verify-impl

verify-impl is a skill for Claude Code, Codex from sergeyklay/.agents. It costs 157 tokens per session (2,422 once invoked), scanned A, original, Apache-2.0.

A forensic comparison of a software implementation against its authoritative technical specification.

In plain words
What is it for?
Checking whether code matches a specification across requirements, constraints, interfaces, algorithms, design decisions, and invariants.
Why use it?
It finds missing requirements, changed behaviour, weakened rules, and other differences between what was specified and what was built.

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/sergeyklay/.agents/verify-impl
Any agent
npx skills add sergeyklay/.agents --skill verify-impl
Clone the repo
git clone --depth 1 https://github.com/sergeyklay/.agents

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 verify-impl

README.md
[![agentmods](https://agentmods.dev/badge/skills/sergeyklay/.agents/verify-impl.svg)](https://agentmods.dev/skills/sergeyklay/.agents/verify-impl)
Your own site
<a href="https://agentmods.dev/skills/sergeyklay/.agents/verify-impl"><img src="https://agentmods.dev/badge/skills/sergeyklay/.agents/verify-impl.svg" alt="Measured on agentmods" height="20"></a>
Per session 157 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,422 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 5.1 $0.00157 $0.02422
Opus 5 $0.00078 $0.01211
Sonnet 5 $0.00031 $0.00484
Haiku 4.5 $0.00016 $0.00242

Measured yesterday against content hash 5226632afdf3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

verify-impl 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.

.agents/skills/verify-impl/SKILL.md · 167 lines

How it starts

The opening of the file, as written. The whole thing — 167 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spec-vs-Implementation Verification

You are conducting a forensic verification - a systematic, evidence-based comparison of implemented code against its authoritative technical specification. You answer one question: does the implementation faithfully realize every requirement, constraint, design decision, interface contract, algorithm, and invariant defined in the specification?

The specification is the product of deliberate architectural work. Every footnote, every constraint, every edge-case note exists because an architect determined it was necessary. A missed requirement is a latent defect; a diverged algorithm is a behavioral bug; a weakened invariant is a potential security boundary violation.

Input

The user provides a path to a specification file (markdown). Read the spec in its entirety before classifying anything. The spec is the authoritative source of truth: if the code does not meet it, that is a failure of the implementation, not of the spec.

Workflow

The verification proceeds in seven phases. Each phase has a documented gate that prevents a specific failure mode (false positives, recency bias, severity inflation, missed cross-cutting concerns). Do not skip, merge, or abbreviate any phase.

Copy this checklist into your response and mark items as you complete them:

  • Phase 1 - Build project context
  • Phase 2 - Extract every verifiable requirement
  • Phase 3 - Discover the implementation surface
  • Phase 4 - Verify each requirement
  • Phase 5 - Cross-cutting verification
  • Phase 6 - Self-verification
  • Phase 7 - Verdict and remediation

Phase 1 - Build project context

Before verifying anything, understand the system the spec lives within.

Project documentation. Search and read:

  • Context files: CLAUDE.md, AGENTS.md, GEMINI.md, CURSOR.md
  • Project docs: README.md, CONTRIBUTING.md, ARCHITECTURE.md, plus docs/ or doc/ directories - especially design and ADR sets
  • Build manifests: package.json, go.mod, Cargo.toml, pyproject.toml, etc. - to understand the tech stack
  • Runtime model: .env.example, docker-compose.yml, compose.yml, Makefile

Read the full file on GitHub · 167 lines

Files

What ships with it

5 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. yesterday Changed · -6 tokens per session 5226632afdf3
  2. 5d ago First seen · 167 lines · 163 tokens per session scan A e23cc7c37b35

Subscribe to this mod's changes

verify-impl is a skill published in the GitHub repository sergeyklay/.agents (5 stars, last pushed today), licensed Apache-2.0. It adds 157 tokens to every session and 2,422 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.