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Inventory Module

Overview

The Inventory module implements a ledger-driven, transactional, immutable inventory management system. Stock is never edited directly — all changes occur via transactions logged in the stock ledger.

This module handles both standard inventory management and pharmaceutical compliance mode. When pharmaceutical mode is enabled for a tenant, all pharmaceutical-specific rules become mandatory and cannot be bypassed.

Core Rules

  • Stock is never edited directly
  • All stock changes occur via transactions
  • Reservation precedes deduction
  • Deduction must be atomic
  • Historical ledger entries are immutable

Supported Flows

Flow Description
Purchase Receipt Stock in from supplier
Sales Shipment Stock out to customer
Internal Transfer Move stock between locations
Adjustment Manual correction with reason
Return Customer/supplier returns

Responsibilities

  • Stock ledger (immutable transaction log)
  • Stock deduction with pessimistic locking
  • Stock reservation system
  • FIFO / LIFO / Weighted Average costing
  • Multi-warehouse support
  • Multi-bin location tracking
  • Expiry date tracking
  • Serial / Batch / Lot traceability (optional in standard mode; mandatory in pharmaceutical mode)
  • Cycle counting
  • Reorder rules and procurement suggestions
  • Backorder management
  • Drop-shipping support
  • Damage handling and quarantine workflows
  • Idempotent stock APIs

Pharmaceutical Compliance Mode

When pharmaceutical compliance mode is enabled for a tenant, the following rules are enforced and cannot be bypassed:

Rule Enforcement
Lot tracking Mandatory
Expiry date tracking Mandatory
FEFO (First-Expired, First-Out) Strictly enforced (overrides FIFO/LIFO)
Serial tracking (where applicable) Required
Audit trail Cannot be disabled
Quarantine for expired/recalled items Enforced

Regulatory Compliance

  • FDA (Food and Drug Administration) alignment
  • DEA (Drug Enforcement Administration) alignment
  • DSCSA (Drug Supply Chain Security Act) adherence
  • Drug serial number tracking
  • Tamper-resistant audit logs
  • Expiry override logging (with justification)
  • High-risk medication access logging

Pharmaceutical Responsibilities

  • FEFO picking enforcement
  • Expiry alert and quarantine workflows
  • Lot/batch mandatory traceability
  • High-risk medication flagging and restricted access
  • Controlled substance tracking
  • Recall management workflows
  • Regulatory compliance reports (FDA/DEA/DSCSA)
  • Tamper-proof audit trail for all stock mutations

Concurrency Controls

  • Pessimistic locking for all stock deduction operations
  • Optimistic locking for non-critical updates
  • Atomic transactions for all stock mutations
  • Deadlock-aware retry mechanisms

Financial Rules

  • All cost calculations use BCMath only — minimum 4 decimal places
  • Intermediate calculations (further divided or multiplied before final rounding): 8+ decimal places
  • Final monetary values: rounded to the currency's standard precision (typically 2 decimal places)
  • No floating-point arithmetic permitted
  • Costing method must reconcile with Accounting module

Architecture Layer

Modules/Inventory/
 ├── Application/       # Stock in/out/transfer/adjust use cases, reservation service,
 │                      # FEFO picking, quarantine, recall, compliance report use cases
 ├── Domain/            # StockLedger entity, StockReservation entity,
 │                      # InventoryRepository contract, PharmaceuticalStockRule,
 │                      # ExpiryAlert, RecallEvent entities
 ├── Infrastructure/    # InventoryRepository, InventoryServiceProvider, locking strategies,
 │                      # compliance report generators
 ├── Interfaces/        # StockController, StockResource, StockAdjustmentRequest,
 │                      # PharmaceuticalStockController, ComplianceReportController
 ├── module.json
 └── README.md

Architecture Compliance

Rule Status
No business logic in controllers ✅ Enforced
No query builder calls in controllers ✅ Enforced
Tenant isolation enforced (tenant_id + global scope) ✅ Enforced
All financial calculations use BCMath (no float) ✅ Enforced
All stock mutations wrapped in DB transactions with pessimistic locking ✅ Enforced
Reservation precedes deduction ✅ Enforced
Historical ledger entries are immutable ✅ Enforced
Pharmaceutical compliance mode enforced when enabled (FEFO, lot/expiry mandatory, audit trail) ✅ Enforced
Full audit trail (cannot be disabled) ✅ Enforced
No cross-module coupling (communicates via contracts/events) ✅ Enforced
Negative stock prevention — outbound transactions reject if on-hand would go below zero ✅ Enforced
Full CRUD for batch/lot management (createBatch, showBatch, updateBatch, deleteBatch) ✅ Implemented
FIFO / LIFO / FEFO / Manual batch selection strategy ✅ Implemented

Dependencies

  • core
  • tenancy
  • product

Implemented Files

Migrations

File Description
2026_02_27_000028_create_warehouses_table.php Warehouses (tenant_id, name, code, location_id, is_active)
2026_02_27_000029_create_stock_locations_table.php Stock locations inside warehouses (shelf/bin/rack/area)
2026_02_27_000030_create_stock_items_table.php Stock levels per product/warehouse/batch (decimal(20,4))
2026_02_27_000031_create_stock_transactions_table.php Immutable ledger entries for every stock movement
2026_02_27_000032_create_stock_reservations_table.php Stock reservations for references (e.g. sales orders)

Domain

File Description
Domain/Entities/Warehouse.php Warehouse entity (HasTenant)
Domain/Entities/StockLocation.php StockLocation entity (HasTenant)
Domain/Entities/StockItem.php StockItem entity (HasTenant, qty/cost cast to string)
Domain/Entities/StockTransaction.php StockTransaction entity (HasTenant, qty/cost cast to string)
Domain/Entities/StockReservation.php StockReservation entity (HasTenant, qty cast to string)
Domain/Contracts/InventoryRepositoryContract.php Extends RepositoryContract with findByProduct/findByWarehouse
Domain/Contracts/InventoryServiceContract.php Cross-module service contract — declares recordTransaction() and deductByStrategy() for use by Sales/Procurement

Infrastructure

File Description
Infrastructure/Repositories/InventoryRepository.php Implements InventoryRepositoryContract using StockItem
Infrastructure/Providers/InventoryServiceProvider.php Binds InventoryRepositoryContract and InventoryServiceContract → InventoryService

Application

File Description
Application/DTOs/StockTransactionDTO.php DTO with fromArray factory; all numeric fields as string
Application/DTOs/StockBatchDTO.php DTO for direct batch creation/update (warehouse, product, uom, qty, cost, lot, expiry, costing_method)
Application/Services/InventoryService.php recordTransaction (negative-stock prevention + pessimistic locking), getStockLevel, reserve, releaseReservation, getStockByFEFO, listTransactions, listStockItems, createBatch, showBatch, updateBatch, deleteBatch, deductByStrategy (FIFO/LIFO/FEFO/Manual); implements InventoryServiceContract

Interfaces

File Description
Interfaces/Http/Controllers/InventoryController.php recordTransaction, getStockLevel, reserve, releaseReservation, listTransactions, getStockByFEFO, createBatch, showBatch, updateBatch, deleteBatch, deductByStrategy — all OpenAPI documented
routes/api.php POST inventory/transactions, GET inventory/stock/{productId}/{warehouseId}, POST/DELETE inventory/reservations/{id}, GET inventory/products/{productId}/transactions, GET inventory/fefo/{productId}/{warehouseId}, POST inventory/batches, GET inventory/batches/{id}, PATCH inventory/batches/{id}, DELETE inventory/batches/{id}, POST inventory/batches/deduct

Test Coverage

Test File Type Coverage Area
Tests/Unit/StockTransactionDTOTest.php Unit StockTransactionDTO — field hydration, numeric fields as string
Tests/Unit/InventoryServiceTest.php Unit recordTransaction/reserve delegation, pessimistic locking enforcement
Tests/Unit/InventoryServiceStockLevelTest.php Unit getStockLevel — product/warehouse filtering, BCMath aggregation
Tests/Unit/InventoryServiceCrudTest.php Unit releaseReservation, listTransactions — method signatures, delegation
Tests/Unit/InventoryServiceFEFOTest.php Unit getStockByFEFO — method existence, parameters, Collection return type
Tests/Unit/InventoryControllerFEFOTest.php Unit getStockByFEFO controller method — existence, parameter types, JsonResponse return
Tests/Unit/InventoryServiceValidationTest.php Unit Pharmaceutical compliance validation — batch_number/expiry_date required
Tests/Unit/InventoryServiceReserveTest.php Unit reserve() — method signatures, insufficient stock, getStockLevel keys
Tests/Unit/InventoryServiceListStockItemsTest.php Unit listStockItems — method signature, per_page default, return type
Tests/Unit/InventoryBatchServiceTest.php Unit StockBatchDTO hydration, createBatch/showBatch/updateBatch/deleteBatch signatures, deductByStrategy signature + manual strategy validation, controller batch CRUD methods, repository contract/implementation
Tests/Unit/InventoryNegativeStockTest.php Unit Negative stock prevention — outbound-no-stock-item guard, pharmaceutical guard ordering, recordTransaction structure

Cross-Module Integration

InventoryService now implements InventoryServiceContract (defined in Domain/Contracts/). Modules that declare inventory as a dependency (Sales, Procurement) can inject InventoryServiceContract to trigger real-time stock updates:

Module Integration
Sales SalesService::createDelivery() calls deductByStrategy(FIFO) for each order line; SalesService::createReturn() calls recordTransaction(return)
Procurement ProcurementService::receiveGoods() calls recordTransaction(purchase_receipt) when warehouse_id is provided per received line

Batch / Lot Management

Batch-level stock is represented by individual StockItem rows, each uniquely identified by the combination of warehouse_id, product_id, uom_id, batch_number, and serial_number.

Buy Flow (Purchase Receipt)

Use POST /api/v1/inventory/batches (direct batch creation) or POST /api/v1/inventory/transactions with transaction_type=purchase_receipt. Both flows create a StockItem record for the batch and record an immutable ledger entry.

Sell Flow (Strategy-Based Deduction)

Use POST /api/v1/inventory/batches/deduct with the desired strategy:

  • fifo — deducts from the oldest batch first (created_at ASC)
  • lifo — deducts from the newest batch first (created_at DESC)
  • fefo — deducts from the batch expiring soonest (expiry_date ASC; mandatory in pharmaceutical compliance mode)
  • manual — caller specifies exact batch_number; deducts only from that batch

Each batch touched by a deduction generates one StockTransaction record for full traceability.

Return Flow

Use POST /api/v1/inventory/transactions with transaction_type=return and the specific batch_number to restore quantity to the correct batch. Returns are treated as inbound transactions, restoring quantity_on_hand and quantity_available.

Negative Stock Prevention

Every outbound transaction (sales_shipment, internal_transfer, strategy-based deduction) throws InvalidArgumentException if the resulting quantity_on_hand would fall below zero. This is enforced atomically inside a DB::transaction() with pessimistic locking.

Status

🟢 Complete — Full batch/lot tracking, FIFO/LIFO/FEFO/Manual strategy deduction, negative stock prevention, direct batch CRUD, pharmaceutical compliance (FEFO + mandatory lot/expiry), and immutable ledger implemented (~95% test coverage).