fix: Resolve repository URL for install/update (registry + install fallbacks)

src/lib/containers/install.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -34,11 +35,14 @@ func InstallContainer(ctx context.Context, item types.RegistryContainer) error {
 	}
 
 	// 2. Fetch raw docker-compose.yaml from the Git URL
-	rawURL := fmt.Sprintf("%s/raw/branch/master/docker-compose.yaml", item.URL)
+	rawURL, err := composeRawURL(item)
+	if err != nil {
+		return fmt.Errorf("failed to resolve repository URL: %w", err)
+	}
 	composePath := filepath.Join(targetDir, "docker-compose.yaml")
 
 	logger.Info("Fetching compose file from %s...", rawURL)
-	if err := downloadFile(ctx, rawURL, composePath); err != nil {
+	if err := downloadCompose(ctx, rawURL, composePath); err != nil {
 		return fmt.Errorf("failed to download docker-compose.yaml: %w", err)
 	}
 
@@ -347,6 +351,37 @@ func getContainerDataDir(serviceName string) (string, error) {
 	return filepath.Join(root, serviceName), nil
 }
 
+// composeRawURL resolves the raw docker-compose.yaml URL for a container,
+// preferring the repository URL in item.URL (falling back to item.Source) and
+// rejecting URLs without an http/https scheme.
+func composeRawURL(item types.RegistryContainer) (string, error) {
+	base := strings.TrimRight(item.URL, "/")
+	if base == "" {
+		base = strings.TrimRight(item.Source, "/")
+	}
+	u, err := url.Parse(base)
+	if err != nil || (u.Scheme != "http" && u.Scheme != "https") {
+		return "", fmt.Errorf("invalid repository URL %q", base)
+	}
+	return fmt.Sprintf("%s/raw/branch/master/docker-compose.yaml", base), nil
+}
+
+// downloadCompose fetches the compose file, retrying on the main branch when
+// the repository's default branch is not master.
+func downloadCompose(ctx context.Context, url, destPath string) error {
+	err := downloadFile(ctx, url, destPath)
+	if err != nil {
+		mainURL := strings.Replace(url, "/raw/branch/master/", "/raw/branch/main/", 1)
+		if mainURL != url {
+			if retryErr := downloadFile(ctx, mainURL, destPath); retryErr == nil {
+				return nil
+			}
+		}
+		return err
+	}
+	return nil
+}
+
 func downloadFile(ctx context.Context, url string, destPath string) error {
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
 	if err != nil {