Write GRPH in VSCode using LSP and this extension.
Install the extension from source using npm install.
To run, it needs the GRPH LSP server installed. Clone the compiler from here, and build it using swift build --product LSP (Swift needs to be installed).
You must then set the VSCode setting grph.languageServerPath to {directory where the GRPH compiler was cloned}/.build/debug/LSP (append .exe to that on Windows)