langchain-synapse

Dead-simple LangChain integration for the Synapse decentralized inference network. Wraps the orchestrator's POST /api/infer endpoint as a standard LangChain LLM so Synapse plugs into any chain, agent, or RAG pipeline.

Install

From PyPI:

pip install synapse-langchain

From source:

cd integrations/langchain-synapse
pip install -e .

Distribution name on PyPI is synapse-langchain; the Python import name is langchain_synapse (unchanged).

Use

from langchain_synapse import SynapseLLM

llm = SynapseLLM(
    token_id="1",                                          # model NFT id
    user="0x0000000000000000000000000000000000000001",     # your wallet
    base_url="http://localhost:8000",                      # orchestrator
    max_tokens=128,
)

print(llm.invoke("Hello from LangChain!"))

Works with LCEL out of the box:

from langchain_core.prompts import ChatPromptTemplate
from langchain_core.output_parsers import StrOutputParser

chain = ChatPromptTemplate.from_template("Q: {q}\nA:") | llm | StrOutputParser()
chain.invoke({"q": "What is decentralized inference?"})

Demos

# Make sure the orchestrator is running:
#   ROLE=orchestrator uvicorn backend.main:app --port 8000

python examples/demo.py
python examples/chain_demo.py

Config

session_id must come from Marketplace.openSession for real paid runs. Leave it None only when demoing against a dev orchestrator.

How it works

SynapseLLM._call just POSTs to /api/infer with the Synapse InferenceRequest shape and returns outputStr from the response. That's the entire integration — 60-ish lines.