openusage: Skill for Codex

.codex/skills/design-feature/SKILL.md

design-feature is a skill for Codex from janekbaraniewski/openusage. It costs 18 tokens per session (72 once invoked), scanned A, original, MIT.

A feature-design workflow that asks requirements questions, examines the codebase, and produces a design document with tasks.

In plain words
What is it for?
Use it to plan a new capability, explore the relevant source code, document the design, and outline the implementation work.
Why use it?
It gives feature planning a defined sequence so important requirements and affected code are considered before implementation.

Skill for Codex

Written for Codex: installed under .codex/.

This is janekbaraniewski/openusage's own configuration. It tells Codex how to work on openusage 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 openusage configures →

Reuse

Borrowing it

Nothing to install: this file belongs to janekbaraniewski/openusage. 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/janekbaraniewski/openusage/main/.codex/skills/design-feature/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/janekbaraniewski/openusage

Made for: 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 design-feature

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/janekbaraniewski/openusage/design-feature"><img src="https://agentmods.dev/badge/skills/janekbaraniewski/openusage/design-feature.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 72 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 warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Agent Snooping · line 10
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
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 $0.00018 $0.00072
Opus 5.5 $0.00007 $0.00029
Sonnet 5.5 $0.00004 $0.00014
Haiku 4.5 $0.00002 $0.00007

Measured 1mo ago against content hash d03d8ad47026, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

design-feature 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.

.codex/skills/design-feature/SKILL.md · 11 lines

What it actually says

Skill: Design Feature

Invocation: Design a feature: quiz, explore codebase, write design doc with tasks

Read and follow the full skill specification in docs/skills/design-feature/SKILL.md.

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 First seen · 11 lines · 18 tokens per session scan A d03d8ad47026

Subscribe to this mod's changes

design-feature is a skill published in the GitHub repository janekbaraniewski/openusage (235 stars, last pushed yesterday), licensed MIT. It adds 18 tokens to every session and 72 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 2026-08-30.

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