The Stacks network has activated Clarity 4, a significant upgrade to its smart contract language, following the approval of SIP-033 and SIP-034 at Bitcoin block height 923222. This update introduces six new features designed to enhance Bitcoin-native DeFi development. Key additions include on-chain contract code hash retrieval, custom contract post-conditions, and secp256r1 signature verification, among others. These enhancements aim to simplify the development of secure and flexible financial protocols on Bitcoin, positioning Stacks as a crucial liquidity layer within the Bitcoin ecosystem. All transactions on Stacks are settled on the Bitcoin chain, leveraging the proof-of-transfer mechanism for security.