Adapters and Concurrency

Adapters

Adapters bridge external protocols (MCP, NoneBot, etc.) to internal plugin calls. They implement a gateway pipeline pattern.

When to use Adapters

• You want to expose N.E.K.O plugins via MCP (Model Context Protocol)
• You want to accept NoneBot messages and route them to plugins
• You want to bridge any external protocol to the plugin system

Adapter Gateway Pipeline

External Request → Normalizer → PolicyEngine → RouteEngine → PluginInvoker → ResponseSerializer → External Response

Stage	Responsibility
Normalizer	Convert external protocol format to GatewayRequest
PolicyEngine	Access control, rate limiting, validation
RouteEngine	Decide which plugin/entry to call
PluginInvoker	Execute the actual plugin call
ResponseSerializer	Convert result back to external protocol format

Creating an Adapter

from plugin.sdk.plugin import neko_plugin, plugin_entry, lifecycle, Ok, Err, SdkError
from plugin.sdk.adapter import (
    AdapterGatewayCore, DefaultPolicyEngine, NekoAdapterPlugin,
)
from plugin.sdk.adapter.gateway_models import ExternalRequest

@neko_plugin
class MyProtocolAdapter(NekoAdapterPlugin):
    def __init__(self, ctx):
        super().__init__(ctx)
        self.gateway = None

    @lifecycle(id="startup")
    async def startup(self, **_):
        self.gateway = AdapterGatewayCore(
            normalizer=MyNormalizer(),
            policy_engine=DefaultPolicyEngine(),
            route_engine=MyRouteEngine(),
            invoker=MyInvoker(self.ctx),
            serializer=MySerializer(),
            logger=self.logger,
        )
        return Ok({"status": "ready"})

    @plugin_entry(id="handle_request")
    async def handle_request(self, raw_data: dict, **_):
        external = ExternalRequest(protocol="my_protocol", raw=raw_data)
        response = await self.gateway.process(external)
        return Ok(response.to_dict())

Adapter Modes

Mode	Description
GATEWAY	Full pipeline processing
ROUTER	Route-only (skip policy)
BRIDGE	Direct pass-through
HYBRID	Mode selected per-request

Built-in Reference: MCP Adapter

See plugin/plugins/mcp_adapter/ for a complete adapter implementation that bridges MCP protocol to N.E.K.O plugins. It demonstrates:

• Custom normalizer (MCPRequestNormalizer)
• Custom route engine (MCPRouteEngine)
• Custom invoker (MCPPluginInvoker)
• Custom serializer (MCPResponseSerializer)
• Custom transport (MCPTransportAdapter)

Async Programming

Runtime entry points must use async def. Synchronous helpers remain supported, but expose them through an async entry:

@plugin_entry(id="async_task")
async def async_task(self, url: str, **_):
    async with aiohttp.ClientSession() as session:
        async with session.get(url) as response:
            return Ok({"data": await response.json()})

---

Thread Safety

Timer tasks run in separate threads. Protect shared state:

import threading

@neko_plugin
class ThreadSafePlugin(NekoPluginBase):
    def __init__(self, ctx):
        super().__init__(ctx)
        self._lock = threading.Lock()
        self._counter = 0

    @plugin_entry(id="increment")
    async def increment(self, **_):
        with self._lock:
            self._counter += 1
            return Ok({"count": self._counter})

    @timer_interval(id="report", seconds=60, auto_start=True)
    async def report(self, **_):
        with self._lock:
            count = self._counter
        self.report_status({"count": count})