Prompt 3's "what changed since then" field is the underrated one here. One addition worth making: paste the diff of that last change, not a description of it. People describe what they asked for, and the bug is usually in what the agent did beyond that, like the drive-by edit in a file nobody mentioned. With the actual diff in the prompt, the model stops guessing where to look.

A small caveat on Prompt 1, from building an AI app builder myself (disclosure: I work on Mythex): the forbidden-files list works best when it's short. A long list quietly reads as "everything not listed is fair game." Naming the two or three files that must not change, and letting "STOP and ask" cover the rest, tends to hold up better.