Instance

An Instance is a specific physical or logical thing Stockaj tracks: a serialized unit, a lot of consumables, a logistic unit (pallet), or a bulk bucket of untracked stock.

Field	Type	Notes
id	integer	Stockaj internal id
product_id	integer	Reference to the product template
kind	enum	SERIAL, LOT, SSCC, BULK
epc	string	Pure Identity URI
serial	string	For SERIAL (GS1 AI 21)
lot	string	For LOT (GS1 AI 10)
produced_at	date	AI 11
expires_at	date	AI 17
best_before_at	date	AI 15
current_location_id	integer	Projection — read-only via API
current_disposition	string	CBV disposition URI — projection
current_owning_party_id	integer	Projection
current_qty	number	For BULK only
ilmd	object	Per-instance master data (matches product's ilmd_schema)

EPC formats by kind

Kind	EPC URI
SERIAL	urn:epc:id:sgtin:<gcp>.<itemref>.<serial>
LOT	urn:epc:idpat:sgtin:<gcp>.<itemref>.* + lot field
SSCC	urn:epc:id:sscc:<gcp>.<extension>
BULK	(no EPC; aggregated by (product, location) key)

Projections (read-only)

current_* fields are projections computed from the EPCIS event log. The API exposes them for fast reads, but they cannot be written directly — the only way to change an instance's state is to record a new event.