diff --git a/extensions/index.ts b/extensions/index.ts
index f0436b0..7d77b59 100644
--- a/extensions/index.ts
+++ b/extensions/index.ts
@@ -560,7 +560,24 @@ async function transcribeWithEnne2(file: string): Promise<TranscriptResult> {
 	}
 
 	try {
-		const b64 = fs.readFileSync(file).toString("base64");
+		// Comprimi in MP3 per evitare HTTP 413 su audio lunghi (come il backend gemini)
+		let audioFile = file;
+		let audioFormat = "wav";
+		if (file.toLowerCase().endsWith(".wav")) {
+			const mp3 = file.replace(/\.wav$/i, ".mp3");
+			try {
+				await execFileAsync(
+					"ffmpeg",
+					["-y", "-i", file, "-ac", "1", "-ar", "16000", "-c:a", "libmp3lame", "-q:a", "5", mp3],
+					{ timeout: 60_000 },
+				);
+				audioFile = mp3;
+				audioFormat = "mp3";
+			} catch {
+				/* fallback al WAV */
+			}
+		}
+		const b64 = fs.readFileSync(audioFile).toString("base64");
 		const body = {
 			model,
 			messages: [
@@ -568,7 +585,7 @@ async function transcribeWithEnne2(file: string): Promise<TranscriptResult> {
 					role: "user",
 					content: [
 						{ type: "text", text: "Trascrivi fedelmente il parlato in questo audio. Rispondi solo con la trascrizione." },
-						{ type: "input_audio", input_audio: { data: b64, format: "wav" } },
+						{ type: "input_audio", input_audio: { data: b64, format: audioFormat } },
 					],
 				},
 			],