# README

## Overview

The Purchase module manages the procurement lifecycle from supplier-facing commercial terms through purchase ordering, receipt confirmation, and supplier bill matching. It owns the transactional records that express what was ordered from which supplier, at what price, under which payment terms, for which receiving site, and how much of that commitment has been received or invoiced.

Purchase sits between master-data modules and operational/financial execution modules. It references suppliers from business-partner, items from item-management, organizational scope from organization, and currencies/UoMs from primitives. It also coordinates with inventory for inbound stock receipt execution and with future accounting or accounts-payable modules for financial posting, while keeping commercial procurement rules inside the purchase domain. Role-based access control and auditable state transitions are treated as first-class requirements via user-management and audit integrations.

## Key Features

- **[Purchase Requisition Lifecycle](docs/feature/purchase-requisition-lifecycle.md)**: Create and manage PurchaseRequisition documents with line items, estimated costs, requester and department context, and an approval lifecycle from draft through submission, approval, conversion to purchase order, or cancellation
- **[Purchase Requisition to PO Conversion](docs/feature/purchase-requisition-to-po-conversion.md)**: Convert approved purchase requisition lines into draft purchase orders with supplier resolution, pricing defaulting, payment term inheritance, and full line-level traceability
- **[Purchase Order Lifecycle](docs/feature/purchase-order-lifecycle.md)**: Create and manage PurchaseOrder documents with line items, supplier references, expected delivery dates, lifecycle control, and fulfillment status tracking from draft through inventory receipt evidence and billing completion
- **[Supplier Purchase Pricing](docs/feature/supplier-purchase-pricing.md)**: Maintain supplier-specific purchase price lists and rules with date validity, quantity breaks, currency support, and deterministic defaulting onto purchase order lines
- **[Purchase Payment Terms](docs/feature/purchase-payment-terms.md)**: Define supplier-facing payment schedules and installment structures that flow from ordering into supplier bill due-date calculation
- **[Supplier Bill Matching](docs/feature/supplier-bill-matching.md)**: Capture supplier invoices as PurchaseBill documents, validate them using 2-way or 3-way matching rules, detect quantity/price variances, and hand matched bills to downstream accounts-payable processing

## Module Scope

### In Scope

- Purchase requisition creation, submission, approval, rejection back to draft, recall, cancellation, conversion to purchase order, and closure
- Purchase requisition lines with item or free-text description, requested quantity, estimated unit price, optional suggested supplier, and need-by date
- Conversion of approved purchase requisition lines into draft purchase orders with supplier resolution, pricing defaulting, payment term inheritance, and line-level traceability
- Purchase order creation, revision, approval or ordering, rejection back to draft, cancellation, closure, and fulfillment status tracking
- Purchase order lines with item, quantity, unit of measure, supplier price, currency, expected delivery date, and receiving or billing progress
- Supplier-specific purchase pricing via `PurchasePriceList` and `PurchasePriceRule`, including effective dates, quantity breaks, and rule selection precedence
- Supplier-facing payment term definitions via `PurchasePaymentTerm`, including fixed-day, net-day, and installment schedules
- Receipt progress tracking from inventory-owned `GOODS_RECEIPT` execution evidence, including partial receipts and received-quantity accumulation against purchase order lines
- Supplier bill capture and matching via `PurchaseBill`, including duplicate invoice detection, 2-way or 3-way matching, quantity or price variance handling, tax snapshot capture, and pre-match cancellation controls
- Integration with inventory for inbound stock execution and receipt evidence, plus downstream accounting/AP handoff readiness for matched supplier bills
- Company-scoped procurement documents with supplier references restricted to ACTIVE suppliers carrying the SUPPLIER role

### Out of Scope

- Supplier onboarding, qualification, certification, and performance scoring (business-partner or future supplier-management workflows)
- Approval matrix orchestration, multi-level approval chains, RFQ or tendering, and sourcing auctions (future supplier-portal module or application layer)
- Blanket orders, call-off contracts, and framework agreements with committed release quantities (future purchasing enhancement)
- Reorder point planning, MRP-driven replenishment, and demand forecasting (future planning module)
- Warehouse execution details such as putaway, bin-level receiving tasks, storage assignment, and stock valuation calculation (inventory module)
- Landed cost allocation, customs or duty accruals, and freight capitalization (future purchasing/accounting capability)
- Tax determination, journal entry posting, accounts payable payment execution, and bank settlement (future accounting or AP modules)
- Supplier returns and return-to-vendor logistics (future reverse-logistics or extended purchase capability)
- Supplier catalog content syndication and punchout integration (future application-layer integration)

### Scope Decision Rationale

Purchase is scoped to the **commercial procurement document flow**: negotiated supplier price, agreed payment terms, order commitment, receipt progress, and supplier invoice matching. Those artifacts change together and depend on the same business rules, so they belong in one module rather than being split prematurely across pricing or AP domains.

Inventory is intentionally kept as the owner of **physical stock state, receipt execution, and valuation execution**. Purchase records supplier commitments and derives receipt progress from inventory evidence; inventory owns stock movement, on-hand balance, lot or serial handling, and cost layer updates. This separation keeps procurement focused on supplier-side matching rather than warehouse internals.

Financial settlement is also kept out of scope. Purchase can determine whether a supplier bill is commercially valid and ready to pay, but journal posting, tax treatment, and cash disbursement belong to downstream accounting or AP modules. This preserves a clean contract: purchase validates the obligation; accounting recognizes and settles it.

Supplier-specific pricing and payment terms are included here because they directly drive purchase order and bill behavior. Although generic enterprise pricing might later move into a dedicated cross-domain pricing module, the initial supplier-facing rules are tightly coupled to procurement and are needed to make purchase orders and bill matching useful from day one.

The purchase module also owns the minimum cross-module contracts needed for execution. Inventory-owned goods receipt executions provide the receipt evidence used for purchase status and 3-way bill matching. Supplier bills remain inside purchase until matching completes; only then may a downstream AP/accounting handoff accept the bill for posting or settlement. Once that downstream handoff is accepted, cancellation or credit processing is no longer a pure purchase concern.

## Module Dependencies

- [business-partner](../business-partner/README.md) — Supplier reference, contact, address, and role classification; only ACTIVE partners with the SUPPLIER role can be used in purchase transactions
- [item-management](../item-management/README.md) — Item/SKU references on purchase order, receipt, and bill lines
- [organization](../organization/README.md) — Company scoping and receiving or delivery site context for purchase documents
- [primitives](../primitives/README.md) — Currency and unit-of-measure references for pricing, quantities, and payment term calculations
- [inventory](../inventory/README.md) — Downstream execution of inbound stock movements and warehouse-level receipt consequences
- [user-management](../user-management/README.md) — Procurement, receiving, and AP-facing permissions for submit, approve, receive, match, release, and cancel actions
- [audit](../audit/README.md) — Immutable audit trail for order, receipt, and bill state transitions and comparison outcomes
- [coa-management](../coa-management/README.md) — Future integration target for payable, accrual, and variance account references once accounting posting is introduced
