diff --git a/backend/src/controllers/documentController.ts b/backend/src/controllers/documentController.ts
index 39bc3ea..fdad451 100644
--- a/backend/src/controllers/documentController.ts
+++ b/backend/src/controllers/documentController.ts
@@ -158,6 +158,7 @@ export const documentController = {
       logger.info('✅ Response sent, starting background processing...');
 
       // Process in the background with timeout
+      const self = this; // Capture the controller context
       (async () => {
         const processingTimeout = setTimeout(() => {
           logger.error('Background processing timed out after 30 minutes', { documentId });
@@ -242,7 +243,7 @@ export const documentController = {
             }
             
             // Validate that analysis data contains meaningful content
-            if (!this.isValidAnalysisData(result.analysisData)) {
+            if (!self.isValidAnalysisData(result.analysisData)) {
               throw new Error('Processing completed but analysis data is invalid or contains no meaningful content');
             }
             
@@ -755,7 +756,7 @@ export const documentController = {
   /**
    * Validate that analysis data contains meaningful content
    */
-  private isValidAnalysisData(analysisData: any): boolean {
+  isValidAnalysisData(analysisData: any): boolean {
     if (!analysisData || typeof analysisData !== 'object') {
       return false;
     }
@@ -795,7 +796,7 @@ export const documentController = {
   /**
    * Check if data is sample/fallback data
    */
-  private isSampleData(data: any): boolean {
+  isSampleData(data: any): boolean {
     if (!data || typeof data !== 'object') {
       return false;
     }