fix: 修复集群不可达时误报100分的严重bug

- 新增 check_connectivity() 连通性预检: kubectl存在性/kubeconfig/API Server连接
- 连不上集群直接返回0分+明确错误信息+排查建议(不再静默跳过)
- 每个检查项kubectl失败时必须报critical问题(不再忽略error)
- 前端: 连接失败时显示红色错误页+错误详情+排查建议+重新诊断按钮
- 智能识别常见错误: connection refused/证书过期/超时/DNS解析失败等

backend/diagnosis.py

@@ -27,8 +27,8 @@ async def _run_kubectl(args: list[str], timeout: int = 30) -> dict:
         return {"error": str(e), "data": None}
 
 
-async def _run_kubectl_raw(args: list[str], timeout: int = 30) -> str:
+async def _run_kubectl_raw(args: list[str], timeout: int = 30) -> tuple[str, str, int]:
-    """执行 kubectl 命令，返回原始文本"""
+    """执行 kubectl 命令，返回 (stdout, stderr, returncode)"""
     cmd = [KUBECTL] + args
     try:
         proc = await asyncio.create_subprocess_exec(
@@ -37,9 +37,11 @@ async def _run_kubectl_raw(args: list[str], timeout: int = 30) -> str:
             stderr=asyncio.subprocess.PIPE,
         )
         stdout, stderr = await asyncio.wait_for(proc.communicate(), timeout=timeout)
-        return stdout.decode().strip()
+        return stdout.decode().strip(), stderr.decode().strip(), proc.returncode
-    except Exception:
+    except asyncio.TimeoutError:
-        return ""
+        return "", f"命令超时 ({timeout}s)", -1
+    except Exception as e:
+        return "", str(e), -1
 
 
 def _parse_resource_quantity(q: str) -> float:
@@ -61,6 +63,56 @@ def _parse_resource_quantity(q: str) -> float:
         return 0
 
 
+# ─── 连通性检查 (最优先) ──────────────────────────────────
+
+async def check_connectivity() -> dict:
+    """检查 kubectl 是否能连接到集群 API Server"""
+    # 1. 检查 kubectl 是否存在
+    import os
+    if not os.path.isfile(KUBECTL):
+        return {
+            "connected": False,
+            "error": f"kubectl 不存在: {KUBECTL}",
+            "suggestion": "请安装 kubectl 并确保在 PATH 中",
+        }
+
+    # 2. 检查 kubeconfig
+    kubeconfig = os.environ.get("KUBECONFIG", os.path.expanduser("~/.kube/config"))
+    if not os.path.isfile(kubeconfig):
+        return {
+            "connected": False,
+            "error": f"kubeconfig 不存在: {kubeconfig}",
+            "suggestion": "请将集群 kubeconfig 放到 ~/.kube/config 或设置 KUBECONFIG 环境变量",
+        }
+
+    # 3. 尝试连接 API Server
+    stdout, stderr, code = await _run_kubectl_raw(["cluster-info"], timeout=10)
+    if code != 0:
+        # 提取关键错误信息
+        err_msg = stderr or stdout or "未知错误"
+        # 常见错误模式
+        if "connection refused" in err_msg.lower():
+            suggestion = "API Server 连接被拒绝。请检查: 1) kubelet/apiserver 是否运行 (systemctl status kubelet) 2) 证书是否过期 3) 端口 6443 是否监听"
+        elif "no such host" in err_msg.lower() or "dial tcp" in err_msg.lower():
+            suggestion = "无法解析或连接 API Server 地址。请检查 kubeconfig 中的 server 地址是否正确"
+        elif "certificate" in err_msg.lower() or "x509" in err_msg.lower():
+            suggestion = "证书错误。请检查: 1) 集群证书是否过期 (kubeadm certs check-expiration) 2) 系统时间是否正确"
+        elif "timeout" in err_msg.lower() or "timed out" in err_msg.lower():
+            suggestion = "连接超时。请检查: 1) 网络是否可达 2) 防火墙是否放行 6443 端口 3) API Server 是否运行"
+        elif "unable to connect" in err_msg.lower() or "could not" in err_msg.lower():
+            suggestion = "无法连接到集群。请检查: 1) systemctl status kubelet 2) journalctl -u kubelet --no-pager -n 50 3) crictl ps 查看容器状态"
+        else:
+            suggestion = "请检查 kubelet 和 API Server 状态: systemctl status kubelet && journalctl -u kubelet -n 50"
+
+        return {
+            "connected": False,
+            "error": err_msg[:500],
+            "suggestion": suggestion,
+        }
+
+    return {"connected": True, "error": None, "info": stdout}
+
+
 # ─── 诊断项 ───────────────────────────────────────────────
 
 async def check_cluster_info() -> dict:
@@ -68,9 +120,15 @@ async def check_cluster_info() -> dict:
     ver = await _run_kubectl(["version"])
     nodes = await _run_kubectl(["get", "nodes"])
     namespaces = await _run_kubectl(["get", "namespaces"])
+
+    issues = []
+    if ver.get("error"):
+        issues.append({"level": "critical", "resource": "cluster", "message": f"无法获取集群版本: {ver['error'][:200]}"})
+
     return {
         "name": "cluster_info",
         "title": "集群信息",
+        "issues": issues,
         "version": ver,
         "nodes": nodes,
         "namespaces": namespaces,
@@ -85,20 +143,23 @@ async def check_pods(namespace: str = "") -> dict:
     else:
         args += ["--all-namespaces"]
     result = await _run_kubectl(args)
-    
+
     issues = []
     pods_summary = {"total": 0, "running": 0, "pending": 0, "failed": 0, "unknown": 0, "crashloop": 0}
-    
+
+    if result.get("error"):
+        issues.append({"level": "critical", "resource": "pods", "message": f"无法获取 Pod 列表: {result['error'][:200]}"})
+        return {"name": "pods", "title": "Pod 状态检查", "summary": pods_summary, "issues": issues, "raw": result}
+
     if result["data"] and "items" in result["data"]:
         for pod in result["data"]["items"]:
             pods_summary["total"] += 1
             phase = pod.get("status", {}).get("phase", "Unknown")
             name = pod["metadata"]["name"]
             ns = pod["metadata"].get("namespace", "default")
-            
+
             if phase == "Running":
                 pods_summary["running"] += 1
-                # 检查重启次数
                 for cs in pod.get("status", {}).get("containerStatuses", []):
                     restarts = cs.get("restartCount", 0)
                     if restarts > 5:
@@ -125,7 +186,7 @@ async def check_pods(namespace: str = "") -> dict:
                 issues.append({"level": "critical", "resource": f"{ns}/{name}", "message": "Pod 处于 Failed 状态"})
             else:
                 pods_summary["unknown"] += 1
-    
+
     return {
         "name": "pods",
         "title": "Pod 状态检查",
@@ -140,7 +201,11 @@ async def check_nodes() -> dict:
     result = await _run_kubectl(["get", "nodes"])
     issues = []
     nodes_summary = {"total": 0, "ready": 0, "not_ready": 0}
-    
+
+    if result.get("error"):
+        issues.append({"level": "critical", "resource": "nodes", "message": f"无法获取 Node 列表: {result['error'][:200]}"})
+        return {"name": "nodes", "title": "Node 状态检查", "summary": nodes_summary, "issues": issues, "raw": result}
+
     if result["data"] and "items" in result["data"]:
         for node in result["data"]["items"]:
             nodes_summary["total"] += 1
@@ -161,8 +226,7 @@ async def check_nodes() -> dict:
             else:
                 nodes_summary["not_ready"] += 1
                 issues.append({"level": "critical", "resource": name, "message": "节点 NotReady"})
-            
+
-            # 资源使用
             alloc = node.get("status", {}).get("allocatable", {})
             cap = node.get("status", {}).get("capacity", {})
             if alloc and cap:
@@ -175,7 +239,7 @@ async def check_nodes() -> dict:
                             "resource": name,
                             "message": f"节点 {res} 可分配量不足 10%",
                         })
-    
+
     return {
         "name": "nodes",
         "title": "Node 状态检查",
@@ -193,11 +257,16 @@ async def check_events(namespace: str = "") -> dict:
     else:
         args += ["--all-namespaces"]
     result = await _run_kubectl(args)
-    
+
     issues = []
     events_list = []
+
+    if result.get("error"):
+        issues.append({"level": "critical", "resource": "events", "message": f"无法获取事件: {result['error'][:200]}"})
+        return {"name": "events", "title": "异常事件检查", "warning_count": 0, "events": [], "issues": issues, "raw": result}
+
     if result["data"] and "items" in result["data"]:
-        for ev in result["data"]["items"][-50:]:  # 最近50条
+        for ev in result["data"]["items"][-50:]:
             events_list.append({
                 "namespace": ev["metadata"].get("namespace", ""),
                 "reason": ev.get("reason", ""),
@@ -213,11 +282,11 @@ async def check_events(namespace: str = "") -> dict:
                     "resource": f"{ev['metadata'].get('namespace', '')}/{ev.get('involvedObject', {}).get('name', '')}",
                     "message": f"[{ev.get('reason', '')}] {ev.get('message', '')[:200]}",
                 })
-    
+
     return {
         "name": "events",
         "title": "异常事件检查",
-        "warning_count": len(issues),
+        "warning_count": len([i for i in issues if i["level"] == "warning"]),
         "events": events_list,
         "issues": issues,
         "raw": result,
@@ -232,9 +301,14 @@ async def check_deployments(namespace: str = "") -> dict:
     else:
         args += ["--all-namespaces"]
     result = await _run_kubectl(args)
-    
+
     issues = []
     deploys = []
+
+    if result.get("error"):
+        issues.append({"level": "critical", "resource": "deployments", "message": f"无法获取 Deployment: {result['error'][:200]}"})
+        return {"name": "deployments", "title": "Deployment 状态检查", "deployments": [], "issues": issues, "raw": result}
+
     if result["data"] and "items" in result["data"]:
         for dep in result["data"]["items"]:
             name = dep["metadata"]["name"]
@@ -244,7 +318,7 @@ async def check_deployments(namespace: str = "") -> dict:
             ready = status.get("readyReplicas", 0) or 0
             available = status.get("availableReplicas", 0) or 0
             updated = status.get("updatedReplicas", 0) or 0
-            
+
             deploys.append({
                 "namespace": ns, "name": name,
                 "desired": spec_replicas, "ready": ready,
@@ -262,7 +336,7 @@ async def check_deployments(namespace: str = "") -> dict:
                     "resource": f"{ns}/{name}",
                     "message": f"滚动更新未完成: 已更新 {updated}/{spec_replicas}",
                 })
-    
+
     return {
         "name": "deployments",
         "title": "Deployment 状态检查",
@@ -280,8 +354,13 @@ async def check_services(namespace: str = "") -> dict:
     else:
         args += ["--all-namespaces"]
     result = await _run_kubectl(args)
-    
+
     issues = []
+
+    if result.get("error"):
+        issues.append({"level": "critical", "resource": "services", "message": f"无法获取 Endpoint: {result['error'][:200]}"})
+        return {"name": "services", "title": "Service/Endpoint 检查", "issues": issues, "raw": result}
+
     if result["data"] and "items" in result["data"]:
         for ep in result["data"]["items"]:
             name = ep["metadata"]["name"]
@@ -294,7 +373,7 @@ async def check_services(namespace: str = "") -> dict:
                     "resource": f"{ns}/{name}",
                     "message": "Service 没有可用的后端 Endpoint",
                 })
-    
+
     return {
         "name": "services",
         "title": "Service/Endpoint 检查",
@@ -311,8 +390,13 @@ async def check_pvc(namespace: str = "") -> dict:
     else:
         args += ["--all-namespaces"]
     result = await _run_kubectl(args)
-    
+
     issues = []
+
+    if result.get("error"):
+        issues.append({"level": "critical", "resource": "pvc", "message": f"无法获取 PVC: {result['error'][:200]}"})
+        return {"name": "pvc", "title": "PVC 存储检查", "issues": issues, "raw": result}
+
     if result["data"] and "items" in result["data"]:
         for pvc in result["data"]["items"]:
             name = pvc["metadata"]["name"]
@@ -324,7 +408,7 @@ async def check_pvc(namespace: str = "") -> dict:
                     "resource": f"{ns}/{name}",
                     "message": f"PVC 状态异常: {phase}",
                 })
-    
+
     return {
         "name": "pvc",
         "title": "PVC 存储检查",
@@ -335,12 +419,23 @@ async def check_pvc(namespace: str = "") -> dict:
 
 async def check_resource_usage() -> dict:
     """节点资源使用率 (需要 metrics-server)"""
-    raw = await _run_kubectl_raw(["top", "nodes", "--no-headers"])
+    stdout, stderr, code = await _run_kubectl_raw(["top", "nodes", "--no-headers"])
     issues = []
     nodes_usage = []
-    
+
-    if raw and "error" not in raw.lower():
+    if code != 0:
-        for line in raw.strip().split("\n"):
+        # metrics-server 不可用不算 critical，只是跳过
+        return {
+            "name": "resource_usage",
+            "title": "资源使用率",
+            "issues": [],
+            "nodes": [],
+            "note": f"metrics-server 不可用: {(stderr or stdout)[:200]}",
+            "raw": {"error": stderr or stdout},
+        }
+
+    if stdout:
+        for line in stdout.strip().split("\n"):
             parts = line.split()
             if len(parts) >= 5:
                 name = parts[0]
@@ -359,22 +454,13 @@ async def check_resource_usage() -> dict:
                         issues.append({"level": "warning", "resource": name, "message": f"内存使用率 {mem_v}%"})
                 except ValueError:
                     pass
-    else:
+
-        return {
-            "name": "resource_usage",
-            "title": "资源使用率",
-            "issues": [],
-            "nodes": [],
-            "note": "metrics-server 不可用，跳过资源使用率检查",
-            "raw": {"error": raw},
-        }
-    
     return {
         "name": "resource_usage",
         "title": "资源使用率",
         "issues": issues,
         "nodes": nodes_usage,
-        "raw": {"text": raw},
+        "raw": {"text": stdout},
     }
 
 
@@ -386,12 +472,18 @@ async def check_network_policies(namespace: str = "") -> dict:
     else:
         args += ["--all-namespaces"]
     result = await _run_kubectl(args)
+
+    issues = []
+    if result.get("error"):
+        issues.append({"level": "warning", "resource": "network", "message": f"无法获取网络策略: {result['error'][:200]}"})
+        return {"name": "network", "title": "网络策略检查", "policy_count": 0, "issues": issues, "raw": result}
+
     count = len(result["data"].get("items", [])) if result["data"] else 0
     return {
         "name": "network",
         "title": "网络策略检查",
         "policy_count": count,
-        "issues": [],
+        "issues": issues,
         "raw": result,
     }
 
@@ -414,7 +506,31 @@ ALL_CHECKS = {
 async def run_full_diagnosis(namespace: str = "", checks: Optional[list[str]] = None) -> dict:
     """执行完整诊断"""
     start = datetime.now()
-    
+
+    # ★ 第一步: 连通性检查
+    conn = await check_connectivity()
+    if not conn["connected"]:
+        return {
+            "timestamp": start.isoformat(),
+            "elapsed_seconds": round((datetime.now() - start).total_seconds(), 2),
+            "namespace": namespace or "all",
+            "score": 0,
+            "status": "critical",
+            "connected": False,
+            "connectivity_error": conn["error"],
+            "connectivity_suggestion": conn.get("suggestion", ""),
+            "critical_count": 1,
+            "warning_count": 0,
+            "issues": [{
+                "level": "critical",
+                "check": "集群连通性",
+                "resource": "API Server",
+                "message": f"无法连接到集群: {conn['error'][:300]}",
+            }],
+            "checks": {},
+        }
+
+    # ★ 第二步: 执行各项检查
     selected = checks or list(ALL_CHECKS.keys())
     tasks = {}
     for name in selected:
@@ -424,45 +540,49 @@ async def run_full_diagnosis(namespace: str = "", checks: Optional[list[str]] =
                 tasks[name] = fn(namespace)
             else:
                 tasks[name] = fn()
-    
+
     results = {}
     for name, coro in tasks.items():
         try:
             results[name] = await coro
         except Exception as e:
-            results[name] = {"name": name, "title": name, "error": str(e), "issues": []}
+            results[name] = {
-    
+                "name": name, "title": name, "error": str(e),
+                "issues": [{"level": "critical", "resource": name, "message": f"检查执行异常: {str(e)}"}],
+            }
+
     # 汇总
     all_issues = []
     for r in results.values():
         for issue in r.get("issues", []):
             issue["check"] = r.get("title", r.get("name", ""))
             all_issues.append(issue)
-    
+
     critical = [i for i in all_issues if i["level"] == "critical"]
     warning = [i for i in all_issues if i["level"] == "warning"]
-    
+
     elapsed = (datetime.now() - start).total_seconds()
-    
+
     # 健康评分 (100 分制)
     score = 100
     score -= len(critical) * 15
     score -= len(warning) * 5
     score = max(0, score)
-    
+
     if score >= 90:
         status = "healthy"
     elif score >= 60:
         status = "warning"
     else:
         status = "critical"
-    
+
     return {
         "timestamp": start.isoformat(),
         "elapsed_seconds": round(elapsed, 2),
         "namespace": namespace or "all",
         "score": score,
         "status": status,
+        "connected": True,
         "critical_count": len(critical),
         "warning_count": len(warning),
         "issues": all_issues,
@@ -479,45 +599,53 @@ def build_diagnosis_report(diagnosis: dict) -> str:
     lines.append(f"健康评分: {diagnosis['score']}/100 ({diagnosis['status']})")
     lines.append(f"严重问题: {diagnosis['critical_count']} 个, 警告: {diagnosis['warning_count']} 个")
     lines.append("")
-    
+
+    # 连通性失败
+    if not diagnosis.get("connected", True):
+        lines.append("## ⚠️ 集群连接失败")
+        lines.append(f"错误: {diagnosis.get('connectivity_error', '未知')}")
+        lines.append(f"建议: {diagnosis.get('connectivity_suggestion', '')}")
+        lines.append("")
+        return "\n".join(lines)
+
     if diagnosis["issues"]:
         lines.append("## 发现的问题")
         for i, issue in enumerate(diagnosis["issues"], 1):
             icon = "🔴" if issue["level"] == "critical" else "🟡"
             lines.append(f"{i}. {icon} [{issue['check']}] {issue['resource']}: {issue['message']}")
         lines.append("")
-    
+
     # Pod 摘要
     pods = diagnosis["checks"].get("pods", {})
     if pods.get("summary"):
         s = pods["summary"]
         lines.append(f"## Pod 状态: 总计 {s['total']}, Running {s['running']}, Pending {s['pending']}, Failed {s['failed']}, CrashLoop {s.get('crashloop', 0)}")
-    
+
     # Node 摘要
     nodes = diagnosis["checks"].get("nodes", {})
     if nodes.get("summary"):
         s = nodes["summary"]
         lines.append(f"## Node 状态: 总计 {s['total']}, Ready {s['ready']}, NotReady {s['not_ready']}")
-    
+
     # Deployment 摘要
     deps = diagnosis["checks"].get("deployments", {})
     if deps.get("deployments"):
         lines.append("## Deployment 状态:")
         for d in deps["deployments"]:
             lines.append(f"  - {d['namespace']}/{d['name']}: {d['ready']}/{d['desired']} ready")
-    
+
     # 异常事件
     events = diagnosis["checks"].get("events", {})
     if events.get("events"):
         lines.append(f"\n## 最近异常事件 (共 {len(events['events'])} 条):")
         for ev in events["events"][-20:]:
             lines.append(f"  - [{ev['type']}] {ev['object']}: {ev['reason']} - {ev['message'][:150]}")
-    
+
     # 资源使用
     usage = diagnosis["checks"].get("resource_usage", {})
     if usage.get("nodes"):
         lines.append("\n## 节点资源使用:")
         for n in usage["nodes"]:
             lines.append(f"  - {n['name']}: CPU {n['cpu_pct']}%, 内存 {n['mem_pct']}%")
-    
+
     return "\n".join(lines)

backend/main.py

@@ -13,6 +13,7 @@ from typing import Optional
 from backend.config import PORT
 from backend.diagnosis import (
     run_full_diagnosis, build_diagnosis_report, ALL_CHECKS,
+    check_connectivity,
     check_cluster_info, check_pods, check_nodes, check_events,
     check_deployments, check_services, check_pvc, check_resource_usage,
     check_network_policies,
@@ -82,12 +83,46 @@ async def diagnose_stream(namespace: str = ""):
 
     async def event_generator():
         start = datetime.now()
+
+        # ★ 第一步: 连通性检查
+        yield f"data: {json.dumps({'type': 'progress', 'step': 0, 'total': len(CHECK_ORDER) + 1, 'name': 'connectivity', 'title': '集群连通性检查', 'status': 'running'}, ensure_ascii=False)}\n\n"
+
+        conn = await check_connectivity()
+        if not conn["connected"]:
+            yield f"data: {json.dumps({'type': 'progress', 'step': 0, 'total': len(CHECK_ORDER) + 1, 'name': 'connectivity', 'title': '集群连通性检查', 'status': 'done', 'issues': 1}, ensure_ascii=False)}\n\n"
+
+            diagnosis = {
+                "timestamp": start.isoformat(),
+                "elapsed_seconds": round((datetime.now() - start).total_seconds(), 2),
+                "namespace": namespace or "all",
+                "score": 0,
+                "status": "critical",
+                "connected": False,
+                "connectivity_error": conn["error"],
+                "connectivity_suggestion": conn.get("suggestion", ""),
+                "critical_count": 1,
+                "warning_count": 0,
+                "issues": [{
+                    "level": "critical",
+                    "check": "集群连通性",
+                    "resource": "API Server",
+                    "message": f"无法连接到集群: {conn['error'][:300]}",
+                }],
+                "checks": {},
+            }
+            _last_diagnosis = diagnosis
+            _last_report = build_diagnosis_report(diagnosis)
+            yield f"data: {json.dumps({'type': 'complete', 'diagnosis': diagnosis}, ensure_ascii=False)}\n\n"
+            return
+
+        yield f"data: {json.dumps({'type': 'progress', 'step': 0, 'total': len(CHECK_ORDER) + 1, 'name': 'connectivity', 'title': '集群连通性检查', 'status': 'done', 'issues': 0}, ensure_ascii=False)}\n\n"
+
+        # ★ 第二步: 执行各项检查
         results = {}
         all_issues = []
-        total = len(CHECK_ORDER)
+        total = len(CHECK_ORDER) + 1
 
         for idx, (name, title, fn) in enumerate(CHECK_ORDER, 1):
-            # 推送: 开始检查
             yield f"data: {json.dumps({'type': 'progress', 'step': idx, 'total': total, 'name': name, 'title': title, 'status': 'running'}, ensure_ascii=False)}\n\n"
 
             try:
@@ -101,10 +136,13 @@ async def diagnose_stream(namespace: str = ""):
                     issue["check"] = title
                     all_issues.append(issue)
             except Exception as e:
-                results[name] = {"name": name, "title": title, "error": str(e), "issues": []}
+                results[name] = {
-                issue_count = -1
+                    "name": name, "title": title, "error": str(e),
+                    "issues": [{"level": "critical", "resource": name, "message": f"检查执行异常: {str(e)}"}],
+                }
+                issue_count = 1
+                all_issues.append({"level": "critical", "check": title, "resource": name, "message": f"检查执行异常: {str(e)}"})
 
-            # 推送: 完成检查
             yield f"data: {json.dumps({'type': 'progress', 'step': idx, 'total': total, 'name': name, 'title': title, 'status': 'done', 'issues': issue_count}, ensure_ascii=False)}\n\n"
 
         # 汇总
@@ -120,6 +158,7 @@ async def diagnose_stream(namespace: str = ""):
             "namespace": namespace or "all",
             "score": score,
             "status": status,
+            "connected": True,
             "critical_count": len(critical),
             "warning_count": len(warning),
             "issues": all_issues,
@@ -129,7 +168,6 @@ async def diagnose_stream(namespace: str = ""):
         _last_diagnosis = diagnosis
         _last_report = build_diagnosis_report(diagnosis)
 
-        # 推送: 最终结果
         yield f"data: {json.dumps({'type': 'complete', 'diagnosis': diagnosis}, ensure_ascii=False)}\n\n"
 
     return StreamingResponse(

frontend/src/App.vue

@@ -58,8 +58,31 @@
         </el-card>
       </div>
 
+      <!-- 集群连接失败 -->
+      <div v-if="diagnosis && !diagnosing && diagnosis.connected === false" class="conn-error-box">
+        <el-card shadow="never" class="conn-error-card">
+          <div class="conn-error-icon">
+            <el-icon :size="64" color="#f56c6c"><CircleCloseFilled /></el-icon>
+          </div>
+          <h2>无法连接到 Kubernetes 集群</h2>
+          <div class="conn-error-detail">
+            <el-alert type="error" :closable="false" show-icon>
+              <template #title>错误信息</template>
+              <pre class="conn-error-pre">{{ diagnosis.connectivity_error }}</pre>
+            </el-alert>
+            <el-alert v-if="diagnosis.connectivity_suggestion" type="warning" :closable="false" show-icon style="margin-top: 12px">
+              <template #title>排查建议</template>
+              <div>{{ diagnosis.connectivity_suggestion }}</div>
+            </el-alert>
+          </div>
+          <div class="conn-error-actions">
+            <el-button type="primary" @click="runDiagnosis" :icon="Refresh">重新诊断</el-button>
+          </div>
+        </el-card>
+      </div>
+
       <!-- 诊断结果 -->
-      <template v-if="diagnosis && !diagnosing">
+      <template v-if="diagnosis && !diagnosing && diagnosis.connected !== false">
         <!-- 概览卡片 -->
         <el-row :gutter="16" class="summary-row">
           <el-col :span="4">
@@ -219,7 +242,7 @@
 <script setup>
 import { ref, computed, nextTick } from 'vue'
 import { marked } from 'marked'
-import { Refresh, MagicStick, Loading, WarningFilled, Warning, Promotion, Monitor, CircleCheckFilled, CircleClose } from '@element-plus/icons-vue'
+import { Refresh, MagicStick, Loading, WarningFilled, Warning, Promotion, Monitor, CircleCheckFilled, CircleClose, CircleCloseFilled } from '@element-plus/icons-vue'
 import { ElMessage } from 'element-plus'
 
 const API = '/api'
@@ -405,6 +428,15 @@ body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC'
 /* 诊断进度 */
 .progress-box { display: flex; justify-content: center; padding-top: 40px; }
 .progress-card { width: 600px; }
+
+/* 连接失败 */
+.conn-error-box { display: flex; justify-content: center; padding-top: 40px; }
+.conn-error-card { width: 700px; text-align: center; padding: 20px 0; }
+.conn-error-icon { margin-bottom: 16px; }
+.conn-error-card h2 { font-size: 22px; color: #303133; margin-bottom: 20px; }
+.conn-error-detail { text-align: left; margin: 0 20px; }
+.conn-error-pre { white-space: pre-wrap; word-break: break-all; font-size: 13px; margin: 8px 0 0; color: #f56c6c; }
+.conn-error-actions { margin-top: 24px; }
 .progress-steps { display: flex; flex-direction: column; gap: 4px; }
 .progress-item {
   display: flex; align-items: center; gap: 10px;