feat: 实现设备注册和精准控制功能，支持双屏管理；更新相关逻辑以优化设备状态跟踪

backend/static/admin.js

@@ -10,8 +10,46 @@
   var fullscreen = !!init.fullscreen;
   var autostart = !!init.autostart;
 
-  /* 目标屏（双屏独立控制）：both | main | secondary */
-  var screenTarget = 'both';
+  /* 目标屏幕（按 MQTT 客户端精准控制）：client_id + role */
+  var screenId = '';
+  var screenRole = '';
+
+  function applyScreenTarget(sel) {
+    sel = sel || document.getElementById('screenTarget');
+    if (!sel) return;
+    var v = sel.value || '';
+    screenId = v;
+    var opt = null;
+    if (v) { for (var i = 0; i < sel.options.length; i++) { if (sel.options[i].value === v) { opt = sel.options[i]; break; } } }
+    screenRole = opt ? (opt.getAttribute('data-role') || '') : '';
+  }
+
+  function loadScreens() {
+    fetch('/api/display/state', { cache: 'no-store' })
+      .then(function (r) { return r.json(); })
+      .then(function (d) {
+        var sel = document.getElementById('screenTarget');
+        var cnt = document.getElementById('screenCount');
+        if (!sel) return;
+        var devices = (d && d.devices) || [];
+        if (cnt) cnt.textContent = '在线设备：' + (devices.length || 0) + ' 台';
+        var cur = sel.value;
+        sel.innerHTML = '<option value="">全部屏幕</option>';
+        devices.forEach(function (dev) {
+          var role = dev.role || '';
+          var name = role === 'main' ? '主屏' : role === 'secondary' ? '副屏' : (role || '屏幕');
+          var parent = (dev.role === 'secondary' && dev.parent_id) ? '·属于:' + String(dev.parent_id).slice(0, 8) : '';
+          var opt = document.createElement('option');
+          opt.value = dev.device_id;
+          opt.setAttribute('data-role', role);
+          opt.textContent = name + parent + ' · ' + String(dev.device_id).slice(0, 16);
+          sel.appendChild(opt);
+        });
+        if (cur) sel.value = cur;
+        applyScreenTarget(sel);
+      })
+      .catch(function () {});
+  }
 
   /* ---------- Toast ---------- */
   var toastContainer = document.getElementById('toastContainer');
@@ -82,6 +120,7 @@
         setConn('api', true, '在线');
         setConn('mqtt', !!d.mqtt_connected, d.mqtt_connected ? '已连接（' + (d.mqtt_host || '') + '）' : '未连接');
         setConn('screens', (d.screens_online || 0) > 0, (d.screens_online || 0) + ' 台');
+        loadScreens();   // 刷新目标屏幕下拉（按 MQTT 客户端）
         var lc = d.last_command;
         if (lc) {
           var names = { navigate: '页面切换', play: '播放', pause: '暂停', next: '下一项', prev: '上一项',
@@ -98,6 +137,12 @@
       });
   }
   if (connEls.api) { pollStatus(); setInterval(pollStatus, 3000); }
+  // 目标屏幕下拉：变更时记录目标 client_id + role；初始加载一次
+  var screenSel = document.getElementById('screenTarget');
+  if (screenSel) {
+    screenSel.addEventListener('change', function () { applyScreenTarget(screenSel); });
+    loadScreens();
+  }
 
   /* =========================================================
      事件委托：页面切换 / 播放控制 / 媒体操作
@@ -110,19 +155,10 @@
   });
 
   document.addEventListener('click', function (e) {
-    var btn = e.target.closest ? e.target.closest('[data-nav], [data-mqtt], [data-control], [data-action], .copy-btn, [data-preview], .screen-target, #mqttAiSend, #mqttAlertSend') : null;
+    var btn = e.target.closest ? e.target.closest('[data-nav], [data-mqtt], [data-control], [data-action], .copy-btn, [data-preview], #mqttAiSend, #mqttAlertSend') : null;
     if (!btn) return;
     e.stopPropagation();
 
-    // 目标屏选择（双屏独立控制）
-    if (btn.classList.contains('screen-target')) {
-      screenTarget = btn.getAttribute('data-screen') || 'both';
-      var btns = document.querySelectorAll('.screen-target');
-      for (var i = 0; i < btns.length; i++) btns[i].classList.toggle('active', btns[i] === btn);
-      toast('目标屏：' + ({ both: '全部（镜像）', main: '仅主屏', secondary: '仅副屏' }[screenTarget] || screenTarget));
-      return;
-    }
-
     // 预览
     if (btn.hasAttribute('data-preview')) { openPreview(btn.closest('.media-card')); return; }
 
@@ -141,10 +177,13 @@
     if (btn.hasAttribute('data-mqtt')) {
       var cmd = null;
       try { cmd = JSON.parse(btn.getAttribute('data-mqtt')); } catch (err) { toast('指令 JSON 错误', 'error'); return; }
-      // 双屏独立控制：除「双屏开关」外，注入目标屏（main/secondary/both）
-      if (cmd.action !== 'dual_screen') cmd.screen = screenTarget;
+      // 屏幕终端精准控制：除「双屏开关」外，注入目标 client_id + role；全空=全局广播
+      if (cmd.action !== 'dual_screen') { cmd.screen_id = screenId; cmd.screen_role = screenRole; }
+      var tgtTxt = screenId
+        ? (cmd.screen_role === 'main' ? '主屏' : cmd.screen_role === 'secondary' ? '副屏' : '屏幕') + '·' + String(screenId).slice(0, 10)
+        : '全部';
       post('/api/display/command', cmd, function (d) {
-        toast(d && d.ok !== false ? '指令已发送：' + (cmd.action || '') : '发送失败（MQTT 未连接？）',
+        toast(d && d.ok !== false ? ('指令已发送：' + (cmd.action || '') + ' → ' + tgtTxt) : '发送失败（MQTT 未连接？）',
               d && d.ok !== false ? 'ok' : 'error');
       });
       return;