feat(chat): support chat resources, implement chat-based remote discovery via resource messages

backend/src/agent.py

@@ -85,11 +85,19 @@ class Agent:
         chat_view = await self.app.get_chat_view(message.chat_id)
         thread = chat_view.get_thread(message.thread_id)
 
+        remotes = []
         messages = []
         for msg in thread.messages:
             role = self._role_for_message(msg)
             messages.append({"role": role, "content": msg.content})
 
+        for msg in thread.resources:
+            # Remote declarations: content is the remote name
+            if msg.subkind == 'remote':
+                name = msg.content
+                if (self.user_id, name) in self.app.remotes and name not in remotes:
+                    remotes.append(name)
+
         run = AgentRun.create(
             self.app,
             agent_id=self.id,
@@ -98,6 +106,7 @@ class Agent:
                 "messages": messages,
                 "chat_id": message.chat_id,
                 "thread_id": message.thread_id,
+                "remotes": remotes,
             },
         )