If no namespace is specified in the <templatestyles> tag src attribute, the extension defaults to the Template namespace through this line in TemplateStylesHooks.php:

$title = Title::newFromText( $params['src'], NS_TEMPLATE );

We are storing all template styles in a TemplateStyle namespace and would like that to be the default, so we've hacked this line to modify the namespace.

Some of our reasons for doing it this way are for organization, so the template CSS subpages don't show up using LinkSuggest, and to be able to apply namespace-level editing restrictions to the template CSS.

It would be beneficial if the default namespace could be a configuration option instead, so we don't have to modify the extension after every update.