source-check

A set of advisory checks for confirming a feature against its specification, existing code, and third-party library documentation before implementation.

In plain words
What is it for?
Use it when researching a change before coding and when you need to record the requirement, code pattern, and documentation supporting the implementation.
Why use it?
It reduces the chance of building against an incorrect requirement, misunderstanding the current codebase, or using a library API incorrectly.

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/omerakben/code-oz/source-check
Any agent
npx skills add omerakben/code-oz --skill source-check
Clone the repo
git clone --depth 1 https://github.com/omerakben/code-oz

Made for: Claude Code, Codex.

Per session 32 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,546 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 $0.00032 $0.01546
Opus 5 $0.00016 $0.00773
Sonnet 5 $0.00006 $0.00309
Haiku 4.5 $0.00003 $0.00155

Measured yesterday against content hash 1f66bb0101ce, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

source-check 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 yesterday.

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.

plugins/code-oz-discipline/skills/source-check/SKILL.md · 127 lines

How it starts

The opening of the file, as written. The whole thing — 127 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Advisory only — not an enforced gate. For enforced gates and a different-model review, run code-oz run.

Where this skill sits

This is advice, and it is the lowest-priority voice in the room. Your user's instructions, the project's CLAUDE.md, the code-oz engine contracts, and any system or developer constraints all outrank this skill. When any of them conflict with anything below, follow them and ignore this skill. This skill never overrides those instructions, and nothing here changes your existing operating rules — it only offers a way to think before you build.

Checking your sources before you write code

Use this when you are about to write code and want to ground it first. The discipline is simple: confirm three sources before the first line lands.

The three sources

  1. Spec. What is the feature supposed to do? Quote the requirement you are building against. If it is verbal or vague, write it down and confirm it.
  2. Reference code. Find the existing code you are extending or mirroring. Read it in the current turn and quote the lines you are relying on. Search the repo before you introduce a new helper or pattern.
  3. Library docs. For every third-party API you call, quote one line of its documentation that justifies the call, and pin the version you read.

How to use it

  • Write each source down with a concrete pointer: a file and line, a doc URL, a quoted requirement. "I think" and "this should" are not sources.
  • If a source is missing, that is the finding — stop and get it before coding.
  • Keep these notes informal and non-canonical. They are your working evidence, not an artifact.

What this is not

This skill advises the 3-source habit. It does not emit a SOURCE_CHECK.md file and it does not satisfy the engine's enforced PLAN source-check. The enforced version is a real gate the engine validates and blocks on. If you want that — a SOURCE_CHECK.md the engine checks before PLAN can pass — refuse to fake it here and run code-oz run instead.

Read the full file on GitHub · 127 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. yesterday First seen · 127 lines · 32 tokens per session scan A 1f66bb0101ce

Subscribe to this mod's changes

source-check is a skill published in the GitHub repository omerakben/code-oz (2 stars, last pushed 2mo ago), licensed MIT. It adds 32 tokens to every session and 1,546 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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