Preflight report output filenames

internal/app/output.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"gitea.maximumdirect.net/eric/weatherreporter/internal/comparison"
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/fileutil"
 	"gitea.maximumdirect.net/eric/weatherreporter/internal/report"
 )
 
@@ -184,6 +185,9 @@ func validateOutputPath(path string) (string, error) {
 	if filepath.Dir(path) == path {
 		return "", fmt.Errorf("final output path %q must not be a filesystem root", path)
 	}
+	if err := fileutil.ValidateAtomicPath(path); err != nil {
+		return "", fmt.Errorf("validate final output path %q: %w", path, err)
+	}
 	if info, err := os.Stat(path); err == nil && info.IsDir() {
 		return "", fmt.Errorf("final output path %q is a directory", path)
 	} else if err != nil && !os.IsNotExist(err) {