Overview

MOSS is MegaETH's embedded wallet SDK — connect, sign, transact, and delegate through a hosted iframe model.

MOSS embeds a wallet UI in a hosted iframe (https://account.megaeth.com) and exposes wallet actions to your app over a Penpal message bridge. Your app controls when to initialise, when to prompt the user, and how wallet state drives product UX. Private keys never touch your app code.

Two integration paths share one runtime:

• Core SDK (@megaeth-labs/wallet-sdk) — framework-agnostic, minimal dependency surface. Use for vanilla TS, Vue, Svelte, custom shells.
• React SDK (@megaeth-labs/wallet-sdk-react) — provider + hooks built on TanStack Query semantics. Use for React 19 products.

For React apps already on wagmi, the Wagmi Connector drops MOSS in as a wagmi connector instead.

Architecture

1. App calls mega.initialise(config).
2. SDK creates a hidden iframe pointed at the wallet host (production: https://account.megaeth.com; dev: local host).
3. Penpal establishes a parent/iframe bridge scoped to the expected origin.
4. Wallet iframe signals ready after status check.
5. App calls connect, signMessage, transfer, callContract, etc.

Network enum is currently 'mainnet' | 'testnet'. Sponsorship config (sponsorUrl, mode, fee token) passes during initialisation — see Paymaster Guide.

What MOSS is — and is Not

Model	MOSS today
Embedded wallet SDK	Yes — the primary integration model.
Injected browser wallet	No — MOSS is SDK-first, not extension-first.
WalletConnect wallet	Planned (roadmap).
Session-key smart accounts	Yes — Smart Approvals (Policy Engine) powers app permissions and delegated execution.

Where to Go Next

• New to MOSS: Quickstart — install, initialise, first transaction.
• Backend integration: Server Verify for SIWE validation, MOSS Authentication for JWT-based auth without direct SIWE prompts.
• Funding UX: Deposit Flows (Unifold) — built-in deposit flow is the recommended path.
• Permissions: Smart Approvals — session grants and delegated execution.
• Sponsorship: Paymaster Setup — sponsor URL, mode, fee token.
• Reference: Methods Reference for the full method/type contract; Examples for runnable code.
• Going to production: Integration Checklist then Best Practices.
• AI agents: Agent Skills Pack for sharable agent skills; AI Agent Guide for policy patterns.

Published packages: wallet-sdk on npm · wallet-sdk-react on npm.

Roadmap

These are direction signals, not shipped behavior:

Area	Planned
Social login onboarding	Google, Apple, email-based flows aligned to MOSS auth UX.
WalletConnect v2	Session management for WalletConnect-compatible dapps.
EIP-6963 / EIP-1193 discovery	Compatibility layer for broader wallet discoverability.