detecting-skill-regression

detecting-skill-regression is a skill for Claude Code from Nolane-x/forge-os. It costs 40 tokens per session (178 once invoked), scanned A, original, MIT.

A skill for checking whether a change to a skill, policy, provider, model, or section makes agent results worse.

In plain words
What is it for?
Use it to compare a changed setup with an earlier tested baseline, find affected tests, and quarantine or roll back harmful changes.
Why use it?
It helps detect drops in completion, quality, safety, routing accuracy, or use of the available context before the change is kept.

Skill for Claude Code

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

Part of the forgeos plugin — 196 skills, 1 command, 1 agent, 1 MCP server shipped together

Good fit Use it to compare a changed setup with an earlier tested baseline, find affected tests, and quarantine or roll back harmful changes.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/nolane-x/forge-os/detecting-skill-regression
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 Nolane-x/forge-os --skill detecting-skill-regression
Clone the repo
git clone --depth 1 https://github.com/Nolane-x/forge-os

Made for: Claude Code.

Or install forgeos, the plugin that ships this one along with the rest of its 196 skills, 1 command, 1 agent, 1 MCP server.

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 detecting-skill-regression

README.md
[![agentmods](https://agentmods.dev/badge/skills/nolane-x/forge-os/detecting-skill-regression.svg)](https://agentmods.dev/skills/nolane-x/forge-os/detecting-skill-regression)
Your own site
<a href="https://agentmods.dev/skills/nolane-x/forge-os/detecting-skill-regression"><img src="https://agentmods.dev/badge/skills/nolane-x/forge-os/detecting-skill-regression.svg" alt="Measured on agentmods" height="20"></a>
Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 178 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 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 $0.00040 $0.00178
Opus 5 $0.00020 $0.00089
Sonnet 5 $0.00008 $0.00036
Haiku 4.5 $0.00004 $0.00018

Measured 7d ago against content hash b79eaec2501c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

detecting-skill-regression 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 7d 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-v2/kernel/detecting-skill-regression/SKILL.md · 23 lines

What it actually says

Detecting Skill Regression

Core principle

Resolve affected benchmark and transfer-test slices. Quarantine or roll back when confidence shows harmful change. The runtime owns deterministic scope, coverage, policy, and evidence checks; the agent owns only the judgment that cannot be reduced safely to code.

Do not activate when

  • no behavior-affecting content changed
  • the skill has no prior validated baseline
Files

What ships with it

9 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 7d ago First seen · 23 lines · 40 tokens per session scan A b79eaec2501c

Subscribe to this mod's changes

detecting-skill-regression is a skill published in the GitHub repository Nolane-x/forge-os (10 stars, last pushed 1mo ago), licensed MIT. It adds 40 tokens to every session and 178 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 2026-08-31.

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