"Didn't we decide this yesterday?" I was migrating my email out of Google. I'd spent two Claude Code sessions working on it: issues in Linear, decisions made, scripts executed. I open a third session and ask "what's left pending from the degoogle?" Silence. Total amnesia. It's like working with a brilliant teammate who shows up to the office every morning with absolutely no memory of what you did the day before. Not the decisions, not the mistakes, not the discoveries. Every session is a blank slate. And it turns out there's a file that solves exactly this problem. It's been there for months. And almost nobody knows about it. CLAUDE.md vs MEMORY.md: the manual and the notebook If you use Claude Code, you probably already know about CLAUDE.md . It's the file where you tell the AI how to work: what language to use, what tools you have, your coding conventions. CLAUDE.md is your instruction manual . You write it. You maintain it. MEMORY.md is something else. It's a field notebook that the AI writes itself.…