---
title: Editor Support
description: Configure an editor to use xx's built-in Starlark language server.
---

# Editor Support

`xx lsp` runs a Language Server Protocol server over standard input and standard output. Configure an editor's LSP client to start `xx lsp` for xx Starlark files.

The server handles `.star`, `.build`, `.starlark`, `.bzl`, and `.bazel` files inside a `.xx` directory. Files elsewhere are ignored.

Supported features include:

- Completion for built-in package names, package symbols, loaded symbols, local variables, function parameters, and standard Starlark names.
- Hover documentation and signatures from xx's built-in package catalog.
- Go to definition for names defined in the same file, including loaded symbol aliases.
- Syntax, name-resolution, package-version, package-symbol, and built-in function-call type diagnostics.

The server uses full-document synchronization and UTF-16 positions. It does not execute build files or download tools while analyzing them.

## Neovim

Neovim 0.11 and newer can configure the server through `vim.lsp.config`. This setup uses Neovim's existing `starlark` and `bzl` filetypes so syntax highlighting continues to work. It also recognizes `.build` files below `.xx` as Starlark and prevents the server from attaching to files outside `.xx`.

```lua
local function xx_root_dir(bufnr, on_dir)
    local filename = vim.api.nvim_buf_get_name(bufnr)
    for directory in vim.fs.parents(filename) do
        if vim.fs.basename(directory) == ".xx" then
            on_dir(vim.fs.dirname(directory))
            return
        end
    end
end

-- Set .build files as Starlark
vim.filetype.add({
    pattern = {
        [".*/%.xx/.*%.build"] = { "starlark", { priority = 1000 } },
    },
})

vim.lsp.config("xx", {
    cmd = { "xx", "lsp" },
    filetypes = { "starlark", "bzl" },
    root_dir = xx_root_dir,
})

vim.lsp.enable("xx")
```

The `xx` executable must be available on Neovim's `PATH`.

## OpenCode

Add xx as a custom language server in the project's `opencode.json`:

```json
{
  "$schema": "https://opencode.ai/config.json",
  "lsp": {
    "xx": {
      "command": ["xx", "lsp"],
      "extensions": [".star", ".build", ".starlark", ".bzl", ".bazel"]
    }
  }
}
```

The `xx` executable must be available on OpenCode's `PATH`. Restart OpenCode after changing its configuration.

## Visual Studio Code

Build the extension yourself using `xx run vscode` or install it from [Open VSX Registry](https://open-vsx.org/extension/tsukinoko-kun/withxx) or [Visual Studio Marketplace](https://marketplace.visualstudio.com/items?itemName=tsukinoko-kun.withxx).

## Other Editors

The exact configuration depends on the editor. Register a Starlark language server with this command:

```sh
xx lsp
```

Associate it with the supported file extensions, then use a `.xx` directory as part of the file path. No project initialization request or command-line arguments are required.

<!--
Sitemap

URL: https://withxx.dev/index.md
Title: xx
Description: Practical, reproducible builds without build-system ceremony

URL: https://withxx.dev/examples/commands.md
Title: Command Examples
Description: General command, environment, and entrypoint patterns.

URL: https://withxx.dev/examples/go.md
Title: Go Examples
Description: Common Go build patterns with managed SDKs.

URL: https://withxx.dev/examples/nodejs.md
Title: Node.js Examples
Description: Common Node.js task patterns with a managed distribution.

URL: https://withxx.dev/examples/zig.md
Title: Zig Examples
Description: Direct Zig commands and Go CGO builds with a managed Zig distribution.

URL: https://withxx.dev/load.md
Title: Loading Files
Description: Split xx configuration into local Starlark modules.

URL: https://withxx.dev/lsp.md
Title: Editor Support
Description: Configure an editor to use xx's built-in Starlark language server.

URL: https://withxx.dev/packages/cloudflare/cf_d1_create.md
Title: cf_d1_create
Description: Provision a Cloudflare D1 database with Wrangler.

URL: https://withxx.dev/packages/cloudflare/cf_kv_create.md
Title: cf_kv_create
Description: Provision a Cloudflare Workers KV namespace with Wrangler.

URL: https://withxx.dev/packages/cloudflare/cf_queue_create.md
Title: cf_queue_create
Description: Provision and configure a Cloudflare Queue with Wrangler.

URL: https://withxx.dev/packages/cloudflare/cf_r2_create.md
Title: cf_r2_create
Description: Provision and configure a Cloudflare R2 bucket with Wrangler.

URL: https://withxx.dev/packages/cloudflare/cf_worker_config.md
Title: cf_worker_config
Description: Define an in-memory Cloudflare Worker configuration.

URL: https://withxx.dev/packages/cloudflare/cf_wrangler_deploy.md
Title: cf_wrangler_deploy
Description: Deploy a Cloudflare Worker with a temporary Wrangler configuration.

URL: https://withxx.dev/packages/cloudflare/cf_wrangler_dev.md
Title: cf_wrangler_dev
Description: Run one or more Cloudflare Workers with Wrangler dev.

URL: https://withxx.dev/packages/cmake/cmake.md
Title: cmake
Description: Activate managed CMake for dependent tasks.

URL: https://withxx.dev/packages/cmake/cmake_build.md
Title: cmake_build
Description: Build a generated project with managed CMake.

URL: https://withxx.dev/packages/cmake/cmake_generate.md
Title: cmake_generate
Description: Generate a project build system with managed CMake.

URL: https://withxx.dev/packages/doppler/doppler_secrets.md
Title: doppler_secrets
Description: Load Doppler secrets into dependent task environments.

URL: https://withxx.dev/packages/git/git_clone.md
Title: git_clone
Description: Materialize a pinned Git source tree with host Git configuration and access.

URL: https://withxx.dev/packages/git/git_commit.md
Title: git_commit
Description: Stage and commit changes in a Git repository.

URL: https://withxx.dev/packages/git/git_init_repository.md
Title: git_init_repository
Description: Ensure an empty SHA-1 or SHA-256 Git repository exists.

URL: https://withxx.dev/packages/git/git_push.md
Title: git_push
Description: Push commits from a Git repository.

URL: https://withxx.dev/packages/git/git_semver_latest.md
Title: git_semver_latest
Description: Read the latest semantic version from local Git tags.

URL: https://withxx.dev/packages/git/git_semver_next.md
Title: git_semver_next
Description: Calculate the next semantic version from local Conventional Commits.

URL: https://withxx.dev/packages/git/git_sha.md
Title: git_sha
Description: Resolve a local Git revision to its commit ID.

URL: https://withxx.dev/packages/git/git_tag.md
Title: git_tag
Description: Create a lightweight or annotated Git tag.

URL: https://withxx.dev/packages/go/go.md
Title: go
Description: Activate a managed Go SDK for dependent tasks.

URL: https://withxx.dev/packages/go/go_binary.md
Title: go_binary
Description: Build a Go command with a managed SDK.

URL: https://withxx.dev/packages/go/go_install.md
Title: go_install
Description: Install a versioned Go command for dependent tasks.

URL: https://withxx.dev/packages/go/go_protobuf.md
Title: go_protobuf
Description: Install protoc-gen-go and provide it as a Protobuf generator.

URL: https://withxx.dev/packages/go/go_run.md
Title: go_run
Description: Run a local program or versioned Go command with a managed SDK.

URL: https://withxx.dev/packages/go/go_test.md
Title: go_test
Description: Test Go packages with a managed SDK.

URL: https://withxx.dev/packages/http/http_proxy.md
Title: http_proxy
Description: Route local HTTP and WebSocket traffic between development servers.

URL: https://withxx.dev/packages/io/io_append_text.md
Title: io_append_text
Description: Append text to a file asynchronously.

URL: https://withxx.dev/packages/io/io_copy.md
Title: io_copy
Description: Copy a file or directory asynchronously.

URL: https://withxx.dev/packages/io/io_glob.md
Title: io_glob
Description: Find project files and directories with recursive glob patterns.

URL: https://withxx.dev/packages/io/io_read_text.md
Title: io_read_text
Description: Read a text file during build evaluation.

URL: https://withxx.dev/packages/io/io_rm.md
Title: io_rm
Description: Remove a file asynchronously.

URL: https://withxx.dev/packages/io/io_rmdir.md
Title: io_rmdir
Description: Remove a directory tree asynchronously.

URL: https://withxx.dev/packages/io/io_stat.md
Title: io_stat
Description: Read file information during build evaluation.

URL: https://withxx.dev/packages/io/io_write_text.md
Title: io_write_text
Description: Write text to a file asynchronously.

URL: https://withxx.dev/packages/ninja/ninja.md
Title: ninja
Description: Activate managed Ninja for dependent tasks.

URL: https://withxx.dev/packages/nodejs/nodejs.md
Title: nodejs
Description: Activate managed Node.js for dependent tasks.

URL: https://withxx.dev/packages/nodejs/npm_install.md
Title: npm_install
Description: Install dependencies with the package.json-selected manager.

URL: https://withxx.dev/packages/nodejs/npm_run.md
Title: npm_run
Description: Run a project package script with the package.json-selected manager.

URL: https://withxx.dev/packages/nodejs/npx_run.md
Title: npx_run
Description: Run a versioned npm package command with managed npx.

URL: https://withxx.dev/packages/os/env_append.md
Title: env_append
Description: Append an item to a list-like environment variable.

URL: https://withxx.dev/packages/os/env_get.md
Title: env_get
Description: Read a value from a task environment while evaluating Starlark.

URL: https://withxx.dev/packages/os/env_prepend.md
Title: env_prepend
Description: Prepend an item to a list-like environment variable.

URL: https://withxx.dev/packages/os/env_set.md
Title: env_set
Description: Set an environment variable for dependent tasks.

URL: https://withxx.dev/packages/os/env_unset.md
Title: env_unset
Description: Remove an environment variable from dependent tasks.

URL: https://withxx.dev/packages/os/os_arch.md
Title: os_arch
Description: Identify the host processor architecture.

URL: https://withxx.dev/packages/os/os_kernel.md
Title: os_kernel
Description: Identify the host operating system kernel.

URL: https://withxx.dev/packages/os/os_msvc.md
Title: os_msvc
Description: Activate the host Microsoft Visual C++ tools.

URL: https://withxx.dev/packages/os/os_run.md
Title: os_run
Description: Run a command from a project directory.

URL: https://withxx.dev/packages/os/os_system_tools.md
Title: os_system_tools
Description: Activate standard host operating-system utilities.

URL: https://withxx.dev/packages/os/os_xcode.md
Title: os_xcode
Description: Activate the host Xcode tools.

URL: https://withxx.dev/packages/os/path_make_absolute.md
Title: path_make_absolute
Description: Resolve a relative path from the project root.

URL: https://withxx.dev/packages/protobuf/protobuf_generate.md
Title: protobuf_generate
Description: Generate source code with a managed Protobuf compiler.

URL: https://withxx.dev/packages/protobuf/protobuf_generator.md
Title: protobuf_generator
Description: Adapt an installed protoc plugin dependency for code generation.

URL: https://withxx.dev/packages/protobuf/protoc.md
Title: protoc
Description: Activate a managed Protobuf compiler for dependent tasks.

URL: https://withxx.dev/packages/secrets/xx_secrets.md
Title: xx_secrets
Description: Load xx project secrets into dependent task environments.

URL: https://withxx.dev/packages/stripe/stripe.md
Title: stripe
Description: Activate a managed Stripe CLI for dependent tasks.

URL: https://withxx.dev/packages/stripe/stripe_listen.md
Title: stripe_listen
Description: Forward Stripe webhook events to a local endpoint.

URL: https://withxx.dev/packages/text/text_template.md
Title: text_template
Description: Render Go text templates from Starlark data and functions.

URL: https://withxx.dev/packages/xxrpc/xxrpc_client.md
Title: xxrpc_client
Description: Generate typed HTTP and WebSocket RPC clients for ECMAScript or Go.

URL: https://withxx.dev/packages/xxrpc/xxrpc_handler.md
Title: xxrpc_handler
Description: Generate typed framework-neutral ECMAScript RPC handler classes.

URL: https://withxx.dev/packages/zig/zig.md
Title: zig
Description: Activate managed Zig for dependent tasks.

URL: https://withxx.dev/packages/zig/zig_cc.md
Title: zig_cc
Description: Configure managed Zig as a C and C++ compiler.

URL: https://withxx.dev/packages.md
Title: Built-in Packages
Description: Versioned toolchains, commands, and task environment helpers provided by xx.

URL: https://withxx.dev/secrets.md
Title: Secret manager
Description: Store project secrets locally and provide them to xx tasks.

URL: https://withxx.dev/xxrpc.md
Title: xxRPC
Description: Design portable xxRPC contracts that keep application semantics in Protobuf.
-->