Choose the right AI tool for a field rename

You have 3 AI tools: inline autocomplete in your editor, a chat assistant you paste code into, and an autonomous agent that can edit files and run commands across the repo. A task lands: rename the User.fullName field to displayName everywhere, and update all call sites and tests. The codebase is TypeScript, and User objects are read from Postgres and returned by your public API.

Which tool fits, and why are the others the wrong choice? Is any part of this something you would not hand to any of them?