Prompt
Everything sent to the model in one request: system prompt, tool definitions, earlier messages, file contents and your latest words. In everyday speech it means only what you just typed, which is usually a small part.
Most of what shapes an agent's output isn't what you typed this turn. When output goes wrong, look at the whole of what was sent before you reword your sentence.
Say it to your agent
“Before you start, tell me which files you have read for this task and which you haven't. Then read src/cart.ts and src/cart.test.ts, and nothing else yet.”