Connecting to the bigger picture

Chapter 2 called the model with a vague history; this chapter makes that call precise and well-ordered. The "stable content first" rule we followed sets up Chapter 5's caching. The project_instructions slot is filled by Chapter 9's memory loader. The skills_summary slot is filled by Chapter 10. The tools list is built by Chapter 6's registry. In other words, this PromptBuilder is the socket that almost every later component plugs into.