main requires signed commits, so the pull request the bump job opens after a
release cannot be merged while the commit in it is unsigned. The key the server
signs merge commits with is not reachable from a runner, so the job signs with a
dedicated release-bot SSH key that the instance trusts through
TRUSTED_SSH_KEYS — no bot account, because an account key is only consulted
after the web Verify flow and that flow has no API.
Inert until the key is trusted and RELEASE_BOT_SIGNING_KEY is set, and loudly so:
the step checks the secret and ssh-keygen before it starts, runs the key through
ssh-keygen -y so a truncated or re-wrapped one is caught as itself rather than as
"gpg failed to sign the data", and the commit is re-read for a gpgsig header
before it is pushed.
Co-Authored-By: Claude Opus 5 <[email protected]>
