diff --git a/api/lab/descargar_orden.php b/api/lab/descargar_orden.php
index d166b51..5270c6a 100644
--- a/api/lab/descargar_orden.php
+++ b/api/lab/descargar_orden.php
@@ -46,12 +46,38 @@ if (!$path || !$base || strpos($path, $base) !== 0 || !is_file($path)) {
     exit;
 }
 
-// Detectar MIME real
-$finfo = finfo_open(FILEINFO_MIME_TYPE);
-$mime  = finfo_file($finfo, $path);
-finfo_close($finfo);
+// Detectar MIME real — 3 capas para máxima fiabilidad con archivos .bin
 
-// Mapa de extensiones como fallback
+// Capa 1: finfo (usa magic bytes internamente)
+$mime = '';
+if (function_exists('finfo_open')) {
+    $fi   = finfo_open(FILEINFO_MIME_TYPE);
+    $mime = $fi ? (string)finfo_file($fi, $path) : '';
+    if ($fi) finfo_close($fi);
+}
+
+// Capa 2: Lectura manual de magic bytes (funciona aunque finfo falle o devuelva octet-stream)
+if (!$mime || $mime === 'application/octet-stream') {
+    $handle = fopen($path, 'rb');
+    $bytes  = $handle ? fread($handle, 12) : '';
+    if ($handle) fclose($handle);
+
+    if (substr($bytes, 0, 3) === "\xFF\xD8\xFF") {
+        $mime = 'image/jpeg';
+    } elseif (substr($bytes, 0, 8) === "\x89PNG\r\n\x1a\n") {
+        $mime = 'image/png';
+    } elseif (substr($bytes, 0, 5) === '%PDF-') {
+        $mime = 'application/pdf';
+    } elseif (substr($bytes, 0, 6) === 'GIF89a' || substr($bytes, 0, 6) === 'GIF87a') {
+        $mime = 'image/gif';
+    } elseif (substr($bytes, 0, 4) === 'RIFF' && substr($bytes, 8, 4) === 'WEBP') {
+        $mime = 'image/webp';
+    } elseif (substr($bytes, 0, 2) === 'PK') {
+        $mime = 'application/vnd.openxmlformats-officedocument.wordprocessingml.document';
+    }
+}
+
+// Capa 3: Fallback por extensión declarada
 $ext = strtolower(pathinfo($fileParam, PATHINFO_EXTENSION));
 $mimeMap = [
     'pdf'  => 'application/pdf',