What is the difference between an access token and a refresh token?

An access token is a short-lived pass attached to every resource request; a refresh token is long-lived and is used to obtain a new pass when the access token no longer goes through.

When a token expires, do I have to send the user back to log in?

Not necessarily. If the refresh token is still alive, you can fetch a new access token and carry on the request in flight, so the user feels no interruption.

Auto-refresh the login tokenWorkplace case

A real-world situation reported by 박**

Your task

When the token of a user signed in with Chzzk OAuth expires, refresh it automatically so the request can continue. When a resource call returns 401 because the access token has expired, get a new token with the refresh token and call again. Complete request in api-client.ts. Note: the server calls (callResource, refreshTokens) and the token store (tokenStore) are already there. You only fill in request.

Ground rules

•Access-token expiry and refresh are simulated by the provided server module (auth-server.ts).
•Do not change the server calls or the token store (auth-server.ts, token-store.ts).

Not required

•The actual OAuth login screen and callback handling.
•Implementing a token store (cookie / local storage).

▶About this challenge

A problem where you complete, with Next.js (App Router) and TypeScript, the flow that keeps a signed-in user's session unbroken by fetching a fresh token when the old one stops working. When a resource call no longer goes through, you get a new token and call again — filled into request in api-client.

With short-lived tokens, a good experience is to quietly fetch a new token and carry the session on, rather than bouncing the user back to a login screen when the token stops working. This "unbroken session" shows up on almost every screen that uses token-based auth, and this problem implements that flow directly.

What is the difference between an access token and a refresh token?: An access token is a short-lived pass attached to every resource request; a refresh token is long-lived and is used to obtain a new pass when the access token no longer goes through.
When a token expires, do I have to send the user back to log in?: Not necessarily. If the refresh token is still alive, you can fetch a new access token and carry on the request in flight, so the user feels no interruption.

Auto-refresh the login tokenWorkplace case

A real-world situation reported by 박**

Your task

Ground rules

•Access-token expiry and refresh are simulated by the provided server module (auth-server.ts).
•Do not change the server calls or the token store (auth-server.ts, token-store.ts).

Not required

•The actual OAuth login screen and callback handling.
•Implementing a token store (cookie / local storage).

▶About this challenge

What is the difference between an access token and a refresh token?: An access token is a short-lived pass attached to every resource request; a refresh token is long-lived and is used to obtain a new pass when the access token no longer goes through.
When a token expires, do I have to send the user back to log in?: Not necessarily. If the refresh token is still alive, you can fetch a new access token and carry on the request in flight, so the user feels no interruption.