🏗️ Refract: C# 13 Escape Sequence & Target-typed new() Syntactic Upgrade

.jules/refract.md

@@ -51,3 +51,7 @@
 ## 2025-02-19 - C# 13 System.Threading.Lock Modernization
 **Observation:** The codebase contained legacy lock statements utilizing an arbitrary object (`object _gate`) for synchronization in `HttpImageResolver.cs`, an obsolete pattern that lacks explicit thread safety semantics compared to modern alternatives.
 **Strategic Action:** Transitioned the synchronization mechanism to use the C# 13 `System.Threading.Lock` type (`System.Threading.Lock _gate = new();`) to enforce deterministic thread safety and structural clarity.
+
+## 2025-05-18 - [Escape Sequence Modernization]
+**Observation:** Ambiguous `\u001B` and `\x1b` escape sequences used for ANSI escape codes.
+**Strategic Action:** Replaced with the C# 13 `\e` escape sequence for precise character representation.

src/Tedd.TUI.Platform.Console/ConsoleInputManager.cs

@@ -33,7 +33,7 @@ public ConsoleInputManager(TuiWindow window)
         // CSI ? 1000 h  (Normal tracking)
         // CSI ? 1003 h  (All motion tracking)
         // CSI ? 1006 h  (SGR ext mode)
-        System.Console.Write("\x1b[?1000h\x1b[?1006h");
+        System.Console.Write("\e[?1000h\e[?1006h");
     }
 
     public IntPtr InputHandle { get; private set; }

src/Tedd.TUI.Platform.Console/TuiApp.cs

@@ -181,7 +181,7 @@ public void Stop()
         try { _inputManager?.Stop(); } catch { }
         try { _platform.Shutdown(); } catch { }
 
-        System.Console.Write("\x1b[?1000l\x1b[?1006l");
+        System.Console.Write("\e[?1000l\e[?1006l");
         System.Console.CursorVisible = true;
         System.Console.ResetColor();
         System.Console.Clear();

src/Tedd.TUI.Platform.LinuxTerminal/ITerm2InlineEncoder.cs

@@ -19,7 +19,7 @@ public string Encode(GraphicPlacement placement)
             return string.Empty;
 
         var sb = new StringBuilder(placement.ImageData.Length * 4 / 3 + 128);
-        sb.Append("\x1b]1337;File=inline=1");
+        sb.Append("\e]1337;File=inline=1");
 
         if (placement.CharWidth > 0)
         {

src/Tedd.TUI.Platform.LinuxTerminal/KittyGraphicsEncoder.cs

@@ -33,7 +33,7 @@ public string Encode(GraphicPlacement placement)
             bool first = offset == 0;
             bool last = offset + len >= base64.Length;
 
-            sb.Append("\x1b_G");
+            sb.Append("\e_G");
             if (first)
             {
                 sb.Append("a=T,f=100,");
@@ -43,7 +43,7 @@ public string Encode(GraphicPlacement placement)
             sb.Append("m=").Append(last ? '0' : '1');
             sb.Append(';');
             sb.Append(base64, offset, len);
-            sb.Append("\x1b\\");
+            sb.Append("\e\\");
         }
 
         return sb.ToString();

src/Tedd.TUI.Platform.LinuxTerminal/LinuxTerminalPlatform.cs

@@ -101,7 +101,7 @@ public void Initialize()
         try
         {
             // Switch to the alt screen, enable SGR mouse mode, hide the cursor.
-            System.Console.Write("\x1b[?1049h\x1b[?1000h\x1b[?1006h\x1b[?25l");
+            System.Console.Write("\e[?1049h\e[?1000h\e[?1006h\e[?25l");
             _altScreenEntered = true;
         }
         catch { }
@@ -111,7 +111,7 @@ public void Shutdown()
     {
         if (_altScreenEntered)
         {
-            try { System.Console.Write("\x1b[?25h\x1b[?1006l\x1b[?1000l\x1b[?1049l"); } catch { }
+            try { System.Console.Write("\e[?25h\e[?1006l\e[?1000l\e[?1049l"); } catch { }
             _altScreenEntered = false;
         }
 

src/Tedd.TUI.Tests/AnsiTrueColorRendererTests.cs

@@ -20,8 +20,8 @@ public void Render_EmitsTruecolorSgrSequence()
         renderer.Render(buffer);
 
         string output = sw.ToString();
-        Assert.Contains("\x1b[38;2;10;20;30m", output);
-        Assert.Contains("\x1b[48;2;40;50;60m", output);
+        Assert.Contains("\e[38;2;10;20;30m", output);
+        Assert.Contains("\e[48;2;40;50;60m", output);
         Assert.Contains("ABC", output);
     }
 
@@ -69,7 +69,7 @@ public void Render_InvokesImageEncoderForPlacements()
         renderer.Render(buffer);
 
         Assert.Single(recorded);
-        Assert.Contains("\x1b[1;2H", sw.ToString()); // cursor at row 1, col 2 (1-based)
+        Assert.Contains("\e[1;2H", sw.ToString()); // cursor at row 1, col 2 (1-based)
         Assert.Contains("FAKE", sw.ToString());
     }
 

src/Tedd.TUI.Tests/ImageProtocolEncoderTests.cs

@@ -16,8 +16,8 @@ public void SixelEncoder_WrapsPayloadInDecPm()
         var encoder = new SixelEncoder();
         var encoded = encoder.Encode(new GraphicPlacement { CharWidth = 3, CharHeight = 2 });
 
-        Assert.StartsWith("\x1bP", encoded);
-        Assert.EndsWith("\x1b\\", encoded);
+        Assert.StartsWith("\eP", encoded);
+        Assert.EndsWith("\e\\", encoded);
         Assert.Contains("q", encoded);
         Assert.Equal("sixel", encoder.Protocol);
     }
@@ -43,8 +43,8 @@ public void SixelEncoder_EncodesRgbaPixels()
             CharHeight = 1,
         });
 
-        Assert.StartsWith("\x1bP0;1;0q", encoded);
-        Assert.EndsWith("\x1b\\", encoded);
+        Assert.StartsWith("\eP0;1;0q", encoded);
+        Assert.EndsWith("\e\\", encoded);
         // Each used color must declare itself: "#<idx>;2;<r>;<g>;<b>".
         Assert.Matches(@"#\d+;2;100;0;0", encoded); // red
         Assert.Matches(@"#\d+;2;0;100;0", encoded); // green
@@ -78,8 +78,8 @@ public void KittyEncoder_EmitsChunkedBase64()
             CharHeight = 2,
         });
 
-        Assert.StartsWith("\x1b_G", encoded);
-        Assert.EndsWith("\x1b\\", encoded);
+        Assert.StartsWith("\e_G", encoded);
+        Assert.EndsWith("\e\\", encoded);
         Assert.Contains("a=T,f=100", encoded);
         Assert.Contains("c=4", encoded);
         Assert.Contains("r=2", encoded);
@@ -106,7 +106,7 @@ public void ITerm2Encoder_EmitsInlineEscape()
             MediaType = "image/png",
         });
 
-        Assert.StartsWith("\x1b]1337;File=inline=1", encoded);
+        Assert.StartsWith("\e]1337;File=inline=1", encoded);
         Assert.EndsWith("\x07", encoded);
         Assert.Contains("width=10", encoded);
         Assert.Contains("height=5", encoded);

src/Tedd.TUI/AnsiTrueColorRenderer.cs

@@ -147,7 +147,7 @@ private void EmitGraphics(VirtualBuffer buffer)
             // Park the cursor at the placement's top-left cell so terminals that draw
             // images at the current cursor position (Sixel, iTerm2 inline, Kitty default)
             // land in the right spot.
-            sb.Append('\x1b').Append('[').Append(placement.CharY + 1).Append(';').Append(placement.CharX + 1).Append('H');
+            sb.Append('\e').Append('[').Append(placement.CharY + 1).Append(';').Append(placement.CharX + 1).Append('H');
             sb.Append(encoder.Encode(placement));
         }
 
@@ -199,7 +199,7 @@ private void AppendChar(char c)
     private void EmitCursor(int x, int y)
     {
         // ANSI cursor positioning is 1-based.
-        _buffer.Append('\x1b').Append('[').Append(y + 1).Append(';').Append(x + 1).Append('H');
+        _buffer.Append('\e').Append('[').Append(y + 1).Append(';').Append(x + 1).Append('H');
         _cursorX = x;
         _cursorY = y;
     }
@@ -208,12 +208,12 @@ private void EmitColors(TuiColor fg, TuiColor bg)
     {
         if (fg.Packed != _currentFg.Packed)
         {
-            _buffer.Append("\x1b[38;2;").Append(fg.R).Append(';').Append(fg.G).Append(';').Append(fg.B).Append('m');
+            _buffer.Append("\e[38;2;").Append(fg.R).Append(';').Append(fg.G).Append(';').Append(fg.B).Append('m');
             _currentFg = fg;
         }
         if (bg.Packed != _currentBg.Packed)
         {
-            _buffer.Append("\x1b[48;2;").Append(bg.R).Append(';').Append(bg.G).Append(';').Append(bg.B).Append('m');
+            _buffer.Append("\e[48;2;").Append(bg.R).Append(';').Append(bg.G).Append(';').Append(bg.B).Append('m');
             _currentBg = bg;
         }
     }

src/Tedd.TUI/SixelEncoderCore.cs

@@ -73,7 +73,7 @@ public static string EncodePixels(byte[] pixels, int width, int height)
         }
 
         var sb = new StringBuilder(width * height / 6 + 256);
-        sb.Append("\x1bP0;1;0q"); // P2=1 → background pixels remain transparent.
+        sb.Append("\eP0;1;0q"); // P2=1 → background pixels remain transparent.
 
         // Raster attributes: pan=1, pad=1 (square pixels), actual w / h.
         sb.Append('"').Append(1).Append(';').Append(1).Append(';').Append(width).Append(';').Append(height);
@@ -149,7 +149,7 @@ public static string EncodePixels(byte[] pixels, int width, int height)
             }
         }
 
-        sb.Append("\x1b\\");
+        sb.Append("\e\\");
         return sb.ToString();
     }
 
@@ -244,12 +244,12 @@ private static (byte r, byte g, byte b) PaletteRgb(int index)
     private static string EncodePlaceholder(int pxW, int pxH)
     {
         var sb = new StringBuilder(64 + pxW);
-        sb.Append("\x1bP0;0;0q");
+        sb.Append("\eP0;0;0q");
         sb.Append('"').Append(1).Append(';').Append(1).Append(';').Append(pxW).Append(';').Append(pxH);
         sb.Append("#0;2;0;0;0");
         sb.Append('#').Append(0);
         for (int i = 0; i < pxW; i++) sb.Append('?');
-        sb.Append("\x1b\\");
+        sb.Append("\e\\");
         return sb.ToString();
     }
 }