Agent Plugin
Code Modernization
Assess legacy systems, map architecture and business rules, plan modernization, and verify rewrites or version uplifts against existing behavior.
What is Code Modernization?
Code Modernization is Anthropic's structured Claude Code plugin for legacy transformation. It forces discovery before implementation, creates architecture and business-rule artifacts, distinguishes rewrite from version uplift, and uses test harnesses and specialist review to show whether behavior has drifted.
Key capabilities
Evidence-first discovery
Produces assessments, dependency maps, business-rule cards, and a reviewed brief before code transformation begins.
Multiple migration strategies
Supports reimagining, targeted cross-stack transformation, and same-stack uplift as separate, explicit workflows.
Use cases
Plan a legacy migration
Build an evidence-backed modernization brief from code structure, dependencies, rules, and operational constraints.
Prove a transformation
Execute a selected migration path and compare the result against characterized legacy behavior.
Included components
Commands
modernize-assess
modernize-map
modernize-extract-rules
modernize-transform
modernize-uplift
Agents
architecture-critic
Installation scope
- Claude Code
- A locally inspectable legacy codebase