Language servers

Rexa runs language servers for diagnostics, hover information and code navigation. Each server is off until you turn it on, except JSON, which is on by default.

Turn a server on

The first time you open a file whose language has a server, Rexa offers Enable. You can also turn servers on in Settings → Language servers, or in settings.json:

settings.json

{
  "lsp": { "enabled_servers": ["rust-analyzer", "typescript-language-server"] }
}

Enabling a server applies to every project.

Built-in servers

Name	Languages	Command
`rust-analyzer`	Rust	`rust-analyzer`
`typescript-language-server`	TypeScript, JavaScript	`typescript-language-server --stdio`
`pyright`	Python	`pyright-langserver --stdio`
`gopls`	Go	`gopls`
`clangd`	C, C++	`clangd`
`zls`	Zig	`zls`
`lua-language-server`	Lua	`lua-language-server`
`vscode-json-language-server`	JSON, JSONC	`vscode-json-language-server --stdio`

Rexa looks for each command on your PATH, including the PATH your login shell sets. The JSON and TypeScript servers need no install: when the command is missing, Rexa runs a pinned copy and caches it in ~/Library/Caches/deno.

Features

Feature	How
Diagnostics	Underlines and gutter dots. Counts in the status bar.
Hover	Rest the pointer for 300 ms, or `K` in Vim normal mode.
Go to definition	`F12` or `⌘`-click
Go to declaration	`⌃` `F12`
Go to type definition	`⌘` `F12` or `⌘` `⇧`-click
Go to implementation	`⇧` `F12`

The jumps also work from git diffs and the right-click menu.

Problems

Action	Shortcut
Problems tab	`⌘` `⇧` `M`
Problems palette	`⌃` `⇧` `M`
Next / previous problem	`F8` / `⇧` `F8`

The Problems tab lists errors and warnings for the worktree, grouped by file, with filters for each. Click the counts in the status bar for the same list as a popup.

Server status

Each running server has a status bar item with its name and progress, such as Rust: Indexing (42%). A trailing … means starting, yellow means not installed, and red means it failed.

Click the item for its details and a menu: Restart, Stop or Start, Show Logs, the server’s own commands (such as Reload Workspace for Rust), the toolchain picker, and Restart All Language Servers.

Toolchains

Rexa picks a toolchain per server root: the TypeScript version, Python interpreter, Node version, Rust toolchain or Go toolchain. It prefers the one closest to the project, never a machine-wide install.

TypeScript uses the project’s node_modules/typescript. Without one, Rexa uses a bundled TypeScript 7, or TypeScript 5.9 for projects that declare TypeScript 6 or older.
Python uses the project’s .venv.
Node follows .nvmrc, .node-version or volta.node. Write a version number; aliases such as lts/* are not resolved.

Change it from the server’s status item (TypeScript Version…, Python Interpreter…), or pin it per project in .rexa/config.json. New terminals and agents in the worktree get the same Python and Node first on PATH.

Add or replace a server

lsp.servers adds a server, or replaces a built-in one with the same name:

settings.json

{
  "lsp": {
    "enabled_servers": ["ruby-lsp"],
    "servers": {
      "ruby-lsp": {
        "label": "Ruby",
        "languages": ["ruby"],
        "command": "ruby-lsp",
        "args": [],
        "root_markers": ["Gemfile"]
      }
    }
  }
}

Each server also accepts env, initialization_options and settings. Zed extensions can provide servers too; see Themes and extensions.

From the command line

rexa lsp reports and controls servers in the running app:

Terminal

rexa lsp                          # status of every server
rexa lsp diagnostics src/main.rs  # diagnostics for a file
rexa lsp restart rust-analyzer    # restart one server
rexa lsp toolchain python .venv   # pick a toolchain

Each server’s log is in ~/Library/Logs/rexa/lsp/.