LSP Setup

Configure the right Language Server for a project so the lsp MCP tools (diagnostics, goto_definition, find_references, symbols, rename) actually work. This skill is an index: detect what a project needs, install the server, write the config, then verify with a real roundtrip.

The list of servers we ship as builtin is the source of truth in packages/lsp-tools-mcp/src/lsp/server-definitions.ts (BUILTIN_SERVERS + LSP_INSTALL_HINTS). The per-language references below mirror it.

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PHASE 0 — LANGUAGE GATE (run first)

Identify the language from the file extension, then read the matching reference before installing or configuring anything.

Extension(s)	Reference
.ts .tsx .js .jsx .mjs .cjs .mts .cts .vue .svelte .astro	references/typescript/README.md
.py .pyi	references/python/README.md
.go	references/go/README.md
.rs	references/rust/README.md
.c .cpp .cc .cxx .h .hpp .hh .hxx	references/c-cpp/README.md
.java	references/java/README.md
.kt .kts	references/kotlin/README.md
.cs .razor .cshtml	references/csharp/README.md
.swift	references/swift/README.md
.rb .rake .gemspec .ru	references/ruby/README.md
.php	references/php/README.md
.dart	references/dart/README.md
.ex .exs	references/elixir/README.md
.zig .zon	references/zig/README.md
.lua	references/lua/README.md
.sh .bash .zsh .ksh	references/bash/README.md
.yaml .yml	references/yaml/README.md
.tf .tfvars	references/terraform/README.md
.hs .lhs	references/haskell/README.md
.jl	references/julia/README.md

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WORKFLOW — detect → install → configure → verify

1. Detect

Scan the project to see which languages are present and whether each server is installed and configured:

bun scripts/detect-lsp.ts <projectDir>      # human report (default: cwd)
bun scripts/detect-lsp.ts <projectDir> --json

For each detected language it prints the builtin server id, the executable it needs on PATH, whether that executable is installed, an install hint, and whether a project config file already references it.

2. Install

Open references/<language>/README.md and run the install command for your OS. Then confirm the executable resolves:

command -v <server-executable>   # e.g. typescript-language-server, gopls, rust-analyzer

3. Configure

Most builtin servers need no config — they are resolved automatically by file extension. Write config only to: pick between competing servers, set a priority, pass initialization options, override extensions, set env, or disable a server.

Two project-scoped config files, identical JSON shape:

• Codex harness → .codex/lsp-client.json (user: ~/.codex/lsp-client.json)
• OpenCode/omo harness → .opencode/lsp.json (also .omo/lsp.json)

{
  "lsp": {
    "<server-id>": {
      "command": ["<bin>", "<args>"],   // optional for builtin ids (supplied automatically)
      "extensions": [".ext"],            // optional override
      "priority": 100,                    // higher wins when several servers match an extension
      "initialization": { },              // server-specific initializationOptions
      "env": { "KEY": "value" },          // optional
      "disabled": false                   // set true to turn a server off
    }
  }
}

Rules enforced by config-loader.ts:

• In a project config (.codex/lsp-client.json, .opencode/lsp.json) an entry whose id is a builtin server inherits command automatically — you only override extensions / priority / initialization. A non-builtin id in a project config is ignored.
• To define a fully custom (non-builtin) server with its own command, put it in the user config (~/.codex/lsp-client.json, or the path set by LSP_TOOLS_MCP_USER_CONFIG), where command + extensions are honored.
• Project entries win over user entries; both win over builtin defaults.

Each language reference gives a ready-to-paste snippet.

4. Verify

Run a real diagnostics roundtrip against a source file. This spawns the server, opens the file, requests diagnostics, and reports OK/FAIL:

bun scripts/verify-lsp.ts <path/to/file.ext>
bun scripts/verify-lsp.ts <file> --timeout=90000

OK = the server started and answered. FAIL: language server not installed = go back to step 2. Other FAIL text carries the server/startup error. SKIP = the engine source could not be located; run from inside the omo repo/worktree, or call the lsp MCP diagnostics tool directly.

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Scripts

Script	Purpose
scripts/detect-lsp.ts	Scan a directory; per detected language report server id, install status, install hint, config status. --json for machine output.
scripts/verify-lsp.ts	Real LSP diagnostics roundtrip for one file via the lsp-tools-mcp engine; OK/FAIL/SKIP + exit code 0/1/3.
scripts/lsp-server-table.ts	Embedded snapshot of the primary builtin server per language (mirrors server-definitions.ts).

Run with Bun: curl -fsSL https://bun.sh/install | bash.