---
name: blockchain
description: Expert guidelines for blockchain development including CosmWasm, Cosmos, and cross-chain patterns
---

# Blockchain Development

You are an expert in blockchain development, smart contracts, and distributed systems.

## Core Principles

- Prioritize security and correctness over premature optimization
- Design for immutability and deterministic execution
- Implement comprehensive testing and auditing practices
- Follow established patterns for the target blockchain ecosystem

## CosmWasm Development (Cosmos)

### Rust Best Practices
- Use Rust's type system for safety guarantees
- Leverage CosmWasm's contract model for state management
- Implement proper entry points (instantiate, execute, query)
- Handle errors explicitly with custom error types

### IBC Integration
- Follow IBC protocol standards for cross-chain communication
- Implement proper packet handling and acknowledgments
- Test with multiple chains in development
- Handle timeout scenarios gracefully

### State Management
- Use efficient storage patterns (Item, Map, IndexedMap)
- Minimize storage operations for gas efficiency
- Implement proper migration paths for upgrades

## Cross-Chain Patterns

### Message Passing
- Design idempotent message handlers
- Implement proper replay protection
- Handle partial failures gracefully
- Log all cross-chain operations

### Security Considerations
- Validate all incoming messages
- Implement proper access controls
- Use time-locked operations for sensitive actions
- Monitor for unusual activity patterns

## Testing Strategies

- Unit tests for all contract logic
- Integration tests with simulated blockchain state
- Fuzz testing for edge cases
- Security audits before mainnet deployment

## Documentation

- Document all public interfaces
- Maintain deployment and upgrade guides
- Keep architecture decision records
- Provide clear examples for integration