Protocol Overview

How AMP works under the hood.

AMP is a financial state protocol. Instead of processing a payment per request, it maintains a persistent financial relationship between two parties through an on-chain channel.

Payment flow

Client requests a resource — GET /v1/data with no payment headers
Server returns pricing — 402 Payment Required with AMP-Pricing, AMP-Recipient, AMP-Program headers
Client opens a channel — one Solana transaction deposits funds into a PDA-owned vault
Client retries with credentials — AMP-Channel, AMP-Seq, AMP-Sig headers
Server validates and serves — verifies channel state, signature, and sequence number. Returns 200 OK
Repeat — steps 4-5 for all subsequent requests. Zero on-chain transactions.
Server settles periodically — one Solana transaction covers all accumulated usage
Client closes channel — remaining balance is refunded

Core concepts

Channels

A persistent financial state object between a funder and recipient, stored as a PDA on Solana. Holds deposited tokens in a vault. Lifecycle: Open, Active, Settled (repeating), Closed.

Metering

Off-chain usage tracking by the server. Modes: per-call, per-second, per-byte, per-compute. No on-chain transactions during consumption.

Settlement

On-chain transfer of owed funds from the vault to the recipient. Always net — one transaction covers all usage since the last settlement.

Delegation

A funder assigns consumption rights to a delegate pubkey. The delegate can consume services against the channel up to a specified limit.

Error codes

Code	Description	HTTP Status
`AMP_NO_CHANNEL`	No valid channel for this request	402
`AMP_UNDERFUNDED`	Channel balance below minimum	402
`AMP_CLOSED`	Channel has been closed	410
`AMP_RATE_EXCEEDED`	Usage exceeds channel rate limit	429
`AMP_INVALID_SEQ`	Sequence number not monotonically increasing	400
`AMP_INVALID_SIG`	Signature verification failed	401
`AMP_SETTLE_EARLY`	Settlement attempted before interval elapsed	425
`AMP_DEPOSIT_LOW`	Initial deposit below server minimum	400
`AMP_INVALID_PROOF`	Metering proof signature invalid	400

Transports

AMP is transport-agnostic. Defined bindings for:

HTTP — headers on every request
MCP / JSON-RPC — _amp credentials in tool calls
WebSocket — JSON or binary frame prefix
gRPC — metadata keys