feat: raise configurable chat tool call limit

backend/tests/test_chat_agent.py

@@ -218,8 +218,9 @@ def test_sse_persists_messages_and_tool_failure(session_factory, monkeypatch):
         def tool_call(self, messages, tools):
             calls.append(messages)
             if len(calls) == 1:
-                return {"role": "assistant", "content": None, "tool_calls": [{"id": "call1", "type": "function",
-                    "function": {"name": "list_courses", "arguments": "{}"}}]}
+                return {"role": "assistant", "content": None, "tool_calls": [
+                    {"id": f"call{index}", "type": "function",
+                     "function": {"name": "list_courses", "arguments": "{}"}} for index in range(9)]}
             return {"role": "assistant", "content": "已列出课程版本。", "tool_calls": []}
     monkeypatch.setattr(chat_api, "client_for_chat", lambda db: FakeClient())
     def override_db():
@@ -231,9 +232,10 @@ def test_sse_persists_messages_and_tool_failure(session_factory, monkeypatch):
         created = client.post("/api/conversations", json={"title": "测试对话"}).json()
         with client.stream("POST", f"/api/conversations/{created['id']}/messages", json={"content": "列出课程"}) as response:
             body = "".join(response.iter_text())
-        assert "event: tool" in body and "event: message" in body
+        assert body.count("event: tool") == 9 and "event: message" in body
         restored = client.get(f"/api/conversations/{created['id']}").json()
         assert [m["role"] for m in restored["messages"]] == ["user", "assistant"]
+        assert len(restored["messages"][1]["tool_calls"]) == 9
         assert restored["runs"][0]["status"] == "completed"
         monkeypatch.setattr(chat_api, "client_for_chat", lambda db: (_ for _ in ()).throw(ModelError("不支持工具调用")))
         with client.stream("POST", f"/api/conversations/{created['id']}/messages", json={"content": "再试"}) as response:
@@ -251,6 +253,35 @@ def test_sse_persists_messages_and_tool_failure(session_factory, monkeypatch):
         app.dependency_overrides.clear()
 
 
+def test_failed_tool_calls_count_toward_limit(monkeypatch):
+    class RepeatingClient:
+        def tool_call(self, messages, tools):
+            return {"role": "assistant", "content": None, "tool_calls": [
+                {"id": f"call{len(messages)}", "type": "function",
+                 "function": {"name": "unknown_tool", "arguments": "{}"}}]}
+
+    conversation = SimpleNamespace(id=1, course_version_id=None, batch_id=None, project_id=None, updated_at=None)
+    run = SimpleNamespace(id=1, status="running", error=None, finished_at=None)
+    class FakeSession:
+        def __enter__(self):
+            return self
+        def __exit__(self, *_args):
+            pass
+        def get(self, model, _id):
+            return conversation if model is Conversation else run
+        def scalars(self, _query):
+            return SimpleNamespace(all=lambda: [])
+        def commit(self):
+            pass
+
+    monkeypatch.setattr(chat_api, "client_for_chat", lambda db: RepeatingClient())
+    monkeypatch.setattr(chat_api, "get_settings", lambda: SimpleNamespace(chat_max_tool_calls=9))
+    body = "".join(chat_api._run_agent(FakeSession, 1, 1, "循环调用工具"))
+    assert body.count("event: tool") == 9
+    assert "本次消息工具调用超过上限 9 次" in body
+    assert run.status == "failed"
+
+
 def test_native_tool_calls_unsupported_endpoint():
     transport = httpx.MockTransport(lambda request: httpx.Response(400, json={"error": "unsupported"}))
     client = DeepSeekClient(api_key="test-key", transport=transport)