What is fettle-security-review?

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.

Use it to review Python, JavaScript, TypeScript, Go, or other supported code before asking whether the highest-severity findings should be fixed.

It helps find common security problems and organizes them by severity, with explanations and suggested fixes.

How MilindGaharwar/fettle configures Claude Code and OpenCode

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/.opencode/commands/fettle-security-review.md

Clone the repo

git clone --depth 1 https://github.com/MilindGaharwar/fettle

Made for: Claude Code, OpenCode.

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.

README.md

[![agentmods](https://agentmods.dev/badge/commands/milindgaharwar/fettle/fettle-security-review.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.svg" alt="Measured on agentmods" height="20"></a>

Per session 16 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 250 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.

Model	Per session	Once invoked
Fable 5.1	$0.00016	$0.00250
Opus 5	$0.00008	$0.00125
Sonnet 5	$0.00003	$0.00050
Haiku 4.5	$0.00002	$0.00025

Measured 7d ago against content hash 10723ed63d63, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, 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 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

Copies of this mod

1 near-identical copy found in the catalogue:

security-review — 88% identical, 9 lines differ

.opencode/commands/fettle-security-review.md · 37 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

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

Run the scanner:

python3 -m fettle.security_review --path TARGET

Present findings grouped by severity (CRITICAL/HIGH first).
For each finding, explain:
- What the vulnerability is
- How it could be exploited
- The recommended fix
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.

7d 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 (2 stars, last pushed 3d ago), licensed Apache-2.0. It adds 16 tokens to every session and 250 once invoked, about $0.0001 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 2026-08-31.

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fettle: Command for Claude Code