verification-loop

verification-loop is a skill for Claude Code from mhylle/claude-skills-collection. It costs 67 tokens per session (4,441 once invoked), scanned A, original, MIT.

A six-part code verification process that checks the build, types, lint rules, tests, security issues, and final code changes.

In plain words
What is it for?
Use it after coding work to confirm that the project builds, type-checks, passes lint and tests, has no obvious security problems, and contains only intended changes.
Why use it?
It catches different kinds of defects before an implementation is considered complete, including compilation failures, regressions, unsafe patterns, and unintended edits.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: mentions subagents.

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is ./scripts/verify-diff.sh.

Part of the devflow plugin — 38 skills, 13 agents, 5 hooks shipped together

Good fit Use it after coding work to confirm that the project builds, type-checks, passes lint and tests, has no obvious security problems, and contains only intended changes.

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/mhylle/claude-skills-collection
agentmods
npx agentmods add skills/mhylle/claude-skills-collection/verification-loop

Made for: Claude Code.

Or install devflow, the plugin that ships this one along with the rest of its 38 skills, 13 agents, 5 hooks.

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 verification-loop

README.md
[![agentmods](https://agentmods.dev/badge/skills/mhylle/claude-skills-collection/verification-loop/github.svg)](https://agentmods.dev/skills/mhylle/claude-skills-collection/verification-loop)
Your own site
<a href="https://agentmods.dev/skills/mhylle/claude-skills-collection/verification-loop"><img src="https://agentmods.dev/badge/skills/mhylle/claude-skills-collection/verification-loop/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 verification-loop

Your own site · 80×15
<a href="https://agentmods.dev/skills/mhylle/claude-skills-collection/verification-loop"><img src="https://agentmods.dev/badge/skills/mhylle/claude-skills-collection/verification-loop.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,441 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 5 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Privilege Escalation · line 387
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • medium Tool Misuse · line 239
    Tool defaults are unsafe or overly permissive (e.g. disabled TLS verification, no authentication, world-writable permissions). Unsafe defaults widen the attack surface.
    Fix: Override unsafe defaults with secure settings (verify=True, auth required, restrictive permissions). Review and harden all tool configurations.
  • medium MCP Rug Pull · line 535
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 543
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • low Excessive Agency · line 506
    Skill's behavior or capabilities extend beyond its stated purpose. Scope creep allows an agent to perform actions unrelated to its documented functionality, increasing the attack surface.
    Fix: Limit the skill's scope to its documented purpose. Remove instructions that enable the agent to perform actions outside its stated functionality.
How audits are shown
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 $0.00067 $0.04441
Opus 5 $0.00034 $0.02220
Sonnet 5 $0.00013 $0.00888
Haiku 4.5 $0.00007 $0.00444

Measured 10d ago against content hash 13bf14fb3d49, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

verification-loop 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 10d 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/verification-loop/SKILL.md · 557 lines

How it starts

The opening of the file, as written. The whole thing — 557 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Verification Loop

A systematic 6-check verification framework that validates implementation quality across multiple dimensions: build, types, lint, tests, security, and diff review. Catches issues early, ensures code compiles, type-checks, passes linting, runs tests, has no security issues, and contains no unintended changes.

Terminology: this skill uses "Checks" (Check 1–6). Don't confuse with "Phases" (plan phases) or "Steps" (implement-phase steps).


Design philosophy

Defense in depth — each check catches a different category of issue:

Check Catches Why it matters
Build Syntax errors, missing deps, bundling issues Code must compile to run
Types Type mismatches, null safety, interface violations Type safety prevents runtime errors
Lint Style violations, code smells, potential bugs Consistent, maintainable code
Tests Logic errors, regressions, broken contracts Functional correctness
Security Secrets, debug code, vulnerable patterns Production safety
Diff Unintended changes, scope creep, leftover code Change discipline

Fail fast — checks are ordered by detection speed. Build errors appear in seconds; security scans take longer. Fast checks first provide rapid feedback on common issues.

Project-agnostic — detect project type automatically, apply the matching tooling. Node.js, Python, Go, Rust, and mixed-language projects all work.

Idempotent — running the loop multiple times produces the same result. Each check passes or fails deterministically based on codebase state.


When to use

Automatically invoked by implement-phase as Step 2 (Exit Condition Verification), before integration testing, after implementation subagents complete.

Manually invoked for:

  • Validating changes before committing
  • Checking code quality after refactoring
  • Pre-merge verification
  • Reproducing CI/CD failures locally

Don't use for:

  • Reading or analyzing code (no changes made)
  • Running exploratory tests (use the test runner directly)
  • Checking a single file (use individual tools)

Read the full file on GitHub · 557 lines

Files

What ships with it

4 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. 10d ago First seen · 557 lines · 67 tokens per session scan A 13bf14fb3d49

Subscribe to this mod's changes

verification-loop is a skill published in the GitHub repository mhylle/claude-skills-collection (18 stars, last pushed 7d ago), licensed MIT. It adds 67 tokens to every session and 4,441 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 2026-08-30.

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