fix: correct Unicode 16.0 width mismatch for ☰ (U+2630) and 85 other codepoints

Wcwidth library defaults to Unicode 16.0 tables where trigrams (U+2630-2637),
hexagrams (U+4DC0-4DFF), and others were reclassified from width 1 to 2.
No terminals have adopted these new widths yet, causing layout misalignment.

Pin UnicodeWidth to Unicode 15.0 tables by default and add a terminal probe
that detects Unicode 16.0 width support at startup, auto-switching when
terminals catch up.

Author: nickprotop

SharpConsoleUI/Helpers/TerminalCapabilities.cs

@@ -15,6 +15,7 @@ namespace SharpConsoleUI.Helpers
 	public static class TerminalCapabilities
 	{
 		private static bool? _supportsVS16Widening;
+		private static bool? _supportsUnicode16Widths;
 
 		/// <summary>
 		/// Whether the terminal renders emoji+VS16 (U+FE0F) as 2 columns.
@@ -27,8 +28,19 @@ public static bool SupportsVS16Widening
 		}
 
 		/// <summary>
-		/// Probes the terminal to determine if VS16 (U+FE0F) widens emoji.
-		/// Writes a test character, queries cursor position via DSR, and compares.
+		/// Whether the terminal renders Unicode 16.0 newly-widened characters
+		/// (e.g. U+2630 ☰ trigrams) as 2 columns.
+		/// When false, these characters are treated as width 1 (Unicode 15.0 behavior).
+		/// Defaults to false (most terminals haven't adopted Unicode 16.0 widths yet).
+		/// </summary>
+		public static bool SupportsUnicode16Widths
+		{
+			get => _supportsUnicode16Widths ?? false;
+		}
+
+		/// <summary>
+		/// Probes the terminal to determine rendering capabilities.
+		/// Tests VS16 emoji widening and Unicode 16.0 width changes.
 		/// Must be called after raw mode is entered and before input loops start.
 		/// </summary>
 		/// <param name="write">Action to write escape sequences to the terminal.</param>
@@ -45,6 +57,16 @@ public static void Probe(Action<string> write, Func<int> readByte)
 				// If probing fails, assume modern terminal
 				_supportsVS16Widening = true;
 			}
+
+			try
+			{
+				_supportsUnicode16Widths = ProbeUnicode16Width(write, readByte);
+			}
+			catch
+			{
+				// If probing fails, assume terminal hasn't adopted Unicode 16.0 widths
+				_supportsUnicode16Widths = false;
+			}
 		}
 
 		/// <summary>
@@ -56,12 +78,22 @@ public static void SetVS16Widening(bool supported)
 			_supportsVS16Widening = supported;
 		}
 
+		/// <summary>
+		/// Allows manual override of the Unicode 16.0 width capability.
+		/// Useful for testing or when the terminal is known ahead of time.
+		/// </summary>
+		public static void SetUnicode16Widths(bool supported)
+		{
+			_supportsUnicode16Widths = supported;
+		}
+
 		/// <summary>
 		/// Resets all cached capabilities (for testing).
 		/// </summary>
 		internal static void Reset()
 		{
 			_supportsVS16Widening = null;
+			_supportsUnicode16Widths = null;
 		}
 
 		private static bool ProbeVS16(Action<string> write, Func<int> readByte)
@@ -90,6 +122,28 @@ private static bool ProbeVS16(Action<string> write, Func<int> readByte)
 			return col >= 3; // col is 1-based; 3 means cursor at column 3 → char was 2 wide
 		}
 
+		/// <summary>
+		/// Probes whether the terminal renders Unicode 16.0 newly-widened characters as 2 columns.
+		/// Tests U+2630 (☰ TRIGRAM FOR HEAVEN), which changed from width 1 to 2 in Unicode 16.0.
+		/// </summary>
+		private static bool ProbeUnicode16Width(Action<string> write, Func<int> readByte)
+		{
+			// Write ☰ (U+2630) and query cursor position.
+			// Unicode 15.0: width 1 → cursor at column 2
+			// Unicode 16.0: width 2 → cursor at column 3
+			write("\r\u2630\x1b[6n");
+
+			int col = ReadDSRColumn(readByte);
+
+			// Clean up probe output
+			write("\r\x1b[K");
+
+			if (col < 0)
+				return false; // Timeout/error → assume pre-Unicode 16.0
+
+			return col >= 3; // col 3 means 2-wide rendering (Unicode 16.0)
+		}
+
 		/// <summary>
 		/// Reads a DSR (Device Status Report) response and extracts the column number.
 		/// Expected format: ESC [ row ; col R

SharpConsoleUI/Helpers/UnicodeWidth.cs

@@ -18,16 +18,28 @@ namespace SharpConsoleUI.Helpers
 	/// including zero-width characters (combining marks, variation selectors, ZWJ).
 	/// Spacing Combining Marks (Unicode category Mc) are corrected to width 1,
 	/// as they occupy visual space in terminals despite Wcwidth marking them zero-width.
+	/// Adapts to terminal capabilities: uses Unicode 15.0 width tables unless the
+	/// terminal is detected to support Unicode 16.0 widths (probed at startup).
 	/// </summary>
 	public static class UnicodeWidth
 	{
+		/// <summary>
+		/// Returns the Wcwidth Unicode version to use based on terminal capabilities.
+		/// Unicode 16.0 widened 86 codepoints (trigrams U+2630-2637, hexagrams U+4DC0-4DFF, etc.)
+		/// from 1 to 2 columns. Most terminals haven't adopted this yet, so we default to 15.0.
+		/// </summary>
+		private static Unicode EffectiveUnicodeVersion
+			=> TerminalCapabilities.SupportsUnicode16Widths
+				? Unicode.Version_16_0_0
+				: Unicode.Version_15_0_0;
+
 		/// <summary>
 		/// Returns the display width of a character in terminal columns (0, 1, or 2).
 		/// Spacing Combining Marks (Mc) are corrected to width 1.
 		/// </summary>
 		public static int GetCharWidth(char c)
 		{
-			int w = UnicodeCalculator.GetWidth(c);
+			int w = UnicodeCalculator.GetWidth(c, EffectiveUnicodeVersion);
 			if (w <= 0)
 			{
 				// Spacing Combining Marks (Mc) occupy visual space in terminals
@@ -44,7 +56,7 @@ public static int GetCharWidth(char c)
 		/// </summary>
 		public static int GetRuneWidth(Rune r)
 		{
-			int w = UnicodeCalculator.GetWidth(r.Value);
+			int w = UnicodeCalculator.GetWidth(r.Value, EffectiveUnicodeVersion);
 			if (w <= 0)
 			{
 				// Spacing Combining Marks (Mc) occupy visual space in terminals