verify-ref

verify-ref is a skill for Claude Code, Codex from hiendinhngoc/unknowns. It costs 60 tokens per session (675 once invoked), scanned A, original, MIT.

A review step for understanding existing code before copying, adapting, or porting it. Porting means moving behaviour from one implementation to another.

In plain words
What is it for?
It helps document data flow, guards, fallbacks, retries, ordering, invariants, hidden dependencies, and other behaviour before implementation begins.
Why use it?
It helps prevent writing a new version based on a mistaken reading of the reference code, and requires unresolved dependencies and edge cases to be identified first.

Skill for Claude CodeCodex

Written for Claude Code and Codex: shipped in a Claude Code plugin, but also agents/openai.yaml present.

Part of the unknowns plugin — 6 skills shipped together

Good fit It helps document data flow, guards, fallbacks, retries, ordering, invariants, hidden dependencies, and other behaviour before implementation begins.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/hiendinhngoc/unknowns/verify-ref
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 hiendinhngoc/unknowns --skill verify-ref
Clone the repo
git clone --depth 1 https://github.com/hiendinhngoc/unknowns

Made for: Claude Code, Codex.

Or install unknowns, the plugin that ships this one along with the rest of its 6 skills.

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 verify-ref

README.md
[![agentmods](https://agentmods.dev/badge/skills/hiendinhngoc/unknowns/verify-ref.svg)](https://agentmods.dev/skills/hiendinhngoc/unknowns/verify-ref)
Your own site
<a href="https://agentmods.dev/skills/hiendinhngoc/unknowns/verify-ref"><img src="https://agentmods.dev/badge/skills/hiendinhngoc/unknowns/verify-ref.svg" alt="Measured on agentmods" height="20"></a>
Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 675 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 $0.00060 $0.00675
Opus 5 $0.00030 $0.00338
Sonnet 5 $0.00012 $0.00135
Haiku 4.5 $0.00006 $0.00068

Measured 8d ago against content hash d4ccf593f91c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

verify-ref 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 8d 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/verify-ref/SKILL.md · 63 lines

How it starts

The opening of the file, as written. The whole thing — 63 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Reference Verification

Prove you understand the reference implementation BEFORE porting it. Misunderstood references produce confidently wrong ports.

Write no implementation code until the user confirms the comprehension proof below.

Process

  1. Locate the reference. Use the argument or conversation context. If ambiguous, ask which implementation is the reference — don't guess.

  2. Set a behavioral boundary, then read it fully. Read the referenced unit, its direct callers, and direct dependencies that affect observable behavior. Follow deeper calls only while they change outputs, side effects, errors, or ordering. List unresolved or external dependencies instead of recursively expanding without a stop condition.

  3. Produce the comprehension proof, covering:

    • Data flow: inputs → transformations → outputs, in order
    • Edge cases handled: every guard, fallback, retry, and special case, and what each protects against
    • Invariants: what must remain true before/after (ordering, uniqueness, idempotency, transactional boundaries)
    • Hidden dependencies: globals, config, environment, call-order assumptions, side effects the signature doesn't show. For UI code, also name the framework semantics the reference leans on: lifecycle hooks that fire once vs. per-render, view identity, and task/cleanup-on-teardown behavior — these are where ports break silently.

    Proportionality: for a small same-repo adaptation (roughly ≤30 lines, no concurrency, no money/auth/persistence), a short proof of just Data flow and What would break if I got this wrong? suffices — but step 2's full read of the reference and its callers is never skipped; that read is where latent bugs surface.

  4. Self-challenge. Add a section: "What would break if I got this wrong?" — name the 2-3 misreadings most likely to cause a subtly wrong port and say why your reading is correct (cite file:line evidence).

  5. Gate. Ask the user to confirm the proof or correct it. Only after confirmation may implementation begin. A plan the user already approved that names this exact port also counts as confirmation — say the proof is being accepted under that approval and proceed. Otherwise, if no interactive user is available, stop after the proof and identify the exact uncertainty that needs review; do not silently treat the proof as approval.

Read the full file on GitHub · 63 lines

Files

What ships with it

1 file 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. 8d ago First seen · 63 lines · 60 tokens per session scan A d4ccf593f91c

Subscribe to this mod's changes

verify-ref is a skill published in the GitHub repository hiendinhngoc/unknowns (9 stars, last pushed 1mo ago), licensed MIT. It adds 60 tokens to every session and 675 once invoked, about $0.0003 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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