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https://github.com/langchain-ai/langgraph.git
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Mason DaughertyandGitHub
8558481859
Aligns the repository's package READMEs around a shared documentation shape so users see consistent install, positioning, docs, release, and contribution guidance across LangGraph packages.
97 lines
4.4 KiB
Markdown
97 lines
4.4 KiB
Markdown
# LangGraph Python SDK
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[](https://pypi.org/project/langgraph-sdk/#history)
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[](https://opensource.org/licenses/MIT)
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[](https://pypistats.org/packages/langgraph-sdk)
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[](https://x.com/langchain_oss)
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To help you ship LangGraph apps to production faster, check out [LangSmith](https://www.langchain.com/langsmith).
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[LangSmith](https://www.langchain.com/langsmith) is a unified developer platform for building, testing, and monitoring LLM applications.
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## Quick Install
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```bash
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uv add langgraph-sdk
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```
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## 🤔 What is this?
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This library provides the Python SDK for interacting with the LangGraph API. Use it to connect to a running LangGraph API server, manage assistants and threads, and stream runs from Python applications.
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You will need a running LangGraph API server. If you're running a server locally using `langgraph-cli`, the SDK will automatically point at `http://localhost:8123`; otherwise, specify the server URL when creating a client.
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## 📖 Documentation
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For full documentation, see the [API reference](https://reference.langchain.com/python/langgraph-sdk/). For conceptual guides and tutorials, see the [LangGraph Docs](https://docs.langchain.com/oss/python/langgraph/overview).
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## Quick Start
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```python
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from langgraph_sdk import get_client
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# If you're using a remote server, initialize the client with `get_client(url=REMOTE_URL)`
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client = get_client()
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# List all assistants
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assistants = await client.assistants.search()
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# We auto-create an assistant for each graph you register in config.
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agent = assistants[0]
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# Start a new thread
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thread = await client.threads.create()
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# Start a streaming run
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input = {"messages": [{"role": "human", "content": "what's the weather in la"}]}
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async for chunk in client.runs.stream(thread['thread_id'], agent['assistant_id'], input=input):
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print(chunk)
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```
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## Known Limitations
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- **WebSocket transport** requires `websockets>=14` and is only available on the async client (`AsyncThreadStream`). The sync client (`SyncThreadStream`) uses SSE exclusively.
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- **`thread.extensions[name]`** opens a new subscription each time the same name is accessed. Assign the projection to a variable and reuse it within a single session rather than re-indexing across multiple iterations.
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- **Sync streaming** drives the lifecycle watcher in a background thread. Long-lived sync sessions will hold that thread open until the context manager exits.
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- **Reconnect attempts** are limited to 5 by default for both the shared SSE fan-out and the lifecycle watcher. Persistent network partitions will surface as `RuntimeError` on in-flight projections.
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## Thread-Centric Streaming (v3)
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`client.threads.stream()` returns a context manager that owns the SSE session for one thread. Typed projections — values snapshots, message streams, tool calls, custom events — all share the same underlying connection.
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```python
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from langgraph_sdk import get_client
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import asyncio
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client = get_client()
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async with client.threads.stream(
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thread_id="my-thread",
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assistant_id="agent",
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) as thread:
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await thread.run.start(input={"messages": [{"role": "user", "content": "hi"}]})
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# Start all consumers concurrently so they share one SSE connection.
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async def get_messages():
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return [s async for s in thread.messages]
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async def get_tool_calls():
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return [c async for c in thread.tool_calls]
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messages, tool_calls = await asyncio.gather(get_messages(), get_tool_calls())
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for stream in messages:
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print(await stream.text) # accumulated text
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final = await thread.output # terminal state values
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```
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## 📕 Releases & Versioning
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See our [Releases](https://docs.langchain.com/oss/python/release-policy) and [Versioning](https://docs.langchain.com/oss/python/versioning) policies.
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## 💁 Contributing
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As an open-source project in a rapidly developing field, we are extremely open to contributions, whether it be in the form of a new feature, improved infrastructure, or better documentation.
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For detailed information on how to contribute, see the [Contributing Guide](https://docs.langchain.com/oss/python/contributing/overview).
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