fettle: Command for Claude Code

.github/prompts/fettle-security-review.prompt.md

fettle-security-review is a command for Claude Code, GitHub Copilot from MilindGaharwar/fettle. It costs 21 tokens per session (265 once invoked), scanned A, original, Apache-2.0.

A slash command that runs static security checks on a selected path using Ruff security rules and Semgrep's OWASP patterns. Static checks inspect code without running the application.

In plain words
What is it for?
Use it to review Python, JavaScript, TypeScript, Go, or other supported code before asking whether the highest-severity findings should be fixed.
Why use it?
It helps find common security problems and organizes them by severity, with explanations and suggested fixes.

Command for Claude CodeGitHub Copilot

Written for Claude Code and GitHub Copilot: argument-hint in frontmatter, but also a Copilot chat mode or prompt.

This is MilindGaharwar/fettle's own configuration. It tells Claude Code and GitHub Copilot how to work on fettle itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything fettle configures →

Part of the fettle plugin — 34 commands, 4 hooks shipped together

Reuse

Borrowing it

Nothing to install: this file belongs to MilindGaharwar/fettle. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/MilindGaharwar/fettle/main/.github/prompts/fettle-security-review.prompt.md
Clone the repo
git clone --depth 1 https://github.com/MilindGaharwar/fettle

Made for: Claude Code, GitHub Copilot.

Or install fettle, the plugin that ships this one along with the rest of its 34 commands, 4 hooks.

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 fettle-security-review

README.md
[![agentmods](https://agentmods.dev/badge/commands/milindgaharwar/fettle/fettle-security-review/github.svg)](https://agentmods.dev/commands/milindgaharwar/fettle/fettle-security-review)
Your own site
<a href="https://agentmods.dev/commands/milindgaharwar/fettle/fettle-security-review"><img src="https://agentmods.dev/badge/commands/milindgaharwar/fettle/fettle-security-review/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for fettle-security-review

Your own site · 80×15
<a href="https://agentmods.dev/commands/milindgaharwar/fettle/fettle-security-review"><img src="https://agentmods.dev/badge/commands/milindgaharwar/fettle/fettle-security-review.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 21 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 265 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 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 $0.00021 $0.00265
Opus 5.5 $0.00008 $0.00106
Sonnet 5.5 $0.00004 $0.00053
Haiku 4.5 $0.00002 $0.00026

Measured 1mo ago against content hash a42c45c65cce, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

fettle-security-review 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 1mo 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

Copies of this mod

1 near-identical copy found in the catalogue:

.github/prompts/fettle-security-review.prompt.md · 39 lines

What it actually says

$ARGUMENTS refers to any text the user typed after the slash command.

Run a security review on the target path.

Procedure

  1. Determine target. Use $ARGUMENTS if provided, otherwise the current working directory.

  2. Run the scanner:

    python3 -m fettle.security_review --path TARGET
    
  3. Present findings grouped by severity (CRITICAL/HIGH first).

  4. For each finding, explain:

    • What the vulnerability is
    • How it could be exploited
    • The recommended fix
  5. Offer to fix the highest-severity findings automatically.

Scope

  • Python: ruff S-rules (full) + semgrep OWASP
  • TypeScript/JavaScript/Go: semgrep OWASP only
  • Other languages: limited to semgrep generic rules

This is NOT a comprehensive security audit. It runs available static analysis tools. For production security assessments, complement with manual review and dedicated SAST tools.

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. 1mo ago Changed · +2 lines · +5 tokens per session a42c45c65cce
  2. 1mo ago First seen · 37 lines · 16 tokens per session scan A 10723ed63d63

Subscribe to this mod's changes

fettle-security-review is a command published in the GitHub repository MilindGaharwar/fettle (4 stars, last pushed today), licensed Apache-2.0. It adds 21 tokens to every session and 265 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-08-31.