all plain text files in markdown format that I edit with vim.
this includes knowledge/notes and tasks/to-do lists.

They live in a git repo, so I can go back in time and see old states.
I also do hard backups every 3 months incase of serious data loss. The backup file size is only 20meg for the whole git repo and i've been doing this for 10 years now.

This git repo is cloud synced through dropbox to all my devices (a linux laptop, desktop, mobile phone).
On my mobile I edit them with the quickedit app but i could use the dropbox app as well.

I plan to switch this to a self-hosted nextcloud instance soon.

great, now the murder robots can do a victory dance in style after it slays me.

finally, someone is testing solutions for this problem.