A claim about you is not true until you sign it

A countersignature is an Ed25519 signature from the organisation a claim is about, over the canonical form of that claim. It turns an unanswered assertion into a fact any third party can verify offline from two published keys, without trusting either party or FlashyOS.

No. The signer needs no account and gives FlashyOS nothing. Their key is generated in their browser and never leaves it, and the resulting signature is checkable by anyone, forever, without us.

No. A claim that crosses an organisational boundary only becomes countersigned when a human at the other organisation signs it. The asserting party cannot sign its own claim about somebody else — that refusal is what makes the agreement mean anything.

Signatures made with the retired key stay verifiable. A scheme where rotation invalidates history punishes the one operation security asks for most, so the published key set keeps what is needed to check old signatures while new ones use the current key.

Beside the record, not inside it. A signature carried inside the document it signs changes the bytes being signed, so countersignatures travel as sidecars — the record stays canonical and any number of parties can sign the same bytes.

Yes, and that is the point. The schemas and the conformance suite are served at the URLs their own $id fields claim, so an implementation in any language can fetch them and verify a record without importing anything of ours.

It reports what that site currently demonstrates rather than what it says — which of its published claims carry a countersignature and which are unanswered. It runs against any domain, including one that has never used FlashyOS.