Ask HN: Version and store collaborative task lists, data formats and branching

I'm looking for advice and ideas on the best way to store and manage a collaborative notes/task list.

The most obvious/easiest way would be to use markdown and git in the background and then store metadata in the database, but i feel like this inviting all sorts of trouble, including the need for building a proper merge interface which I'd like to avoid.

Does any one have a suggestion on how to address that? It also seems like most people use markdown with hidden annotations to embed images at certain locations.

Is there a better way to do this?