Code Modernization plugin: what it installs and how to add it

Point Claude at a legacy codebase to assess its structure, dependencies, security risks and business rules before choosing an upgrade, rewrite or rebuild. The workflow produces an interactive map, a phased plan for approval and Given/When/Then rules, then independently checks that the modernised code behaves like the original.

Use it when taking on an unfamiliar system or planning a controlled migration. It works with any language, leaves the legacy source untouched and writes analysis and modernised code to separate locations. Install it in Claude Code with /plugin install code-modernization@claude-plugins-official.

What's inside

• 13 slash commands: /modernize, /modernize-preflight, /modernize-status, /modernize-assess, /modernize-map, /modernize-extract-rules, /modernize-review, /modernize-brief, /modernize-uplift, /modernize-transform, /modernize-reimagine, /modernize-verify and /modernize-harden
• 8 specialist agents: architecture critic, business rules extractor, legacy analyst, scaffolder, security auditor, test engineer, uplift migrator and version delta analyst
• 6 hooks, with no skills or MCP servers