rem-learn

Extract permanent lessons from the current session so they're never repeated. Mines git diff / reflog / conversation for error→fix chains, silent failures (code ran but produced wrong data), near-misses (almost deployed X), wasted effort (spent 30m on wrong approach), positive patterns worth replicating, and architecture insights uncovered during debugging. Writes grep-able entries to learnings.md / auto-memory / CLAUDE.md with code, exact error messages, dates, keywords — NOT "be more careful with types". Escalates 3+ similar entries to project CLAUDE.md conventions, universal lessons to global ~/.claude/CLAUDE.md. Prunes stale entries, keeps MEMORY.md under 200 lines. Distinct from rem-handoff (which saves session-resumption state, not lessons). Use for "learn from this", "remember this", "update learnings", "never do this again", "capture lessons", "save what we learned", or after any debugging / error session.