feat: honest AI opponent in quick game

New Game's quick game gains an explicit opponent selector — 🤖 AI (default)
or 👤 Random player. AI starts a game seated with a pooled robot that joins
and moves at once: no per-move timeout (a 7-day inactivity loss reusing the
turn-timeout sweeper), chat/nudge disabled, no statistics, the opponent shown
as 🤖 everywhere. The random path (disguised robot) is unchanged.

Driven by one game flag (games.vs_ai), set only on AI-started games so the
disguised path is never revealed; Matchmaker.StartVsAI seats the robot
directly (no open pool); the robot replies event-driven via the game service's
after-commit/after-create hook. Wire: vs_ai on EnqueueRequest + GameView.

ui/src/game/Chat.svelte

@@ -12,6 +12,7 @@
     canNudge = false,
     waiting = false,
     nudgeOnCooldown = false,
+    vsAi = false,
     onsend,
     onnudge,
   }: {
@@ -34,6 +35,9 @@
     // are disabled (there is no one to message or hurry yet).
     waiting?: boolean;
     nudgeOnCooldown?: boolean;
+    // vsAi disables both controls in an honest-AI game: the opponent is a robot, so there is
+    // nobody to message or hurry. The fields still show (turn-driven), but disabled.
+    vsAi?: boolean;
     onsend: (text: string) => void;
     onnudge: () => void;
   } = $props();
@@ -67,9 +71,10 @@
         maxlength="60"
         placeholder={t('chat.placeholder')}
         bind:value={text}
-        onkeydown={(e) => e.key === 'Enter' && !busy && send()}
+        disabled={vsAi}
+        onkeydown={(e) => e.key === 'Enter' && !busy && !vsAi && send()}
       />
-      <button class="iconbtn" onclick={send} disabled={busy || waiting || !connection.online} aria-label={t('chat.send')}>⬆️</button>
+      <button class="iconbtn" onclick={send} disabled={busy || waiting || vsAi || !connection.online} aria-label={t('chat.send')}>⬆️</button>
     {:else if myTurn}
       <!-- Own turn, the one allowed message already sent: a caption holds the row until the
            next turn (no nudge — there is no one to hurry on your own turn). -->
@@ -77,7 +82,7 @@
     {:else if canNudge}
       <!-- A flex:1 caption keeps the nudge pinned right whether or not the cooldown text shows. -->
       <span class="cooldown">{nudgeOnCooldown ? t('chat.awaitingReply') : ''}</span>
-      <button class="iconbtn" onclick={onnudge} disabled={busy || waiting || nudgeOnCooldown || !connection.online} aria-label={t('chat.nudgeAction')}>🛎️</button>
+      <button class="iconbtn" onclick={onnudge} disabled={busy || waiting || nudgeOnCooldown || vsAi || !connection.online} aria-label={t('chat.nudgeAction')}>🛎️</button>
     {/if}
   </div>
 </div>

ui/src/game/ChatScreen.svelte

@@ -113,4 +113,16 @@
   }
 </script>
 
-<Chat {messages} {myId} {busy} myTurn={isMyTurn} {canSend} {canNudge} {waiting} {nudgeOnCooldown} onsend={sendChat} onnudge={nudge} />
+<Chat
+  {messages}
+  {myId}
+  {busy}
+  myTurn={isMyTurn}
+  {canSend}
+  {canNudge}
+  {waiting}
+  {nudgeOnCooldown}
+  vsAi={!!view && view.game.vsAi}
+  onsend={sendChat}
+  onnudge={nudge}
+/>

ui/src/game/Game.svelte

@@ -869,6 +869,8 @@
   function seatName(s: { accountId: string; displayName: string } | undefined): string {
     if (!s) return '';
     if (s.accountId === app.session?.userId) return t('common.you');
+    // An honest-AI game shows the robot opponent as 🤖, never its (pooled human-like) name.
+    if (view?.game.vsAi) return '🤖';
     if (!s.accountId) return t('game.searchingForOpponent');
     return s.displayName;
   }
@@ -876,6 +878,7 @@
   // turnLabel is the under-board status when it is not the viewer's turn: the opponent's name
   // once they have joined, or a generic "opponent's turn" while the seat is still empty (waiting).
   function turnLabel(): string {
+    if (view?.game.vsAi) return '🤖';
     const s = view?.game.seats[view?.game.toMove ?? -1];
     if (s && s.accountId && s.accountId !== app.session?.userId) return s.displayName;
     return t('game.opponentsTurn');
@@ -885,6 +888,8 @@
   // (not the still-empty seat of an open game) who is not yet a friend (an already-requested
   // opponent still shows it, but disabled).
   function canAddFriend(accountId: string): boolean {
+    // Never offer add-friend against an AI opponent.
+    if (view?.game.vsAi) return false;
     return !!accountId && !app.profile?.isGuest && accountId !== app.session?.userId && !friends.has(accountId);
   }
 </script>

ui/src/gen/fbs/scrabblefb/enqueue-request.ts

@@ -32,8 +32,13 @@ multipleWordsPerTurn():boolean {
   return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : false;
 }
 
+vsAi():boolean {
+  const offset = this.bb!.__offset(this.bb_pos, 8);
+  return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : false;
+}
+
 static startEnqueueRequest(builder:flatbuffers.Builder) {
-  builder.startObject(2);
+  builder.startObject(3);
 }
 
 static addVariant(builder:flatbuffers.Builder, variantOffset:flatbuffers.Offset) {
@@ -44,15 +49,20 @@ static addMultipleWordsPerTurn(builder:flatbuffers.Builder, multipleWordsPerTurn
   builder.addFieldInt8(1, +multipleWordsPerTurn, +false);
 }
 
+static addVsAi(builder:flatbuffers.Builder, vsAi:boolean) {
+  builder.addFieldInt8(2, +vsAi, +false);
+}
+
 static endEnqueueRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;
 }
 
-static createEnqueueRequest(builder:flatbuffers.Builder, variantOffset:flatbuffers.Offset, multipleWordsPerTurn:boolean):flatbuffers.Offset {
+static createEnqueueRequest(builder:flatbuffers.Builder, variantOffset:flatbuffers.Offset, multipleWordsPerTurn:boolean, vsAi:boolean):flatbuffers.Offset {
   EnqueueRequest.startEnqueueRequest(builder);
   EnqueueRequest.addVariant(builder, variantOffset);
   EnqueueRequest.addMultipleWordsPerTurn(builder, multipleWordsPerTurn);
+  EnqueueRequest.addVsAi(builder, vsAi);
   return EnqueueRequest.endEnqueueRequest(builder);
 }
 }

ui/src/gen/fbs/scrabblefb/game-view.ts

@@ -98,8 +98,13 @@ lastActivityUnix():bigint {
   return offset ? this.bb!.readInt64(this.bb_pos + offset) : BigInt('0');
 }
 
+vsAi():boolean {
+  const offset = this.bb!.__offset(this.bb_pos, 28);
+  return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : false;
+}
+
 static startGameView(builder:flatbuffers.Builder) {
-  builder.startObject(12);
+  builder.startObject(13);
 }
 
 static addId(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset) {
@@ -162,12 +167,16 @@ static addLastActivityUnix(builder:flatbuffers.Builder, lastActivityUnix:bigint)
   builder.addFieldInt64(11, lastActivityUnix, BigInt('0'));
 }
 
+static addVsAi(builder:flatbuffers.Builder, vsAi:boolean) {
+  builder.addFieldInt8(12, +vsAi, +false);
+}
+
 static endGameView(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;
 }
 
-static createGameView(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset, variantOffset:flatbuffers.Offset, dictVersionOffset:flatbuffers.Offset, statusOffset:flatbuffers.Offset, players:number, toMove:number, turnTimeoutSecs:number, multipleWordsPerTurn:boolean, moveCount:number, endReasonOffset:flatbuffers.Offset, seatsOffset:flatbuffers.Offset, lastActivityUnix:bigint):flatbuffers.Offset {
+static createGameView(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset, variantOffset:flatbuffers.Offset, dictVersionOffset:flatbuffers.Offset, statusOffset:flatbuffers.Offset, players:number, toMove:number, turnTimeoutSecs:number, multipleWordsPerTurn:boolean, moveCount:number, endReasonOffset:flatbuffers.Offset, seatsOffset:flatbuffers.Offset, lastActivityUnix:bigint, vsAi:boolean):flatbuffers.Offset {
   GameView.startGameView(builder);
   GameView.addId(builder, idOffset);
   GameView.addVariant(builder, variantOffset);
@@ -181,6 +190,7 @@ static createGameView(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset,
   GameView.addEndReason(builder, endReasonOffset);
   GameView.addSeats(builder, seatsOffset);
   GameView.addLastActivityUnix(builder, lastActivityUnix);
+  GameView.addVsAi(builder, vsAi);
   return GameView.endGameView(builder);
 }
 }

ui/src/lib/client.ts

@@ -68,7 +68,8 @@ export interface GatewayClient {
   gamesList(): Promise<GameList>;
 
   // --- lobby ---
-  lobbyEnqueue(variant: Variant, multipleWords: boolean): Promise<MatchResult>;
+  /** Start a quick game: human auto-match, or an honest-AI game against a robot when vsAi. */
+  lobbyEnqueue(variant: Variant, multipleWords: boolean, vsAi: boolean): Promise<MatchResult>;
   lobbyPoll(): Promise<MatchResult>;
   /** Leave the auto-match pool (idempotent); a cancelled quick-match must not stay queued. */
   lobbyCancel(): Promise<void>;

ui/src/lib/codec.test.ts

@@ -20,6 +20,7 @@ import {
   encodeCheckWord,
   encodeFeedbackSubmit,
   encodeDraftSave,
+  encodeEnqueue,
   encodeExchange,
   encodeStateRequest,
   encodeSubmitPlay,
@@ -27,6 +28,17 @@ import {
 } from './codec';
 
 describe('codec', () => {
+  it('encodes an enqueue request carrying the variant, word rule and vs_ai flag', () => {
+    for (const vsAi of [false, true]) {
+      const req = fb.EnqueueRequest.getRootAsEnqueueRequest(
+        new ByteBuffer(encodeEnqueue('scrabble_ru', false, vsAi)),
+      );
+      expect(req.variant()).toBe('scrabble_ru');
+      expect(req.multipleWordsPerTurn()).toBe(false);
+      expect(req.vsAi()).toBe(vsAi);
+    }
+  });
+
   it('round-trips a draft save request and view', () => {
     const json = '{"rack_order":"1,0","board_tiles":[]}';
     const req = fb.DraftRequest.getRootAsDraftRequest(new ByteBuffer(encodeDraftSave('g1', json)));
@@ -205,6 +217,7 @@ describe('codec', () => {
     fb.GameView.addEndReason(b, er);
     fb.GameView.addSeats(b, seats);
     fb.GameView.addLastActivityUnix(b, BigInt(1717000000));
+    fb.GameView.addVsAi(b, true);
     const game = fb.GameView.endGameView(b);
     const games = fb.GameList.createGamesVector(b, [game]);
     fb.GameList.startGameList(b);
@@ -217,6 +230,7 @@ describe('codec', () => {
     expect(gl.games[0].seats[0].displayName).toBe('Ann');
     expect(gl.games[0].seats[0].score).toBe(13);
     expect(gl.games[0].lastActivityUnix).toBe(1717000000);
+    expect(gl.games[0].vsAi).toBe(true);
   });
 
   it('decodes an OutgoingRequestList of account refs', () => {

ui/src/lib/codec.ts

@@ -151,12 +151,13 @@ export function encodeComplaint(gameId: string, word: string, note: string): Uin
   return finish(b, fb.ComplaintRequest.endComplaintRequest(b));
 }
 
-export function encodeEnqueue(variant: Variant, multipleWords: boolean): Uint8Array {
+export function encodeEnqueue(variant: Variant, multipleWords: boolean, vsAi: boolean): Uint8Array {
   const b = new Builder(64);
   const v = b.createString(variant);
   fb.EnqueueRequest.startEnqueueRequest(b);
   fb.EnqueueRequest.addVariant(b, v);
   fb.EnqueueRequest.addMultipleWordsPerTurn(b, multipleWords);
+  fb.EnqueueRequest.addVsAi(b, vsAi);
   return finish(b, fb.EnqueueRequest.endEnqueueRequest(b));
 }
 
@@ -244,6 +245,7 @@ function decodeGameView(g: fb.GameView): GameView {
     moveCount: g.moveCount(),
     endReason: s(g.endReason()),
     lastActivityUnix: Number(g.lastActivityUnix()),
+    vsAi: g.vsAi(),
     seats,
   };
 }
@@ -781,6 +783,7 @@ function emptyGame(): GameView {
     moveCount: 0,
     endReason: '',
     lastActivityUnix: 0,
+    vsAi: false,
     seats: [],
   };
 }

ui/src/lib/gamecache.test.ts

@@ -7,6 +7,7 @@ function gameView(id: string): GameView {
     id,
     variant: 'scrabble_en',
     dictVersion: 'v1',
+    vsAi: false,
     status: 'active',
     players: 2,
     toMove: 0,

ui/src/lib/gamedelta.test.ts

@@ -8,6 +8,7 @@ function gameView(moveCount: number, over = false): GameView {
     id: 'g1',
     variant: 'scrabble_en',
     dictVersion: 'v1',
+    vsAi: false,
     status: over ? 'finished' : 'active',
     players: 2,
     toMove: 1,

ui/src/lib/i18n/en.ts

@@ -44,7 +44,6 @@ export const en = {
   'lobby.vs': 'vs {opponents}',
 
   'new.title': 'New game',
-  'new.subtitle': 'Auto-match with another player',
   'new.english': 'Scrabble',
   'new.russian': 'Скрэббл',
   'new.erudit': 'Erudite',
@@ -265,6 +264,9 @@ export const en = {
   'new.start': 'Start game',
   'new.invited': 'Invitation sent.',
   'new.noFriends': 'Add friends first to invite them.',
+  'new.opponentAI': 'AI',
+  'new.opponentRandom': 'Random player',
+  'new.aiInactiveLimit': 'Loss after 7 days of inactivity',
 
   'stats.title': 'Statistics',
   'stats.wins': 'Wins',

ui/src/lib/i18n/ru.ts

@@ -45,7 +45,6 @@ export const ru: Record<MessageKey, string> = {
   'lobby.vs': 'против {opponents}',
 
   'new.title': 'Новая игра',
-  'new.subtitle': 'Автоподбор соперника',
   'new.english': 'Scrabble',
   'new.russian': 'Скрэббл',
   'new.erudit': 'Эрудит',
@@ -266,6 +265,9 @@ export const ru: Record<MessageKey, string> = {
   'new.start': 'Начать игру',
   'new.invited': 'Приглашение отправлено.',
   'new.noFriends': 'Сначала добавьте друзей, чтобы пригласить их.',
+  'new.opponentAI': 'ИИ',
+  'new.opponentRandom': 'Случайный игрок',
+  'new.aiInactiveLimit': 'Поражение, если 7 дней нет активности',
 
   'stats.title': 'Статистика',
   'stats.wins': 'Победы',

ui/src/lib/lobbycache.test.ts

@@ -24,6 +24,7 @@ function gameView(id: string, status: GameView['status'] = 'active', toMove = 0)
     id,
     variant: 'scrabble_en',
     dictVersion: 'v1',
+    vsAi: false,
     status,
     players: 2,
     toMove,

ui/src/lib/lobbysort.test.ts

@@ -17,6 +17,7 @@ function game(id: string, status: GameView['status'], toMove: number, lastActivi
     id,
     variant: 'scrabble_en',
     dictVersion: 'v1',
+    vsAi: false,
     status,
     players: 2,
     toMove,

ui/src/lib/mock/client.ts

@@ -156,11 +156,42 @@ export class MockGateway implements GatewayClient {
   }
 
   // --- lobby ---
-  async lobbyEnqueue(variant: Variant, multipleWords: boolean): Promise<MatchResult> {
+  async lobbyEnqueue(variant: Variant, multipleWords: boolean, vsAi: boolean): Promise<MatchResult> {
+    const id = crypto.randomUUID();
+    if (vsAi) {
+      // An honest-AI game starts active, already seated with a robot (rendered as 🤖 from the
+      // vs_ai flag); there is no open/wait phase.
+      const ai: MockGame = {
+        view: {
+          id,
+          variant,
+          dictVersion: 'v1',
+          status: 'active',
+          players: 2,
+          toMove: 0,
+          turnTimeoutSecs: 604800,
+          multipleWordsPerTurn: multipleWords,
+          moveCount: 0,
+          endReason: '',
+          lastActivityUnix: Math.floor(Date.now() / 1000),
+          vsAi: true,
+          seats: [
+            { seat: 0, accountId: ME, displayName: 'You', score: 0, hintsUsed: 0, isWinner: false },
+            { seat: 1, accountId: 'robot', displayName: 'Robot', score: 0, hintsUsed: 0, isWinner: false },
+          ],
+        },
+        moves: [],
+        rack: draw(variant, 7),
+        bagLen: 86,
+        hintsRemaining: 1,
+        chat: [],
+      };
+      this.games.set(id, ai);
+      return { matched: true, game: structuredClone(ai.view) };
+    }
     // The player enters an open game immediately and waits inside it; a robot opponent takes
     // the empty seat shortly (a sped-up version of the backend's 90–180 s wait), pushing
     // opponent_joined so the game UI restores from the "searching for opponent" state.
-    const id = crypto.randomUUID();
     const g: MockGame = {
       view: {
         id,
@@ -174,6 +205,7 @@ export class MockGateway implements GatewayClient {
         moveCount: 0,
         endReason: '',
         lastActivityUnix: Math.floor(Date.now() / 1000),
+        vsAi: false,
         seats: [
           { seat: 0, accountId: ME, displayName: 'You', score: 0, hintsUsed: 0, isWinner: false },
           { seat: 1, accountId: '', displayName: '', score: 0, hintsUsed: 0, isWinner: false },

ui/src/lib/mock/data.ts

@@ -139,6 +139,7 @@ function activeGame(): MockGame {
       id: 'g1',
       variant: 'scrabble_en',
       dictVersion: 'v1',
+      vsAi: false,
       status: 'active',
       players: 2,
       toMove: 0,
@@ -174,6 +175,7 @@ function finishedG2(): MockGame {
       id: 'g2',
       variant: 'scrabble_en',
       dictVersion: 'v1',
+      vsAi: false,
       status: 'finished',
       players: 2,
       toMove: 0,
@@ -210,6 +212,7 @@ function finishedG3(): MockGame {
       id: 'g3',
       variant: 'scrabble_ru',
       dictVersion: 'v1',
+      vsAi: false,
       status: 'finished',
       players: 2,
       toMove: 0,

ui/src/lib/model.ts

@@ -45,6 +45,8 @@ export interface GameView {
   endReason: string;
   /** Lobby sort key: the current turn's start (active) or the finish time (finished), Unix seconds. */
   lastActivityUnix: number;
+  /** true = an honest-AI game: the opponent is shown as 🤖 and chat/nudge/add-friend are disabled. */
+  vsAi: boolean;
   seats: Seat[];
 }
 

ui/src/lib/preload.test.ts

@@ -19,6 +19,7 @@ function gameView(id: string, status: GameView['status'] = 'active'): GameView {
     id,
     variant: 'scrabble_en',
     dictVersion: 'v1',
+    vsAi: false,
     status,
     players: 2,
     toMove: 0,

ui/src/lib/result.test.ts

@@ -16,6 +16,7 @@ function game(seats: Seat[], status = 'finished', toMove = 0): GameView {
     id: 'g',
     variant: 'scrabble_en',
     dictVersion: 'v1',
+    vsAi: false,
     status,
     players: seats.length,
     toMove,

ui/src/lib/transport.ts

@@ -84,8 +84,8 @@ export function createTransport(baseUrl: string): GatewayClient {
       return codec.decodeGameList(await exec('games.list', codec.empty()));
     },
 
-    async lobbyEnqueue(variant, multipleWords) {
-      return codec.decodeMatchResult(await exec('lobby.enqueue', codec.encodeEnqueue(variant, multipleWords)));
+    async lobbyEnqueue(variant, multipleWords, vsAi) {
+      return codec.decodeMatchResult(await exec('lobby.enqueue', codec.encodeEnqueue(variant, multipleWords, vsAi)));
     },
     async lobbyPoll() {
       return codec.decodeMatchResult(await exec('lobby.poll', codec.empty()));

ui/src/screens/Lobby.svelte

@@ -63,6 +63,8 @@
   function opponents(g: GameView): string {
     // An auto-match game still waiting for an opponent shows the "searching" placeholder.
     if (g.status === 'open') return t('game.searchingForOpponent');
+    // An honest-AI game shows the robot opponent as 🤖, never its (pooled) name.
+    if (g.vsAi) return '🤖';
     return g.seats
       .filter((s) => s.accountId !== myId)
       .map((s) => s.displayName)

ui/src/screens/NewGame.svelte

@@ -39,6 +39,9 @@
 
   const guest = $derived(app.profile?.isGuest ?? true);
   let mode = $state<'auto' | 'friends'>('auto');
+  // The quick-game opponent: an honest AI (a robot that joins and moves at once, shown as 🤖)
+  // or a random human via auto-match. AI is the default.
+  let opponent = $state<'ai' | 'random'>('ai');
 
   // --- auto-match ---
   // Enqueue drops the player straight into a real game — a freshly opened one awaiting an
@@ -51,7 +54,7 @@
     if (starting) return;
     starting = true;
     try {
-      const r = await gateway.lobbyEnqueue(v, multipleWordsForRequest(v, multipleWords));
+      const r = await gateway.lobbyEnqueue(v, multipleWordsForRequest(v, multipleWords), opponent === 'ai');
       if (r.game) navigate(`/game/${r.game.id}`);
     } catch (e) {
       handleError(e);
@@ -119,7 +122,10 @@
       {/if}
 
       {#if mode === 'auto'}
-        <p class="subtitle">{t('new.subtitle')}</p>
+        <div class="seg modes">
+          <button class="opt" class:active={opponent === 'ai'} onclick={() => (opponent = 'ai')}>🤖 {t('new.opponentAI')}</button>
+          <button class="opt" class:active={opponent === 'random'} onclick={() => (opponent = 'random')}>👤 {t('new.opponentRandom')}</button>
+        </div>
         <div class="variants">
           {#each variants as v (v.id)}
             <button
@@ -146,8 +152,8 @@
             <input type="checkbox" bind:checked={multipleWords} />
           </label>
         {/if}
-        <p class="movelimit">{t('new.moveLimit', { n: AUTO_MATCH_HOURS })}</p>
-        <p class="searchhint">{t('new.searchHint')}</p>
+        <p class="movelimit">{opponent === 'ai' ? t('new.aiInactiveLimit') : t('new.moveLimit', { n: AUTO_MATCH_HOURS })}</p>
+        {#if opponent === 'random'}<p class="searchhint">{t('new.searchHint')}</p>{/if}
         <button
           class="invite"
           disabled={!selectedAuto || !connection.online || starting}