name: evolution

description: Add features to existing products through targeted changes

[E] Evolution — Add Features to Existing Product

Goal: Incrementally add features to an existing product with minimal disruption.

When to use: Existing product needs new functionality. Changes should be targeted, not a complete rewrite.

Backward compatible — Existing functionality must keep working. Every change is verified against what already exists.
Feature flags if needed — When a change is risky or requires staged rollout, use feature flags to decouple deployment from activation.
Incremental delivery — Ship in small, verifiable increments. Each commit should leave the system in a working state.

Read {output_folder}/_progress/00-design-log.md. Check Current and Backlog for context.

Execute steps in ./steps-e/:

Step	File	Purpose
01	step-01-scope-change.md	Define what changes vs what stays
02	step-02-analyze-impact.md	Analyze impact on existing code
03	step-03-plan-implementation.md	Plan incremental implementation
04	step-04-implement.md	Implement changes
05	step-05-verify-and-document.md	Verify, regression check, document

Flow: 01 → 02 → 03 → 04 → 05

ALWAYS map what is new vs what is modified vs what is untouched before coding
ALWAYS capture baseline state of existing features before modifying them
ALWAYS verify backward compatibility at each commit
ALWAYS plan incremental commits — never one giant change
NEVER break existing functionality to add new functionality
NEVER skip impact analysis — surprises in production are expensive

Append a progress entry to {output_folder}/_progress/00-design-log.md under ## Progress: ### [date] — Evolution: [what was evolved/added]
Suggest acceptance testing (Phase 5 [T]) to validate the changes