seo-regression-validator

seo-regression-validator is a skill for Codex from sergekostenchuk/seo-llm-skill-cluster. It costs 100 tokens per session (711 once invoked), scanned A, original, MIT.

A checker for search-engine and AI-readable website details, such as page titles, canonical URLs, structured data, sitemaps, and related files. It tests live pages, local HTML files, and generated website files.

In plain words
What is it for?
Use it to audit pages and public files, run negative tests for missing metadata, and produce a dated SEO validation report.
Why use it?
It shows whether these details are present and correct before someone claims the site is ready, and separates failures from warnings and checks that were not run.

Skill for Codex

Written for Codex: agents/openai.yaml present. Also seen: mentions Codex.

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is python3 <codex-skills-dir>/senior-skill-architect/scripts/lint_production_skill.py ./skills/seo-regression-validator.

Good fit Use it to audit pages and public files, run negative tests for missing metadata, and produce a dated SEO validation report.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/sergekostenchuk/seo-llm-skill-cluster
agentmods
npx agentmods add skills/sergekostenchuk/seo-llm-skill-cluster/seo-regression-validator

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 seo-regression-validator

README.md
[![agentmods](https://agentmods.dev/badge/skills/sergekostenchuk/seo-llm-skill-cluster/seo-regression-validator/github.svg)](https://agentmods.dev/skills/sergekostenchuk/seo-llm-skill-cluster/seo-regression-validator)
Your own site
<a href="https://agentmods.dev/skills/sergekostenchuk/seo-llm-skill-cluster/seo-regression-validator"><img src="https://agentmods.dev/badge/skills/sergekostenchuk/seo-llm-skill-cluster/seo-regression-validator/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 seo-regression-validator

Your own site · 80×15
<a href="https://agentmods.dev/skills/sergekostenchuk/seo-llm-skill-cluster/seo-regression-validator"><img src="https://agentmods.dev/badge/skills/sergekostenchuk/seo-llm-skill-cluster/seo-regression-validator.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 100 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 711 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 $0.00100 $0.00711
Opus 5 $0.00050 $0.00356
Sonnet 5 $0.00020 $0.00142
Haiku 4.5 $0.00010 $0.00071

Measured 11d ago against content hash ce256bb92b66, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

seo-regression-validator 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.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/audit_static_seo.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/seo-regression-validator/SKILL.md · 92 lines

How it starts

The opening of the file, as written. The whole thing — 92 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SEO Regression Validator

Use this skill after technical SEO/schema guidance exists, before claiming a site or skill output is done.

Read references/regression-checklist.md before running a broad audit.

Owns

  • live HTML and local fixture checks;
  • pass/fail severity model;
  • timestamped evidence reports;
  • schema/head metadata checks;
  • public artifact reachability checks;
  • regression report templates;
  • negative tests for missing JSON-LD, duplicate canonical, missing image, and fake reports.

Does Not Own

  • implementing SEO fixes;
  • Search Console credentialed data;
  • analytics exports;
  • external authority placement;
  • mutating target websites.

Workflow

  1. Define target URLs or fixture files.
  2. Record timestamp, target, method, and user agent.
  3. Fetch or read the target without mutation.
  4. Run deterministic checks using scripts/audit_static_seo.py when HTML is available.
  5. Separate critical failures, warnings, and skipped checks.
  6. Record skipped checks instead of treating them as passes.
  7. Produce or update seo-regression-report.json and a human-readable validation summary.
  8. Route implementation fixes to the appropriate specialist.

Critical By Default

  • missing <title>;
  • missing meta description;
  • missing or duplicate canonical;
  • no JSON-LD on pages expected to have schema;
  • invalid JSON-LD;
  • NewsArticle without usable image;
  • public page blocked or unreachable during live check;
  • report claims success without fetching or reading target.

Warning By Default

  • missing hreflang when a multilingual equivalent is expected;
  • missing OG/Twitter social tags;
  • missing RSS autodiscovery;
  • missing viewport;
  • article meta tags missing when an article schema exists;
  • no visible breadcrumb when BreadcrumbList is expected;
  • performance metrics not measured.

Safety And Privacy Boundaries

  • Do not mutate target sites.
  • Do not use credentials unless the user explicitly provides them for this task.
  • Do not store cookies, tokens, raw private analytics, raw IP logs, or private Search Console rows in reports.
  • Do not claim ranking, indexing, citation, or crawler behavior from one HTML check.

Read the full file on GitHub · 92 lines

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. 11d ago First seen · 92 lines · 100 tokens per session scan A ce256bb92b66

Subscribe to this mod's changes

seo-regression-validator is a skill published in the GitHub repository sergekostenchuk/seo-llm-skill-cluster (39 stars, last pushed 3mo ago), licensed MIT. It adds 100 tokens to every session and 711 once invoked, about $0.0005 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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