Clangd LSP

Use clangd for C and C++ code navigation and diagnostics in Codex. Supported source extensions are .c, .h, .cpp, .cc, .cxx, .hpp, .hxx, .C, .H.

Prerequisites

• Node.js 22 or newer on the Codex host's PATH.
• Use the project's compilation database for accurate build flags. Language-server documentation

Automatic clangd installation

If clangd is not available on PATH, the plugin downloads the latest stable x64 release from the official clangd releases and verifies it against GitHub's published SHA-256 digest. It extracts the binary and builtin headers into the user's cache without changing the system PATH or requiring administrator privileges.

• Windows: %LOCALAPPDATA%\codex-plugin-ports\clangd-lsp
• macOS: ~/Library/Caches/codex-plugin-ports/clangd-lsp
• Linux: XDG_CACHE_HOME, or ~/.cache if it is unset, followed by /codex-plugin-ports/clangd-lsp

Automatic installation runs only when the configured clangd command is missing. It requires an internet connection on first use. Other operating systems and processor architectures still need a manual clangd installation.

Use in Codex

After adding the marketplace, install this plugin and start a new Codex conversation.

codex plugin add 'clangd-lsp@codex-plugin-ports'

Ask Codex to use the clangd language-server tools for your project. Call lsp_start with the absolute project root and poll lsp_status if initialization is pending. Queries use saved files and zero-based UTF-16 positions. The available features and indexing behavior depend on the native server.

Open trusted workspaces. A native language server can run build or project tools while indexing. Stop the workspace with lsp_stop when you finish or before starting another workspace.

Upstream and changes

Adapted from Anthropic's clangd-lsp under the Apache License 2.0. This port keeps the upstream file mappings and uses a local MCP bridge to start the language server and query it from Codex.