493: Suspenders with Steve Polito

What It Covers

Steve Polito discusses the major rewrite of Suspenders, Thoughtbot's Rails application generator gem that existed since 2008. The conversation covers using AI for onboarding, the technical architecture shift from Rails engine to application template, and how the gem packages Thoughtbot's Rails conventions including RSpec, FactoryBot, Heroku deployment, and strong migrations into a single command.

Key Questions Answered

• •AI-Assisted Onboarding: Use Claude in plan mode to identify which existing specs to examine first when starting new projects, rather than having it write code directly. Ask the AI to flip the script and question your feature approach, then distill those questions for stakeholders across time zones, reducing wait time from hours to minutes while maintaining human validation.
• •Consultants as Question Askers: Professional consulting centers on asking the right questions early, especially for new features that establish future patterns. Use AI to surface edge cases and considerations not in acceptance criteria, then validate with product stakeholders. Understanding what you don't know matters more than demonstrating existing knowledge, particularly when onboarding to unfamiliar domains.
• •Suspenders Architecture Evolution: The gem shifted from inheriting Rails generator classes to becoming a simple wrapper for Rails new that passes three options: Postgres database, skip test framework, and an application template file. This rewrite removed 5,000 lines of code, added 1,000, and reduced generation time to eight seconds while making contributions significantly easier.
• •CI Testing Generated Apps: Configure continuous integration to actually run suspenders new, generate an app, scaffold a resource, and execute the test suite inside the generated application. This prevents the common failure mode where the gem's tests pass but apps generated by the tool have broken CI, ensuring end users receive working applications from day zero.
• •Two-Commit Audit Trail: Generate an initial commit containing everything Rails new produces, followed by a second commit showing only suspenders modifications. This creates a clear diff for teams to audit what the gem adds, enables easy customization of specific settings, and provides valuable context for future git blame investigations when questioning configuration choices months later.