli.test.ts
index 727d720720bf..38e89d967b7d 100644
--- a/extensions/qa-matrix/src/runners/contract/scenario-runtime-cli.test.ts
+++ b/extensions/qa-matrix/src/runners/contract/scenario-runtime-cli.test.ts
@@ -21,6 +21,19 @@ function isProcessRunning(pid: number): boolean {
   }
 }
 
+async function waitForFile(pathToCheck: string, timeoutMs: number): Promise<void> {
+  const deadline = Date.now() + timeoutMs;
+  while (Date.now() < deadline) {
+    try {
+      await readFile(pathToCheck, "utf8");
+      return;
+    } catch {
+      await sleep(25);
+    }
+  }
+  throw new Error(`Timed out waiting for ${pathToCheck}`);
+}
+
 describe("Matrix QA CLI runtime", () => {
   it("redacts secret CLI arguments in diagnostic command text", () => {
     expect(
@@ -314,4 +327,55 @@ describe("Matrix QA CLI runtime", () => {
       await rm(root, { force: true, recursive: true });
     }
   });
+
+  it("kills ignored-stdio descendants after a timed-out CLI exits gracefully", async () => {
+    if (process.platform === "win32") {
+      return;
+    }
+    const root = await mkdtemp(
+      path.join(resolvePreferredOpenClawTmpDir(), "matrix-qa-cli-timeout-ignored-stdio-"),
+    );
+    const childPidPath = path.join(root, "child.pid");
+    const grandchildPidPath = path.join(root, "grandchild.pid");
+    let childPid: number | undefined;
+    let grandchildPid: number | undefined;
+    try {
+      await mkdir(path.join(root, "dist"));
+      await writeFile(
+        path.join(root, "dist", "index.mjs"),
+        [
+          "import { spawn } from 'node:child_process';",
+          "import { writeFileSync } from 'node:fs';",
+          `writeFileSync(${JSON.stringify(childPidPath)}, String(process.pid));`,
+          "const grandchild = spawn(process.execPath, ['-e', 'process.on(\\'SIGTERM\\', () => {}); setInterval(() => {}, 1000);'], { stdio: 'ignore' });",
+          "grandchild.unref();",
+          `writeFileSync(${JSON.stringify(grandchildPidPath)}, String(grandchild.pid));`,
+          "process.on('SIGTERM', () => process.exit(0));",
+          "setInterval(() => {}, 1000);",
+        ].join("\n"),
+      );
+
+      const run = runMatrixQaOpenClawCli({
+        args: ["matrix", "verify", "self"],
+        cwd: root,
+        env: process.env,
+        timeoutMs: 500,
+      });
+      await waitForFile(grandchildPidPath, 2_000);
+
+      await expect(run).rejects.toThrow(/timed out after 500ms/u);
+
+      childPid = Number(await readFile(childPidPath, "utf8"));
+      grandchildPid = Number(await readFile(grandchildPidPath, "utf8"));
+      expect(isProcessRunning(childPid)).toBe(false);
+      expect(isProcessRunning(grandchildPid)).toBe(false);
+    } finally {
+      for (const pid of [grandchildPid, childPid]) {
+        if (pid && isProcessRunning(pid)) {
+          process.kill(pid, "SIGKILL");
+        }
+      }
+      await rm(root, { force: true, recursive: true });
+    }
+  });
 });
diff --git a/extensions/qa-matrix/src/runners/contract/scenario-runtime-cli.ts b/extensions/qa-matrix/src/runners/contract/scenario-runtime-cli.ts
index a6bc399963f3..929078e2ca21 100644
--- a/extensions/qa-matrix/src/runners/contract/scenario-runtime-cli.ts
+++ b/extensions/qa-matrix/src/runners/contract/scenario-runtime-cli.ts
@@ -119,6 +119,20 @@ function killMatrixQaCliChild(
   child.kill(signal);
 }
 
+function isMatrixQaCliChildProcessGroupRunning(
+  child: ReturnType<typeof startOpenClawCliProcess>,
+): boolean {
+  if (process.platform === "win32" || !child.pid) {
+    return false;
+  }
+  try {
+    process.kill(-child.pid, 0);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
 export function startMatrixQaOpenClawCli(params: {
   allowNonZero?: boolean;
   args: string[];
@@ -170,22 +184,36 @@ export function startMatrixQaOpenClawCli(params: {
       settleWait.resolve(result);
     }
   };
+  const finishTimeout = (result: MatrixQaCliRunResult) => {
+    finish(result, new Error(formatMatrixQaCliTimeoutError(result, params.timeoutMs)));
+  };
+  const clearForcedTimeouts = () => {
+    if (forceKillTimeout) {
+      clearTimeout(forceKillTimeout);
+      forceKillTimeout = undefined;
+    }
+    if (forceSettleTimeout) {
+      clearTimeout(forceSettleTimeout);
+      forceSettleTimeout = undefined;
+    }
+  };
 
   const timeout = setTimeout(() => {
     timedOut = true;
     killMatrixQaCliChild(child, "SIGTERM");
     forceKillTimeout = setTimeout(() => {
-      if (!closed) {
-        killMatrixQaCliChild(child, "SIGKILL");
-        forceSettleTimeout = setTimeout(() => {
-          const result = buildMatrixQaCliResult({
+      forceKillTimeout = undefined;
+      killMatrixQaCliChild(child, "SIGKILL");
+      forceSettleTimeout = setTimeout(() => {
+        forceSettleTimeout = undefined;
+        finishTimeout(
+          buildMatrixQaCliResult({
             args: params.args,
             exitCode: 1,
             output: readOutput(),
-          });
-          finish(result, new Error(formatMatrixQaCliTimeoutError(result, params.timeoutMs)));
-        }, MATRIX_QA_CLI_TIMEOUT_FORCE_SETTLE_MS);
-      }
+          }),
+        );
+      }, MATRIX_QA_CLI_TIMEOUT_FORCE_SETTLE_MS);
     }, MATRIX_QA_CLI_TIMEOUT_KILL_GRACE_MS);
   }, params.timeoutMs);
 
@@ -196,12 +224,7 @@ export function startMatrixQaOpenClawCli(params: {
   }
   child.on("error", (error) => {
     clearTimeout(timeout);
-    if (forceKillTimeout) {
-      clearTimeout(forceKillTimeout);
-    }
-    if (forceSettleTimeout) {
-      clearTimeout(forceSettleTimeout);
-    }
+    clearForcedTimeouts();
     finish(
       buildMatrixQaCliResult({
         args: params.args,
@@ -213,21 +236,20 @@ export function startMatrixQaOpenClawCli(params: {
   });
   child.on("close", (exitCode) => {
     clearTimeout(timeout);
-    if (forceKillTimeout) {
-      clearTimeout(forceKillTimeout);
-    }
-    if (forceSettleTimeout) {
-      clearTimeout(forceSettleTimeout);
-    }
     const result = buildMatrixQaCliResult({
       args: params.args,
       exitCode: exitCode ?? 1,
       output: readOutput(),
     });
     if (timedOut) {
-      finish(result, new Error(formatMatrixQaCliTimeoutError(result, params.timeoutMs)));
+      if (isMatrixQaCliChildProcessGroupRunning(child)) {
+        return;
+      }
+      clearForcedTimeouts();
+      finishTimeout(result);
       return;
     }
+    clearForcedTimeouts();
     if (result.exitCode !== 0 && params.allowNonZero !== true) {
       finish(result, new Error(formatMatrixQaCliExitError(result)));
       return;