yds-data-validation

yds-data-validation is a skill for Claude Code, Codex from ymd38/dev-skills. It costs 158 tokens per session (4,146 once invoked), scanned A, original, MIT.

A read-only checker for a project’s test or seed data. It compares the data with what the code expects and reports counts, missing values, duplicates, invalid formats, broken references, distributions, and sample rows.

In plain words
What is it for?
Use it to inspect fixtures or seed data and create a factual validation report, either on its own or as an input to an issue-resolution workflow.
Why use it?
It finds data problems without changing the data, database structure, or code. Each problem includes the expected result, actual result, and supporting evidence.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/ymd38/dev-skills/yds-data-validation
Any agent
npx skills add ymd38/dev-skills --skill yds-data-validation
Clone the repo
git clone --depth 1 https://github.com/ymd38/dev-skills

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 yds-data-validation

README.md
[![agentmods](https://agentmods.dev/badge/skills/ymd38/dev-skills/yds-data-validation.svg)](https://agentmods.dev/skills/ymd38/dev-skills/yds-data-validation)
Your own site
<a href="https://agentmods.dev/skills/ymd38/dev-skills/yds-data-validation"><img src="https://agentmods.dev/badge/skills/ymd38/dev-skills/yds-data-validation.svg" alt="Measured on agentmods" height="20"></a>
Per session 158 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,146 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00158 $0.04146
Opus 5 $0.00079 $0.02073
Sonnet 5 $0.00032 $0.00829
Haiku 4.5 $0.00016 $0.00415

Measured 3d ago against content hash 6bd32e61b32b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

yds-data-validation 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 3d 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/yds-data-validation/SKILL.md · 355 lines

How it starts

The opening of the file, as written. The whole thing — 355 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Role: Data Validator (Read-Only)

You verify that a project's data is what the code assumes it is. Findings are grounded in concrete numbers and sampled rows, never in impressions. Every failed check states the expected value, the actual value, and the evidence that produced it.

This is a read-only inspection. You do not modify data, schema, or code. Remediation is the job of yds-gh-issue-resolver; this skill only produces the verdict it acts on.

Two Modes

Mode Invoked by File output
standalone the user (/yds-data-validation <path>) none by default — session output only. Save to docs/yds-data-validation/<target>.YYYYMMDD.md only when the user explicitly asks for a report file
verify yds-gh-issue-resolver Step 8 never — session output only

No JSON summary is produced in either mode. This skill is deliberately excluded from the yds-progress-dashboard data flow so that routine validation does not add commit targets.


Phase 1: Scope & Data Source Resolution

1.1 Resolve the data source — in this order, stop at the first hit

  1. The project's own test fixtures / seed data Look for, in order: testdata/, fixtures/, test/fixtures/, spec/fixtures/, seeds/, db/seeds/, factory definitions (factories/, *_factory.*), golden files (*.golden, *.snap), and fixture loaders referenced from the test setup.
  2. An explicitly configured connection A connection string that the project itself declares for a non-production target — e.g. DATABASE_URL in .env.test / .env.local, a docker-compose.yml service, or a test container definition. The value must be read from a file in the repository; do not accept one inferred from shell history, cloud credentials, or a running process.
  3. Neither exists → stop. Report SOURCE: unavailable and list exactly what is missing. Do not guess a connection, do not scan the network, and do not fall back to a production target.

Read the full file on GitHub · 355 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. 3d ago First seen · 355 lines · 158 tokens per session scan A 6bd32e61b32b

Subscribe to this mod's changes

yds-data-validation is a skill published in the GitHub repository ymd38/dev-skills (3 stars, last pushed 6d ago), licensed MIT. It adds 158 tokens to every session and 4,146 once invoked, about $0.0008 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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