Assigning template language to html files based on presence of framework

I am writing a plugin that interprets template expressions in html files: https://plugins.jetbrains.com/plugin/10021-svelte

I've been able to parse template expressions using MultiplePsiFilesPerDocumentFileViewProvider in html files containing elements of the template language, by defining a SvelteFileType and applying it to files with the html extension. I can also define a svelte framework and let the user activate it manually (might also be detected automatically based on package.json, but that is a different story). Two questions:

• how can I find out if the svelte framework is active for the current project from within the FileTypeFactory, so that I do not activate the svelte parser in html files of all projects, but only in svelte projects? The way described in the faq with getDataContextFromFocus does not work, I get a datacontext, but the project is null in the FileTypeFactory:

DataContext dataContext =
    DataManager.getInstance().getDataContextFromFocus().getResult();
Project project = DataKeys.PROJECT.getData(dataContext);

In the ui I see that the project is still being loaded when my FileTypeFactory is called, so probably there is really no project at that time. Or can I redefine the language of an html file later, after the project exists, so that my MultiplePsiFilesPerDocumentFileViewProvider kicks in?

• Assuming that I have the current project: How do I find out if my framework is present on the project?