Feature request: syntax-highlighting in Notebook output cells for extension-contributed custom-language grammars with text/x-mylanguageid #223460
Description
As of today, authors of custom NotebookControllers/NotebookSerializers already can produce Notebook output cells as syntax-highlighted code in one of a predefined hardcoded set of supported languages only.
So if you're outputting data structures pretty-printed/syntaxed in a custom language your extension serves (with a grammar and LSP / IntelliSense), you'll have to pick one of that above-linked listing of predefined text/x-languageids that comes closest to your syntax , or the one that "messes it up the least".
The idea of this feature request: just like Notebook input cells can already, today fully benefit from extension-contributed custom-language IntelliSense and syntax-highlighting of their own extension-contributed language grammars, so should the output cell syntax-highlighting also support any language grammar registered with VSCode (whether built-in or extension-provided), not just the above-linked "blessed predefined hardcoded set" of them.
Previous discussion motivating the feature request here, CC @rebornix