List Catalog Items

Lists catalog items for the authenticated merchant, including current HSA/FSA eligibility for each item. This endpoint is intended to complement the `Item Eligibility Updated` webhook: use the webhook to receive ongoing updates, and use this endpoint to enumerate items that were already categorized before webhook ingestion began (or to reconcile after a gap). Use `eligibility` to scope the response to a specific eligibility state, and `updated_after` to incrementally sync only items changed since the last poll. ### Computing the HSA/FSA-eligible amount Items eligible only for the margin over an everyday equivalent carry that equivalent's price as `comparable_item_price_cents`: ``` eligible_amount = max(0, unit_price - comparable_item_price_cents) * quantity ``` It is absent when the full price is eligible, and when the item cannot be charged to an HSA/FSA card. ### Keeping `comparable_item_price_cents` current Truemed reviews these prices about monthly. A change fires no webhook and does not advance `updated_at`, so re-read the catalog in full at least monthly. The charged amount is settled at checkout.