feat: connect chat endpoint to verified retrieval

backend/app/api/routes/chat.py

@@ -1,15 +1,34 @@
-from fastapi import APIRouter
+from fastapi import APIRouter, Depends
+from sqlalchemy.orm import Session
 
+from app.db.session import get_db
 from app.schemas.chat import ChatRequest, ChatResponse
+from app.schemas.retrieval import RetrievalRequest
+from app.services.retrieval import retrieve
 
 router = APIRouter(tags=["chat"])
 
 
 @router.post("/chat", response_model=ChatResponse)
-def chat(payload: ChatRequest) -> ChatResponse:
-    # TODO: retrieval -> context assembly -> LLM -> evidence/source checks
+def chat(payload: ChatRequest, db: Session = Depends(get_db)) -> ChatResponse:
+    """运行可复核的关键词检索；模型未配置时绝不伪造生成式回答。"""
+    result = retrieve(db, RetrievalRequest(query=payload.question, top_k=5))
+    if result.status == "no_evidence":
+        return ChatResponse(
+            answer="未检索到可用的已核验知识依据。请补充更具体的关键词，或由管理员补充并审核资料。",
+            status="no_evidence",
+            sources=[],
+            retrieval_run_id=result.run_id,
+        )
     return ChatResponse(
-        answer=f"已收到问题：{payload.question}。当前为基础壳子，尚未接入知识检索或大语言模型。",
-        status="stub",
-        sources=[],
+        answer=(
+            f"已检索到 {result.total_hits} 条已核验知识依据。当前尚未配置大语言模型，"
+            "因此系统仅返回可追溯证据，不生成或改写答案。"
+        ),
+        status="retrieval_only",
+        sources=[
+            {"title": hit.title, "source_url": hit.source_url}
+            for hit in result.results
+        ],
+        retrieval_run_id=result.run_id,
     )

backend/app/schemas/chat.py

@@ -1,3 +1,6 @@
+from typing import Literal
+from uuid import UUID
+
 from pydantic import BaseModel, Field
 
 
@@ -12,5 +15,6 @@ class SourcePreview(BaseModel):
 
 class ChatResponse(BaseModel):
     answer: str
-    status: str
+    status: Literal["retrieval_only", "no_evidence"]
     sources: list[SourcePreview] = []
+    retrieval_run_id: UUID

backend/tests/test_auth.py

@@ -271,7 +271,9 @@ def test_all_management_routes_require_admin_and_history_is_private(anonymous_cl
     for method, path in paths:
         assert c.request(method, path, json={}).status_code == 403, path
     assert c.post("/api/retrieval", json={"query": "占位"}).json()["status"] == "no_evidence"
-    assert c.post("/api/chat", json={"question": "占位"}).json()["status"] == "stub"
+    response = c.post("/api/chat", json={"question": "占位"})
+    assert response.status_code == 200
+    assert response.json()["status"] == "no_evidence"
 
 
 def test_admin_access_live_role_and_no_csrf_bypass(client, migrated_database):

backend/tests/test_catalog.py

@@ -59,12 +59,28 @@ def review(client, item, status="verified"):
     )
 
 
-def test_health_docs_and_stub(client):
+def test_health_docs_and_chat_without_evidence(client):
     assert client.get("/api/health").json()["status"] == "ok"
     assert client.get("/api/ready").json()["database"] == "connected"
     assert client.get("/docs").status_code == 200
     assert "/api/knowledge/{item_id}/review" in client.get("/openapi.json").json()["paths"]
-    assert client.post("/api/chat", json={"question": "测试"}).json()["status"] == "stub"
+    response = client.post("/api/chat", json={"question": "测试"})
+    assert response.status_code == 200
+    assert response.json()["status"] == "no_evidence"
+
+
+def test_chat_returns_real_retrieval_evidence_without_generation(client):
+    item = knowledge(client, title="那拉提测试资料", content="那拉提文旅服务测试依据")
+    assert review(client, item).status_code == 200
+
+    response = client.post("/api/chat", json={"question": "那拉提文旅服务"})
+
+    assert response.status_code == 200
+    body = response.json()
+    assert body["status"] == "retrieval_only"
+    assert "不生成" in body["answer"]
+    assert body["retrieval_run_id"]
+    assert body["sources"] == [{"title": "那拉提测试资料", "source_url": "https://example.com/"}]
 
 
 def test_legacy_create_and_missing_evidence(client):