feat: multi-feature update

common/embed-file-system.go

@@ -5,6 +5,7 @@ import (
 	"io/fs"
 	"net/http"
 	"os"
+	"strings"
 
 	"github.com/gin-contrib/static"
 )
@@ -16,7 +17,17 @@ type embedFileSystem struct {
 }
 
 func (e *embedFileSystem) Exists(prefix string, path string) bool {
-	_, err := e.Open(path)
+	// gin-contrib/static passes the raw URL path (e.g. "/image-gen/assets/x.js")
+	// together with the URL prefix we registered (e.g. "/image-gen"). The
+	// underlying fs.Sub FS only knows about the sub-tree (no prefix), so we
+	// must strip the prefix before asking it whether the file exists. An
+	// empty prefix means "served at /" — nothing to strip.
+	p := strings.TrimPrefix(path, prefix)
+	if p == path {
+		// prefix didn't match — definitely not in this FS
+		return false
+	}
+	_, err := e.Open(p)
 	if err != nil {
 		return false
 	}