The current ledger tip as a freshly signed checkpoint, for an external anchoring submitter to commit

Responses

• 200
  { signed: { payload, keyId, signature }, signingInput } — `sha256(signingInput)` is the exact 32 bytes an on-chain commitment holds. Never cached: `payload.at` is minted per call
• 404
  Anchor signing is not configured, or the ledger is empty — nothing is claimed to be anchorable yet