cyotee/permit2-sdk
.claude/skills/permit2-sdk/SKILL.md
Uniswap Permit2 SDK for gasless token transfers in IndexedEx. Use when implementing swap/deposit/withdraw with signature-based or allowance-based authorization.
development
Updated Apr 16, 2026
$ install --global
skillsauthnpx skillsauth add cyotee/crane permit2-sdkInstall this skill globally with one command. Works with Claude Code, Cursor, and Windsurf.
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Last scanned: Apr 16, 2026, 10:08 PM4.6s1 file scanned
SKILL.md
- name:
- permit2-sdk
- description:
- Uniswap Permit2 SDK for gasless token transfers in IndexedEx. Use when implementing swap/deposit/withdraw with signature-based or allowance-based authorization.
Permit2 SDK for IndexedEx
Comprehensive guide for using Permit2 in the frontend for vault operations.
Quick Start
import { PERMIT2_ADDRESS, SignatureTransfer } from '@uniswap/permit2-sdk'
Two Patterns
1. Signature Transfer (Recommended)
Gasless, no pre-approval needed beyond initial Permit2 allowance.
- Skill:
permit2-signature-transfer - Use for: One-time signatures per swap/deposit/withdraw
- Security: Signature bound to specific action via witness
2. Allowance Transfer
Persistent approvals - user approves once, protocol spends repeatedly.
- Skill:
permit2-allowance-transfer - Use for: Frequent trading, recurring deposits
Exchange Types (Witness Context)
| Exchange | Selector | Witness Data |
|----------|----------|--------------|
| exchangeIn | 0x89d61912 | tokenIn, tokenOut, vault, amountIn |
| exchangeOut | 0x612d4427 | tokenIn, tokenOut, vault, amountOut, maxAmountIn |
| swapSingleTokenExactOut | (Balancer) | pool, tokenIn, tokenOut, amountOut |
Key Topics
- Nonce handling:
permit2-nonce-management - Wagmi integration:
permit2-wagmi-integration - TypeScript types:
permit2-types - Chain addresses:
permit2-addresses
Example: Swap with Witness
// Witness binds signature to this exact swap
const witness = {
actionId: keccak256(encodePacked(
['address', 'address', 'address', 'uint256'],
[tokenIn, tokenOut, vaultAddress, amountIn]
))
}
// Get permit data (EIP-712 ready)
const { domain, types, values } = SignatureTransfer.getPermitData(
permit, // amount, nonce, deadline
PERMIT2_ADDRESS,
chainId,
{ witness, witnessTypeName: 'Witness', witnessType: WITNESS_TYPE }
)
// User signs, then your contract calls Permit2
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