The most important change included here is the view system in ddd_datasette.py there is a request url router that delegates to python modules in www/templates/views/*.py and then passes the variables from the model to a template with a matching filename (except the extension is html)
So the url /-/ddd/$page loads the python module from
www/templates/views/$page.py
which returns some variables for the view.
Then the variables are passed to a jinja template named
www/templates/views/$page.html
Also, canned queries are now loaded from sql files in www/sql/$db_name/$query_name
Finally, the function sql() can be called from templates and it can reference canned queries
(See extra_template_vars in ddd_datasette.py)