Lsp Setup

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

Known LSP Servers for Copilot CLI

Reference data for the lsp-setup skill. Each section contains install commands per OS and a ready-to-use config snippet.

Config snippet format: Each snippet below shows the object to insert as a value under the top-level lspServers key. A complete config file looks like: { "lspServers": { <snippet here> } }. When adding multiple languages, merge their snippets as sibling keys under lspServers.

---

TypeScript / JavaScript

Server: typescript-language-server

Install

Config snippet

{
  "typescript": {
    "command": "typescript-language-server",
    "args": ["--stdio"],
    "fileExtensions": {
      ".ts": "typescript",
      ".tsx": "typescriptreact",
      ".js": "javascript",
      ".jsx": "javascriptreact"
    }
  }
}

---

Java

Server: Eclipse JDT Language Server (jdtls)

Requires Java 21+ on JAVA_HOME or $PATH.

Install

On macOS with Homebrew, the binary is installed as jdtls on $PATH.

Config snippet

{
  "java": {
    "command": "jdtls",
    "args": [],
    "fileExtensions": {
      ".java": "java"
    }
  }
}

Note: The jdtls wrapper script handles --stdio mode internally. If using a manual install, you may need to invoke the launcher jar directly — see the jdtls README for details.

---

Python

Server: pyright

Install

Config snippet

{
  "python": {
    "command": "pyright-langserver",
    "args": ["--stdio"],
    "fileExtensions": {
      ".py": "python"
    }
  }
}

---

Go

Server: gopls

Install

Config snippet

{
  "go": {
    "command": "gopls",
    "args": ["serve"],
    "fileExtensions": {
      ".go": "go"
    }
  }
}

---

Rust

Server: rust-analyzer

Install

Config snippet

{
  "rust": {
    "command": "rust-analyzer",
    "args": [],
    "fileExtensions": {
      ".rs": "rust"
    }
  }
}

---

C / C++

Server: clangd

Install

Config snippet

{
  "cpp": {
    "command": "clangd",
    "args": ["--background-index"],
    "fileExtensions": {
      ".c": "c",
      ".h": "c",
      ".cpp": "cpp",
      ".cxx": "cpp",
      ".cc": "cpp",
      ".hpp": "cpp",
      ".hxx": "cpp"
    }
  }
}

---

C# (.NET)

Server: Roslyn Language Server (via dotnet dnx)

Install

Config snippet

{
  "csharp": {
    "command": "dotnet",
    "args": ["dnx", "roslyn-language-server", "--yes", "--prerelease", "--", "--stdio", "--autoLoadProjects"],
    "fileExtensions": {
      ".cs": "csharp"
    }
  }
}

---

Ruby

Server: solargraph

Install

Config snippet

{
  "ruby": {
    "command": "solargraph",
    "args": ["stdio"],
    "fileExtensions": {
      ".rb": "ruby",
      ".rake": "ruby",
      ".gemspec": "ruby"
    }
  }
}

---

PHP

Server: intelephense

Install

Config snippet

{
  "php": {
    "command": "intelephense",
    "args": ["--stdio"],
    "fileExtensions": {
      ".php": "php"
    }
  }
}

---

Kotlin

Server: kotlin-language-server

Install

Config snippet

{
  "kotlin": {
    "command": "kotlin-language-server",
    "args": [],
    "fileExtensions": {
      ".kt": "kotlin",
      ".kts": "kotlin"
    }
  }
}

---

Swift

Server: sourcekit-lsp (bundled with Swift toolchain)

Install

Config snippet

{
  "swift": {
    "command": "sourcekit-lsp",
    "args": [],
    "fileExtensions": {
      ".swift": "swift"
    }
  }
}

On macOS you may need to use the full path: /usr/bin/sourcekit-lsp or set command to xcrun with args: ["sourcekit-lsp"].

---

Lua

Server: lua-language-server

Install

Config snippet

{
  "lua": {
    "command": "lua-language-server",
    "args": [],
    "fileExtensions": {
      ".lua": "lua"
    }
  }
}

---

YAML

Server: yaml-language-server

Install

Config snippet

{
  "yaml": {
    "command": "yaml-language-server",
    "args": ["--stdio"],
    "fileExtensions": {
      ".yaml": "yaml",
      ".yml": "yaml"
    }
  }
}

---

Bash / Shell

Server: bash-language-server

Install

Config snippet

{
  "bash": {
    "command": "bash-language-server",
    "args": ["start"],
    "fileExtensions": {
      ".sh": "shellscript",
      ".bash": "shellscript",
      ".zsh": "shellscript"
    }
  }
}