中控总览改为后台常驻并行拉取热缓存，浏览器只读缓存并经 SSE 更新。

Co-authored-by: Cursor <cursoragent@cursor.com>

static/hub.js

@@ -581,7 +581,7 @@
         if (dd.submitted_sheets != null) msg += " · " + dd.submitted_sheets + " 张";
         if (dd.fully_closed) msg += " · 已全平";
         alert(msg);
-        await refresh();
+        await requestOverviewRefresh();
       } else {
         alert((dd && dd.msg) || "平仓失败");
         btn.disabled = false;
@@ -759,21 +759,34 @@
     return best;
   }
 
-  async function refresh() {
+  let overviewVersion = 0;
+  let overviewLoading = false;
+  let overviewEventSource = null;
+  let overviewReconnectTimer = null;
+
+  async function refresh(opts) {
+    opts = opts || {};
+    const silent = !!opts.silent;
     const status = document.getElementById("overview-status");
     const grid = document.getElementById("overview-grid");
     if (!grid) return;
-    if (status) status.textContent = "刷新中…";
+    if (overviewLoading) return;
+    overviewLoading = true;
+    if (status && !silent) status.textContent = "读取缓存…";
     try {
-      const r = await fetch("/api/overview");
+      // 只读中控热缓存;后台常驻并行 pull,不在此请求内打实例
+      const r = await fetch("/api/overview", { credentials: "same-origin" });
       const d = await r.json();
-      if (!d.ok) throw new Error(d.msg || "失败");
+      if (!d.ok) throw new Error(d.msg || d.error || "失败");
+      overviewVersion = Number(d.overview_version) || overviewVersion;
       const list = sortInstancesByMode(d.instances || []);
       renderOverviewSummary(list);
       if (global.HubQuotes && HubQuotes.paint) HubQuotes.paint(list);
       if (!list.length) {
         grid.innerHTML =
-          '<p class="muted">暂无启用实例,请先到「实例」添加.</p>';
+          d.pulling || !d.updated_at
+            ? '<p class="muted">后台首次拉取中…</p>'
+            : '<p class="muted">暂无启用实例,请先到「实例」添加.</p>';
       } else if (isHubPhone()) {
         grid.innerHTML =
           '<div class="hub-phone-cards">' + list.map(renderPhoneCard).join("") + "</div>";
@@ -790,15 +803,20 @@
       }
       if (status) {
         const s = summarizeOverview(list);
-        const pulled = latestPulledAt(list);
+        const pulled = latestPulledAt(list) || d.updated_at || "";
+        const sec = Number(d.poll_interval_sec) || 10;
+        const live = overviewEventSource && overviewEventSource.readyState === 1;
         status.textContent =
-          "已更新 · 共 " +
+          (live ? "SSE 已连接 · " : "") +
+          "缓存 " +
           list.length +
           " 台 · 在线 " +
           s.all.online +
           " · 离线 " +
           s.all.offline +
-          (pulled ? " · 拉取时间 " + pulled : "");
+          (pulled ? " · " + pulled : "") +
+          (d.pulling ? " · 后台拉取中" : " · 后台每 " + sec + "s 并行拉") +
+          (d.error ? " · " + d.error : "");
       }
     } catch (e) {
       if (status) status.textContent = e.message || "加载失败";
@@ -808,9 +826,60 @@
         box.innerHTML = "";
       }
       if (global.HubQuotes && HubQuotes.paint) HubQuotes.paint([]);
+    } finally {
+      overviewLoading = false;
     }
   }
 
+  function closeOverviewStream() {
+    if (overviewEventSource) {
+      overviewEventSource.close();
+      overviewEventSource = null;
+    }
+    if (overviewReconnectTimer) {
+      clearTimeout(overviewReconnectTimer);
+      overviewReconnectTimer = null;
+    }
+  }
+
+  function connectOverviewStream() {
+    const grid = document.getElementById("overview-grid");
+    if (!grid || typeof EventSource === "undefined") return;
+    closeOverviewStream();
+    overviewEventSource = new EventSource("/api/overview/stream");
+    overviewEventSource.addEventListener("overview", function (ev) {
+      try {
+        const st = JSON.parse(ev.data || "{}");
+        const ver = Number(st.overview_version) || 0;
+        if (ver && ver !== overviewVersion) {
+          refresh({ silent: true });
+        } else if (st.pulling) {
+          const status = document.getElementById("overview-status");
+          if (status) status.textContent = "后台并行拉取中…";
+        }
+      } catch (_) {}
+    });
+    overviewEventSource.onerror = function () {
+      closeOverviewStream();
+      const status = document.getElementById("overview-status");
+      if (status) status.textContent = "SSE 断开,8s 后重连…";
+      overviewReconnectTimer = setTimeout(function () {
+        connectOverviewStream();
+        refresh({ silent: true });
+      }, 8000);
+    };
+  }
+
+  async function requestOverviewRefresh() {
+    try {
+      await fetch("/api/overview/refresh", {
+        method: "POST",
+        credentials: "same-origin",
+      });
+    } catch (_) {}
+    refresh({ silent: true });
+  }
+
   const WEEKDAYS = ["周日", "周一", "周二", "周三", "周四", "周五", "周六"];
   const LUNAR_MONTHS = ["正", "二", "三", "四", "五", "六", "七", "八", "九", "十", "冬", "腊"];
   const LUNAR_INFO = [
@@ -1001,12 +1070,19 @@
 
   function boot() {
     const btn = document.getElementById("btn-refresh");
-    if (btn) btn.addEventListener("click", refresh);
+    if (btn) btn.addEventListener("click", function () {
+      requestOverviewRefresh();
+    });
     tickBeijingClock();
     setInterval(tickBeijingClock, 1000);
+    // 先进缓存秒开,再挂 SSE;不再前端定时现场拉实例
     refresh();
-    setInterval(refresh, 10000);
+    connectOverviewStream();
   }
 
-  global.HubOverview = { boot: boot, refresh: refresh };
+  global.HubOverview = {
+    boot: boot,
+    refresh: refresh,
+    requestRefresh: requestOverviewRefresh,
+  };
 })(window);