feat(ai-router): DIAGNOSE intent override 升級至 Nemotron (P0)

apps/api/src/services/ai_router.py

@@ -260,9 +260,9 @@ class AIRouter:
             IntentType.RESTART: None,  # 依複雜度
             IntentType.SCALE: None,  # 依複雜度
             IntentType.CONFIG: None,  # 依複雜度 (但 HIGH 會升級)
-            # 2026-04-04 ogt: Phase 25 P0 — DIAGNOSE 改為 NEMOTRON (NIM 188)
-            # 原因: 零費用本地 NIM + 高能力; 搭配 _local_fallback_chain 保證不觸碰雲端
-            IntentType.DIAGNOSE: AIProviderEnum.NEMOTRON,  # 診斷優先 NIM 本地 (隱私)
+            # P0 2026-04-04 Claude Code: DIAGNOSE 升級至 Nemotron（高能力雲端）
+            # 注意: FORCE_LOCAL 情境由 require_local=True + privacy 過濾保護，Nemotron 會被正確跳過
+            IntentType.DIAGNOSE: AIProviderEnum.NEMOTRON,
             # 輔助意圖
             IntentType.DELETE: AIProviderEnum.CLAUDE,  # CRITICAL → 強制 Claude
             IntentType.ROLLBACK: None,  # 依複雜度

apps/api/tests/test_p0_diagnose_routing.py

@@ -136,3 +136,18 @@ class TestLocalFallbackChain:
 
         assert result.success is False
         assert result.error == "local_providers_unavailable"
+
+
+class TestDiagnoseIntentOverride:
+    """DIAGNOSE intent 應優先路由至 Nemotron（非 FORCE_LOCAL 情境）"""
+
+    def test_diagnose_override_is_nemotron(self):
+        """_intent_provider_overrides[DIAGNOSE] 應為 NEMOTRON"""
+        from src.services.ai_router import AIRouter, AIProviderEnum
+        from src.services.intent_classifier import IntentType
+
+        router = AIRouter()
+        override = router._intent_provider_overrides.get(IntentType.DIAGNOSE)
+        assert override == AIProviderEnum.NEMOTRON, (
+            f"DIAGNOSE 應路由至 NEMOTRON，實際為 {override}"
+        )