feat: implement channel runtime connectors

app-instance/backend/beaver/interfaces/channels/base.py

@@ -2,16 +2,17 @@
 
 from __future__ import annotations
 
-from typing import Protocol
+from typing import Any, Protocol
 
-from beaver.foundation.events import MessageBus, OutboundMessage
+from beaver.foundation.events import InboundMessage, OutboundMessage
 
 
 class ChannelAdapter(Protocol):
-    """Minimal contract every gateway channel must implement."""
+    """Minimal contract every runtime channel adapter must implement."""
 
-    name: str
-    bus: MessageBus
+    channel_id: str
+    kind: str
+    mode: str
 
     async def start(self) -> None:
         """Prepare the channel before messages are routed."""
@@ -22,3 +23,9 @@ class ChannelAdapter(Protocol):
     async def send(self, message: OutboundMessage) -> None:
         """Deliver an outbound message to the concrete channel."""
 
+
+class ChannelInboundSink(Protocol):
+    """Runtime callback used by adapters to submit normalized inbound messages."""
+
+    async def accept_inbound(self, message: InboundMessage) -> Any:
+        """Accept a normalized inbound message from an adapter."""