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

# Provable verdicts

> How every verdict is made tamper-evident, attested, permanent, and independently verifiable — and how you check it yourself.

A verdict is only worth as much as your trust in whoever produced it — unless it's **provable**. Every Chance verification carries a receipt that anyone can re-check from scratch, trusting no one in the middle. Not "trust our dashboard" — recompute every claim in your own browser.

## Four stages

<Steps>
  <Step title="Run — the flight recorder">
    As the judge works, every step is appended to an append-only **hash chain**. Change, delete, or reorder one byte and the final root changes completely. The chain head — the **transcript root** — commits to the entire decision.
  </Step>

  <Step title="Run + Sign — inside the enclave">
    The whole judge loop — **the model call to OpenRouter, the transcript hash chain, and the signature** — runs inside a hardware-isolated **SEV-SNP enclave (a TEE)**. The judge key is released to the enclave and never leaves it; the signed digest binds the run, its transcript root, its output, **and the enclave's own code measurement**; and each signature ships with a Microsoft Azure Attestation (MAA) token. So a valid receipt proves *this exact measured code made the model call and produced this verdict* — not merely that someone signed it.
  </Step>

  <Step title="Anchor — the public record">
    The signed commitments are written to a **public blockchain** (`RunRegistry` on Base). The record includes the enclave measurement, so the onchain anchor itself attests *which measured code held the signing key* — permanent, timestamped, and neutral.
  </Step>

  <Step title="Verify — don't trust, recompute">
    Anyone re-derives every claim from the published transcript, **in the browser**: recompute the hash chain, recover the signer, RS256-verify the MAA attestation against Microsoft's live keys, and ask the chain whether the commitments are anchored. No trust in Chance is required at any step.
  </Step>
</Steps>

## The attestation is verified, not asserted

The browser check isn't a badge we render — it's a real cryptographic verification you can read and reimplement:

* **Signature.** The MAA token is RS256-verified against Microsoft's published signing keys (fetched live from the attestation service — CORS-enabled, so the browser does it directly, no Chance server in the loop).
* **Hardware + code.** The token must attest a genuine, non-debuggable **AMD SEV-SNP** enclave whose code measurement (`x-ms-sevsnpvm-hostdata`) matches the expected, published value — pinning *which* code held the key.
* **Binding.** The measurement is committed into the judge-signed digest and stored onchain, so the anchor and the attestation agree on the same enclave.

A hand-crafted token, a valid token from a different attestation service, or one whose measurement doesn't match all fail — visibly.

## What the receipt contains

Every verdict response includes a `proof` object:

<ResponseField name="transcriptRoot" type="string">
  Root of the hash-chained transcript of the whole run.
</ResponseField>

<ResponseField name="signature" type="string">
  The judge's signature over the run digest.
</ResponseField>

<ResponseField name="judge" type="string">
  The judge address that signed.
</ResponseField>

<ResponseField name="hostdata" type="string">
  The attested enclave code measurement bound into the digest and the onchain record.
</ResponseField>

<ResponseField name="attested" type="boolean">
  `true` when the judge key ran inside an attested TEE.
</ResponseField>

<ResponseField name="anchorTx" type="string">
  The onchain anchor transaction (with an explorer link).
</ResponseField>

<ResponseField name="transcriptUri" type="string">
  URL of the full transcript. Owner-only: authenticate as the run's account
  (API key via `x-api-key`, or signed in in the browser) — the URI is committed
  into the public onchain anchor, so the URL itself grants nothing.
</ResponseField>

## What is and isn't guaranteed

<Note>
  Chance proves the decision is **tamper-evident**, that the **model call and the signing happened inside genuine measured enclave hardware** — the receipt proves *this exact code produced this verdict* — and that the **measurement is anchored onchain**, all checkable by you, trusting no one. Two honest limits: it does not prove the decision was *wise* (garbage in, provable garbage out — the intent you submit is what's being checked against), and it **trusts the model provider** — the enclave proves it made the call and committed the exact response it received, not that the provider didn't quietly serve a different model.
</Note>