# Migration Modernization

> Modernize legacy code or frameworks incrementally while preserving behavior, interoperability, and delivery velocity.

- Skill: `nafeeur/migration-modernization` (Agent Skill)
- Install (CLI): `npx skillmds@latest add nafeeur/migration-modernization`
- Raw SKILL.md: https://api.skillmd.com/api/skills/nafeeur/migration-modernization/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: nafeeur (https://skillmd.com/u/nafeeur)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/nafeeur/migration-modernization

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# Migration and Modernization

- Inventory compatibility constraints, generated interfaces, deployment environments, and consumers.
- Add characterization tests around behavior that must survive.
- Define seams and migrate vertical slices behind compatible interfaces.
- Keep old and new paths observable during transition; avoid dual writes without reconciliation.
- Remove legacy code only after usage and rollback windows are understood.
- Measure build, runtime, and maintenance impact after each phase.