feat: add governed customer service agent

app/service/agent_run_application_service.py

@@ -1,5 +1,6 @@
 import hashlib
 import json
+from collections.abc import Sequence
 from dataclasses import dataclass
 from datetime import UTC, datetime, timedelta
 from uuid import uuid4
@@ -20,6 +21,7 @@ from app.model.platform import AgentRun, RequestIdempotency
 from app.model.session import ConversationSession
 from app.repository.outbox_repository import OutboxRepository
 from app.service.agent.bootstrap import get_agent_factory
+from app.service.agent.customer_service_routing import CustomerServiceIntentRouter
 from app.service.agent.factory import AgentFactory
 
 
@@ -30,6 +32,20 @@ class RunAccepted:
     status: str = "queued"
 
 
+def build_outbox_metadata(
+    request: AgentRequest, prior_user_messages: Sequence[str]
+) -> dict[str, object]:
+    """构造 Worker 使用的内部元数据，不信任外部传入的闲聊计数。"""
+    metadata = request.metadata
+    if request.agent_type == "customer_service":
+        metadata = metadata.model_copy(update={
+            "chitchat_streak": CustomerServiceIntentRouter.chitchat_streak(
+                prior_user_messages, request.message
+            )
+        })
+    return metadata.model_dump(mode="json")
+
+
 class AgentRunApplicationService:
     def __init__(self, session: AsyncSession, factory: AgentFactory | None = None) -> None:
         self.session = session
@@ -89,6 +105,20 @@ class AgentRunApplicationService:
                     raise RuntimeError("idempotency record has no run")
                 return RunAccepted(run.run_id, run.trace_id, run.status)
 
+            # 仅读取当前会话最近三条用户消息；第四条闲聊即触发一次自然业务引导。
+            prior_user_messages = list(await self.session.scalars(
+                select(ConversationMessage.content)
+                .where(
+                    ConversationMessage.session_id == request.session_id,
+                    ConversationMessage.role == "user",
+                )
+                .order_by(ConversationMessage.id.desc())
+                .limit(3)
+            ))
+            outbox_metadata = build_outbox_metadata(
+                request, tuple(reversed(prior_user_messages))
+            )
+
             trace_id = context.trace_id
             message = ConversationMessage(
                 session_id=request.session_id, customer_id=user_id, portal="api",
@@ -121,7 +151,7 @@ class AgentRunApplicationService:
                 payload={
                     "run_id": run_id,
                     "actor_type": "visitor" if "visitor" in context.roles else "authenticated",
-                    "metadata": request.metadata.model_dump(mode="json"),
+                    "metadata": outbox_metadata,
                 },
                 occurred_at=now,
             ))