Agent An autonomous AI program acting for a user or system. Within HoodLayer, the agent is the party that holds a wallet and pays for services.

Allowance An on-chain grant that lets a service (the grantee) spend from an agent’s wallet (the granter) up to a hard cap. There’s no fixed billing interval as with subscriptions; the grantee draws funds down as it needs them. See Allowances.

Billing cycle How often a subscription gets charged. Set by the Plan’s interval field: monthly, weekly, daily, or per-request.

Collection The provider pulling funds from a subscriber’s wallet at the close of a billing cycle. The Subscription Authority authorizes it, and the HoodLayer Subscriptions contract carries it out.

Facilitator The off-chain piece that checks payment headers and submits transactions to Robinhood Chain. HoodLayer runs it as a centralized service during beta; after beta it becomes a permissionless network of staked operator nodes. See Facilitator Network.

Grantee The service or wallet an Allowance authorizes to spend the granter’s funds.

Granter The agent wallet that sets up the spend cap in an Allowance.

MPP (Machine Payments Protocol) An open standard on the IETF track for machine-to-machine payments over HTTP, published by Stripe and Tempo in March 2026. Agents that speak MPP are meant to work with HoodLayer out of the box. See MPP Compatibility.

Payment gate Middleware (hoodlayer.paymentGate()) that catches unauthenticated requests to a service API and replies with a 402 Payment Required response carrying the payment terms.

Payment proof A signed object the Facilitator returns once an on-chain payment succeeds. It travels in the X-PAYMENT request header when the request is retried, and the service checks it before serving the resource.

Payment session A short-lived token authorizing a burst of requests against a balance committed up front, settled periodically in batches. Built for high-frequency agents. Arriving in general availability. See Payment Sessions.

Plan A pricing record a service provider publishes on-chain to the HoodLayer Plan Registry. It sets the price, billing interval, token, and an optional trial period for a service, and can’t be changed after creation. See Plans.

Plan Registry The catalog on Robinhood Chain mainnet where service providers publish their Plans. Any Robinhood Chain client can read it.

Provider A service or API that takes payments from agents through HoodLayer. Providers create plans, put the payment gate in front of their API, and collect from subscribers.

HoodLayer SDK (@hoodlayerorg/sdk) The TypeScript library that wraps all protocol and on-chain interactions, covering both agents (HoodLayerAgent) and providers (HoodLayerProvider).

Subscription An on-chain record tying an agent wallet to a Plan, with billing delegation authorized. It lets recurring billing run automatically, no per-transaction signature from the agent required. See Subscriptions.

Subscription Authority The delegation an agent grants when subscribing. It lets the service provider pull up to the authorized amount each billing cycle, with enforcement by the HoodLayer Subscriptions contract on-chain.

Token A fungible ERC-20 token on Robinhood Chain. USDC and USDT on Robinhood Chain both qualify. All HoodLayer payments use these tokens.

Trial period An optional free stretch at the start of a subscription, set in the Plan. Nothing gets collected while a trial runs; the first billing cycle starts once it ends.

USDC USD Coin, Circle’s regulated US dollar stablecoin. During beta it’s HoodLayer’s primary payment token. Address on Robinhood Chain mainnet: 0xecdda8f70c0880d915f746c861ace5dd58721a74. 6 decimal places.

Webhook An HTTP POST that HoodLayer sends to an endpoint you configure whenever a payment lifecycle event happens (subscription renewed, payment failed, allowance depleted, and so on). See Webhooks.

x402 An HTTP-native payment protocol describing how servers signal that payment is required and how clients attach payment proofs. Coinbase originated it in May 2025; the x402 Foundation under the Linux Foundation now governs it. On Robinhood Chain, HoodLayer is a first-class x402 implementation. See x402 Compatibility.