AI Chat Assistant Integration Specialist Needed

We need a developer to integrate a custom AI chat assistant into an existing MERN stack application. This is a small one time project. The frontend chat interface is already there, and the backend infrastructure is already there. We need someone to hook up the existing app to an AI provider and finish the integration. Requirements React, Node.js experience Experience with integrating AI APIs like OpenAI, Claude or Gemini. Familiarity with REST API and database operations Experience working within an existing code structure and repository Notes The chat UI is already built No vector database or RAG implementation is required No advanced AI workflows or agent systems are required This is a straightforward AI integration project Please include examples of previous AI integrations or chatbot projects when applying.