Language Server

Draft provides a Language Server for IDE integration with full editing features.

Installation

draft lsp install

Features

Code Completion

Intelligent completion for:

• Variables and actions
• Record fields
• Module imports
• Type members
• Keywords

@// Type @user# to see available fields
@user = User { name: "Alice", age: 30 }
@user#name  @// Completion shows: name, age, email

Hover Information

Hover over any symbol to see:

• Type information
• Documentation
• Signature

action add(@a: Int, @b: Int) -> Int
    return @a + @b
fin action.

@// Hover over "add" shows:
@// action add(a: Int, b: Int) -> Int
@// Returns the sum of two integers.

Go to Definition

Jump to where a symbol is defined:

• F12 or Ctrl+Click — Go to definition
• Ctrl+Alt+Click — Go to type definition

Find References

Find all references to a symbol:

• Shift+F12 — Find all references
• F2 — Rename symbol

Diagnostics

Real-time error and warning reporting:

• Type errors
• Unused variables
• Missing fields
• Unreachable code

Code Actions

Quick fixes and refactorings:

• Add missing imports
• Generate record fields
• Implement missing actions
• Fix type mismatches

Code Formatting

Format document or selection:

• Shift+Alt+F — Format document
• Format on save

Signature Help

Parameter hints when calling actions:

@add(|)  @// Shows: add(a: Int, b: Int) -> Int

Document Symbols

Navigate symbols in the file:

• Ctrl+Shift+O — Go to symbol

Workspace Symbols

Search symbols across the project:

• Ctrl+T — Go to symbol in workspace

Code Lens

Inline information:

• Reference counts
• Test status
• Implementation counts

Inlay Hints

Inline type annotations:

@x = 42        @// Shows: @x: Int = 42
@name = "Alice" @// Shows: @name: String = "Alice"

Semantic Tokens

Syntax highlighting with semantic information:

• Variables
• Types
• Actions
• Keywords
• Comments

Editor Setup

VS Code

Install the Draft extension:

code --install-extension draft-lang.draft

Or search for “Draft” in the extension marketplace.

Features:

• Syntax highlighting
• Code completion
• Error checking
• Formatting
• Debugging
• Testing

Neovim

Using nvim-lspconfig:

require'lspconfig'.draft_lsp.setup{}

Using coc.nvim:

{
    "languageserver": {
        "draft": {
            "command": "draft",
            "args": ["lsp"],
            "filetypes": ["draft"],
            "rootPatterns": ["draft.toml"]
        }
    }
}

Vim

Using vim-lsp:

if executable('draft')
    augroup lsp_draft
        autocmd!
        autocmd User lsp_setup call lsp#register_server({
            \ 'name': 'draft',
            \ 'cmd': {server_info -> ['draft', 'lsp']},
            \ 'allowlist': ['draft'],
            \ })
    augroup END
endif

Emacs

Using lisp-mode:

(use-package lsp-draft
    :ensure t
    :hook (draft-mode . lsp))

Sublime Text

Install using Package Control:

1. Ctrl+Shift+P — Command Palette
2. “Package Control: Install Package”
3. “Draft”

Or manually:

{
    "clients": {
        "draft": {
            "command": ["draft", "lsp"],
            "enabled": true,
            "languageId": "draft",
            "scopes": ["source.draft"],
            "syntaxes": ["Packages/Draft/Draft.sublime-syntax"]
        }
    }
}

IntelliJ IDEA / CLion

Install the Draft plugin:

1. Settings → Plugins → Marketplace
2. Search “Draft”
3. Install and restart

Configuration

draft.toml

[lsp]
inlay_hints = true
code_lens = true
semantic_tokens = true
diagnostics = true
completion_snippets = true

VS Code Settings

{
    "draft.lsp.path": "draft",
    "draft.lsp.inlayHints": true,
    "draft.lsp.codeLens": true,
    "draft.lsp.semanticTokens": true,
    "draft.format.enable": true,
    "draft.format.onSave": true
}

Server Options

draft lsp [options]

Options:

• --stdio — Use stdio transport (default)
• --tcp <port> — Use TCP transport
• --pipe <name> — Use named pipe
• --log <level> — Log level (error, warn, info, debug, trace)
• --log-file <path> — Log file path

Protocol Support

The Draft LSP implements the Language Server Protocol 3.17:

Feature	Status
textDocument/completion	Full
textDocument/hover	Full
textDocument/definition	Full
textDocument/references	Full
textDocument/diagnostic	Full
textDocument/codeAction	Full
textDocument/formatting	Full
textDocument/signatureHelp	Full
textDocument/documentSymbol	Full
textDocument/rename	Full
textDocument/inlayHint	Full
textDocument/semanticTokens	Full
textDocument/codeLens	Full
workspace/symbol	Full
workspace/didChangeWatchedFiles	Full

Troubleshooting

LSP Not Starting

@// Check installation
draft lsp --version

@// Check logs
draft lsp --log debug --log-file lsp.log

No Completions

@// Ensure project is initialized
draft init

@// Check draft.toml exists
ls draft.toml

High CPU Usage

@// Disable expensive features
[lsp]
semantic_tokens = false
code_lens = false

Performance

Metric	Value
Startup time	< 100ms
Completion latency	< 50ms
Memory usage	~50 MB
Index time (10k LOC)	< 2s