pin-the-case-that-narrowed-the-rule

pin-the-case-that-narrowed-the-rule is a skill for Claude Code, Codex from brcampidelli/chimera-agent. It costs 44 tokens per session (567 once invoked), scanned A, original, Apache-2.0.

A testing rule for preserving a legitimate case when narrowing a check after it reports a false positive.

In plain words
What is it for?
Use it when adding an allowlist, exemption, or narrower pattern to a checker. It helps document why the flagged case is safe and verify that similar violations still fail.
Why use it?
Without a regression test, an exemption can gradually weaken the rule until it stops catching real problems. Testing both the valid case and a real violation keeps the distinction clear.

Skill for Claude CodeCodex

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

Good fit Use it when adding an allowlist, exemption, or narrower pattern to a checker. It helps document why the flagged case is safe and verify that similar violations still fail.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/brcampidelli/chimera-agent/pin-the-case-that-narrowed-the-rule
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 brcampidelli/chimera-agent --skill pin-the-case-that-narrowed-the-rule
Clone the repo
git clone --depth 1 https://github.com/brcampidelli/chimera-agent

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.

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README.md
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Your own site
<a href="https://agentmods.dev/skills/brcampidelli/chimera-agent/pin-the-case-that-narrowed-the-rule"><img src="https://agentmods.dev/badge/skills/brcampidelli/chimera-agent/pin-the-case-that-narrowed-the-rule/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.

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Your own site · 80×15
<a href="https://agentmods.dev/skills/brcampidelli/chimera-agent/pin-the-case-that-narrowed-the-rule"><img src="https://agentmods.dev/badge/skills/brcampidelli/chimera-agent/pin-the-case-that-narrowed-the-rule.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 567 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 $0.00044 $0.00567
Opus 5 $0.00022 $0.00283
Sonnet 5 $0.00009 $0.00113
Haiku 4.5 $0.00004 $0.00057

Measured 12d ago against content hash 9ae6da37eebf, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

pin-the-case-that-narrowed-the-rule 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/pin-the-case-that-narrowed-the-rule/SKILL.md · 61 lines

What it actually says

Trigger

A check you wrote has failed on something that is actually fine, and you are about to add an exemption, an allowlist entry, or a narrower pattern.

It does not apply when the check found a real problem — fix the problem. It also does not apply to tuning a threshold before the check has ever run in anger.

Do

  1. Write down, in one sentence, why the flagged case is legitimate. If you cannot, the check may be right and the code wrong.
  2. Add both cases to the test suite: the legitimate one that must pass, and a synthetic version of the real violation that must still fail.
  3. Narrow the rule as little as possible. Exempt a path, not a whole directory; require a negation nearby, rather than deleting the phrase from the list.
  4. Put the narrowing in its own commit, and say in the message which case forced it.

Avoid

Deleting the rule because it was annoying once. Also avoid the quieter version: broadening an exemption until the rule covers nothing — an allowlist that grows every sprint is a rule being retired one line at a time, without anyone deciding to retire it.

Avoid exempting by file when the real distinction is by meaning. A phrase check that bans a sentence outright will ban the warning that negates it, and the honest fix is to require the negation, not to stop checking that page.

Check

After narrowing, run the suite with the original violation reintroduced. It must still fail.

Then read the diff of the rule itself and ask: what class of problem can now get through that could not before? If you cannot answer, the narrowing was not understood.

Risk

This adds a test for every exception, and a suite full of exception tests is a suite that is tedious to read.

The bigger risk is treating the pinned test as proof the rule is still strong. It proves one case still fails. A rule narrowed five times has five pinned cases and possibly a large hole between them, and only re-reading the rule as a whole will show that.

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 · 61 lines · 44 tokens per session scan A 9ae6da37eebf

Subscribe to this mod's changes

pin-the-case-that-narrowed-the-rule is a skill published in the GitHub repository brcampidelli/chimera-agent (25 stars, last pushed today), licensed Apache-2.0. It adds 44 tokens to every session and 567 once invoked, about $0.0002 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.