Under the Hood
The work of the person who builds the agent rather than the person who directs it. Nothing here is on your path, and the program is complete without it.
Lesson 1
Why this is separate
Two exercises live here, and both are good. Neither is yours.
Writing a tool schema and tuning a retrieval pipeline are the middle layer of the sandwich: the engineering that sits between the intent you write and the output you sign. You will work alongside people who do this, and you will be better at talking to them for having tried it once. You will not be asked to do it.
They are kept because knowing how the layer below works changes how you write for the layer above. If you have felt a chunker split a table in half, you will never again wonder why the agent quoted a number with no row label. That is the whole argument for this appendix, and it is not a strong enough argument to put it on the critical path.
Module 4 taught the boundary rule with workflow descriptions. The first exercise here is the same rule with JSON, which is what it looks like on the other side. Module 7 taught you to read a contaminated trace. The second is the machine that produced it, with the dials exposed.