URL-encode path segments to fix pound sign in filenames

internal/common/utils.go

@@ -1,8 +1,10 @@
 package common
 
 import (
+	"net/url"
 	"path"
 	"reflect"
+	"strings"
 	"time"
 )
 
@@ -18,7 +20,14 @@ func PrettyTime(t time.Time) string {
 
 // CanonicalURL returns a canonical URL for the given path.
 func CanonicalURL(isDir bool, p ...string) string {
-	s := path.Join(p...)
+	// URL-encode each path segment so that special characters like '#'
+	// are properly escaped (e.g. '#' becomes '%23').
+	joined := path.Join(p...)
+	segments := strings.Split(joined, "/")
+	for i, seg := range segments {
+		segments[i] = url.PathEscape(seg)
+	}
+	s := strings.Join(segments, "/")
 
 	if isDir {
 		s += "/"

internal/common/utils_test.go

@@ -0,0 +1,96 @@
+package common
+
+import (
+	"testing"
+)
+
+func TestCanonicalURL(t *testing.T) {
+	tests := []struct {
+		name   string
+		isDir  bool
+		parts  []string
+		expect string
+	}{
+		{
+			name:   "simple file",
+			isDir:  false,
+			parts:  []string{"/files", "readme.txt"},
+			expect: "/files/readme.txt",
+		},
+		{
+			name:   "simple directory",
+			isDir:  true,
+			parts:  []string{"/files", "subdir"},
+			expect: "/files/subdir/",
+		},
+		{
+			name:   "pound sign in filename",
+			isDir:  false,
+			parts:  []string{"/files", "track#1.mp3"},
+			expect: "/files/track%231.mp3",
+		},
+		{
+			name:   "pound sign in directory",
+			isDir:  true,
+			parts:  []string{"/files", "C# Projects"},
+			expect: "/files/C%23%20Projects/",
+		},
+		{
+			name:   "space in filename",
+			isDir:  false,
+			parts:  []string{"/files", "my file.txt"},
+			expect: "/files/my%20file.txt",
+		},
+		{
+			name:   "question mark in filename",
+			isDir:  false,
+			parts:  []string{"/files", "what?.txt"},
+			expect: "/files/what%3F.txt",
+		},
+		{
+			name:   "percent in filename",
+			isDir:  false,
+			parts:  []string{"/files", "100%.txt"},
+			expect: "/files/100%25.txt",
+		},
+		{
+			name:   "multiple special chars",
+			isDir:  false,
+			parts:  []string{"/docs", "file #2 (copy).txt"},
+			expect: "/docs/file%20%232%20%28copy%29.txt",
+		},
+		{
+			name:   "nested path with pound",
+			isDir:  false,
+			parts:  []string{"/music", "artist#name", "track#1.mp3"},
+			expect: "/music/artist%23name/track%231.mp3",
+		},
+		{
+			name:   "root directory file",
+			isDir:  false,
+			parts:  []string{"/", "file.txt"},
+			expect: "/file.txt",
+		},
+		{
+			name:   "single segment file",
+			isDir:  false,
+			parts:  []string{"file.txt"},
+			expect: "file.txt",
+		},
+		{
+			name:   "no special chars",
+			isDir:  false,
+			parts:  []string{"/path", "to", "file.txt"},
+			expect: "/path/to/file.txt",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := CanonicalURL(tt.isDir, tt.parts...)
+			if got != tt.expect {
+				t.Errorf("CanonicalURL(%v, %v) = %q, want %q", tt.isDir, tt.parts, got, tt.expect)
+			}
+		})
+	}
+}