feat(admin/health): System Health Level 2 — метрики HTTP-запросов

backend/src/utils/metrics.js: лёгкие in-memory метрики (сброс при рестарте) —
всего запросов, req/min (скользящее окно), латентность avg/p50/p95/p99,
разбивка по статусам 2xx/3xx/4xx/5xx, топ маршрутов по частоте/латентности/
ошибкам (группировка по шаблону route.path, не по URL).

server.js: middleware (на /api, по res 'finish') пишет латентность и статус.
adminController.getMetrics + GET /api/admin/metrics (под admin-auth).

admin.js: health-страница переведена на refreshHealth/renderHealth (Level 1)
+ секция «Метрики запросов»: карточки req/min/всего/avg/p95/p99/5xx, цветная
полоса статусов, топ медленных/частых/ошибочных маршрутов.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/src/controllers/adminController.js

@@ -713,6 +713,12 @@ function getHealth(_req, res) {
   });
 }
 
+/* ── GET /api/admin/metrics — метрики HTTP-запросов (Level 2) ──────────── */
+const metrics = require('../utils/metrics');
+function getMetrics(_req, res) {
+  res.json(metrics.snapshot());
+}
+
 /* ── Topics CRUD ─────────────────────────────────────────────────────── */
 function getTopics(req, res) {
   const { subject_id } = req.query;
@@ -802,7 +808,7 @@ module.exports = {
   getUsers, updateRole, getUserSessions, getAllSessions, getSessionDetail,
   clearUserSessions, deleteSession, updateUser, banUser, deleteUser,
   getFeatures, updateFeatures, getFreeStudentFeatures, updateFreeStudentFeatures,
-  getAuditLog, clearAuditLog, getErrorLog, clearErrorLog, getHealth,
+  getAuditLog, clearAuditLog, getErrorLog, clearErrorLog, getHealth, getMetrics,
   getTopics, createTopic, updateTopic, deleteTopic,
   broadcast,
 };

backend/src/routes/admin.js

@@ -38,6 +38,7 @@ router.delete('/error-log',           ctrl.clearErrorLog);
 
 /* System health */
 router.get('/health',                 ctrl.getHealth);
+router.get('/metrics',                ctrl.getMetrics);
 
 /* Topics CRUD */
 router.get('/topics',                 ctrl.getTopics);

backend/src/server.js

@@ -138,6 +138,19 @@ const { requireFeature } = require('./middleware/features');
 app.use('/api/classroom', rateLimit({ windowMs: 60_000, max: 6000, message: 'Слишком много запросов' }));
 app.use('/api', rateLimit({ windowMs: 60_000, max: 600, message: 'Слишком много запросов, подождите минуту' }));
 
+/* ── Request metrics (System Health Level 2) ── */
+const metrics = require('./utils/metrics');
+app.use((req, res, next) => {
+  if (!req.originalUrl.startsWith('/api')) return next();
+  const start = process.hrtime.bigint();
+  res.on('finish', () => {
+    const ms = Number(process.hrtime.bigint() - start) / 1e6;
+    const route = (req.baseUrl || '') + (req.route && req.route.path ? req.route.path : '');
+    metrics.record(req.method, route || req.path || '(unmatched)', res.statusCode, ms);
+  });
+  next();
+});
+
 /* ── Routes ── */
 app.use('/api/auth',          authRoutes);
 app.use('/api/subjects',      subjectRoutes);

backend/src/utils/metrics.js

@@ -0,0 +1,67 @@
+'use strict';
+/*
+ * Лёгкие in-memory метрики HTTP-запросов для System Health (Level 2).
+ * Сбрасываются при перезапуске процесса. Память ограничена кольцевыми буферами.
+ * Группировка по шаблону маршрута (req.route.path), а не по конкретному URL —
+ * чтобы /api/biochem/molecules/:id не плодил тысячи ключей.
+ */
+const MAX_LAT = 3000;       // окно последних латентностей для перцентилей
+const WINDOW_MS = 60_000;   // окно для req/min
+
+let total = 0;
+let totalServerErrors = 0;
+const statusClasses = { '2xx': 0, '3xx': 0, '4xx': 0, '5xx': 0 };
+const routeStats = new Map();   // "METHOD /path" -> { count, totalMs, maxMs, errors }
+const latencies = [];           // последние латентности (мс)
+const recentTs = [];            // метки времени последних запросов (для req/min)
+const startedAt = Date.now();
+
+function record(method, route, status, ms) {
+  total++;
+  const cls = Math.floor(status / 100) + 'xx';
+  if (statusClasses[cls] !== undefined) statusClasses[cls]++;
+  if (status >= 500) totalServerErrors++;
+
+  const key = method + ' ' + route;
+  let r = routeStats.get(key);
+  if (!r) { r = { count: 0, totalMs: 0, maxMs: 0, errors: 0 }; routeStats.set(key, r); }
+  r.count++; r.totalMs += ms; if (ms > r.maxMs) r.maxMs = ms;
+  if (status >= 400) r.errors++;
+
+  latencies.push(ms);
+  if (latencies.length > MAX_LAT) latencies.shift();
+
+  const now = Date.now();
+  recentTs.push(now);
+  const cutoff = now - WINDOW_MS;
+  while (recentTs.length && recentTs[0] < cutoff) recentTs.shift();
+}
+
+function _pct(sorted, p) {
+  if (!sorted.length) return 0;
+  return sorted[Math.min(sorted.length - 1, Math.floor((p / 100) * sorted.length))];
+}
+
+function snapshot() {
+  const now = Date.now();
+  const cutoff = now - WINDOW_MS;
+  let reqPerMin = 0;
+  for (let i = recentTs.length - 1; i >= 0 && recentTs[i] >= cutoff; i--) reqPerMin++;
+  const sorted = [...latencies].sort((a, b) => a - b);
+  const avg = latencies.length ? latencies.reduce((s, x) => s + x, 0) / latencies.length : 0;
+  const routes = [...routeStats.entries()].map(([k, r]) => ({
+    route: k, count: r.count, avgMs: r.totalMs / r.count, maxMs: r.maxMs, errors: r.errors,
+  }));
+  return {
+    total, totalServerErrors, statusClasses,
+    reqPerMin,
+    avgMs: avg, p50: _pct(sorted, 50), p95: _pct(sorted, 95), p99: _pct(sorted, 99),
+    routeCount: routeStats.size,
+    sinceMs: now - startedAt,
+    topBusy:   [...routes].sort((a, b) => b.count - a.count).slice(0, 8),
+    topSlow:   [...routes].sort((a, b) => b.avgMs - a.avgMs).slice(0, 8),
+    topErrors: routes.filter(r => r.errors > 0).sort((a, b) => b.errors - a.errors).slice(0, 8),
+  };
+}
+
+module.exports = { record, snapshot };

frontend/js/admin/admin.js

@@ -299,55 +299,150 @@
   window.clearErrorLog = clearErrorLog;
 
   /* ═══ SYSTEM HEALTH ════════════════════════════════════════════════ */
+  let _healthLive = false, _healthTimer = null;
+
   async function loadHealth() {
     const el = document.getElementById('health-content');
     el.innerHTML = LS.skeleton(3, 'row');
+    await refreshHealth();
+    setupHealthTimer();
+  }
+
+  function setupHealthTimer() {
+    if (_healthTimer) { clearInterval(_healthTimer); _healthTimer = null; }
+    if (_healthLive) {
+      _healthTimer = setInterval(() => {
+        const el = document.getElementById('health-content');
+        if (!el || !el.offsetParent) { clearInterval(_healthTimer); _healthTimer = null; return; }
+        refreshHealth();
+      }, 5000);
+    }
+  }
+
+  async function refreshHealth() {
     try {
-      const h = await LS.api('/api/admin/health');
-      const fmtBytes = b => b > 1e9 ? (b/1e9).toFixed(1)+' GB' : b > 1e6 ? (b/1e6).toFixed(1)+' MB' : (b/1e3).toFixed(0)+' KB';
-      const fmtUp = s => { const d=Math.floor(s/86400), hr=Math.floor(s%86400/3600), m=Math.floor(s%3600/60); return d>0?`${d}d ${hr}h`:hr>0?`${hr}h ${m}m`:`${m}m`; };
-      el.innerHTML = `
-        <div style="display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:14px;margin-bottom:24px">
-          <div class="adm-panel" style="padding:18px;margin:0;text-align:center">
-            <div style="font-size:1.3rem;font-weight:800;font-family:'Unbounded',sans-serif;color:var(--green)">${fmtUp(h.uptime)}</div>
-            <div style="font-size:0.72rem;color:var(--text-3);font-weight:700;text-transform:uppercase;margin-top:4px">Uptime</div>
+      const [h, m] = await Promise.all([
+        LS.api('/api/admin/health'),
+        LS.api('/api/admin/metrics').catch(() => null),
+      ]);
+      renderHealth(h, m);
+    } catch (e) { const el = document.getElementById('health-content'); if (el) el.innerHTML = `<div style="color:var(--pink)">${esc(e.message)}</div>`; }
+  }
+
+  function renderHealth(h, m) {
+    const el = document.getElementById('health-content');
+    if (!el) return;
+    const fmtBytes = b => !b ? '0' : b > 1e9 ? (b/1e9).toFixed(1)+' GB' : b > 1e6 ? (b/1e6).toFixed(1)+' MB' : (b/1e3).toFixed(0)+' KB';
+    const fmtUp = s => { const d=Math.floor(s/86400), hr=Math.floor(s%86400/3600), mm=Math.floor(s%3600/60); return d>0?`${d}d ${hr}h`:hr>0?`${hr}h ${mm}m`:`${mm}m`; };
+    const stColor = h.status==='critical'?'var(--pink)':h.status==='warning'?'#facc15':'var(--green)';
+    const stLabel = h.status==='critical'?'Критическое состояние':h.status==='warning'?'Требует внимания':'Всё в норме';
+    const memPct = Math.round((h.memPercent||0)*100);
+    const memCol = memPct>92?'var(--pink)':memPct>80?'#facc15':'var(--green)';
+    const lag = h.eventLoopLagMs||0, lagCol = lag>200?'var(--pink)':lag>70?'#facc15':'var(--green)';
+    const card = (val, label, col) => `<div class="adm-panel" style="padding:16px;margin:0;text-align:center">
+      <div style="font-size:1.25rem;font-weight:800;font-family:'Unbounded',sans-serif;color:${col||'var(--text-1)'}">${val}</div>
+      <div style="font-size:0.68rem;color:var(--text-3);font-weight:700;text-transform:uppercase;margin-top:4px">${label}</div></div>`;
+    const maxRows = Math.max(1, ...(h.db.tables||[]).map(t=>t.rows));
+
+    // ── секция метрик запросов (Level 2) ──
+    let metricsHtml = '';
+    if (m) {
+      const sc = m.statusClasses||{}, tot = Math.max(1, (sc['2xx']||0)+(sc['3xx']||0)+(sc['4xx']||0)+(sc['5xx']||0));
+      const seg = (n,col)=> n>0?`<div style="width:${(n/tot*100).toFixed(1)}%;background:${col}" title="${n}"></div>`:'';
+      const routeRows = (arr, valFn, valLabel) => (arr&&arr.length)? arr.map(r=>`<div style="display:flex;align-items:center;gap:8px;margin:3px 0;font-size:.78rem">
+          <div style="flex:1;color:var(--text-2);overflow:hidden;text-overflow:ellipsis;white-space:nowrap">${esc(r.route)}</div>
+          <div style="width:90px;text-align:right;font-weight:600;color:var(--text-3)">${valFn(r)}</div></div>`).join('')
+        : `<div style="color:var(--text-3);font-size:.78rem">нет данных</div>`;
+      const lagP = (v)=> (v||0)>200?'var(--pink)':(v||0)>70?'#facc15':'var(--text-1)';
+      metricsHtml = `
+        <div class="adm-panel" style="margin:14px 0 0">
+          <div class="adm-panel-title">Метрики запросов <span style="color:var(--text-3);font-weight:400;font-size:.78rem">(с рестарта · ${fmtUp(Math.floor((m.sinceMs||0)/1000))})</span></div>
+          <div style="display:grid;grid-template-columns:repeat(auto-fill,minmax(100px,1fr));gap:10px;margin:8px 0 14px">
+            ${card(m.reqPerMin, 'Req/min', 'var(--green)')}
+            ${card((m.total||0).toLocaleString('ru'), 'Всего')}
+            ${card((m.avgMs||0).toFixed(0)+' мс', 'Средн.')}
+            ${card((m.p95||0).toFixed(0)+' мс', 'p95', lagP(m.p95))}
+            ${card((m.p99||0).toFixed(0)+' мс', 'p99', lagP(m.p99))}
+            ${card(sc['5xx']||0, '5xx', (sc['5xx']||0)>0?'var(--pink)':'var(--green)')}
           </div>
-          <div class="adm-panel" style="padding:18px;margin:0;text-align:center">
-            <div style="font-size:1.3rem;font-weight:800;font-family:'Unbounded',sans-serif;color:var(--violet)">${fmtBytes(h.db.sizeBytes)}</div>
-            <div style="font-size:0.72rem;color:var(--text-3);font-weight:700;text-transform:uppercase;margin-top:4px">База данных</div>
+          <div style="font-size:.72rem;color:var(--text-3);margin-bottom:5px">Статусы: 2xx ${sc['2xx']||0} · 3xx ${sc['3xx']||0} · 4xx ${sc['4xx']||0} · 5xx ${sc['5xx']||0}</div>
+          <div style="display:flex;height:9px;border-radius:5px;overflow:hidden;background:rgba(255,255,255,.06);margin-bottom:14px">
+            ${seg(sc['2xx'],'#4ade80')}${seg(sc['3xx'],'#60a5fa')}${seg(sc['4xx'],'#facc15')}${seg(sc['5xx'],'#f87171')}
           </div>
-          <div class="adm-panel" style="padding:18px;margin:0;text-align:center">
-            <div style="font-size:1.3rem;font-weight:800;font-family:'Unbounded',sans-serif">${fmtBytes(h.uploads.sizeBytes)}</div>
-            <div style="font-size:0.72rem;color:var(--text-3);font-weight:700;text-transform:uppercase;margin-top:4px">Файлы</div>
-          </div>
-          <div class="adm-panel" style="padding:18px;margin:0;text-align:center">
-            <div style="font-size:1.3rem;font-weight:800;font-family:'Unbounded',sans-serif;color:${h.recentErrors>0?'var(--pink)':'var(--green)'}">${h.recentErrors}</div>
-            <div style="font-size:0.72rem;color:var(--text-3);font-weight:700;text-transform:uppercase;margin-top:4px">Ошибок за 24ч</div>
-          </div>
-        </div>
-        <div style="display:grid;grid-template-columns:1fr 1fr;gap:14px">
-          <div class="adm-panel" style="margin:0">
-            <div class="adm-panel-title">Платформа</div>
-            <table style="width:100%;font-size:0.88rem">
-              <tr><td style="color:var(--text-3);padding:4px 0">Node.js</td><td style="font-weight:600">${h.node}</td></tr>
-              <tr><td style="color:var(--text-3);padding:4px 0">OS</td><td style="font-weight:600">${h.platform}</td></tr>
-              <tr><td style="color:var(--text-3);padding:4px 0">CPU ядра</td><td style="font-weight:600">${h.cpus}</td></tr>
-              <tr><td style="color:var(--text-3);padding:4px 0">RAM использовано</td><td style="font-weight:600">${fmtBytes(h.memory.rss)}</td></tr>
-              <tr><td style="color:var(--text-3);padding:4px 0">RAM heap</td><td style="font-weight:600">${fmtBytes(h.memory.heapUsed)}</td></tr>
-              <tr><td style="color:var(--text-3);padding:4px 0">RAM свободно</td><td style="font-weight:600">${fmtBytes(h.freeMem)} / ${fmtBytes(h.totalMem)}</td></tr>
-            </table>
-          </div>
-          <div class="adm-panel" style="margin:0">
-            <div class="adm-panel-title">Данные</div>
-            <table style="width:100%;font-size:0.88rem">
-              <tr><td style="color:var(--text-3);padding:4px 0">Пользователей</td><td style="font-weight:600">${h.db.totalUsers}</td></tr>
-              <tr><td style="color:var(--text-3);padding:4px 0">Всего сессий</td><td style="font-weight:600">${h.db.totalSessions}</td></tr>
-              <tr><td style="color:var(--text-3);padding:4px 0">Сессий сегодня</td><td style="font-weight:600;color:var(--violet)">${h.db.todaySessions}</td></tr>
-              <tr><td style="color:var(--text-3);padding:4px 0">Вопросов в базе</td><td style="font-weight:600">${h.db.totalQuestions}</td></tr>
-            </table>
+          <div style="display:grid;grid-template-columns:1fr 1fr;gap:16px">
+            <div><div style="font-size:.72rem;color:var(--text-3);font-weight:700;text-transform:uppercase;margin-bottom:4px">Самые медленные</div>${routeRows(m.topSlow, r=>r.avgMs.toFixed(0)+' мс')}</div>
+            <div><div style="font-size:.72rem;color:var(--text-3);font-weight:700;text-transform:uppercase;margin-bottom:4px">Самые частые</div>${routeRows(m.topBusy, r=>r.count.toLocaleString('ru'))}</div>
           </div>
+          ${(m.topErrors&&m.topErrors.length)?`<div style="margin-top:12px"><div style="font-size:.72rem;color:var(--pink);font-weight:700;text-transform:uppercase;margin-bottom:4px">Маршруты с ошибками</div>${routeRows(m.topErrors, r=>r.errors+' ош. / '+r.count)}</div>`:''}
         </div>`;
-    } catch (e) { el.innerHTML = `<div style="color:var(--pink)">${esc(e.message)}</div>`; }
+    }
+
+    el.innerHTML = `
+      <div class="adm-panel" style="margin:0 0 16px;padding:14px 18px;display:flex;align-items:center;gap:14px;border-left:4px solid ${stColor}">
+        <div style="width:13px;height:13px;border-radius:50%;background:${stColor};box-shadow:0 0 12px ${stColor};flex-shrink:0"></div>
+        <div style="flex:1;min-width:0">
+          <div style="font-weight:800;font-family:'Unbounded',sans-serif;color:${stColor}">${stLabel}</div>
+          <div style="font-size:.78rem;color:var(--text-3);margin-top:2px">${h.reasons&&h.reasons.length?h.reasons.map(esc).join('  ·  '):'Все показатели в пределах нормы'}</div>
+        </div>
+        <button id="health-live-btn" style="height:30px;padding:0 14px;border-radius:8px;border:1.5px solid rgba(255,255,255,.14);background:rgba(255,255,255,.05);color:${_healthLive?'var(--green)':'var(--text-3)'};font-weight:700;font-size:.78rem;cursor:pointer;white-space:nowrap">${_healthLive?'● Live':'○ Авто-обновление'}</button>
+      </div>
+
+      <div style="display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:12px;margin-bottom:18px">
+        ${card(fmtUp(h.uptime), 'Uptime', 'var(--green)')}
+        ${card(fmtBytes(h.db.sizeBytes), 'База данных', 'var(--violet)')}
+        ${card(fmtBytes(h.uploads.sizeBytes), 'Файлы')}
+        ${card(h.recentErrors, 'Ошибок 24ч', h.recentErrors>0?'var(--pink)':'var(--green)')}
+        ${card((h.sse?h.sse.connections:0), 'SSE онлайн', 'var(--green)')}
+        ${card(memPct+'%', 'Память', memCol)}
+        ${card(lag.toFixed(0)+' мс', 'Event-loop', lagCol)}
+        ${card(h.disk?fmtBytes(h.disk.freeBytes)+' своб.':'—', 'Диск')}
+      </div>
+
+      <div style="display:grid;grid-template-columns:1fr 1fr;gap:14px">
+        <div class="adm-panel" style="margin:0">
+          <div class="adm-panel-title">Платформа</div>
+          <table style="width:100%;font-size:0.86rem">
+            <tr><td style="color:var(--text-3);padding:3px 0">Версия</td><td style="font-weight:600">${esc(h.version||'?')} ${h.commit?`<span style="color:var(--text-3);font-family:monospace">${esc(h.commit)}</span>`:''}</td></tr>
+            <tr><td style="color:var(--text-3);padding:3px 0">Окружение</td><td style="font-weight:600">${esc(h.env||'?')} · PID ${h.pid||'?'}</td></tr>
+            <tr><td style="color:var(--text-3);padding:3px 0">Node.js</td><td style="font-weight:600">${esc(h.node)}</td></tr>
+            <tr><td style="color:var(--text-3);padding:3px 0">OS / арх</td><td style="font-weight:600">${esc(h.platform)} ${esc(h.arch||'')}</td></tr>
+            <tr><td style="color:var(--text-3);padding:3px 0">CPU ядра · load</td><td style="font-weight:600">${h.cpus} · ${(h.loadavg||[0]).map(x=>x.toFixed(2)).join(' / ')}</td></tr>
+            <tr><td style="color:var(--text-3);padding:3px 0">RAM rss / heap</td><td style="font-weight:600">${fmtBytes(h.memory.rss)} / ${fmtBytes(h.memory.heapUsed)}</td></tr>
+            <tr><td style="color:var(--text-3);padding:3px 0">RAM система</td><td style="font-weight:600">${fmtBytes(h.totalMem-h.freeMem)} / ${fmtBytes(h.totalMem)}</td></tr>
+            ${h.disk?`<tr><td style="color:var(--text-3);padding:3px 0">Диск</td><td style="font-weight:600">${fmtBytes(h.disk.freeBytes)} своб. / ${fmtBytes(h.disk.totalBytes)}</td></tr>`:''}
+          </table>
+        </div>
+        <div class="adm-panel" style="margin:0">
+          <div class="adm-panel-title">Данные и активность</div>
+          <table style="width:100%;font-size:0.86rem">
+            <tr><td style="color:var(--text-3);padding:3px 0">Пользователей</td><td style="font-weight:600">${h.db.totalUsers}</td></tr>
+            <tr><td style="color:var(--text-3);padding:3px 0">Онлайн (SSE)</td><td style="font-weight:600;color:var(--green)">${h.sse?h.sse.users:0} польз. · ${h.sse?h.sse.connections:0} соед.</td></tr>
+            <tr><td style="color:var(--text-3);padding:3px 0">Всего сессий</td><td style="font-weight:600">${h.db.totalSessions}</td></tr>
+            <tr><td style="color:var(--text-3);padding:3px 0">Сессий сегодня</td><td style="font-weight:600;color:var(--violet)">${h.db.todaySessions}</td></tr>
+            <tr><td style="color:var(--text-3);padding:3px 0">Вопросов в базе</td><td style="font-weight:600">${h.db.totalQuestions}</td></tr>
+            <tr><td style="color:var(--text-3);padding:3px 0">WAL</td><td style="font-weight:600">${fmtBytes(h.db.walBytes||0)}</td></tr>
+          </table>
+        </div>
+      </div>
+
+      ${metricsHtml}
+
+      <div class="adm-panel" style="margin:14px 0 0">
+        <div class="adm-panel-title">Крупнейшие таблицы БД</div>
+        ${(h.db.tables||[]).map(t=>`<div style="display:flex;align-items:center;gap:10px;margin:4px 0">
+          <div style="width:170px;font-size:.8rem;color:var(--text-2);overflow:hidden;text-overflow:ellipsis;white-space:nowrap">${esc(t.name)}</div>
+          <div style="flex:1;height:7px;background:rgba(255,255,255,.06);border-radius:4px;overflow:hidden"><div style="height:100%;width:${Math.round(t.rows/maxRows*100)}%;background:var(--violet);border-radius:4px"></div></div>
+          <div style="width:60px;text-align:right;font-size:.78rem;font-weight:600">${t.rows.toLocaleString('ru')}</div>
+        </div>`).join('')}
+      </div>`;
+
+    const btn = document.getElementById('health-live-btn');
+    if (btn) btn.addEventListener('click', () => {
+      _healthLive = !_healthLive;
+      btn.textContent = _healthLive ? '● Live' : '○ Авто-обновление';
+      btn.style.color = _healthLive ? 'var(--green)' : 'var(--text-3)';
+      setupHealthTimer();
+    });
   }
 
   /* ════════════════════════════════════════════════