fix: tag parsing truncates emojis with variation selectors (#5496)

plugin/markdown/parser/tag.go

@@ -47,6 +47,17 @@ func isValidTagRune(r rune) bool {
 		return true
 	}
 
+	// Allow marks (non-spacing, spacing combining, enclosing)
+	// This covers variation selectors (e.g. VS16 \uFE0F) and combining marks (e.g. Keycap \u20E3, accents)
+	if unicode.IsMark(r) {
+		return true
+	}
+
+	// Allow Zero Width Joiner (ZWJ) for emoji sequences
+	if r == '\u200D' {
+		return true
+	}
+
 	// Allow specific ASCII symbols for tag structure
 	// Underscore: word separation (snake_case)
 	// Hyphen: word separation (kebab-case)

plugin/markdown/parser/tag_test.go

@@ -174,6 +174,18 @@ func TestTagParser(t *testing.T) {
 			expectedTag: "test🚀",
 			shouldParse: true,
 		},
+		{
+			name:        "emoji with VS16",
+			input:       "#test👁️", // Eye + VS16
+			expectedTag: "test👁️",
+			shouldParse: true,
+		},
+		{
+			name:        "emoji with ZWJ sequence",
+			input:       "#family👨‍👩‍👧‍👦", // Family ZWJ sequence
+			expectedTag: "family👨‍👩‍👧‍👦",
+			shouldParse: true,
+		},
 	}
 
 	for _, tt := range tests {