Eagleson's Law

If

"Any code of your own that you haven't looked at for six months might as well have been written by someone else." Your mental model of the code evaporates far faster than the code does; context is not stored in the source.

Then

Write code and commit messages for the stranger you will become in six months. If a decision is not obvious from the code, record the why in a comment or an ADR — not just in your head.

Unless

ADRs / Self-Explaining Code / Code Comments on the "Why"