Linux command-line essentials for everyday file, process, package, SSH, and shell tasks, plus editor setup, shortcuts, permissions, and executable scripts.

Exception notifications help detect application errors early, but naïve e-mail alerts can flood inboxes and repeat the same issue across servers. Sentry reduces noise by aggregating similar errors and suppressing duplicates.

Pagination keeps large movie lists responsive by loading only a page of records instead of thousands at once. will_paginate adds page links and reduces render time.

BEM brings consistent, reusable CSS structure to new and legacy projects, making block-based styling easier to maintain and reuse across screens.

Rails migration exercises for adding cached actor fields and backfilling existing records, with guidance on complex migrations and avoiding model usage in migrations.

ActiveRecord-style file uploads with image resizing, cropping, validation, caching, and forced downloads for movie posters in Rails using CarrierWave.

Real-browser integration tests with Capybara and Selenium often become flaky because of driver differences, JavaScript dialogs, cookies, downloads, and browser state.

Advanced Git workflows for rewriting history, splitting commits, rebasing branches, and handling remote pushes, conflicts, and recovery after mistakes.

Event bubbling and delegation reduce handler count while affecting propagation control and dynamically created elements. stopPropagation(), stopImmediatePropagation() and preventDefault() behave differently.

Reusable JavaScript components need clear scope, multiple instances, dynamic activation, and cleanup to avoid brittle page-specific behavior.

Views grow. The same card, button or navigation shows up on ten screens, and soon the same twelve lines of HTML live in ten places. Rails partials are the first tool against this; ViewComponent is the second, for components that carry logic, helpers, CSS and JavaScript of their own. This card teaches you to give your views a small, readable vocabulary of components.

Important

Work on this lesson in advisor mode.

Learning goals

• You can explain how a partial exposes an API to its callers: through locals, and by accepting a bloc...

Cookies and Rails sessions differ in scope, lifetime, and security properties. Signed, encrypted, and SameSite cookies shape how state survives requests and browser storage.

Web application security centers on common attack vectors, Rails protections, dependency checks, and HTTPS limits for preventing XSS, CSRF, SQL injection, and session theft.

User identity verification in Rails needs secure session handling and password storage; Clearance or Devise avoid custom authentication pitfalls while supporting sign-in, sign-out, and protected pages.

Fine-grained access control in Rails can depend on role, ownership, and per-resource permissions. Consul and assignable_values help model custom authorization rules and restricted choices in forms.

Rails nested attributes keep child records in one transaction, while form helpers encode names so additions, removals, and ignored blank entries map correctly.

Associations need a deletion strategy when parent records disappear; :dependent and soft-delete choices affect data integrity, forms, and validations for related users and movies.

Form models separate user-facing input handling from domain models, especially for sign-up, login, and merge screens. They help manage validation and interaction-specific code without overloading ActiveRecord.

Rails ships with a default menu of libraries and conventions — its creators call it "Omakase", the chef's choice. Like many companies, we don't follow that menu blindly. Over the years we have adjusted our stack to our own taste and experience. This card explains where we differ and why, so you won't be confused when a tutorial, a Rails guide or a freshly generated app looks different from our projects.

Important

Work on this lesson in teacher mode.

Learning goals

• You can explain what "Omakase" means in Rails and why a compan...

Regular expressions can extract structured data from simple Ruby code, including class names, superclasses, and methods, when a full parser would be overkill.

Software design review topics focus on code smells, technical debt, and architecture antipatterns in existing repos such as Cards and MovieDB.

Browser support varies for HTML, CSS, and JavaScript features; older Safari lags, and BrowserStack, feature detection, transpilation, and polyfills help keep apps working.

Rails frontend asset systems differ in bundling, fingerprinting, package support, and postprocessing; esbuild is the current preferred approach, while Sprockets and Webpacker remain relevant in older apps.

So far, others have reviewed your code. From now on you will also review code yourself: your colleagues' merge requests and — more and more — code that an agent wrote for you. Reviewing is a skill of its own. This lesson teaches you what to look for, how to write useful comments, and what is different about reviewing agent-generated code.

Important

Work on this lesson in advisor mode.

Learning goals

• You can explain what a code review is for: a code base that gets better over time, knowledge that spreads, bugs caught before us...