Retrieval, chunking and evaluation from first principles. You will spend more time reading and steering generated code than typing it, which is how this work is actually done now.
Answering from your own documents
Why a model needs your pages handed to it, and how they get found.
Picking the right pieces
How many pages to grab, and how to rule out the wrong ones first.
Knowing whether the search got worse
Measure it, so a bad change cannot hide behind a good demo.
Putting it in front of people
What breaks once real questions arrive, in real wording.