From 3921e1b0b7c7282a8a8e9a450c3386b7f166c7d5 Mon Sep 17 00:00:00 2001
From: Peter Steinberger <steipete@gmail.com>
Date: Mon, 4 May 2026 14:07:54 +0100
Subject: [PATCH] fix(process): kill Windows command trees on timeout

(cherry picked from commit 9cc3ae100b846437dd3dcbcfaf20b242d9f6f6a2)
---
 src/process/exec.ts              | 11 +++++++++++
 src/process/exec.windows.test.ts | 31 +++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/src/process/exec.ts b/src/process/exec.ts
index c0ed7128900..6907b63cc2e 100644
--- a/src/process/exec.ts
+++ b/src/process/exec.ts
@@ -333,6 +333,17 @@ export async function runCommandWithTimeout(
         return;
       }
       killIssuedByTimeout = true;
+      if (process.platform === "win32" && typeof child.pid === "number" && child.pid > 0) {
+        try {
+          spawn("taskkill", ["/PID", String(child.pid), "/T", "/F"], {
+            stdio: "ignore",
+            windowsHide: true,
+          });
+          return;
+        } catch {
+          // Fall through to Node's direct child kill as a last resort.
+        }
+      }
       child.kill("SIGKILL");
     };
 
diff --git a/src/process/exec.windows.test.ts b/src/process/exec.windows.test.ts
index 66065bec8be..9be869c0bb8 100644
--- a/src/process/exec.windows.test.ts
+++ b/src/process/exec.windows.test.ts
@@ -370,6 +370,37 @@ describe("windows command wrapper behavior", () => {
     }
   });
 
+  it("kills the Windows process tree when the overall timeout elapses", async () => {
+    vi.useFakeTimers();
+    const platformSpy = vi.spyOn(process, "platform", "get").mockReturnValue("win32");
+    const child = createMockChild({ autoClose: false });
+    const taskkillChild = createMockChild();
+
+    spawnMock.mockImplementationOnce(() => child).mockImplementationOnce(() => taskkillChild);
+
+    try {
+      const resultPromise = runCommandWithTimeout(["node", "idle.js"], { timeoutMs: 80 });
+
+      await vi.advanceTimersByTimeAsync(81);
+      expect(child.kill).not.toHaveBeenCalled();
+      expect(spawnMock).toHaveBeenCalledTimes(2);
+      expect(spawnMock.mock.calls[1]?.[0]).toBe("taskkill");
+      expect(spawnMock.mock.calls[1]?.[1]).toEqual(["/PID", "1234", "/T", "/F"]);
+      expect(spawnMock.mock.calls[1]?.[2]).toMatchObject({
+        stdio: "ignore",
+        windowsHide: true,
+      });
+
+      child.emit("close", null, "SIGKILL");
+      const result = await resultPromise;
+      expect(result.termination).toBe("timeout");
+      expect(result.code).not.toBe(0);
+    } finally {
+      platformSpy.mockRestore();
+      vi.useRealTimers();
+    }
+  });
+
   it("decodes GBK stdout and stderr from runExec on Windows", async () => {
     const platformSpy = vi.spyOn(process, "platform", "get").mockReturnValue("win32");
     const stdout = Buffer.from([0xb2, 0xe2, 0xca, 0xd4]);