Signed Inference Receipts

curl https://api.trustedrouter.com/v1/chat/completions \
  -H "Authorization: Bearer $TRUSTEDROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -H "x-inference-receipt: $(openssl rand -hex 16)" \
  -d '{"model":"trustedrouter/auto","messages":[{"role":"user","content":"Hello"}]}' \
  -D - -o response.json

The x-inference-receipt response header holds the compact receipt. Requests without the header keep standard 5.5% pricing and are byte-identical to today. Receipt-enabled managed prepaid requests use the 12% total service fee. Malformed opt-in values are rejected with 400.

from trustedrouter.receipts import verify_receipt

claims = verify_receipt(
    receipt,                      # the inference_receipt object
    request_body=body_bytes,      # exact bytes you sent
    response_stream=wire_bytes,   # exact SSE bytes you received
    expected_nonce=my_nonce,
    max_age_seconds=300,
)
print(claims.model.selected, claims.upstream.tier)

import { verifyReceipt } from "@lore-hex/trusted-router/receipts";

const claims = await verifyReceipt(compactReceipt, {
  requestBody, responseBody,
  expectedNonce: myNonce,
  maxAgeSeconds: 300,
  attestation,   // bytes whose sha256 equals the att_sha256 claim
});

Go, Rust, Swift, and Java expose the same verification with the same checks and the same frozen cross-SDK test vectors. Verification always covers: the Ed25519 signature; rv, iat freshness, and your nonce; the request and response hashes over exact bytes; the receipt event's position in a stream; and the attestation chain with the signing key's commitment checked by set membership.

A failed attested candidate never lends its tier to the fallback that actually serves the response — the tier always describes the connection your bytes used.

Streaming receipts embed the attestation, so nothing extra is fetched and they verify forever from the captured bytes alone. For compact receipts, keys are per-instance and routing is DNS-based, so fetch deterministically: resolve the gateway hostname's A records and ask each instance directly (pin Host/SNI to the hostname while connecting by IP) for its /receipt-key until the kid matches — polling the hostname is a lottery that can miss instances behind connection reuse. The key log covers keys after their instance is gone.

Archive the attestation with the receipt. If a receipt matters to you — an audit trail, a dispute, an eval run — store the matching attestation document (and for streams, the captured wire bytes) next to it at verification time. That bundle verifies offline forever with no dependency on TrustedRouter, the signing instance, or the key log being reachable.