diff --git a/replit.md b/replit.md
index 29896ab5..8158f6cc 100644
--- a/replit.md
+++ b/replit.md
@@ -268,4 +268,25 @@ Preferred communication style: Simple, everyday language.
 - All async operations properly handle errors with user feedback
 
 **Import Fixes:**
-- Fixed sonner.tsx to import `useTheme` from local `@/components/theme/ThemeProvider` instead of incorrect `next-themes` package
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+- Fixed sonner.tsx to import `useTheme` from local `@/components/theme/ThemeProvider` instead of incorrect `next-themes` package
+
+### Additional Bug Fixes and Security Improvements (October 7, 2025)
+
+**Security Enhancements:**
+- `supabase/functions/upload-image/index.ts`: Added authentication requirements for POST and GET operations to prevent unauthorized access to image uploads and status checks
+- All image operations now verify JWT tokens via Supabase auth before proceeding with Cloudflare API calls
+- Added TODO comments for restricting CORS to specific domains in production environments
+
+**Performance Optimizations:**
+- `src/components/upload/PhotoUpload.tsx`: Optimized session token fetching to retrieve once before polling loop instead of on every iteration, reducing unnecessary authentication calls and improving upload performance
+
+**Enhanced Input Validation:**
+- `supabase/functions/create-novu-subscriber/index.ts`: Comprehensive validation added for all fields:
+  - Required fields: subscriberId and email with format validation
+  - Optional fields: firstName/lastName (max 100 chars), phone (international format), avatar (valid URL), data (object type with 10KB size limit)
+  - Graceful handling of malformed JSON with proper 400 error responses instead of 500
+
+**Error Handling Improvements:**
+- `src/lib/versioningHelpers.ts`: Added `instanceof Error` checks before accessing `error.message` to prevent runtime crashes
+- `src/lib/notificationService.ts`: Added safe error message extraction with fallback for non-Error objects
+- All error handlers now provide user-friendly messages while maintaining detailed logging
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