modernize-transform

modernize-transform is a skill for Claude Code from MinhThang1009/dotclaude. It costs 47 tokens per session (734 once invoked), scanned A, original, MIT.

A guided process for rewriting one legacy module in a newer technology stack while checking that its behaviour stays the same. A module is a self-contained part of a software system.

In plain words
What is it for?
Use it to plan and transform a single module, identify its source and target structure, encode existing input-and-output behaviour, and verify the rewritten version.
Why use it?
It reduces the risk of changing business behaviour during modernization by creating characterization tests before the rewrite. These tests record what the old code actually does.

Skill for Claude Code

Written for Claude Code: argument-hint in frontmatter. Also seen: mentions subagents; positional $N argument.

Part of the code-modernization plugin — 7 skills, 5 agents shipped together

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 skills/minhthang1009/dotclaude/modernize-transform
Any agent
npx skills add MinhThang1009/dotclaude --skill modernize-transform
Clone the repo
git clone --depth 1 https://github.com/MinhThang1009/dotclaude

Made for: Claude Code.

Or install code-modernization, the plugin that ships this one along with the rest of its 7 skills, 5 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 modernize-transform

README.md
[![agentmods](https://agentmods.dev/badge/skills/minhthang1009/dotclaude/modernize-transform.svg)](https://agentmods.dev/skills/minhthang1009/dotclaude/modernize-transform)
Your own site
<a href="https://agentmods.dev/skills/minhthang1009/dotclaude/modernize-transform"><img src="https://agentmods.dev/badge/skills/minhthang1009/dotclaude/modernize-transform.svg" alt="Measured on agentmods" height="20"></a>
Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 734 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found 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 $0.00047 $0.00734
Opus 5 $0.00023 $0.00367
Sonnet 5 $0.00009 $0.00147
Haiku 4.5 $0.00005 $0.00073

Measured 6d ago against content hash 3e12cb774bbd, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

modernize-transform 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 6d 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.

plugins/code-modernization/skills/modernize-transform/SKILL.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Transform legacy/$1 module $2 into $3, with proof of behavioral equivalence.

This is a surgical, single-module transformation — one vertical slice of the strangler fig. Output goes to modernized/$1/$2/.

Step 0 — Plan (HITL gate)

Read the source module and any business rules in analysis/$1/BUSINESS_RULES.md that reference it. Then enter plan mode and present:

  • Which source files are in scope
  • The target module structure (packages/classes/files you'll create)
  • Which business rules / behaviors this module implements
  • How you'll prove equivalence (test strategy)
  • Anything ambiguous that needs a human decision NOW

Wait for approval before writing any code.

Step 1 — Characterization tests FIRST

Before writing target code, spawn the test-engineer subagent:

"Write characterization tests for legacy/$1 module $2. Read the source, identify every observable behavior, and encode each as a test case with concrete input → expected output pairs derived from the legacy logic. Target framework: <appropriate for $3>. Write to modernized/$1/$2/src/test/. These tests define 'done' — the new code must pass all of them."

Show the user the test file. Get a 👍 before proceeding.

Step 2 — Idiomatic transformation

Write the target implementation in modernized/$1/$2/src/main/.

Critical: Write code a senior $3 engineer would write from the specification, not from the legacy structure. Do NOT mirror COBOL paragraphs as methods, do NOT preserve legacy variable names like WS-TEMP-AMT-X. Use the target language's idioms: records/dataclasses, streams, dependency injection, proper error types, etc.

Include: domain model, service logic, API surface (REST controller or equivalent), and configuration. Add concise Javadoc/docstrings linking each class back to the rule IDs it implements.

Step 3 — Prove it

Run the characterization tests:

cd modernized/$1/$2 && <appropriate test command for $3>

Show the output. If anything fails, fix and re-run until green.

Read the full file on GitHub · 80 lines

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. 6d ago First seen · 80 lines · 47 tokens per session scan A 3e12cb774bbd

Subscribe to this mod's changes

modernize-transform is a skill published in the GitHub repository MinhThang1009/dotclaude (20 stars, last pushed 1mo ago), licensed MIT. It adds 47 tokens to every session and 734 once invoked, about $0.0002 per session on Opus 5. 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.

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