A network substrate for Python agents.

Synapse P2P is a tiny async RPC, discovery, and capability-publishing layer for building agent-to-agent networks, local agent swarms, distributed tools, peer-to-peer services, and lightweight service meshes.

It is designed to be useful to both humans and LLM agents:

• Humans get a simple Python API.
• Agents get discoverable methods, published capabilities, structured request/response messages, and machine-readable metadata.

@app.endpoint("sum")
async def sum_endpoint(a: int, b: int) -> int:
    return a + b

result = await Client("127.0.0.1", 9999).call("sum", 1, 2)

LLM agents need a way to find each other, ask what each other can do, and delegate work over a small, predictable protocol.

Synapse provides the substrate for that:

• RPC: call remote Python functions over TCP.
• Discovery: inspect published methods and agent capabilities.
• Agent identity: expose role, description, and capabilities.
• Delegation: send tasks to another agent through _agent.ask.
• Structured protocol: MsgPack request/response envelopes with request IDs and errors.

Think of it as a minimal network layer for agentic systems — not a framework that decides how agents think, but a substrate they can use to connect.

• Async TCP RPC built on asyncio
• MsgPack serialization for compact binary messages
• Length-prefixed framing for reliable message boundaries over TCP
• Decorator-based endpoints with @app.endpoint(...)
• Built-in async client with request/response handling
• Structured responses and errors via RPCResponse and RPCError
• Positional and keyword arguments for remote calls
• Request IDs for correlation and future persistent-connection support
• Published method discovery via _synapse.methods
• Agent metadata discovery via _agent.info and _agent.capabilities
• Agent task delegation via _agent.ask
• Periodic background tasks with @app.background(...)
• Serializer abstraction for custom protocols later
• P2P-oriented primitives such as node identity and XOR-distance helpers

pip install synapse-p2p

For development with uv:

uv sync --group dev
uv run pytest
uv run ruff check .
uv run pyrefly check

Create a server:

from synapse_p2p import Server

app = Server(address="127.0.0.1", port=9999)  # or Server() for defaults


@app.endpoint("sum", description="Add two numbers")
async def sum_endpoint(a: int, b: int) -> int:
    """Add two numbers."""
    return a + b


if __name__ == "__main__":
    app.run()

Call it from a client:

import asyncio

from synapse_p2p import Client


async def main() -> None:
    client = Client("127.0.0.1", 9999)
    result = await client.call("sum", 1, 2)
    print(result)


asyncio.run(main())

Output:

3

An AgentNode is a Synapse server that publishes agent metadata and accepts delegated work.

from synapse_p2p import AgentNode

agent = AgentNode(
    name="Reviewer",
    role="reviewer",
    description="Reviews Python code and suggests tests.",
    capabilities=["python", "code-review", "pytest"],
)


@agent.task_handler
async def handle_task(task: str, context: dict):
    return {
        "status": "done",
        "result": f"Reviewed task: {task}",
        "context_keys": list(context),
    }


agent.run()

Another agent or client can inspect it:

info = await client.call("_agent.info")
capabilities = await client.call("_agent.capabilities")

And delegate work:

result = await client.call(
    "_agent.ask",
    "Review this pull request",
    context={"files": ["server.py", "client.py"]},
)

Synapse reserves _synapse.* for substrate-level metadata.

Health check:

await client.call("_synapse.ping")
# "pong"

Returns published RPC methods:

methods = await client.call("_synapse.methods")
print(methods)

For this endpoint:

@app.endpoint("sum")
async def sum_endpoint(a: int, b: int) -> int:
    """Add two numbers."""
    return a + b

The result is:

[
    {
        "name": "sum",
        "publish": True,
        "description": "Add two numbers.",
    }
]

Endpoints are published by default. Add a docstring to make them more useful to humans and agents inspecting _synapse.methods:

@app.endpoint("image.resize")
async def resize_image(...):
    """Resize an image."""
    ...

Private endpoints can opt out:

@app.endpoint("admin.restart", publish=False)
async def restart():
    ...

Synapse reserves _agent.* for agent-level metadata and task delegation.

Returns agent identity:

{
    "name": "Reviewer",
    "role": "reviewer",
    "description": "Reviews Python code and suggests tests.",
    "capabilities": ["python", "code-review", "pytest"],
}

Returns machine-readable capability descriptors:

[
    {
        "name": "code-review",
        "description": "Review Python code for correctness and maintainability.",
        "input_schema": {},
        "output_schema": {},
    }
]

Capabilities can be strings or explicit descriptors:

from synapse_p2p import AgentCapability, AgentNode

agent = AgentNode(
    name="Researcher",
    role="researcher",
    capabilities=[
        AgentCapability(
            name="web-research",
            description="Find and summarize evidence from the web.",
            input_schema={"query": "string"},
            output_schema={"summary": "string", "sources": "array"},
        )
    ],
)

Delegates a task to the agent's registered task handler:

await client.call(
    "_agent.ask",
    "Find bugs in this module",
    context={"code": "..."},
)

The task handler receives:

async def handle_task(task: str, context: dict):
    ...

info = await client.call("_agent.info")
methods = await client.call("_synapse.methods")
capabilities = await client.call("_agent.capabilities")

if "code-review" in info["capabilities"]:
    result = await client.call("_agent.ask", "Review this diff", context={"diff": diff})

@app.endpoint("filesystem.search")
async def search_files(pattern: str) -> list[str]:
    """Search files by regex."""
    ...

@app.endpoint("shell.exec", publish=False)
async def shell_exec(command: str) -> str:
    ...

Private methods are still callable if known, but they are not advertised by _synapse.methods.

Use app.run() for simple scripts. In larger async applications or tests, use start() and stop():

server = await app.start()
try:
    ...
finally:
    await app.stop()

Synapse can run recurring async background jobs alongside your RPC server:

from synapse_p2p import Server

app = Server()


@app.background(5)
async def heartbeat():
    print("heartbeat: server is still alive")


@app.endpoint("sum")
async def sum_endpoint(a: int, b: int) -> int:
    return a + b


if __name__ == "__main__":
    app.run()

Startup output will include the task:

Background Tasks:
- heartbeat (5s)

The task above runs roughly every five seconds. Exceptions are logged and do not stop future runs.

Synapse sends length-prefixed MsgPack messages over TCP.

A request looks like:

RPCRequest(
    id="request-id",
    endpoint="sum",
    args=[1, 2],
    kwargs={},
)

A successful response looks like:

RPCResponse(
    id="request-id",
    ok=True,
    result=3,
)

An error response looks like:

RPCResponse(
    id="request-id",
    ok=False,
    error=RPCError(code="bad_request", message="Unregistered endpoint called: nope"),
)

Most users should use Client, but lower-level message types are exported if you want to build custom transports or tooling:

from synapse_p2p import RPCError, RPCRequest, RPCResponse, RemoteProcedureCall
from synapse_p2p.framing import read_frame, write_frame
from synapse_p2p.serializers import MessagePackRPCSerializer

RemoteProcedureCall is kept as a backwards-compatible alias for RPCRequest.

Synapse is intentionally small and evolving. The current focus is a clean async RPC and agent substrate. Future work may include:

• Peer discovery and bootstrap peer exchange
• Agent-to-agent network discovery
• Long-running jobs for agent tasks
• Persistent connections and streaming events
• Routing tables / Kademlia-style node lookup
• Handshakes and node capabilities
• Authenticated or encrypted messages
• Broadcast and gossip primitives

Python agent substrate, agent-to-agent networking, LLM agent RPC, multi-agent systems, agent discovery, capability discovery, Python RPC, asyncio RPC, peer-to-peer Python, P2P networking, MsgPack RPC, TCP RPC, async microservices, distributed agents, distributed workers, service-to-service communication.