I don’t know about bigger projects but for my smallish solo project I have a single STATUS.md. Agents are instructed to read it first and update it at every session/commit. It’s the main handoff document and I had no problem switching between Claude Code and Codex agents.

There is a sprint based roadmap doc. We do sprint planning and each sprint has multiple sessions with session numbers. There is a backlog document to keep track of all the bugs and feature ideas. There are many ADR documents (Architectural Decision Records) which I admit can become stale in time, but Claude is quick to notice because it actually reads these. They are the main contract between us. For a new feature an ADR is written before writing any code or an old one is amended.

I assumed this was a common workflow because I just prompted Claude to setup the project using its own best practices for a lightweight document-driven development.

I believe asking the model itself is better than using a random repo. These things have access to and trained on an enormous number of projects. They know what they need.