build-hook

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

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 <address> 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