diff --git a/apps/api/src/services/model_registry.py b/apps/api/src/services/model_registry.py
index 49f6db71c..e8affbb02 100644
--- a/apps/api/src/services/model_registry.py
+++ b/apps/api/src/services/model_registry.py
@@ -124,11 +124,12 @@ class ModelRegistry:
                         "summary": "llama3.2:3b",
                     }
                 },
+                # 2026-03-28 ogt: 更新到 gemini-2.0-flash (1.5 已停用)
                 "gemini": {
                     "models": {
-                        "default": "gemini-1.5-flash",
-                        "rca": "gemini-1.5-flash",
-                        "summary": "gemini-1.5-flash",
+                        "default": "gemini-2.0-flash",
+                        "rca": "gemini-2.0-flash",
+                        "summary": "gemini-2.0-flash",
                     }
                 },
                 "claude": {
@@ -176,9 +177,10 @@ class ModelRegistry:
 
         if not model:
             # 最終 fallback
+            # 2026-03-28 ogt: 更新 gemini-2.0-flash
             fallback_map = {
                 "ollama": "qwen2.5:7b-instruct",
-                "gemini": "gemini-1.5-flash",
+                "gemini": "gemini-2.0-flash",
                 "claude": "claude-3-haiku-20240307",
             }
             model = fallback_map.get(provider, provider)