build-the-gate-before-the-content

build-the-gate-before-the-content is a skill for Claude Code, Codex from brcampidelli/chimera-agent. It costs 35 tokens per session (598 once invoked), scanned A, original, Apache-2.0.

A development rule for adding automated checks before the content or code they protect exists. The check starts passing, then blocks new violations.

In plain words
What is it for?
Use it when introducing style rules, freshness checks, data-format checks, link validation, or spending limits in a new project.
Why use it?
Adding checks later can leave a large backlog and make them tempting to disable. Starting with the check keeps the rule active from the first change.

Skill for Claude CodeCodex

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

Good fit Use it when introducing style rules, freshness checks, data-format checks, link validation, or spending limits in a new project.

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Install with agentmods
npx agentmods add skills/brcampidelli/chimera-agent/build-the-gate-before-the-content
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 build-the-gate-before-the-content
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.

agentmods badge for build-the-gate-before-the-content

README.md
[![agentmods](https://agentmods.dev/badge/skills/brcampidelli/chimera-agent/build-the-gate-before-the-content/github.svg)](https://agentmods.dev/skills/brcampidelli/chimera-agent/build-the-gate-before-the-content)
Your own site
<a href="https://agentmods.dev/skills/brcampidelli/chimera-agent/build-the-gate-before-the-content"><img src="https://agentmods.dev/badge/skills/brcampidelli/chimera-agent/build-the-gate-before-the-content/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 build-the-gate-before-the-content

Your own site · 80×15
<a href="https://agentmods.dev/skills/brcampidelli/chimera-agent/build-the-gate-before-the-content"><img src="https://agentmods.dev/badge/skills/brcampidelli/chimera-agent/build-the-gate-before-the-content.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 35 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 598 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 $0.00035 $0.00598
Opus 5 $0.00017 $0.00299
Sonnet 5 $0.00007 $0.00120
Haiku 4.5 $0.00003 $0.00060

Measured 11d ago against content hash 58c3de3bf732, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

build-the-gate-before-the-content 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 11d 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/build-the-gate-before-the-content/SKILL.md · 62 lines

How it starts

The opening of the file, as written. The whole thing — 62 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Trigger

You are about to build something that will need a rule enforced across it — a style constraint, a freshness check, a schema, a link validator, a budget. The natural order is to build the thing and add the check once there is something to check.

It does not apply to a check you are adding to code that already exists; that is a different and harder job, and the answer there is a ratchet, not a wall.

Do

  1. Add the check in the first commit, before there is any content for it to fail on. It passes trivially, which is the point: it starts life green.
  2. Give it a failure message that says what to run. A gate whose output is assert False gets deleted by the next person who hits it at 2am.
  3. Write the check so it fails on the first violation, not the hundredth. Ratchets are for legacy; greenfield starts at zero.
  4. When the check does fire, fix the content. Every time you change the check instead, note in the commit message which case forced it.

Avoid

"We will turn this on once the pages are written." By then the check has a backlog, turning it on means a day of unrelated fixes, and the cheapest path is a skip list that never shrinks.

Avoid also loosening a gate in the same commit as the feature that tripped it. The loosening is invisible in a large diff, and it is the exact moment a gate stops being one — so it belongs in its own commit with its own explanation.

Check

Introduce a violation on purpose and confirm the build goes red — then remove it. Do this on the day you write the gate, not later.

A gate nobody has watched fail is not a gate; it is a file that claims to be one.

Risk

A gate written before the content encodes an assumption about content that does not exist yet, and some of those assumptions turn out wrong. Expect to narrow it once or twice early on.

That narrowing is the dangerous moment. Each one makes the rule weaker, and a rule narrowed three times without anybody noticing is a rule that no longer covers the case it was written for. Pin every narrowing with the failing example that caused it.

Read the full file on GitHub · 62 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. 11d ago First seen · 62 lines · 35 tokens per session scan A 58c3de3bf732

Subscribe to this mod's changes

build-the-gate-before-the-content is a skill published in the GitHub repository brcampidelli/chimera-agent (23 stars, last pushed today), licensed Apache-2.0. It adds 35 tokens to every session and 598 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.