> ## Documentation Index
> Fetch the complete documentation index at: https://docs.algovoi.co.uk/llms.txt
> Use this file to discover all available pages before exploring further.

# Offline-Verifiable Agent Receipts

> An offline-verifiable agent payment receipt recomputes from its own preimage with RFC 8785 (JCS) and SHA-256, with no network, no issuer, and no service call.

An **offline-verifiable agent payment receipt** is one that a third party can check without contacting the issuer, the sender, or any online service. AlgoVoi authored the canonicalisation discipline that makes this hold: pin [RFC 8785 (JCS)](https://www.rfc-editor.org/rfc/rfc8785) as the preimage form, hash with SHA-256, and every receipt recomputes from its raw fields on any machine, fully offline.

## Offline means no service call

A receipt carries its own fields. A verifier canonicalises those fields under JCS, hashes the bytes with SHA-256, and compares the result to the receipt's `content_hash`. If they match, the receipt is intact and authentic to its preimage. If a single field changed, the hash diverges and the tamper is detected.

Nothing in that loop touches the network. The verifier needs a JSON parser, a JCS implementation, and a SHA-256 function, all of which ship in standard libraries. There is no issuer endpoint to call, no registry to resolve, and no AlgoVoi runtime in the trust path.

Because the rule is pinned in-band as `canon_version: jcs-rfc8785-v1`, a receipt retained for a statutory period re-verifies under the exact rules it was issued under, with no dependence on an external rule registry that may have moved or changed.

## Proven without AlgoVoi's code

The published values are not an artefact of AlgoVoi's canonicalizer. The conformance corpus ships a first-principles check that rebuilds the JCS bytes by hand and hashes them with stdlib SHA-256 only:

```bash theme={null}
git clone https://github.com/chopmob-cloud/algovoi-jcs-conformance-vectors
cd algovoi-jcs-conformance-vectors
pip install algovoi-substrate
python composition/first_principles_check.py
# FIRST-PRINCIPLES RESULT: 11/11 checks PASS ... No AlgoVoi canonicalizer was invoked
```

The same construction is directly executed across eight independent reference implementations (Python, TypeScript, Go, Rust, Java, PHP, .NET, Ruby) at 880/880 cumulative agreements, including the RFC 8785 author's own Java implementation. Eight implementations that share no code agreeing on the same bytes makes the result a property of the standard.

## Which receipts are offline-verifiable

Every receipt in the AlgoVoi lifecycle recomputes the same way, because they all anchor to one canonicalisation pin:

| Receipt                                           | Records                                                  |
| ------------------------------------------------- | -------------------------------------------------------- |
| [Compliance receipt](/compliance-receipt)         | Admission-time screening decision                        |
| [Settlement attestation](/settlement-attestation) | Settlement state on a given chain                        |
| [Refund receipt](/refund-receipt)                 | Refund outcome, chained to settlement                    |
| [execution\_ref](/execution-ref)                  | Executed action bound to the decision that authorized it |

A verifier walking the chain confirms admission, settlement, and refund under a single byte-deterministic discipline, offline.

## Do it yourself

```bash theme={null}
git clone https://github.com/chopmob-cloud/algovoi-jcs-conformance-vectors
cd algovoi-jcs-conformance-vectors
pip install algovoi-substrate
python composition/verify_corpus.py
# ALL RUN SETS + COMPOSITION KEYSTONE REPRODUCE BYTE-FOR-BYTE
```

Each vector set also ships a `runner_node.js` alongside its `runner_python.py`, both checking the same expected hashes, so a pass in each language is byte-for-byte Python and TypeScript parity rather than two separate claims.

## Specification and authorship

The discipline is AlgoVoi-authored and specified in IETF Internet-Draft [`draft-hopley-x402-canonicalisation-jcs-v1`](https://datatracker.ietf.org/doc/draft-hopley-x402-canonicalisation-jcs-v1/), identified by `urn:x402:canonicalisation:jcs-rfc8785-v1`. Reference implementations are Apache-2.0: [`algovoi-substrate`](https://pypi.org/project/algovoi-substrate/) and [`@algovoi/substrate`](https://www.npmjs.com/package/@algovoi/substrate).

## See also

* [Verify it yourself](/verify-it-yourself) — reproduce the full corpus offline
* [Verifiable x402 receipts](/verifiable-x402-receipt) — the x402 receipt set
* [No-PII compliance receipts](/no-pii-compliance-receipt) — screening evidence with no personal data
* [Conformance vectors](/conformance-vectors) — the cross-implementation matrix
* [Substrate authorship and provenance](/substrate-authorship-provenance) — citable AlgoVoi authorship record