Connecting to the bigger picture

This registry is the same one Chapter 3's PromptBuilder reads schemas from (registry.schemas()), and the same one Chapter 2's loop calls into. Chapter 7 inserts a permission check at the marked spot, turning call into a safe gate. Chapter 8 runs several calls in parallel. Chapter 10's MCP tools register themselves into this exact registry. In the capstone, this file barely changes; it is the agent's hands, and most other chapters either add tools to it or wrap it.