diff --git a/apps/api/src/services/ai_router.py b/apps/api/src/services/ai_router.py
index b112799f..f4d14206 100644
--- a/apps/api/src/services/ai_router.py
+++ b/apps/api/src/services/ai_router.py
@@ -398,7 +398,14 @@ class AIRouter:
         provider_override = self._intent_provider_overrides.get(intent)
         if provider_override is not None:
             provider = provider_override
-            model = self._provider_models[provider]
+            # 2026-04-03 ogt: DIAGNOSE/ALERT_TRIAGE 用 summary model (llama3.2:3b)
+            # 避免 qwen2.5:7b-instruct 90秒 timeout 導致全鏈路失敗 (Phase 24 A選項)
+            if provider == AIProviderEnum.OLLAMA and intent in (
+                IntentType.DIAGNOSE, IntentType.ALERT_TRIAGE, IntentType.QUERY
+            ):
+                model = self._ollama_summary
+            else:
+                model = self._provider_models[provider]
             reason = f"意圖 {intent.value} 指定使用 {provider.value}"
             return provider, model, reason