♻️ 大幅重构，拆分模块，增加一些MCP相关限制

nonebot_plugin_llmchat/dispatcher.py

@@ -0,0 +1,66 @@
+import asyncio
+from collections.abc import Awaitable, Callable
+from typing import Any
+
+from nonebot import logger
+
+from .state import ChatState
+
+EventProcessor = Callable[[int, bool, ChatState, Any], Awaitable[None]]
+
+
+class MessageDispatcher:
+    """每个会话只运行一个worker，并可靠接管竞态窗口中新入队的消息。"""
+
+    def __init__(self, processor: EventProcessor):
+        self._processor = processor
+        self._tasks: set[asyncio.Task[None]] = set()
+        self._closing = False
+
+    async def enqueue(self, context_id: int, is_group: bool, state: ChatState, event: Any) -> None:
+        if self._closing:
+            return
+        await state.queue.put(event)
+        async with state.worker_lock:
+            if state.worker_task is None or state.worker_task.done():
+                self._start_worker(context_id, is_group, state)
+
+    def _start_worker(self, context_id: int, is_group: bool, state: ChatState) -> None:
+        task = asyncio.create_task(
+            self._run_worker(context_id, is_group, state),
+            name=f"llmchat:{'group' if is_group else 'private'}:{context_id}",
+        )
+        state.worker_task = task
+        self._tasks.add(task)
+        task.add_done_callback(self._tasks.discard)
+
+    async def _run_worker(self, context_id: int, is_group: bool, state: ChatState) -> None:
+        current_task = asyncio.current_task()
+        try:
+            while True:
+                try:
+                    event = state.queue.get_nowait()
+                except asyncio.QueueEmpty:
+                    break
+                try:
+                    await self._processor(context_id, is_group, state, event)
+                except asyncio.CancelledError:
+                    raise
+                except Exception:
+                    logger.exception(f"处理会话 {context_id} 的消息失败")
+                finally:
+                    state.queue.task_done()
+        finally:
+            async with state.worker_lock:
+                if state.worker_task is current_task:
+                    state.worker_task = None
+                if not self._closing and not state.queue.empty():
+                    self._start_worker(context_id, is_group, state)
+
+    async def shutdown(self) -> None:
+        self._closing = True
+        tasks = list(self._tasks)
+        for task in tasks:
+            task.cancel()
+        if tasks:
+            await asyncio.gather(*tasks, return_exceptions=True)