derive-the-flag-dont-store-and-correct-it

derive-the-flag-dont-store-and-correct-it is a skill for Claude Code from maxrave-dev/kotlin-footguns. It costs 125 tokens per session (1,507 once invoked), scanned A, original, GPL-3.0.

A code-review rule about not storing a boolean separately when it can be calculated from state already being collected. The available description is incomplete.

In plain words
What is it for?
Use it when reviewing state handling, especially code using mutableStateOf, rememberSaveable, and LaunchedEffect. More specific use cases cannot be confirmed from the available description.
Why use it?
It points out a risk where saved state starts with a guessed value and is corrected only after the first screen render. The available information does not describe the complete rule or its scope.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the kotlin-footguns plugin — 148 skills shipped together

Good fit Use it when reviewing state handling, especially code using mutableStateOf, rememberSaveable, and LaunchedEffect. More specific use cases cannot be confirmed from the available description.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/maxrave-dev/kotlin-footguns/derive-the-flag-dont-store-and-correct-it
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 maxrave-dev/kotlin-footguns --skill derive-the-flag-dont-store-and-correct-it
Clone the repo
git clone --depth 1 https://github.com/maxrave-dev/kotlin-footguns

Made for: Claude Code.

Or install kotlin-footguns, the plugin that ships this one along with the rest of its 148 skills.

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 derive-the-flag-dont-store-and-correct-it

README.md
[![agentmods](https://agentmods.dev/badge/skills/maxrave-dev/kotlin-footguns/derive-the-flag-dont-store-and-correct-it/github.svg)](https://agentmods.dev/skills/maxrave-dev/kotlin-footguns/derive-the-flag-dont-store-and-correct-it)
Your own site
<a href="https://agentmods.dev/skills/maxrave-dev/kotlin-footguns/derive-the-flag-dont-store-and-correct-it"><img src="https://agentmods.dev/badge/skills/maxrave-dev/kotlin-footguns/derive-the-flag-dont-store-and-correct-it/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 derive-the-flag-dont-store-and-correct-it

Your own site · 80×15
<a href="https://agentmods.dev/skills/maxrave-dev/kotlin-footguns/derive-the-flag-dont-store-and-correct-it"><img src="https://agentmods.dev/badge/skills/maxrave-dev/kotlin-footguns/derive-the-flag-dont-store-and-correct-it.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 125 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,507 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 unknown 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 $0.00125 $0.01507
Opus 5 $0.00063 $0.00754
Sonnet 5 $0.00025 $0.00301
Haiku 4.5 $0.00013 $0.00151

Measured 12d ago against content hash bd58f5cfbb27, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

derive-the-flag-dont-store-and-correct-it 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 12d 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/derive-the-flag-dont-store-and-correct-it/SKILL.md · 97 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

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. 12d ago First seen · 97 lines · 125 tokens per session scan A bd58f5cfbb27

Subscribe to this mod's changes

derive-the-flag-dont-store-and-correct-it is a skill published in the GitHub repository maxrave-dev/kotlin-footguns (276 stars, last pushed 14d ago), licensed GPL-3.0. It adds 125 tokens to every session and 1,507 once invoked, about $0.0006 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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