refactoring-mikado-strangler

refactoring-mikado-strangler is a skill for Claude Code, Codex from DGouron/review-flow. It costs 48 tokens per session (1,471 once invoked), scanned A, original, MIT.

A guide for large software refactorings using the Mikado Method and the Strangler Fig approach. These methods help manage dependency-heavy changes, such as replacing a library, splitting a monolith, or migrating architecture.

In plain words
What is it for?
Use it to plan architecture migrations, module splits, library replacements, pattern changes, and other refactors that are larger than a normal test-driven development cycle.
Why use it?
It makes complex refactors easier to track and helps keep old functionality working during an incremental migration when that approach is chosen. The Mikado method records prerequisites before changes are made.

Skill for Claude CodeCodex

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/dgouron/review-flow/refactoring
Any agent
npx skills add DGouron/review-flow --skill refactoring
Clone the repo
git clone --depth 1 https://github.com/DGouron/review-flow

Made for: Claude Code, Codex.

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 refactoring-mikado-strangler

README.md
[![agentmods](https://agentmods.dev/badge/skills/dgouron/review-flow/refactoring.svg)](https://agentmods.dev/skills/dgouron/review-flow/refactoring)
Your own site
<a href="https://agentmods.dev/skills/dgouron/review-flow/refactoring"><img src="https://agentmods.dev/badge/skills/dgouron/review-flow/refactoring.svg" alt="Measured on agentmods" height="20"></a>
Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,471 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 $0.00048 $0.01471
Opus 5 $0.00024 $0.00736
Sonnet 5 $0.00010 $0.00294
Haiku 4.5 $0.00005 $0.00147

Measured 5d ago against content hash 8952d1482852, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

refactoring-mikado-strangler 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 5d 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.

.claude/skills/refactoring/SKILL.md · 295 lines

How it starts

The opening of the file, as written. The whole thing — 295 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Large Scale Refactoring - Mikado & Strangler Fig

Persona

Read .claude/roles/senior-dev.md — adopt this profile and follow all its rules.

Activation

This skill activates for refactorings that exceed a TDD cycle scope:

  • Architecture migration
  • Library or framework replacement
  • Splitting a monolithic module
  • Pattern change (e.g., callbacks -> promises -> async/await)
  • Bounded context restructuring

Choosing the method

Criterion Mikado Strangler Fig
Old code stays functional during No Yes
Need to deliver incrementally Difficult Ideal
Complex dependencies to untangle Ideal Possible
Complete replacement of a system Possible Ideal

Ask the user which method to use if it's not obvious.


Mikado Method

Principle

  1. Try the final goal directly
  2. Observe what breaks
  3. Revert immediately (no broken code left around)
  4. Note the discovered prerequisites in the graph
  5. Recurse on each prerequisite
  6. Implement the leaves of the graph (those with no dependencies)

Interactive workflow

Step 1: Initialization
MIKADO - Initialization

Main goal: [description]
Graph file: docs/mikado/[name]-graph.md

I will create the tracking file.
Shall we begin?

Create the graph file:

# Mikado Graph: [Goal]

## Status: IN PROGRESS

## Main goal
- [ ] [Goal description]

## Discovered prerequisites
(Fills in as attempts are made)

## Attempt history
(Log of attempts and discoveries)
Step 2: Attempt
MIKADO - Attempt

I will try: [goal or prerequisite]
Expected: [what should break]

Shall we try?

After validation:

  1. Attempt the modification
  2. Run yarn test:run
  3. Note EVERYTHING that breaks
  4. REVERT IMMEDIATELY with git checkout .
Step 3: Analysis
MIKADO - Analysis

Attempt: [what we tried]
Result: [success / failure]

Errors encountered:
- [error 1] -> Prerequisite: [required action]
- [error 2] -> Prerequisite: [required action]

I'm updating the graph.
Which prerequisite do we tackle first?

Read the full file on GitHub · 295 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. 5d ago First seen · 295 lines · 48 tokens per session scan A 8952d1482852

Subscribe to this mod's changes

refactoring-mikado-strangler is a skill published in the GitHub repository DGouron/review-flow (42 stars, last pushed 2d ago), licensed MIT. It adds 48 tokens to every session and 1,471 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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