diff --git a/apps/desktop/src/preview/CdpRelay.test.ts b/apps/desktop/src/preview/CdpRelay.test.ts
index 4ec88a7cc516..a87d8af85ea0 100644
--- a/apps/desktop/src/preview/CdpRelay.test.ts
+++ b/apps/desktop/src/preview/CdpRelay.test.ts
@@ -75,6 +75,28 @@ describe("CDP relay", () => {
     });
   });
 
+  it("resumes paused child frames, so cross-site iframes run", async () => {
+    const send = vi.fn(async () => ({}));
+    const relay = createCdpRelayConnection(makeTarget(send), () => {});
+    // The page's own session is already running; only its children wait.
+    relay.receive(
+      JSON.stringify({
+        id: 1,
+        method: "Runtime.runIfWaitingForDebugger",
+        sessionId: "t3-preview-page",
+      }),
+    );
+    relay.receive(
+      JSON.stringify({
+        id: 2,
+        method: "Runtime.runIfWaitingForDebugger",
+        sessionId: "iframe-session",
+      }),
+    );
+    await settle();
+    expect(send.mock.calls).toEqual([["Runtime.runIfWaitingForDebugger", {}, "iframe-session"]]);
+  });
+
   it("routes tab events to the page session once the page is announced", async () => {
     const written: Array<Record<string, unknown>> = [];
     const relay = createCdpRelayConnection(makeTarget(vi.fn()), (raw) =>
diff --git a/apps/desktop/src/preview/CdpRelay.ts b/apps/desktop/src/preview/CdpRelay.ts
index 19000aa50c63..62c2410c19b8 100644
--- a/apps/desktop/src/preview/CdpRelay.ts
+++ b/apps/desktop/src/preview/CdpRelay.ts
@@ -158,9 +158,14 @@ export function createCdpRelayConnection(
   };
 
   const pageCommand = (command: CdpCommand): Promise<unknown> => {
-    // The page is already running; nothing waits for a debugger.
-    if (command.method === "Runtime.runIfWaitingForDebugger") return Promise.resolve({});
     const child = sessions.get(command.sessionId!) === "page" ? undefined : command.sessionId;
+    // The page itself is already running, but its child frames are not:
+    // Playwright auto-attaches with waitForDebuggerOnStart, so Chromium pauses
+    // every new cross-site iframe and worker until this reaches it. Swallowing
+    // it left sign-in checks and captchas, which run in such frames, frozen.
+    if (command.method === "Runtime.runIfWaitingForDebugger" && child === undefined) {
+      return Promise.resolve({});
+    }
     return target.send(command.method, command.params ?? {}, child);
   };