fix(browser): wait for CDP readiness after start (#21149)

AaronWander · steipete · commit d06cc77f38a1 · 2026-03-02T13:53:21.000Z
diff --git a/src/browser/server-context.ensure-browser-available.waits-for-cdp-ready.test.ts b/src/browser/server-context.ensure-browser-available.waits-for-cdp-ready.test.ts
@@ -0,0 +1,77 @@
+import type { ChildProcessWithoutNullStreams } from "node:child_process";
+import { EventEmitter } from "node:events";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import * as chromeModule from "./chrome.js";
+import "./server-context.chrome-test-harness.js";
+import type { BrowserServerState } from "./server-context.js";
+import { createBrowserRouteContext } from "./server-context.js";
+
+function makeBrowserState(): BrowserServerState {
+  return {
+    // oxlint-disable-next-line typescript/no-explicit-any
+    server: null as any,
+    port: 0,
+    resolved: {
+      enabled: true,
+      controlPort: 18791,
+      cdpProtocol: "http",
+      cdpHost: "127.0.0.1",
+      cdpIsLoopback: true,
+      evaluateEnabled: false,
+      remoteCdpTimeoutMs: 1500,
+      remoteCdpHandshakeTimeoutMs: 3000,
+      extraArgs: [],
+      color: "#FF4500",
+      headless: true,
+      noSandbox: false,
+      attachOnly: false,
+      ssrfPolicy: { allowPrivateNetwork: true },
+      defaultProfile: "openclaw",
+      profiles: {
+        openclaw: { cdpPort: 18800, color: "#FF4500" },
+      },
+    },
+    profiles: new Map(),
+  };
+}
+
+afterEach(() => {
+  vi.useRealTimers();
+  vi.restoreAllMocks();
+});
+
+describe("browser server-context ensureBrowserAvailable", () => {
+  it("waits for CDP readiness after launching to avoid follow-up PortInUseError races (#21149)", async () => {
+    vi.useFakeTimers();
+
+    const launchOpenClawChrome = vi.mocked(chromeModule.launchOpenClawChrome);
+    const stopOpenClawChrome = vi.mocked(chromeModule.stopOpenClawChrome);
+    const isChromeReachable = vi.mocked(chromeModule.isChromeReachable);
+    const isChromeCdpReady = vi.mocked(chromeModule.isChromeCdpReady);
+
+    isChromeReachable.mockResolvedValue(false);
+    isChromeCdpReady.mockResolvedValueOnce(false).mockResolvedValue(true);
+
+    const proc = new EventEmitter() as unknown as ChildProcessWithoutNullStreams;
+    launchOpenClawChrome.mockResolvedValue({
+      pid: 123,
+      exe: { kind: "chromium", path: "/usr/bin/chromium" },
+      userDataDir: "/tmp/openclaw-test",
+      cdpPort: 18800,
+      startedAt: Date.now(),
+      proc,
+    });
+
+    const state = makeBrowserState();
+    const ctx = createBrowserRouteContext({ getState: () => state });
+    const profile = ctx.forProfile("openclaw");
+
+    const promise = profile.ensureBrowserAvailable();
+    await vi.advanceTimersByTimeAsync(100);
+    await expect(promise).resolves.toBeUndefined();
+
+    expect(launchOpenClawChrome).toHaveBeenCalledTimes(1);
+    expect(isChromeCdpReady).toHaveBeenCalled();
+    expect(stopOpenClawChrome).not.toHaveBeenCalled();
+  });
+});
diff --git a/src/browser/server-context.ts b/src/browser/server-context.ts
@@ -282,6 +282,21 @@ function createProfileContext(
     const isExtension = profile.driver === "extension";
     const profileState = getProfileState();
     const httpReachable = await isHttpReachable();
+    const waitForCdpReadyAfterLaunch = async () => {
+      // launchOpenClawChrome() can return before Chrome is fully ready to serve /json/version + CDP WS.
+      // If a follow-up call (snapshot/screenshot/etc.) races ahead, we can hit PortInUseError trying to
+      // launch again on the same port. Poll briefly so browser(action="start"/"open") is stable.
+      const maxAttempts = 50;
+      for (let attempt = 0; attempt < maxAttempts; attempt++) {
+        if (await isReachable(1200)) {
+          return;
+        }
+        await new Promise((r) => setTimeout(r, 100));
+      }
+      throw new Error(
+        `Chrome CDP websocket for profile "${profile.name}" is not reachable after start.`,
+      );
+    };
 
     if (isExtension && remoteCdp) {
       throw new Error(
@@ -319,6 +334,13 @@ function createProfileContext(
       }
       const launched = await launchOpenClawChrome(current.resolved, profile);
       attachRunning(launched);
+      try {
+        await waitForCdpReadyAfterLaunch();
+      } catch (err) {
+        await stopOpenClawChrome(launched).catch(() => {});
+        setProfileRunning(null);
+        throw err;
+      }
       return;
     }
 
