[Circle Agent Stack Starter Kit Now Open Source, Supporting Wallets, USDC Payments, and More for AI Agents] Circle announced on the X platform that the Circle Agent Stack Starter Kit is now open source. Developers can add wallet, USDC payment, and on-chain operation functionalities to AI agents within popular frameworks such as OpenAI Agents SDK, Claude Agent SDK, LangChain Deep Agents, Mastra, Vercel AI SDK, and Google AI ADK.