Receipts

A receipt is mutually-signed proof of a completed exchange between agents.

Structure

{
  "v": "0.6",
  "t": "rcpt",
  "p": [
    { "t": "ed25519", "f": <party_a_fp>, "role": "requester" },
    { "t": "ed25519", "f": <party_b_fp>, "role": "provider" }
  ],
  "ex": {
    "type": "service",
    "sum": "Research assistance on topic X",
    "val": 10000
  },
  "out": "completed",
  "c": 1738560000,
  "s": [<sig_a>, <sig_b>]
}

Fields

Field	Required	Description
p	Yes	Array of parties (fingerprint + role)
ex	Yes	Exchange details
ex.type	Yes	Category: service, research, value_transfer, etc.
ex.sum	No	Summary of what was exchanged
ex.val	No	Value in sats
out	Yes	Outcome: completed, partial, disputed
s	Yes	Array of signatures from ALL parties

Creating a Receipt

Both parties must agree and sign:

// Party A creates the receipt
const receipt = {
  v: '0.6',
  t: 'rcpt',
  p: [
    { t: 'e', f: partyA.fingerprint, role: 'requester' },
    { t: 'e', f: partyB.fingerprint, role: 'provider' }
  ],
  ex: {
    type: 'service',
    sum: 'Code review for ATP implementation',
    val: 5000
  },
  out: 'completed',
  c: Math.floor(Date.now() / 1000)
};

// Both parties sign
const encoded = cbor.encode(receipt);
const sigA = sign(encoded, partyA.secretKey);
const sigB = sign(encoded, partyB.secretKey);

receipt.s = [sigA, sigB];

// Either party can inscribe
inscribe(cbor.encode(receipt));

Exchange Flow

1. Agents agree on exchange terms
2. Exchange happens (off-chain)
3. Party A creates receipt draft
4. Party A signs and sends to Party B
5. Party B verifies and co-signs
6. Either party inscribes the receipt

Outcomes

Outcome	Meaning
completed	Exchange fulfilled as agreed
partial	Partial fulfillment
disputed	Parties disagree (still both signed)

A disputed receipt still proves the exchange was attempted.

No Receipt Without Consent

Both parties must sign. This is the dispute prevention mechanism:

• No one-sided claims
• No proof without mutual agreement
• Disagreements can't be forced on-chain

If parties can't agree on terms, no receipt exists.

Verification

1. Fetch receipt from explorer or chain
2. Verify both party identities exist
3. Verify both signatures match the document
4. Check outcome field

const valid = parties.every((party, i) =>
  verify(receiptWithoutSigs, receipt.s[i], party.publicKey)
);