Agent skill

Experimental Read Code Coverage Metrics

Retrieves and analyzes Chromium per-CL code coverage data from the Findit API.

BSD-3-ClauseAuto-check passedTesting & QA

Install Experimental Read Code Coverage Metrics

skills CLI

$ npx skills add nwjs/chromium.src --skill experimental-read-code-coverage-metrics -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install nwjs/chromium.src experimental-read-code-coverage-metrics --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/nwjs/chromium.src.git skills-src && mkdir -p .claude/skills && cp -r skills-src/agents/skills/experimental-read-code-coverage-metrics .claude/skills/experimental-read-code-coverage-metrics && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "experimental-read-code-coverage-metrics" agent skill from https://github.com/nwjs/chromium.src/tree/main/agents/skills/experimental-read-code-coverage-metrics into .claude/skills/experimental-read-code-coverage-metrics/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "experimental-read-code-coverage-metrics", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/nwjs/chromium.src/tree/main/agents/skills/experimental-read-code-coverage-metrics

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add nwjs/chromium.src --skill experimental-read-code-coverage-metrics -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install nwjs/chromium.src experimental-read-code-coverage-metrics --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/nwjs/chromium.src.git skills-src && mkdir -p .agents/skills && cp -r skills-src/agents/skills/experimental-read-code-coverage-metrics .agents/skills/experimental-read-code-coverage-metrics && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "experimental-read-code-coverage-metrics" agent skill from https://github.com/nwjs/chromium.src/tree/main/agents/skills/experimental-read-code-coverage-metrics into .agents/skills/experimental-read-code-coverage-metrics/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "experimental-read-code-coverage-metrics", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add nwjs/chromium.src --skill experimental-read-code-coverage-metrics -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install nwjs/chromium.src experimental-read-code-coverage-metrics --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/nwjs/chromium.src.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/agents/skills/experimental-read-code-coverage-metrics .cursor/skills/experimental-read-code-coverage-metrics && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "experimental-read-code-coverage-metrics" agent skill from https://github.com/nwjs/chromium.src/tree/main/agents/skills/experimental-read-code-coverage-metrics into .cursor/skills/experimental-read-code-coverage-metrics/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "experimental-read-code-coverage-metrics", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/nwjs/chromium.src.git --path agents/skills/experimental-read-code-coverage-metrics

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add nwjs/chromium.src --skill experimental-read-code-coverage-metrics -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install nwjs/chromium.src experimental-read-code-coverage-metrics --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/nwjs/chromium.src.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/agents/skills/experimental-read-code-coverage-metrics .gemini/skills/experimental-read-code-coverage-metrics && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "experimental-read-code-coverage-metrics" agent skill from https://github.com/nwjs/chromium.src/tree/main/agents/skills/experimental-read-code-coverage-metrics into .gemini/skills/experimental-read-code-coverage-metrics/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "experimental-read-code-coverage-metrics", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install nwjs/chromium.src experimental-read-code-coverage-metrics

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add nwjs/chromium.src --skill experimental-read-code-coverage-metrics -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/nwjs/chromium.src.git skills-src && mkdir -p .github/skills && cp -r skills-src/agents/skills/experimental-read-code-coverage-metrics .github/skills/experimental-read-code-coverage-metrics && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "experimental-read-code-coverage-metrics" agent skill from https://github.com/nwjs/chromium.src/tree/main/agents/skills/experimental-read-code-coverage-metrics into .github/skills/experimental-read-code-coverage-metrics/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "experimental-read-code-coverage-metrics", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add nwjs/chromium.src --skill experimental-read-code-coverage-metrics -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install nwjs/chromium.src experimental-read-code-coverage-metrics --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/nwjs/chromium.src.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/agents/skills/experimental-read-code-coverage-metrics .opencode/skills/experimental-read-code-coverage-metrics && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "experimental-read-code-coverage-metrics" agent skill from https://github.com/nwjs/chromium.src/tree/main/agents/skills/experimental-read-code-coverage-metrics into .opencode/skills/experimental-read-code-coverage-metrics/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "experimental-read-code-coverage-metrics", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: experimental-read-code-coverage-metrics
GitHub stars: 160
Token cost: ~859 tokens
SKILL.md length: 282 words
Files: 1
Skills in repo: 64
Repo updated: Oct 3, 2026
First seen: Oct 8, 2026
Licence: BSD-3-Clause

At a glance

Retrieves and analyzes Chromium per-CL code coverage data from the Findit API.

Works in 2 steps: Extract CL Details & Run Coverage… → Verify Coverage Artifact: Confirm the…
Tasks that involve Test coverage
SKILL.md covers When to Use This Skill, Inputs (Passed directly in…, Workflow and Output, plus 1 more section
Reaches chromium-review.googlesource.com; needs LUCI_AUTH_TOKEN

What it does

Experimental Read Code Coverage Metrics is an agent skill from nwjs/chromium.src. Retrieves and analyzes Chromium per-CL code coverage data from the Findit API. Records per-CL coverage metrics for all modified source files and extracts unexecuted code lines.

Its SKILL.md is about 860 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Testing & QA, covering Test coverage. The repository describes itself as: Chromium codebase with NW.js modifications. Based on https://chromium.googlesource.com/chromium/src.git. The licence is BSD-3-Clause.

When your agent uses it

Tasks that involve Test coverage

Example prompts

“Use the experimental-read-code-coverage-metrics skill to retrieve and analyzes Chromium per-CL code coverage data from the Findit API”
“/experimental-read-code-coverage-metrics”

Requirements

A credential in LUCI_AUTH_TOKEN

Workflow steps

2 steps, taken from the first numbered list in SKILL.md.

Extract CL Details & Run Coverage Metrics Script: Use
Verify Coverage Artifact: Confirm the script generated the artifact at

What it can do on your machine

Read from SKILL.md and the folder at commit a9e8946. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are bash and json).
From the folder's file list and the shell code blocks in SKILL.md.
Network
Hosts in commands or code, which the agent is likely to contact:
- chromium-review.googlesource.com
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names these keys or tokens, usually read from environment variables:
- LUCI_AUTH_TOKEN
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Experimental Read Code Coverage Metrics loads about 859 tokens when it runs. Until then it costs about 54 tokens; SKILL.md has 282 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~54
When it runs · the whole SKILL.md, loaded when a task matches: ~859

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from nwjs/chromium.src at commit a9e8946, republished under its BSD-3-Clause licence (© nwjs). 282 words, ~859 tokens.

Download SKILL.mdSave it as .claude/skills/experimental-read-code-coverage-metrics/SKILL.md (or your agent's skills folder).

name: experimental-read-code-coverage-metrics
description: Retrieves and analyzes Chromium per-CL code coverage data from the Findit API. Records per-CL coverage metrics for all modified source files and extracts unexecuted code lines.

Read Code Coverage Metrics

This skill fetches and processes code coverage data for a given Gerrit CL and patchset. It uses the live Findit API to retrieve coverage percentages and line-by-line details, records coverage metrics for all modified source files, and extracts the code blocks corresponding to uncovered lines.

When to Use This Skill

Activate this skill when:

Establishing a baseline coverage state for a CL before attempting fixes.
Verifying if coverage has improved after applying changes and re-running try jobs.
You need to know not just the percentage, but which specific lines and code blocks are untested.

Inputs (Passed directly in prompt)

When invoked as a subagent, the parent agent MUST explicitly pass:

cl_url: The full Gerrit CL URL to fetch coverage for (e.g., https://chromium-review.googlesource.com/c/chromium/src/+/7916168).
artifact_path: The destination file path to store the JSON metrics artifact (e.g., scratch/original_metrics.json).
target_files: Optional list of specific target file paths to filter coverage for (e.g., ["chrome/browser/.../CommerceBottomSheetContentMediator.java"]). If omitted, records metrics across all modified source files.

Workflow

Extract CL Details & Run Coverage Metrics Script: Use tools/code_coverage/parse_gerrit_url.py to extract host, project, change, and patchset from cl_url:
bash
```
vpython3 tools/code_coverage/parse_gerrit_url.py <cl_url>
```
Execute fetch_coverage_metrics.py passing the extracted parameters and optional --files filter:
bash
```
vpython3 tools/code_coverage/fetch_coverage_metrics.py --host <host> \
  --project <project> --change <change> --patchset <patchset> \
  --output <artifact_path> --files <target_files>
```

Verify Coverage Artifact: Confirm the script generated the artifact at <artifact_path>. The artifact maps modified source files to their coverage metrics and uncovered lines:

json

{
  "chrome/browser/.../CommerceBottomSheetContentMediator.java": {
    "metrics": {
      "absolute_coverage": 80.0,
      "incremental_coverage": 65.0,
      "absolute_unit_tests_coverage": 80.0,
      "incremental_unit_tests_coverage": 65.0
    },
    "low_coverage_type": [
      "incremental_coverage",
      "incremental_unit_tests_coverage"
    ],
    "uncovered_lines": {
      "77": "    mBottomSheetContent.setConfirmBoxVisible(false);",
      "78": "    mBottomSheetContent.setConfirmButtonEnabled(false);"
    }
  }
}

Output

The skill stores the detailed coverage JSON artifact directly at <artifact_path> (scratch/original_metrics.json, scratch/control_metrics.json, or scratch/fix_metrics.json). It should return a summary message indicating the coverage metrics and unexecuted line counts across modified source files.

Important Considerations

Authentication: If querying private CLs, pass --auth-token or set LUCI_AUTH_TOKEN in the environment.
Error Handling: If the script exits with non-zero status, check stderr for API or decoding failures.

Files

Just SKILL.md in agents/skills/experimental-read-code-coverage-metrics of nwjs/chromium.src.

Open the folder on GitHubat commit a9e8946

Compare with similar skills

Experimental Read Code Coverage Metrics next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Experimental Read Code Coverage Metrics compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Experimental Read Code Coverage Metrics this skillnwjs/chromium.src	160	—	~859	Automated safety check: Pass	BSD-3-Clause	5 days ago
Requirementsrizsotto/Bear	6.5k	—	~2k	Automated safety check: Pass	GPL-3.0	yesterday
Crap Analysisardalis/RiverBooks	135	2 repos	~3.4k	Automated safety check: Pass	None	today
Code Coverages3s-project/s3s	311	—	~789	Automated safety check: Pass	Apache-2.0	today
Project Statusbactopia/bactopia	522	—	~787	Automated safety check: Pass	MIT	2 mo ago
Check Coverageldayton/Dippy	243	—	~403	Automated safety check: Pass	MIT	3 mo ago

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Questions about Experimental Read Code Coverage Metrics

What does Experimental Read Code Coverage Metrics do?

Retrieves and analyzes Chromium per-CL code coverage data from the Findit API. src. Retrieves and analyzes Chromium per-CL code coverage data from the Findit API.

When should I use Experimental Read Code Coverage Metrics?

Experimental Read Code Coverage Metrics fits situations like: tasks that involve Test coverage.

How do I install Experimental Read Code Coverage Metrics in Claude Code?

Run `npx skills add nwjs/chromium.src --skill experimental-read-code-coverage-metrics -a claude-code`. Or copy the skill folder (agents/skills/experimental-read-code-coverage-metrics in nwjs/chromium.src) into .claude/skills/experimental-read-code-coverage-metrics in your project. Claude Code loads it when a task matches its description.

How do I install Experimental Read Code Coverage Metrics in Codex?

Run `npx skills add nwjs/chromium.src --skill experimental-read-code-coverage-metrics -a codex`. Or copy the skill folder (agents/skills/experimental-read-code-coverage-metrics in nwjs/chromium.src) into .agents/skills/experimental-read-code-coverage-metrics in your project. Codex loads it when a task matches its description.

Can I use Experimental Read Code Coverage Metrics in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add nwjs/chromium.src --skill experimental-read-code-coverage-metrics -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/experimental-read-code-coverage-metrics, .gemini/skills/experimental-read-code-coverage-metrics, .github/skills/experimental-read-code-coverage-metrics and .opencode/skills/experimental-read-code-coverage-metrics in your project.

What does Experimental Read Code Coverage Metrics need to run?

Going by SKILL.md and its folder, Experimental Read Code Coverage Metrics needs credentials named LUCI_AUTH_TOKEN. Our summary lists: A credential in LUCI_AUTH_TOKEN.

Does Experimental Read Code Coverage Metrics access the network?

SKILL.md names 1 domain. In commands or code: chromium-review.googlesource.com; the agent is likely to contact it when it follows the instructions. This is read from the text; nothing was executed.

Is Experimental Read Code Coverage Metrics safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Experimental Read Code Coverage Metrics use?

Experimental Read Code Coverage Metrics is published under the BSD-3-Clause licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Experimental Read Code Coverage Metrics use?

About 859 tokens (SKILL.md is roughly 3.4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Experimental Read Code Coverage Metrics?

Skills that share tags, products or a category with Experimental Read Code Coverage Metrics: Requirements (rizsotto/Bear, 6.5k stars), Crap Analysis (ardalis/RiverBooks, 135 stars), Code Coverage (s3s-project/s3s, 311 stars) and Project Status (bactopia/bactopia, 522 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Experimental Read Code Coverage Metrics?

nwjs (a GitHub organization) maintains it in nwjs/chromium.src, which has 160 GitHub stars. The repository holds 64 skills in this directory. The repository was last updated on October 3, 2026.

Source: nwjs/chromium.src on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Experimental Read Code Coverage Metrics

Facts

At a glance

What it does

When your agent uses it

Example prompts

Requirements

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Read Code Coverage Metrics

When to Use This Skill

Inputs (Passed directly in prompt)

Workflow

Output

Important Considerations

Files

Compare with similar skills

Similar skills

More from nwjs/chromium.src

Related

Questions about Experimental Read Code Coverage Metrics