Click evolved unfortunately really badly the last two releases because the internal logic just grew too complex and it's totally not sound. This needs to be cleaned up but I'm not yet sure how.

Click needs to somehow become a pipeline that is clearly separated to be able to work better. Starting with parsing, handling of value callbacks and then invoking the callbacks. Maybe we need to split this pipeline into more steps where we can have args that are not yet processed by callbacks somehow?

Some effects of the current broken handling:

• CLI: "flask" command help doesn't list custom commands flask#1124 (auto help does not invoke callbacks)
• chain is broken. There is a failing testcase in the repo