Fix OAuth sign-in app state handling

src/hooks/__tests__/useQuantumAuth.test.tsx

@@ -1,5 +1,5 @@
 import { fireEvent, render, waitFor } from "@testing-library/react-native";
-import { Pressable, Text, View } from "react-native";
+import { AppState, Pressable, Text, View } from "react-native";
 
 import {
   clearStoredAuthSession,
@@ -95,6 +95,52 @@ describe("useQuantumAuth", () => {
     );
   });
 
+  it("keeps the OAuth operation alive while the auth browser backgrounds the app", async () => {
+    const signedInSession: StoredAuthSession = {
+      accessToken: "access-token",
+      expiresAt: Math.floor(Date.now() / 1000) + 3600,
+      idToken: "id-token",
+      issuedAt: Math.floor(Date.now() / 1000),
+      refreshToken: "refresh-token",
+      user: {
+        email: "user@chefuinc.com",
+        uid: "user-1",
+      },
+    };
+    let appStateListener: ((state: string) => void) | undefined;
+    jest
+      .spyOn(AppState, "addEventListener")
+      .mockImplementation((_event, listener) => {
+        appStateListener = listener as (state: string) => void;
+        return { remove: jest.fn() } as never;
+      });
+    let finishSignIn: ((session: StoredAuthSession) => void) | undefined;
+    jest.mocked(startQuantumSignIn).mockImplementation(
+      () =>
+        new Promise(resolve => {
+          finishSignIn = resolve;
+        }),
+    );
+
+    const view = await render(<AuthHarness />);
+
+    await waitFor(() =>
+      expect(view.getByTestId("status").props.children).toBe("guest"),
+    );
+    fireEvent.press(view.getByText("Sign in"));
+    appStateListener?.("background");
+    finishSignIn?.(signedInSession);
+
+    await waitFor(() =>
+      expect(view.getByTestId("status").props.children).toBe("authenticated"),
+    );
+    expect(saveStoredAuthSession).toHaveBeenCalledWith(signedInSession);
+    expect(view.getByTestId("notice").props.children).toBe(
+      "Signed in to CheFu Account.",
+    );
+    view.unmount();
+  });
+
   it("clears expired sessions and prompts the user to sign in again", async () => {
     const expiredSession: StoredAuthSession = {
       accessToken: "expired-access",

src/hooks/useQuantumAuth.ts

@@ -30,6 +30,7 @@ export function useQuantumAuth() {
   const [authStatus, setAuthStatus] = useState<AuthStatus>("checking");
   const [authNotice, setAuthNotice] = useState("");
   const operationRef = useRef(0);
+  const authPromptActiveRef = useRef(false);
 
   const restoreStoredSession = useCallback(async () => {
     const operationId = nextAuthOperation(operationRef);
@@ -73,6 +74,8 @@ export function useQuantumAuth() {
 
   useEffect(() => {
     const subscription = AppState.addEventListener("change", (nextState) => {
+      if (authPromptActiveRef.current) return;
+
       if (nextState === "active") {
         void restoreStoredSession();
         return;
@@ -124,7 +127,9 @@ export function useQuantumAuth() {
     setAuthStatus("checking");
 
     try {
+      authPromptActiveRef.current = true;
       const nextSession = await startQuantumSignIn();
+      authPromptActiveRef.current = false;
       if (!isCurrentAuthOperation(operationRef, operationId)) return;
 
       if (!nextSession) {
@@ -137,6 +142,7 @@ export function useQuantumAuth() {
       setAuthStatus("authenticated");
       setAuthNotice("Signed in to CheFu Account.");
     } catch (error) {
+      authPromptActiveRef.current = false;
       if (!isCurrentAuthOperation(operationRef, operationId)) return;
       setAuthStatus(session ? "authenticated" : "guest");
       setAuthNotice(authErrorMessage(error));