diff --git a/src/interfaces/api/handlers/auth_handler.rs b/src/interfaces/api/handlers/auth_handler.rs
index f4007a66..4d66b474 100755
--- a/src/interfaces/api/handlers/auth_handler.rs
+++ b/src/interfaces/api/handlers/auth_handler.rs
@@ -674,4 +674,4 @@ async fn oidc_exchange(
     );
     cookie_auth::append_csrf_cookie(response.headers_mut(), auth_response.expires_in);
     Ok(response)
-}
\ No newline at end of file
+}
diff --git a/src/interfaces/api/handlers/file_handler.rs b/src/interfaces/api/handlers/file_handler.rs
index 495b0a14..296f7504 100755
--- a/src/interfaces/api/handlers/file_handler.rs
+++ b/src/interfaces/api/handlers/file_handler.rs
@@ -106,7 +106,11 @@ impl FileHandler {
                 if let Some(ref fid) = folder_id {
                     use crate::application::ports::inbound::FolderUseCase;
                     let folder_service = &state.applications.folder_service;
-                    if folder_service.get_folder_owned(fid, &auth_user.id).await.is_err() {
+                    if folder_service
+                        .get_folder_owned(fid, &auth_user.id)
+                        .await
+                        .is_err()
+                    {
                         tracing::warn!(
                             "⛔ UPLOAD REJECTED (IDOR): user='{}' attempted upload to folder '{}' owned by another user",
                             auth_user.username,
@@ -366,10 +370,8 @@ impl FileHandler {
                     .unwrap()
                     .into_response()
             }
-            Err(err) => {
-                AppError::internal_error(format!("Thumbnail generation failed: {}", err))
-                    .into_response()
-            }
+            Err(err) => AppError::internal_error(format!("Thumbnail generation failed: {}", err))
+                .into_response(),
         }
     }
 
@@ -542,9 +544,7 @@ impl FileHandler {
                     .unwrap()
                     .into_response(),
             },
-            Err(err) => {
-                AppError::from(err).into_response()
-            }
+            Err(err) => AppError::from(err).into_response(),
         }
     }
 
@@ -594,9 +594,7 @@ impl FileHandler {
                     .insert(header::ETAG, header::HeaderValue::from_str(&etag).unwrap());
                 resp
             }
-            Err(err) => {
-                AppError::from(err).into_response()
-            }
+            Err(err) => AppError::from(err).into_response(),
         }
     }
 
@@ -635,8 +633,7 @@ impl FileHandler {
                     let file_path = state.core.dedup_service.blob_path(&blob_hash);
                     tokio::spawn(async move {
                         tracing::info!("🖼️ Generating thumbnails for: {}", file_id);
-                        thumbnail_service
-                            .generate_all_sizes_background(file_id, file_path);
+                        thumbnail_service.generate_all_sizes_background(file_id, file_path);
                     });
                 }
                 Err(e) => {
@@ -726,7 +723,7 @@ impl FileHandler {
 
         match result {
             Ok(_) => StatusCode::NO_CONTENT.into_response(),
-            Err(err) => AppError::from(err).into_response()
+            Err(err) => AppError::from(err).into_response(),
         }
     }
 
@@ -758,7 +755,7 @@ impl FileHandler {
         let mgmt = &state.applications.file_management_service;
         match mgmt.rename_file_owned(&id, &auth_user.id, &new_name).await {
             Ok(file_dto) => (StatusCode::OK, Json(file_dto)).into_response(),
-            Err(err) => AppError::from(err).into_response()
+            Err(err) => AppError::from(err).into_response(),
         }
     }
 
@@ -778,7 +775,7 @@ impl FileHandler {
             .await
         {
             Ok(file) => (StatusCode::OK, Json(file)).into_response(),
-            Err(err) => AppError::from(err).into_response()
+            Err(err) => AppError::from(err).into_response(),
         }
     }
 
@@ -797,7 +794,7 @@ impl FileHandler {
         let mgmt = &state.applications.file_management_service;
         match mgmt.move_file_owned(&id, &auth_user.id, folder_id).await {
             Ok(file_dto) => (StatusCode::OK, Json(file_dto)).into_response(),
-            Err(err) => AppError::from(err).into_response()
+            Err(err) => AppError::from(err).into_response(),
         }
     }
 
@@ -856,9 +853,7 @@ impl FileHandler {
             })
             .collect();
 
-        format!(
-            "{disposition}; filename=\"{ascii_safe}\"; filename*=UTF-8''{encoded}"
-        )
+        format!("{disposition}; filename=\"{ascii_safe}\"; filename*=UTF-8''{encoded}")
     }
 
     /// Build a 201 Created JSON response.
diff --git a/static/js/app/authSession.js b/static/js/app/authSession.js
index ae64bf38..8f3f3979 100755
--- a/static/js/app/authSession.js
+++ b/static/js/app/authSession.js
@@ -92,24 +92,36 @@ async function checkAuthentication() {
 
             window.updateStorageUsageDisplay(userData);
 
-            refreshUserData().then(freshData => {
-                if (freshData) {
-                    console.log('Storage usage updated from server');
-                } else {
-                    // Session expired — try silent refresh first
-                    console.warn('Session may have expired, trying refresh...');
-                    fetch('/api/auth/refresh', { method: 'POST', credentials: 'same-origin', headers: { 'Content-Type': 'application/json', ...getCsrfHeaders() }, body: '{}' })
-                        .then(r => r.ok ? refreshUserData() : Promise.reject(new Error('refresh failed')))
-                        .catch(() => {
-                            localStorage.removeItem(USER_DATA_KEY);
-                            window.location.href = '/login?source=session_expired';
-                        });
+            // Validate session BEFORE loading files to avoid 401 race condition
+            const freshData = await refreshUserData();
+            if (freshData) {
+                console.log('Storage usage updated from server');
+            } else {
+                // Session expired — try silent refresh first
+                console.warn('Session may have expired, trying refresh...');
+                try {
+                    const r = await fetch('/api/auth/refresh', {
+                        method: 'POST',
+                        credentials: 'same-origin',
+                        headers: { 'Content-Type': 'application/json', ...getCsrfHeaders() },
+                        body: '{}'
+                    });
+                    if (r.ok) {
+                        await refreshUserData();
+                    } else {
+                        localStorage.removeItem(USER_DATA_KEY);
+                        window.location.href = '/login?source=session_expired';
+                        return;
+                    }
+                } catch (err) {
+                    localStorage.removeItem(USER_DATA_KEY);
+                    window.location.href = '/login?source=session_expired';
+                    return;
                 }
-            }).catch(err => {
-                console.warn('Could not refresh user data:', err);
-            });
+            }
 
-            resolveHomeFolder().then(() => window.loadFiles());
+            await resolveHomeFolder();
+            window.loadFiles();
         } else {
             // No cached user data — must verify session from server
             console.log('No cached user data, fetching from server');