feat: send agent prompt -> prompt agent

backend/src/app_mixins/agent.py

@@ -180,10 +180,15 @@ class AgentMixin:
             runs = [r for r in runs if r.user_id == user_id]
         return [r.serialize() for r in runs]
 
-    async def send_agent_prompt(self, agent_id, instruction, input=None, options={}):
+    async def prompt_agent(self, agent_id, instruction, input=None, options={}):
+        # Mirror agent.prompt's generator so run ownership and lifecycle stay
+        # inside the mixin: callers just iterate and receive the same raw
+        # inference.Message objects. get_agent_control is awaited lazily on first
+        # iteration, keeping the control object alive for the generator's
+        # lifetime.
         control = await self.get_agent_control(agent_id)
-        response = await control.prompt(instruction, input, **options)
-        return response
+        async for msg in control.prompt(instruction, input, **options):
+            yield msg
 
     async def call_agent_action(self, agent_id, action, args):
         control = await self.get_agent_control(agent_id)