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use-modular-wallets

Build smart contract wallets with passkey authentication and gasless transactions using Circle Modular Wallets SDK.

1|Updated Sep 4, 2025
Search Tags:#passkey#web3#circle#erc-4337#account abstraction#gasless transactions#modular wallets
One-click install
npx skills add https://github.com/FuzzysTodd/The-Nexus-Protocol-Token-DAO --skill use-modular-wallets-fuzzystodd
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: use-modular-wallets
Source: https://github.com/FuzzysTodd/The-Nexus-Protocol-Token-DAO/tree/main/skills/use-modular-wallets
Command: npx skills add https://github.com/FuzzysTodd/The-Nexus-Protocol-Token-DAO --skill use-modular-wallets-fuzzystodd

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires @circle-fin/modular-wallets-core, viem, bip39, and includes references (resource) components.

What problem does it solve? Building crypto wallets traditionally requires managing private keys, paying gas fees, and handling complex account abstraction logic. This Skill guides you through creating modular smart contract accounts (MSCAs) with passkey-based login, sponsored gas, and extensible onchain modules using the Circle Modular Wallets SDK. ## Core Features & Use Cases - Passkey Authentication: Register and log in users with WebAuthn passkeys instead of seed phrases, with BIP-39 mnemonic recovery as a fallback. - Gasless & Batched Transactions: Sponsor gas via Circle Gas Station paymaster and batch multiple calls into a single user operation. - Modular Extensions: Add custom modules like multisig, subscriptions, and session keys to MSCAs built on ERC-4337 and ERC-6900. - Use Case: Build a consumer dApp on Polygon where users sign up with a fingerprint, send USDC without holding native tokens for gas, and recover their wallet with a mnemonic if they lose their device. ## Quick Start Ask the AI to create a Circle modular smart account with passkey registration and send a gasless USDC transfer on Polygon Amoy testnet.

Frequently Asked Questions about use-modular-wallets

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I create a crypto wallet with passkey authentication?▼

Use the Circle Modular Wallets SDK with toPasskeyTransport to register a WebAuthn credential, then create a smart account via toCircleSmartAccount. Passkeys are domain-bound, so configure your Passkey Domain in the Circle Console first.

How to send gasless transactions with ERC-4337 account abstraction?▼

Pass paymaster: true in your sendUserOperation call to sponsor gas through Circle Gas Station. On mainnet, you must configure a Gas Station paymaster policy in the Circle Console before creating accounts.

Which blockchains support Circle Modular Wallets MSCAs?▼

MSCAs are supported on Arbitrum, Avalanche, Base, Monad, Optimism, Polygon, and Unichain mainnets, plus Arc testnet. They are not available on Ethereum mainnet, Solana, Aptos, or NEAR.

How do I recover a passkey wallet if the device is lost?▼

Set up BIP-39 mnemonic recovery using the bip39 package as described in the passkey recovery reference. Store the recovery phrase outside your repository and never reuse it across multiple accounts.

Why does my user operation fail with error AA21 or 155203?▼

AA21 means the sender did not pay prefund, so enable paymaster: true or fund the account with native tokens. Error 155203 means the wallet is not deployed yet, so send the first user operation with nonce 0 since MSCAs deploy lazily.

When should I use modular wallets instead of user-controlled wallets?▼

Use modular wallets when you need passkey authentication, gas sponsorship, batching, or custom modules like multisig and session keys. Choose user-controlled wallets when end users should custody keys via social login, email OTP, or PIN.

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