commit 668a0efbf6591ed7a90298bd8f6c63ad1a783587
Author: Chandler Swift <chandler@chandlerswift.com>
Date:   Sat Aug 30 22:52:35 2025 -0500

    file_server: Implement natural sort for browse templates

diff --git a/modules/caddyhttp/fileserver/browsetplcontext.go b/modules/caddyhttp/fileserver/browsetplcontext.go
index b9489c6a..339eea21 100644
--- a/modules/caddyhttp/fileserver/browsetplcontext.go
+++ b/modules/caddyhttp/fileserver/browsetplcontext.go
@@ -325,11 +325,72 @@ type (
 	byTime         browseTemplateContext
 )
 
+func isDigit(b byte) bool { return '0' <= b && b <= '9' }
+
+// naturalLess compares two strings using natural ordering. This means that e.g.
+// "abc2" < "abc12".
+//
+// Non-digit sequences and numbers are compared separately. The former are
+// compared bytewise, while digits are compared numerically (except that
+// the number of leading zeros is used as a tie-breaker, so e.g. "2" < "02")
+//
+// Limitation: only ASCII digits (0-9) are considered.
+func naturalLess(str1, str2 string) bool {
+	idx1, idx2 := 0, 0
+	for idx1 < len(str1) && idx2 < len(str2) {
+		c1, c2 := str1[idx1], str2[idx2]
+		dig1, dig2 := isDigit(c1), isDigit(c2)
+		switch {
+		case dig1 != dig2: // Digits before other characters.
+			return dig1 // True if LHS is a digit, false if the RHS is one.
+		case !dig1: // && !dig2, because dig1 == dig2
+			// UTF-8 compares bytewise-lexicographically, no need to decode
+			// codepoints.
+			if c1 != c2 {
+				return c1 < c2
+			}
+			idx1++
+			idx2++
+		default: // Digits
+			// Eat zeros.
+			for ; idx1 < len(str1) && str1[idx1] == '0'; idx1++ {
+			}
+			for ; idx2 < len(str2) && str2[idx2] == '0'; idx2++ {
+			}
+			// Eat all digits.
+			nonZero1, nonZero2 := idx1, idx2
+			for ; idx1 < len(str1) && isDigit(str1[idx1]); idx1++ {
+			}
+			for ; idx2 < len(str2) && isDigit(str2[idx2]); idx2++ {
+			}
+			// If lengths of numbers with non-zero prefix differ, the shorter
+			// one is less.
+			if len1, len2 := idx1-nonZero1, idx2-nonZero2; len1 != len2 {
+				return len1 < len2
+			}
+			// If they're equally long, string comparison is correct.
+			if nr1, nr2 := str1[nonZero1:idx1], str2[nonZero2:idx2]; nr1 != nr2 {
+				return nr1 < nr2
+			}
+			// Otherwise, the one with less zeros is less.
+			// Because everything up to the number is equal, comparing the index
+			// after the zeros is sufficient.
+			if nonZero1 != nonZero2 {
+				return nonZero1 < nonZero2
+			}
+		}
+		// They're identical so far, so continue comparing.
+	}
+	// So far they are identical. At least one is ended. If the other continues,
+	// it sorts last.
+	return len(str1) < len(str2)
+}
+
 func (l byName) Len() int      { return len(l.Items) }
 func (l byName) Swap(i, j int) { l.Items[i], l.Items[j] = l.Items[j], l.Items[i] }
 
 func (l byName) Less(i, j int) bool {
-	return strings.ToLower(l.Items[i].Name) < strings.ToLower(l.Items[j].Name)
+	return naturalLess(strings.ToLower(l.Items[i].Name), strings.ToLower(l.Items[j].Name))
 }
 
 func (l byNameDirFirst) Len() int      { return len(l.Items) }
@@ -338,7 +399,7 @@ func (l byNameDirFirst) Swap(i, j int) { l.Items[i], l.Items[j] = l.Items[j], l.
 func (l byNameDirFirst) Less(i, j int) bool {
 	// sort by name if both are dir or file
 	if l.Items[i].IsDir == l.Items[j].IsDir {
-		return strings.ToLower(l.Items[i].Name) < strings.ToLower(l.Items[j].Name)
+		return naturalLess(strings.ToLower(l.Items[i].Name), strings.ToLower(l.Items[j].Name))
 	}
 	// sort dir ahead of file
 	return l.Items[i].IsDir