How do I install the Shaka Perf Add Coverage skill?

Run npx skillmds@latest add shakacode/shaka-perf-add-coverage 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 Shaka Perf Add Coverage safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Shaka Perf Add 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 Shaka Perf Add Coverage free to use?

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

Who published Shaka Perf Add Coverage?

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

Shaka Perf Add Coverage by shakacode

Name: Shaka Perf Add Coverage
Author: shakacode

Shaka Perf Add Coverage

Use when source code is available and the user asks to add ShakaPerf A/B tests or improve A/B tests coverage for specified UI components or rendered states. Also use when asked to deduplicate A/B tests. Also use when asked to measure FE performance.

shakacode Updated Sep 17, 2026

File contents

shaka-perf-add-coverage

Your goal is to add tests without unnecessarily bloating the test suite. The endgoal is all the interested components should be screenshoted without duplication (happy paths only).

REQUIRED SUB-SKILL: Use shaka-perf-coverage to estimate coverage, save the pre-edit baseline, read snapshots, and compare the final coverage.

The loop

Run shaka-perf audit --help, shaka-perf compare --help, and shaka-perf troubleshoot --help
IMPORTANT find other ab tests that cover this element already. Produce a comma-separated tests filter (referenced as relevant-tests). 1.a Produce relevant-sources for the components under test (defined in shaka-perf-coverage). Keep it narrow and identical across baseline comparisons. A source missing from it is a hole you will never see.
Use skill /shaka-perf-coverage to audit relevant-tests and save the BEFORE baseline for relevant-sources, before editing tests.
If the element is fully covered by estimated coverage, check it is actually visible on screenshots:
- 3.a. Find the element's line in the snapshot and read its screenshot cell and reason (table in shaka-perf-coverage).
- 3.b. Use shaka-perf troubleshoot when the snapshot is ambiguous or you need to see the live page — occlusion is a sampled estimate, measured only inside the current viewport. Wait for the Test completed log entry before inspecting.
- 3.c. Generate screenshots with shaka-perf compare --categories=visreg --filter=<relevant-tests> --controlURL=<experiment-url> and review the screenshots visually.
If the screenshot cell is below 100%, fix it per the reason table. If the element is dead code, DO NOT EDIT PROD FILES TO MAKE IT RENDERED.
If these fixes are not enough for the coverage and you genuinely need to add more tests, write them and add them to relevant-tests.
If relevant-tests violate any rules in writing-good-ab-tests.md, fix them
Run shaka-perf compare --categories=visreg --filter=<relevant-tests> --controlURL=<experiment-url> --burn 3 and fix all the flakiness coming from tests themselves. Do not fix flaky errors on the page or in the server, instead let the user know there is a bug and give them reproduction cmd (the failing --burn command you were running). Tell them that the problem is in the App, not in the tests.
Scan steps 3-6 using a subagent to make it adversarial, see if you missed somethings
Re-audit, save the AFTER baseline, and diff it against the BEFORE (per shaka-perf-coverage). Restart from 3 with the AFTER as the new BEFORE.

Stop the loop when all the components are fully covered by hi-quality tests that don't flake.

Caveat: audit-results/ and compare-results/ keep unit dirs from earlier filtered runs and their names are not chronological; read only the ids listed in each run's report.json.

---name: shaka-perf-add-coveragedescription: Use when source code is available and the user asks to add ShakaPerf A/B tests or improve A/B tests coverage for specified UI components or rendered states. Also use when asked to deduplicate A/B tests. Also use when asked to measure FE performance.---# shaka-perf-add-coverageYour goal is to add tests without unnecessarily bloating the test suite. The endgoal is all the interested components should be screenshoted without duplication (happy paths only).**REQUIRED SUB-SKILL:** Use `shaka-perf-coverage` to estimate coverage, save the pre-edit baseline, read snapshots, and compare the final coverage.## The loop0. Run `shaka-perf audit --help`, `shaka-perf compare --help`, and `shaka-perf troubleshoot --help`1. IMPORTANT find other ab tests that cover this element already. Produce a comma-separated tests filter (referenced as `relevant-tests`).1.a Produce `relevant-sources` for the components under test (defined in `shaka-perf-coverage`). Keep it narrow and identical across baseline comparisons. A source missing from it is a hole you will never see.2. Use skill `/shaka-perf-coverage` to audit `relevant-tests` and save the BEFORE baseline for `relevant-sources`, before editing tests.3. If the element is fully covered by estimated coverage, check it is actually visible on screenshots: - 3.a. Find the element's line in the snapshot and read its screenshot cell and reason (table in `shaka-perf-coverage`). - 3.b. Use `shaka-perf troubleshoot` when the snapshot is ambiguous or you need to see the live page — occlusion is a sampled estimate, measured only inside the current viewport. Wait for the `Test completed` log entry before inspecting. - 3.c. Generate screenshots with `shaka-perf compare --categories=visreg --filter=<relevant-tests> --controlURL=<experiment-url>` and review the screenshots visually.4. If the screenshot cell is below 100%, fix it per the reason table. If the element is dead code, DO NOT EDIT PROD FILES TO MAKE IT RENDERED.5. If these fixes are not enough for the coverage and you genuinely need to add more tests, write them and add them to `relevant-tests`.6. If `relevant-tests` violate any rules in `writing-good-ab-tests.md`, fix them7. Run `shaka-perf compare --categories=visreg --filter=<relevant-tests> --controlURL=<experiment-url> --burn 3` and fix all the flakiness coming from tests themselves. Do not fix flaky errors on the page or in the server, instead let the user know there is a bug and give them reproduction cmd (the failing --burn command you were running). Tell them that the problem is in the App, not in the tests.8. Scan steps 3-6 using a subagent to make it adversarial, see if you missed somethings9. Re-audit, save the AFTER baseline, and `diff` it against the BEFORE (per `shaka-perf-coverage`). Restart from 3 with the AFTER as the new BEFORE.Stop the loop when all the components are fully covered by hi-quality tests that don't flake.Caveat: `audit-results/` and `compare-results/` keep unit dirs from earlier filtered runs and their names are not chronological; read only the ids listed in each run's `report.json`.

Frequently asked questions