concertonotes OAUTH
Use when a val needs to require login with a Val Town account — gating routes behind authentication, identifying the current user, building user-specific dashboards. Covers std/oauth's `oauthMiddleware` and `getOAuthUserData`, the auto-managed `/auth/*` routes, and session behavior. For third-party OAuth providers (Google, GitHub, etc.) see the `third-party-integrations` skill instead.