fsl-design-review

fsl-design-review is a skill for Claude Code, Codex from ymm-oss/fsl. It costs 155 tokens per session (2,643 once invoked), scanned A, original, Apache-2.0.

A procedure for comparing or reviewing software designs against a stable requirements contract using FSL. It uses verification results and design principles such as SOLID to explain whether a proposed change still fits the contract.

In plain words
What is it for?
Reviewing design proposals, comparing alternatives, checking extensions, and assessing whether design changes preserve requirements.
Why use it?
It replaces vague design debates with concrete checks and counterexamples. This helps reveal when a new variant, extension, or change breaks an agreed behavior.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Reviewing design proposals, comparing alternatives, checking extensions, and assessing whether design changes preserve requirements.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ymm-oss/fsl/fsl-design-review
View source ↗ ymm-oss/fsl
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.

Any agent
npx skills add ymm-oss/fsl --skill fsl-design-review
Clone the repo
git clone --depth 1 https://github.com/ymm-oss/fsl

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 fsl-design-review

README.md
[![agentmods](https://agentmods.dev/badge/skills/ymm-oss/fsl/fsl-design-review/github.svg)](https://agentmods.dev/skills/ymm-oss/fsl/fsl-design-review)
Your own site
<a href="https://agentmods.dev/skills/ymm-oss/fsl/fsl-design-review"><img src="https://agentmods.dev/badge/skills/ymm-oss/fsl/fsl-design-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 fsl-design-review

Your own site · 80×15
<a href="https://agentmods.dev/skills/ymm-oss/fsl/fsl-design-review"><img src="https://agentmods.dev/badge/skills/ymm-oss/fsl/fsl-design-review.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 155 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,643 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00155 $0.02643
Opus 5 $0.00077 $0.01321
Sonnet 5 $0.00031 $0.00529
Haiku 4.5 $0.00015 $0.00264

Measured 9d ago against content hash 0fb7624bfa61, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

fsl-design-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 9d 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.

skills/fsl-design-review/SKILL.md · 176 lines

How it starts

The opening of the file, as written. The whole thing — 176 lines — stays where its author put it; the contents beside it link to each section on GitHub.

FSL Design Exploration — A Procedure for Translating Design Decisions into Contract-Conformance Checks

The core is the following 5-step procedure. Design principles (SOLID etc.) are not the starting point of the procedure; they appear as judgment lenses at each step. This skill's job is to translate "is this design good?" into "does this design conform to the frozen contract?" and have fslc answer with counterexamples.

Prerequisite: FSL syntax, verification commands, and repair protocol follow the fsl skill and its topic-specific references. This skill supplies only the procedure and the interpretation of results. If the user needs a new design-layer .fsl written before review, use fsl-design for authoring and return here for review/proposal judgment. Working examples: specs/bank.fsl + bank_impl.fsl + bank_refines.fsl (refinement), seat_booking_* (state-tag-dependent mappings), specs/bank_system.fsl (compose).

Procedure

Step 1 — Translate the design question into the language of contracts

Design questions almost always fall into one of four shapes: comparing new design proposals / adding a variant or extension / reviewing a change to an existing design / judging substitutability. In every shape, what you identify is the same:

  • The open part: what may change (variants, extension points, the changed site)
  • The closed part = the contract: what must not break (invariants, guards, externally observable state)

Lens — OCP: decide the "range you close" here. DIP: what abstraction should the design proposals all depend on in common. Align with the user on the candidate contracts as a bullet list before proceeding (do not create a deliverable file; chat is fine).

Do not infer the open/closed boundary, extension points, substitutability contract, variant roster, or action correspondence from general design taste. If the source material does not say what must remain stable or how a detail action maps to an abstract action, ask. A refinement proof is only meaningful for the contract the human agreed to freeze.

Read the full file on GitHub · 176 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. 9d ago First seen · 176 lines · 155 tokens per session scan A 0fb7624bfa61

Subscribe to this mod's changes

fsl-design-review is a skill published in the GitHub repository ymm-oss/fsl (23 stars, last pushed yesterday), licensed Apache-2.0. It adds 155 tokens to every session and 2,643 once invoked, about $0.0008 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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