fix(browser): preserve external defaults during CDP attachment

Use Playwright’s public noDefaults connection option and keep temporary focus under the selected page’s existing environment owner. Preserve unrelated page media and avoid creating a bootstrap target or retrying a failed handshake.

Extend real CLI/MCP environment verification with an independently observed unselected page and stable page inventory. Cover late focus acquisition and cleanup retry; retain verified upstream license notices for the required SDK upgrade.

Assisted-by: Kogasa (gensokyo-skills:kogasa-surprise-testing)

docs/browser-scenario-contract.md

@@ -173,6 +173,12 @@ distinction: it closes and deletes provider-owned profiles, but only disconnects
 from an external CDP browser. Real-browser verification checks both outcomes and
 confirms that an attached external browser remains alive.
 
+CDP connections leave Playwright's default-context overrides disabled. The
+selected page receives the declared scenario environment and temporary focus
+emulation, so actions can complete while that page is in the background.
+Its environment owner clears these overrides before disconnecting; other pages
+keep their media settings. Connecting does not create a bootstrap page.
+
 That cleanup requires REA to remain running. Abrupt termination, including
 Windows process-tree termination or POSIX `SIGKILL`, can leave the launch
 profile and Playwright artifacts behind. A profile can retain cookies, history,

licenses/npm-dependencies.txt

@@ -3710,11 +3710,11 @@ [email protected] | runtime | MIT
   Package: https://www.npmjs.com/package/pkce-challenge/v/5.0.1
   Archive: https://registry.npmjs.org/pkce-challenge/-/pkce-challenge-5.0.1.tgz
   Integrity: sha512-wQ0b/W4Fr01qtpHlqSqspcj3EhBvimsdh0KlHhH8HRZnMsEa0ea2fTULOXOS9ccQr3om+GcGRk4e+isrZWV8qQ==
-playwright-core@1.58.2 | runtime | Apache-2.0
+playwright-core@1.64.1 | runtime | Apache-2.0
   Lockfile path: node_modules/playwright-core
-  Package: https://www.npmjs.com/package/playwright-core/v/1.58.2
-  Archive: https://registry.npmjs.org/playwright-core/-/playwright-core-1.58.2.tgz
-  Integrity: sha512-yZkEtftgwS8CsfYo7nm0KE8jsvm6i/PTgVtB8DL726wNf6H2IMsDuxCpJj59KDaxCtSnrWan2AeDqM7JBaultg==
+  Package: https://www.npmjs.com/package/playwright-core/v/1.64.1
+  Archive: https://registry.npmjs.org/playwright-core/-/playwright-core-1.64.1.tgz
+  Integrity: sha512-BC4s8y6SEVA6Q1rSxZTto8hI1KUI3xXlHGZgvGqP4IqPdI/a6FX9H29IDNz7vKo9l21b6LfYosScPL6M3xxyDQ==
 [email protected] | runtime | MIT
   Lockfile path: node_modules/plist
   Package: https://www.npmjs.com/package/plist/v/5.0.0

package-lock.json

@@ -39,7 +39,7 @@
         "openpgp": "6.3.2",
         "parse5": "8.0.1",
         "pino": "10.4.0",
-        "playwright-core": "1.58.2",
+        "playwright-core": "1.64.1",
         "plist": "5.0.0",
         "saxes": "6.0.0",
         "semver": "7.8.5",
@@ -10529,15 +10529,15 @@
       }
     },
     "node_modules/playwright-core": {
-      "version": "1.58.2",
-      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.58.2.tgz",
-      "integrity": "sha512-yZkEtftgwS8CsfYo7nm0KE8jsvm6i/PTgVtB8DL726wNf6H2IMsDuxCpJj59KDaxCtSnrWan2AeDqM7JBaultg==",
+      "version": "1.64.1",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.64.1.tgz",
+      "integrity": "sha512-BC4s8y6SEVA6Q1rSxZTto8hI1KUI3xXlHGZgvGqP4IqPdI/a6FX9H29IDNz7vKo9l21b6LfYosScPL6M3xxyDQ==",
       "license": "Apache-2.0",
       "bin": {
         "playwright-core": "cli.js"
       },
       "engines": {
-        "node": ">=18"
+        "node": ">=20"
       }
     },
     "node_modules/plist": {

package.json

@@ -368,7 +368,7 @@
     "openpgp": "6.3.2",
     "parse5": "8.0.1",
     "pino": "10.4.0",
-    "playwright-core": "1.58.2",
+    "playwright-core": "1.64.1",
     "plist": "5.0.0",
     "saxes": "6.0.0",
     "semver": "7.8.5",

scripts/lib/browser-scenario-environment-e2e.mjs

@@ -140,9 +140,54 @@ export async function verifyScenarioEnvironment(endpoint, targetId, origin) {
     return JSON.parse(value.result.value);
   };
   const provider = createBrowserScenarioProvider(process.env);
+  let unselected;
+  let unselectedTarget;
   return withVerifierCleanup(async () => {
+    // The fixture owns this extra page. A scenario selecting targetId must not
+    // initialize Playwright defaults on another caller-owned page.
+    const created = await connection.send("Target.createTarget", {
+      url: "about:blank",
+    });
+    unselectedTarget = created.targetId;
+    const pages = await (await fetch(`${endpoint}/json/list`)).json();
+    const other = pages.find(({ id }) => id === unselectedTarget);
+    assert.ok(other, "Owned unselected fixture page is missing");
+    unselected = await CdpConnection.connect(
+      other.webSocketDebuggerUrl,
+      "capture_browser_scenario",
+    );
+    const pageIds = pages
+      .filter(({ type }) => type === "page")
+      .map(({ id }) => id)
+      .sort();
+    await unselected.send("Emulation.setEmulatedMedia", {
+      features: [{ name: "prefers-color-scheme", value: "dark" }],
+    });
+    const assertUnselectedState = async () => {
+      const observed = await unselected.send("Runtime.evaluate", {
+        expression: "matchMedia('(prefers-color-scheme: dark)').matches",
+        returnByValue: true,
+      });
+      assert.equal(
+        observed.result.value,
+        true,
+        "Scenario attachment changed media on an unselected page",
+      );
+    };
+    await assertUnselectedState();
+    // Settle the selected tab's actual layout before taking the restoration
+    // baseline, then leave it in the background for the scenario's actions.
+    await connection.send("Target.activateTarget", { targetId });
+    await connection.send("Runtime.evaluate", {
+      expression:
+        "new Promise(resolve => requestAnimationFrame(() => requestAnimationFrame(resolve)))",
+      awaitPromise: true,
+    });
     const baseline = await readEnvironment();
     const callerLanguage = await readEnvironment(languageExpression);
+    await connection.send("Target.activateTarget", {
+      targetId: unselectedTarget,
+    });
     const scenario = environmentScenario({
       endpoint,
       targetId,
@@ -157,6 +202,14 @@ export async function verifyScenarioEnvironment(endpoint, targetId, origin) {
       );
       const remaining = await (await fetch(`${endpoint}/json/list`)).json();
       assert.ok(remaining.some(({ id }) => id === targetId));
+      assert.deepEqual(
+        remaining
+          .filter(({ type }) => type === "page")
+          .map(({ id }) => id)
+          .sort(),
+        pageIds,
+        "Scenario attachment changed the caller's page inventory",
+      );
     };
     const cliCapture = (await runScenarioCli(scenario)).normalized_result;
     assertCapture(cliCapture);
@@ -195,6 +248,7 @@ export async function verifyScenarioEnvironment(endpoint, targetId, origin) {
         targetId,
         origin,
         assertRestored,
+        assertUnselectedState,
       });
     }, [() => client.close(), () => transport.close()]);
     await assertRestored();
@@ -235,8 +289,25 @@ export async function verifyScenarioEnvironment(endpoint, targetId, origin) {
       action_failure_cleanup: true,
       cancellation_cleanup: true,
       external_target_preserved: true,
+      unselected_page_media_preserved: true,
     };
-  }, [() => provider.close(), () => connection.close()]);
+  }, [
+    () => provider.close(),
+    () => unselected?.close(),
+    async () => {
+      if (unselectedTarget !== undefined)
+        assert.equal(
+          (
+            await connection.send("Target.closeTarget", {
+              targetId: unselectedTarget,
+            })
+          ).success,
+          true,
+          "Owned unselected fixture page was not released",
+        );
+    },
+    () => connection.close(),
+  ]);
 }
 
 const verifyConcurrentMcpCapture = async ({
@@ -247,6 +318,7 @@ const verifyConcurrentMcpCapture = async ({
   targetId,
   origin,
   assertRestored,
+  assertUnselectedState,
 }) => {
   const firstScenario = environmentScenario({
     endpoint,
@@ -279,6 +351,7 @@ const verifyConcurrentMcpCapture = async ({
   try {
     const first = callTool(firstScenario, firstCancellation.signal);
     await waitForEnvironment(connection, expected, "A");
+    await assertUnselectedState();
 
     const second = callTool(secondScenario, secondCancellation.signal);
     await client.ping();

src/browser/PlaywrightScenarioBrowser.test.ts

@@ -387,6 +387,11 @@ it("restores its environment overrides before releasing an attached browser", as
   const cleanupOrder: string[] = [];
   const fixture = attachedBrowserFixture({
     send: async (method, parameters) => {
+      if (
+        method === "Emulation.setFocusEmulationEnabled" &&
+        (parameters as { enabled?: boolean }).enabled === false
+      )
+        cleanupOrder.push("focus");
       if (
         method === "Emulation.setTimezoneOverride" &&
         (parameters as { timezoneId?: string }).timezoneId === ""
@@ -435,6 +440,7 @@ it("restores its environment overrides before releasing an attached browser", as
   expect(fixture.environmentSession.detach).toHaveBeenCalledOnce();
   expect(fixture.browser.close).toHaveBeenCalledOnce();
   expect(cleanupOrder).toEqual([
+    "focus",
     "timezone",
     "locale",
     "device-metrics",
@@ -488,33 +494,40 @@ it("checks a late stop after attached restoration and before transport disconnec
   ]);
 });
 
-it("retains attached environment ownership until a failed reset can be retried", async () => {
-  let localeResetAttempts = 0;
-  const fixture = attachedBrowserFixture({
-    send: async (method, parameters) => {
-      if (
-        method === "Emulation.setLocaleOverride" &&
-        (parameters as { locale?: string }).locale === ""
-      ) {
-        localeResetAttempts += 1;
-        if (localeResetAttempts === 1) throw new Error("reset interrupted");
-      }
-    },
-  });
-  const opened = await fixture.open();
+it.each(["locale", "focus"] as const)(
+  "retains a failed %s reset for cleanup retry",
+  async (mutation) => {
+    let resetAttempts = 0;
+    const fixture = attachedBrowserFixture({
+      send: async (method, parameters) => {
+        if (
+          (mutation === "locale" &&
+            method === "Emulation.setLocaleOverride" &&
+            (parameters as { locale?: string }).locale === "") ||
+          (mutation === "focus" &&
+            method === "Emulation.setFocusEmulationEnabled" &&
+            (parameters as { enabled?: boolean }).enabled === false)
+        ) {
+          resetAttempts += 1;
+          if (resetAttempts === 1) throw new Error("reset interrupted");
+        }
+      },
+    });
+    const opened = await fixture.open();
 
-  await expect(opened.cleanup.close()).rejects.toMatchObject({
-    reason: "cleanup_failed",
-    cleanup: { reason: "reset interrupted" },
-  });
-  expect(fixture.browser.close).not.toHaveBeenCalled();
-  expect(fixture.environmentSession.detach).not.toHaveBeenCalled();
+    await expect(opened.cleanup.close()).rejects.toMatchObject({
+      reason: "cleanup_failed",
+      cleanup: { reason: "reset interrupted" },
+    });
+    expect(fixture.browser.close).not.toHaveBeenCalled();
+    expect(fixture.environmentSession.detach).not.toHaveBeenCalled();
 
-  await opened.cleanup.close();
-  expect(localeResetAttempts).toBe(2);
-  expect(fixture.environmentSession.detach).toHaveBeenCalledOnce();
-  expect(fixture.browser.close).toHaveBeenCalledOnce();
-});
+    await opened.cleanup.close();
+    expect(resetAttempts).toBe(2);
+    expect(fixture.environmentSession.detach).toHaveBeenCalledOnce();
+    expect(fixture.browser.close).toHaveBeenCalledOnce();
+  },
+);
 
 it("does not clear an attached environment override it failed to acquire", async () => {
   const fixture = attachedBrowserFixture({
@@ -1260,75 +1273,96 @@ it("closes a browser that connects after its deadline without waiting to report
   expect(closed).toBe(true);
 });
 
-it("restores an environment mutation that completes after its deadline", async () => {
-  let restored = false;
-  const scenario = browserScenarioSchema.parse({
-    browser: {
-      mode: "connect",
-      cdp_endpoint: "http://127.0.0.1:9222",
-      target_id: "late-environment-target",
-    },
-    start_url: { url: "https://example.test" },
-    environment: { service_workers: "allow" },
-    command_timeout_ms: 40,
-    actions: scenarioActions,
-  });
-  const discoverySession = {
-    send: vi.fn(async () => ({
-      targetInfo: { targetId: "late-environment-target" },
-    })),
-    detach: vi.fn(async () => undefined),
-  } as unknown as CDPSession;
-  const environmentSession = {
-    send: vi.fn(async () => undefined),
-    detach: vi.fn(async () => undefined),
-  } as unknown as CDPSession;
-  const page = {
-    emulateMedia: vi.fn(async (options: { colorScheme?: string | null }) => {
-      if (options.colorScheme === null) {
-        restored = true;
-        return;
-      }
-      await new Promise((resolve) => setTimeout(resolve, 80));
-    }),
-    isClosed: vi.fn(() => false),
-  } as unknown as Page;
-  const context = {
-    pages: () => [page],
-    newCDPSession: vi
-      .fn()
-      .mockResolvedValueOnce(discoverySession)
-      .mockResolvedValueOnce(environmentSession),
-  } as unknown as BrowserContext;
-  const browser = {
-    close: vi.fn(async () => undefined),
-    contexts: () => [context],
-    isConnected: vi.fn(() => true),
-    version: () => "late-environment",
-  };
-  await expect(
-    openPlaywrightScenarioBrowser(
-      scenario,
-      {},
-      {
-        launcher: {
-          connectOverCDP: async () => browser,
-          launchPersistentContext: async () => {
-            throw new Error("Unexpected launch");
+it.each(["media", "focus"] as const)(
+  "restores a late %s mutation after its deadline",
+  async (mutation) => {
+    let restored = false;
+    const scenario = browserScenarioSchema.parse({
+      browser: {
+        mode: "connect",
+        cdp_endpoint: "http://127.0.0.1:9222",
+        target_id: "late-environment-target",
+      },
+      start_url: { url: "https://example.test" },
+      environment: { service_workers: "allow" },
+      command_timeout_ms: 40,
+      actions: scenarioActions,
+    });
+    const discoverySession = {
+      send: vi.fn(async () => ({
+        targetInfo: { targetId: "late-environment-target" },
+      })),
+      detach: vi.fn(async () => undefined),
+    } as unknown as CDPSession;
+    const environmentSession = {
+      send: vi.fn(
+        async (method: string, parameters?: { enabled?: boolean }) => {
+          if (method !== "Emulation.setFocusEmulationEnabled") return;
+          if (parameters?.enabled === false) {
+            if (mutation === "focus") restored = true;
+          } else if (mutation === "focus")
+            await new Promise((resolve) => setTimeout(resolve, 80));
+        },
+      ),
+      detach: vi.fn(async () => undefined),
+    } as unknown as CDPSession;
+    const page = {
+      emulateMedia: vi.fn(async (options: { colorScheme?: string | null }) => {
+        if (options.colorScheme === null) {
+          if (mutation === "media") restored = true;
+          return;
+        }
+        if (mutation === "media")
+          await new Promise((resolve) => setTimeout(resolve, 80));
+      }),
+      isClosed: vi.fn(() => false),
+    } as unknown as Page;
+    const context = {
+      pages: () => [page],
+      newCDPSession: vi
+        .fn()
+        .mockResolvedValueOnce(discoverySession)
+        .mockResolvedValueOnce(environmentSession),
+    } as unknown as BrowserContext;
+    const browser = {
+      close: vi.fn(async () => undefined),
+      contexts: () => [context],
+      isConnected: vi.fn(() => true),
+      version: () => "late-environment",
+    };
+    await expect(
+      openPlaywrightScenarioBrowser(
+        scenario,
+        {},
+        {
+          launcher: {
+            connectOverCDP: async () => browser,
+            launchPersistentContext: async () => {
+              throw new Error("Unexpected launch");
+            },
           },
         },
-      },
-    ),
-  ).rejects.toMatchObject({
-    reason: "timeout",
-    userMessage: expect.stringContaining("Emulation.setEmulatedMedia"),
-  });
-  expect(restored).toBe(true);
-  expect(environmentSession.send).not.toHaveBeenCalledWith(
-    "Emulation.clearDeviceMetricsOverride",
-  );
-  expect(browser.close).toHaveBeenCalledOnce();
-});
+      ),
+    ).rejects.toMatchObject({
+      reason: "timeout",
+      userMessage: expect.stringContaining(
+        mutation === "media"
+          ? "Emulation.setEmulatedMedia"
+          : "Emulation.setFocusEmulationEnabled",
+      ),
+    });
+    expect(restored).toBe(true);
+    if (mutation === "media")
+      expect(environmentSession.send).not.toHaveBeenCalledWith(
+        "Emulation.clearDeviceMetricsOverride",
+      );
+    else
+      expect(environmentSession.send).toHaveBeenCalledWith(
+        "Emulation.clearDeviceMetricsOverride",
+      );
+    expect(browser.close).toHaveBeenCalledOnce();
+  },
+);
 
 it.each([
   new Error("Timeout unrelated launch diagnostic"),

src/browser/PlaywrightScenarioBrowser.ts

@@ -13,6 +13,7 @@ import type {
   Browser,
   BrowserContext,
   CDPSession,
+  ConnectOverCDPOptions,
   Page,
   chromium,
 } from "playwright-core";
@@ -435,6 +436,7 @@ const findConnectedPage = async (
 
 /** Owns the target state changed while one scenario uses an attached page. */
 class AttachedScenarioEnvironmentOwner {
+  #focusOverride = false;
   #mediaOverride = false;
   #deviceMetricsOverride = false;
   #localeOverride = false;
@@ -475,6 +477,7 @@ class AttachedScenarioEnvironmentOwner {
 
   get restored(): boolean {
     return (
+      !this.#focusOverride &&
       !this.#mediaOverride &&
       !this.#deviceMetricsOverride &&
       !this.#localeOverride &&
@@ -563,6 +566,18 @@ class AttachedScenarioEnvironmentOwner {
       "Emulation.setTimezoneOverride",
     );
     throwIfScenarioCancelled(signal);
+
+    // Keep scenario actions usable in the selected background page without
+    // Playwright's connection-wide focus override on unrelated pages.
+    await this.#command(
+      this.session
+        .send("Emulation.setFocusEmulationEnabled", { enabled: true })
+        .then(() => {
+          this.#focusOverride = true;
+        }),
+      "Emulation.setFocusEmulationEnabled",
+    );
+    throwIfScenarioCancelled(signal);
   }
 
   async close(): Promise<void> {
@@ -577,6 +592,16 @@ class AttachedScenarioEnvironmentOwner {
       await settleScenarioCommand(cause);
     }
     const failures: unknown[] = [];
+    if (this.#focusOverride) {
+      try {
+        await this.session.send("Emulation.setFocusEmulationEnabled", {
+          enabled: false,
+        });
+        this.#focusOverride = false;
+      } catch (cause: unknown) {
+        failures.push(cause);
+      }
+    }
     if (this.#timezoneOverride) {
       try {
         await this.session.send("Emulation.setTimezoneOverride", {
@@ -669,7 +694,7 @@ type ScenarioBrowserLauncher = Pick<
 > & {
   readonly connectOverCDP: (
     endpoint: string,
-    options?: { readonly timeout?: number },
+    options?: Pick<ConnectOverCDPOptions, "timeout" | "noDefaults">,
   ) => Promise<Pick<Browser, "contexts" | "close" | "isConnected" | "version">>;
 };
 
@@ -698,6 +723,10 @@ const openAttachedScenarioBrowser = async (
       () =>
         launcher.connectOverCDP(browserRequest.cdp_endpoint, {
           timeout: commandTimeoutMs,
+          // Only the selected target's environment owner may apply overrides.
+          // Playwright defaults also mutate unrelated external pages and can
+          // require context management on an otherwise usable CDP endpoint.
+          noDefaults: true,
         }),
       commandTimeoutMs,
       "handshake",

src/browser/PlaywrightScenarioRequest.test.ts

@@ -341,6 +341,10 @@ describe("request dispatch boundary", () => {
     let gate: ((route: Route) => Promise<void>) | undefined;
     vi.spyOn(page, "route").mockImplementation(async (_match, handler) => {
       gate = handler as typeof gate;
+      return {
+        dispose: async () => undefined,
+        [Symbol.asyncDispose]: async () => undefined,
+      };
     });
     const unroute = vi.spyOn(page, "unroute");
     const sent = vi.fn();

tests/fixtures/webModuleTrace.ts

@@ -101,7 +101,10 @@ export const completedModuleResolverLauncher =
     return {
       version: () => "controlled-browser",
       newContext: async () => ({
-        route: async () => {},
+        route: async () => ({
+          dispose: async () => undefined,
+          [Symbol.asyncDispose]: async () => undefined,
+        }),
         newPage: async () => ({
           on: () => {},
           goto: async () => null,