Tutorial Quickstart

Tutorial Quickstart

End-to-end guide: scaffold a project, write your first lesson, and deploy.

Step 1: Scaffold

npx create-tutorialkit-rb my-tutorial

The CLI prompts for:

Skip all prompts with --defaults, or pass flags directly:

npx create-tutorialkit-rb my-tutorial -p pnpm --provider netlify --git

What Gets Created

my-tutorial/
├── src/
│   ├── content/tutorial/        ← Your tutorial content goes here
│   │   ├── meta.md              ← Tutorial root config (already set up)
│   │   └── 1-getting-started/   ← Sample part with starter lessons
│   ├── templates/default/       ← WebContainer runtime (don't modify)
│   └── components/              ← UI components
├── ruby-wasm/
│   └── Gemfile                  ← Add gems here, then rebuild WASM
├── bin/build-wasm               ← Rebuilds the WASM binary
├── astro.config.ts
└── package.json

Step 2: Add Your Gems

Edit ruby-wasm/Gemfile to include the gems your tutorial needs:

# ruby-wasm/Gemfile
source "https://rubygems.org"

gem "wasmify-rails", "~> 0.4.0"
gem "rails", "~> 8.0.0"

# Your tutorial's gems
gem "action_policy"
gem "devise"

Then build the WASM binary:

npm run build:wasm    # Takes up to 20 minutes on first run

Subsequent rebuilds are faster thanks to caching, but still take a few minutes.

Step 3: Start the Dev Server

npm run dev           # Starts at http://localhost:4321/

The sample tutorial loads immediately. You'll see the starter lessons from the scaffold.

Step 4: Write Your First Lesson

4a. Create the Directory Structure

src/content/tutorial/
├── meta.md                              ← Already exists (tutorial root)
└── 1-basics/
    ├── meta.md                          ← Part metadata
    └── 1-hello-rails/
        ├── content.md                   ← Your lesson
        ├── _files/                      ← Starting code
        │   └── workspace/
        │           └── app/
        │               └── controllers/
        │                   └── pages_controller.rb
        └── _solution/                   ← Solution code
            └── workspace/
                    └── app/
                        └── controllers/
                            └── pages_controller.rb

4b. Write the Part Metadata

# src/content/tutorial/1-basics/meta.md
---
type: part
title: The Basics
---

4c. Write the Lesson

# src/content/tutorial/1-basics/1-hello-rails/content.md
---
type: lesson
title: Hello Rails
focus: /workspace/app/controllers/pages_controller.rb
previews: [3000]
mainCommand: ['node scripts/rails.js server', 'Starting Rails server']
prepareCommands:
  - ['npm install', 'Preparing Ruby runtime']
  - ['node scripts/rails.js db:prepare', 'Prepare development database']
terminalBlockingPrepareCommandsCount: 2
custom:
  shell:
    workdir: '/workspace'
---

# Hello Rails

Open `app/controllers/pages_controller.rb` and add a `home` action:

\`\`\`ruby title="app/controllers/pages_controller.rb" ins={2-4}
class PagesController < ApplicationController
  def home
    render plain: "Hello from Rails on WebAssembly!"
  end
end
\`\`\`

Visit the preview to see your message.

4d. Add Starting Files

Put a skeleton file in _files/:

# _files/workspace/app/controllers/pages_controller.rb
class PagesController < ApplicationController
  # Add your action here
end

4e. Add Solution Files

Put the completed code in _solution/:

# _solution/workspace/app/controllers/pages_controller.rb
class PagesController < ApplicationController
  def home
    render plain: "Hello from Rails on WebAssembly!"
  end
end

4f. Delete the Sample Content

Remove the scaffold's starter lessons once you have your own:

rm -rf src/content/tutorial/1-getting-started/
rm -rf src/content/tutorial/2-controllers/

The rails-app Template

The scaffold includes a pre-built rails-app template at src/templates/rails-app/ with authentication, styling, and seed data ready to go. Most tutorials should extend this template rather than building from scratch.

What's Included

• Authentication — session-based login via Authentication concern (app/controllers/concerns/authentication.rb)
• Quick login — password-free login buttons on the sign-in page for tutorial convenience
• CSS design system — modern BEM-based stylesheet with CSS custom properties
• Seed users — Alice and Bob created in db/seeds.rb
• Layout — nav bar with brand, user name, login/logout; flash messages; .container wrapper

Authentication Flow

The template uses Rails 8's authentication generator pattern:

• Authentication concern adds require_authentication as a before_action
• Controllers opt out with allow_unauthenticated_access
• Current.user is available everywhere via Current.session.user
• authenticated? helper works in both controllers and views

Quick login lets tutorial users sign in with one click instead of typing credentials:

• SessionsController#new populates @preauthenticate_users (all users by default)
• SessionsController#preauthenticate logs in by user ID (no password)
• The sessions/_preauthenticate_user.html.erb partial renders each quick-login button
• Route: post :preauthenticate, on: :collection under resource :session

To customize quick-login users in a lesson, override the sessions controller in _files/:

# _files/workspace/app/controllers/sessions_controller.rb
class SessionsController < ApplicationController
  allow_unauthenticated_access only: %i[new create preauthenticate]

  def new
    # Show only specific users for this lesson
    @preauthenticate_users = User.where(role: "agent").order(:name)
  end
  # ... rest inherited from template
end

CSS Design System

The template's application.css uses pure CSS with custom properties and BEM naming. Use these classes in your lesson ERB files — no extra setup needed.

CSS Custom Properties (:root variables):

BEM Components:

Customizing the Demo App for Your Domain

To turn the generic demo app into your tutorial's domain (e.g., a Help Desk, a Store, etc.):

1. Rename the app module in config/application.rb:

module Helpdesk  # was DemoApp
  class Application < Rails::Application

2. Add your models. Create migrations in db/migrate/ and models in app/models/. Update db/schema.rb to match.

3. Add controllers and views. Put CRUD controllers in app/controllers/ and ERB views in app/views/. Use the BEM classes from the CSS design system.

4. Update routes in config/routes.rb.

5. Update seeds in db/seeds.rb with domain-specific sample data. Keep the default password s3cr3t for all users so the quick-login flow works.

6. Update the layout — change the brand name in app/views/layouts/application.html.erb, add nav links for your resources.

7. Update the home page — replace the hero content in app/views/home/index.html.erb.

Step 5: Use a Template for Pre-Built State

If your lesson needs an existing Rails app (not just an empty workspace), create a template:

src/templates/my-app/
├── .tk-config.json          → { "extends": "../default" }
└── workspace/
      ├── app/
      ├── config/
      ├── db/
      └── ...

Then reference it from your lesson's _files/.tk-config.json:

{
  "extends": "../../../../../templates/my-app"
}

See the rails-file-management skill for details on template inheritance.

Step 6: Deploy

Tutorials need Cross-Origin-Embedder-Policy and Cross-Origin-Opener-Policy headers for WebContainers to work. If you chose a hosting provider during scaffold, these are already configured.

Build for Production

npm run build         # Produces a static site in dist/

Manual Header Configuration

If you didn't choose a provider during scaffold, add these headers to every response:

Cross-Origin-Embedder-Policy: require-corp
Cross-Origin-Opener-Policy: same-origin

Vercel (vercel.json)

{
  "headers": [
    {
      "source": "/(.*)",
      "headers": [
        { "key": "Cross-Origin-Embedder-Policy", "value": "require-corp" },
        { "key": "Cross-Origin-Opener-Policy", "value": "same-origin" }
      ]
    }
  ]
}

Netlify (netlify.toml)

[[headers]]
for = "/*"
[headers.values]
Cross-Origin-Embedder-Policy = "require-corp"
Cross-Origin-Opener-Policy = "same-origin"

Cloudflare (public/_headers)

/*
  Cross-Origin-Embedder-Policy: require-corp
  Cross-Origin-Opener-Policy: same-origin

Customizing Look & Feel (Branding)

To match your tutorial's branding to your project's documentation site, update these files:

Logos

Replace public/logo.svg (light mode) and public/logo-dark.svg (dark mode) with your project's logo SVG. Use a dark fill (e.g., #0F4D8A) for the light-mode version and a light fill (e.g., #E4E6E9) for the dark-mode version.

Title in Top Bar

Edit src/components/TopBar.astro — add a <span> after the logo images inside the <a> tag:

<span class="ml-2 text-sm font-medium text-tk-elements-topBar-iconButton-iconColor whitespace-nowrap">
  Your Tutorial Title
</span>

Favicon

Replace public/favicon.svg with your project's icon. Optionally add a public/favicon.ico for broader browser support.

Accent Colors (UnoCSS Theme)

Override the accent palette in uno.config.ts to change buttons, links, active tabs, and badges site-wide:

import { defineConfig } from '@tutorialkit-rb/theme';

export default defineConfig({
  theme: {
    colors: {
      accent: {
        50: '#EFF6FF',
        100: '#E5F0FF',
        200: '#B6D4FF',
        300: '#75B5FF',
        400: '#4DA6FF',   // dark mode accent
        500: '#0E7EF1',   // primary interactive
        600: '#0F4D8A',   // primary brand
        700: '#0C3F72',
        800: '#09325A',
        900: '#072848',
        950: '#041A30',
      },
    },
  },
  content: {
    pipeline: { include: '**' },
  },
});

Generate your scale from your brand's primary color. The 600 slot is the main brand color; 500 is for hover/interactive states; 400 is used in dark mode.

Component Hardcoded Colors

Some components use hardcoded Tailwind color classes instead of theme tokens. Search for and replace these:

• src/components/HelpDropdown.tsx — Reload button uses bg-blue-600. Change to bg-accent-600 hover:bg-accent-700.
• src/components/HeadTags.astro — Rails path link colors. Update hex values to match your brand.

Rails Demo App CSS

Update the primary color in src/templates/rails-app/workspace/app/assets/stylesheets/application.css:

:root {
  --color-primary: #0F4D8A;       /* your brand color */
  --color-primary-hover: #0C3F72; /* darker shade */
  --color-primary-light: #EFF6FF; /* tinted background */
}

OG Meta (Social Sharing Image)

Add Open Graph meta tags so your tutorial shows a rich preview when shared on social media, Slack, etc.

1. Generate a cover image. Use a tool like myogimage.com to create a 1200×630 OG image with your tutorial title and branding.

2. Save it as public/cover.png.

3. Add the meta key to your tutorial root src/content/tutorial/meta.md:

---
type: tutorial
meta:
  image: /cover.png
  title: Your Tutorial Title
  description: |
    A short description of what your tutorial teaches
# ... rest of frontmatter
---

The meta fields map to standard OG tags (og:image, og:title, og:description) and are rendered in <head> automatically by TutorialKit.

GitHub Link

Update the repo URL in src/components/GitHubLink.astro:

<a href="https://github.com/your-org/your-repo" ...>

Common Issues

Next Steps