core-web-vitals SKILL.md skillB
core-web-vitals from frankxai/claude-skills-library is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add frankxai/claude-skills-library/core-web-vitals@git:20261014.6dd6f73Pins git:20261014.6dd6f73 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- B, 16 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- frankxai/claude-skills-library
- Path
packs/web-excellence/skills/core-web-vitals/SKILL.md- Versions recorded
- 2
- Latest version
- git:20261014.6dd6f73, committed Oct 14, 2026
- First version recorded
- Jul 27, 2026
- Size
- 4,795 bytes
- Repository stars
- 48
- License
- MIT
Measure and hold a real performance budget on a web page — LCP, INP, CLS, bundle weight, font and image loading. Use when a change touches images, fonts, above-the-fold markup, client components, third-party scripts, or any list that can grow; when a page feels slow; or before shipping a new landing page or hero. Produces measured numbers from Lighthouse or the build output, never estimates. Also states honestly when measurement is impossible in the current environment instead of guessing.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Core Web Vitals The rule: **report measurements or report that you could not measure.** A performance claim with no number attached is noise, and a number you did not observe is worse than no number. ## Targets Field thresholds (what Google grades on, 75th percentile of real users): | Metric | Good | Needs work | Poor | |---|---|---|---| | LCP — Largest Contentful Paint | ≤ 2.5s | 2.5–4.0s | > 4.0s | | INP — Interaction to Next Paint | ≤ 200ms | 200–500ms | > 500ms | | CLS — Cumulative Layout Shift | ≤ 0.1 | 0.1–0.25 | > 0.25 | Lab numbers from Lighthouse on a dev build run hotter than field numbers. Treat a lab pass as necessary, not sufficient, and say which kind you measured. Budget for a marketing or landing page, on top of the metrics: - First-load JS for the route: **≤ 200 kB gzipped**. Next.js prints this per route in the build output — that is a free measurement, always take it. - Hero image: served in AVIF or WebP, sized to its container, `priority` set. - Web fonts: at most two families, `font-display: swap`, preloaded if above the fold, subset to the characters actually used. ## How to measure Cheapest first. Stop when you have a number. …
Read the whole file at its exact version.
How to install
mdr add frankxai/claude-skills-library/core-web-vitals@sha256:097574370ff81cd0The line at the top of this page pins the label git:20261014.6dd6f73, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_t4lr2eec7dbjpi6b)
3 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 2 versions of this file, between Jul 27, 2026 and Oct 14, 2026, about one every 79 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20261014.6dd6f73 latest | 2026-10-14 | 6dd6f73 | 4,795 B | B | view · diff |
| git:20260727.cb1d1d1 | 2026-07-27 | cb1d1d1 | 4,369 B | B | view |
Audit of the latest version
- fail: No script tag (matched: <script)
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (4795 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
Starting a new one? Use a template for SKILL.md on mdpantry, which passes every one of these checks and says what to change in it.
Source
frankxai/claude-skills-library · 48 stars · license MIT · pushed 2026-11-04 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_t4lr2eec7dbjpi6b GET https://markdownregistry.com/api/v1/resolve?ref=frankxai/claude-skills-library/core-web-vitals GET https://markdownregistry.com/api/v1/blob/097574370ff81cd0a8fa0b3f5605dd10140fc84f96f60910e80b14614aed3cea
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.
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