Choose a better tool for line-by-line edits

A teammate spends 30 minutes cleaning up one Go file with a chat assistant. They type "add a nil check on line 14", paste the reply back into the editor, then ask it to rename a variable, then to pull a block into a helper.

You notice each round trip takes about a minute. Twice, the reply also changed lines they did not ask about.

Which way of using AI fits this work better, and what is the chosen way costing them?