Harden StripTags against stray angle brackets

pipeline.go

@@ -32,7 +32,7 @@ func StripTags(html string) string {
 
 		switch r {
 		case '<':
-			if i+1 < len(runes) && isTagStartRune(runes[i+1]) {
+			if i+1 < len(runes) && isTagStartRune(runes[i+1]) && hasTagCloser(runes, i+2) {
 				inTag = true
 				continue
 			}
@@ -67,6 +67,15 @@ func isTagStartRune(r rune) bool {
 	}
 }
 
+func hasTagCloser(runes []rune, start int) bool {
+	for i := start; i < len(runes); i++ {
+		if runes[i] == '>' {
+			return true
+		}
+	}
+	return false
+}
+
 // Imprint renders a node tree to HTML, strips tags, tokenises the text,
 // and returns a GrammarImprint — the full render-reverse pipeline.
 // Usage example: imp := Imprint(Text("welcome"), NewContext())

pipeline_test.go

@@ -54,6 +54,14 @@ func TestStripTags_PreservesComparisonOperators_Good(t *testing.T) {
 	}
 }
 
+func TestStripTags_LiteralAngleBracket_Good(t *testing.T) {
+	got := StripTags(`a<b`)
+	want := `a<b`
+	if got != want {
+		t.Errorf("StripTags(literal angle) = %q, want %q", got, want)
+	}
+}
+
 func TestStripTags_Entities_Good(t *testing.T) {
 	got := StripTags(`&lt;script&gt;`)
 	want := "&lt;script&gt;"