seo-ecommerce (M18)

Conditional commerce module: it only runs when commerce signals are detected, then audits and completes product structured data. Reference: references/schema-tier1.md (Product + Offer, Review/AggregateRating rows).

Audits

Working from the PageSnapshot (rendered_dom if present, else raw_html):

1. Commerce gate: detect commerce signals (price/currency text, add-to-cart/buy controls, Product/Offer schema, og:type=product). If none, every M18 finding is not_applicable (severity 0) — do not force product schema onto non-commerce pages.
2. Product + Offer: Product has name, image; Offer has price, priceCurrency, availability (schema.org/InStock etc.). Per references/schema-tier1.md.
3. AggregateRating / Review: if ratings are visibly shown, expect AggregateRating (ratingValue, reviewCount/bestRating) and/or Review (author). Never mark up ratings not visible on the page.
4. Page → schema → feed consistency (Tier 2): schema price/priceCurrency/availability must match visible on-page values and the Merchant Center feed. Mismatches risk disapproval and lost rich results.
5. Faceted navigation: filter/sort URLs (?color=, ?sort=) should canonicalize to the clean product/category URL or be noindex, to avoid index bloat and duplicate-content dilution.
6. Variants / ProductGroup: multi-variant products should use ProductGroup with hasVariant and variesBy, not duplicate standalone Product blocks per SKU.

Fixes

• AUTO (fixable: auto): generate complete, valid Product/Offer/AggregateRating JSON-LD inferred from the DOM (name, image, price, currency, availability, visible rating) inside a single @graph with a stable @id. The block is a diff for fix.
• PROPOSED (fixable: proposed): canonical/noindex tags for faceted URLs and ProductGroup restructuring — drafts requiring per-item accept.
• ADVISORY (fixable: advisory): price / availability mismatches between page, schema, and feed — the store backend/feed is the source of truth, so the tool never writes these. Never invent prices, currencies, availability, or ratings — ask the user or leave a clearly-marked TODO placeholder.

Verification

• Offline: node ${CLAUDE_SKILL_DIR}/../../scripts/validate-jsonld.mjs --url <u> (schema_validator) — JSON validity + required Product/Offer properties.
• Tier 1: Google Rich Results Test / schema.org validator (rich_results_api) for merchant-listing eligibility.
• Tier 2: Merchant Center feed diff — compare schema vs feed price/availability. When the required data tier (feed/API) is unavailable, status is needs_api, never a false pass.

Findings

Emit findings per schema/finding.schema.json. Severity 5 on ecommerce pages, 0 (not_applicable) otherwise; axis both. Examples:

• M18.offer.missing_price — Product without Offer.price/priceCurrency (status fail, severity 5, fixable: auto, axis both, confidence established).
• M18.offer.price_feed_mismatch — schema price differs from on-page/feed price (status warn, severity 5, fixable: advisory, axis both, confidence directional; needs feed → may be needs_api).
• M18.facets.uncanonicalized — indexable faceted URLs lack canonical/noindex (status warn, severity 5, fixable: proposed, axis both, confidence directional).

Each finding: evidence.observed quotes the page (e.g. the rendered price text or the offending ?filter= URL); verification.reproduce is a runnable command; expected_impact is banded + confidence-tagged (no naked %).

Honesty

• AggregateRating/Review markup does not guarantee star rich results — Google shows them at its discretion and gates them by policy; don't promise stars from markup alone.
• Faceted-URL hygiene reduces crawl/index waste but is not a direct ranking factor — frame as directional, not a guaranteed gain.
• Keep schema strictly consistent with visible content and the product feed; fabricated or feed-mismatched values invite Merchant disapproval, not a win.