feat: 模型健康/熔断态 surface 到管理端（T4.F 可观测）

failover/熔断的运行时态原来只在 dispatcher 日志、admin 看不到 —— 本次接到概览可见：
- harness: CircuitBreaker.Snapshot() 只读观测访问器（state + fails，不动状态机）
- llm: Pool.ModelHealth() 上报主备链每模型 {provider,model,role,state,fails}；
  buildWithFallbacks 把模型名↔breaker 配对（同包直接读 failoverModel.breakers）；
  newFailoverModel 改返回具体类型以便读 breakers
- dispatcher 心跳 payload 加 models[]
- gateway /admin/overview 独立超时 Ping dispatcher，合并进 models.health
- admin 概览「模型路由」新增「运行时链路态(实时)」：逐模型状态点
  (🟢在线/🔴熔断中+失败数/🟡半开探测/单点)
- 单测：Snapshot、Pool.ModelHealth(名字↔态配对/单点/空)
- live：配坏主→提交任务打熔断→概览显示 broken-demo「熔断中·失败3」，备用在线

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

sundynix-admin/src/api.ts

@@ -219,6 +219,15 @@ export async function statsOverview(): Promise<Overview> {
 
 // —— 管理端系统级聚合（控制塔口径，RequireAdmin）——
 // 区别于 statsOverview（桌面端个人工作台）：这里一律全平台口径——全部用户/任务/评测/模型态/提示词态/健康。
+// 单模型运行时健康态（failover 链上主/备各一条）。
+export interface ModelHealthItem {
+  provider: string;
+  model: string;
+  role: string; // primary / fallback
+  state: string; // closed(在线) / open(熔断中) / half-open(半开探测) / single(无备用链)
+  fails: number;
+}
+
 export interface AdminOverview {
   users: number;
   kb_count: number; // 全平台知识库数
@@ -230,7 +239,14 @@ export interface AdminOverview {
   eval_avg: number;
   faithful_avg: number;
   eval_count: number;
-  models: { chat_count: number; embedding_count: number; active_chat: string; active_embedding: string; fallbacks: number };
+  models: {
+    chat_count: number;
+    embedding_count: number;
+    active_chat: string;
+    active_embedding: string;
+    fallbacks: number;
+    health: ModelHealthItem[]; // 运行时每模型 failover/熔断态（来自 dispatcher）
+  };
   prompts: { managed: number; overrides: number };
   services: Record<string, boolean>;
   checked_at: string;

sundynix-admin/src/pages/DashboardPage.tsx

@@ -14,6 +14,15 @@ const STATUS_STYLE: Record<string, { label: string; color: string }> = {
 };
 const statusStyle = (s: string) => STATUS_STYLE[s] ?? { label: s, color: "#94a3b8" };
 
+// 模型熔断态 → 展示样式。
+const BREAKER_STYLE: Record<string, { label: string; dot: string; text: string }> = {
+  closed: { label: "在线", dot: "bg-emerald-500", text: "text-emerald-600" },
+  open: { label: "熔断中", dot: "bg-rose-500", text: "text-rose-500" },
+  "half-open": { label: "半开探测", dot: "bg-amber-500", text: "text-amber-600" },
+  single: { label: "单点", dot: "bg-gray-300", text: "text-gray-400" },
+};
+const breakerStyle = (s: string) => BREAKER_STYLE[s] ?? { label: s, dot: "bg-gray-300", text: "text-gray-400" };
+
 function last7DaysTrend(trend: { key: string; count: number }[]): { key: string; count: number }[] {
   const byKey = new Map(trend.map((d) => [d.key, d.count]));
   const out: { key: string; count: number }[] = [];
@@ -169,6 +178,27 @@ export function DashboardPage() {
               <span className="text-gray-500">chat {m.chat_count} · embedding {m.embedding_count}</span>
             </Row>
           </div>
+
+          {/* 运行时 failover/熔断态（来自 dispatcher） */}
+          {m.health && m.health.length > 0 && (
+            <div className="mt-3 border-t border-gray-50 pt-3">
+              <div className="mb-2 text-[10px] font-semibold uppercase tracking-wider text-gray-300">运行时链路态（实时）</div>
+              <div className="space-y-1.5">
+                {m.health.map((h, i) => {
+                  const st = breakerStyle(h.state);
+                  return (
+                    <div key={`${h.model}-${i}`} className="flex items-center gap-2 text-xs">
+                      <span className={`h-2 w-2 shrink-0 rounded-full ${st.dot}`} title={st.label} />
+                      <span className="rounded bg-gray-50 px-1.5 text-[10px] text-gray-400">{h.role === "primary" ? "主" : "备"}</span>
+                      <code className="min-w-0 flex-1 truncate text-[11px] text-gray-600">{h.model}</code>
+                      <span className={`shrink-0 text-[10px] ${st.text}`}>{st.label}</span>
+                      {h.fails > 0 && h.state !== "closed" && <span className="shrink-0 text-[10px] text-gray-300">失败 {h.fails}</span>}
+                    </div>
+                  );
+                })}
+              </div>
+            </div>
+          )}
         </div>
 
         <div className="rounded-xl border border-gray-100 bg-white p-5 shadow-sm">