Start with the thing an agent actually produces.
Source code
The text of a program, written by a person or an agent and saved in ordinary files. It is a precise set of instructions. The computer does what the text says, which is not always what its author meant.
Source code is what an agent hands you and what you answer for. It can read perfectly sensibly and still be wrong, so you judge it by what it does when it runs, not by how confident it sounds.
Say it to your agent
“For each file you changed, show me the lines that changed and tell me what they do when they run. Don't summarise what you meant them to do.”