Alchemy SDK Patterns Overview Production patterns for the package: singleton clients, multi-chain factories, response caching, and type-safe contract wrappers. Instructions Step 1: Multi-Chain Client Factory Step 2: Response Caching Layer Step 3: Typed NFT Query Builder Step 4: Error Classification Output - Multi-chain client factory with lazy initialization - Response cache with configurable TTL - Type-safe NFT query builder pattern - Structured error classification for retry decisions Resources - Alchemy SDK GitHub - Alchemy Docs Next Steps Apply patterns in for real portfolio tracking. ---