diff --git a/apps/api/alert_rules.yaml b/apps/api/alert_rules.yaml
index a715a8e0..7d32d0cd 100644
--- a/apps/api/alert_rules.yaml
+++ b/apps/api/alert_rules.yaml
@@ -149,14 +149,18 @@ rules:
         - HostClockSkewDetected
         - HostClockNotSynchronising
     response:
-      action_title: "⚠️ 主機告警 — 需 SSH 人工排查"
-      description: "⚠️ 主機層告警（node_exporter）。此告警源自主機資源，無法透過 kubectl 自動修復。請 SSH 登入主機排查根因：top / htop / df -h / journalctl -xe。"
-      suggested_action: NO_ACTION
-      kubectl_command: ""
+      action_title: "🔍 主機自動診斷 — SSH 收集根因"
+      description: "主機層告警（node_exporter）。自動 SSH 登入主機執行診斷指令，收集 CPU/記憶體/磁碟資訊後回報。"
+      # 2026-04-27 Claude Sonnet 4.6: 從 NO_ACTION 改為自動 SSH 診斷
+      # 根因：SSH_MCP_ALLOWED_HOSTS 空白導致全部降為人工審核（飛輪完全停轉）
+      # 修復：補 SSH_MCP_ALLOWED_HOSTS 白名單 + 改為自動診斷指令（收集不修改，安全）
+      # 診斷原則：只收集資訊，不做任何改動 → risk=low 且不在 _DESTRUCTIVE_PATTERNS 清單
+      suggested_action: SSH_DIAGNOSE
+      kubectl_command: "ssh {host} 'echo \"=== CPU TOP ===\"; ps aux --sort=-%cpu | head -15; echo \"=== MEMORY ===\"; free -h; echo \"=== DISK ===\"; df -h; echo \"=== LOAD ===\"; uptime'"
       estimated_downtime: "N/A"
       risk: low
       responsibility: INFRA
-      reasoning: "[規則匹配] 主機層資源告警無法自動修復，需人工登入確認高負載/高記憶體/磁碟根因後決策。禁止 kubectl restart（node_exporter 不是 K8s 服務）。"
+      reasoning: "[規則匹配] 主機層資源告警，自動 SSH 執行診斷指令（只讀，不修改），收集根因資訊後推送 Telegram 讓 SRE 決策。"
 
   - id: high_cpu
     priority: 40
diff --git a/apps/api/src/plugins/mcp/providers/ssh_provider.py b/apps/api/src/plugins/mcp/providers/ssh_provider.py
index 0237daa0..58477b56 100644
--- a/apps/api/src/plugins/mcp/providers/ssh_provider.py
+++ b/apps/api/src/plugins/mcp/providers/ssh_provider.py
@@ -443,6 +443,15 @@ class SSHProvider(MCPToolProvider):
 
     def _build_command(self, tool_name: str, params: dict) -> str:
         # 所有接受用戶字串的工具，必須先通過 _validate_param() 白名單驗證
+        if tool_name == "ssh_diagnose":
+            # 2026-04-27 Claude Sonnet 4.6: 主機告警自動診斷 — 只讀，不修改任何狀態
+            return (
+                "echo '=== CPU TOP ===' && ps aux --sort=-%cpu | head -15 && "
+                "echo '=== MEMORY ===' && free -h && "
+                "echo '=== DISK ===' && df -h && "
+                "echo '=== LOAD ===' && uptime"
+            )
+
         if tool_name == "ssh_get_top_processes":
             return "ps aux --sort=-%cpu | head -15"
 
diff --git a/apps/api/src/services/auto_approve.py b/apps/api/src/services/auto_approve.py
index f99c072a..0a52f549 100644
--- a/apps/api/src/services/auto_approve.py
+++ b/apps/api/src/services/auto_approve.py
@@ -301,11 +301,19 @@ class AutoApprovePolicy:
         #                          P1-2 改用 NO_EXECUTABLE_ACTION（避免污染 KM 飛輪學習資料）
         _raw_action = proposal_data.get("action", "") or ""
         _kubectl_cmd = proposal_data.get("kubectl_command", "") or ""
-        _has_kubectl = "kubectl" in _raw_action.lower() or "kubectl" in _kubectl_cmd.lower()
-        if not _has_kubectl:
+        # 2026-04-27 Claude Sonnet 4.6: 擴充可執行指令識別，加入 SSH 診斷路徑
+        # 根因：_has_kubectl 只認 kubectl，SSH 診斷指令（主機告警）被全部攔截 → 飛輪停轉
+        # 修復：ssh {host} '...' 格式也是可執行指令，允許走 _ssh_execute() 路徑
+        _has_executable = (
+            "kubectl" in _raw_action.lower()
+            or "kubectl" in _kubectl_cmd.lower()
+            or _raw_action.lower().strip().startswith("ssh ")
+            or _kubectl_cmd.lower().strip().startswith("ssh ")
+        )
+        if not _has_executable:
             return self._reject(
                 reason=AutoApproveReason.NO_EXECUTABLE_ACTION,
-                detail=f"Action '{_raw_action[:60] or _kubectl_cmd[:60]}' is natural language — no kubectl command, requires human review",
+                detail=f"Action '{_raw_action[:60] or _kubectl_cmd[:60]}' is natural language — no kubectl/ssh command, requires human review",
                 risk_level=risk_level,
                 trust_score=trust_score,
                 confidence=confidence,
diff --git a/apps/api/src/services/decision_manager.py b/apps/api/src/services/decision_manager.py
index b8021782..85316bc5 100644
--- a/apps/api/src/services/decision_manager.py
+++ b/apps/api/src/services/decision_manager.py
@@ -3101,6 +3101,9 @@ class DecisionManager:
             return
 
         # 解析 SSH tool + params
+        # 2026-04-27 Claude Sonnet 4.6: 加入主機診斷路徑
+        # 根因：只支援 docker/systemctl restart，主機告警 ssh {host} '...' 格式全降級人工
+        # 修復：識別 ssh_diagnose 模式，路由到 ssh_get_top_processes / ssh_get_disk_usage
         _action_lower = action.lower().strip()
         if _action_lower.startswith("docker restart"):
             _tool = "docker_restart"
@@ -3108,6 +3111,9 @@ class DecisionManager:
         elif _action_lower.startswith("systemctl restart"):
             _tool = "service_restart"
             _service = target
+        elif _action_lower.startswith("ssh ") and ("ps aux" in _action_lower or "top" in _action_lower or "free" in _action_lower or "df -h" in _action_lower or "uptime" in _action_lower):
+            # 主機診斷指令：自動收集 CPU/記憶體/磁碟，不修改任何狀態
+            _tool = "ssh_diagnose"
         else:
             logger.info(
                 "ssh_execute_unknown_action",
@@ -3125,8 +3131,9 @@ class DecisionManager:
         params: dict = {"host": _host}
         if _tool == "docker_restart":
             params["container"] = _container
-        else:
+        elif _tool == "service_restart":
             params["service"] = _service
+        # ssh_diagnose: 只需 host，無額外 params
 
         try:
             result = await self._ssh.execute(tool_name=_tool, parameters=params)
diff --git a/k8s/awoooi-prod/04-configmap.yaml b/k8s/awoooi-prod/04-configmap.yaml
index e96e91a8..981a715a 100644
--- a/k8s/awoooi-prod/04-configmap.yaml
+++ b/k8s/awoooi-prod/04-configmap.yaml
@@ -110,6 +110,10 @@ data:
   # SSH_MCP_ENABLED=true 需確認 ssh-mcp-key Secret 已建立且 188 已加 authorized_keys
   SSH_MCP_ENABLED: "true"
   SSH_MCP_KNOWN_HOSTS_FILE: "/etc/ssh-mcp/known_hosts"
+  # 2026-04-27 Claude Sonnet 4.6: 授權主機告警 SSH 自動執行白名單
+  # 根因：SSH_MCP_ALLOWED_HOSTS 未設定 → _ssh_execute() 攔截 → 主機告警全部降級人工審核
+  # 四台主機：110(DevOps金庫/wooo), 120(K3s-1/wooo), 121(K3s-2/wooo), 188(AI中心/ollama)
+  SSH_MCP_ALLOWED_HOSTS: "192.168.0.110,192.168.0.120,192.168.0.121,192.168.0.188"
   # MCP Phase 3 (2026-04-11 Claude Sonnet 4.6): ArgoCD + Sentry MCP 啟用
   # ARGOCD_API_TOKEN 在 Secrets 中配置
   ARGOCD_MCP_ENABLED: "true"