We tend to recommend client-blocks because it's intrinsic to how the editor is meant to work: direct manipulation with instant feedback for all manipulations, which we can only ensure properly client side. ServerSideRender should generally be avoided outside of very naive cases that won't require much interaction or are supposed to work as embeds (tag cloud comes to mind). I would probably not recommend it for the pages block because the moment we start supporting broader customization tools (typography, colors, sizing, possibly reordering, etc) the roundtrip becomes a hindrance to the UX. Server-side blocks are also not well-suited for the mobile apps.

What if one day we would have React Server Components implemented in PHP? 😄

I guess it's far in the future to see it enabled in React, but they are working on the serialization layer so, in theory, it could work with any language. As far as I understood the idea, it would address most of the concerns with the code duplication between Edit in JS and save in PHP. The use case for the mobile apps is probably more difficult to address though.

The streaming protocol would indeed be cool to explore given we already have the block abstraction established. It wouldn't be too out there to consider passing component state through it. We briefly discussed this with @luisherranz in the context of Frontity and how it could consume blocks in the front-end in the future.

But that also points to another important distinction of server-client, which is edit() is meant to tailor its component for editing / interaction while server || save() is meant to render the best representation for the front-end. We don't have the concept of edit on the server.

But that also points to another important distinction of server-client, which is edit() is meant to tailor its component for editing / interaction while server || save() is meant to render the best representation for the front-end. We don't have the concept of edit on the server.

This is a good reminder. It's easy to fall into a trap of wanting to share code between edit and save. We often see reports that React hooks don't work with save on the client. This is a good thing as it helps to understand that save isn't interactive and only translates components into HTML output. It's all interesting, but also extremely hard to communicate to the folks writing blocks.