Designs incremental migration strategies, identifies service boundaries, produces dependency maps and migration roadmaps, and generates API facade designs for aging codebases. Use when modernizing legacy systems, implementing strangler fig pattern or branch by abstraction, decomposing monoliths, upgrading frameworks or languages, or reducing technical debt without disrupting business operations.
Install
npx skills add Jeffallan/claude-skills --skill legacy-modernizernpx skills add Jeffallan/claude-skills --skill legacy-modernizer -a claude-code -gnpx skills add Jeffallan/claude-skills --skill legacy-modernizer -a codex -ggemini skills install https://github.com/Jeffallan/claude-skills.git --path skills/legacy-modernizergh skill install Jeffallan/claude-skills legacy-modernizergit clone --depth 1 https://github.com/Jeffallan/claude-skills /tmp/Jeffallan__claude-skills
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/Jeffallan__claude-skills/skills/legacy-modernizer ~/.claude/skills/legacy-modernizer # Claude Code
cp -R /tmp/Jeffallan__claude-skills/skills/legacy-modernizer ~/.agents/skills/legacy-modernizer # Codex, Cursor, Gemini CLI, Copilot, OpenCode