fix(monitoring): classify host memory pressure accurately

scripts/cold_start_playbooks.py

@@ -104,18 +104,18 @@ PLAYBOOK_TEMPLATES = [
         "severity_range": ["P2", "P3"],
     },
     {
-        "name": "節點記憶體不足 — 清理 Cache",
-        "alert_type": "HostOutOfMemory",
-        "description": "主機記憶體不足，清理 Page Cache 釋放空間",
+        "name": "節點記憶體壓力 — 唯讀診斷",
+        "alert_type": "HostMemoryUsageHigh",
+        "description": "主機 MemAvailable 偏低；先驗證 OOM、swap、程序與服務狀態，不做破壞性快取清理",
         "category": "infrastructure",
         "repair_steps": [
-            {"command": "ssh {target} 'free -h'", "purpose": "確認記憶體狀況"},
-            {"command": "ssh {target} 'sudo sync && sudo sysctl vm.drop_caches=3'", "purpose": "清理 Page Cache"},
-            {"command": "ssh {target} 'free -h'", "purpose": "確認記憶體已釋放"},
+            {"command": "ssh {target} 'free -h'", "purpose": "讀取 MemAvailable 與 swap 狀況"},
+            {"command": "ssh {target} \"awk '$1 == \\\"oom_kill\\\" { print }' /proc/vmstat\"", "purpose": "確認 kernel OOM kill 累計值"},
+            {"command": "ssh {target} 'ps aux --sort=-%mem | head -20'", "purpose": "讀取主要記憶體程序"},
         ],
         "estimated_minutes": 5,
-        "symptom_alertnames": ["HostOutOfMemory", "NodeMemoryPressure"],
-        "severity_range": ["P1", "P2"],
+        "symptom_alertnames": ["HostMemoryUsageHigh", "HostOutOfMemory", "NodeMemoryPressure"],
+        "severity_range": ["P2", "P3"],
     },
     {
         "name": "磁碟使用率過高 — 清理舊日誌",