I just thought, for colouring we can always simply turn off the Scintilla lexer (set NULL) and pass the [messages](https://www.scintilla.org/ScintillaDoc.html#SCN_STYLENEEDED) to the LSP.
You can't live without Scintilla coloring - ultimately it will always be Scintilla that colors the document. LSP protocol (but not all LSP server implementations) offers semantic tokens
https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17...
but they only tell you that a range in the document is say a class name but how that class is visualised is up to the client (and Scintilla in our case).
And this will be one of the last things I'm going to implement anyway :-P.