Persist project decisions, conventions, and session handoffs as reviewable markdown in `.agent-memory/`. Use when asked to "manage project memory", "initialize .agent-memory", "migrate memory", "build memory from docs", "save session learnings", "sync memory", "run memory maintenance", "check memory status", or "onboard a new developer"; when `.agent-memory/` or `AGENTS.md` memory pointers are in play; when sharing project context with another developer or reviewing project memory in a pull request; or when context "forgets between sessions". Sync reconciles files already in the checkout. Not for memory leaks, RAM usage, or human memory.