Design fulfillment truck routing and inventory system

Scenario

You are designing software for a large e-commerce fulfillment center to plan truck routes and manage containers/inventory movement within and across facilities.

The system must support:

• Inbound trucks delivering pallets/containers to a fulfillment center.
• Outbound trucks picking up containers for delivery to other facilities or last-mile hubs.
• Containers (e.g., totes/pallets) that hold inventory items and move between dock doors , staging areas , and storage locations .

Functional Requirements (FR)

1. Create and manage shipments : inbound/outbound loads with a list of containers and planned arrival/departure windows.
2. Assign trucks to dock doors and time slots; detect and resolve conflicts.
3. Route planning :
   • Given a set of stops (facilities/docks) and time windows, produce a feasible route/sequence.
   • Support re-planning when conditions change (delays, cancellations).
4. Track container state end-to-end:
   • Container location (facility + zone), status (created, staged, loaded, in-transit, received), and contents summary.
5. Inventory correctness :
   • Prevent double-allocation of a container/inventory.
   • Reconcile when scans disagree or events arrive late/out of order.
6. APIs/UI : dispatchers can view routes, door schedule, and container statuses; operators can scan containers.

Non-Functional Requirements (NFR)

• High availability for operational workflows (door assignment, scan updates).
• Low-latency updates for scan events (near real-time).
• Auditability: full history of container movements and changes.
• Multi-warehouse support; permissions/access control.

Constraints / Assumptions (you can state reasonable ones)

• Many scan events per minute; multiple facilities.
• Network partitions can happen; scan devices may buffer events.

Deliverables

Design:

• High-level architecture (services, data stores, messaging).
• Core data model (key entities and relationships).
• Key APIs/events.
• Consistency strategy (idempotency, ordering, deduplication).
• Routing/optimization approach (exact vs heuristic) and what you optimize for.
• Observability and failure handling.