Adding a copy fallback if xsel is missing. (#2550)

* Adding workaround for new copy api.

* remove content when copy is successful

---------

Co-authored-by: Aasim Khan <aasimkhan@gmail.com>

Author: aasimkhan30

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/Contracts/CopyResults2Request.cs

@@ -64,6 +64,11 @@ public class CopyResults2RequestParams : SubsetParams
     /// </summary>
     public class CopyResults2RequestResult
     {
+        /// <summary>
+        /// The content to be copied to the clipboard.
+        /// If this is populated, the client is responsible for copying it to the clipboard.
+        /// </summary>
+        public string Content { get; set; }
     }
 
     /// <summary>

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/QueryExecutionService.cs

@@ -1004,8 +1004,16 @@ internal async Task HandleCopyResults2Request(CopyResults2RequestParams requestP
 
                 cts.Token.ThrowIfCancellationRequested();
 
-                await ClipboardService.SetTextAsync(content);
-                await requestContext.SendResult(new CopyResults2RequestResult());
+                try
+                {
+                    await ClipboardService.SetTextAsync(content);
+                    await requestContext.SendResult(new CopyResults2RequestResult());
+                }
+                catch (Exception)
+                {
+                    // If clipboard copy fails (e.g. missing xsel on Linux), send content back to client
+                    await requestContext.SendResult(new CopyResults2RequestResult { Content = content });
+                }
             }
             catch (OperationCanceledException)
             {