Handle emoji selector (variant selector 16)

.gitignore

@@ -349,3 +349,5 @@ MigrationBackup/
 # Ionide (cross platform F# VS Code tools) working folder
 .ionide/
 coverage.opencover.xml
+
+history-file

src/PrettyPrompt/Documents/WordWrapping.cs

@@ -47,11 +47,12 @@ public static WordWrappedText WrapEditableCharacters(ReadOnlyStringBuilder input
                 bool isCursorPastCharacter = caret > textIndex;
 
                 Debug.Assert(character != '\t', "tabs should be replaced by spaces");
-                // Zero-width scalars (combining marks, zero-width joiners, variation selectors, etc.) are
-                // legitimate input - e.g. when pasting an emoji such as 🤦🏼‍♂️. They contribute no display
-                // width (so they don't grow the line or trigger wrapping), but they ARE part of the
-                // string/line content, so they must still advance textIndex (the string index) and the
-                // caret column just like any other character. See issue #270.
+                // Zero-width scalars (combining marks, zero-width joiners, etc.) are legitimate input - e.g.
+                // when pasting an emoji such as 🤦🏼‍♂️. They contribute no display width (so they don't grow the
+                // line or trigger wrapping), but they ARE part of the string/line content, so they must still
+                // advance textIndex (the string index) and the caret column just like any other character.
+                // (The emoji variation selector U+FE0F is the exception: GetWidth gives it one column, because
+                // it promotes its base to a 2-column emoji - see UnicodeWidth.) See issue #270.
                 int unicodeWidth = UnicodeWidth.GetWidth(character);
                 currentLineLength += unicodeWidth;
                 textIndex++;

src/PrettyPrompt/Rendering/UnicodeWidth.cs

@@ -38,6 +38,9 @@ public static int GetWidth(char character)
     {
         if (character == '\n') return 1; // PrettyPrompt: treat newline as occupying a single column.
         if (char.IsSurrogate(character)) return 1; // half of a surrogate pair; the pair sums to the scalar's width.
+        // U+FE0F (emoji variation selector) carries the column its base gains from emoji presentation - e.g.
+        // ⚠ (1 col) + VS16 = a 2-col emoji - keeping this per-char sum equal to GetGraphemeClusterWidth.
+        if (character == (char)0xFE0F) return 1;
         return Clamp(UnicodeCalculator.GetWidth(character));
     }
 
@@ -70,6 +73,10 @@ public static int GetGraphemeClusterWidth(ReadOnlySpan<char> cluster)
             return 1; // ill-formed (e.g. a lone surrogate); be defensive and reserve a single column.
         }
         if (baseRune.Value == '\n') return 1;
+        // U+FE0F (emoji variation selector) forces emoji presentation, which is 2 columns even for a base
+        // that defaults to 1 - e.g. ⚠ (U+26A0) is 1 column but ⚠️ is a 2-column emoji; wcwidth misses this.
+        // The length check skips a lone, base-less selector (no width of its own).
+        if (cluster.Length > 1 && cluster.Contains((char)0xFE0F)) return 2;
         return Clamp(UnicodeCalculator.GetWidth(baseRune));
     }
 

tests/PrettyPrompt.Tests/UnicodeWidthTests.cs

@@ -37,6 +37,14 @@ public class UnicodeWidthTests
 
     // narrow supplementary glyph that the old code mis-sized (issue called this out): a playing card is 1
     [InlineData("\U0001F0A1", 1)]                                 // 🂡 playing card ace of spades
+
+    // U+FE0F (emoji variation selector) promotes a default-text base into a two-column emoji. The bare base
+    // is one column, but base + VS16 renders as a 2-column emoji in terminals, so the caret/cursor must size
+    // it as two columns to stay aligned past it. See https://github.com/waf/PrettyPrompt/issues/270.
+    [InlineData("⚠", 1)]                                     // ⚠ warning sign, text presentation = 1 column
+    [InlineData("⚠️", 2)]                               // ⚠️ warning sign + VS16, emoji presentation = 2 columns
+    [InlineData("abc⚠️def", 8)]                         // surrounded: abc (3) + ⚠️ (2) + def (3)
+    [InlineData("ℹ️", 2)]                               // ℹ️ information source + VS16
     public void GetWidth_ReturnsExpectedDisplayWidth(string text, int expectedWidth)
     {
         Assert.Equal(expectedWidth, UnicodeWidth.GetWidth(text));
@@ -50,6 +58,8 @@ public void GetWidth_ReturnsExpectedDisplayWidth(string text, int expectedWidth)
     [InlineData("\u79B0\U000E0100", 2)]                           // 禰󠄀
     [InlineData("a", 1)]                                          // narrow
     [InlineData("\u4E66", 2)]                                     // 书 wide
+    [InlineData("⚠", 1)]                                        // ⚠ warning sign on its own = text presentation, 1 column
+    [InlineData("⚠️", 2)]                                        // ⚠️ warning sign + VS16 = emoji presentation, 2 columns
     public void GetGraphemeClusterWidth_IsCappedAtTwo(string cluster, int expectedWidth)
     {
         Assert.Equal(expectedWidth, UnicodeWidth.GetGraphemeClusterWidth(cluster));

tests/PrettyPrompt.Tests/WordWrappingTests.cs

@@ -66,6 +66,24 @@ public void WrapEditableCharacters_DoubleWidthCharactersWithWrappingInMiddleOfCh
 
     }
 
+    [Fact]
+    public void WrapEditableCharacters_EmojiVariationSelectorAtBoundary_OccupiesTwoColumns()
+    {
+        // ⚠️ (U+26A0 U+FE0F) is a 2-column emoji. With width 6, "abcd" (4 cols) + ⚠️ (2 cols) must exactly
+        // fill the first line - the selector is NOT zero-width here - so "efgh" wraps to the next line.
+        var text = "abcd⚠️efgh";
+        var wrapped = WordWrapping.WrapEditableCharacters(new StringBuilder(text), caret: 0, width: 6);
+
+        Assert.Equal(
+            new[]
+            {
+                new WrappedLine(0, "abcd⚠️"),
+                new WrappedLine(6, "efgh"),
+            },
+            wrapped.WrappedLines
+        );
+    }
+
     [Fact]
     public void WrapWords_GivenLongText_WrapsWords()
     {