Language Support

June 4, 2026 · View on GitHub

Install reference

Language	Server	Install
TypeScript / JavaScript	`typescript-language-server`	`npm i -g typescript-language-server typescript`
Python	`pyright-langserver`	`npm i -g pyright`
Go	`gopls`	`go install golang.org/x/tools/gopls@latest`
Rust	`rust-analyzer`	`rustup component add rust-analyzer`
C / C++	`clangd`	`apt install clangd` / `brew install llvm`
Ruby	`solargraph`	`gem install solargraph`
PHP	`intelephense`	`npm i -g intelephense`
Java	`jdtls`	eclipse.jdt.ls snapshots
YAML	`yaml-language-server`	`npm i -g yaml-language-server`
JSON	`vscode-json-language-server`	`npm i -g vscode-langservers-extracted`
Dockerfile	`docker-langserver`	`npm i -g dockerfile-language-server-nodejs`
C#	`csharp-ls`	`dotnet tool install -g csharp-ls`
Kotlin	`kotlin-language-server`	GitHub releases
Lua	`lua-language-server`	GitHub releases
Swift	`sourcekit-lsp`	Ships with Xcode / Swift toolchain
Zig	`zls`	GitHub releases (match Zig version)
CSS	`vscode-css-language-server`	`npm i -g vscode-langservers-extracted`
HTML	`vscode-html-language-server`	`npm i -g vscode-langservers-extracted`
Terraform	`terraform-ls`	releases.hashicorp.com
Scala	`metals`	`cs install metals` (Coursier)
Gleam	`gleam` (built-in)	GitHub releases
Elixir	`elixir-ls`	GitHub releases
Prisma	`prisma-language-server`	`npm i -g @prisma/language-server`
SQL	`sqls`	`go install github.com/sqls-server/sqls@latest`
Clojure	`clojure-lsp`	GitHub releases
Nix	`nil`	GitHub releases
Dart	`dart language-server`	Ships with Dart SDK (`brew install dart`)
MongoDB	`mongodb-language-server`	`npm i -g @mongodb-js/mongodb-language-server`

CI tool coverage matrix

Tier 1 (start_lsp, open_document, get_diagnostics, inspect_symbol) verified for all 30 languages. Tier 2: 34 additional tools.

Language	Tier 1	symbols	definition	references	completions	workspace	format	declaration	type_hierarchy	hover	call_hier	sem_tok	sig_help
TypeScript	pass	pass	pass	pass	pass	pass	pass	pass	—	pass	pass	pass	pass
Python	pass	pass	pass	pass	pass	pass	—	—	—	pass	pass	pass	—
Go	pass	pass	pass	pass	pass	pass	pass	—	—	pass	pass	pass	pass
Rust	pass	pass	pass	pass	pass	pass	pass	—	—	pass	pass	pass	—
Java	pass	—	—	—	—	—	—	—	pass	pass	pass	—	—
C	pass	pass	pass	pass	pass	pass	pass	pass	—	pass	pass	pass	—
PHP	pass	pass	pass	pass	pass	pass	—	—	—	pass	pass	pass	pass
C++	pass	pass	pass	pass	pass	pass	pass	pass	—	pass	pass	pass	—
JavaScript	pass	pass	pass	pass	pass	pass	pass	pass	—	pass	pass	pass	—
Ruby	pass	pass	pass	pass	pass	pass	pass	—	—	pass	pass	pass	pass
YAML	pass	—	—	—	pass	pass	pass	—	—	pass	—	—	—
JSON	pass	—	—	—	pass	pass	pass	—	—	pass	—	—	—
Dockerfile	pass	—	—	—	pass	pass	—	—	—	pass	—	—	—
C#	pass	pass	pass	pass	pass	pass	pass	—	—	pass	pass	pass	pass
Kotlin	pass	pass	pass	pass	pass	pass	pass	—	—	pass	pass	pass	pass
Lua	pass	pass	—	—	pass	pass	pass	—	—	pass	pass	pass	pass
Swift	pass	pass	pass	pass	pass	pass	pass	—	—	pass	—	pass	—
Zig	pass	pass	pass	pass	pass	fail	pass	—	—	pass	—	pass	pass
CSS	pass	pass	—	—	pass	pass	pass	—	—	pass	—	—	—
HTML	pass	—	—	—	pass	pass	pass	—	—	pass	—	—	—
Terraform	pass	pass	pass	—	pass	pass	pass	—	—	pass	—	—	—
Scala	pass	pass	pass	pass	pass	pass	pass	—	—	pass	—	pass	—
Gleam	pass	pass	pass	pass	pass	fail	pass	—	—	pass	—	—	—
Elixir	pass	fail	pass	pass	pass	pass	pass	—	—	pass	pass	—	pass
Prisma	pass	pass	pass	pass	—	—	pass	—	—	pass	—	—	—
SQL	pass	pass	pass	pass	pass	pass	—	—	—	pass	—	—	—
Clojure	pass	pass	pass	pass	pass	pass	pass	—	—	pass	—	—	—
Nix	pass	pass	—	—	pass	pass	—	—	—	pass	—	—	—
Dart	pass	pass	pass	pass	pass	pass	pass	—	—	pass	—	—	—
MongoDB	pass	—	—	—	pass	pass	—	—	—	pass	—	—	—

See ci-notes.md for per-language CI quirks.

Current (30 languages, CI-tested)

stable = all Tier 1 tools pass CI. experimental = server works but CI results are informational.

Language	Language Server	Status
TypeScript	typescript-language-server	stable
Python	pyright-langserver	stable
Go	gopls	stable
Rust	rust-analyzer	stable
Java	jdtls	flaky (cold-start indexing)
C	clangd	stable
PHP	intelephense	stable
C++	clangd	stable
JavaScript	typescript-language-server	stable
Ruby	solargraph	stable
YAML	yaml-language-server	stable
JSON	vscode-json-language-server	stable
Dockerfile	docker-langserver	stable
C#	csharp-ls	stable
Kotlin	kotlin-language-server	stable
Lua	lua-language-server	stable
Swift	sourcekit-lsp	stable (macos-latest runner)
Zig	zls	stable
CSS	vscode-css-language-server	stable
HTML	vscode-html-language-server	stable
Terraform	terraform-ls	stable
Scala	metals	experimental
Gleam	gleam (built-in lsp)	stable
Elixir	elixir-ls	experimental
Prisma	prisma-language-server	experimental
SQL	sqls	stable (postgres:16 service container)
Clojure	clojure-lsp	stable
Nix	nil	experimental
Dart	dart language-server	stable
MongoDB	mongodb-language-server	experimental

CI job structure

Job	Languages	Runner
`multi-lang-core`	Go, TypeScript, Python, Rust, Kotlin	ubuntu-latest
`multi-lang-java`	Java	ubuntu-latest (continue-on-error)
`multi-lang-extended`	C, C++, JavaScript, PHP, Ruby, YAML, JSON, Dockerfile, C#, CSS, HTML	ubuntu-latest
`multi-lang-zig`	Zig	ubuntu-latest
`multi-lang-terraform`	Terraform	ubuntu-latest
`multi-lang-lua`	Lua	ubuntu-latest
`multi-lang-swift`	Swift	macos-latest
`multi-lang-scala`	Scala	ubuntu-latest (continue-on-error)
`multi-lang-gleam`	Gleam	ubuntu-latest
`multi-lang-elixir`	Elixir	ubuntu-latest (continue-on-error)
`multi-lang-prisma`	Prisma	ubuntu-latest (continue-on-error)
`multi-lang-sql`	SQL	ubuntu-latest (postgres:16 service)
`multi-lang-clojure`	Clojure	ubuntu-latest
`multi-lang-nix`	Nix	ubuntu-latest (continue-on-error)
`multi-lang-dart`	Dart	ubuntu-latest
`multi-lang-mongodb`	MongoDB	ubuntu-latest (continue-on-error)
`speculative-test`	Go, TypeScript, Python, Rust, C++, C#, Dart, Java (speculative sessions)	ubuntu-latest

Adding a language: what's required

Each new language needs three things:

langConfig entry in test/multi_lang_test.go buildLanguageConfigs():
- binary (language server executable name)
- serverArgs (e.g. []string{"--stdio"})
- fixture directory path
- file path (primary fixture file)
- hoverLine/hoverColumn: position of a named symbol in the primary file
- definitionLine/definitionColumn: position of a symbol whose definition is in secondFile
- referenceLine/referenceColumn: position to query for references
- completionLine/completionColumn: position inside a method call for completions
- workspaceSymbol: a symbol name that workspace symbol search should return
- secondFile: cross-file fixture (for definition + references across files)
- supportsFormatting: whether the server formats documents
- declarationLine/declarationColumn: optional, for C-style go_to_declaration
- highlightLine/highlightColumn: position for document highlight testing
- inlayHintEndLine: end line for inlay hint range
- renameSymbolLine/renameSymbolColumn/renameSymbolName: position and new name for rename testing (set to 0 to skip)
- codeActionLine/codeActionEndLine: line range for code action testing
Fixture files in test/fixtures/<lang>/:
- A primary file with a Person class/struct (or similar named symbol)
- A greeter cross-file that imports and calls Person
- A build/project file if the language server requires one (e.g. go.mod, build.zig, Package.swift, build.sbt)
- Follow the pattern of existing fixtures (hover target, definition cross-ref, completion context)
CI install step in the appropriate .github/workflows/ci.yml job:
- JVM-based: Java → multi-lang-java, Kotlin → multi-lang-core
- Lightweight npm/binary → multi-lang-extended
- macOS-only → dedicated job with runs-on: macos-latest
- Heavy/slow startup → dedicated job with continue-on-error: true
- Everything else → dedicated job (keeps extended job install time bounded)

Tier 3: next expansion candidates

Bash (bash-language-server)

Install: npm install -g bash-language-server
Binary: bash-language-server, language ID shellscript
Fixture: test/fixtures/bash/, simple script with functions
Notes: Good hover and completions. Definition/references limited.

Haskell (haskell-language-server)

Install: ghcup install hls (slow and fragile in CI)
Blocker: ghcup setup adds 5+ minutes; GHC version matrix complexity

Tier 4: complex / skip for now

Language	Server	Blocker
Haskell	haskell-language-server	ghcup setup is slow and fragile in CI
OCaml	ocamllsp	opam setup nontrivial
Elm	elm-language-server	Niche; requires elm + elm-format
R	r-languageserver	Niche; R package install in CI adds complexity

Language expansion summary

Tier	Languages	Count
Current	TypeScript, Python, Go, Rust, Java, C, PHP, C++, JavaScript, Ruby, YAML, JSON, Dockerfile, C#, Kotlin, Lua, Swift, Zig, CSS, HTML, Terraform, Scala, Gleam, Elixir, Prisma, SQL, Clojure, Nix, Dart, MongoDB	30
Tier 3 candidates	Bash	1
Potential total		31

The 30-language set covers systems, web, JVM, scripting, infrastructure, config, functional, schema, query, document-database, and Nix/functional-package-manager domains.