seo-core-web-vitals

Name: seo-core-web-vitals
Author: Hainrixz

29stars2forks

How to install seo-core-web-vitals?

hainrixz/claude-seo-ai/seo-core-web-vitals

$npx -y skills add Hainrixz/claude-seo-ai --skill seo-core-web-vitals

Installs into the current project.

Summary

Audit Core Web Vitals & page performance — measure LCP, INP, and CLS against p75 field thresholds, diagnose render-blocking resources, unoptimized images, and layout-shift sources, and produce prioritized, advisory-only remediation guidance. Module M15. Feeds the Search SEO score

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SKILL.md

1	# seo-core-web-vitals (M15)
2
3	Core Web Vitals are a confirmed Google ranking signal and a proxy for page quality. Thresholds, field-vs-lab honesty rules, and LCP decomposition: `references/cwv-thresholds.md` (follow it exactly).
4
5	## Audits
6	Working from the PageSnapshot (`rendered_dom` if present, else `raw_html`):
7	1. Field CWV at p75 — LCP ≤ 2.5 s, INP ≤ 200 ms (INP replaced FID), CLS ≤ 0.1, all at the 75th percentile of real-user data. All three must pass for a "good" rating. Use the proactive-warning thresholds (LCP > 2.0 s, INP > 160 ms, CLS > 0.08) to `warn` before failing.
8	2. Render-blocking resources — synchronous `<script>` in `<head>` (no `defer`/`async`/`type=module`), blocking `<link rel="stylesheet">`, and `@import` chains that delay first render (LCP/INP risk).
9	3. Unoptimized images — missing `width`/`height` (or `aspect-ratio`), no `loading="lazy"` below the fold, no responsive `srcset`/`sizes`, legacy formats where AVIF/WebP would serve, and a non-preloaded LCP image.
10	4. Layout-shift sources — images/iframes/ads/embeds without reserved dimensions, web-font swap without `font-display`/size-adjust, and content injected above existing content (CLS risk).
11	5. LCP decomposition — attribute LCP to TTFB vs resource load delay vs load duration vs render delay (see `references/cwv-thresholds.md`) so each finding targets the dominant subpart.
12
13	## Fixes (fixable: advisory)
14	Advisory only. Performance fixes touch build config, server, CDN, and runtime JavaScript — high breakage risk — so the tool diagnoses and prioritizes but never auto-edits performance code. For each failing metric, name the specific resource/element causing it and rank fixes by expected leverage (e.g. preload the LCP image, defer non-critical JS, reserve image dimensions). Give framework-specific direction where the stack is known. Never fabricate measured values — if field data is absent, ask the user to supply a PSI/CrUX key or leave a clearly-marked TODO placeholder rather than guessing a metric.
15
16	## Verification
17	- Field (Tier 1): `node ${CLAUDE_SKILL_DIR}/../../scripts/psi-client.mjs --url <u>` calls the PageSpeed Insights API (`loadingExperience`, method `psi_api`); CrUX History via the same client (`crux_api`) for p75 trends. Requires a free API key.
18	- Tier 0 (no key): emit `status: needs_api` for every field-CWV finding, plus clearly-labeled lab heuristics (render-blocking count, missing image dimensions, bundle weight). Label lab signals "lab data — not what Google ranks on"; never present a heuristic as a measured field value.
19	- When the required data tier is unavailable, status is `needs_api` — never a false `pass`.
20
21	## Findings
22	Emit findings per `schema/finding.schema.json`. Examples:
23	- `M15.lcp.exceeds_p75` — field LCP > 2.5 s at p75 (status `fail`, severity 4, `fixable: advisory`, axis `search`, confidence `established`). `evidence.observed` quotes the measured p75 value and the LCP element; `verification.reproduce` runs the psi-client command.
24	- `M15.cls.unsized_image` — image with no `width`/`height` shifting layout (status `warn`, severity 4, `fixable: advisory`, axis `search`, confidence `directional`). `evidence.observed` quotes the `<img>` tag.
25	- `M15.field.needs_api` — no PSI/CrUX key, field CWV unverifiable (status `needs_api`, severity 4, `fixable: advisory`, axis `search`, confidence `established`).
26	Each finding: `evidence.observed` quotes the page/measurement; `verification.reproduce` is the runnable command; `expected_impact` is banded + confidence-tagged (no naked %).
27
28	## Honesty
29	- Lab ≠ field. A single local Lighthouse run is diagnostic only; Google ranks on field (CrUX) p75. Never let a lab number drive the Search score or masquerade as a field result.
30	- CWV is a real but modest tie-breaker signal — it does not override relevance/content quality. Don't promise ranking jumps from a green score; report it as banded `expected_impact`, not a predicted percentage gain.
31	- A "100" lab performance score is not a pass if field p75 fails; only field data settles a CWV finding.

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seo-core-web-vitals

29stars2forks

View on GitHub

How to install seo-core-web-vitals?

hainrixz/claude-seo-ai/seo-core-web-vitals

$npx -y skills add Hainrixz/claude-seo-ai --skill seo-core-web-vitals

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# seo-core-web-vitals (M15)
2
3	Core Web Vitals are a confirmed Google ranking signal and a proxy for page quality. Thresholds, field-vs-lab honesty rules, and LCP decomposition: `references/cwv-thresholds.md` (follow it exactly).
4
5	## Audits
6	Working from the PageSnapshot (`rendered_dom` if present, else `raw_html`):
7	1. Field CWV at p75 — LCP ≤ 2.5 s, INP ≤ 200 ms (INP replaced FID), CLS ≤ 0.1, all at the 75th percentile of real-user data. All three must pass for a "good" rating. Use the proactive-warning thresholds (LCP > 2.0 s, INP > 160 ms, CLS > 0.08) to `warn` before failing.
8	2. Render-blocking resources — synchronous `<script>` in `<head>` (no `defer`/`async`/`type=module`), blocking `<link rel="stylesheet">`, and `@import` chains that delay first render (LCP/INP risk).
9	3. Unoptimized images — missing `width`/`height` (or `aspect-ratio`), no `loading="lazy"` below the fold, no responsive `srcset`/`sizes`, legacy formats where AVIF/WebP would serve, and a non-preloaded LCP image.
10	4. Layout-shift sources — images/iframes/ads/embeds without reserved dimensions, web-font swap without `font-display`/size-adjust, and content injected above existing content (CLS risk).
11	5. LCP decomposition — attribute LCP to TTFB vs resource load delay vs load duration vs render delay (see `references/cwv-thresholds.md`) so each finding targets the dominant subpart.
12
13	## Fixes (fixable: advisory)
14	Advisory only. Performance fixes touch build config, server, CDN, and runtime JavaScript — high breakage risk — so the tool diagnoses and prioritizes but never auto-edits performance code. For each failing metric, name the specific resource/element causing it and rank fixes by expected leverage (e.g. preload the LCP image, defer non-critical JS, reserve image dimensions). Give framework-specific direction where the stack is known. Never fabricate measured values — if field data is absent, ask the user to supply a PSI/CrUX key or leave a clearly-marked TODO placeholder rather than guessing a metric.
15
16	## Verification
17	- Field (Tier 1): `node ${CLAUDE_SKILL_DIR}/../../scripts/psi-client.mjs --url <u>` calls the PageSpeed Insights API (`loadingExperience`, method `psi_api`); CrUX History via the same client (`crux_api`) for p75 trends. Requires a free API key.
18	- Tier 0 (no key): emit `status: needs_api` for every field-CWV finding, plus clearly-labeled lab heuristics (render-blocking count, missing image dimensions, bundle weight). Label lab signals "lab data — not what Google ranks on"; never present a heuristic as a measured field value.
19	- When the required data tier is unavailable, status is `needs_api` — never a false `pass`.
20
21	## Findings
22	Emit findings per `schema/finding.schema.json`. Examples:
23	- `M15.lcp.exceeds_p75` — field LCP > 2.5 s at p75 (status `fail`, severity 4, `fixable: advisory`, axis `search`, confidence `established`). `evidence.observed` quotes the measured p75 value and the LCP element; `verification.reproduce` runs the psi-client command.
24	- `M15.cls.unsized_image` — image with no `width`/`height` shifting layout (status `warn`, severity 4, `fixable: advisory`, axis `search`, confidence `directional`). `evidence.observed` quotes the `<img>` tag.
25	- `M15.field.needs_api` — no PSI/CrUX key, field CWV unverifiable (status `needs_api`, severity 4, `fixable: advisory`, axis `search`, confidence `established`).
26	Each finding: `evidence.observed` quotes the page/measurement; `verification.reproduce` is the runnable command; `expected_impact` is banded + confidence-tagged (no naked %).
27
28	## Honesty
29	- Lab ≠ field. A single local Lighthouse run is diagnostic only; Google ranks on field (CrUX) p75. Never let a lab number drive the Search score or masquerade as a field result.
30	- CWV is a real but modest tie-breaker signal — it does not override relevance/content quality. Don't promise ranking jumps from a green score; report it as banded `expected_impact`, not a predicted percentage gain.
31	- A "100" lab performance score is not a pass if field p75 fails; only field data settles a CWV finding.

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