Sekisho MCP

Sekisho 関所 · Kanjō 勘定

AI agents that sell — and get paid. x402 payments on Avalanche with an on-chain revenue split, run in batches by a built-in distributor.

• Sekisho (関所, checkpoint): on-chain payment layer + SDK. Any API or MCP tool can charge USDC via x402; every payment lands in the seller's SplitVault, which splits the platform fee and the seller's share.
• Kanjō (勘定, the bill): an AI sales agent for small businesses. It chats with customers, builds orders and collects payment through Sekisho.

Status: live on Avalanche C-Chain mainnet (Sekisho contracts and SDK). Kanjō runs on Fuji testnet. See SECURITY.md. Website: https://sekisho.zerotwolabs.xyz · SDK: @zero-two-labs/sekisho

Repository

How a payment flows

Customer ──chat──▶ Kanjō agent (Claude) ──▶ order + payment link
   │
   └─ signs EIP-3009 authorization (gasless) ──▶ Kanjō facilitator settles USDC
                                                     │
                                                     ▼
                                     Merchant's SplitVault (deterministic address)
                                                     │  distribute() — batched
                                     ┌───────────────┴───────────────┐
                                     ▼                               ▼
                             Treasury (1.5%)                  Merchant (98.5%)

Deployments

Avalanche C-Chain mainnet (eip155:43114)

First x402 payment on mainnet (2026-10-28), through the demo API: an agent paid 0.01 USDC for GET /v1/avalanche/snapshot, the server settled it into the seller's vault, and the SDK's distributor split it automatically, 19 seconds later. For this test the demo's split threshold was lowered to 0.01 USDC; in normal operation it batches splits (1 USDC, or 24 h once 0.25 USDC is pending), so later payments wait in the vault until then.

Avalanche Fuji testnet (eip155:43113)

Deprecated factories on Fuji: v2 0x198F21AF47221bb06dAAf8e4F5eB46F9ba388807 (no fee delay, SDK 0.2.x) and v1 0xA1967201adD1Ac57d1c72D04Ca4d9159B98C8C5D (no merchant rotation, SDK ≤ 0.1.5).

Security model

• Fee hard cap and 7-day delay: MAX_FEE_BPS = 1000 (10%) is enforced in the contract; not even the owner can exceed it. Every fee change is scheduled and applies 7 days later (FEE_CHANGE_DELAY). The fee is applied when funds are split, not when they are charged: calling distribute() before the deadline splits pending funds at the old rate, and the SDK's distributor does it automatically when it sees a scheduled increase. Current fee: 1.5%.
• Permissionless, fixed-destination splits: anyone can call distribute(), but funds can only go to the treasury and the merchant.
• No withdraw function: everything that enters a vault can only leave through distribute(). Vaults reject native AVAX.
• Two-step merchant rotation: only the current merchant can propose a new payout address and only that address can accept; anything pending is paid to the previous address first.
• Separated keys: on mainnet, owner and treasury are a Safe 2-of-3 multisig; on Fuji they are two separate single-key wallets. The server's operator key settles payments and triggers splits but holds no permissions on the contracts.
• No lost payments: a settled payment is always recorded, even if stock ran out (the order is flagged for refund). A per-order lock prevents double settlement; WhatsApp webhooks are deduplicated by message id.

Quickstart

Contracts

cd backend && npm install && npx hardhat test

Start charging in 5 minutes

npm create @zero-two-labs/sekisho my-api -- --merchant 0xYourWallet

A ready-to-run paid API: x402 endpoint, your SplitVault, automatic distributor and a fresh operator key in .env. See packages/create-sekisho.

SDK

npm install @zero-two-labs/sekisho viem

See sdk/README.md for seller, agent, facilitator, MCP and distributor (keeper) examples.

Kanjō (no WhatsApp account needed for local testing)

cd apps/kanjo
cp .env.example .env      # fill MERCHANT_ADDRESS, ANTHROPIC_API_KEY, OPERATOR_PRIVATE_KEY
npm install
npm run seed              # demo store and catalog
npm run chat              # talk to the agent in your terminal
npm run dev               # server + checkout at http://localhost:3000

Checks: npm run test:safety · npm run test:distribution · npm run test:webhook · npm run gas:report

Economics (measured October 2026)

With mainnet gas at 2.5 nAVAX and AVAX ≈ $9.5:

With a 1.5% fee, the minimum viable ticket is ~$0.30 splitting every order and ~$0.17 splitting in batches. That is why the SDK's distributor and Kanjō split in batches (≥ 5 USDC, or every 24 h once at least 0.25 USDC is pending). Run npm run gas:report in apps/kanjo for live numbers.

Roadmap

• Mobile checkout from WhatsApp's in-app browser (WalletConnect or embedded wallets)
• Fiat on-ramp (SPEI → USDC into the same vault) through a regulated provider
• batch-settlement x402 scheme for sub-cent MCP micropayments

License

MIT © Zero Two Labs

Built at Hacktoberfest México 2026

Built on October 28, 2026, during the Hacktoberfest México Build Day, on top of the existing repo:

• Catalog from any URL with Firecrawl (apps/kanjo/src/catalog-import.ts): npm run catalog:import -- <url> extracts products, prices, sections and photos into a preview with a diff; npm run catalog:apply -- <id> writes them. Prices in MXN are converted to USDC. Demo menu: /demo/menu.html.
• Voice with ElevenLabs (apps/kanjo/src/voice.ts): customers talk to the agent from the browser (/voice) and it answers out loud; payment links always stay on screen as text. WhatsApp voice notes in and out are wired too (VOICE_REPLIES=on).

Everything before these commits already existed: v3 contracts on Avalanche mainnet, the @zero-two-labs/sekisho SDK and the x402 checkout with on-chain revenue split. The Kanjō demo runs on Avalanche Fuji testnet.