Pointing at examples
Also called Prior art
Telling the agent to copy something that already exists: "follow the pattern in src/db/users.ts". One path, and the code does the explaining. It is about the cheapest useful context there is.
Left alone, an agent writes what was common in its training text and not what is common in your repo. A pointer settles naming, errors and test layout in one line. It also copies the flaws, so point at the file you would want more of.
Say it to your agent
“Add a GET /api/orders route. Copy the structure of src/api/users.ts: same validation, same error shape, same test layout as src/api/users.test.ts. Tell me anything you had to do differently, and why.”