System & User Flows

Inventory & Supply Chain

Inventory management spans three tiers: van stock (mobile, carried by each technician), branch warehouse (regional hub), and distributor supply (primary and secondary suppliers). The Inventory Service monitors all tiers in real-time via Redis counters.

Inventory Design Principle: Every technician van is a micro-warehouse. The goal is a 95%+ parts-in-van rate — meaning when a job is dispatched, the required part is already in the technician's van in 95 out of 100 cases, eliminating delays and branch pick-up detours.

Inventory Flow Diagram

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Van Stock Management

Part CategoryMin Van QtyMax Van QtyReplenishment Trigger
Top 20 windshields by market volume2 each4 eachBelow 2 triggers branch request
Side / rear windows (common)1 each2 eachBelow 1 triggers branch request
Side / rear windows (rare makes)0 (order-to-job)1Reserved at branch when job booked
ADAS camera systems0 (order-to-job)1Ordered same-day from OEM/distributor
Urethane (BETASEAL Express)3 cartridges8 cartridgesBelow 3; picked from branch next morning
Primers (auto glass + glass)2 sets5 setsBelow 2 triggers branch request

Automatic Purchase Order (PO) Generation

When branch stock falls below the configured reorder_point for any SKU, the Inventory Service automatically generates a PO:

  1. Inventory Service detects stock level ≤ reorder_point during nightly reconciliation or real-time scan event
  2. Preferred supplier (USG/Pilkington) selected; check if SKU is available and lead time ≤ 2 days
  3. If USG out of stock or lead time > 2 days: automatically route to PGW (secondary)
  4. If both OOS: Ops team alerted; OEM dealer order placed if applicable
  5. PO created in system; EDI 850 purchase order transmitted to supplier
  6. EDI 856 advance ship notice received; stock updated to in-transit status
  7. Barcode-scanned receipt at branch increments qty_on_hand

Part Reservation Logic

  • When a booking is confirmed, Inventory Service reserves the required part (decrements qty_available without touching qty_on_hand)
  • Reservation held for 48 hours; released automatically if booking is cancelled
  • If part is reserved in van: part is locked to that technician's job
  • If part is at branch: van restock route added to technician's morning route
  • If part unavailable anywhere: customer notified with 24-hour delay + 8% discount offered