Herb Language Server

Package: @herb-tools/language-server

---

Language Server Protocol integration for HTML-aware ERB parsing using the Herb Parser.

Installation

Visual Studio Code

Install the Herb LSP extension from the Visual Studio Marketplace.

Cursor (Open VSX Registry)

Install the Herb LSP extension from the Open VSX Registry.

Zed

The Herb Language Server is part of the official Ruby extension for Zed. Just install the Ruby extension in Zed and you should be good to go.

Read more in the documentation.

Neovim (using nvim-lspconfig)

After installing the Herb Language Server (see below), add herb_ls to your Neovim config (requires nvim 0.11+):

require('lspconfig')
vim.lsp.enable('herb_ls')

Nova

After installing the Herb Language Server (see below), install the Herb LSP extension from the Nova Extension Library. The extension is a community plugin maintained at pat/herb-lsp.novaextension.

Sublime Text (using Sublime LSP)

After installing the Herb Language Server (see below) and Sublime LSP, update the preferences for the LSP package:

// LSP.sublime-settings
{
  "clients": {
    "herb": {
      "enabled": true,
      "command": [
        "herb-language-server",
        "--stdio"
      ],
      "selector": "text.html.ruby | text.html.rails",
      "settings": {
        "languageServerHerb.linter.enabled": true
      }
    }
  }
}

Manual Installation

You can use the language server in any editor that supports the Language Server Protocol.

NPM (Global)

npm install -g @herb-tools/language-server

Yarn 1 (Global)

yarn global add @herb-tools/language-server

Yarn 4

Yarn 4 removed global installs, use yarn dlx as the server command instead:

yarn dlx -q @herb-tools/language-server --stdio

Preview Releases

Want to try unreleased features? Use pkg.pr.new to run the language server from any commit or PR:

npx https://pkg.pr.new/@herb-tools/language-server@{commit} --stdio

Replace {commit} with a commit SHA (e.g., 0d2eabe) or branch name (e.g., main). Find available previews at pkg.pr.new/~/marcoroth/herb.

Run

herb-language-server --stdio

Usage

Usage: herb-language-server [options]

Options:

  --stdio          use stdio
  --node-ipc       use node-ipc
  --socket=<port>  use socket

NPX

Alternatively you can also run the language server directly with npx without installing anything:

npx @herb-tools/language-server --stdio

Configuration

The language server can be configured using a .herb.yml file in your project root. This configuration is shared across all Herb tools including the linter, formatter, and language server.

See the Configuration documentation for full details.

Example Configuration

.herb.yml

linter:
  enabled: true

formatter:
  enabled: true
  indentWidth: 2
  indentStyle: space
  maxLineLength: 80

Note: VS Code users can also control settings through languageServerHerb.* settings in VS Code preferences. Project configuration in .herb.yml takes precedence over editor settings.

Editor Settings

Some preferences are yours alone rather than the team's, so they live with your editor instead of in .herb.yml. The server reads them from the languageServerHerb section:

Setting	Default	Description
linter.enabled	true	Enable/disable the linter
linter.fixOnSave	true	Automatically apply autocorrectable fixes on save
formatter.enabled	false	Enable/disable the formatter (experimental)
formatter.indentWidth	2	Number of spaces per indentation level
formatter.indentStyle	space	Character used for indentation (space or tab)
formatter.maxLineLength	80	Maximum line length before wrapping
inlayHints.enabled	true	Annotate closing tags with what they close
inlayHints.minimumLines	10	How far below its opening tag a closing tag must be to get a hint
inlayHints.maximumClasses	2	How many of an element's classes to include in its hint

How you set them depends on the editor. VS Code and Cursor contribute them as languageServerHerb.* preferences, so you set them in your settings.json or through the settings UI:

settings.json

{
  "languageServerHerb.inlayHints.minimumLines": 4
}

Editors that keep language server settings under their own key, like Zed, pass them at startup as initialization options instead, nested rather than dotted and without the languageServerHerb prefix:

settings.json

{
  "lsp": {
    "herb": {
      "initialization_options": {
        "inlayHints": {
          "minimumLines": 4
        }
      }
    }
  }
}

Anything you leave out falls back to the default, and .herb.yml still wins for the settings a project can own, which is whether the linter and formatter run at all.