fix: preserve raw intent across language switching

tests/unit/test_agent_chat_actions.py

@@ -92,6 +92,7 @@ async def test_agent_chat_maps_router_actions_and_passes_context(
             "history": history,
             "session_id": "session-7",
             "job_id": "job-7",
+            "language": "zh",
         }
     ]
     assert result["success"] is True
@@ -108,6 +109,40 @@ async def test_agent_chat_maps_router_actions_and_passes_context(
         assert result["intent"]["stages"] == []
 
 
+@pytest.mark.asyncio
+async def test_agent_chat_keeps_english_language_separate_from_business_query(
+    monkeypatch,
+    web_main,
+):
+    captured = []
+    _install_router(
+        monkeypatch,
+        {
+            "status": "ok",
+            "action": "reply",
+            "message": "I can help with that.",
+            "intent": None,
+            "sources": [],
+            "tool_trace": [],
+        },
+        captured,
+    )
+    request = web_main.AgentChatRequest(
+        message="执行接下来的分析",
+        language="en",
+        session_id="english-business-query",
+        job_id="job-english-business-query",
+        history=[],
+    )
+
+    result = await web_main.agent_chat(request)
+
+    assert result["intent"]["message"] == "I can help with that."
+    assert request.message == "执行接下来的分析"
+    assert captured[0]["query"] == "执行接下来的分析"
+    assert captured[0]["language"] == "en"
+
+
 @pytest.mark.asyncio
 async def test_agent_chat_persists_router_proposal_without_analysis_intent(
     monkeypatch,

tests/unit/test_router_analysis_handoff_boundary.py

@@ -143,3 +143,23 @@ def test_new_analysis_decision_discards_main_agent_workflow_and_clarification()
     assert normalized.workflow_id is None
     assert normalized.clarification_question is None
     assert normalized.analysis_request_kind == "execution"
+
+
+def test_router_response_language_does_not_rewrite_business_query() -> None:
+    query = "执行接下来的分析"
+    messages = RouterRuntime._initial_messages(
+        query=query,
+        history=[],
+        session_id="english-router-session",
+        job_id="job-english-router",
+        decision=RouteDecision(
+            goal="general",
+            needs=[],
+            subject=query,
+        ),
+        goal_ledger=None,
+        language="en",
+    )
+
+    assert messages[-1].content == query
+    assert "Respond to the user in English." in messages[0].content