Publish schema.org ProductGroup structured data with variesBy and isVariantOf/hasVariant properties so shopping agents can correctly resolve size/color/material variants during agentic checkout

Steps

1. Model each variant-bearing item family as a ProductGroup with a stable productGroupID, and each individual purchasable variant as a Product
2. Set variesBy on the ProductGroup to the schema.org property URIs that differ across variants (e.g. https://schema.org/color, https://schema.org/size) rather than plain text labels
3. Choose the nested approach (hasVariant listing variant Products directly on the ProductGroup) for single-page variant selectors, or the separate-pages approach (isVariantOf or inProductGroupWithID on each variant's own page) when each variant has its own URL
4. Ensure every variant Product still carries its own price, availability, and SKU so an agent can select and add the exact correct variant to a cart, not just the parent group
5. Validate the markup against Google's Product Variant structured data guidance to confirm the nested vs. separate-page pattern is applied consistently across the catalog
6. Confirm your ACP/UCP feed pipeline reuses the same productGroupID/variant relationships rather than maintaining a second, inconsistent variant model for agent-specific feeds