# Agent Receipts — provenance is not correctness

"Put it on the blockchain and now it's trustworthy" is one of the most
durable misunderstandings in the space. A chain can prove a handful of things
very well:

- **who** committed to an output (a signature),
- **when** they committed to it (ordering),
- that the bytes **haven't changed** since (integrity),
- **what** was staked or attested behind it.

It cannot, by itself, prove the output is *correct*. Integrity is "these bytes
haven't changed." Truth is "the content of these bytes is right." A hash gives
you the first for free and tells you nothing about the second.

This realm takes that limitation seriously and builds the useful thing that
remains: an append-only log of **execution receipts** whose trust level is
exactly the set of independent attestations they've collected — no more.

## A receipt is commitments, not payloads

```go
type Receipt struct {
	Seq              uint64
	Agent            string  // e.g. a passport agent id
	TaskHash         string  // commitment to the task spec
	InputCommitment  string
	OutputCommitment string
	RuntimeID        string  // which runtime/model produced it
	PolicyVersion    string  // policy in force at execution time
	ToolCallsRoot    string  // root hash over the tool-call trace
	HumanIntervened  bool
	Author           address
	Height           int64
	Attestations     []Attestation
}
```

Nothing here is the actual data. The transcript, the diff, the dataset, the
full tool trace — all of that lives off-chain (content-addressed storage, a
git commit, an artifact store). The chain stores **commitments** to them plus
the lifecycle. This is the sane split: chains are terrible databases and
excellent notaries.

## Validation is a separate, explicit step

A fresh receipt is *unverified by construction*. Its render says so:

> Unverified. This receipt proves the commitment above was made, nothing more.

Independent validators then attach verdicts:

```go
receipt.Attest(cross(cur), seq, receipt.VerdictReproduced, "re-ran, matched")
receipt.Attest(cross(cur), seq, receipt.VerdictTestsPass,  "suite green")
```

Two rules make the attestations mean something:

- **the author cannot attest to their own receipt** — self-attestation proves
  nothing;
- **a validator cannot attest twice** — one identity, one voice.

`Confirmations(seq)` returns `(positive, rejections)` as a raw count, and
deliberately **not** a boolean "is it true." The realm refuses to collapse
independent verdicts into a verdict of its own; the *caller* decides what
threshold it trusts (2-of-3? a specific validator set? a bonded quorum?).
That decision doesn't belong to the log.

## The demo scenario

Three coding agents each fix a failing package and record a receipt committing
to their patch. CI publishes a `tests-pass` attestation; a reviewer agent
publishes `reproduced` or `rejected`. Every receipt — winner and losers —
stays browsable at `:<seq>`, so "why did we ship this patch and not that one"
is answerable months later.

```go
seq := receipt.Record(cross(cur),
	"percy",          // agent
	"task#H",         // task commitment
	"in#H", "out#H",  // input / output commitments
	"claude-opus-4-8",
	"policy-v1",
	"tools#H",        // tool-call trace root
	false,            // human intervened?
)
```

Run the tests:

```sh
gno test .
```

## Honest limitations

- Attestations are only as good as the validators. This realm gives you the
  *structure* for independent verification; it does not solve validator
  Sybil resistance or collusion — that needs bonding, random selection, or a
  jury protocol layered on top.
- Commitments prove integrity, not that the committed artifact was ever
  produced honestly. A receipt is evidence in an audit, not a guarantee.

Which is the whole point: the receipt makes agent actions **auditable and
non-repudiable**, and stops there. Correctness is earned by the attestations,
out in the open, one verdict at a time.

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---

Part of **[moul/gno-contracts](https://github.com/moul/gno-contracts)** — moul's versioned gno.land contracts. See the repository for the full catalog, build/test tooling, and usage.

**Dependency graph:**

![gno.land/r/moul/agents/receipt/v0 dependency graph](https://raw.githubusercontent.com/moul/gno-contracts/main/_assets/gno.land/r/moul/agents/receipt/v0/deps.png)

> ⚠️ **Disclaimer:** provided as-is, without warranty; not security-audited. Full disclaimer: [DISCLAIMER](https://github.com/moul/gno-contracts/blob/main/DISCLAIMER.md).

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