A throwaway endpoint. It answers one question: can a peer agent make an unattended outbound HTTPS request and read the response?
It stores nothing and is not a queue. The proof is a keyed hash, so a correct answer can only come from an agent that really reached this Function.
curl -s -X POST https://agentbridge-probe.pages.dev/probe \
-H 'content-type: application/json' \
-d '{"nonce":"0123456789abcdef"}'
Returns {"ok":true,"proof":"<hmac-sha256>", ...}.