Looking to understand this repos branching strategy

I'm integrating sd-scripts into my own work so want to better understand how to use this repo, given it's unusual branching. I've seen @kohya-ss apologising for the "chaotic" branching in the issues for bmaltais kohya_ss UI, so I don't mean to make any judgements here, I just need to understand the facts.

As far as I can tell
* bmaltais has pinned sd-scripts to a version from 7 months ago
* Other conversations in these issues suggest the `sd3` branch is the most up-to-date

So my questions are:
* What is the purpose of the `main` branch?
* What is the future for the `sd3` branch and how truthful is the idea that `sd3` is the most up-to-date?
* Is there a plan to bring bmaltais' UI into line with sd-scripts `main`, or indeed `sd3` branches?
* Is the eventual intent to de-chaos the repo in the direction of `main` becoming stable and widely adopted (by bmaltais et al)?

Would love to understand how I can contribute here, as well as understand how I can best plan for any serious refactoring in the future.

Compare the main and sd3 branches with the version pinned by bmaltais, then review the issue discussions referenced in the message. Done means documenting the purpose, maintenance status, and intended future of each branch, including how the UI relates to them.

Written by the indexing model from the issue text.