fix(scripts): kill boundary prep trees on windows

test/scripts/prepare-extension-package-boundary-artifacts.test.ts

@@ -7,7 +7,7 @@ import os from "node:os";
 import path from "node:path";
 import { setTimeout as delay } from "node:timers/promises";
 import { pathToFileURL } from "node:url";
-import { afterEach, describe, expect, it } from "vitest";
+import { afterEach, describe, expect, it, vi } from "vitest";
 import {
   createPrefixedOutputWriter,
   isArtifactSetFresh,
@@ -17,6 +17,7 @@ import {
   runNodeStep,
   runNodeSteps,
   runNodeStepsInParallel,
+  signalNodeStep,
 } from "../../scripts/prepare-extension-package-boundary-artifacts.mjs";
 import { makeTempDir } from "../helpers/temp-dir.js";
 
@@ -123,6 +124,31 @@ describe("prepare-extension-package-boundary-artifacts", () => {
     expect(Date.now() - startedAt).toBeLessThan(abortBudgetMs);
   }, 45_000);
 
+  it("signals Windows node step process trees with taskkill", () => {
+    const child = {
+      kill: vi.fn(),
+      pid: 12345,
+    };
+    const runTaskkill = vi.fn(() => ({ error: undefined, status: 0 }));
+
+    signalNodeStep(child, "SIGTERM", {
+      platform: "win32",
+      runTaskkill,
+    });
+    expect(runTaskkill).toHaveBeenNthCalledWith(1, "taskkill", ["/PID", "12345", "/T"], {
+      stdio: "ignore",
+    });
+
+    signalNodeStep(child, "SIGKILL", {
+      platform: "win32",
+      runTaskkill,
+    });
+    expect(runTaskkill).toHaveBeenNthCalledWith(2, "taskkill", ["/PID", "12345", "/T", "/F"], {
+      stdio: "ignore",
+    });
+    expect(child.kill).not.toHaveBeenCalled();
+  });
+
   it.runIf(process.platform !== "win32")(
     "force-kills aborted sibling step process groups",
     async () => {