move ui background message suppression into agent context

app/core/message_context.py

@@ -1,26 +0,0 @@
-import contextvars
-from contextlib import contextmanager
-from typing import Iterator
-
-_suppress_message_channel = contextvars.ContextVar(
-    "suppress_message_channel", default=False
-)
-
-
-def is_message_channel_suppressed() -> bool:
-    """
-    当前上下文是否禁止向外部消息渠道派发通知。
-    """
-    return bool(_suppress_message_channel.get())
-
-
-@contextmanager
-def suppress_message_channel() -> Iterator[None]:
-    """
-    在当前上下文中临时禁用外部消息渠道派发。
-    """
-    token = _suppress_message_channel.set(True)
-    try:
-        yield
-    finally:
-        _suppress_message_channel.reset(token)