diff --git a/frontend/templates/index.html b/frontend/templates/index.html
index e6ba601..131b0b5 100644
--- a/frontend/templates/index.html
+++ b/frontend/templates/index.html
@@ -137,6 +137,7 @@ async function startSession(e) {
   btn.disabled = false;
 }
 async function handleUpload(formData) {
+  console.log('handleUpload called, file:', formData.get('source_file')?.name);
   return new Promise((resolve) => {
     const xhr = new XMLHttpRequest();
     const file = formData.get('source_file');