Ruby

Debugger: rdbg (Ruby debug gem) Status: Stable Ruby version: 3.1+

Prerequisites

The debug gem ships built-in with Ruby 3.1+. For older versions:

gem install debug

Verify: rdbg --version

Quick Start

# Debug a script
krometrail launch "ruby app.rb" --break app.rb:42

# Debug with bundler
krometrail launch "bundle exec ruby app.rb" --break lib/order.rb:147

# Debug RSpec tests
krometrail launch "bundle exec rspec spec/order_spec.rb" --break lib/order.rb:147

# Debug Rails
krometrail launch "bundle exec rails server" --break app/controllers/orders_controller.rb:55

How It Works

The adapter launches rdbg --open --port PORT to start a DAP server, then connects to it. Your program runs under rdbg, which handles breakpoints and step execution via the standard DAP protocol.

Conditional Breakpoints

Ruby expressions work directly in conditions:

krometrail break "lib/order.rb:147 when discount < 0"
krometrail break "lib/loop.rb:25 when i == 99"

Inspecting Ruby Objects

The viewport renders Ruby objects using inspect:

Locals:
  discount  = -149.97
  order     = #<Order:0x000... id=482, total=149.97, tier="gold">
  items     = Array(3): [#<Item price=49.99>, ...]
  result    = nil

Tips

• Use bundle exec when your project uses Bundler to ensure the correct gem versions are loaded
• The debug gem supports Ruby 3.1+ natively; on older Rubies install the debug gem explicitly
• debug_evaluate accepts any valid Ruby expression including method calls and blocks