feat: blindtest needs 2 real players + bot difficulty setting

- blindtest is only available with >=3 players AND >=2 humans (a bot can't be DJ):
  lobby gate + tooltips updated, and server game:start rejects otherwise
- new botDifficulty setting (easy/normal/hard) drives how often bots answer
  correctly (quiz + blindtest who-added / title-artist); host picks it in the
  lobby when at least one bot is present

Verified e2e: blindtest start rejected with 1 human + 2 bots (NEED_THREE).

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

apps/server/src/game/bot.ts

@@ -0,0 +1,13 @@
+// Réglage de difficulté des bots : probabilité de donner la bonne réponse.
+
+import type { BotDifficulty } from "@nerdware/shared"
+
+const CHANCE: Record<BotDifficulty, number> = {
+  easy: 0.3,
+  normal: 0.55,
+  hard: 0.85,
+}
+
+export function botCorrectChance(difficulty: BotDifficulty): number {
+  return CHANCE[difficulty] ?? CHANCE.normal
+}

apps/server/src/game/modes/blindtest/blindtest-round.ts

@@ -19,6 +19,7 @@ import type {
 } from "../../round"
 import type { BlindtestTrack, ServerRoom } from "../../../rooms"
 import { fuzzyMatch } from "../../match"
+import { botCorrectChance } from "../../bot"
 import { takeTrack } from "./pool"
 
 const TITLE_POINTS = 60
@@ -101,16 +102,19 @@ export class BlindtestRound implements GameRound {
   botAnswer(ctx: RoundContext, playerId: string): Answer {
     const { track } = ctx.data as BlindtestRoundData
     const mode = ctx.room.settings.blindtestMode
-    // Devine un joueur au hasard (parfois le bon contributeur).
+    const chance = botCorrectChance(ctx.room.settings.botDifficulty)
+    // Selon le niveau : devine le bon contributeur, sinon un joueur au hasard.
     const others = [...ctx.room.players.values()]
       .filter((p) => p.id !== playerId)
       .map((p) => p.id)
     const guessedPlayerId =
-      others[Math.floor(Math.random() * others.length)] ?? playerId
+      Math.random() < chance
+        ? track.submittedBy
+        : (others[Math.floor(Math.random() * others.length)] ?? playerId)
     if (mode === "who_added") {
       return { guessedPlayerId }
     }
-    const right = Math.random() < 0.4
+    const right = Math.random() < chance
     const title = right ? track.title : "?"
     const artist = right ? track.artist : "?"
     if (mode === "title_artist") {

apps/server/src/game/modes/quiz/quiz-round.ts

@@ -9,6 +9,7 @@ import type {
   ScoreDelta,
 } from "@nerdware/shared"
 import { hasDb } from "../../../db"
+import { botCorrectChance } from "../../bot"
 import { markQuestionPlayed } from "../../../db/quiz-repo"
 import { fuzzyMatch } from "../../match"
 import type {
@@ -149,8 +150,8 @@ export class QuizRound implements GameRound {
 
   botAnswer(ctx: RoundContext): Answer {
     const { question } = ctx.data as QuizRoundData
-    // ~50% du temps le bot répond juste, sinon une réponse plausible mais fausse.
-    const rightish = Math.random() < 0.5
+    // Le bot répond juste selon le niveau choisi, sinon une réponse plausible.
+    const rightish = Math.random() < botCorrectChance(ctx.room.settings.botDifficulty)
     if (isTextFormat(question)) {
       return {
         text: rightish ? (question.acceptedAnswers?.[0] ?? "?") : "euh…",

apps/server/src/handlers.ts

@@ -144,6 +144,7 @@ export function registerRoomHandlers(
       roundDuration: payload.roundDuration,
       tracksPerPlayer: payload.tracksPerPlayer,
       categories: payload.categories,
+      botDifficulty: payload.botDifficulty,
       rounds: payload.rounds,
     }
     broadcastState(room)
@@ -194,15 +195,17 @@ export function registerRoomHandlers(
       return
     }
     const hasBlindtest = room.settings.rounds.some((r) => r.type === "blindtest")
-    const connected = [...room.players.values()].filter(
+    const active = [...room.players.values()].filter(
       (p) => p.connected && p.name !== ""
-    ).length
-    if (hasBlindtest && connected < 3) {
+    )
+    const connected = active.length
+    const humans = active.filter((p) => !p.isBot).length
+    if (hasBlindtest && (connected < 3 || humans < 2)) {
       ack({
         ok: false,
         error: {
           code: "NEED_THREE",
-          message: "Le blindtest nécessite au moins 3 joueurs.",
+          message: "Le blindtest nécessite au moins 3 joueurs dont 2 réels.",
         },
       })
       return

apps/web/src/components/lobby-view.tsx

@@ -51,6 +51,12 @@ const MODE_LABELS: Record<BlindtestMode, string> = {
   who_added: "Qui l'a ajouté ?",
   mixed: "Mixte",
 }
+const BOT_DIFFICULTIES = ["easy", "normal", "hard"] as const
+const BOT_DIFF_LABELS: Record<(typeof BOT_DIFFICULTIES)[number], string> = {
+  easy: "Facile",
+  normal: "Normal",
+  hard: "Difficile",
+}
 
 const inputClass =
   "border-input bg-background h-10 w-full rounded-md border px-3 py-2 text-sm focus-visible:ring-ring focus-visible:ring-2 focus-visible:outline-none disabled:opacity-50"
@@ -140,8 +146,14 @@ export function LobbyView({ snapshot }: { snapshot: RoomSnapshot }) {
   const removeBot = useRoomStore((s) => s.removeBot)
   const isHost = snapshot.hostId === playerId
   const botCount = snapshot.players.filter((p) => p.bot).length
-  const { gameType, mixedModes, blindtestMode, tracksPerPlayer, categories } =
-    snapshot.settings
+  const {
+    gameType,
+    mixedModes,
+    blindtestMode,
+    tracksPerPlayer,
+    categories,
+    botDifficulty,
+  } = snapshot.settings
   const allCategories =
     useQuery({ queryKey: ["categories"], queryFn: fetchCategories }).data ?? []
   const history =
@@ -159,9 +171,13 @@ export function LobbyView({ snapshot }: { snapshot: RoomSnapshot }) {
   const myCount =
     snapshot.submissions.find((s) => s.playerId === playerId)?.count ?? 0
 
-  // Le blindtest exige au moins 3 joueurs connectés (DJ + 2 devineurs).
+  // Le blindtest exige 3 joueurs (DJ + 2 devineurs) DONT au moins 2 réels :
+  // un bot ne peut pas être DJ, donc il faut un humain DJ + un humain contributeur.
   const connectedCount = snapshot.players.filter((p) => p.connected).length
-  const blindtestAvailable = connectedCount >= 3
+  const humanCount = snapshot.players.filter(
+    (p) => p.connected && !p.bot
+  ).length
+  const blindtestAvailable = connectedCount >= 3 && humanCount >= 2
   // Seul le blindtest "seul" retombe sur du quiz à <3 ; le mixte reste mixte
   // (son sous-mode blindtest est juste désactivé tant qu'on n'est pas 3).
   const effectiveType: GameType =
@@ -297,7 +313,7 @@ export function LobbyView({ snapshot }: { snapshot: RoomSnapshot }) {
                   <button
                     key={value}
                     disabled={locked}
-                    title={locked ? "3 joueurs minimum" : undefined}
+                    title={locked ? "3 joueurs dont 2 réels" : undefined}
                     onClick={() => updateSettings({ gameType: value })}
                     className={`flex flex-col items-center gap-1.5 rounded-lg border p-2.5 text-xs font-medium transition-colors disabled:opacity-40 ${
                       active
@@ -313,7 +329,8 @@ export function LobbyView({ snapshot }: { snapshot: RoomSnapshot }) {
             </div>
             {!blindtestAvailable && (
               <p className="text-muted-foreground text-xs">
-                Le blindtest se débloque à 3 joueurs.
+                Le blindtest se débloque à 3 joueurs dont 2 réels (un bot ne peut
+                pas être DJ).
               </p>
             )}
           </div>
@@ -330,7 +347,7 @@ export function LobbyView({ snapshot }: { snapshot: RoomSnapshot }) {
                     <button
                       key={m}
                       disabled={locked}
-                      title={locked ? "3 joueurs minimum" : undefined}
+                      title={locked ? "3 joueurs dont 2 réels" : undefined}
                       onClick={() => toggleMix(m)}
                       className={`flex-1 rounded-lg border px-2 py-1.5 text-xs font-medium transition-colors disabled:opacity-40 ${
                         on
@@ -410,6 +427,26 @@ export function LobbyView({ snapshot }: { snapshot: RoomSnapshot }) {
             </div>
           )}
 
+          {/* Niveau des bots (si au moins un bot dans la partie) */}
+          {botCount > 0 && (
+            <div className="flex flex-col gap-1.5">
+              <span className="text-sm font-medium">🤖 Niveau des bots</span>
+              <div className="flex gap-1">
+                {BOT_DIFFICULTIES.map((d) => (
+                  <Button
+                    key={d}
+                    size="sm"
+                    className="flex-1"
+                    variant={botDifficulty === d ? "default" : "secondary"}
+                    onClick={() => updateSettings({ botDifficulty: d })}
+                  >
+                    {BOT_DIFF_LABELS[d]}
+                  </Button>
+                ))}
+              </div>
+            </div>
+          )}
+
           {/* Réglages blindtest */}
           {showBlindtest && (
             <div className="flex flex-col gap-3 border-t pt-3">

apps/web/src/store/room.ts

@@ -164,6 +164,7 @@ export const useRoomStore = create<RoomState>((set, get) => ({
       roundDuration: partial.roundDuration ?? current.roundDuration,
       tracksPerPlayer: partial.tracksPerPlayer ?? current.tracksPerPlayer,
       categories: partial.categories ?? current.categories,
+      botDifficulty: partial.botDifficulty ?? current.botDifficulty,
       rounds: partial.rounds ?? current.rounds,
     })
   },

packages/shared/src/domain.ts

@@ -16,6 +16,9 @@ export type MixMode = "quiz" | "image" | "blindtest"
 /** Modes de blindtest, déterminent la forme du vote et le barème. */
 export type BlindtestMode = "title_artist" | "who_added" | "mixed"
 
+/** Niveau des bots : pilote leur probabilité de répondre juste. */
+export type BotDifficulty = "easy" | "normal" | "hard"
+
 /** Formats de question quiz. */
 export type QuizFormat = "mcq" | "truefalse" | "free" | "image_reveal"
 
@@ -48,6 +51,8 @@ export interface RoomSettings {
   tracksPerPlayer: number
   /** Catégories de quiz autorisées (vide = toutes). */
   categories: string[]
+  /** Niveau des bots ajoutés à la partie. */
+  botDifficulty: BotDifficulty
   /** Séquence d'épreuves de la partie. */
   rounds: RoundConfig[]
 }
@@ -60,6 +65,7 @@ export const DEFAULT_ROOM_SETTINGS: RoomSettings = {
   roundDuration: 60,
   tracksPerPlayer: 2,
   categories: [],
+  botDifficulty: "normal",
   rounds: [],
 }
 

packages/shared/src/events.ts

@@ -4,6 +4,7 @@
 import type {
   Answer,
   BlindtestMode,
+  BotDifficulty,
   GameType,
   MixMode,
   PlayerScore,
@@ -49,6 +50,7 @@ export interface UpdateSettingsPayload {
   roundDuration: number
   tracksPerPlayer: number
   categories: string[]
+  botDifficulty: BotDifficulty
   rounds: RoundConfig[]
 }