OAuth login flow
Prompt
Create a UML sequence diagram for OAuth 2.0 PKCE login: user in browser, frontend app, authorization server, and resource API. Show authorization request, code exchange, token validation, refresh token rotation, and expired refresh token error path.
Why this prompt works
It names the exact actors and important alternate path, which makes the diagram more useful than a happy-path-only version.
Follow-up prompt
Add an MFA challenge branch after primary authentication and highlight token storage rules in the frontend.