fix(site): repair onboarding audio cleanup, redirect, and manifest fetches

- loadDialogueManifest: cache the resolved manifest at module level and
  dedupe concurrent fetches so each screen no longer re-downloads it
- useGameStore: completeIntroState now also advances intro.currentStep
  to "playing" so callers do not need a separate setIntroStep call
- SiteNamingScreen and SiteTransitionOverlay: replace ref-based guards
  with an isCancelled flag captured per effect. The previous guards
  persisted across StrictMode remounts, leaving mount 2 unable to
  re-run the effect after mount 1's chain was cancelled, which broke
  the fade animations, the second narrator dialogue and the redirect.
  Both screens now also call stopCurrentDialogue on unmount so audio
  cannot bleed across routes, and the transition gets a safety timeout
  in case the dialogue audio fails to fire its "ended" event
- SiteTransitionOverlay: keep the <Subtitles /> mount inside the
  overlay so it renders inside the z-index 1000 stacking context
  (above the black screen); the one in SiteLayout sits behind it
- IntroDialogueOverlay: route through playDialogueById instead of
  AudioManager.playSoundWithCallback so the narrator subtitles play
  in sync, and add the same isCancelled cleanup pattern
- IntroRevealOverlay: rely on completeIntro alone now that it advances
  intro.currentStep, and skip the fade when reduced motion is requested
- SiteMobileBlocker: correct logo path from public/... to /...

src/components/site/SiteMobileBlocker.tsx

@@ -1,37 +1,28 @@
-import { SITE_CONFIG } from "@/data/site/siteConfig";
+import { SITE_BACKGROUND_STYLE } from "@/data/site/siteConfig";
 
 const MOBILE_TEXT =
   "Ce site a été conçu pour être utilisé sur ordinateur. Veuillez réessayer sur votre ordinateur pour une expérience optimale.";
 
-/**
- * Mobile blocker screen
- */
 export function SiteMobileBlocker(): React.JSX.Element {
   return (
     <div
+      role="alert"
       style={{
         position: "fixed",
         inset: 0,
-        backgroundColor: "#87CEEB",
-        backgroundImage: `url(${SITE_CONFIG.backgroundImage})`,
-        backgroundSize: "cover",
-        backgroundPosition: "center",
-        backgroundRepeat: "no-repeat",
         display: "flex",
         flexDirection: "column",
         alignItems: "center",
         justifyContent: "center",
         padding: 32,
         gap: 48,
+        ...SITE_BACKGROUND_STYLE,
       }}
     >
       <img
-        src="public/assets/logo/logo.jpg"
-        alt="Logo"
-        style={{
-          width: 120,
-          height: "auto",
-        }}
+        src="/assets/logo/logo.jpg"
+        alt="Logo Altera"
+        style={{ width: 120, height: "auto" }}
       />
       <p
         style={{

src/components/site/SiteNamingScreen.tsx

@@ -3,52 +3,61 @@ import { useGameStore } from "@/managers/stores/useGameStore";
 import { useSiteStore } from "@/managers/stores/useSiteStore";
 import { SiteButton } from "@/components/site/SiteButton";
 import { SITE_CONFIG } from "@/data/site/siteConfig";
+import { SITE_DIALOGUE_IDS } from "@/data/site/dialogueIds";
 import { loadDialogueManifest } from "@/utils/dialogues/loadDialogueManifest";
-import { playDialogueById } from "@/utils/dialogues/playDialogue";
+import {
+  playDialogueById,
+  stopCurrentDialogue,
+} from "@/utils/dialogues/playDialogue";
 
 /**
  * Screen 3: Name input
+ * The displayed name is forced to SITE_CONFIG.presetPlayerName — the
+ * field reveals one letter per keystroke until the preset name is complete.
  */
 export function SiteNamingScreen(): React.JSX.Element {
   const setStep = useSiteStore((state) => state.setStep);
   const setPlayerName = useGameStore((state) => state.setPlayerName);
   const [charIndex, setCharIndex] = useState(0);
-  const dialogueStarted = useRef(false);
   const inputRef = useRef<HTMLInputElement>(null);
 
-  const forcedName = SITE_CONFIG.forcedName;
-  const displayValue = forcedName.slice(0, charIndex);
-  const isComplete = charIndex >= forcedName.length;
+  const presetPlayerName = SITE_CONFIG.presetPlayerName;
+  const displayValue = presetPlayerName.slice(0, charIndex);
+  const isComplete = charIndex >= presetPlayerName.length;
 
-  // Play dialogue when screen appears (with subtitles)
   useEffect(() => {
-    if (dialogueStarted.current) return;
-    dialogueStarted.current = true;
+    let cancelled = false;
 
     void (async () => {
       const manifest = await loadDialogueManifest();
-      if (manifest) {
-        await playDialogueById(manifest, "narrateur_intro_prenom");
-      }
+      if (cancelled || !manifest) return;
+      await playDialogueById(manifest, SITE_DIALOGUE_IDS.naming);
     })();
+
+    return () => {
+      cancelled = true;
+      stopCurrentDialogue();
+    };
   }, []);
 
-  // Focus input on mount
   useEffect(() => {
     inputRef.current?.focus();
   }, []);
 
   const handleNameChange = useCallback(
     (event: React.ChangeEvent<HTMLInputElement>): void => {
-      const nextLength = Math.min(event.target.value.length, forcedName.length);
+      const nextLength = Math.min(
+        event.target.value.length,
+        presetPlayerName.length,
+      );
       setCharIndex(nextLength);
     },
-    [forcedName.length],
+    [presetPlayerName.length],
   );
 
   const handleConfirm = (): void => {
     if (isComplete) {
-      setPlayerName(forcedName);
+      setPlayerName(presetPlayerName);
       setStep("transition");
     }
   };
@@ -75,6 +84,7 @@ export function SiteNamingScreen(): React.JSX.Element {
         }}
       >
         <h2
+          id="player-name-label"
           style={{
             color: "#F2F2F2",
             textAlign: "center",
@@ -97,6 +107,9 @@ export function SiteNamingScreen(): React.JSX.Element {
           value={displayValue}
           onChange={handleNameChange}
           placeholder="Écrivez votre prénom ici"
+          aria-labelledby="player-name-label"
+          aria-describedby="player-name-hint"
+          autoComplete="off"
           style={{
             display: "flex",
             padding: "clamp(8px, 1.5vw, 10px)",
@@ -116,6 +129,23 @@ export function SiteNamingScreen(): React.JSX.Element {
             boxSizing: "border-box",
           }}
         />
+        <span
+          id="player-name-hint"
+          style={{
+            position: "absolute",
+            width: 1,
+            height: 1,
+            padding: 0,
+            margin: -1,
+            overflow: "hidden",
+            clip: "rect(0, 0, 0, 0)",
+            whiteSpace: "nowrap",
+            border: 0,
+          }}
+        >
+          Votre personnage s&apos;appelle {presetPlayerName}. Tapez{" "}
+          {presetPlayerName.length} caractères pour révéler son nom.
+        </span>
       </div>
 
       <SiteButton

src/components/site/SiteTransitionOverlay.tsx

@@ -1,72 +1,102 @@
-import { useEffect, useRef, useState } from "react";
+import { useEffect, useState } from "react";
 import { useNavigate } from "@tanstack/react-router";
 import { useSiteStore } from "@/managers/stores/useSiteStore";
 import { Subtitles } from "@/components/ui/Subtitles";
 import { setSiteVisited } from "@/utils/cookies/siteVisitCookie";
 import { loadDialogueManifest } from "@/utils/dialogues/loadDialogueManifest";
-import { playDialogueById } from "@/utils/dialogues/playDialogue";
+import {
+  playDialogueById,
+  stopCurrentDialogue,
+} from "@/utils/dialogues/playDialogue";
+import { SITE_DIALOGUE_IDS } from "@/data/site/dialogueIds";
+import { usePrefersReducedMotion } from "@/hooks/ui/usePrefersReducedMotion";
 
 const FADE_DURATION_MS = 1000;
+const DIALOGUE_FALLBACK_TIMEOUT_MS = 12000;
+const NO_DIALOGUE_FALLBACK_MS = 3000;
 
 /**
- * Transition overlay: black screen (fade in) + logo (fade in/out) + dialogue with subtitles + redirect to /
+ * Transition overlay: black screen, logo fade-in, transition dialogue
+ * with subtitles, then redirect to /. A safety timeout guarantees the
+ * redirect happens even if the dialogue audio fails to fire `ended`.
  */
 export function SiteTransitionOverlay(): React.JSX.Element {
   const navigate = useNavigate();
   const reset = useSiteStore((state) => state.reset);
+  const prefersReducedMotion = usePrefersReducedMotion();
   const [screenOpacity, setScreenOpacity] = useState(0);
   const [logoOpacity, setLogoOpacity] = useState(0);
-  const transitionStarted = useRef(false);
 
   useEffect(() => {
-    if (transitionStarted.current) return;
-    transitionStarted.current = true;
-
-    // Fade in black screen
-    setScreenOpacity(1);
-
-    // Set cookie
     setSiteVisited();
 
-    // Fade in logo after the black screen transition delay.
-    setLogoOpacity(1);
+    let isCancelled = false;
+    const timeoutIds: number[] = [];
 
-    // Play transition dialogue (with subtitles) then fade out logo and redirect
-    void (async () => {
-      const manifest = await loadDialogueManifest();
-      if (manifest) {
-        const dialogueAudio = await playDialogueById(
-          manifest,
-          "narrateur_intro_apresprenom",
-        );
-        if (dialogueAudio) {
-          dialogueAudio.addEventListener(
-            "ended",
-            () => {
-              // Fade out logo
+    // Defer the opacity flip one tick so the CSS transition has an
+    // initial frame at opacity 0 before flipping to 1.
+    const fadeInId = window.setTimeout(() => {
+      setScreenOpacity(1);
+      setLogoOpacity(1);
+    }, 0);
+    timeoutIds.push(fadeInId);
+
+    const redirectToGame = (): void => {
+      if (isCancelled) return;
       setLogoOpacity(0);
-              // Redirect after logo fade out
-              setTimeout(() => {
+      const id = window.setTimeout(() => {
+        if (isCancelled) return;
         reset();
         navigate({ to: "/" });
       }, FADE_DURATION_MS);
+      timeoutIds.push(id);
+    };
+
+    void (async () => {
+      const manifest = await loadDialogueManifest();
+      if (isCancelled) return;
+
+      const dialogueAudio = manifest
+        ? await playDialogueById(manifest, SITE_DIALOGUE_IDS.transition)
+        : null;
+      if (isCancelled) return;
+
+      if (dialogueAudio) {
+        const safetyId = window.setTimeout(
+          redirectToGame,
+          DIALOGUE_FALLBACK_TIMEOUT_MS,
+        );
+        timeoutIds.push(safetyId);
+
+        dialogueAudio.addEventListener(
+          "ended",
+          () => {
+            window.clearTimeout(safetyId);
+            redirectToGame();
           },
           { once: true },
         );
         return;
       }
-      }
-      // Fallback: redirect after 3s if dialogue fails
-      setTimeout(() => {
-        setLogoOpacity(0);
-        setTimeout(() => {
-          reset();
-          navigate({ to: "/" });
-        }, FADE_DURATION_MS);
-      }, 3000);
+
+      const fallbackId = window.setTimeout(
+        redirectToGame,
+        NO_DIALOGUE_FALLBACK_MS,
+      );
+      timeoutIds.push(fallbackId);
     })();
+
+    return () => {
+      isCancelled = true;
+      timeoutIds.forEach(window.clearTimeout);
+      stopCurrentDialogue();
+    };
   }, [navigate, reset]);
 
+  const fadeTransition = prefersReducedMotion
+    ? "none"
+    : `opacity ${FADE_DURATION_MS}ms ease-in-out`;
+
   return (
     <div
       style={{
@@ -86,12 +116,12 @@ export function SiteTransitionOverlay(): React.JSX.Element {
           background: "#000",
           zIndex: 0,
           opacity: screenOpacity,
-          transition: `opacity ${FADE_DURATION_MS}ms ease-in-out`,
+          transition: fadeTransition,
         }}
       />
       <img
         src="/assets/logo/logo.jpg"
-        alt="Logo"
+        alt="Logo Altera"
         style={{
           position: "relative",
           zIndex: 1,
@@ -99,10 +129,16 @@ export function SiteTransitionOverlay(): React.JSX.Element {
           height: "auto",
           objectFit: "contain",
           opacity: logoOpacity,
-          transition: `opacity ${FADE_DURATION_MS}ms ease-in-out`,
-          transitionDelay: logoOpacity === 1 ? `${FADE_DURATION_MS}ms` : "0ms",
+          transition: fadeTransition,
+          transitionDelay:
+            !prefersReducedMotion && logoOpacity === 1
+              ? `${FADE_DURATION_MS}ms`
+              : "0ms",
         }}
       />
+      {/* Subtitles must live inside this overlay's stacking context
+          (z-index 1000) so they render above the black screen. The
+          <Subtitles /> in SiteLayout sits behind this overlay. */}
       <Subtitles />
     </div>
   );

src/components/ui/intro/IntroDialogueOverlay.tsx

@@ -1,31 +1,63 @@
-import { useEffect, useRef } from "react";
-import { AudioManager } from "@/managers/AudioManager";
+import { useEffect } from "react";
 import { useGameStore } from "@/managers/stores/useGameStore";
+import { SITE_DIALOGUE_IDS } from "@/data/site/dialogueIds";
+import { loadDialogueManifest } from "@/utils/dialogues/loadDialogueManifest";
+import {
+  playDialogueById,
+  stopCurrentDialogue,
+} from "@/utils/dialogues/playDialogue";
 
-const INTRO_DIALOGUE_PATH = "/sounds/dialogue/narrateur_ordreebike.mp3";
+const DIALOGUE_FALLBACK_TIMEOUT_MS = 12000;
 
 /**
- * Black screen overlay with dialogue audio
- * - Plays narrateur_ordreebike.mp3
- * - Transitions to reveal step when dialogue ends
+ * Black screen overlay that plays the intro dialogue (with synced subtitles)
+ * via the dialogue manifest, then transitions to the reveal step.
  */
 export function IntroDialogueOverlay(): React.JSX.Element {
   const setIntroStep = useGameStore((state) => state.setIntroStep);
-  const dialogueStarted = useRef(false);
 
   useEffect(() => {
-    if (dialogueStarted.current) return;
-    dialogueStarted.current = true;
+    let cancelled = false;
+    let safetyTimeoutId: number | null = null;
 
-    // Play dialogue then transition to reveal
-    const audio = AudioManager.getInstance();
-    audio.playSoundWithCallback(INTRO_DIALOGUE_PATH, 0.8, () => {
+    const advance = (): void => {
+      if (cancelled) return;
+      if (safetyTimeoutId !== null) window.clearTimeout(safetyTimeoutId);
       setIntroStep("reveal");
-    });
+    };
+
+    void (async () => {
+      const manifest = await loadDialogueManifest();
+      if (cancelled) return;
+
+      const audio = manifest
+        ? await playDialogueById(manifest, SITE_DIALOGUE_IDS.introOrder)
+        : null;
+      if (cancelled) return;
+
+      if (!audio) {
+        advance();
+        return;
+      }
+
+      safetyTimeoutId = window.setTimeout(
+        advance,
+        DIALOGUE_FALLBACK_TIMEOUT_MS,
+      );
+      audio.addEventListener("ended", advance, { once: true });
+    })();
+
+    return () => {
+      cancelled = true;
+      if (safetyTimeoutId !== null) window.clearTimeout(safetyTimeoutId);
+      stopCurrentDialogue();
+    };
   }, [setIntroStep]);
 
   return (
     <div
+      role="region"
+      aria-label="Dialogue d'introduction"
       style={{
         position: "fixed",
         inset: 0,
@@ -37,6 +69,7 @@ export function IntroDialogueOverlay(): React.JSX.Element {
       }}
     >
       <span
+        aria-hidden="true"
         style={{
           color: "rgba(255, 255, 255, 0.5)",
           fontSize: 16,

src/components/ui/intro/IntroRevealOverlay.tsx

@@ -1,28 +1,25 @@
 import { useEffect, useState } from "react";
 import { useGameStore } from "@/managers/stores/useGameStore";
+import { usePrefersReducedMotion } from "@/hooks/ui/usePrefersReducedMotion";
 
 const REVEAL_DURATION_MS = 2000;
 
 /**
- * Fade-out overlay for reveal transition
- * - Starts fully black
- * - Fades out to reveal the game world
- * - Transitions to playing step when done
+ * Fade-out overlay revealing the game world.
+ * Calls completeIntro() when the fade is done — completeIntro also flips
+ * intro.currentStep to "playing" so no separate setIntroStep call is needed.
  */
 export function IntroRevealOverlay(): React.JSX.Element {
-  const setIntroStep = useGameStore((state) => state.setIntroStep);
   const completeIntro = useGameStore((state) => state.completeIntro);
+  const prefersReducedMotion = usePrefersReducedMotion();
   const [opacity, setOpacity] = useState(1);
 
   useEffect(() => {
-    // Start fade out
     const fadeTimeout = window.setTimeout(() => {
       setOpacity(0);
     }, 100);
 
-    // Complete intro after fade
     const completeTimeout = window.setTimeout(() => {
-      setIntroStep("playing");
       completeIntro();
     }, REVEAL_DURATION_MS);
 
@@ -30,16 +27,19 @@ export function IntroRevealOverlay(): React.JSX.Element {
       window.clearTimeout(fadeTimeout);
       window.clearTimeout(completeTimeout);
     };
-  }, [setIntroStep, completeIntro]);
+  }, [completeIntro]);
 
   return (
     <div
+      aria-hidden="true"
       style={{
         position: "fixed",
         inset: 0,
         background: "#000",
         opacity,
-        transition: `opacity ${REVEAL_DURATION_MS}ms ease-out`,
+        transition: prefersReducedMotion
+          ? "none"
+          : `opacity ${REVEAL_DURATION_MS}ms ease-out`,
         zIndex: 998,
         pointerEvents: "none",
       }}

src/managers/stores/useGameStore.ts

@@ -121,6 +121,7 @@ function completeIntroState(state: GameState): GameStateUpdate {
     mainState: "ebike",
     intro: {
       ...state.intro,
+      currentStep: "playing",
       hasCompleted: true,
       isEbikeUnlocked: true,
     },

src/utils/dialogues/loadDialogueManifest.ts

@@ -12,6 +12,9 @@ import type { SubtitleCue } from "@/utils/subtitles/parseSrt";
 const DIALOGUE_MANIFEST_PATH = "/sounds/dialogue/dialogues.json";
 const DEFAULT_SUBTITLE_LANGUAGE: SubtitleLanguage = "fr";
 
+let manifestCache: DialogueManifest | null = null;
+let manifestPromise: Promise<DialogueManifest | null> | null = null;
+
 export interface DialogueSubtitleCue {
   voice: DialogueVoice;
   cue: SubtitleCue;
@@ -28,13 +31,21 @@ export interface DialogueSubtitleCues {
 }
 
 export async function loadDialogueManifest(): Promise<DialogueManifest | null> {
-  const response = await fetch(DIALOGUE_MANIFEST_PATH);
+  if (manifestCache) return manifestCache;
+  if (manifestPromise) return manifestPromise;
 
+  manifestPromise = (async () => {
+    const response = await fetch(DIALOGUE_MANIFEST_PATH);
     if (!response.ok) {
+      manifestPromise = null;
       return null;
     }
+    const manifest = parseDialogueManifest(await response.json());
+    manifestCache = manifest;
+    return manifest;
+  })();
 
-  return parseDialogueManifest(await response.json());
+  return manifestPromise;
 }
 
 function getDialogueVoice(