name: lsp-setup description: 'Enable code intelligence (go-to-definition, find-references, hover, type info) for any programming language by installing and configuring an LSP server for Copilot CLI. Detects the OS, installs the right server, and generates the JSON configuration (user-level or repo-level). Use when you need deeper code understanding and no LSP server is configured, or when the user asks to set up, install, or configure an LSP server.'

LSP Setup for GitHub Copilot CLI

UTILITY SKILL — installs and configures Language Server Protocol servers for Copilot CLI. USE FOR: "setup LSP", "install language server", "configure LSP for Java", "add TypeScript LSP", "enable code intelligence", "I need go-to-definition", "find references not working", "need better code understanding" DO NOT USE FOR: general coding tasks, IDE/editor LSP configuration, non-Copilot-CLI setups

Workflow

1. Ask the language — use ask_user to ask which programming language(s) the user wants LSP support for
2. Detect the OS — run uname -s (or check for Windows via $env:OS / %OS%) to determine macOS, Linux, or Windows
3. Look up the LSP server — read references/lsp-servers.md for known servers, install commands, and config snippets
4. Ask scope — use ask_user to ask whether the config should be user-level (~/.copilot/lsp-config.json) or repo-level (lsp.json at the repo root or .github/lsp.json)
5. Install the server — run the appropriate install command for the detected OS
6. Write the config — merge the new server entry into the chosen config file (~/.copilot/lsp-config.json for user-level; lsp.json or .github/lsp.json for repo-level). If a repo-level config already exists, keep using that location; otherwise ask the user which repo-level location they prefer. Create the file if missing and preserve existing entries.
7. Verify — confirm the LSP binary is on $PATH and the config file is valid JSON

Configuration Format

Copilot CLI reads LSP configuration from user-level or repo-level locations, and repo-level config takes precedence over user-level config:

• User-level: ~/.copilot/lsp-config.json
• Repo-level: lsp.json (repo root) or .github/lsp.json

The JSON structure:

{
  "lspServers": {
    "<server-key>": {
      "command": "<binary>",
      "args": ["--stdio"],
      "fileExtensions": {
        ".<ext>": "<languageId>",
        ".<ext2>": "<languageId>"
      }
    }
  }
}

Key rules

• command is the binary name (must be on $PATH) or an absolute path.
• args almost always includes "--stdio" to use standard I/O transport.
• fileExtensions maps each file extension (with leading dot) to a Language ID.
• Multiple servers can coexist in lspServers.
• When merging into an existing file, never overwrite other server entries — only add or update the target language key.

Behavior

• Always use ask_user with choices when asking the user to pick a language or scope.
• If the language is not listed in references/lsp-servers.md, search the web for "<language> LSP server" and guide the user through manual configuration.
• If a package manager is not available (e.g. no Homebrew on macOS), suggest alternative install methods from the reference file.
• After installation, run which <binary> (or where.exe on Windows) to confirm the binary is accessible.
• Show the user the final config JSON before writing it.
• If the config file already exists, read it first and merge — do not clobber.

Verification

After setup, tell the user:

1. Type /exit to quit Copilot CLI — this is required so the new LSP configuration is loaded on next launch
2. Re-launch copilot in a project with files of the configured language
3. Run /lsp to check the server status
4. Try code intelligence features like go-to-definition or hover