Agent Memory — promotion is earned, not asserted

Portability: stdlib only. No database, no embeddings, no network, no LLM calls.

The problem

A project's CLAUDE.md is a memory system with one tier and no eviction: every durable fact and every passing preference land in the same always-loaded file, until the important lines are diluted by the incidental ones. Facts learned mid-session vanish at teardown unless someone writes them down.

The fix is not more storage — it is a promotion ladder. A claim earns its way toward always-loaded context by recurring; a human confirms the last step.

The four tiers

Tiers are distinguished by injection policy, not storage format.