Fix swallowed Tab after raw ANSI Shift+Tab in ted

src/Terminal.Gui.Editor/AnsiInputProcessorState.cs

@@ -0,0 +1,34 @@
+using System.Reflection;
+using Terminal.Gui.App;
+using Terminal.Gui.Drivers;
+
+namespace Terminal.Gui.Editor;
+
+internal static class AnsiInputProcessorState
+{
+    private const string PendingPrintableSuppressionFieldName = "_pendingPrintableSuppression";
+
+    public static void ClearPendingPrintableSuppression (IApplication? app)
+    {
+        if (app?.Driver?.GetInputProcessor () is not AnsiInputProcessor processor)
+        {
+            return;
+        }
+
+        // Terminal.Gui 2.1.1-develop.98 suppresses the next printable fallback key after parsing
+        // ANSI Shift+Tab (ESC [ Z) because Shift+Tab reports Tab as printable text. Until TG exposes
+        // public input-processor state for this, clear that one-shot suppression after the editor
+        // handles Unindent so the user's next Tab reaches us. If TG renames this private field, the
+        // type checks below intentionally no-op; the only consequence is the original Tab suppression.
+        FieldInfo? field = typeof (AnsiInputProcessor).GetField (
+            PendingPrintableSuppressionFieldName,
+            BindingFlags.Instance | BindingFlags.NonPublic);
+
+        if (field?.FieldType != typeof (string))
+        {
+            return;
+        }
+
+        field.SetValue (processor, string.Empty);
+    }
+}

src/Terminal.Gui.Editor/Editor.Indentation.cs

@@ -52,12 +52,21 @@ private bool Unindent ()
 
         if (ReadOnly)
         {
+            AnsiInputProcessorState.ClearPendingPrintableSuppression (App);
+
             return true;
         }
 
         if (HasMultipleCarets)
         {
-            return MultiCaretUnindent ();
+            var handled = MultiCaretUnindent ();
+
+            if (handled)
+            {
+                AnsiInputProcessorState.ClearPendingPrintableSuppression (App);
+            }
+
+            return handled;
         }
 
         List<DocumentLine> lines = HasSelection && SelectionSpansMultipleLines ()
@@ -78,6 +87,8 @@ private bool Unindent ()
 
         if (removals.Count == 0)
         {
+            AnsiInputProcessorState.ClearPendingPrintableSuppression (App);
+
             return true;
         }
 
@@ -102,6 +113,8 @@ private bool Unindent ()
                 AdjustOffsetAfterRemovals (selectionEnd, removals));
         }
 
+        AnsiInputProcessorState.ClearPendingPrintableSuppression (App);
+
         return true;
     }
 

tests/Terminal.Gui.Editor.IntegrationTests/EditorTabTests.cs

@@ -1,8 +1,10 @@
 // Codex - GPT-5
 
 using Terminal.Gui.Editor.IntegrationTests.Testing;
+using Terminal.Gui.Drivers;
 using Terminal.Gui.Input;
 using Terminal.Gui.Testing;
+using Ted;
 using Xunit;
 
 namespace Terminal.Gui.Editor.IntegrationTests;
@@ -144,4 +146,43 @@ public async Task Backspace_At_End_Of_Leading_Whitespace_Removes_One_Indentation
         Assert.Equal ("alpha", fx.Top.Editor.Document!.Text);
         Assert.Equal (0, fx.Top.Editor.CaretOffset);
     }
+
+    [Fact]
+    public async Task Ted_RawAnsi_Tab_After_ShiftTab_Reindents_Line_On_First_Keypress ()
+    {
+        await using AppFixture<TedApp> fx = new (() => new TedApp ());
+        fx.Top.Editor.SetFocus ();
+        fx.Top.Editor.Document!.Text = "hello world";
+        fx.Top.Editor.CaretOffset = 0;
+
+        InjectAnsi (fx, "\t");
+
+        Assert.Equal ("    hello world", fx.Top.Editor.Document.Text);
+        Assert.Equal (4, fx.Top.Editor.CaretOffset);
+
+        InjectAnsi (fx, "\u001b[Z");
+
+        Assert.Equal ("hello world", fx.Top.Editor.Document.Text);
+        Assert.Equal (0, fx.Top.Editor.CaretOffset);
+
+        InjectAnsi (fx, "\t");
+
+        Assert.Equal ("    hello world", fx.Top.Editor.Document.Text);
+        Assert.Equal (4, fx.Top.Editor.CaretOffset);
+    }
+
+    private static void InjectAnsi (AppFixture<TedApp> fx, string sequence)
+    {
+        if (fx.App.Driver!.GetInputProcessor () is not AnsiInputProcessor processor)
+        {
+            throw new InvalidOperationException ("ANSI input processor is required for raw ANSI input tests.");
+        }
+
+        foreach (var ch in sequence)
+        {
+            processor.InputQueue.Enqueue (ch);
+        }
+
+        processor.ProcessQueue ();
+    }
 }