LangChain Changelog

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February 2026

Pin a baseline experiment in LangSmith

You can now pin any experiment as your baseline, so every subsequent run is automatically measured against it. Instead of manually selecting experiments for...

February 19, 2026

Agent Builder: chat, file uploads, and tool registry

We built Agent Builder around a simple idea: working with an agent should feel like working with a teammate. There's now a central Chat agent with access to...

February 18, 2026

Scheduled reports for Insights Agent

The LangSmith Insights Agent now runs on your schedule, no manual triggers required. Set a recurring cadence (daily, weekly, or a custom cron expression) and...

February 17, 2026

Deep Agents v0.4

deepagents v0.4 ships pluggable sandbox support, smarter conversation history summarization, and Responses API as the default for OpenAI models. Agents can...

February 10, 2026

Customize trace previews in LangSmith

You can now configure which parts of a trace’s inputs and outputs appear directly in the tracing table. This is especially useful for projects with custom...

February 6, 2026

Track costs across your entire agent stack

LangSmith now gives you a unified view of costs across your full agent workflow, not just LLM calls. Submit custom cost metadata for any run, whether that's...

February 5, 2026

January 2026

LangSmith Self-Hosted

LangSmith Self-Hosted v0.13

This self-hosted release expands feature parity with LangSmith Cloud while improving performance, security, and operational control. It brings Insights , the...

January 16, 2026

December 2025

Pairwise annotation queues for comparing agent outputs

Pairwise Annotation Queues in LangSmith are a fast, structured way to compare two agent outputs side-by-side and pick a winner. Scoring subjective tasks is...

December 17, 2025

LangSmith Fetch: Debug agents from your terminal

We've launched LangSmith Fetch — a CLI tool that brings full LangSmith trace access directly into your terminal, coding environment, or IDE. If you build...

December 10, 2025

LangSmith Polly, our AI assistant for debugging, analyzing, and improving agents, is now in beta

We've launched Polly — an AI-powered assistant inside LangSmith that helps you debug, analyze, and improve your agents. Polly, now in beta, understands agent...

December 10, 2025

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