Very nice work. I look forward to seeing where they go with this. I am curious as to how they handle polygons that span multiple tiles. If they take the rather straightforward approach of taking any polygon and splitting it up to fit in each respective tile, that has all sorts of implications for styling. Imagine you want to draw a building as a solid color and then draw the outline in some secondary color. What happens if the building falls on a tile boundary?
Without having looked at this implementation (but I know a startup doing something similar for an internal system): You add a suitably sized "buffer". So e.g. if your maximum stroke width is 20, you clip the polygon with an accordingly large margin. There are still potential caveats, e.g. if you want to allow changing automated label placement based on shapes etc., but the potential win is still massive even if you have to put some minor restrictions on what type of restyling can be done without having to "re-render" into vector tiles - this way at least most typical restyling such as changing colours or stroke widths can be done trivially.
