Phase 1: Enable prompt caching (cacheRetention: long on Claude models) Phase 2: Heartbeat cache warming (25m main, 55m default) Phase 3: Context pruning (cache-ttl mode, 1h TTL) Phase 4: Cheaper models for subagents (GLM-4.7 free tier for bulk work) All config-only, no OpenClaw code changes, fully reversible.