feat: anonymous heartbeat + network stats on leaderboard (#114)

- Server sends anonymous heartbeat on startup (anonId, version, platform, agent counts)
- Worker tracks active installs (48h TTL) and daily active users
- Public leaderboard shows: on leaderboard / vibe coders online / active today
- codedash UI shows network stats bar
- Updated Worker HTML with tabs (Today/Week/All Time), GitHub links, agent badges
- Week stats sent from client for weekly ranking
- Export getOrCreateAnonId from data.js

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: vakovalskii

src/data.js

@@ -2403,6 +2403,7 @@ module.exports = {
   loadSessionDetail,
   getProjectGitInfo,
   getLeaderboardStats,
+  getOrCreateAnonId,
   deleteSession,
   getGitCommits,
   exportSessionMarkdown,

src/frontend/app.js

@@ -2729,6 +2729,14 @@ async function loadGlobalLeaderboard() {
   try {
     var resp = await fetch('/api/leaderboard/remote');
     _lbRemoteData = await resp.json();
+    // Show network stats
+    var net = _lbRemoteData.network || {};
+    var netEl = document.getElementById('networkStats');
+    if (netEl) {
+      netEl.innerHTML = '<span>' + (_lbRemoteData.totalUsers || 0) + ' on leaderboard</span>' +
+        '<span>' + (net.totalInstalls || 0) + ' vibe coders online</span>' +
+        '<span>' + (net.todayActive || 0) + ' active today</span>';
+    }
     renderGlobalBoard();
   } catch { if (board) board.innerHTML = '<div style="text-align:center;padding:20px;color:var(--text-muted)">Could not load global leaderboard</div>'; }
 }
@@ -2882,6 +2890,9 @@ async function renderLeaderboard(container) {
     }
 
     // Global leaderboard
+    // Network stats
+    html += '<div class="lb-network" id="networkStats"><span>Loading network...</span></div>';
+
     // Global leaderboard with tabs
     html += '<div class="lb-section-title">Global Leaderboard</div>';
     html += '<div class="lb-tabs">';

src/frontend/styles.css

@@ -2085,6 +2085,20 @@ body {
     user-select: all;
 }
 
+.lb-network {
+    display: flex;
+    justify-content: center;
+    gap: 24px;
+    padding: 12px 16px;
+    background: linear-gradient(135deg, rgba(99,102,241,0.08), rgba(168,85,247,0.08));
+    border: 1px solid rgba(139,92,246,0.2);
+    border-radius: 10px;
+    margin: 16px 0;
+    font-size: 13px;
+    color: var(--text-muted);
+}
+.lb-network span { font-weight: 600; }
+
 .lb-sync-bar {
     text-align: center;
     margin: 20px 0;

src/server.js

@@ -437,9 +437,40 @@ function startServer(host, port, openBrowser = true) {
         exec(`xdg-open ${browserUrl}`);
       }
     }
+
+    // Anonymous heartbeat — count active installs
+    sendHeartbeat();
   });
 }
 
+function sendHeartbeat() {
+  try {
+    const { getOrCreateAnonId } = require('./data');
+    const anon = getOrCreateAnonId();
+    const pkg = require('../package.json');
+    const sessions = require('./data').loadSessions();
+    const agentCounts = {};
+    sessions.forEach(s => { agentCounts[s.tool] = (agentCounts[s.tool] || 0) + 1; });
+
+    const body = JSON.stringify({
+      anonId: anon.id,
+      version: pkg.version,
+      platform: process.platform,
+      agents: agentCounts,
+    });
+
+    const req = https.request({
+      hostname: 'codedash-leaderboard.valeriy.workers.dev',
+      path: '/api/heartbeat', method: 'POST',
+      headers: { 'Content-Type': 'application/json', 'Content-Length': Buffer.byteLength(body) },
+      timeout: 5000,
+    });
+    req.on('error', () => {}); // silent fail
+    req.write(body);
+    req.end();
+  } catch {}
+}
+
 // ── Helpers ─────────────────────────────────
 function json(res, data, status = 200) {
   res.writeHead(status, { 'Content-Type': 'application/json' });