BMAD-METHOD/docs/how-to/brownfield/index.md

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Brownfield Development How to use BMad Method on existing codebases

Use BMad Method effectively when working on existing projects and legacy codebases.

What is Brownfield Development?

Brownfield refers to working on existing projects with established codebases and patterns, as opposed to greenfield which means starting from scratch with a clean slate.

This guide covers the essential workflow for onboarding to brownfield projects with BMad Method.

:::note[Prerequisites]

  • BMad Method installed (npx bmad-method install)
  • An existing codebase you want to work on
  • Access to an AI-powered IDE (Claude Code, Cursor, or Windsurf) :::

Step 1: Clean Up Completed Planning Artifacts

If you have completed all PRD epics and stories through the BMad process, clean up those files. Archive them, delete them, or rely on version history if needed. Do not keep these files in:

  • docs/
  • _bmad-output/planning-artifacts/
  • _bmad-output/implementation-artifacts/

Step 2: Maintain Quality Project Documentation

Your docs/ folder should contain succinct, well-organized documentation that accurately represents your project:

  • Intent and business rationale
  • Business rules
  • Architecture
  • Any other relevant project information

For complex projects, consider using the document-project workflow. It offers runtime variants that will scan your entire project and document its actual current state.

Step 3: Get Help

Get help to know what to do next based on your unique needs

Run bmad-help to get guidance when you are not sure what to do next.

Choosing Your Approach

You have two primary options depending on the scope of changes:

Scope Recommended Approach
Small updates or additions Use quick-flow-solo-dev to create a tech-spec and implement the change. The full four-phase BMad method is likely overkill.
Major changes or additions Start with the BMad method, applying as much or as little rigor as needed.

During PRD Creation

When creating a brief or jumping directly into the PRD, ensure the agent:

  • Finds and analyzes your existing project documentation
  • Reads the proper context about your current system

You can guide the agent explicitly, but the goal is to ensure the new feature integrates well with your existing system.

UX Considerations

UX work is optional. The decision depends not on whether your project has a UX, but on:

  • Whether you will be working on UX changes
  • Whether significant new UX designs or patterns are needed

If your changes amount to simple updates to existing screens you are happy with, a full UX process is unnecessary.

Architecture Considerations

When doing architecture, ensure the architect:

  • Uses the proper documented files
  • Scans the existing codebase

Pay close attention here to prevent reinventing the wheel or making decisions that misalign with your existing architecture.

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