I have started work on building a complete map of the build website, called the Structure.
It occurs to me that that my program flow is wrong - I shouldn't go to from source to HTML to template immediately. If I am to build navigation into the final web pages, that will happen at the handlebars stage, but only once the full site structure is known. Working on generating that json now.
Getting close to needing a UI.
It's just occurred to me that storing temporary files in the source bucket might not be a good idea, because FileUploadManager may get into a loop responding to the very files it and MarkdownProcessorHandler create? I may need a third, temporary bucket. At the very least, the FileUploadManager will be triggered unnecessarily. Though the final destination bucket, in theory, is out of scope of this project - hypothetically, if this were a sellable service, the customer could provide their down destination bucket?