fix(cli): orphaned Chrome helpers no longer keep a finished snapshot from exiting (#6545)

* fix(cli): a browser's orphaned helpers no longer keep a finished snapshot from exiting

The CDP pipe sockets stayed open after Chrome exited whenever a helper process outlived it, so the CLI never reached natural exit. Destroy them when the browser process exits.

* refactor(cli): name the pipe close so launch.ts carries no new comment

* fix(cli): a browser stand-in without stdio no longer throws from the exit listener

* fix(cli): close every pipe of an exited browser, not only the CDP pair

packages/cli/src/browser/launch.pipeEof.test.ts

@@ -0,0 +1,24 @@
+import { spawn } from "node:child_process";
+import type { LaunchOptions, PuppeteerNode } from "puppeteer-core";
+import { expect, it } from "vitest";
+import { launchManagedBrowser } from "./launch.js";
+
+// A helper that outlives the browser inherits its pipes, as Chrome's crashpad handler does.
+const SPAWN_ORPHAN = `
+  require("node:child_process")
+    .spawn(process.execPath, ["-e", "setTimeout(() => {}, 4000)"], { detached: true, stdio: ["ignore", "inherit", "inherit", 3, 4] })
+    .unref();
+`;
+
+it("closes the browser's pipes when it exits, so an orphaned helper cannot hold the CLI open", async () => {
+  const child = spawn(process.execPath, ["-e", SPAWN_ORPHAN], {
+    stdio: ["pipe", "pipe", "pipe", "pipe", "pipe"],
+  });
+  const puppeteer = {
+    launch: async (_options: LaunchOptions) => ({ process: () => child }),
+  } as unknown as PuppeteerNode;
+  await launchManagedBrowser(puppeteer, { headless: true }, { diagnose: false });
+  await expect
+    .poll(() => child.stdio.every((pipe) => pipe?.destroyed), { timeout: 3000 })
+    .toBe(true);
+});

packages/cli/src/browser/launch.ts

@@ -1,3 +1,4 @@
+import type { ChildProcess } from "node:child_process";
 import { explainChromeLaunchFailure } from "@hyperframes/engine/chrome-startup";
 import type { Browser, LaunchOptions, PuppeteerNode } from "puppeteer-core";
 import { withHyperframesBrowserMarker } from "@hyperframes/core/browser-marker";
@@ -151,6 +152,10 @@ function withRemediation(error: unknown): unknown {
   return remediation ? new Error(remediation, { cause: error }) : error;
 }
 
+function destroyBrowserPipes(child: ChildProcess): void {
+  for (const pipe of child.stdio ?? []) pipe?.destroy();
+}
+
 async function launchOwnedBrowser(
   puppeteer: PuppeteerNode,
   options: LaunchOptions,
@@ -188,7 +193,10 @@ async function launchOwnedBrowser(
     browsers.add(browser);
     const watchdog = watchChromeTree(child, launchedAt);
     if (watchdog) watchdogs.set(browser, watchdog);
-    child.once("exit", () => browsers.delete(browser));
+    child.once("exit", () => {
+      browsers.delete(browser);
+      destroyBrowserPipes(child);
+    });
     return browser;
   } finally {
     clearTimeout(timer);