WeChat Open Platform — Third-Party Platform API
API surface that lets authorized ISVs operate Official Accounts and Mini Programs on behalf of merchant clients ("代商家调用接口"). Covers merchant authorization onboarding, developing Mini Programs on behalf of merchants (registration, certification, code template upload, version management), initiating web authorization, handling messages and events, using the JS-SDK on behalf of accounts, cloud development integration, domain configuration, privacy settings, and merchant-violation notifications.