Alle gelösten Themen automatisch mit einem „gelöst"-Tag versehen?

[jomaxro (Joshua Rosenfeld)]

You shouldn’t need a tag for this. Simply use URL filters:

Can I view a list of solved and unsolved topics in a category

Yes, this can be done by adding query params: https://meta.discourse.org/c/support?solved=yes or https://meta.discourse.org/c/support?solved=no