Agent Middleware

Existing AI agent frameworks often lack sufficient control over context engineering, leading developers to create custom code for non-trivial applications. To address this, LangChain 1.0 introduces a new "Middleware" abstraction designed for greater flexibility and composability. This middleware allows developers to inject custom logic before and after model calls, as well as modify the model request itself to better control the agent's behavior. This new approach enables off-the-shelf solutions for complex patterns like human-in-the-loop, conversation summarization, and dynamic model switching.