> ## Documentation Index
> Fetch the complete documentation index at: https://langchain-5e9cc07a-preview-apirat-1764626578-896151a.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Changelog

> Log of updates and improvements to LangChain JavaScript/TypeScript

<Update label="Nov 25, 2025">
  ## v1.1.0

  * [Model profiles](/oss/javascript/langchain/models#model-profiles): Chat models now expose supported features and capabilities through a `.profile` getter. These data are derived from [models.dev](https://models.dev), an open source project providing model capability data.
  * [Model retry middleware](/oss/javascript/langchain/middleware/built-in#model-retry): New middleware for automatically retrying failed model calls with configurable exponential backoff, improving agent reliability.
  * [Content moderation middleware](/oss/javascript/langchain/middleware/built-in#content-moderation): OpenAI content moderation middleware for detecting and handling unsafe content in agent interactions. Supports checking user input, model output, and tool results.
  * [Summarization middleware](/oss/javascript/langchain/middleware/built-in#summarization): Updated to support flexible trigger points using model profiles for context-aware summarization.
  * [Structured output](/oss/javascript/langchain/structured-output): `ProviderStrategy` support (native structured output) can now be inferred from model profiles.
  * [`SystemMessage` for `createAgent`](/oss/javascript/langchain/middleware/custom#working-with-system-messages): Support for passing `SystemMessage` instances directly to `createAgent`'s `systemPrompt` parameter and a new `concat` method for extending system messages. Enables advanced features like cache control and structured content blocks.
  * [Dynamic system prompt middleware](/oss/javascript/langchain/agents#dynamic-system-prompt): Return values from `dynamicSystemPromptMiddleware` are now purely additive. When returning a [`SystemMessage`](https://reference.langchain.com/javascript/classes/_langchain_core.messages.SystemMessage.html) or `string`, they are merged with existing system messages rather than replacing them, making it easier to compose multiple middleware that modify the prompt.
  * **Compatibility improvements:** Fixed error handling for Zod v4 validation errors in structured output and tool schemas, ensuring detailed error messages are properly displayed.
</Update>

<Update label="Oct 20, 2025">
  ## v1.0.0

  * [Release notes](/oss/javascript/releases/langchain-v1) - Detailed release notes
  * [Migration guide](/oss/javascript/migrate/langchain-v1) - How to migrate to LangChain v1
</Update>

## Resources

* [Release policy](/oss/javascript/release-policy) – Detailed release policies
* [Versioning](/oss/javascript/versioning) – Understanding version numbers
* [Report issues on GitHub](https://github.com/langchain-ai/langchainjs/issues)

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