Track partial consumption / sub-unit inventory for multi-pack items #12

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opened 2026-04-02 21:54:31 -07:00 by pyr0ball · 0 comments

pyr0ball commented

2026-04-02 21:54:31 -07:00

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Problem

When a product is scanned as a multi-pack (e.g. a 4-stick pack of butter, a 6-pack of yoghurt), the inventory item has quantity=1 and unit=pack. There is no way to track that 1 of 4 sticks has been used.

Desired Behaviour

Scan flow: Auto-detect pack size from product data (Open Food Facts serving_size / unit_count) and pre-fill quantity accordingly (e.g. quantity=4, unit=stick)
Recipe use: When a recipe is cooked, offer to decrement specific ingredient quantities from inventory rather than marking entire items as consumed
Partial consume endpoint: POST /inventory/items/{id}/consume should accept an optional quantity param (default: consume all)

Acceptance Criteria

scanBarcodeText / scanBarcodeImage pre-fills sub-unit quantity when product data includes it
POST /inventory/items/{id}/consume?quantity=1 decrements by that amount; only marks status=consumed when quantity reaches 0
UI shows remaining quantity on inventory cards
Recipe suggestion view offers "Mark ingredients as used" which decrements each matched pantry item by a reasonable serving amount

Notes

inventory_items.quantity and inventory_items.unit already exist in the schema
Serving-size data quality from Open Food Facts is variable — fall back to quantity=1 when not available

## Problem When a product is scanned as a multi-pack (e.g. a 4-stick pack of butter, a 6-pack of yoghurt), the inventory item has `quantity=1` and `unit=pack`. There is no way to track that 1 of 4 sticks has been used. ## Desired Behaviour - **Scan flow:** Auto-detect pack size from product data (Open Food Facts serving_size / unit_count) and pre-fill quantity accordingly (e.g. quantity=4, unit=stick) - **Recipe use:** When a recipe is cooked, offer to decrement specific ingredient quantities from inventory rather than marking entire items as consumed - **Partial consume endpoint:** `POST /inventory/items/{id}/consume` should accept an optional `quantity` param (default: consume all) ## Acceptance Criteria - [ ] `scanBarcodeText` / `scanBarcodeImage` pre-fills sub-unit quantity when product data includes it - [ ] `POST /inventory/items/{id}/consume?quantity=1` decrements by that amount; only marks `status=consumed` when quantity reaches 0 - [ ] UI shows remaining quantity on inventory cards - [ ] Recipe suggestion view offers "Mark ingredients as used" which decrements each matched pantry item by a reasonable serving amount ## Notes - `inventory_items.quantity` and `inventory_items.unit` already exist in the schema - Serving-size data quality from Open Food Facts is variable — fall back to quantity=1 when not available