Cursor or Claude Code for the old and incomplete codebase? How was my decision made

I have another project where there are three years of decisions made on layers, two refactors that never saw the light of day, and a misc directory that I dare not open. Last month I deliberately tried Cursor and Claude Code on it for two purposes.

For deciphering the mess, the terminal agent proved superior. It told me why a background task executed twice and tracked down the problem through five files without my even looking at any of them. For minor changes in user interface, the editor was superior since inline diffs allowed me to accept one line and reject the next.

So I currently use the agent for exploration and the editor for polishing, even though it is not easy to switch back and forth. In any case, both are bad at what the other does well.

Of course, this doesn't apply to everyone. I work on a Rails application with a single developer, while your mileage will vary if you work on a large monorepo or on a typed frontend.

What codebase characteristics or configuration led you to prefer one solution over the other? Have you seen a configuration where a single tool did both?