feat: stats + chat + frontend pages (Stats, Chat, NavBar)

Backend:
- StatsManager.js: JSON persistence, leaderboard, rate-limit 1/5s
- ChatManager.js: 200-msg buffer, JSON persistence
- index.js: routes GET/POST /stats, /chat/history, /chat/send (Zod validation)
- ArenaRoom.js: chat handler broadcasts to room + persists via ChatManager

Unity:
- StatsTracker.cs: distance, maxSpeed, jumps, bumps, checkpoints, raceTime tracking
- ChatUI.cs: F3 toggle, bottom-right panel, polling 3s, unread badge
- NetworkManager.cs: SendChatMessage() + OnMessage<ChatUI.ChatMessage>(chat)
- CheckpointSystem.cs: RegisterCheckpoint/Finish hooks
- PlayerController.cs: RegisterJump/Bump hooks, physics rebalance, billboard fix
- GameHUD.cs: LocalRaceTimer, SetTotalRounds, OnRoundStart signature fix
- GameManager.cs: spectator cam reconnect fix

Frontend:
- NavBar.jsx: fixed top nav, Accueil/Stats/Chat/Jouer
- App.jsx: page state (home/play/stats/chat) + NavBar
- StatsPage.jsx: 6-tab leaderboard, auto-refresh 30s
- ChatPage.jsx: polling 3s, localStorage name, Enter to send

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

rolld_backend/game/src/chat/ChatManager.js

@@ -0,0 +1,52 @@
+const fs = require("fs");
+const path = require("path");
+
+const DATA_FILE = path.join(__dirname, "../../data/chat.json");
+const MAX_MESSAGES = 200;
+
+let _messages = [];
+let _nextId = 1;
+
+function _load() {
+  try {
+    if (fs.existsSync(DATA_FILE)) {
+      const data = JSON.parse(fs.readFileSync(DATA_FILE, "utf8"));
+      _messages = data.messages || [];
+      _nextId = data.nextId || (_messages.length + 1);
+    }
+  } catch (e) {
+    console.warn("[Chat] Failed to load chat.json:", e.message);
+  }
+}
+
+function _save() {
+  try {
+    fs.mkdirSync(path.dirname(DATA_FILE), { recursive: true });
+    fs.writeFileSync(DATA_FILE, JSON.stringify({ messages: _messages, nextId: _nextId }, null, 2));
+  } catch (e) {
+    console.warn("[Chat] Failed to save chat.json:", e.message);
+  }
+}
+
+function push(name, text) {
+  if (!name || !text || typeof name !== "string" || typeof text !== "string") return null;
+  name = name.slice(0, 32);
+  text = text.slice(0, 200);
+  if (text.trim().length === 0) return null;
+
+  const msg = { id: _nextId++, timestamp: Date.now(), name, text: text.trim() };
+  _messages.push(msg);
+  if (_messages.length > MAX_MESSAGES) _messages.splice(0, _messages.length - MAX_MESSAGES);
+  _save();
+  return msg;
+}
+
+function getHistory(since) {
+  const ts = Number(since) || 0;
+  return ts === 0 ? _messages.slice(-50) : _messages.filter((m) => m.timestamp > ts);
+}
+
+_load();
+console.log(`[Chat] Loaded ${_messages.length} message(s)`);
+
+module.exports = { push, getHistory };

rolld_backend/game/src/index.js

@@ -2,28 +2,98 @@ const cors = require('cors');
 const { Server } = require('@colyseus/core');
 const { WebSocketTransport } = require('@colyseus/ws-transport');
 const { ArenaRoom } = require('./rooms/ArenaRoom');
+const Stats = require('./stats/StatsManager');
+const Chat = require('./chat/ChatManager');
+const { z } = require('zod');
 
 const PORT = process.env.PORT || 2567;
 
-// Colyseus 0.17 – express callback receives the transport's internal Express app
+const statsUpdateSchema = z.object({
+  name: z.string().min(1).max(32),
+  stats: z.object({
+    totalDistance:    z.number().optional(),
+    totalJumps:       z.number().optional(),
+    maxSpeed:         z.number().optional(),
+    bestRaceTime:     z.number().optional(),
+    racesPlayed:      z.number().optional(),
+    qualifications:   z.number().optional(),
+    eliminations:     z.number().optional(),
+    checkpointsTotal: z.number().optional(),
+    bumpsGiven:       z.number().optional(),
+    totalPlaytime:    z.number().optional(),
+  }),
+});
+
+const chatSendSchema = z.object({
+  name: z.string().min(1).max(32),
+  text: z.string().min(1).max(200),
+});
+
+let _gameServer;
+
 const gameServer = new Server({
   transport: new WebSocketTransport(),
   express: (app) => {
     app.use(cors());
+    app.use(require('express').json());
 
     app.get('/health', (_req, res) => {
       res.json({ service: 'game', status: 'ok', timestamp: new Date().toISOString() });
     });
 
-    app.get('/', (_req, res) => {
-      res.send('🎮 Game server running');
+    app.get('/', (_req, res) => res.send('🎮 Game server running'));
+
+    // ── Stats ────────────────────────────────────────────────────────────
+    app.get('/stats', (_req, res) => {
+      res.json(Stats.getAll());
+    });
+
+    app.get('/stats/leaderboard/:key', (req, res) => {
+      const board = Stats.getLeaderboard(req.params.key);
+      if (!board) return res.status(400).json({ error: 'invalid key' });
+      res.json(board);
+    });
+
+    app.post('/stats/update', (req, res) => {
+      const parsed = statsUpdateSchema.safeParse(req.body);
+      if (!parsed.success) return res.status(400).json({ error: parsed.error.issues });
+      const ok = Stats.update(parsed.data.name, parsed.data.stats);
+      res.json({ ok });
+    });
+
+    // ── Chat ─────────────────────────────────────────────────────────────
+    app.get('/chat/history', (req, res) => {
+      res.json(Chat.getHistory(req.query.since));
+    });
+
+    app.post('/chat/send', (req, res) => {
+      const parsed = chatSendSchema.safeParse(req.body);
+      if (!parsed.success) return res.status(400).json({ error: parsed.error.issues });
+      const msg = Chat.push(parsed.data.name, parsed.data.text);
+      if (!msg) return res.status(429).json({ error: 'empty or invalid message' });
+
+      // Broadcast to all active Colyseus rooms
+      if (_gameServer) {
+        try {
+          const rooms = _gameServer.matchMaker?.rooms;
+          if (rooms) {
+            for (const room of rooms.values()) {
+              room.broadcast('chat', msg);
+            }
+          }
+        } catch (_) {}
+      }
+
+      res.json(msg);
     });
   },
 });
 
-// Define rooms
-gameServer.define('arena', ArenaRoom);
-console.log('✅ ArenaRoom registered');
+_gameServer = gameServer;
+
+gameServer.define('arena', ArenaRoom).then(() => {
+  console.log('✅ ArenaRoom registered');
+});
 
 gameServer.listen(PORT).then(() => {
   console.log(`🎮 Game server running on ws://localhost:${PORT}`);

rolld_backend/game/src/rooms/ArenaRoom.js

@@ -1,5 +1,6 @@
 const { Room } = require("@colyseus/core");
 const { GameState, Player } = require("../schema/GameState");
+const Chat = require("../chat/ChatManager");
 
 const LOBBY_TIMEOUT = 30;
 const COUNTDOWN_DURATION = 3;
@@ -46,6 +47,13 @@ class ArenaRoom extends Room {
       this._checkAllReady();
     });
 
+    this.onMessage("chat", (client, data) => {
+      const player = this.state.players.get(client.sessionId);
+      if (!player || !data.text) return;
+      const msg = Chat.push(player.name, data.text);
+      if (msg) this.broadcast("chat", msg);
+    });
+
     this.onMessage("checkpointReached", (client, data) => {
       if (this.state.phase !== "playing") return;
       const player = this.state.players.get(client.sessionId);

rolld_backend/game/src/stats/StatsManager.js

@@ -0,0 +1,101 @@
+const fs = require("fs");
+const path = require("path");
+
+const DATA_FILE = path.join(__dirname, "../../data/stats.json");
+
+const VALID_KEYS = [
+  "totalDistance", "totalJumps", "maxSpeed", "bestRaceTime",
+  "racesPlayed", "qualifications", "eliminations",
+  "checkpointsTotal", "bumpsGiven", "totalPlaytime",
+];
+
+let _stats = {};
+const _lastUpdate = new Map(); // name → timestamp, for rate-limiting
+
+function _load() {
+  try {
+    if (fs.existsSync(DATA_FILE)) {
+      _stats = JSON.parse(fs.readFileSync(DATA_FILE, "utf8"));
+    }
+  } catch (e) {
+    console.warn("[Stats] Failed to load stats.json, starting fresh:", e.message);
+    _stats = {};
+  }
+}
+
+function _save() {
+  try {
+    fs.mkdirSync(path.dirname(DATA_FILE), { recursive: true });
+    fs.writeFileSync(DATA_FILE, JSON.stringify(_stats, null, 2));
+  } catch (e) {
+    console.warn("[Stats] Failed to save stats.json:", e.message);
+  }
+}
+
+function _defaults() {
+  return {
+    totalDistance: 0,
+    totalJumps: 0,
+    maxSpeed: 0,
+    bestRaceTime: null,
+    racesPlayed: 0,
+    qualifications: 0,
+    eliminations: 0,
+    checkpointsTotal: 0,
+    bumpsGiven: 0,
+    totalPlaytime: 0,
+  };
+}
+
+function update(name, delta) {
+  if (!name || typeof name !== "string" || name.length > 32) return false;
+
+  const now = Date.now();
+  const last = _lastUpdate.get(name) || 0;
+  if (now - last < 5000) return false; // rate-limit: 1 update per 5s per player
+  _lastUpdate.set(name, now);
+
+  if (!_stats[name]) _stats[name] = _defaults();
+  const p = _stats[name];
+
+  for (const key of VALID_KEYS) {
+    if (delta[key] === undefined) continue;
+    const val = Number(delta[key]);
+    if (isNaN(val)) continue;
+
+    if (key === "maxSpeed") {
+      p.maxSpeed = Math.max(p.maxSpeed, val);
+    } else if (key === "bestRaceTime") {
+      if (val > 0 && (p.bestRaceTime === null || val < p.bestRaceTime)) {
+        p.bestRaceTime = val;
+      }
+    } else {
+      p[key] = (p[key] || 0) + val;
+    }
+  }
+
+  _save();
+  return true;
+}
+
+function getAll() {
+  return Object.entries(_stats).map(([name, s]) => ({ name, ...s }));
+}
+
+function getLeaderboard(key) {
+  if (!VALID_KEYS.includes(key)) return [];
+  return Object.entries(_stats)
+    .map(([name, s]) => ({ name, value: s[key] ?? 0 }))
+    .filter((e) => e.value !== null && e.value > 0)
+    .sort((a, b) => {
+      // bestRaceTime: lower is better
+      if (key === "bestRaceTime") return a.value - b.value;
+      return b.value - a.value;
+    })
+    .slice(0, 10);
+}
+
+_load();
+console.log(`[Stats] Loaded ${Object.keys(_stats).length} player(s)`);
+
+module.exports = { update, getAll, getLeaderboard, VALID_KEYS };