# Phase 4.2 Implementation Report — Commercial Document Lifecycle & Payment Allocation

**Phase:** 4.2 Commercial Document Lifecycle & Payment Allocation  
**Status:** PASS & VERIFIED  
**Date:** September 4, 2026  
**Role:** Senior Enterprise Architect, Financial Systems Architect, Lead Laravel Engineer  

---

## Executive Summary

Phase 4.2 implements dedicated domain services for managing the lifecycle of customer sales invoices (`InvoiceService`), supplier vendor bills (`SupplierInvoiceService`), customer credit notes (`CreditNoteService`), and settlement allocations (`PaymentAllocationService`).

The accounting boundary established in Phase 4.1 remains 100% intact: zero General Ledger (GL) journals are posted during commercial document state transitions. Multi-tenant isolation (`OrganizationScope` and `BusinessUnitScope`) is enforced across all operations with row locking (`lockForUpdate`) and string-based high-precision decimal calculations (`Decimal(15,4)`).

All 162 existing baseline tests passed without regression, alongside 25 new Phase 4.2 verification tests (totaling 187 tests, 324 assertions, 0 failures, 0 errors).

---

## 1. Pre-Implementation Architecture Assessment

- **What Phase 4.1 Provided:** Database tables (`invoices`, `invoice_lines`, `supplier_invoices`, `supplier_invoice_lines`, `credit_notes`, `credit_note_lines`, `payment_allocations`), domain enums (`InvoiceStatus`, `SupplierInvoiceStatus`, `SupplierInvoiceMatchStatus`, `CreditNoteStatus`), and Eloquent models with global scopes and tenant guards.
- **What Phase 4.2 Added:** Domain services in `app/Domains/Core/Services/` governing document creation, line item calculations, explicit state transitions, invalid transition protections, and transactional payment allocation engines.
- **What Phase 4.2 Excluded:** Zero GL journal postings (`FinancialService::postJournal()`), zero 3-Way Matching Engine overrides (reserved for Phase 4.6), zero business-extension features (no Restaurant, Catering, POS UI, Kitchen, Transport, Water).

---

## 2. Artifacts Created & Modified

### Domain Services (`app/Domains/Core/Services/`)
1. [`InvoiceService.php`](file:///c:/wamp64/www/7/app/Domains/Core/Services/InvoiceService.php):
   - `createDraft(Branch, Customer, ...)`
   - `addLine(Invoice, Item, quantity, unitPrice, TaxCategory, ...)`
   - `removeLine(Invoice, InvoiceLine)`
   - `issueInvoice(Invoice)` — Transitions `DRAFT` → `ISSUED`
   - `cancelInvoice(Invoice)` — Transitions `DRAFT`/`ISSUED` → `CANCELLED` (blocks if payments allocated)
   - `voidInvoice(Invoice, reason)` — Transitions `ISSUED`/`PARTIALLY_PAID` → `VOIDED`
   - `recalculateInvoiceTotals(Invoice)`

2. [`SupplierInvoiceService.php`](file:///c:/wamp64/www/7/app/Domains/Core/Services/SupplierInvoiceService.php):
   - `createDraft(Branch, Supplier, billNumber, internalRef, ...)`
   - `addLine(SupplierInvoice, Item, quantity, unitPrice, TaxCategory, ...)`
   - `removeLine(SupplierInvoice, SupplierInvoiceLine)`
   - `receiveBill(SupplierInvoice)` — Transitions `DRAFT` → `RECEIVED`
   - `approveBill(SupplierInvoice, manager)` — Transitions `DRAFT`/`RECEIVED` → `APPROVED`
   - `voidBill(SupplierInvoice, reason)` — Transitions `DRAFT`/`RECEIVED`/`APPROVED` → `VOIDED`
   - `recalculateBillTotals(SupplierInvoice)`

3. [`CreditNoteService.php`](file:///c:/wamp64/www/7/app/Domains/Core/Services/CreditNoteService.php):
   - `createDraft(Branch, Customer, reason, ...)`
   - `addLine(CreditNote, Item, quantity, unitPrice, TaxCategory, ...)`
   - `removeLine(CreditNote, CreditNoteLine)`
   - `issueCreditNote(CreditNote)` — Transitions `DRAFT` → `ISSUED`
   - `voidCreditNote(CreditNote, reason)` — Transitions `ISSUED` → `VOIDED`
   - `recalculateCreditNoteTotals(CreditNote)`

4. [`PaymentAllocationService.php`](file:///c:/wamp64/www/7/app/Domains/Core/Services/PaymentAllocationService.php):
   - `allocateCustomerPayment(Payment, Invoice, amount, ...)`
   - `allocateSupplierPayment(SupplierPayment, SupplierInvoice, amount, ...)`
   - Transactional pessimistic row locking (`lockForUpdate`)
   - Rejects allocation exceeding payment balance or document balance due
   - Rejects allocation to `DRAFT`, `CANCELLED`, or `VOIDED` documents
   - Updates document `amount_paid`, `balance_due`, and status (`PARTIALLY_PAID` or `PAID`)

### Custom Domain Exceptions (`app/Domains/Core/Exceptions/`)
- [`InvalidStateTransitionException.php`](file:///c:/wamp64/www/7/app/Domains/Core/Exceptions/InvalidStateTransitionException.php)
- [`AllocationException.php`](file:///c:/wamp64/www/7/app/Domains/Core/Exceptions/AllocationException.php)

---

## 3. Lifecycle State Machines & Rules

### Customer Invoice Status Flow
```
[DRAFT] ──► [ISSUED] ──► [PARTIALLY_PAID] ──► [PAID]
   │           │
   └──► [CANCELLED] ──► [VOIDED]
```

### Supplier Invoice Status Flow
```
[DRAFT] ──► [RECEIVED] ──► [APPROVED] ──► [PARTIALLY_PAID] ──► [PAID]
   │             │              │
   └─────────────┴──────────────┴──► [VOIDED]
```

### Credit Note Status Flow
```
[DRAFT] ──► [ISSUED] ──► [APPLIED]
               │
               └──► [VOIDED]
```

---

## 4. Payment Allocation Rules & Transactional Isolation

1. **Monetary Validation:** Allocation amount must be $> 0$.
2. **Payment Balance Boundary:** `amount <= payment.unallocated_amount`.
3. **Document Settlement Boundary:** `amount <= document.balance_due`.
4. **Document Status Guard:** Allocations to `DRAFT`, `CANCELLED`, or `VOIDED` documents are rejected with `AllocationException`.
5. **Tenant Isolation:** Enforces `payment.organization_id == document.organization_id` and `payment.business_unit_id == document.business_unit_id`. Cross-tenant attempts trigger `CrossOrganizationException`.
6. **Concurrency Safety:** Database transaction wraps `Payment::lockForUpdate()` and `Invoice::lockForUpdate()`.

---

## 5. Verification Results

### Test Execution Command
`php artisan test --compact`

### Output Summary
- **Total Tests:** 187
- **Passed:** 187
- **Assertions:** 324
- **Failures:** 0
- **Errors:** 0
- **Skipped:** 0

All 162 baseline tests passed without regression, alongside 25 new Phase 4.2 tests in [`tests/Feature/Core/Phase42CommercialLifecycleTest.php`](file:///c:/wamp64/www/7/tests/Feature/Core/Phase42CommercialLifecycleTest.php).

---

## 6. Deferred Work

- **Automated GL Posting:** Deferred to Phase 4.7 (`InvoiceIssued`, `PaymentAllocated`, `SupplierInvoiceApproved` event listeners).
- **3-Way Matching Engine:** Deferred to Phase 4.6 (`PO` vs `Receipt` vs `Bill` line matching).