mapping notes:
  physical item id: No exact Schema.org property identifies one persistent physical object; the ASUI term is intentional.
  offer id: Schema.org identifier may describe an Offer, but ASUI keeps the role explicit to prevent object/listing conflation.
  condition evidence: Schema.org itemCondition does not represent inspection evidence or item-specific notes.
  lifecycle: No Schema.org term expresses the required offer-state transition record.
  alias: No Schema.org term carries the merged-object alias/redirect invariant.
  channel listing: Channel listing identity is an ASUI mapping and never substitutes for physical_item_id.