Chapter 7 - Large Feature Development
Implement multi-file changes using AI assistance to plan, execute, and test complex features across a full-stack application.
- Reading time: 45 minutes
- Practical time: 6-8 hours (full day)
Reading
Briefs
Assets
Feature stories and requirements:
- Download: 07-large-feature-development.tar.gz
⚠️ Important: These assets contain feature stories and requirements. No configuration files need to be overwritten for this chapter.
Practical
Task: Implement a Large Feature
Choose one story from the list below. Each story includes functional requirements, technical requirements, and acceptance criteria.
Choosing a Story
All stories are available in the Assets section above.
| Story | Complexity | Stack |
|---|---|---|
| UI Internationalization (i18n) | Moderate | Frontend |
| Accessibility Menu | Moderate | Frontend |
| Image Upload Support | High | Full-stack |
| Order Status Workflow | High | Full-stack |
| Real-Time Product Updates | High | Full-stack |
| Docker Images | Moderate | DevOps |
| Keycloak OAuth Authentication | High | Full-stack |
| Multi-Location Fulfillment Strategy | Moderate | Backend |
| NgRx SignalStore Migration | High | Frontend |
Recommended for first attempt: UI Internationalization - moderate complexity
Workflow
For your chosen story, follow these steps:
- Read the story: Understand the functional and technical requirements, scope, and acceptance criteria
- Explore options: Discuss implementation approaches with the agent (pros, cons, trade-offs for a small project)
- Research libraries: Identify production-ready options for the technical decisions in your story
- Create a plan: Break the work into phases with clear milestones
- Implement incrementally: Complete one phase at a time. Commit after each phase.
- Test thoroughly: Run manual tests and automated tests. Verify each acceptance criterion is met
What to Observe
- How agents help break down requirements into implementation steps
- Planning and architectural decision support quality
- Managing multi-file changes with version control
- When you need to steer the agent vs. when it makes good decisions independently
Continue with: Spec-Driven Agentic Coding with OpenSpec — learn how to use structured change proposals (/opsx:propose → review → /opsx:apply → /opsx:archive) to drive AI agents through larger features with more consistency.