Comment by tacone

Also for future reference, Copilot - specifically - includes a configuration flag to toggle the co-authorship (see `copilot help config`):

> `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.