Oh, I didn’t read the filter docs before I’ve posted my comment. Somehow I thought React can only be used on client, whereas in reality what happens on client is not finch’s concern at all. My bad.
And of course, you’re right that rehydrating requires renderToString, not renderToStaticMarkup.
As for SSR with React, you’re right that it’s mostly used with a Node server and most probably involves numerous DB queries. In most of the cases those queries are initiated by the components independently (during render), which is good for the app maintainability, but begets a hard problem of how to tell when all of the data for the page is there. So it’s probably way beyond the scope of generating html files from markdown or json.
By the way, I thought of adding React to my statically-built site hosted on Netlify (haven’t move beyond converting the templates from Pug to ReasonReact though), and I think that if you want a lib like React, you probably do want an SPA, and so to navigate to another page without a page reload, you would at least need a json with that page’s model (probably put next to that page’s index.html. But I haven’t really thought this through. Like how you tell the page template just by a link? Maybe you need to put it in the page model too. Etc.