diff --git a/vite.config.ts b/vite.config.ts
index 3b81b0a..020a984 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -13,7 +13,9 @@ const __dirname = fileURLToPath(new URL(".", import.meta.url));
 const MAX_MAP_PAYLOAD_BYTES = 1024 * 1024;
 const MAX_SRT_PAYLOAD_BYTES = 256 * 1024;
 const JSON_HEADERS = { "Content-Type": "application/json" };
-type JsonResponseBody = Readonly<Record<string, string | boolean>>;
+type JsonValue = string | number | boolean | null | JsonValue[] | JsonObject;
+type JsonObject = { readonly [key: string]: JsonValue };
+type JsonResponseBody = Readonly<Record<string, JsonValue>>;
 const SRT_VOICES = new Set(["narrateur", "fermier", "electricienne"]);
 const SRT_LANGUAGES = new Set(["fr", "en"]);
 
@@ -138,12 +140,49 @@ const saveSrtPlugin = (): Plugin => ({
   },
 });
 
+const validateDialoguesPlugin = (): Plugin => ({
+  name: "validate-dialogues-api",
+  configureServer(server) {
+    server.middlewares.use("/api/validate-dialogues", async (req, res) => {
+      if (req.method !== "GET") {
+        sendJson(res, 405, { error: "Method not allowed" }, { Allow: "GET" });
+        return;
+      }
+
+      try {
+        const result = await validateDialogueAssets();
+        sendJson(res, result.valid ? 200 : 400, result);
+      } catch (err) {
+        const message = err instanceof Error ? err.message : "Unknown error";
+        sendJson(res, 500, { error: message });
+      }
+    });
+  },
+});
+
 interface SrtPayload {
   voice: string;
   language: string;
   content: string;
 }
 
+interface DialogueManifestData {
+  voices: DialogueVoiceData[];
+  dialogues: DialogueData[];
+}
+
+interface DialogueVoiceData {
+  id: string;
+  subtitles: Partial<Record<"fr" | "en", string>>;
+}
+
+interface DialogueData {
+  id: string;
+  voice: string;
+  audio: string;
+  subtitleCueIndex: number;
+}
+
 function isSrtPayload(data: unknown): data is SrtPayload {
   if (!data || typeof data !== "object") return false;
 
@@ -177,8 +216,175 @@ function isValidSrtContent(content: string): boolean {
   return true;
 }
 
+interface DialogueValidationResult extends JsonObject {
+  valid: boolean;
+  errors: string[];
+  warnings: string[];
+}
+
+async function validateDialogueAssets(): Promise<DialogueValidationResult> {
+  const errors: string[] = [];
+  const warnings: string[] = [];
+  const manifestPath = path.resolve(
+    __dirname,
+    "public/sounds/dialogue/dialogues.json",
+  );
+  const manifestContent = await fs.promises.readFile(manifestPath, "utf8");
+  const manifest = parseDialogueManifestData(JSON.parse(manifestContent));
+
+  const subtitleCueCache = new Map<string, Set<number>>();
+
+  for (const voice of manifest.voices) {
+    const frSubtitlePath = voice.subtitles.fr;
+    if (!frSubtitlePath) {
+      errors.push(`Voice ${voice.id} must define a French subtitle file`);
+    } else {
+      await validateSubtitleFile(frSubtitlePath, errors, subtitleCueCache);
+    }
+
+    const enSubtitlePath = voice.subtitles.en;
+    if (enSubtitlePath) {
+      const resolvedEnPath = resolvePublicPath(enSubtitlePath);
+      if (!resolvedEnPath || !fs.existsSync(resolvedEnPath)) {
+        warnings.push(`English subtitle file missing for voice ${voice.id}`);
+      }
+    }
+  }
+
+  for (const dialogue of manifest.dialogues) {
+    const audioPath = resolvePublicPath(dialogue.audio);
+    if (!audioPath || !fs.existsSync(audioPath)) {
+      errors.push(`Dialogue ${dialogue.id} audio file is missing`);
+    }
+
+    const voice = manifest.voices.find(
+      (item: DialogueVoiceData) => item.id === dialogue.voice,
+    );
+    const frSubtitlePath = voice?.subtitles.fr;
+    const cueIndexes = frSubtitlePath
+      ? subtitleCueCache.get(frSubtitlePath)
+      : undefined;
+
+    if (!cueIndexes?.has(dialogue.subtitleCueIndex)) {
+      errors.push(
+        `Dialogue ${dialogue.id} references missing cue ${dialogue.subtitleCueIndex}`,
+      );
+    }
+  }
+
+  return {
+    valid: errors.length === 0,
+    errors,
+    warnings,
+  };
+}
+
+function parseDialogueManifestData(data: unknown): DialogueManifestData {
+  if (!isRecord(data) || data.version !== 1) {
+    throw new Error("Invalid dialogue manifest");
+  }
+
+  if (!Array.isArray(data.voices) || !Array.isArray(data.dialogues)) {
+    throw new Error("Dialogue manifest requires voices and dialogues arrays");
+  }
+
+  const voices = data.voices.map(parseDialogueVoiceData);
+  const voiceIds = new Set(voices.map((voice) => voice.id));
+  const dialogues = data.dialogues.map((dialogue) =>
+    parseDialogueData(dialogue, voiceIds),
+  );
+
+  return { voices, dialogues };
+}
+
+function parseDialogueVoiceData(data: unknown): DialogueVoiceData {
+  if (!isRecord(data) || typeof data.id !== "string") {
+    throw new Error("Invalid dialogue voice");
+  }
+
+  if (!isRecord(data.subtitles)) {
+    throw new Error(`Dialogue voice ${data.id} must define subtitles`);
+  }
+
+  const subtitles: DialogueVoiceData["subtitles"] = {};
+  if (typeof data.subtitles.fr === "string") subtitles.fr = data.subtitles.fr;
+  if (typeof data.subtitles.en === "string") subtitles.en = data.subtitles.en;
+
+  return {
+    id: data.id,
+    subtitles,
+  };
+}
+
+function parseDialogueData(data: unknown, voiceIds: Set<string>): DialogueData {
+  if (!isRecord(data)) {
+    throw new Error("Invalid dialogue definition");
+  }
+
+  if (
+    typeof data.id !== "string" ||
+    typeof data.voice !== "string" ||
+    !voiceIds.has(data.voice) ||
+    typeof data.audio !== "string" ||
+    typeof data.subtitleCueIndex !== "number" ||
+    !Number.isInteger(data.subtitleCueIndex)
+  ) {
+    throw new Error("Invalid dialogue definition");
+  }
+
+  return {
+    id: data.id,
+    voice: data.voice,
+    audio: data.audio,
+    subtitleCueIndex: data.subtitleCueIndex,
+  };
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null;
+}
+
+async function validateSubtitleFile(
+  publicPath: string,
+  errors: string[],
+  subtitleCueCache: Map<string, Set<number>>,
+): Promise<void> {
+  const subtitlePath = resolvePublicPath(publicPath);
+  if (!subtitlePath || !fs.existsSync(subtitlePath)) {
+    errors.push(`Subtitle file ${publicPath} is missing`);
+    return;
+  }
+
+  const content = await fs.promises.readFile(subtitlePath, "utf8");
+  if (!isValidSrtContent(content)) {
+    errors.push(`Subtitle file ${publicPath} is invalid`);
+    return;
+  }
+
+  subtitleCueCache.set(
+    publicPath,
+    new Set(parseSrt(content).map((cue) => cue.index)),
+  );
+}
+
+function resolvePublicPath(publicPath: string): string | null {
+  if (!publicPath.startsWith("/")) return null;
+
+  const publicRoot = path.resolve(__dirname, "public");
+  const resolvedPath = path.resolve(publicRoot, publicPath.slice(1));
+
+  if (!resolvedPath.startsWith(`${publicRoot}${path.sep}`)) return null;
+
+  return resolvedPath;
+}
+
 export default defineConfig({
-  plugins: [react(), saveMapPlugin(), saveSrtPlugin()],
+  plugins: [
+    react(),
+    saveMapPlugin(),
+    saveSrtPlugin(),
+    validateDialoguesPlugin(),
+  ],
   resolve: {
     alias: {
       "@": fileURLToPath(new URL("./src", import.meta.url)),