What a proof_loop_do receipt records
A proof_loop_do receipt is one AER-1 record (receipt schema version 0.4, hosted profile zambo-hosted-receipt/1) for one call. Read from a real proof_loop_do payload, it records:
- Receipt id: a full UUID. The id is the address of the record: the human page is https://zambo.dev/run/ followed by the id.
- Tool: name
proof_loop_do, version4.0.0, scopepublic. - Timestamps: the record creation time, and inside the step list a started_at and a completed_at for the call itself.
- Step status: one step per call, with the tool name and its status. On the first example below the step status is
success. - The saved output: the exact output object the call returned, kept as canonical bytes. The saved output carries schema, type, label, ai, check, an observation_commitment and an observation_note, the same observation shape the check step reads.
- Output digest: output_hash, the SHA-256 digest of those canonical bytes, with the canonical byte length recorded too (804 bytes on the first example below).
- Caller and provenance: a caller type (
sessionon the first example) and a provenance class ofLOGGED BY AGENT, which states how the record was produced. - Declared side effects: the record declares its side effects,
noneon the first example. - Verification status: the API carries a verification_status field for the record. On the first example below, the verify API reported verification_status
commitment_matches, its wording for a record whose digest still matches the saved bytes.
Live proof_loop_do receipt examples
Each example below is a real proof_loop_do receipt. Open one and you see the saved result, when it was saved, and its digest, the same fields described above.
zambo.dev/run/dcb89089-ec96-481a-b62b-eb06883e167f
Saved: 2026-10-24T13:53:20.019Z
Output SHA-256 digest: sha256:a6d02b795bbf45d11af4b76fc2fe489b5490f276eeedbd64b885248ad47745e3
Checked live on 2026-10-24: this URL returned HTTP 200 with this receipt on the page.
zambo.dev/run/40998bd4-2bad-4236-bb9c-e8d1bdb4f05c
Saved: 2026-10-24T04:45:13.341Z
Output SHA-256 digest: sha256:a085fa4f6d919151e13a3f3b9e373b24a4cbe5a1a50387f9005a3a66cf4175fc
Checked live on 2026-10-24: this URL returned HTTP 200 with this receipt on the page.
zambo.dev/run/18ca7b35-787a-44ff-bbfc-0ef71077b9ad
Saved: 2026-10-24T04:45:12.530Z
Output SHA-256 digest: sha256:8d37b1ed3819dc93ca554f264cca7b5af0c57f2bcfc68c3de49f3b7dcc6b1fdd
Checked live on 2026-10-24: this URL returned HTTP 200 with this receipt on the page.
How to verify a proof_loop_do receipt
- Open zambo.dev/verify/ and paste the receipt link or the receipt id. The checker recomputes the SHA-256 digest over the saved bytes and reports whether the record still matches.
- Or call the API directly:
GET https://zambo.dev/api/v2/receipt/{receipt-id}/verifyreturns the record as JSON, including its output_hash and verification_status. - The format is AER-1, an open IETF Internet-Draft: draft-zambo-aer1-26. Anyone can implement the check; it does not need a Zambo account.
Verification answers one question: is this the record that was saved, byte for byte? It does not answer whether the result inside was right.
Get receipts for your own calls
Add Zambo to your AI once, at zambo.dev/add/, and every tool call after that files a receipt like the ones above. Every account starts with 20 free calls per day, and free calls file receipts too. The background is at AI agent receipts, and more worked examples are indexed at receipt examples by tool.