Plumbo

A zero-config development panel that lists every file behind the page you're looking at — controller, helper, layout, templates, partials, and the Stimulus controllers in use — so you can copy their paths straight into an AI assistant.

Paths copy @-prefixed (e.g. @app/views/posts/index.html.erb), ready to paste as file mentions. Plumbo is self-contained: a Rack middleware injects its own HTML, CSS, and JavaScript — nothing is added to your asset pipeline, and there are no view, layout, or bundler changes. Drop it into any Rails app.

Install

# Gemfile
group :development do
  gem "plumbo"
end

bundle install

That's it. Boot your app in development and a badge appears in the bottom-right showing how many files rendered the current page.

Using the panel

  • Click the badge to open the list — a tree, in render order, with partials and Stimulus controllers nested (and color-coded) under their parent.
  • Collapse or expand a parent by clicking its row; copy a single path with its copy icon, or Copy All for the whole (filtered) list.
  • Filter by typing in the search box, or click a type chip — Controllers, Views, Partials, Stimulus, … — to show just one kind.
  • Clear All empties the list so you can watch fresh files appear as you click around. The list keeps up with Turbo (Drive, Frames, and Streams) without a full page reload.

Configuration

Defaults are dev-only and need no setup. To override, add an initializer:

# config/initializers/plumbo.rb
Plumbo.configure do |c|
  c.enabled          = Rails.env.development?  # default: true only in development
  c.path_prefix      = "@"                     # default "@"; set "" for bare paths
  c.max_files        = 500                     # safety cap on listed files
  c.include_stimulus = true                    # list Stimulus controllers
  c.javascript_root  = "app/javascript"        # source dir Stimulus paths map into
end

How it works

A Railtie inserts a Rack middleware that subscribes to ActionView's render notifications for each request, collecting every file under your app root in call order. It also scans rendered templates for data-controller attributes and maps each to its Stimulus source file. The panel is injected into full HTML pages, and every response carries an X-Plumbo-Files header that the panel reads on each fetch to stay current across Turbo navigations.

Only Stimulus controllers written as data-controller in a rendered .erb are detected — those emitted by helpers or ViewComponents, and other JavaScript, aren't listed.

Notes

  • Production-safe: disabled outside development by default.
  • Icons from Lucide (ISC license).

License

MIT — see LICENSE.txt.