diff --git a/.jules/sentinel.md b/.jules/sentinel.md
new file mode 100644
index 00000000..5bd16bb0
--- /dev/null
+++ b/.jules/sentinel.md
@@ -0,0 +1,4 @@
+## 2024-05-17 - Error Response Sanitization
+**Vulnerability:** Detailed Cloudinary and API service errors were being exposed in the HTTP 500 response bodies in `/api/upload/route.ts`.
+**Learning:** Returning `error: error.message` in Catch blocks directly surfaces internal server configurations, credentials status, and backend stack implementation details.
+**Prevention:** Always log the detailed error internally (`console.error`) and return a generic `NextResponse.json({ error: "Failed to perform action" })` to the client API response.
diff --git a/src/app/api/upload/route.ts b/src/app/api/upload/route.ts
index 1664e115..70897221 100644
--- a/src/app/api/upload/route.ts
+++ b/src/app/api/upload/route.ts
@@ -12,7 +12,7 @@ export async function POST(request: NextRequest) {
         api_secret: !!process.env.CLOUDINARY_API_SECRET
       });
       return NextResponse.json(
-        { error: 'Cloudinary is not configured. Please set environment variables.' },
+        { error: 'Internal server error during upload' },
         { status: 500 }
       );
     }
@@ -60,7 +60,7 @@ export async function POST(request: NextRequest) {
   } catch (error: any) {
     console.error('Upload error:', error);
 
-    // Return detailed error message
+    // Construct detailed error message for server logs ONLY
     const errorMessage = error?.message || error?.error?.message || 'Failed to upload image';
     const errorDetails = {
       error: errorMessage,
@@ -70,8 +70,9 @@ export async function POST(request: NextRequest) {
 
     console.error('Full error details:', errorDetails);
 
+    // Return sanitized generic error message to client
     return NextResponse.json(
-      errorDetails,
+      { error: 'Failed to upload image' },
       { status: 500 }
     );
   }