Idk if hn is psychic but I just thought how great it could be if I could use my workstation in the next room as a host for writing code on my phone. Because I can take my phone where I'm comfortable and hold it where I please and lay on the sofa, relaxed as opposed to sitting on a chair where blood flow to my feet is semi cut off. (How I would love one of those walk-apparatuses Linus Torvalds has).

So sorry no answer, but also interested.

I remember there were a few online code editors, but trust is an issue and they cost extra.

The way you intend to use it though... I have done it in my PHP days, long ago. It's not good practice. Version control systems are a good invention, even if you sometimes just need a quick fix. Edit locally, push to repo, auto build or manually.