https://redbean.dev/ could be just perfect fit for you

I tried it in the early days but couldn't get it to work on my mac. Also, I'm very familiar with Lua source code and LuaRocks so I chose comfort. Redbean is amazing though and I really want to take it for a spin some day.

Before Sublime Text I did use - PSPad http://www.pspad.com/en/

I hacked something during the night that supports changes. It creates new commit inside repository for each change.

https://github.com/mochja/giftp

I use Pencil, too.

It has some limited features and the UX could be better, but it is open source and works across Linux, OSX and Windows, so other people on the team can edit diagrams I have created.

I changed from Windows/Linux to OS X. It's much better now.