code-modernization

A structured toolkit for updating old software, such as COBOL, legacy Java, C++, .NET, or monolithic web applications. It guides the work from understanding the existing system through redesign, code changes, and hardening.

In plain words
What is it for?
Use it to assess a legacy codebase, map its structure, extract business rules, plan a rewrite or upgrade, transform code, and check the result.
Why use it?
It gives teams a defined way to understand complicated older systems before changing them. It also supports moving to a different technology, redesigning the system, or upgrading it within the same technology family.

Plugin for Claude Code

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add plugins/anthropics/claude-plugins-official/code-modernization
Claude Code
/plugin marketplace add anthropics/claude-plugins-official
Clone the repo
git clone --depth 1 https://github.com/anthropics/claude-plugins-official

Made for: Claude Code.

Per session not measured What this adds to a session before it is invoked.
When invoked not measured Not applicable: nothing here is loaded into a session.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Security

Grade A, and why

code-modernization scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

plugins/code-modernization/.claude-plugin/plugin.json · 9 lines

What it actually says

{
  "name": "code-modernization",
  "description": "Modernize legacy codebases (COBOL, legacy Java/C++/.NET, monolith web apps) with a structured preflight / assess / map / extract-rules / brief / (reimagine | transform | uplift) / harden / status workflow. Cross-stack rewrites, greenfield reimagining, and same-stack version uplifts (e.g. .NET Framework → .NET 8); an interactive topology viewer; specialist agents; and optional dynamic-workflow orchestration with adversarial verification.",
  "author": {
    "name": "Anthropic",
    "email": "[email protected]"
  }
}
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 9 lines scan A ad13ae6855d8

Subscribe to this mod's changes

code-modernization is a plugin published in the GitHub repository anthropics/claude-plugins-official (35,577 stars, last pushed 3d ago), licensed Apache-2.0. Its token cost is not measured: this kind of file is read by the harness, not the model. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.