Ask HN: What are your productivity hacks as a sole programmer on a project?

keep things as simple as possible both in design and dependencies

write tests so you can iterate fast later on when you need to change code and ensure that it does not break things.

write a little documentation to help you remember something about the top level design, what each directory is for, and what the major files are.

automate as much of the build, test, and deploy process as possible so its easy to fix things and roll them out later on.