I've been in a similar position; where I was tasked to refactor a messy LARGE codebase that was created by a bunch of different previous team members. Here's what I would recommend:
- If your codebase contains sensitive or IP related code make sure to remove that before interacting with your AI assistant of choice
- Upload the repo/codebase to Claude Code (or codex or whatever you prefer); and ask it to analyse it: the good, the bad and the ugly
- Based on the analysis ask the AI assistant to create an .md file with all recommendations/optimisations required to improve code (make sure to have all relevant tests included in the refactoring loop)
- Note the before outcomes/outputs; do the refactoring using Claude Code again or whatever tool you prefer; then check after outcomes/outputs to make sure nothing did break
Usually it's an iterative process; if done correctly you could end up with a much better codebase.
Good luck!
Usually it's an iterative process; if done correctly you could end up with a much better codebase. Good luck!