Editor support

Syntax highlighting, a language server, and file-type plumbing for .sumi files. Everything below ships in the sumi repo under editors/.

VS Code

Install the sumi extension from the marketplace, or build it from source:

cd editors/vscode
npm run package          # produces sumi-lang-<version>.vsix
code --install-extension sumi-lang-*.vsix

You get full highlighting: Go inside <script> and {expressions}, CSS inside <style>, and the template’s tags, on*/bind: attributes, and {if}/{for} control tags.

Vim / Neovim

The classic syntax plugin works in both editors with no build step. Add editors/vim to your runtimepath — with lazy.nvim:

{ dir = "/path/to/sumi/editors/vim" }

or copy ftdetect/ and syntax/ into ~/.vim (or ~/.config/nvim). Go and CSS regions use your existing Go/CSS highlighting.

Language server

sumi lsp speaks LSP over stdio and ships with the CLI (brew install tomyan/tap/sumi). It reports parse and validation errors as you type, completes element tags, CSS properties, and component props, shows hover notes for CSS properties, provides document symbols, and jumps to component definitions.

Neovim (with nvim-lspconfig):

vim.api.nvim_create_autocmd("FileType", {
	pattern = "sumi",
	callback = function()
		vim.lsp.start({ name = "sumi", cmd = { "sumi", "lsp" } })
	end,
})

VS Code LSP client wiring is planned for a future extension release; the extension currently ships highlighting only.

The site’s highlighting

gosumi.dev highlights .sumi blocks with the same TextMate grammar via shiki — editors/grammar/sumi.tmLanguage.json is the single source of truth for every consumer.