refactor(ai): 模組化重構 - NVIDIA chat 移至 NvidiaProvider

符合 feedback_lewooogo_modular_enforcement.md 規範:
- 移除 openclaw.py 中的 _call_nvidia() (重複邏輯)
- 新增 NvidiaProvider.chat() 方法
- 更新 INvidiaProvider Protocol
- openclaw.py 改用 get_nvidia_provider().chat()
- 測試移至 test_nvidia_chat.py

架構層次:
- Router → Service → Provider (正確)
- 禁止 Service 層重複實作已存在的 Provider 功能

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/tests/test_nvidia_chat.py

@@ -1,37 +1,39 @@
 """
-test_openclaw_nvidia.py - NVIDIA RCA 整合測試
+test_nvidia_chat.py - NvidiaProvider.chat() 測試
 
-2026-03-29 ogt: P0 修復 - 新增 _call_nvidia 測試
+2026-03-29 ogt: 模組化重構 - 測試移至 NvidiaProvider
+符合 feedback_lewooogo_modular_enforcement.md 規範
 
 測試策略 (遵循 feedback_no_mock_testing.md):
 - 使用真實 NVIDIA API (需 NVIDIA_API_KEY)
 - 跳過條件: 無 API Key 時跳過
 """
 
-import pytest
+import json
 import os
 
-from src.services.openclaw import OpenClawService
-from src.core.config import get_settings
+import pytest
 
+from src.core.config import get_settings
+from src.services.nvidia_provider import NvidiaProvider, get_nvidia_provider
 
 settings = get_settings()
 
 
 @pytest.fixture
-def openclaw_service():
-    """建立 OpenClawService 實例"""
-    return OpenClawService()
+def nvidia_provider():
+    """建立 NvidiaProvider 實例"""
+    return NvidiaProvider()
 
 
 @pytest.mark.asyncio
 @pytest.mark.skipif(
     not os.getenv("NVIDIA_API_KEY") and not settings.NVIDIA_API_KEY,
-    reason="NVIDIA_API_KEY not configured"
+    reason="NVIDIA_API_KEY not configured",
 )
-async def test_call_nvidia_success(openclaw_service):
+async def test_chat_success(nvidia_provider):
     """
-    測試 _call_nvidia 成功回應
+    測試 chat() 成功回應
 
     驗證:
     - 回應格式正確 (4-tuple)
@@ -43,7 +45,7 @@ async def test_call_nvidia_success(openclaw_service):
     {"status": "ok", "message": "test"}
     只回傳 JSON，不要其他內容。"""
 
-    response, success, total_tokens, cost_usd = await openclaw_service._call_nvidia(prompt)
+    response, success, total_tokens, cost_usd = await nvidia_provider.chat(prompt)
 
     assert success is True, f"Expected success, got error: {response}"
     assert isinstance(response, str)
@@ -53,7 +55,7 @@ async def test_call_nvidia_success(openclaw_service):
 
 
 @pytest.mark.asyncio
-async def test_call_nvidia_no_api_key(openclaw_service, monkeypatch):
+async def test_chat_no_api_key():
     """
     測試無 API Key 時的處理
 
@@ -61,10 +63,10 @@ async def test_call_nvidia_no_api_key(openclaw_service, monkeypatch):
     - success = False
     - 回傳適當錯誤訊息
     """
-    # 暫時移除 API Key
-    monkeypatch.setattr(settings, "NVIDIA_API_KEY", None)
+    # 建立沒有 API Key 的 provider
+    provider = NvidiaProvider(api_key=None)
 
-    response, success, total_tokens, cost_usd = await openclaw_service._call_nvidia("test")
+    response, success, total_tokens, cost_usd = await provider.chat("test")
 
     assert success is False
     assert "not configured" in response.lower()
@@ -75,23 +77,21 @@ async def test_call_nvidia_no_api_key(openclaw_service, monkeypatch):
 @pytest.mark.asyncio
 @pytest.mark.skipif(
     not os.getenv("NVIDIA_API_KEY") and not settings.NVIDIA_API_KEY,
-    reason="NVIDIA_API_KEY not configured"
+    reason="NVIDIA_API_KEY not configured",
 )
-async def test_call_nvidia_json_response(openclaw_service):
+async def test_chat_json_response(nvidia_provider):
     """
     測試 JSON 格式回應
 
     驗證:
     - 回應是有效 JSON
     """
-    import json
-
     prompt = """回傳一個 JSON 物件，包含:
     - action: "NO_ACTION"
     - reason: "測試"
     只回傳 JSON。"""
 
-    response, success, _, _ = await openclaw_service._call_nvidia(prompt)
+    response, success, _, _ = await nvidia_provider.chat(prompt)
 
     assert success is True
 
@@ -106,9 +106,9 @@ async def test_call_nvidia_json_response(openclaw_service):
 @pytest.mark.asyncio
 @pytest.mark.skipif(
     not os.getenv("NVIDIA_API_KEY") and not settings.NVIDIA_API_KEY,
-    reason="NVIDIA_API_KEY not configured"
+    reason="NVIDIA_API_KEY not configured",
 )
-async def test_call_nvidia_uses_model_registry(openclaw_service):
+async def test_chat_uses_model_registry(nvidia_provider):
     """
     測試使用 ModelRegistry 取得模型
 
@@ -123,3 +123,37 @@ async def test_call_nvidia_uses_model_registry(openclaw_service):
     # 模型應該是 llama-3.1-nemotron-70b-instruct
     assert "nemotron" in expected_model.lower()
     assert "70b" in expected_model or "mini" in expected_model
+
+
+@pytest.mark.asyncio
+def test_get_nvidia_provider_singleton():
+    """
+    測試單例模式
+
+    驗證:
+    - get_nvidia_provider() 返回同一實例
+    """
+    provider1 = get_nvidia_provider()
+    provider2 = get_nvidia_provider()
+
+    assert provider1 is provider2
+
+
+@pytest.mark.asyncio
+@pytest.mark.skipif(
+    not os.getenv("NVIDIA_API_KEY") and not settings.NVIDIA_API_KEY,
+    reason="NVIDIA_API_KEY not configured",
+)
+async def test_chat_includes_otel_tracing(nvidia_provider):
+    """
+    測試 OTEL 追蹤整合
+
+    驗證:
+    - chat() 執行時有 OTEL span
+    """
+    # 這個測試主要驗證代碼不會拋出異常
+    prompt = '{"test": true}'
+    response, success, _, _ = await nvidia_provider.chat(prompt)
+
+    # 只要沒有拋出異常就算通過
+    assert isinstance(response, str)