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seo/canonical-url · Canonical URL

Every route should include a <link rel="canonical"> tag.

Severity: warning

What it checks

Every route should include a <link rel="canonical"> tag (own or inherited through the layout chain). A missing or empty canonical link is flagged.

Why it matters

A canonical URL tells search engines which URL is authoritative, preventing duplicate-content dilution across query-string variants of the same page. (SvelteKit normalizes trailing slashes itself by default, so that particular variant isn’t a concern here.)

How to fix

Add <link rel="canonical"> in <svelte:head>, or set the canonical prop on your meta component:

<svelte:head>
  <link rel="canonical" href="https://example.com/this-page" />
</svelte:head>

Mode differences

Source analysis (the CLI, the dashboard’s static baseline) composes each route’s <head> from <svelte:head> in the page and its layout chain, followed into repo-local components, plus the known meta components (svelte-meta-tags, svelte-seo) and any you declare in metaComponents. A value it cannot read literally ({data.title}) is dynamic, judged by treatDynamicAs. Rendered analysis (the Vite plugin’s build pass, a route you visit in the dashboard) reads the shipped <head>, where every value is literal and treatDynamicAs does not apply; the build pass covers prerendered routes only. When the two disagree, trust the rendered result.

Disabling

Record existing findings in the suppressions file (npx svelte-vitals --update-suppressions), scope the rule per route or path with overrides, or turn it off:

export default {
  rules: {
    'seo/canonical-url': 'off'
  }
};