SYSTEMS ENGINEERING · ALEXANDER STOKES
Warehouse storage,
from promise to proof.
Can this warehouse accept these pallets for this interval—and can we explain the eventual bill?
A working service, an isolated public lab, and a build guide. Follow one operational story through domain modeling, transactional persistence, API design, interface behavior, and deployment.
THE MODEL
Four concepts. Four different questions.
Capacity
What compatible physical space exists?
Commitment
What space have we promised, and when?
Custody
What goods have we actually accepted?
Billing
What do recorded operations cost under the accepted tariff?
A receipt replaces the matching unfulfilled commitment. A release frees only the goods that departed. An overstay remains physically present even when the next booking expects the space.
THE IMPLEMENTATION GUIDE
Build it in five steps.
Model the promises
Separate capacity, commitment, custody, and billing before choosing tables.
Protect the last position
Make allocation a transaction, then prove two callers cannot both win.
Make retries safe
Treat caller identity, request replay, and invalid transitions as part of the contract.
Expose the operational truth
Make commitments, actual goods, and the resulting invoice independently inspectable.
Ship with evidence
Move an exact source revision through checks, release, and observable health.
DECISIONS YOU CAN INSPECT
Correctness is the feature.
Protect the entire interval
A vacancy check is a query. A capacity promise is a protected write. Allocation, receipt, and amendments use one serialization boundary.
Preserve the facts
Cancelled promises do not erase pallets. Source movements and accepted tariff versions explain charges. Corrections belong in linked records.
Separate the two runtimes
The downloadable reference is Deno + PostgreSQL. The public companion uses the existing Deno + Redis hosting, with independent browser-bound workspaces and atomic saves.
Scope you can trust.
All businesses, inventory, prices, roles, and operational events are synthetic. Ambient pallet storage, two warehouses, a complete request-to-invoice workflow. The public companion is bounded to a 30-minute session; the PostgreSQL reference provides the full standalone service and database tests.
External WMS reconciliation, payments, contractual tariffs, and production warehouse operations remain explicit follow-on work.
Try the decisions.
Start immediately. Your changes and resets affect your own demo workspace. Use the operator and two customer roles to see how the same operation looks from different responsibilities.