check-coverage

check-coverage is a skill for Claude Code, Codex from sd0xdev/sd0x-harness. It costs 27 tokens per session (603 once invoked), scanned A, original, MIT.

A review of whether a feature is tested at three levels: unit tests for individual pieces, integration tests for connected components, and end-to-end tests for complete user flows.

In plain words
What is it for?
Use it to read feature documentation, inventory related source code, map unit, integration, and end-to-end tests, identify missing coverage, and recommend tests for important gaps.
Why use it?
It reveals untested source files, missing boundary cases, and gaps between isolated tests and real application behavior. The result is an actionable assessment rather than a request to generate or run tests.

Skill for Claude CodeCodex

Part of the sd0x-dev-flow plugin — 40 skills, 16 agents, 5 hooks shipped together

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/sd0xdev/sd0x-harness/check-coverage
Any agent
npx skills add sd0xdev/sd0x-harness --skill check-coverage
Clone the repo
git clone --depth 1 https://github.com/sd0xdev/sd0x-harness

Made for: Claude Code, Codex.

Or install sd0x-dev-flow, the plugin that ships this one along with the rest of its 40 skills, 16 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 check-coverage

README.md
[![agentmods](https://agentmods.dev/badge/skills/sd0xdev/sd0x-harness/check-coverage.svg)](https://agentmods.dev/skills/sd0xdev/sd0x-harness/check-coverage)
Your own site
<a href="https://agentmods.dev/skills/sd0xdev/sd0x-harness/check-coverage"><img src="https://agentmods.dev/badge/skills/sd0xdev/sd0x-harness/check-coverage.svg" alt="Measured on agentmods" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 603 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 $0.00027 $0.00603
Opus 5 $0.00014 $0.00302
Sonnet 5 $0.00005 $0.00121
Haiku 4.5 $0.00003 $0.00060

Measured 4d ago against content hash 697803fa6196, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

check-coverage 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 4d 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/check-coverage/SKILL.md · 98 lines

How it starts

The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Test Coverage Analysis

Trigger

  • Keywords: check coverage, test coverage, coverage analysis, coverage gaps, check-coverage

When NOT to Use

  • Test sufficiency review via Codex (use /codex-test-review)
  • Generating tests (use /codex-test-gen)
  • Running tests (use /verify)

Parent Skill Reference

See @skills/test-review/SKILL.md for Codex-based test review workflow.

Agent Dispatch

Agent({
  description: "Assess three-layer test coverage and identify gaps",
  subagent_type: "coverage-analyst",
  prompt: `Assess Unit / Integration / E2E test coverage for the feature docs at: $ARGUMENTS
Follow the steps defined in this skill.`
})

Task

Step 1: Read Feature Documentation

Read specified feature docs. Extract:

  • Feature name and objectives
  • Involved Service / Provider / Entity
  • Core flows and boundary conditions

Step 2: Identify Related Source Code

Search related source code based on feature documentation. Build source code inventory.

Step 3: Map Test Files

Check whether each source file has corresponding tests (unit, integration, e2e).

Step 4: Analyze Coverage Gaps

For each source file:

  1. Read source: Identify public methods, important branches, error handling
  2. Read tests: Identify covered cases
  3. Compare gaps: missing methods, uncovered branches, untested error scenarios

Step 5: Classify and Recommend

Severity Description
🔴 Critical Core logic, data writes, amount calculations
🟠 Major Important branches, error handling
🟡 Minor Edge cases, utility functions
⚪ Nice-to-have Logging, formatting

Output

# Test Coverage Analysis Report

## Feature Overview
- Feature name: <from documentation>
- Documentation path: $ARGUMENTS
- Related modules: <list>

## Current Coverage
| Module | Source Path | Test Path | Coverage Status |
|--------|------------|-----------|----------------|

## Coverage Gaps
### 🔴 Critical
### 🟠 Major
### 🟡 Minor

## Recommended New Tests
| Priority | Test Type | Test Case | Target File |
|----------|-----------|-----------|-------------|

## Coverage Summary
| Metric | Status |
|--------|--------|
| Feature coverage | X/Y (Z%) |
| Happy path | ✅/❌ |
| Error path | ✅/❌ |
| Edge cases | ✅/❌ |

Read the full file on GitHub · 98 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. 4d ago First seen · 98 lines · 27 tokens per session scan A 697803fa6196

Subscribe to this mod's changes

check-coverage is a skill published in the GitHub repository sd0xdev/sd0x-harness (188 stars, last pushed today), licensed MIT. It adds 27 tokens to every session and 603 once invoked, about $0.0001 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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