Add --delete-source option and interactive prompt to project convert

src/Cli/Microsoft.DotNet.Cli.Definitions/CommandDefinitionStrings.resx

@@ -939,6 +939,9 @@ If not specified the file will be generated inside the default 'TestResults' dir
   <data name="ProjectConvertDryRun" xml:space="preserve">
     <value>Determines changes without actually modifying the file system</value>
   </data>
+  <data name="ProjectConvertDeleteSource" xml:space="preserve">
+    <value>Delete the source file after conversion</value>
+  </data>
   <data name="ProjectManifest" xml:space="preserve">
     <value>PROJECT_MANIFEST</value>
   </data>

src/Cli/Microsoft.DotNet.Cli.Definitions/Commands/Project/ProjectConvertCommandDefinition.cs

@@ -34,6 +34,12 @@ internal sealed class ProjectConvertCommandDefinition : Command
         Arity = ArgumentArity.Zero,
     };
 
+    public readonly Option<bool> DeleteSourceOption = new("--delete-source")
+    {
+        Description = CommandDefinitionStrings.ProjectConvertDeleteSource,
+        Arity = ArgumentArity.Zero,
+    };
+
     public ProjectConvertCommandDefinition()
         : base("convert", CommandDefinitionStrings.ProjectConvertAppFullName)
     {
@@ -42,5 +48,6 @@ public ProjectConvertCommandDefinition()
         Options.Add(ForceOption);
         Options.Add(InteractiveOption);
         Options.Add(DryRunOption);
+        Options.Add(DeleteSourceOption);
     }
 }

src/Cli/dotnet/Commands/CliCommandStrings.resx

@@ -849,6 +849,24 @@ Tool '{1}' (version '{2}') was successfully installed. Entry is added to the man
     <value>Dry run: would create file: {0}</value>
     <comment>{0} is the file full path.</comment>
   </data>
+  <data name="ProjectConvertAskDeleteSource" xml:space="preserve">
+    <value>Delete the source file '{0}' after conversion?</value>
+    <comment>{0} is the source file path.</comment>
+  </data>
+  <data name="ProjectConvertDeletedSourceFile" xml:space="preserve">
+    <value>Deleted source file: {0}</value>
+    <comment>{0} is the source file path.</comment>
+  </data>
+  <data name="ProjectConvertWouldDeleteSourceFile" xml:space="preserve">
+    <value>Dry run: would delete source file: {0}</value>
+    <comment>{0} is the source file path.</comment>
+  </data>
+  <data name="ProjectConvertDeleteSourceChoiceYes" xml:space="preserve">
+    <value>Yes - delete the source file</value>
+  </data>
+  <data name="ProjectConvertDeleteSourceChoiceNo" xml:space="preserve">
+    <value>No - keep the source file</value>
+  </data>
   <data name="ProjectsHeader" xml:space="preserve">
     <value>Project(s)</value>
   </data>

src/Cli/dotnet/Commands/Project/Convert/ProjectConvertCommand.cs

@@ -10,6 +10,7 @@
 using Microsoft.DotNet.Cli.Utils;
 using Microsoft.DotNet.FileBasedPrograms;
 using Microsoft.DotNet.ProjectTools;
+using Spectre.Console;
 
 namespace Microsoft.DotNet.Cli.Commands.Project.Convert;
 
@@ -19,6 +20,7 @@ internal sealed class ProjectConvertCommand : CommandBase<ProjectConvertCommandD
     private readonly string? _outputDirectory;
     private readonly bool _force;
     private readonly bool _dryRun;
+    private readonly bool _deleteSource;
 
     public ProjectConvertCommand(ParseResult parseResult)
         : base(parseResult)
@@ -27,6 +29,7 @@ public ProjectConvertCommand(ParseResult parseResult)
         _outputDirectory = parseResult.GetValue(Definition.OutputOption)?.FullName;
         _force = parseResult.GetValue(Definition.ForceOption);
         _dryRun = parseResult.GetValue(Definition.DryRunOption);
+        _deleteSource = parseResult.GetValue(Definition.DeleteSourceOption);
     }
 
     public override int Execute()
@@ -102,6 +105,13 @@ public override int Execute()
             CopyFile(item.FullPath, targetItemFullPath);
         }
 
+        // Handle deletion of source file if requested.
+        bool shouldDeleteSource = _deleteSource || TryAskForDeleteSource(file);
+        if (shouldDeleteSource)
+        {
+            DeleteSourceFile(file);
+        }
+
         return 0;
 
         void CreateDirectory(string path)
@@ -282,4 +292,43 @@ private string DetermineOutputDirectory(string file)
             ? result
             : null;
     }
+
+    private bool TryAskForDeleteSource(string sourceFile)
+    {
+        // Don't ask in non-interactive mode or if --delete-source was already specified
+        if (!_parseResult.GetValue<bool>(CommonOptions.InteractiveOptionName))
+        {
+            return false;
+        }
+
+        try
+        {
+            // Use Spectre.Console for a better interactive experience
+            var choice = Spectre.Console.AnsiConsole.Prompt(
+                new SelectionPrompt<string>()
+                    .Title($"[cyan]{Markup.Escape(string.Format(CliCommandStrings.ProjectConvertAskDeleteSource, Path.GetFileName(sourceFile)))}[/]")
+                    .AddChoices([CliCommandStrings.ProjectConvertDeleteSourceChoiceYes, CliCommandStrings.ProjectConvertDeleteSourceChoiceNo])
+            );
+
+            return choice == CliCommandStrings.ProjectConvertDeleteSourceChoiceYes;
+        }
+        catch (Exception)
+        {
+            // If Spectre.Console fails (e.g., terminal doesn't support it), fall back to basic prompt
+            return false;
+        }
+    }
+
+    private void DeleteSourceFile(string sourceFile)
+    {
+        if (_dryRun)
+        {
+            Reporter.Output.WriteLine(CliCommandStrings.ProjectConvertWouldDeleteSourceFile, sourceFile);
+        }
+        else
+        {
+            File.Delete(sourceFile);
+            Reporter.Output.WriteLine(CliCommandStrings.ProjectConvertDeletedSourceFile, sourceFile);
+        }
+    }
 }