feat(elo): add ELO rating system

- DB: elo column on user table (default 1200, added via ALTER TABLE IF NOT EXISTS)
- ELO calculated after every game save (K=32, min 100)
- Bots use their fixed ELO values; only human players' ELO changes
- AI page games save with bot name (e.g. 'Holzpferd Heinz') instead of 'Stockfish'
- User profile shows ELO badge below name
- Header shows current ELO for logged-in users (links to profile)

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

client/src/app/ai/page.tsx

@@ -42,7 +42,7 @@ export default function AiGamePage() {
         method: "POST",
         credentials: "include",
         headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ pgn: g.pgn(), winner, endReason, playerColor: color, level, startedAt: startedAtRef.current })
+        body: JSON.stringify({ pgn: g.pgn(), winner, endReason, playerColor: color, level, botName: selectedBot.name, startedAt: startedAtRef.current })
       });
       if (res.ok) {
         const { id } = await res.json();

client/src/app/user/[name]/page.tsx

@@ -43,7 +43,12 @@ export default async function Profile({ params }: { params: { name: string } })
   return (
     <div className="mt-8 flex w-full flex-col gap-8">
       <div className="flex flex-wrap items-center justify-between gap-4 md:gap-8">
+        <div>
           <h1 className="text-4xl font-bold">{data.name}</h1>
+          {data.elo != null && (
+            <span className="badge badge-primary badge-lg mt-1 font-mono">{data.elo} ELO</span>
+          )}
+        </div>
         <div className="flex gap-6">
           <div className="flex flex-col items-center">
             <span className="text-sm">Wins</span>

client/src/components/Header.tsx

@@ -37,6 +37,11 @@ export default function Header() {
           </Link>
         )}
         {user?.id && typeof user.id === "number" && <NotificationPanel />}
+        {user?.elo != null && typeof user.id === "number" && (
+          <Link href={`/user/${user.name}`} className="btn btn-ghost btn-sm font-mono tabular-nums" title="Deine ELO-Wertung">
+            {user.elo}
+          </Link>
+        )}
         <ThemeToggle />
         <label tabIndex={0} htmlFor="auth-modal" className="btn btn-ghost btn-circle avatar">
           <div className="w-10 rounded-full">

server/src/controllers/auth.controller.ts

@@ -223,6 +223,7 @@ export const loginUser = async (req: Request, res: Response) => {
             wins: users[0].wins,
             losses: users[0].losses,
             draws: users[0].draws,
+            elo: users[0].elo,
             role: users[0].role
         };
         req.session.save(() => {

server/src/controllers/users.controller.ts

@@ -22,7 +22,8 @@ export const getUserProfile = async (req: Request, res: Response) => {
             name: users[0].name,
             wins: users[0].wins,
             losses: users[0].losses,
-            draws: users[0].draws
+            draws: users[0].draws,
+            elo: users[0].elo
         };
 
         res.status(200).json({ ...publicUser, recentGames });

server/src/db/index.ts

@@ -49,6 +49,7 @@ export const INIT_TABLES = /* sql */ `
     ALTER TABLE "game" ADD COLUMN IF NOT EXISTS vs_ai BOOLEAN DEFAULT FALSE;
     ALTER TABLE "game" ADD COLUMN IF NOT EXISTS ai_level INTEGER;
     ALTER TABLE "game" ADD COLUMN IF NOT EXISTS time_control INTEGER;
+    ALTER TABLE "user" ADD COLUMN IF NOT EXISTS elo INTEGER DEFAULT 1200;
 
     CREATE TABLE IF NOT EXISTS "correspondence_game" (
         id SERIAL PRIMARY KEY,

server/src/db/models/game.model.ts

@@ -1,8 +1,46 @@
 import type { Game, User } from "@michess/types";
 import { db } from "../index.js";
+import { BOTS } from "../../bots.js";
 
 export const activeGames: Game[] = [];
 
+const ELO_K = 32;
+
+async function updateElo(game: Game): Promise<void> {
+    if (!game.winner) return;
+    const whiteId = typeof game.white?.id === "number" ? game.white.id : undefined;
+    const blackId = typeof game.black?.id === "number" ? game.black.id : undefined;
+    if (!whiteId && !blackId) return;
+
+    let whiteElo = 1200, blackElo = 1200;
+    let whiteIsBot = false, blackIsBot = false;
+
+    if (whiteId) {
+        const r = await db.query(`SELECT elo, role FROM "user" WHERE id=$1`, [whiteId]);
+        if (r.rows[0]) { whiteElo = r.rows[0].elo ?? 1200; whiteIsBot = r.rows[0].role === "bot"; }
+    } else {
+        const bot = BOTS.find(b => b.name === game.white?.name);
+        if (bot) { whiteElo = bot.elo; whiteIsBot = true; }
+    }
+    if (blackId) {
+        const r = await db.query(`SELECT elo, role FROM "user" WHERE id=$1`, [blackId]);
+        if (r.rows[0]) { blackElo = r.rows[0].elo ?? 1200; blackIsBot = r.rows[0].role === "bot"; }
+    } else {
+        const bot = BOTS.find(b => b.name === game.black?.name);
+        if (bot) { blackElo = bot.elo; blackIsBot = true; }
+    }
+
+    if (whiteIsBot && blackIsBot) return;
+
+    const actualWhite = game.winner === "white" ? 1 : game.winner === "draw" ? 0.5 : 0;
+    const expectedWhite = 1 / (1 + Math.pow(10, (blackElo - whiteElo) / 400));
+    const newWhiteElo = Math.max(100, Math.round(whiteElo + ELO_K * (actualWhite - expectedWhite)));
+    const newBlackElo = Math.max(100, Math.round(blackElo + ELO_K * ((1 - actualWhite) - (1 - expectedWhite))));
+
+    if (whiteId && !whiteIsBot) await db.query(`UPDATE "user" SET elo=$1 WHERE id=$2`, [newWhiteElo, whiteId]);
+    if (blackId && !blackIsBot) await db.query(`UPDATE "user" SET elo=$1 WHERE id=$2`, [newBlackElo, blackId]);
+}
+
 export const save = async (game: Game) => {
     try {
         const white: User = { name: game.white?.name };
@@ -50,6 +88,7 @@ export const save = async (game: Game) => {
                     ]);
                 }
             }
+            await updateElo(game);
         }
         return {
             id: res.rows[0].id,

server/src/db/models/user.model.ts

@@ -8,7 +8,7 @@ export const create = async (user: User, password: string) => {
 
     try {
         const res = await db.query(
-            `INSERT INTO "user"(name, email, password) VALUES($1, $2, $3) RETURNING id, name, email, wins, losses, draws, role, banned`,
+            `INSERT INTO "user"(name, email, password) VALUES($1, $2, $3) RETURNING id, name, email, wins, losses, draws, elo, role, banned`,
             [user.name, user.email || null, password]
         );
         return res.rows[0] as User;
@@ -24,7 +24,7 @@ export const findById = async (id: number) => {
     }
     try {
         const res = await db.query(
-            `SELECT id, name, email, wins, losses, draws, role, banned FROM "user" WHERE id=$1`,
+            `SELECT id, name, email, wins, losses, draws, elo, role, banned FROM "user" WHERE id=$1`,
             [id]
         );
         if (res.rowCount) {
@@ -40,7 +40,7 @@ export const findByNameEmail = async (user: User, includePassword = false, limit
     if (!user) {
         try {
             const res = await db.query(
-                `SELECT id, name, email, wins, losses, draws, role, banned FROM "user" LIMIT $1`,
+                `SELECT id, name, email, wins, losses, draws, elo, role, banned FROM "user" LIMIT $1`,
                 [limit ?? 10]
             );
             return res.rows as (User & { password?: string; banned?: boolean })[];
@@ -52,7 +52,7 @@ export const findByNameEmail = async (user: User, includePassword = false, limit
 
     try {
         const res = await db.query(
-            `SELECT id, name, email, wins, losses, draws, role, banned${
+            `SELECT id, name, email, wins, losses, draws, elo, role, banned${
                 includePassword ? `, password` : ""
             } FROM "user" WHERE name=$1 OR email=$2 LIMIT $3`,
             [user.name, user.email, limit ?? 1]
@@ -67,7 +67,7 @@ export const findByNameEmail = async (user: User, includePassword = false, limit
 export const searchByName = async (query: string, limit = 10) => {
     try {
         const res = await db.query(
-            `SELECT id, name, wins, losses, draws FROM "user" WHERE name ILIKE $1 LIMIT $2`,
+            `SELECT id, name, wins, losses, draws, elo FROM "user" WHERE name ILIKE $1 LIMIT $2`,
             [`%${query}%`, limit]
         );
         return res.rows as User[];
@@ -83,11 +83,11 @@ export const update = async (id: number, updatedUser: User & { password?: string
     }
 
     try {
-        let query = `UPDATE "user" SET name=$1, email=$2 WHERE id=$3 RETURNING id, name, email, wins, losses, draws, role, banned`;
+        let query = `UPDATE "user" SET name=$1, email=$2 WHERE id=$3 RETURNING id, name, email, wins, losses, draws, elo, role, banned`;
         let values: (string | number | null | undefined)[] = [updatedUser.name, updatedUser.email, id];
 
         if (updatedUser.password) {
-            query = `UPDATE "user" SET name=$1, email=$2, password=$3 WHERE id=$4 RETURNING id, name, email, wins, losses, draws, role, banned`;
+            query = `UPDATE "user" SET name=$1, email=$2, password=$3 WHERE id=$4 RETURNING id, name, email, wins, losses, draws, elo, role, banned`;
             values = [updatedUser.name, updatedUser.email, updatedUser.password, id];
         }
         const res = await db.query(query, values);
@@ -129,7 +129,7 @@ export const adminUpdate = async (id: number, fields: { role?: string; banned?:
 
 export const getAllUsers = async (limit = 50, offset = 0, search?: string) => {
     try {
-        let query = `SELECT id, name, email, wins, losses, draws, role, banned, created_at FROM "user"`;
+        let query = `SELECT id, name, email, wins, losses, draws, elo, role, banned, created_at FROM "user"`;
         const values: (string | number)[] = [];
 
         if (search) {

server/src/routes/ai.route.ts

@@ -33,7 +33,7 @@ router.get("/levels", (_req: Request, res: Response) => {
 
 router.post("/save", requireAuth, async (req: Request, res: Response) => {
     try {
-        const { pgn, winner, endReason, playerColor, level, startedAt } = req.body;
+        const { pgn, winner, endReason, playerColor, level, startedAt, botName } = req.body;
         const user = req.session.user!;
 
         if (!pgn || !winner || !endReason || !playerColor) {
@@ -42,7 +42,7 @@ router.post("/save", requireAuth, async (req: Request, res: Response) => {
         }
 
         const humanPlayer = { id: user.id as number, name: user.name };
-        const aiPlayer = { name: `Stockfish` };
+        const aiPlayer = { name: botName || `Stockfish` };
 
         const game: Game = {
             pgn,

types/index.d.ts

@@ -27,6 +27,7 @@ export interface User {
     wins?: number;
     losses?: number;
     draws?: number;
+    elo?: number;
     role?: "user" | "admin";
 
     // mainly for players, not spectators