Receipts

Receipt contents, delivery, and the limits of what a receipt proves.

Prove / receipts

Provn returns a receipt for each metered call. The gateway writes a canonical JSON payload, encodes it as base64url and signs the payload with secp256k1 using EIP-191 personal_sign.

Delivery

Call	Location
Chat completion or sandbox run	`x-provn-receipt`, `x-provn-receipt-sig` and `x-provn-receipt-signer` headers
Streamed chat completion	An `event: provn.receipt` event with `{receipt, signature, signer}`, sent before `data: [DONE]`
Terminal run	The response, and `GET /v1/receipts/:id` for anyone

Payload

json

{
  "v": 1,
  "kind": "inference",
  "request_id": "req_4tQ8...",
  "run_id": "run_9Kd2...",
  "prev": "3f9c...e1",
  "content_fingerprint": "9b1c4e0f2a7d6c31",
  "model": "provn",
  "engine": "gpt-oss-20b",
  "units": { "prompt_tokens": 12, "completion_tokens": 48 },
  "cost_micro_usd": 21,
  "key_id": "key_7Hc...",
  "status": "ok",
  "logging": "metadata-only",
  "chain_id": 4663,
  "issued_at": "2026-09-16T12:00:00.000Z"
}

Field	Meaning
`v`	Payload version, `1` for this format.
`kind`	`inference`, `sandbox` or `terminal`.
`request_id`	Matches the `x-provn-request-id` header.
`run_id`	The run the call joined through `x-provn-run`.
`prev`	SHA-256 (hex) of the previous receipt payload in the run, `null` on the first.
`content_fingerprint`	First 8 bytes (16 hex characters) of SHA-256 over the request. Inference hashes the JSON body with sorted keys, and sandbox and Terminal hash the submitted code.
`model`	The id you called.
`engine`	The upstream model that served it.
`units`	`{prompt_tokens, completion_tokens}` for inference, `{cpu_ms, mem_limit_mb}` for sandbox and Terminal.
`cost_micro_usd`	The amount billed, in millionths of a dollar.
`key_id`	The key that paid, `null` for Terminal runs.
`status`	`ok`, `error`, `timeout` or `cap_reached`. Failed sandbox runs add `error_class`.
`logging`	`metadata-only`.
`chain_id`	`4663`, Robinhood Chain.
`issued_at`	ISO 8601 time from the gateway clock.

Your receipts are private. Turn on sharing for one in the dashboard and anyone can fetch it at GET /v1/receipts/:id. Terminal receipts start public.

What a valid receipt shows

The holder of the published signer key issued this exact payload, and nobody edited it afterwards.
The gateway metered the call under that key, model and engine, and charged the stated cost.
A request you still hold matches the fingerprint, once you hash it and compare.

What it does not show

That the model's answer is correct.
The work the upstream host did on its own hardware. Provn records the engine it routed to and can't attest beyond that.
A time other than the gateway's own clock, unless the receipt sits in an anchored batch.

Receipts

Delivery

Payload

Sharing

What a valid receipt shows

What it does not show