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The lsp command manages the Gleeb Language Server Protocol (LSP) server, which provides IDE features like autocomplete, error checking, and code navigation for Fern development.

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Usage

fern lsp <command> [options]

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Commands

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start

Start the Gleeb LSP server: 
fern lsp start [options]
​
--background
flag
Run server in background (daemon mode)
​
-b
flag
Short form of --background
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--port
number
TCP port to listen on (otherwise uses stdio)
Examples: 
# Start in foreground (for debugging)
fern lsp start

# Start in background
fern lsp start --background

# Start on specific port
fern lsp start --port 9000 --background

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stop

Stop the running LSP server: 
fern lsp stop

LSP server stopped

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status

Show LSP server status and configuration: 
fern lsp status

LSP Server Status
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Gleeb LSP installed: Yes
Server path: ~/.fern/gleeb/dist/server.js
Server running: Yes
Process ID: 12345
VS Code configured: Yes
Node.js available: Yes

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config

Configure editor integration: 
fern lsp config [options]
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--editor
string
default:"vscode"
Editor to configure (currently only vscode supported)
Example: 
fern lsp config --editor vscode

Configuring VS Code for Gleeb LSP...

VS Code configured successfully
Install the 'Gleeb LSP for Fern UI' extension from VS Code marketplace
Extension ID: fernkit.gleeb-lsp

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install

Install or reinstall the Gleeb LSP server: 
fern lsp install

Installing Gleeb LSP...
Production mode: Cloning from GitHub

Cloning Gleeb LSP from GitHub...
Copying to ~/.fern/gleeb...
Installing dependencies...
Building LSP server...
Created launcher script

Gleeb LSP installed successfully

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restart

Restart the LSP server: 
fern lsp restart
Equivalent to running stop then start --background.

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Installation

The LSP server must be installed before use: 
fern lsp install
This:
  1. Clones Gleeb LSP from GitHub (or uses local copy if in development)
  2. Installs Node.js dependencies
  3. Builds the TypeScript source
  4. Creates launcher scripts in ~/.local/bin/

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IDE Integration

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VS Code

1

Install LSP server

fern lsp install
2

Configure VS Code

fern lsp config --editor vscode
3

Install VS Code extension

Open VS Code and install the “Gleeb LSP for Fern UI” extension:
Ctrl+P → ext install fernkit.gleeb-lsp
4

Start LSP server

fern lsp start --background
The extension provides:
  • Autocomplete - Code completion for Fern APIs
  • Error checking - Real-time syntax and type errors
  • Go to definition - Jump to function/class definitions
  • Hover information - Documentation on hover
  • Code formatting - Automatic code formatting

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Manual Configuration

If automatic configuration doesn’t work, add to VS Code settings.json: 
{
  "gleeb.enable": true,
  "gleeb.serverPath": "~/.fern/gleeb/dist/server.js",
  "gleeb.trace.server": "verbose"
}

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Server Modes

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Stdio Mode (Default)

Server communicates over stdin/stdout: 
fern lsp start --background
Used by most editors/IDEs.

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TCP Mode

Server listens on a network port: 
fern lsp start --port 9000 --background
Useful for:
  • Remote development
  • Debugging
  • Multiple client connections

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Requirements

The LSP server requires:
  • Node.js (v14 or later)
  • npm (comes with Node.js)
  • Git (for installation)
Check with: 
node --version
npm --version
git --version
Install Node.js from nodejs.org if needed.

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Server Locations

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~/.fern/gleeb/
directory
LSP server installation directory
​
~/.fern/gleeb/dist/server.js
file
Compiled LSP server executable
​
~/.fern/gleeb/server.pid
file
Process ID file (when running in background)
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~/.local/bin/gleeb-lsp
file
Launcher script for manual server startup

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Development Mode

When developing Fern itself: 
# Use local Gleeb sources
cd /path/to/fern
fern lsp install  # Detects and uses local gleeb/ directory

# Changes to gleeb/ source
cd gleeb
npm run build

# Restart server to use new build
fern lsp restart

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Troubleshooting

fern lsp install
# Error: Node.js not found
Solution: Install Node.js from nodejs.org:
# Ubuntu/Debian
curl -fsSL https://deb.nodesource.com/setup_18.x | sudo -E bash -
sudo apt-get install -y nodejs

# Fedora
sudo dnf install nodejs
Check the status:
fern lsp status
Try reinstalling:
fern lsp stop
rm -rf ~/.fern/gleeb
fern lsp install
fern lsp start --background
  1. Verify server is running: 
    fern lsp status
  2. Check VS Code output panel:
    • View → Output
    • Select “Gleeb LSP” from dropdown
  3. Restart VS Code and the LSP server: 
    fern lsp restart

fern lsp install
# Error: npm run build failed
Solution: Check npm dependencies:
cd ~/.fern/gleeb
rm -rf node_modules package-lock.json
npm install
npm run build

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Features

The Gleeb LSP provides:

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Code Completion

  • API method suggestions
  • Parameter hints
  • Import suggestions
  • Fern namespace completion

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Diagnostics

  • Syntax errors
  • Type errors
  • Undefined reference warnings
  • Best practice suggestions

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Code Navigation

  • Go to definition
  • Find references
  • Workspace symbol search
  • Document outline

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Documentation

  • Hover documentation
  • Signature help
  • Parameter documentation
  • Example code snippets

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Manual Server Control

The LSP can also be started manually: 
# Using launcher script
~/.local/bin/gleeb-lsp

# Direct Node.js invocation
cd ~/.fern/gleeb
node dist/server.js --stdio

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Logs

View server logs for debugging: 
# Foreground mode logs to console
fern lsp start

# Background mode logs to file
tail -f ~/.fern/gleeb/server.log

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Updating

To update to the latest version: 
# Reinstall from GitHub
fern lsp stop
fern lsp install
fern lsp start --background

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