synapse-p2p 2.0.1

A language-agnostic network substrate for agent-to-agent collaboration

A p2p swarm substrate for nodes that find each other, talk to each other, and work together.

from synapse_p2p import Node

node = Node(
    name="reviewer",
    swarm="foo.electron.network",
    capabilities=["code-review"],
    mdns=True,
)

await node.start()
await node.join()

Synapse gives you one primitive: Node.

A node can discover peers, publish capabilities, expose endpoints, receive work, broadcast questions, reply into shared conversations, heartbeat peers, and notice when peers disappear.

Synapse is not an agent framework. It is the clean network layer underneath one.

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Install

pip install synapse-p2p

Then use the CLI:

sn --help

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Why

LLM agents are often isolated. Synapse gives them a small shared substrate:

• discovery — find nodes in the same swarm
• capabilities — know what each node can do
• RPC — call a named endpoint
• ask — delegate a task to a node
• broadcast — ask the whole swarm
• heartbeats — know who is still around
• typed Python API — no dictionary soup
• simple wire protocol — length-prefixed MsgPack over TCP

The goal is not to decide how agents think. The goal is to let them communicate.

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30-second RPC

Create a node:

from synapse_p2p import Node

node = Node(name="calculator", port=9999)


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


node.run()

Call it:

import asyncio

from synapse_p2p import Client


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


asyncio.run(main())

---

Swarms

A swarm is a group of nodes with the same swarm name.

node = Node(
    name="coder",
    role="implementation",
    swarm="foo.electron.network",
    capabilities=["python", "tests"],
)

Use a domain-style name to avoid collisions:

foo.electron.network

Need subgroups? Use optional team. It defaults to "default".

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Local discovery: mDNS

For local machines on the same network:

node = Node(
    name="reviewer",
    swarm="foo.electron.network",
    capabilities=["code-review"],
    mdns=True,
)

await node.start()
await node.join()

Any node on the same LAN with the same swarm and mdns=True can discover it.

Synapse advertises:

_synapse._tcp.local.

mDNS is local by design. It usually does not cross routers, VPN boundaries, or restrictive firewalls.

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Remote discovery: seeds

For private networks or internet-reachable hosts, use seeds:

node = Node(
    name="planner",
    swarm="foo.electron.network",
    seeds=["bootstrap.foo.electron.network:9999"],
)

await node.start()
await node.join()

A seed is just another Synapse node. Once joined, nodes exchange known peers.

By default, nodes listen on 0.0.0.0 and advertise an auto-detected reachable local address. For same-machine-only experiments, use bind="127.0.0.1".

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Capabilities

Simple:

node = Node(capabilities=["python", "code-review"])

Structured:

from synapse_p2p import Capability, Node

node = Node(
    name="researcher",
    capabilities=[
        Capability(
            name="web-research",
            description="Find and summarize sources.",
            input_schema={"query": "string"},
            output_schema={"summary": "string", "sources": "array"},
        )
    ],
)

Inspect a node:

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

---

Ask

Register one ask handler:

node = Node(name="reviewer", capabilities=["code-review"])


@node.ask
async def handle(task: str, context: dict):
    return {"status": "done", "task": task}

Ask another node:

result = await Client.from_peer(peer).call(
    "_node.ask",
    "Review this diff",
    context={"diff": diff},
)

---

Broadcast

Broadcast starts a swarm conversation.

broadcast = await node.broadcast("team.question", "Who can review this diff?")

That returns a Broadcast object:

broadcast.nonce   # conversation id
broadcast.origin  # peer that started it
broadcast.endpoint

The nonce is the conversation atom. Synapse creates UUIDv7 nonces when the Python runtime supports them, so conversations are unique and time-sortable. On older runtimes it falls back to UUIDv4.

Every receiver gets the same Broadcast object. Any node can reply into that conversation by reusing the nonce through node.reply(...):

from synapse_p2p import Broadcast


@node.endpoint("team.question")
async def answer(question: str, broadcast: Broadcast) -> dict:
    await node.reply(broadcast, {"answer": "I can help"})
    return {"accepted": True}

The origin node groups all replies by nonce:

for reply in node.replies(broadcast):
    print(reply.peer.name, reply.result)

Why this matters:

• one broadcast creates one shared event
• the nonce is the conversation id
• every agent sees the same nonce
• any agent can participate by replying with that nonce
• replies group without a central coordinator
• UUIDv7 nonces keep conversation ids roughly ordered by creation time

---

Heartbeats

Nodes heartbeat known peers and mark stale peers offline.

from synapse_p2p import Node, Peer

node = Node(name="planner", heartbeat_interval=5, peer_timeout=20)


@node.on("peer.joined")
async def joined(peer: Peer) -> None:
    print(f"joined: {peer.name}")


@node.on("peer.offline")
async def offline(peer: Peer) -> None:
    print(f"offline: {peer.name}")

Offline means “not seen within peer_timeout.”

---

CLI

Watch a swarm live:

sn watch foo.electron.network

Broadcast and stream replies:

sn broadcast foo.electron.network "Who can review this diff?"

Keep listening:

sn broadcast foo.electron.network "Who can help?" --forever

List local mDNS-visible swarms:

sn list-swarms

sn uses mDNS by default. Use --seed host:port for seed discovery, or --no-mdns to disable local discovery.

---

Typed peer API

Use dataclasses, not dictionaries:

peers = await Client("127.0.0.1", 9000).peers()
reviewer = next(peer for peer in peers if "code-review" in peer.capabilities)
result = await Client.from_peer(reviewer).call("_node.ask", "Review this")

Useful exports:

from synapse_p2p import Broadcast, BroadcastReply, Capability, Client, Node, Peer

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Examples

See examples/.

# two nodes, one delegates to the other
python examples/isolated_agents/agent_alpha.py
python examples/isolated_agents/agent_beta.py
python examples/isolated_agents/ask_alpha.py

# local zero-config mDNS swarm
python examples/local_mdns_swarm/reviewer.py
python examples/local_mdns_swarm/coder.py
python examples/local_mdns_swarm/ask.py

# Pydantic AI team that actually replies over mDNS
python examples/pydantic_ai_team/reviewer.py
python examples/pydantic_ai_team/coder.py
python examples/pydantic_ai_team/product.py
python examples/pydantic_ai_team/ask.py

The Pydantic AI example uses TestModel by default, so it runs without API keys. Set PYDANTIC_AI_MODEL, for example openai:gpt-5.2, to use a real model.

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Built-in endpoints

Substrate endpoints:

Endpoint	Purpose
_synapse.ping	health check
_synapse.info	node identity and swarm metadata
_synapse.methods	published RPC methods
_synapse.peers	known peers
_synapse.join	join through a seed
_synapse.heartbeat	update peer liveness
_synapse.broadcast.reply	reply to a broadcast nonce

Node endpoints:

Endpoint	Purpose
_node.info	name, role, description, capabilities
_node.capabilities	machine-readable capabilities
_node.ask	delegate to the node ask handler

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Wire protocol

Synapse speaks length-prefixed MsgPack over TCP.

Each frame is:

1. 4-byte unsigned big-endian payload length
2. MsgPack payload bytes

Request:

{
    "type": "request",
    "id": "request-id",
    "endpoint": "sum",
    "args": [1, 2],
    "kwargs": {},
}

Response:

{
    "type": "response",
    "id": "request-id",
    "ok": True,
    "result": 3,
    "error": None,
}

Low-level helpers:

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

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Logging

Synapse is quiet by default.

Enable internal logs when debugging:

from loguru import logger

logger.enable("synapse_p2p")

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What Synapse is not

Synapse does not implement planning, memory, consensus, auth policy, NAT traversal, hosted registries, or UX.

Those belong in packages above Synapse.

Synapse is the substrate:

nodes + discovery + capabilities + heartbeats + broadcasts + a tiny protocol

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Roadmap

mDNS and seeds work today. Natural next providers:

• DNS SRV/TXT for domain-backed swarms
• registries and rendezvous servers
• relays for unreachable peers
• NAT traversal
• authenticated swarms

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Keywords

swarm substrate, agent substrate, node discovery, local mDNS discovery, agent-to-agent networking, LLM agent RPC, multi-agent systems, capability discovery, language-agnostic RPC, Python RPC, asyncio RPC, peer-to-peer Python, P2P networking, MsgPack RPC, TCP RPC, distributed agents.