## Problem
Search & Discovery filters appear globally across all collections with no built-in way to restrict them to specific collections.
## Cause
Shopify's Search & Discovery app pulls filter values from product data globally — there is no native per-collection filter assignment. However, Shopify automatically hides any filter where none of the products in the current collection have a value for that field.
## Solution
Set metafields only on products that belong to the collection where you want the filters to appear. Products in other collections will have empty metafields, so Shopify hides those filters automatically on those pages — no theme code or third-party app needed.
Example: A store with motorcycle brake hoses in one collection and food-grade hoses in another. Four metafields were created under the `bike` namespace: `bike.brand`, `bike.model`, `bike.year`, and `bike.hose_type`. These were populated only on motorcycle brake hose products via CSV import using the correct column format `Bike Brand (product.metafields.bike.brand)`. Filters were then added in Search & Discovery for all four metafields. Result: the brand, model, year, and hose type filters appear only on the motorcycle brake hose collection page. The food-grade hose collection page shows no bike filters at all, because none of those products have `bike.*` metafield values.
Key detail: the correct Shopify CSV column format for metafields is `Display Name (product.metafields.namespace.key)` — not `Metafield: namespace.key [type]` which is silently ignored by the importer.
## Tools
`shopify_create_metafield_definition`, `shopify_product_metafields`