WeChat Open Platform — Mobile App Login (OAuth 2.0)
OAuth 2.0 authorization flow exposed by the WeChat Open Platform for native iOS, Android, and HarmonyOS apps. Apps redirect into WeChat to obtain an authorization code, then exchange it via `https://api.weixin.qq.com/sns/oauth2/access_token` for an access token (snsapi_userinfo scope), refresh tokens via `/sns/oauth2/refresh_token`, and fetch profile via `/sns/userinfo`. Access tokens expire in 7200 seconds; refresh tokens last 180 days. Underpins "Login with WeChat" across third-party mobile apps.