The plan.md approach solves something I've been struggling with on a browser automation project. When you're building something stateful (browser sessions, fingerprinting logic etc.) the "why" behind decisions gets lost fast. Not just for other devs, but for the AI itself in future sessions.

One thing I've added on top of the plan/project structure: a short `decisions.md` that logs only the non-obvious choices, like "tried X, it caused Y issue, went with Z instead". Basically the things that would make future-me or a future agent waste time rediscovering.

Do you find the plan.md files stay useful past the initial build, or do they mostly just serve as a commit artifact?