Agent skill

Coverage Investigation

Investigate and improve code coverage for the wado-compiler crate.

MITAuto-check passedTesting & QA

Install Coverage Investigation

skills CLI

$ npx skills add wado-lang/wado --skill coverage-investigation -a claude-code

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

GitHub CLI

$ gh skill install wado-lang/wado coverage-investigation --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/wado-lang/wado.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/coverage-investigation .claude/skills/coverage-investigation && 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 "coverage-investigation" agent skill from https://github.com/wado-lang/wado/tree/main/.claude/skills/coverage-investigation into .claude/skills/coverage-investigation/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "coverage-investigation", 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/wado-lang/wado/tree/main/.claude/skills/coverage-investigation

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 wado-lang/wado --skill coverage-investigation -a codex

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

GitHub CLI

$ gh skill install wado-lang/wado coverage-investigation --agent codex

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

Manual copy

$ git clone --depth 1 https://github.com/wado-lang/wado.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.claude/skills/coverage-investigation .agents/skills/coverage-investigation && 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 "coverage-investigation" agent skill from https://github.com/wado-lang/wado/tree/main/.claude/skills/coverage-investigation into .agents/skills/coverage-investigation/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "coverage-investigation", 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 wado-lang/wado --skill coverage-investigation -a cursor

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

GitHub CLI

$ gh skill install wado-lang/wado coverage-investigation --agent cursor

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

Manual copy

$ git clone --depth 1 https://github.com/wado-lang/wado.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.claude/skills/coverage-investigation .cursor/skills/coverage-investigation && 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 "coverage-investigation" agent skill from https://github.com/wado-lang/wado/tree/main/.claude/skills/coverage-investigation into .cursor/skills/coverage-investigation/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "coverage-investigation", 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/wado-lang/wado.git --path .claude/skills/coverage-investigation

--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 wado-lang/wado --skill coverage-investigation -a gemini-cli

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

GitHub CLI

$ gh skill install wado-lang/wado coverage-investigation --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/wado-lang/wado.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.claude/skills/coverage-investigation .gemini/skills/coverage-investigation && 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 "coverage-investigation" agent skill from https://github.com/wado-lang/wado/tree/main/.claude/skills/coverage-investigation into .gemini/skills/coverage-investigation/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "coverage-investigation", 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 wado-lang/wado coverage-investigation

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 wado-lang/wado --skill coverage-investigation -a github-copilot

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

Manual copy

$ git clone --depth 1 https://github.com/wado-lang/wado.git skills-src && mkdir -p .github/skills && cp -r skills-src/.claude/skills/coverage-investigation .github/skills/coverage-investigation && 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 "coverage-investigation" agent skill from https://github.com/wado-lang/wado/tree/main/.claude/skills/coverage-investigation into .github/skills/coverage-investigation/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "coverage-investigation", 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 wado-lang/wado --skill coverage-investigation -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 wado-lang/wado coverage-investigation --agent opencode

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

Manual copy

$ git clone --depth 1 https://github.com/wado-lang/wado.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.claude/skills/coverage-investigation .opencode/skills/coverage-investigation && 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 "coverage-investigation" agent skill from https://github.com/wado-lang/wado/tree/main/.claude/skills/coverage-investigation into .opencode/skills/coverage-investigation/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "coverage-investigation", 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: coverage-investigation
GitHub stars: 117
Token cost: ~1.1k tokens
SKILL.md length: 394 words
Files: 1
Skills in repo: 15
Repo updated: Oct 10, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Investigate and improve code coverage for the wado-compiler crate.

Works in 6 steps: Collect Coverage Data → Identify Low-Coverage Files → Classify Coverage Gaps → …
Any question about what the tests do and do not reach
Calls cargo, jq and rg
Dead code included

What it does

Coverage Investigation is an agent skill from wado-lang/wado. Investigate and improve code coverage for the wado-compiler crate. Use for any question about what the tests do and do not reach, dead code included.

Its SKILL.md is about 1.1k 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. It works with WebAssembly. The repository describes itself as: The Wado Programming Language. The licence is MIT.

When your agent uses it

Any question about what the tests do and do not reach
Dead code included

Example prompts

“/coverage-investigation”

Workflow steps

6 steps, taken from the step headings in SKILL.md.

Collect Coverage Data
Identify Low-Coverage Files
Classify Coverage Gaps
Analyze a Specific File
Add E2E Tests
Verify Improvement

What it can do on your machine

Read from SKILL.md and the folder at commit 8ccc675. 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
Shell commands in SKILL.md call:
- cargo
- jq
- rg
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Coverage Investigation loads about 1.1k tokens when it runs. Until then it costs about 43 tokens; SKILL.md has 394 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~43
When it runs · the whole SKILL.md, loaded when a task matches: ~1.1k

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 wado-lang/wado at commit 8ccc675, republished under its MIT licence (© wado-lang). 394 words, ~1,127 tokens.

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

name: coverage-investigation
description: Investigate and improve code coverage for the wado-compiler crate. Use for any question about what the tests do and do not reach, dead code included.

Coverage Investigation Methodology

Step 1: Collect Coverage Data

Use cargo-llvm-cov to generate line-level coverage. The tool must be installed via cargo install cargo-llvm-cov.

Each cargo llvm-cov that is not report runs the whole test suite again, so run the tests once and read every report from that run:

cargo llvm-cov clean --workspace   # a stale profile would merge into this run
cargo llvm-cov --no-report -p wado-compiler -p wado-compiler-tests
cargo llvm-cov report --html                                   # target/llvm-cov/html/
cargo llvm-cov report --json --output-path scratchpad/cov.json
jq '.data[0].totals.lines' scratchpad/cov.json                  # overall

Step 2: Identify Low-Coverage Files

Sort files by uncovered line count to find the biggest improvement opportunities:

jq -r '.data[0].files[] | "\(.summary.lines.count - .summary.lines.covered)\t\(.summary.lines.percent | round)%\t\(.filename)"' \
  scratchpad/cov.json | sort -rn | head -30

Focus on files with:

High absolute uncovered lines (biggest bang for buck)
Low percentage but meaningful code (not just error paths)

Step 3: Classify Coverage Gaps

For each low-coverage file, classify gaps into categories:

Category	Action	Coverage Impact
Dead code	Delete it	Immediate improvement, no test needed
Untested language features	Add e2e test fixtures	Medium effort, high impact
Error handling paths	Add `compile_error` test fixtures	Low effort
Optimizer-specific paths	Add `wir_expect`/`wir_not_expect` tests	Medium effort
Edge cases in codegen	Add targeted e2e tests	Varies

Step 4: Analyze a Specific File

To see exactly which lines are uncovered in a file:

# lcov from the same run
cargo llvm-cov report --lcov --output-path scratchpad/lcov.info

# Or read the HTML report from Step 1:
# target/llvm-cov/html/src/synthesis/inspect.rs.html etc.

To find dead code (functions never called):

# Check if a function has any callers
rg 'function_name' wado-compiler/src/ --type rust

Step 5: Add E2E Tests

E2E tests are .wado files in wado-compiler/tests/fixtures/. Each file has a __DATA__ section with JSON expectations.

Guidelines for test files:

Name files based on language features, not compiler components (e.g., closure_nested.wado not codegen_closure.wado)
Prefer adding test cases to existing fixture files when the feature group matches
Each fixture group shares a filename prefix (e.g., closure_*, global_*, match_*)
After adding new files: touch wado-compiler/tests/e2e.rs to trigger rediscovery

Test patterns that maximize coverage:

test "..." { ... } with {"test": {}} — exercises codegen without needing stdout
compile_error tests — exercise error reporting paths
wir_expect:O2 / wir_not_expect:O2 — exercise optimizer paths
Template strings with {expr:?} — exercise inspect/display synthesis

Show full SKILL.md (121 more words)Show less

Step 6: Verify Improvement

After changes, run Step 1 again and compare jq '.data[0].totals.lines.percent' scratchpad/cov.json with the earlier total.

Key Insights from Past Investigations

synthesis/inspect.rs (~1400 lines) has dead code for type variants that never appear in practice (e.g., Never type inspect). Deleting dead code directly improves coverage.
codegen.rs and emit.rs are the largest files but have relatively high coverage. Incremental improvements here require many targeted tests.
The compiler's test suite is driven by datatest_mini which discovers .wado fixtures at compile time — new files need touch wado-compiler/tests/e2e.rs.
wado test runs test-world fixtures; wado run runs CLI-world fixtures. Choose the right world for your test.
Coverage runs all optimization levels by default in CI; locally only O0 and O2 run unless WADO_FULL_TEST=1.

Files

Just SKILL.md in .claude/skills/coverage-investigation of wado-lang/wado.

Open the folder on GitHubat commit 8ccc675

Compare with similar skills

Coverage Investigation 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.

Coverage Investigation compared with similar skills
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Test Writing WorkflowiOfficeAI/AionUi	33k	1 repos	~1.2k	Automated safety check: Pass	Apache-2.0	1 mo ago
Evaluate PR Testsdotnet/maui	23k	—	~2.9k	Automated safety check: Pass	MIT	today
Update V86felixrieseberg/windows95	24k	—	~1.7k	Automated safety check: Pass	Custom licence	1 mo ago
Requirementsrizsotto/Bear	6.5k	—	~2k	Automated safety check: Pass	GPL-3.0	2 days ago

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Questions about Coverage Investigation

What does Coverage Investigation do?

Investigate and improve code coverage for the wado-compiler crate. Coverage Investigation is an agent skill from wado-lang/wado. Investigate and improve code coverage for the wado-compiler crate.

When should I use Coverage Investigation?

Coverage Investigation fits situations like: any question about what the tests do and do not reach; dead code included.

How do I install Coverage Investigation in Claude Code?

Run `npx skills add wado-lang/wado --skill coverage-investigation -a claude-code`. Or copy the skill folder (.claude/skills/coverage-investigation in wado-lang/wado) into .claude/skills/coverage-investigation in your project. Claude Code loads it when a task matches its description.

How do I install Coverage Investigation in Codex?

Run `npx skills add wado-lang/wado --skill coverage-investigation -a codex`. Or copy the skill folder (.claude/skills/coverage-investigation in wado-lang/wado) into .agents/skills/coverage-investigation in your project. Codex loads it when a task matches its description.

Can I use Coverage Investigation 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 wado-lang/wado --skill coverage-investigation -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/coverage-investigation, .gemini/skills/coverage-investigation, .github/skills/coverage-investigation and .opencode/skills/coverage-investigation in your project.

What does Coverage Investigation need to run?

Going by SKILL.md and its folder, Coverage Investigation needs the command-line tools its instructions call (cargo, jq and rg).

Does Coverage Investigation access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Coverage Investigation 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 Coverage Investigation use?

Coverage Investigation is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Coverage Investigation use?

About 1.1k tokens (SKILL.md is roughly 4.5k 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 Coverage Investigation?

Skills that share tags, products or a category with Coverage Investigation: Dotnet Testing (novotnyllc/dotnet-artisan, 232 stars), Test Writing Workflow (iOfficeAI/AionUi, 33k stars), Evaluate PR Tests (dotnet/maui, 23k stars) and Update V86 (felixrieseberg/windows95, 24k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Coverage Investigation?

wado-lang (a GitHub organization) maintains it in wado-lang/wado, which has 117 GitHub stars. The repository holds 15 skills in this directory. The repository was last updated on October 10, 2026.

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

Install Coverage Investigation

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Coverage Investigation Methodology

Step 1: Collect Coverage Data

Step 2: Identify Low-Coverage Files

Step 3: Classify Coverage Gaps

Step 4: Analyze a Specific File

Step 5: Add E2E Tests

Step 6: Verify Improvement

Key Insights from Past Investigations

Files

Compare with similar skills

Similar skills

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Related

Questions about Coverage Investigation