fix(browser): ignore handled route navigation races

Co-authored-by: Richard Steadman <198648604+Steady-ai@users.noreply.github.com>

extensions/browser/src/browser/pw-session.create-page.navigation-guard.test.ts

@@ -345,6 +345,34 @@ describe("pw-session createPageViaPlaywright navigation guard", () => {
     expect(pageClose).not.toHaveBeenCalled();
   });
 
+  it("ignores already-handled route races during guarded navigation", async () => {
+    const { pageGoto, pageClose, getRouteHandler, mainFrame } = installBrowserMocks();
+    const route = createMockRoute({
+      continue: vi.fn(async () => {
+        throw new Error("Route is already handled");
+      }),
+    });
+    pageGoto.mockImplementationOnce(async () => {
+      await dispatchMockNavigation({
+        getRouteHandler,
+        mainFrame,
+        url: "https://example.com",
+        route,
+      });
+      return null;
+    });
+
+    const created = await createPageViaPlaywright({
+      cdpUrl: "http://127.0.0.1:18792",
+      url: "https://example.com",
+    });
+
+    expect(created.targetId).toBe("TARGET_1");
+    expect(route.continue).toHaveBeenCalledTimes(1);
+    expect(pageGoto).toHaveBeenCalledTimes(1);
+    expect(pageClose).not.toHaveBeenCalled();
+  });
+
   it("propagates unsupported redirect protocols as navigation errors", async () => {
     const { pageGoto, pageClose, getRouteHandler, mainFrame } = installBrowserMocks();
     mockBlockedRedirectNavigation({

extensions/browser/src/browser/pw-session.ts

@@ -818,6 +818,18 @@ export async function assertPageNavigationCompletedSafely(
   }
 }
 
+async function continueRouteSafely(route: Route): Promise<void> {
+  try {
+    await route.continue();
+  } catch (err) {
+    const message = err instanceof Error ? err.message : "";
+    if (message.includes("Route is already handled")) {
+      return;
+    }
+    throw err;
+  }
+}
+
 export async function gotoPageWithNavigationGuard(
   opts: {
     cdpUrl: string;
@@ -841,7 +853,7 @@ export async function gotoPageWithNavigationGuard(
     const isSubframeDocument =
       !isTopLevel && isSubframeDocumentNavigationRequest(opts.page, request);
     if (!isTopLevel && !isSubframeDocument) {
-      await route.continue();
+      await continueRouteSafely(route);
       return;
     }
     try {
@@ -859,7 +871,7 @@ export async function gotoPageWithNavigationGuard(
       }
       throw err;
     }
-    await route.continue();
+    await continueRouteSafely(route);
   };
 
   await opts.page.route("**", handler);