I would have expected people (maybe a small minority, but that includes myself) to have already instructed Claude to do this. It’s a trivial instruction to add to your CLAUDE.md file.
https://code.claude.com/docs/en/settings#attribution-setting...
1. the LLM is instructed on how to write a commit message and never include co-authorship
2. the LLM is asked to produce a commit message
3. the LLM output is parsed by a script which removes co-authorship if the LLM chooses to include it nevertheless> `includeCoAuthoredBy`: whether to instruct the agent to add a Co-authored-by trailer to git commits; defaults to `true`.
This means that, if you don't explicitely configure otherwise, the LLM is specifically instructed to include co-authorship in its higher level instructions.