PH5h5W6d2L

Autonomous high-reasoning operating mode for Claude Code. Gives any model (Opus 4.8, Sonnet, etc.) the working behaviors that made Claude Fable 5 valuable — long-horizon planning, proactive autonomy, self-verification, sub-agent delegation, evidence-grounded progress, effort calibration, and persistent memory across a run. Load when the user says "use fable mode" or kicks off ambitious, long-running, multi-step work meant to go start-to-finish with minimal supervision. Changes how the model works, not which model is running.