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How to Add a Feature to an Existing Project

Add new functionality to your brownfield codebase while respecting existing patterns and architecture.

When to Use This

Adding a new feature to an existing codebase
Major enhancements that need proper planning
Features that touch multiple parts of the system

Prerequisites

BMad Method installed
Existing project documentation (run document-project first if needed)
Clear understanding of what you want to build

Steps

1. Run workflow-init

Run workflow-init

The workflow should recognize you’re in an existing project. If not, explicitly clarify that this is brownfield development.

2. Choose Your Approach

Feature Scope	Recommended Approach
Small (1-5 stories)	Quick Flow with tech-spec
Medium (5-15 stories)	BMad Method with PRD
Large (15+ stories)	Full BMad Method with architecture

3. Create Planning Documents

For Quick Flow:

Load PM agent
Run tech-spec workflow
The agent will analyze your existing codebase and create a context-aware spec

For BMad Method:

Load PM agent
Run PRD workflow
Ensure the agent reads your existing documentation
Review that integration points are clearly identified

4. Consider Architecture Impact

If your feature affects system architecture:

Load Architect agent
Run architecture workflow
Ensure alignment with existing patterns
Document any new ADRs (Architecture Decision Records)

5. Implement

Follow the standard Phase 4 implementation workflows:

sprint-planning - Organize your work
create-story - Prepare each story
dev-story - Implement with tests
code-review - Quality assurance

Tips

Always ensure agents read your existing documentation
Pay attention to integration points with existing code
Follow existing conventions unless deliberately changing them
Document why you’re adding new patterns (if any)