Overview

Valeo Stratum is a clearing and settlement layer for x402 AI agent payments. Facilitators submit verified payments to Stratum. Stratum batches them into 60-second windows, computes multilateral netting, and executes USDC settlements on-chain automatically.

Stratum solves the problem Stripe identified in their 2025 Annual Letter: current blockchains cannot handle the 1M–1B transactions per second that AI agents will generate. Rather than building a new blockchain, Stratum applies the same clearing/netting model that traditional finance has used for decades (DTCC, CLS Bank, Visa) to compress millions of logical transactions into minimal on-chain settlements.

What Stratum Does

1. Accepts payment instructions. Facilitators submit verified x402 payments via POST /v1/settle/submit. Stratum records each as a signed receipt.
2. Batches and nets. Every 60 seconds, Stratum closes a settlement window and computes multilateral netting across all counterparties. 10,000 bilateral payments collapse into ~50 net transfers.
3. Settles on-chain. Stratum executes USDC transfers on Solana and Base from its own settlement wallet. Each payment is tracked with an on-chain txHash as proof.
4. Anchors Merkle proofs. A Merkle root covering every receipt in the window is anchored on Solana for public verifiability.

Architecture

The system flow:

Agent → Facilitator (verifies x402 payment) → Stratum (netting + settlement) → Chain (Solana/Base)

Stratum sits behind the facilitator, not in front of the agent. The facilitator verifies the x402 payment (signature check, amount check, etc.), then submits it to Stratum for batched settlement.

Core Components

Stratum Gateway — The clearing and settlement engine at gateway.stratumx402.com. Accepts payment submissions, runs netting, executes USDC transfers, and anchors Merkle roots.

Receipt Ledger — An event-sourced ledger (Redis-backed or in-memory) that records every signed receipt within a settlement window. Provides idempotency, position tracking, and window-scoped queries.

Netting Engine — Computes multilateral net positions across all counterparties. Verifies the sum-to-zero invariant and produces a minimal set of USDC transfers.

Merkle Tree — RFC 6962 compliant append-only tree. Every receipt is hashed into a leaf. The root is anchored on Solana for public verifiability.

Settlement Executor — Executes USDC transfers on Solana (SPL Token transferChecked) and Base (ERC-20 transfer) from Stratum's settlement wallet. Creates destination token accounts automatically if they don't exist.

Integration Guide

For Facilitators (Primary Integration)

Facilitators verify x402 payments, then submit them to Stratum for batched settlement.

1. Get an API key at stratumx402.com/facilitators
2. Install the SDK: npm install @v402valeo/facilitator
3. Submit verified payments to Stratum
4. Query settlement status with on-chain txHash proof

const { Stratum } = require('@v402valeo/facilitator');
const stratum = new Stratum({ apiKey: 'sk_live_...' });

// After you verify an x402 payment, submit it to Stratum:
await stratum.submit({
  from: 'agent_wallet_address',
  to: 'service_wallet_address',
  amount: '5000',  // micro-USDC ($0.005)
  chain: 'solana',
  reference: 'your-internal-id'
});

// Check settlement status:
const status = await stratum.status('your-internal-id');
// { status: 'settled', txHash: '4PxAjv...', settledAt: '...' }

For Sellers / API Providers

Sellers register their service and receive USDC automatically. No code changes needed.

1. Get an API key at stratumx402.com/facilitators
2. Register your service with a wallet address
3. USDC arrives every 60 seconds

POST https://gateway.stratumx402.com/admin/services
Content-Type: application/json
X-API-KEY: sk_live_your_key

{
  "slug": "my-api",
  "name": "My API",
  "walletAddress": "your_solana_wallet_address",
  "pricePerRequest": 5000
}

The pricePerRequest is in USDC base units (6 decimals). 5000 = $0.005 USDC per request.

Receipt Format

A receipt is the core clearing primitive. It records that a payer owes a payee a specific amount for a resource within a settlement window.

Receipt Fields

Signed Receipt

A SignedReceipt wraps a receipt with an Ed25519 signature and the signer's public key. The signature is computed over the canonical encoding of the receipt (sorted keys, deterministic BigInt and Uint8Array serialization).

interface SignedReceipt {
  version: number
  receipt: Receipt
  signature: Uint8Array     // Ed25519 signature
  signer_public_key: Uint8Array  // 32-byte public key
}

Merkle Proofs

Stratum uses an RFC 6962 compliant Merkle tree to provide cryptographic proof that every receipt in a settlement window is included in the on-chain commitment.

Hashing Rules

Leaf hash: SHA-256(0x00 || leaf_data)
Node hash: SHA-256(0x01 || left || right)

The 0x00/0x01 prefix prevents second-preimage attacks by making leaf and internal node hashes distinguishable.

Inclusion Proof

An inclusion proof demonstrates that a specific receipt hash is a leaf of the Merkle tree with a known root. The proof contains the sibling hashes along the path from the leaf to the root. Verification recomputes the root by hashing up the path and comparing.

Consistency Proof

A consistency proof demonstrates that a smaller tree (from an earlier point in the window) is a prefix of the larger tree. This proves the tree is append-only: no receipt can be removed or modified after inclusion.

Settlement Windows

A settlement window is a 60-second period during which payments accumulate. When a window closes, netting runs, USDC settles on-chain, and a Merkle root is anchored. A new window opens immediately — zero downtime.

Payments submitted during settlement of the old window go into the new one. No payments are ever dropped.

Window Lifecycle

Netting

Multilateral netting compresses bilateral obligations into a minimal set of net transfers.

Worked Example

Consider 5 agents making API calls to 3 services during a window:

Gross bilateral positions:
  Agent A → Service X: $500
  Agent A → Service Y: $200
  Agent B → Service X: $300
  Agent B → Service Z: $400
  Agent C → Service Y: $150

Net positions after aggregation:
  Agent A:    -$700  (owes $700 net)
  Agent B:    -$700  (owes $700 net)
  Agent C:    -$150  (owes $150 net)
  Service X:  +$800  (owed $800 net)
  Service Y:  +$350  (owed $350 net)
  Service Z:  +$400  (owed $400 net)

Sum of all net positions: $0 ✓ (invariant holds)

USDC transfers executed by Stratum (4 instead of 5):
  → Service X: $800
  → Service Y: $350
  → Service Z: $400

In production, 10,000 bilateral payments compress to ~50 net transfers. The sum-to-zero invariant is always verified before settlement proceeds.

API Reference

The Stratum Gateway at gateway.stratumx402.com exposes these endpoints:

Request Headers

X-API-KEY: sk_live_your_key
Content-Type: application/json

FAQ