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Build x402 payment flows using MetaMask Smart Accounts Kit, machine to machine payments over HTTP with ERC-7710 delegations and ERC-7715 Advanced Permissions
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SOC 職業分類に基づく
E2E testing guidelines
Add a new EVM network to the @metamask/bridge-controller package in the MetaMask/core monorepo. Use when a task asks to register an EVM chain for Swaps or Bridge, extend ALLOWED_BRIDGE_CHAIN_IDS or DEFAULT_CHAIN_RANKING, add bridge chain constants and display names, define the chain's default swaps token, or expose a new bridge ChainId enum member.
Add a new EVM network to the unified Swaps and Bridge flow in MetaMask/metamask-mobile. Use when a task asks to consume a newly supported bridge-controller chain, add a Mobile bridge network label, configure its default destination token or stablecoin slippage, update bridgeConfigV2 rollout requirements, or validate that a new EVM network appears in Mobile's source and destination network pickers.
Wire a new or existing controller — whether imported from a `@metamask/*-controller` npm package or defined locally in the repo — into the MetaMask Mobile Engine or the MetaMask Extension background. Use this skill when: adding a controller to Engine or to the extension's messenger-client init, creating a controller init function or messenger, delegating actions/events between controllers, adding a controller to EngineState/Engine.context or to MESSENGER_FACTORIES and the MessengerClient union, or debugging a controller whose state never reaches Redux/the UI or resets on restart.
Detect, prevent, and fix flaky Jest unit tests in MetaMask Mobile before they reach CI. Use this skill when: reviewing a PR diff or changed test files for flakiness risk, fixing an intermittently failing Jest test, reproducing a flaky test locally, or auditing GitHub Actions history to rank historically flaky unit tests by failure rate.
Interactively break a perps product requirement into split, dispatch-ready technical tickets across MetaMask Core, its release, Mobile, and Extension. Use when a product manager (or a codebase-aware Claude acting for one) has a perps bug or feature and needs engineering-grade tickets, correctly routed now that @metamask/perps-controller is the Core source of truth. Triages where the change actually lives, emits only the applicable layer tickets with dependency links, and enforces token-efficient, signal-over-noise tickets agents can act on directly.
| name | x402-payments |
| description | Build x402 payment flows using MetaMask Smart Accounts Kit, machine to machine payments over HTTP with ERC-7710 delegations and ERC-7715 Advanced Permissions |
x402 is an open payment protocol that uses the HTTP 402 status code to enable programmatic, machine-to-machine payments over HTTP. It lets servers charge for API access without requiring traditional payment infrastructure, buyer accounts, or API keys.
npm install @x402/core @x402/fetch @metamask/x402 @metamask/smart-accounts-kit
For seller endpoints:
npm install @x402/core @x402/express @metamask/x402
PAYMENT-REQUIRED header containing payment terms.PAYMENT-SIGNATURE header.The standard x402 protocol supports direct token transfers (using ERC-20 Permit2 or EIP-3009). ERC-7710 extends this by enabling delegation-based payments from MetaMask smart accounts.
With ERC-7710, a buyer's smart account creates a delegation that authorizes the facilitator to transfer tokens on their behalf. The buyer doesn't sign a direct token approval. Instead, they sign a delegation that the facilitator redeems during settlement.
This approach enables buyers to pay from MetaMask wallet. Buyers can restrict delegations to specific facilitator addresses, amounts, and time windows using delegation scopes. They can also create long-lived delegations that allow recurring payments without re-signing for each request.
| Workflow | Use case |
|---|---|
| Seller endpoint setup | You want to protect API endpoints with x402 payment requirements. |
| Delegation payments | You control the buyer smart account and want to automate payments programmatically. |
| Advanced Permissions (recurring) | You want to request a periodic budget from a MetaMask user for ongoing API access. Best for subscriptions and recurring usage. |
If the user hasn't specified which payment method they need, present the options.
| Network | Chain ID | Facilitator URL |
|---|---|---|
| Base | eip155:8453 | https://tx-sentinel-base-mainnet.dev-api.cx.metamask.io/platform/v2/x402 |
| Base Sepolia | eip155:84532 | https://tx-sentinel-base-sepolia.dev-api.cx.metamask.io/platform/v2/x402 |
| Monad | eip155:143 | https://tx-sentinel-monad-mainnet.dev-api.cx.metamask.io/platform/v2/x402 |