Uniswap Build Hook

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name: build-hook description: >- Build a Uniswap V4 hook. Use when user wants to create a custom V4 hook contract. Generates Solidity code, Foundry tests, mines CREATE2 address for hook flags, and produces deployment scripts. Handles the full hook development lifecycle. allowed-tools: >- Read, Write, Edit, Glob, Grep, Bash(forge:*), Bash(npm:*), Bash(git:*), Task(subagent_type:hook-builder), mcp__uniswap__get_supported_chains model: opus

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Build Hook

Overview

Builds a complete Uniswap V4 hook by delegating to the hook-builder agent. Handles the full development lifecycle: understanding requirements, determining hook flags, generating Solidity contracts, generating Foundry tests, mining a CREATE2 address with correct flag bits, and producing deployment scripts. Returns production-ready code artifacts written directly to the project.

When to Use

Activate when the user asks:

"Build a V4 hook"

"Create a limit order hook"

"Build a dynamic fee hook"

"Create a TWAMM hook"

"Custom hook for V4"

"Hook that charges higher fees during volatility"

"Build a hook that distributes LP fees to stakers"

"Create a hook with oracle integration"

Parameters

| Parameter | Required | Default | Description | | --- | --- | --- | --- | | behavior | Yes | -- | Hook behavior description (e.g., "limit orders", "dynamic fees", "TWAMM", "oracle-based pricing") | | callbacks | No | Auto-detect | Specific V4 callbacks if the user knows them (e.g., "beforeSwap, afterSwap") | | constraints | No | -- | Gas budget, security requirements, or specific design constraints | | chain | No | ethereum | Target chain for deployment (affects PoolManager address) |

Workflow

1. Extract parameters from the user's request: identify the hook behavior, any explicitly mentioned callbacks, constraints, and target chain.

2. Delegate to hook-builder: Invoke Task(subagent_type:hook-builder) with the full context. The hook-builder agent will: - Understand the requirements and determine which callbacks are needed - Map callbacks to hook flags and validate the flag combination - Generate a Solidity contract extending BaseHook with proper NatSpec - Generate comprehensive Foundry tests (unit, integration, edge cases, gas snapshots) - Mine a CREATE2 salt that produces an address encoding the required flags - Produce a deployment script with verification steps

3. Present results to the user with a summary covering: - Files written (contract path, test path, deployment script path) - Hook architecture explanation (what it does, how state flows) - Callbacks implemented and their flag bitmask - Gas estimates per callback (from Foundry test output) - Next steps for the developer (run tests, deploy to testnet, mainnet considerations)

Output Format

Present a summary followed by the generated files:

V4 Hook Built: LimitOrderHook
  Contract:   src/hooks/LimitOrderHook.sol (187 lines)
  Tests:      test/hooks/LimitOrderHook.t.sol (12 tests)
  Deployment: script/DeployLimitOrderHook.s.sol
  Callbacks: beforeSwap, afterSwap
  Flags:     0x00C0
  CREATE2:   Salt mined, address verified
  Gas Estimates:
    beforeSwap: ~45,000 gas
    afterSwap:  ~32,000 gas
    Total overhead per swap: ~77,000 gas
  Architecture:
    Orders are placed at specific ticks and stored in an on-chain order book.
    During beforeSwap, the hook checks for matching orders at the target tick.
    Matched orders are filled atomically within the same transaction.
  Next Steps:
    1. Run tests: forge test --match-contract LimitOrderHookTest
    2. Deploy to testnet: forge script script/DeployLimitOrderHook.s.sol --rpc-url sepolia
    3. Verify on Etherscan: forge verify-contract 
 LimitOrderHook

Important Notes

This skill delegates entirely to the hook-builder agent -- it does not call MCP tools directly.

The hook-builder generates production-quality Solidity code with reentrancy protection and access control.

CREATE2 address mining ensures the deployed address encodes the correct hook flags in its leading bytes (required by V4 PoolManager).

Foundry must be installed for test generation and compilation. If not found, the skill will provide installation instructions.

Generated code uses Solidity ^0.8.26 and imports from @uniswap/v4-core and @uniswap/v4-periphery.

Error Handling

| Error | User-Facing Message | Suggested Action | | --- | --- | --- | | INVALID_CALLBACK_COMBINATION | "The requested behavior requires conflicting callbacks." | Simplify hook behavior or split into multiple hooks | | CREATE2_MINING_TIMEOUT | "Could not mine a valid CREATE2 address within time limit." | Increase mining time limit or reduce required flags | | FORGE_NOT_INSTALLED | "Foundry (forge) is required but not installed." | Install: curl -L https://foundry.paradigm.xyz \| bash && foundryup | | VAGUE_REQUIREMENTS | "Need more detail about the desired hook behavior." | Describe specific behavior (e.g., "limit orders that execute at tick boundaries") | | COMPILATION_ERROR | "Generated contract has compilation errors." | Review error output and adjust requirements |