Comprehensive guide covering the two-tier CLI architecture (top-level system commands vs sol call tool-callable functions), how to add commands at each tier, the auto-discovery pattern for apps/*/call.py, conventions (env defaults, action logging, --consent flag), full command inventory, skill system integration, and file maintenance checklists. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>