Persistent file-based notebook (.carnet/<category>/<slug>.md, auto-expiring after 30 days of disuse) for AI agents and humans.
Use whenever saving, recalling, or organizing notes across sessions — IMPLICIT cues include the user recapping a tricky fix worth not redoing, asking 'what did we decide about X', handing off mid-task state, or setting something aside for now.
Use PROACTIVELY when you discover something a future agent would otherwise re-derive from scratch — a non-obvious library gotcha, a hard-won fix, a rejected design alternative likely to be re-proposed, an in-progress state worth resuming.
SKIP for: time-bound TODOs that need to nag (TodoWrite/Issues surface back, carnet does not), credentials/secrets (don't put them on disk), context already in a commit/PR/ADR (no double-bookkeeping).
When in doubt, prefer a brief note over losing context: unused notes expire automatically.
2026-06-21