All sorts of efforts that used to be put off indefinitely can now be handled largely by LLMs. Yesterday I took a codebase (~50 source files) and spawned a sub-agent (GLM 5.3 Flash) for every single file. Each file was analyzed for test coverage issues, inconsistencies between comments and implementations, and all call sites against the implementation. Then issues were aggregated. I reviewed the list manually, had Opus and K3 review as well to prune the list, and then had a commit made for every minor issue found. 70 commits with maybe 30 minutes of manual work.

Not exactly a refactor, but high degrees of consistency are what I strive for in a codebase. LLMs get confused by inconsistencies, as do humans.