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L1 · Transport: l1-mixed-content · l1-no-hsts · l1-no-compression · l1-slow-ttfb · l1-xrobots-noindex · l1-missing-vary · l1-mixed-active-script · l1-meta-refresh · l1-html-oversize · l1-cookie-wall · l1-fake-500 · l1-no-cache-control · l1-no-charset · l1-no-etag · l1-wrong-charset

L2 · Crawlability: l2-robots-blocks-css · l2-robots-blocks-section · l2-soft-404 · l14-broken-source

L3 · Head Tags: l14-no-meta-desc

L4 · Indexability: l4-meta-noindex · l4-canonical-to-noindex · l4-canonical-chain · l4-canonical-to-404 · l4-meta-header-conflict · l4-missing-canonical-dupe

L7 · Schema: l7-schema-missing-author · l7-schema-url-mismatch · l7-schema-js-only · l7-schema-deprecated-faq · l7-schema-wrong-type · l7-schema-malformed · l7-schema-required-fields · l7-schema-recommended-fields · l7-schema-dates-invalid · l7-schema-image-404 · l7-breadcrumb-missing · l7-breadcrumb-mismatch · l7-sameas-missing · l7-sameas-404

L9 · Mobile: l9-viewport-fixed · l9-tap-targets-small

L12 · Security: l12-mixed-content-asset · l12-missing-security-headers · l12-insecure-form-action

L15 · Authorship: l15-no-byline · l15-author-string · l15-author-404 · l15-publisher-missing

L18 · Crawler Access: l18-waf-vercel-challenge · l18-just-a-moment-editorial

Clean twins: clean-canonical · clean-schema · clean-robots · clean-hreflang-en · clean-pagination · evidence-stability-l7-recommended-fields

Support routes: l4-canonical-chain-mid · l4-canonical-chain-end

L4 · Indexability: l4-canonical-multiple

This route is deliberately defective: Two conflicting canonical tags on one page

l4-canonical-multiple

Emits two <link rel="canonical"> tags with different hrefs. Google picks one non-deterministically — the fix is almost always to delete the duplicate.