- Test roundToDifficulty: rounds 1-2 easy, 3-4 medium, 5+ hard - Test pickChallenge difficulty filtering works with round numbers - Audit prompt difficulty tags across all 16 challenge types - 8 types lack hard prompts, 3 lack medium prompts - 82.7% of prompts are untagged (no difficulty attribute) - Report written to loop/difficulty-distribution.md Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>