feat: Show user-friendly error messages for failed CV checks

- Store specific error message in ProcessingStage field on failure
- Display meaningful messages like "No useful data could be extracted"
- Handle common failure scenarios: scanned images, API limits, encrypted files

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/RealCV.Infrastructure/Jobs/ProcessCVCheckJob.cs

@@ -292,6 +292,8 @@ public sealed class ProcessCVCheckJob
             try
             {
                 cvCheck.Status = CheckStatus.Failed;
+                // Store a user-friendly error message
+                cvCheck.ProcessingStage = GetUserFriendlyErrorMessage(ex);
                 // Use CancellationToken.None to ensure failure status is saved even if original token is cancelled
                 await _dbContext.SaveChangesAsync(CancellationToken.None);
             }
@@ -1424,4 +1426,39 @@ public sealed class ProcessCVCheckJob
                 obj.FlagType?.ToUpperInvariant() ?? "");
         }
     }
+
+    /// <summary>
+    /// Returns a user-friendly error message based on the exception type.
+    /// </summary>
+    private static string GetUserFriendlyErrorMessage(Exception ex)
+    {
+        // Check for specific error patterns
+        var message = ex.Message;
+
+        if (message.Contains("no extractable data", StringComparison.OrdinalIgnoreCase) ||
+            message.Contains("Could not extract any employment", StringComparison.OrdinalIgnoreCase))
+        {
+            return "No useful data could be extracted from this CV. The file may be a scanned image or in an unsupported format.";
+        }
+
+        if (message.Contains("API usage limits", StringComparison.OrdinalIgnoreCase) ||
+            message.Contains("rate limit", StringComparison.OrdinalIgnoreCase))
+        {
+            return "Service temporarily unavailable. Please try again in a few minutes.";
+        }
+
+        if (message.Contains("Could not extract text", StringComparison.OrdinalIgnoreCase))
+        {
+            return "Could not read the CV file. Please ensure it's a valid PDF or DOCX document.";
+        }
+
+        if (message.Contains("password", StringComparison.OrdinalIgnoreCase) ||
+            message.Contains("encrypted", StringComparison.OrdinalIgnoreCase))
+        {
+            return "This CV appears to be password-protected. Please upload an unprotected version.";
+        }
+
+        // Default message
+        return "An error occurred while processing your CV. Please try uploading again.";
+    }
 }

src/RealCV.Web/Components/Pages/Report.razor

@@ -74,7 +74,7 @@
                             <path d="M7.002 12a1 1 0 1 1 2 0 1 1 0 0 1-2 0zM7.1 5.995a.905.905 0 1 1 1.8 0l-.35 3.507a.552.552 0 0 1-1.1 0L7.1 5.995z"/>
                         </svg>
                         <h4 class="mb-2">Processing Failed</h4>
-                        <p class="text-muted">We encountered an error processing your CV. Please try uploading again.</p>
+                        <p class="text-muted">@(!string.IsNullOrEmpty(_check.ProcessingStage) ? _check.ProcessingStage : "We encountered an error processing your CV. Please try uploading again.")</p>
                     }
 
                     <p class="text-muted small mt-4">