First-match-wins evaluation
When multiple rules target the same collection/sort combination, the system uses a conditions-first evaluation order: rules with contextual conditions are always evaluated before rules without conditions (default/catch-all rules). Among rules of the same type, evaluation follows creation order. This means a default rule will never block a more specific conditional rule from matching, regardless of when each rule was created. Example scenario:Among rules that all have contextual conditions, evaluation follows creation order. The same applies among default rules. If you need to change precedence between rules of the same type, recreate them in the desired order.
Overlap detection validation
To prevent conflicting merchandising rules, the system validates that contextual conditions don’t overlap when creating or updating rules. This ensures that only one rule can match a given visitor at any time. What constitutes overlapping conditions: The system analyzes the contextual conditions of all existing rules for the same collection/sort combination and determines if the new rule’s conditions could match the same visitor as an existing rule. Non-overlapping conditions (allowed):country == USandcountry == CA(different equality values)country in [US, CA]andcountry in [UK, DE](no common values)source == klaviyoandsource == google(different marketing sources)
country == USandcountry == US(identical conditions)country in [US, CA]andcountry in [CA, UK](common value: CA)country == USandcountry in [US, CA](US is in the list)
The overlap detection uses heuristic analysis and may not catch all complex overlapping scenarios with deeply nested OR conditions. The validation provides best-effort protection while allowing legitimate non-overlapping rules to coexist.