Nothing stops someone from committing secrets to public repos, with or without AI. Unless guardrails are put in place that scans repos before push, and only people already wary of secrets leaking would setup said guardrails in the first place.

The file is .gitignored if Claude creates it - any commits by Claude would be due to someone overriding that or creating it themselves incorrectly.

None of this has anything to do with open vs. closed source.

Of course an open source harness can put secrets into a commit.

Humans do it!