mui-lsp

LSP (Language Server Protocol) plugin for Mui editor.

Features

• Hover: Show documentation for symbol under cursor (K or <Space>hf or :LspHover)
• Go to Definition: Jump to symbol definition (<Space>df or :LspDefinition)
• Go to Type Definition: Jump to type definition or toggle between Ruby/RBS files (<Space>tf or :LspTypeDefinition)
• Find References: Show all references to symbol (<Space>rf or :LspReferences)
• Completion: Get code completion suggestions (<Space>cf or :LspCompletion)
• Format: Format current file with LSP server (<Space>ff or :LspFormat)
• Diagnostics: Display errors and warnings from LSP server (:LspDiagnostics)

Supported Language Servers

Pre-configured servers for Ruby:

• Solargraph - Full-featured Ruby language server
• ruby-lsp - Shopify's Ruby language server
• Kanayago - Realtime Ruby Syntax Check server
• RuboCop (LSP mode) - Ruby linter with LSP support
• TypeProf - Ruby type analysis and inference
• Steep - Ruby type checker with RBS support

Custom servers can be configured for other languages.

Installation

Add to your .muirc:

# ~/.muirc
Mui.use "mui-lsp"

Or if installing from a local path:

# ~/.muirc
Mui.use "mui-lsp", path: "/path/to/mui-lsp"

Configuration (Required)

Important: mui-lsp does not auto-detect LSP servers. You must explicitly configure which server(s) to use in your .muirc.

Quick Setup

Use the Mui.lsp DSL block to configure servers:

# ~/.muirc
Mui.use "mui-lsp"

Mui.lsp do
  use :solargraph
end

Available pre-configured servers:

• :solargraph - Solargraph (full-featured Ruby LSP)
• :ruby_lsp - ruby-lsp (Shopify's Ruby LSP)
• :rubocop - RuboCop in LSP mode
• :kanayago - Kanayago (Japanese Ruby LSP)
• :typeprof - TypeProf (Ruby type analysis)
• :steep - Steep (Ruby type checker with RBS)

TypeProf Setup

TypeProf requires a configuration file in your project root. Run:

typeprof --init

This creates typeprof.conf.jsonc with default settings:

{
  "typeprof_version": "experimental",
  "rbs_dir": "sig/",
  "analysis_unit_dirs": ["lib"]
}

TypeProf will only analyze files in the directories specified in analysis_unit_dirs. Without this configuration file, TypeProf will not track documents and type definition features will not work.

Steep Setup

Steep requires a Steepfile in your project root. Create one with:

# Steepfile
target :lib do
  signature "sig"
  check "lib"
end

Place your RBS type definitions in the sig/ directory.

Custom Server Configuration

For other languages or custom setups, use the server method:

# ~/.muirc
Mui.use "mui-lsp"

Mui.lsp do
  # TypeScript/JavaScript
  server name: "typescript",
         command: "typescript-language-server --stdio",
         language_ids: ["typescript", "javascript"],
         file_patterns: ["**/*.ts", "**/*.tsx", "**/*.js", "**/*.jsx"]

  # Python (pyright)
  server name: "pyright",
         command: "pyright-langserver --stdio",
         language_ids: ["python"],
         file_patterns: ["**/*.py"]
end

Multiple Servers

You can enable multiple servers for different file types:

# ~/.muirc
Mui.use "mui-lsp"

Mui.lsp do
  # Ruby
  use :solargraph

  # TypeScript/JavaScript
  server name: "typescript",
         command: "typescript-language-server --stdio",
         language_ids: ["typescript", "javascript"],
         file_patterns: ["**/*.ts", "**/*.tsx", "**/*.js", "**/*.jsx"]
end

Usage

Starting LSP Server

LSP servers are automatically started when you open a file that matches their configured file patterns.

To manually start a server:

:LspStart solargraph
:LspStart ruby-lsp
:LspStart rubocop

Commands

Command	Description
:LspStart <name>	Start a specific LSP server
:LspStop [name]	Stop a server (all if no name given)
:LspStatus	Show running and registered servers
:LspHover	Show hover information
:LspDefinition	Go to definition
:LspTypeDefinition	Go to type definition
:LspReferences	Find all references
:LspCompletion	Show completion menu
:LspDiagnostics	Show diagnostics for current file
:LspDiagnosticShow	Show diagnostic at cursor in floating window
:LspFormat	Format current file
:LspLog	Show LSP server logs in a buffer
:LspDebug	Show debug information
:LspOpen	Manually notify LSP server about current file

Keymaps

Key	Mode	Description
K	Normal	Show hover information (in floating window)
<Space>df	Normal	Go to definition
<Space>tf	Normal	Go to type definition (Ruby: toggle .rb/.rbs)
<Space>rf	Normal	Find references
<Space>hf	Normal	Show hover information (alternative to K)
<Space>cf	Normal	Show completion
<Space>ef	Normal	Show diagnostic at cursor (in floating window)
<Space>ff	Normal	Format current file
Esc	Normal	Close floating window / picker

Location Picker (for Definition/References with multiple candidates)

When multiple definitions or references are found, a picker buffer opens. Use standard Vim navigation:

Key	Description
j/k	Navigate up/down (native cursor movement)
\ + Enter	Open selected location in current window
Ctrl+t	Open selected location in new tab
\q / \ + Esc	Close picker

Architecture

mui-lsp/
  lib/mui/lsp/
    protocol/          # LSP protocol definitions
      position.rb      # Position (line, character)
      range.rb         # Range (start, end positions)
      location.rb      # Location (URI, range)
      diagnostic.rb    # Diagnostic (error/warning/info)
    handlers/          # Response handlers
      base.rb          # Base handler class
      hover.rb         # Hover response handler
      definition.rb    # Definition response handler
      type_definition.rb # Type definition response handler
      references.rb    # References response handler
      diagnostics.rb   # Diagnostics notification handler
      completion.rb    # Completion response handler
      formatting.rb    # Formatting response handler
    json_rpc_io.rb     # JSON-RPC 2.0 over stdio
    request_manager.rb # Request ID and callback management
    server_config.rb   # Server configuration presets
    client.rb          # LSP client (manages server process)
    text_document_sync.rb # Document synchronization
    manager.rb         # Multi-server manager
    plugin.rb          # Mui plugin integration

Development

cd mui-lsp
bundle install
bundle exec rake test
bundle exec rubocop

License

MIT License