Ask questions about authentication: how to integrate third-party authentication to facilitate docking with existing users

This answer is very easy to use and neat; want to organize and use the existing business system, but it is troublesome to let users re-register. In order to better interact with users, it is necessary to increase users' third-party authentication, such as QQ and Wechat.

The issue names no files, tests, or entry points. Begin by clarifying the required QQ and WeChat authentication flows, how existing users should be matched, and which plugin extension point should own the integration. Done should include an agreed scope and an implementation path that supports third-party sign-in without forcing existing users to re-register.

Written by the indexing model from the issue text.