c4d27818a1
A model invoked as the root LangChain run (no wrapping chain) — reproduced with Ollama — was emitted by the langfuse v3 CallbackHandler as a separate orphan trace: parent=None, userId=None, sessionId=None, with the token usage detached from the flow trace, breaking cost/usage attribution. Root cause: the SDK only applies the constructor `trace_context` on the chain path (`on_chain_start`); the generation path calls `start_observation` without it, so with no active OpenTelemetry span the generation starts a brand-new trace (metadata `is_langchain_root: true`). `get_langchain_callback` now returns a `CallbackHandler` subclass that, for root LLM runs only (`parent_run_id is None`), activates the flow's component (or root) span as the current OTel span while the SDK creates the generation. The generation then inherits the flow `trace_id` and nests under the component span, restoring user/session attribution and token metrics. Non-root runs (wrapping chain/agent present) are left untouched. Adds focused unit tests plus an end-to-end test that drives the real langfuse SDK with an in-memory OpenTelemetry exporter and asserts the generation shares the flow trace_id and parents under the component span.
Langflow is a powerful platform for building and deploying AI-powered agents and workflows. It provides developers with both a visual authoring experience and built-in API and MCP servers that turn every workflow into a tool that can be integrated into applications built on any framework or stack. Langflow comes with batteries included and supports all major LLMs, vector databases and a growing library of AI tools.
✨ Highlight features
- Visual builder interface to quickly get started and iterate.
- Source code access lets you customize any component using Python.
- Interactive playground to immediately test and refine your flows with step-by-step control.
- Multi-agent orchestration with conversation management and retrieval.
- Deploy as an API or export as JSON for Python apps.
- Deploy as an MCP server and turn your flows into tools for MCP clients.
- Observability with LangSmith, LangFuse and other integrations.
- Enterprise-ready security and scalability.
🖥️ Langflow Desktop
Langflow Desktop is the easiest way to get started with Langflow. All dependencies are included, so you don't need to manage Python environments or install packages manually. Available for Windows and macOS.
⚡️ Quickstart
Install locally (recommended)
Requires Python 3.10–3.14 and uv (recommended package manager).
Install
From a fresh directory, run:
uv pip install langflow -U
The latest Langflow package is installed. For more information, see Install and run the Langflow OSS Python package.
Run
To start Langflow, run:
uv run langflow run
Langflow starts at http://127.0.0.1:7860.
That's it! You're ready to build with Langflow! 🎉
📦 Other install options
Run from source
If you've cloned this repository and want to contribute, run this command from the repository root:
make run_cli
For more information, see DEVELOPMENT.md.
Docker
Start a Langflow container with default settings:
docker run -p 7860:7860 langflowai/langflow:latest
Langflow is available at http://localhost:7860/. For configuration options, see the Docker deployment guide.
🛡️ Security
For security information, see our Security Policy.
🚀 Deployment
Langflow is completely open source and you can deploy it to all major deployment clouds. To learn how to deploy Langflow, see our Langflow deployment guides.
⭐ Stay up-to-date
Star Langflow on GitHub to be instantly notified of new releases.
👋 Contribute
We welcome contributions from developers of all levels. If you'd like to contribute, please check our contributing guidelines and help make Langflow more accessible.