agent: use ContextVar for tool routing context

nanobot/agent/tools/message.py

@@ -1,5 +1,6 @@
 """Message tool for sending messages to users."""
 
+from contextvars import ContextVar
 from typing import Any, Awaitable, Callable
 
 from nanobot.agent.tools.base import Tool, tool_parameters
@@ -30,16 +31,19 @@ class MessageTool(Tool):
         default_message_id: str | None = None,
     ):
         self._send_callback = send_callback
-        self._default_channel = default_channel
-        self._default_chat_id = default_chat_id
-        self._default_message_id = default_message_id
-        self._sent_in_turn: bool = False
+        self._default_channel: ContextVar[str] = ContextVar("message_default_channel", default=default_channel)
+        self._default_chat_id: ContextVar[str] = ContextVar("message_default_chat_id", default=default_chat_id)
+        self._default_message_id: ContextVar[str | None] = ContextVar(
+            "message_default_message_id",
+            default=default_message_id,
+        )
+        self._sent_in_turn_var: ContextVar[bool] = ContextVar("message_sent_in_turn", default=False)
 
     def set_context(self, channel: str, chat_id: str, message_id: str | None = None) -> None:
         """Set the current message context."""
-        self._default_channel = channel
-        self._default_chat_id = chat_id
-        self._default_message_id = message_id
+        self._default_channel.set(channel)
+        self._default_chat_id.set(chat_id)
+        self._default_message_id.set(message_id)
 
     def set_send_callback(self, callback: Callable[[OutboundMessage], Awaitable[None]]) -> None:
         """Set the callback for sending messages."""
@@ -49,6 +53,14 @@ class MessageTool(Tool):
         """Reset per-turn send tracking."""
         self._sent_in_turn = False
 
+    @property
+    def _sent_in_turn(self) -> bool:
+        return self._sent_in_turn_var.get()
+
+    @_sent_in_turn.setter
+    def _sent_in_turn(self, value: bool) -> None:
+        self._sent_in_turn_var.set(value)
+
     @property
     def name(self) -> str:
         return "message"
@@ -73,16 +85,19 @@ class MessageTool(Tool):
     ) -> str:
         from nanobot.utils.helpers import strip_think
         content = strip_think(content)
-        
-        channel = channel or self._default_channel
-        chat_id = chat_id or self._default_chat_id
+
+        default_channel = self._default_channel.get()
+        default_chat_id = self._default_chat_id.get()
+
+        channel = channel or default_channel
+        chat_id = chat_id or default_chat_id
         # Only inherit default message_id when targeting the same channel+chat.
         # Cross-chat sends must not carry the original message_id, because
         # some channels (e.g. Feishu) use it to determine the target
         # conversation via their Reply API, which would route the message
         # to the wrong chat entirely.
-        if channel == self._default_channel and chat_id == self._default_chat_id:
-            message_id = message_id or self._default_message_id
+        if channel == default_channel and chat_id == default_chat_id:
+            message_id = message_id or self._default_message_id.get()
         else:
             message_id = None
 
@@ -104,7 +119,7 @@ class MessageTool(Tool):
 
         try:
             await self._send_callback(msg)
-            if channel == self._default_channel and chat_id == self._default_chat_id:
+            if channel == default_channel and chat_id == default_chat_id:
                 self._sent_in_turn = True
             media_info = f" with {len(media)} attachments" if media else ""
             return f"Message sent to {channel}:{chat_id}{media_info}"