diff --git a/app/services/compare_alert_format.py b/app/services/compare_alert_format.py
index 661c581..49ed3cc 100644
--- a/app/services/compare_alert_format.py
+++ b/app/services/compare_alert_format.py
@@ -128,6 +128,18 @@ def _cost_cell(total_ms: int | None, step_count: int | None) -> str:
     return " / ".join(parts) or "-"
 
 
+def _build_card(title_text: str, elements: list[dict]) -> dict:
+    """组装 schema 2.0 红色 header 卡片;三条路径只需决定 elements。"""
+    return {
+        "schema": "2.0",
+        "header": {
+            "title": {"tag": "plain_text", "content": title_text},
+            "template": "red",
+        },
+        "body": {"elements": elements},
+    }
+
+
 def _build_table_rows(
     hits: list[AlertHit],
     *,
@@ -137,7 +149,9 @@ def _build_table_rows(
     """按 _TYPE_ORDER 顺序展开，每类型最多 max_detail_per_type 条。"""
     grouped: dict[str, list[AlertHit]] = {t: [] for t in _TYPE_ORDER}
     for h in hits:
-        grouped.setdefault(h.alert_type, []).append(h)
+        if h.alert_type in grouped:
+            grouped[h.alert_type].append(h)
+        # 非 _TYPE_ORDER 类型静默跳过(与既有行为一致)
 
     rows = []
     for t in _TYPE_ORDER:
@@ -193,16 +207,7 @@ def format_alert_card(
     # ---------- 空 hits ----------
     if total == 0:
         md_content = f"数据范围：近 {interval_min} 分钟\n本期无异常"
-        return {
-            "schema": "2.0",
-            "header": {
-                "title": {"tag": "plain_text", "content": title_text},
-                "template": "red",
-            },
-            "body": {
-                "elements": [{"tag": "markdown", "content": md_content}],
-            },
-        }
+        return _build_card(title_text, [{"tag": "markdown", "content": md_content}])
 
     # ---------- 摘要 ----------
     grouped_count: dict[str, int] = {}
@@ -221,16 +226,7 @@ def format_alert_card(
     # ---------- 截断：超 max_total 只出摘要 ----------
     if total > max_total:
         md_content += f"\n超 {max_total} 条仅列计数，明细见分析库 comparison_record"
-        return {
-            "schema": "2.0",
-            "header": {
-                "title": {"tag": "plain_text", "content": title_text},
-                "template": "red",
-            },
-            "body": {
-                "elements": [{"tag": "markdown", "content": md_content}],
-            },
-        }
+        return _build_card(title_text, [{"tag": "markdown", "content": md_content}])
 
     # ---------- 常规：摘要 + table ----------
     rows = _build_table_rows(hits, phone_map=phone_map, max_detail_per_type=max_detail_per_type)
@@ -242,16 +238,4 @@ def format_alert_card(
         "columns": _TABLE_COLUMNS,
         "rows": rows,
     }
-    return {
-        "schema": "2.0",
-        "header": {
-            "title": {"tag": "plain_text", "content": title_text},
-            "template": "red",
-        },
-        "body": {
-            "elements": [
-                {"tag": "markdown", "content": md_content},
-                table_element,
-            ],
-        },
-    }
+    return _build_card(title_text, [{"tag": "markdown", "content": md_content}, table_element])