another fix

backend/cmd/server/main.go

@@ -80,6 +80,7 @@ func main() {
 	downloadHandler := downloads.NewHandler(galleryRepository, mediaRepository, objectStorage, authService, downloadService)
 	devHandler := devtools.NewHandler(database, objectStorage, authService, devtools.Config{
 		DBDriver:        cfg.DBDriver,
+		APIURL:          cfg.APIURL,
 		StorageEndpoint: cfg.StorageEndpoint,
 		StorageBucket:   cfg.StorageBucket,
 		StorageUseSSL:   cfg.StorageUseSSL,
@@ -113,7 +114,11 @@ func main() {
 	}
 
 	go func() {
-		log.Printf("API listening on http://localhost%s", server.Addr)
+		addr := cfg.APIURL
+		if addr == "" {
+			addr = "http://localhost" + server.Addr
+		}
+		log.Printf("API listening on %s", addr)
 		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
 			log.Fatalf("server failed: %v", err)
 		}

backend/internal/dev/handler.go

@@ -17,6 +17,7 @@ import (
 
 type Config struct {
 	DBDriver        string
+	APIURL          string
 	StorageEndpoint string
 	StorageBucket   string
 	StorageUseSSL   bool
@@ -67,6 +68,7 @@ func (h *Handler) Diagnostics(c *gin.Context) {
 	writeJSON(c, http.StatusOK, map[string]any{
 		"environment": "development",
 		"now":         time.Now().UTC().Format(time.RFC3339),
+		"url":         h.config.APIURL,
 		"user": map[string]string{
 			"id":    user.ID.String(),
 			"email": user.Email,