fix core dump on export option

hanatui/src/Tui/OperationForms.cs

@@ -14,6 +14,21 @@ public static class OperationForms
     // Shared helpers
     // -------------------------------------------------------------------------
 
+    /// <summary>
+    /// A choice item that keeps the real value separate from the display label.
+    /// The display label is pre-escaped plain text — never interpreted as markup.
+    /// </summary>
+    private sealed class SchemaChoice
+    {
+        public string Display { get; init; } = "";
+        public string? Value  { get; init; }   // null = cancel, "" = manual entry
+
+        public static readonly SchemaChoice Manual = new() { Display = "[ Enter manually ]", Value = "" };
+        public static readonly SchemaChoice Cancel = new() { Display = "[ Cancel ]",         Value = null };
+
+        public override string ToString() => Display;
+    }
+
     /// <summary>
     /// Fetches the schema list with a spinner, then shows an arrow-key picker.
     /// Returns the selected schema, or null if cancelled.
@@ -38,36 +53,35 @@ public static class OperationForms
         if (error is not null)
             AnsiConsole.MarkupLine($"[yellow][[WARN]] Could not fetch schemas: {Markup.Escape(error)}[/]");
 
-        // Use sentinel strings as values so no markup leaks into choice labels
-        const string manualSentinel = "__MANUAL__";
-        const string cancelSentinel = "__CANCEL__";
+        // Build typed choices. Display is plain text; ToString() is what SelectionPrompt shows.
+        var choices = schemas
+            .Select(s => new SchemaChoice { Display = s, Value = s })
+            .ToList();
+        choices.Add(SchemaChoice.Manual);
+        choices.Add(SchemaChoice.Cancel);
 
-        var choiceValues = new List<string>(schemas) { manualSentinel, cancelSentinel };
-
-        var prompt = new SelectionPrompt<string>()
+        // UseConverter returns Display which is already plain text.
+        // We also set the prompt to NOT interpret converter output as markup by
+        // escaping it — belt-and-suspenders.
+        var prompt = new SelectionPrompt<SchemaChoice>()
             .Title($"[bold]{Markup.Escape(title)}[/]")
             .PageSize(15)
             .HighlightStyle(Style.Parse("bold dodgerblue1"))
-            .UseConverter(v => v switch
-            {
-                manualSentinel => "[ Enter manually ]",
-                cancelSentinel => "[ Cancel ]",
-                _ => Markup.Escape(v),
-            })
-            .AddChoices(choiceValues);
+            .UseConverter(c => Markup.Escape(c.Display))
+            .AddChoices(choices);
 
         var selected = AnsiConsole.Prompt(prompt);
 
-        if (selected == cancelSentinel)
-            return null;
+        if (selected.Value is null)
+            return null;   // Cancel
 
-        if (selected == manualSentinel)
+        if (selected.Value == "")
         {
             var manual = AnsiConsole.Ask<string>("Enter schema name:").Trim();
             return string.IsNullOrWhiteSpace(manual) ? null : manual;
         }
 
-        return selected.Trim();
+        return selected.Value;
     }
 
     private static int PickThreads(string label = "Number of threads")