Case study · 2026
Dynamic Inventory Reservation Engine
Exact said stock existed; the warehouse had already committed it to another order.
- Exact Online
- Node.js
- Shopify App
- Database
- Discipline
- Inventory allocation · Exact Online · Warehouse logic
- Year
- 2026
- Engagement
- Fixed scope
- Status
- Live
01Context
- Detect inventory reserved by Mondial orders.
- Subtract reserved quantities from Exact shelf stock.
- Recalculate all affected open orders by SKU.
Exact Online deducts stock when an order physically ships. During picking and packing, inventory can therefore still appear available even though warehouse staff have effectively reserved it.
Weldaad marks orders ready for picking with a specific selection code, “Mondial.” Those quantities needed to reduce availability for every other open order immediately.
HeapByte extended the existing Exact integration with a reservation layer that calculates actual pickable inventory.
02What was in the way
- 01
Stock timing mismatch
ERP inventory and warehouse operational reality update at different moments.
- 02
Cross-order effects
Reserving one SKU for one order can change the fulfillment status of many unrelated orders.
- 03
Avoiding double deductions
Once an order ships, Exact itself deducts inventory, so the temporary reservation must disappear.
03Architecture
What we built, and what we deliberately left alone.
- 01
SKU reservation map
Quantities from active Mondial orders are aggregated by SKU.
- 02
Derived available stock
Operational availability is calculated independently from raw Exact stock.
- 03
Existing rules preserved
The downstream order-classification system continues using the same logic but receives a more accurate stock input.
Delivery
- Reservation model
- Mondial detection
- SKU aggregation
- Cross-order recalculation
- Production testing
04Outcome
- Availability formula
- Exact − Mondial
- Recalculation
- Cross-order
- Existing dashboard
- Preserved
Pickable inventory replaces raw shelf stock
Shared SKUs update across active orders
No parallel inventory system required
05Engineering notes
- Reservation aggregation
- Open Mondial order lines are grouped by SKU before downstream calculations.
- Availability layer
- Derived inventory feeds order calculations without modifying Exact's own accounting stock.
- Release behavior
- When shipment completes, the temporary Mondial reservation leaves the calculation while Exact performs the real stock deduction.
- Customer indicators
- The same operational application later added persistent customer star/flag controls for fulfillment context.
What we took from it
- 01ERP stock and operationally available stock are different concepts.
- 02Reservations should modify availability, not physical inventory.
- 03Shared SKU recalculation needs centralized logic.
- 04Shipment release is as important as reservation creation.
Disciplines applied
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