Reading a diff
A diff shows a change rather than a program: red lines went away, green lines arrived, and plain lines are context. You read it for what changed, and for what should have changed and did not.
Agents reformat, re-indent and move code as they go, and a whole-function re-indent can hide a removed check in plain sight. Learning a few ways to cut the noise pays for itself on the first agent-written pull request you read.
Say it to your agent
“Show me git diff --stat main...HEAD first, then git diff -w main...HEAD for src/auth/ only. Tell me which files changed only mechanically, so I can skip them, and say how you know.”