Fictional worked example
What can we promise?
A small tool that keeps stock on the shelf separate from stock someone hopes will arrive.
This is a constructed example, not a client result or a completed team trial. The numbers below are fictional. The calculator runs locally in your browser and has no connection to inventory systems.
The first useful result
User: a customer service lead answering a 100-unit order. Decision: how much to promise by the requested date. Today, the lead compares a warehouse export, reservations, and an inbound list by hand.
Acceptance rule: do not count reserved stock twice or treat an unconfirmed arrival as available. Show the immediate quantity, the quantity eligible by the promise date, and the remaining shortfall.
| Source | Input | Coverage and limitation |
|---|---|---|
| Warehouse snapshot | 80 sellable units | Physical stock at this warehouse only; excludes damaged stock. |
| Reservations | 30 units committed elsewhere | Same snapshot and SKU; excludes this new order. |
| Inbound list | 50 units, arrival unconfirmed | Not counted until confirmed available for dispatch by the promise date. |
| Customer request | 100 units by October 9 | A dispatch promise, not a delivery guarantee. |
Try the working output
These are editable demonstration inputs. The confirmation checkbox changes an assumption in this example; it does not confirm a real shipment.
Promise 50 of the 100 units.
Available now: 80 − 30 = 50. Eligible inbound: 0. Shortfall: 50.
Offer a split order or obtain a confirmed inbound date before promising the balance.
Rule: available now = stock − reservations. Eligible inbound = confirmed inbound, otherwise zero. Promise quantity = the smaller of the order and available now plus eligible inbound. This does not check freight, warehouse capacity, credit, or other SKUs.
Expected checks
| Case | Expected output |
|---|---|
| 80 stock, 30 reserved, 50 unconfirmed inbound, order 100 | 50 now; promise 50; shortfall 50. |
| Same inputs, inbound confirmed by the promise date | 50 now; promise 100 by that date; shortfall 0. Do not say all 100 are on hand. |
| Order 20, original stock and reservations | Promise 20; shortfall 0. |
| Blank, negative, fractional, or unsafe large number | Stop and identify invalid input; never substitute zero. |
| Reservations greater than stock | Stop and reconcile the conflicting source snapshots. |
Hand it to the next person
Built: this local calculator. Its source files are shipping-example.js, this HTML page, and the linked styles. Checked scope: arithmetic and validation for the fictional cases above. No live inventory reconciliation or customer promise has occurred.
Open human trial: ask a teammate to answer the original order, then the confirmed-arrival version, without coaching. They should explain why “available now” differs from “promise by Friday.” Record any mistake or missing instruction.
Proposed operating handoff: the customer service lead owns the answer; warehouse and purchasing owners confirm the source snapshots. Refresh before each real promise. Stop if dates, SKU, commitments, or units do not match. A real deployment needs live-source checks and an agreed freshness rule before anyone relies on it.