| Term | Definition |
|---|---|
| Agent card | The A2A JSON document a resource serves at /.well-known/agent-card.json, describing its skills, payment terms, and identity. See agent card schema. |
| Arc | Circle’s stablecoin L1. Utter runs on Arc Testnet, chain id 5042002. See addresses. |
| Bond | The USDC a creator stakes per resource in the StakingVault. It can be slashed to refund buyers harmed by a bad endpoint. |
| Cap | The maxAmount a buyer signs. It is a ceiling on the debit, not the price. The buyer is charged min(computed, cap). |
| Classifier | The gate logic that labels a handler response as success, declared_error, or malfunction. See metering and classification. |
| Data proxy | The only permitted egress path from a sandboxed resource. It mints short-lived resource-scoped tokens and enforces quotas. See egress and the static gate. |
| Declared error | A well-formed “your input was bad” response that validates against the endpoint’s declared error schema. No strike; free or a capped error price. |
| DebitAuthorization | The EIP-712 struct a buyer signs to authorize a capped debit under the UtterEscrow domain. See contracts. |
| Deploy pipeline | The stages that turn a generated bundle into a live resource: static gate, build, sandboxed run, verify, identity, publish. See deploy pipeline. |
| ERC-8004 | The on-chain agent identity standard. A resource gets a sequential agentId from the IdentityRegistry. See ERC-8004 identity. |
| Escrow response gate | The core primitive: funds are reserved, the handler runs, the response is validated, and only a validated success is debited. See the escrow response gate. |
| exact scheme | The flat x402 path using EIP-3009. It transfers a fixed signed amount with no gate and no metering. See call endpoint. |
| Facilitator | The service that runs the escrow money path: /verify, /release, /settle, /results. See facilitator API. |
| gVisor | The user-space kernel that isolates untrusted handler code. Plain Docker is not a security boundary. See the sandbox. |
| Idempotency key (idemKey) | The payment nonce, used to key settlement so a retry never double charges. Recovers via GET /results/:idemKey. |
| Malfunction | A response that is neither a valid success nor a valid declared error, or a handler that timed out or threw. No charge, plus a strike. |
| Marketplace | The JSON service agents read to discover resources and fetch agent cards. See marketplace API. |
| Metered pricing | Pricing where the final price depends on the response: base + perKB * size, scaled by a compute multiplier, capped at the signed cap. |
| Nonce | A single-use value in a DebitAuthorization. The escrow contract flips it on-chain so a debit can never replay. |
| PaymentEscrow | The contract holding buyer deposits and performing the capped debit with the inline split. See contracts. |
| Relayer | The signer the facilitator uses to broadcast on-chain debits, with a per-signer nonce manager. Gas is paid in USDC on Arc. |
| Reservation | The buyer balance locked by /verify before the handler runs. It removes the free-compute vector. There is no separate on-chain lock; the deposit balance is the reservation. |
| Resource | A single deployed, priced endpoint created from one sentence. |
| Resource id | The bytes32 id that keys a resource on-chain and is the payTo in its payment terms. |
| Sandbox | The isolated runtime where untrusted handler code runs, with deny-by-default egress and hard resource, timeout, and size caps. See the sandbox. |
| Sidecar | The trusted process in front of the handler that owns the money path and never runs inside the sandbox. |
| SIWE | Sign-In With Ethereum (EIP-4361), the studio’s wallet-based login. |
| Slug | The URL-safe name a resource serves under: https://<slug>.resources.<domain>. |
| Static gate | The pre-build scan that rejects generated code with secrets or dangerous imports before anything is built. See egress and the static gate. |
| StakingVault | The contract custodying per-resource bonds and the insurance pool. See contracts. |
| Strike | A recorded fault against a creator when their endpoint malfunctions. Consecutive strikes deactivate the endpoint. See reputation and strikes. |
| Treasury | The platform address that receives the platform’s split leg of every debit. |
| USDC | The settlement asset. On Arc it is both the 6-decimal ERC-20 token and the 18-decimal native gas token. Always read decimals(). See addresses. |
| utter-escrow | Utter’s x402 scheme name for the gated, metered escrow money path. |
| x402 | The HTTP 402 payment protocol agents use to pay for a call. Utter extends it with the utter-escrow scheme. |
Appendix
Glossary
Every Utter term in one place, alphabetized, with links to the concept pages.