fix(escape): wrap PUA/Nerd Font icon glyphs with Roboto Mono Nerd Font

Author: Ivan

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 Dates use YYYY-MM-DD.
 
+## [1.1.1] - 2026-09-06
+
+### Fixed
+
+- PUA/Nerd Font icon glyphs are now wrapped in a span with `font-family:'Roboto Mono Nerd Font',monospace` so they render correctly in browser WASM builds instead of falling back to a font that lacks the glyph.
+
 ## [1.1.0] - 2026-09-05
 
 ### Added

micron/escape.go

@@ -6,6 +6,7 @@ package micron
 import (
 	"html"
 	"strings"
+	"unicode/utf8"
 )
 
 // stripASCIIControls removes ASCII control characters (U+0000-U+001F).
@@ -33,32 +34,62 @@ func htmlText(s string) string {
 	return html.EscapeString(stripASCIIControls(s))
 }
 
+// isNerdIconRune returns true for runes in the Private Use Areas that
+// Nerd Font / patched icon fonts occupy. These glyphs need a font that
+// includes them, otherwise they render as replacement boxes.
+func isNerdIconRune(r rune) bool {
+	return (r >= 0xE000 && r <= 0xF8FF) ||
+		(r >= 0xF0000 && r <= 0xFFFFD) ||
+		(r >= 0x100000 && r <= 0x10FFFD)
+}
+
 func appendHTMLText(b *strings.Builder, s string) {
 	s = stripASCIIControls(s)
+	var icon bool
 	start := 0
-	for i := range len(s) {
-		var esc string
-		switch s[i] {
-		case '&':
-			esc = "&amp;"
-		case '<':
-			esc = "&lt;"
-		case '>':
-			esc = "&gt;"
-		case '"':
-			esc = "&#34;"
-		case '\'':
-			esc = "&#39;"
-		default:
-			continue
+	for i := 0; i < len(s); {
+		r, size := utf8.DecodeRuneInString(s[i:])
+		nextIcon := isNerdIconRune(r)
+		if nextIcon != icon {
+			if start < i {
+				b.WriteString(s[start:i])
+			}
+			if nextIcon {
+				b.WriteString(`<span class="nf" style="font-family:'Roboto Mono Nerd Font',monospace">`)
+			} else {
+				b.WriteString(`</span>`)
+			}
+			icon = nextIcon
+			start = i
 		}
-		if start < i {
-			b.WriteString(s[start:i])
+		if !nextIcon && size == 1 {
+			var esc string
+			switch s[i] {
+			case '&':
+				esc = "&amp;"
+			case '<':
+				esc = "&lt;"
+			case '>':
+				esc = "&gt;"
+			case '"':
+				esc = "&#34;"
+			case '\'':
+				esc = "&#39;"
+			}
+			if esc != "" {
+				if start < i {
+					b.WriteString(s[start:i])
+				}
+				b.WriteString(esc)
+				start = i + 1
+			}
 		}
-		b.WriteString(esc)
-		start = i + 1
+		i += size
 	}
 	if start < len(s) {
 		b.WriteString(s[start:])
 	}
+	if icon {
+		b.WriteString(`</span>`)
+	}
 }

micron/html_build.go

@@ -160,7 +160,7 @@ func (p *Parser) writeLink(b *strings.Builder, lk *Link, s *State) {
 		b.WriteString(`"`)
 		appendQuotedHTMLStyleAttr(b, lk.Style, s.DefaultBG)
 		b.WriteString(`>`)
-		b.WriteString(lk.Label)
+		appendHTMLText(b, lk.Label)
 		b.WriteString(`</a>`)
 		return
 	}
@@ -207,7 +207,7 @@ func (p *Parser) writeLink(b *strings.Builder, lk *Link, s *State) {
 	b.WriteString(`"`)
 	appendQuotedHTMLStyleAttr(b, lk.Style, s.DefaultBG)
 	b.WriteString(`>`)
-	b.WriteString(lk.Label)
+	appendHTMLText(b, lk.Label)
 	b.WriteString(`</a>`)
 }