A Shopper’s Price Limit Belongs in Retrieval, Not the Reply

A shopper says “under $700.” The catalogue search finds six good matches, but the cheapest is $749. The assistant can write a perfect sentence about budget-friendly choices and still be wrong. The mistake happened before it wrote a word.

Product search often starts with the nouns in a message: snowboard, jacket, desk chair. A price phrase can be reduced to background context while a keyword search returns plausible products. Once those products reach the reply model, asking it to “respect the budget” is a weak repair. The shortlist has already broken the shopper’s rule.

Treat the Ceiling as Part of the Query

Separate the request into product meaning and hard constraints. The product meaning helps rank relevant matches. The ceiling limits which matches are eligible at all. Apply the limit in the catalogue query where the source supports it; otherwise filter the retrieved candidates before ranking and answer generation. Do not let relevance put an over-budget item back into the answer.

This is an ordinary catalogue capability, not a prompt trick. Shopify’s product filter includes a price range, and its range definition has an explicit maximum. A chatbot can use the same principle even when its store has a different search interface: carry the ceiling as structured search input, then verify what came back.

Check the Item That Can Be Bought

A product card may say “from $649,” while the size or finish the shopper wants costs more. Shopify distinguishes a product’s minimum and maximum variant prices. That distinction matters in conversation: a qualifying starting price does not make every variant eligible.

Before naming a choice, check the actual available variant and the currency in which its price is shown. Keep sale and regular prices distinct. If the assistant cannot identify a purchasable choice inside the ceiling, it should not hide behind the product’s lowest possible price. This is the approach we use in HoverBot: the catalogue decides eligibility, while chat explains the eligible choices.

Make No Match an Honest Answer

An empty result is information. Say that nothing currently matches the product request within the budget. Offer to change the ceiling or another preference, but let the shopper make that choice. Quietly showing a near miss turns a stated constraint into an undisclosed suggestion.

Test the boundary, not just the prose. Place products just below and above a ceiling. Add one product whose variants straddle it and another that is unavailable. Follow every route the assistant uses to search, refine and recommend. Inspect both the retrieved shortlist and the final answer. If either contains an item outside the limit, the conversation has not kept its promise.