A GitHub deploy key writes to one repo and nothing else, and GitHub's API can make one (a fine-grained token needs a person in the browser). The key is written 0600 in the run's temp folder; github.com's published host keys are built in and other hosts need theirs in known_hosts, so nothing is trusted on first use. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_017K4vyY3yUD3GsvoZaAtKkD