RTK Query + Redux + Next.js 15 Authentication Flow Issue (Session Hydration Delay)

[jsdev-robin]

I'm currently working with a Next.js 15 app using the App Router, and I'm handling authentication using RTK Query along with Redux Toolkit. My flow is:

1. After signing in, an accessToken is saved automatically in a browser cookie.

2. On subsequent page loads, I use a GET /me API request to retrieve the authenticated user.

3. Once the response arrives, I dispatch userSignin to update the authSlice with the session data (user, isAuth, and accessToken).

Everything works as expected, except for one critical issue:

The page renders before the session data is available in Redux.
As a result, route protection logic (implemented via a HOC or wrapper component) runs before authSlice.user or authSlice.isAuth is set — causing unauthenticated redirects even when a valid session exists.

This means:

Even though the user has a valid session cookie,

And the server returns the correct user via /me,

The page still redirects to /signin because Redux hasn't been updated in time.

I'm wondering if others have faced this session hydration timing issue with:

Next.js 15 (App Router)

Redux Toolkit + RTK Query

Cookie-based authentication

Client-side route protection (using authSlice state)

Looking for best practices to:

Delay route protection logic until the session is hydrated,

Or move session validation to middleware for early request-time decisions.

Any suggestions or links to relevant discussions are appreciated!