fowler

A coding assistant for improving the internal structure of existing code without changing what it does. It follows Martin Fowler’s named refactoring techniques and can review, apply, or explain them.

In plain words
What is it for?
Use it to diagnose design problems, carry out a specific refactoring, or compare refactoring techniques. It can also teach these techniques with examples in the project’s programming language.
Why use it?
It helps identify code smells, which are patterns that often make code harder to change or understand. When applying changes, it breaks the work into small steps and runs tests between them.

Command

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 commands/el-feo/ai-context/fowler
Clone the repo
git clone --depth 1 https://github.com/el-feo/ai-context
Per session 33 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 202 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 $0.00033 $0.00202
Opus 5 $0.00016 $0.00101
Sonnet 5 $0.00007 $0.00040
Haiku 4.5 $0.00003 $0.00020

Measured 2d ago against content hash a28e184467ff, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fowler 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 2d 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/fowler/commands/fowler.md · 19 lines

What it actually says

Engage the fowler skill and follow its SKILL.md.

Auto-detect the mode from the request (or honor an explicit leading keyword):

  • diagnose — review the given code for Fowler's code smells and prescribe the catalog refactorings that cure them.
  • refactor — apply a refactoring (named by the user, or chosen from a diagnosis) following the catalog mechanics: small behavior-preserving steps, tests run between steps.
  • advise — answer design questions, compare techniques, or teach a smell or refactoring with examples in the user's language.

$ARGUMENTS

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. 2d ago First seen · 19 lines · 0 tokens per session scan A a28e184467ff

Subscribe to this mod's changes

fowler is a command published in the GitHub repository el-feo/ai-context (12 stars, last pushed 1mo ago), licensed MIT. It adds 33 tokens to every session and 202 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.