1 min lesson
Context, indexing and retrieval
Rebuild the parts of "Context, indexing and retrieval", then say why each one matters.
Step 1 of 3
The model only knows what made it into the context window. That window is small, expensive and filled by the harness from a repo far larger than it.
This one mechanism explains the most common developer complaint about coding agents: why didn't it use my other file? Teaching it well retires a whole category of support questions.