legacy-modernizer

legacy-modernizer is an agent for Claude Code from rafaelkamimura/claude-tools. It costs 48 tokens per session (242 once invoked), scanned A, a copy of code-refactoring-legacy-modernizer, MIT.

A guide for updating old software systems in small, controlled steps. It covers outdated frameworks, dependencies, databases, and application structures while keeping existing behavior working.

In plain words
What is it for?
It helps plan and carry out framework upgrades, dependency and security updates, monolith splits, test coverage improvements, API compatibility, and gradual replacement of old components.
Why use it?
It reduces the risk of breaking a system while removing technical debt, which is the cost of outdated or hard-to-maintain code.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the claude-tools plugin — 12 commands, 46 agents shipped together

Good fit It helps plan and carry out framework upgrades, dependency and security updates, monolith splits, test coverage improvements, API compatibility, and gradual replacement of old components.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/rafaelkamimura/claude-tools/legacy-modernizer
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.

Clone the repo
git clone --depth 1 https://github.com/rafaelkamimura/claude-tools

Made for: Claude Code.

Or install claude-tools, the plugin that ships this one along with the rest of its 12 commands, 46 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for legacy-modernizer

README.md
[![agentmods](https://agentmods.dev/badge/agents/rafaelkamimura/claude-tools/legacy-modernizer.svg)](https://agentmods.dev/agents/rafaelkamimura/claude-tools/legacy-modernizer)
Your own site
<a href="https://agentmods.dev/agents/rafaelkamimura/claude-tools/legacy-modernizer"><img src="https://agentmods.dev/badge/agents/rafaelkamimura/claude-tools/legacy-modernizer.svg" alt="Measured on agentmods" height="20"></a>
Per session 48 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 242 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 89% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00048 $0.00242
Opus 5 $0.00024 $0.00121
Sonnet 5 $0.00010 $0.00048
Haiku 4.5 $0.00005 $0.00024

Measured 7d ago against content hash ca0ccb94fc2f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

legacy-modernizer 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 7d ago.

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

This is a copy

89% identical to code-refactoring-legacy-modernizer — 7 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

agents/legacy-modernizer.md · 33 lines

What it actually says

You are a legacy modernization specialist focused on safe, incremental upgrades.

Focus Areas

  • Framework migrations (jQuery→React, Java 8→17, Python 2→3)
  • Database modernization (stored procs→ORMs)
  • Monolith to microservices decomposition
  • Dependency updates and security patches
  • Test coverage for legacy code
  • API versioning and backward compatibility

Approach

  1. Strangler fig pattern - gradual replacement
  2. Add tests before refactoring
  3. Maintain backward compatibility
  4. Document breaking changes clearly
  5. Feature flags for gradual rollout

Output

  • Migration plan with phases and milestones
  • Refactored code with preserved functionality
  • Test suite for legacy behavior
  • Compatibility shim/adapter layers
  • Deprecation warnings and timelines
  • Rollback procedures for each phase

Focus on risk mitigation. Never break existing functionality without migration path.

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. 7d ago First seen · 33 lines · 48 tokens per session scan A ca0ccb94fc2f

Subscribe to this mod's changes

legacy-modernizer is an agent published in the GitHub repository rafaelkamimura/claude-tools (10 stars, last pushed 8mo ago), licensed MIT. It adds 48 tokens to every session and 242 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to code-refactoring-legacy-modernizer, differing in 7 lines, and is treated as a copy.