Editors and Zed

Editors & Zed

croma's editor story is built on two reusable pieces:

• croma-lsp — the stdio Language-Server (diagnostics, formatting, semantic tokens, symbols, folding, hover, completion, code actions).
• tree-sitter-abc — a tree-sitter grammar for ABC 2.1, the reusable syntax asset: one grammar drives highlighting, folding, and structure across many consumers.

The intended user is a developer (musicians use croma's GPUI app, not a code editor) — so this is developer tooling plus a syntax asset reusable far beyond any one editor.

Quick start (Zed)

1. Put the language server on your PATH:

   cargo install --path crates/croma-lsp     # → ~/.cargo/bin/croma-lsp

   (Once binary releases are published, the Zed extension downloads croma-lsp automatically; until then, cargo install is the path.)

2. Dev-install the extension: in Zed, run zed: install dev extension and select editors/zed/. Open any .abc file — highlighting comes from the grammar, and the status bar shows croma-lsp attaching for diagnostics / formatting / hover / completion.

The Zed extension resolves croma-lsp download-or-PATH: a binary on PATH first, then a GitHub-release auto-download per platform, else a clear error.

One grammar, many consumers

Consumer	How
Zed	extension registers the ABC language, wires the grammar, launches croma-lsp
croma's GPUI app	tree-sitter embeds directly (Zed = GPUI; same engine)
Web / browser	tree-sitter build --wasm → loaded by web-tree-sitter; live demo + headless verify.mjs gate
Markdown	```abc fenced-block injection
Neovim / Helix	consume the grammar + queries directly

A TextMate grammar (VS Code) was deliberately not built: it is editor-specific and buys none of this reuse. VS Code is out of scope.

Editor matrix

Editor	Highlighting	LSP	Status
Zed	tree-sitter-abc (native)	croma-lsp (full)	shipped — dev-install
Neovim	tree-sitter-abc	croma-lsp via nvim-lspconfig	grammar + server ready; config snippet deferred
Helix	tree-sitter-abc	croma-lsp via languages.toml	grammar + server ready; config snippet deferred
Browser / GPUI	tree-sitter-abc (WASM)	—	shipped — web demo
VS Code	—	—	out of scope

Grammar coverage

tree-sitter-abc parses the full 10k ABC corpus at 99.46% clean (9,946 / 10,000, no ERROR nodes); the categorized residual is backstopped by croma-lsp semantic tokens.

Full reference

Building the pieces (grammar generate/test/--wasm via wasi-sdk, the Zed extension wasm build, the web demo) and the reuse evidence are in docs/editors.md, tree-sitter-abc/README.md, and editors/zed/README.md.