How do I install the Coverage skill?

Run npx skillmds@latest add tomevault-io/coverage-4 in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Coverage safe to use?

This skill has not completed SkillMD's automated safety review yet. Independent scanners report: SkillSpector: PASS, Skill Scanner: PASS. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Coverage?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Coverage free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Coverage?

tomevault-io (@tomevault-io) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Coverage by tomevault-io — Agent Skill

Name: Coverage
Author: tomevault-io

Coverage

Check test coverage for unstaged changes. Use when user asks to "check coverage", "/coverage", or wants to see which unstaged changes lack test coverage. Don't use for projects without lcov coverage output, running the full test suite without coverage, or checking coverage of already-committed changes. Use when this capability is needed.

tomevault-io Updated Sep 17, 2026

File contents

Coverage Check

Context

Run in parallel:

git diff --name-only - get unstaged files
git diff -U0 --no-color - get changed line numbers

Commands

Sequential:

npm run test:ci - vitest with coverage
npm run coverage:report - generate lcov/text reports

Workflow

Get unstaged files and line ranges (parallel):
- git diff --name-only
- git diff -U0 --no-color
Run coverage:
- npm run test:ci
- npm run coverage:report

Save diff to a temp file, then run:

git diff -U0 --no-color > /tmp/changes.diff
python3 scripts/parse-lcov.py --lcov coverage/lcov.info --diff /tmp/changes.diff

Report uncovered lines from stdout: file.ts:42
Summary from stderr: X/Y changed lines covered

LCOV Format

Parse coverage/lcov.info:

SF:src/utils/helper.ts
DA:10,1    # line 10, covered (hit 1 time)
DA:11,0    # line 11, NOT covered
DA:12,5    # line 12, covered (hit 5 times)
end_of_record

Key fields:

SF: -- source file path
DA:line,hits -- 0 = uncovered, >0 = covered
end_of_record -- end of file section

Match SF: paths to git diff files. For each changed line, check DA: entry. If hits is 0, report as uncovered.

Anti-Rationalization

Excuse	Rebuttal
"Coverage doesn't guarantee quality"	True, but uncovered code guarantees zero automated verification.
"It's just a config change"	Config changes break production too. If there's logic, check coverage.
"100% is overkill"	Nobody asked for 100%. Check that changed lines are covered.
"The test suite is already green"	Green suite with uncovered changes = false confidence.

Rules

Only analyze unstaged changes (git diff)
Use sequential commands: test:ci then coverage:report
Use scripts/parse-lcov.py to parse lcov data and map to changed lines
Report uncovered lines: file.ts:42
Ignore files without coverage data (non-code files)

Error Handling

npm run test:ci fails -- report test failures and stop
coverage/lcov.info not found -- verify coverage.reporter includes lcov in test runner config
git diff returns no changes -- report no unstaged changes to check

Converted and distributed by TomeVault — claim your Tome and manage your conversions.

---name: coverage-4description: Check test coverage for unstaged changes. Use when user asks to "check coverage", "/coverage", or wants to see which unstaged changes lack test coverage. Don't use for projects without lcov coverage output, running the full test suite without coverage, or checking coverage of already-committed changes. Use when this capability is needed.---# Coverage Check## ContextRun in parallel:- `git diff --name-only` - get unstaged files- `git diff -U0 --no-color` - get changed line numbers## CommandsSequential:1. `npm run test:ci` - vitest with coverage2. `npm run coverage:report` - generate lcov/text reports## Workflow1. Get unstaged files and line ranges (parallel): - `git diff --name-only` - `git diff -U0 --no-color`2. Run coverage: - `npm run test:ci` - `npm run coverage:report`3. Save diff to a temp file, then run: ```bash git diff -U0 --no-color > /tmp/changes.diff python3 scripts/parse-lcov.py --lcov coverage/lcov.info --diff /tmp/changes.diff ```4. Report uncovered lines from stdout: `file.ts:42`5. Summary from stderr: X/Y changed lines covered## LCOV FormatParse `coverage/lcov.info`:```SF:src/utils/helper.tsDA:10,1 # line 10, covered (hit 1 time)DA:11,0 # line 11, NOT coveredDA:12,5 # line 12, covered (hit 5 times)end_of_record```Key fields:- `SF:` -- source file path- `DA:line,hits` -- `0` = uncovered, `>0` = covered- `end_of_record` -- end of file sectionMatch `SF:` paths to `git diff` files. For each changed line, check `DA:` entry. If `hits` is `0`, report as uncovered.## Anti-Rationalization| Excuse | Rebuttal ||---|---|| "Coverage doesn't guarantee quality" | True, but uncovered code guarantees zero automated verification. || "It's just a config change" | Config changes break production too. If there's logic, check coverage. || "100% is overkill" | Nobody asked for 100%. Check that *changed* lines are covered. || "The test suite is already green" | Green suite with uncovered changes = false confidence. |## Rules- Only analyze unstaged changes (`git diff`)- Use sequential commands: `test:ci` then `coverage:report`- Use `scripts/parse-lcov.py` to parse lcov data and map to changed lines- Report uncovered lines: `file.ts:42`- Ignore files without coverage data (non-code files)## Error Handling- `npm run test:ci` fails -- report test failures and stop- `coverage/lcov.info` not found -- verify `coverage.reporter` includes `lcov` in test runner config- `git diff` returns no changes -- report no unstaged changes to check---> Converted and distributed by [TomeVault](https://tomevault.io/claim/helderberto) — claim your Tome and manage your conversions.

Frequently asked questions