> How about a treesitter-based editor extension that converts between begin/end and {/}, as if they were ligatures? Actually this might not even need treesitter.

See emacs prettify-symbols-mode (https://emacs.stackexchange.com/questions/46529/configuring-...)

I'd rather have systematic "language skinning", where different flavors (begin and end versus { and }) are isomorphisms of each other so one's tooling can fluidly translate between both forms.

Rochus is almost kind of doing this with Oberon+ versus Wirthian Oberon already, but it would be nice to go further.

> How about a treesitter-based editor extension that converts between begin/end and {/}, as if they were ligatures? Actually this might not even need treesitter.

Neovim has the conceal feature, which can convert Treesitter nodes into a single symbol, but not the other way around unfortunately.