> ## Documentation Index > Fetch the complete documentation index at: https://docs.arcuserp.com/llms.txt > Use this file to discover all available pages before exploring further. # A purchase order's landed costs > Every landed allocation that reached this purchase order's receipts, with its inventory and COGS share, and per line the goods cost, landed cost and landed unit cost. It reveals inventory cost and cost of goods sold, so it requires the margin permission; no API scope grants it today, so an API key is refused 403 margin_permission_required (the same answer as a user without the permission). ## OpenAPI ````yaml /openapi.yaml get /purchase-orders/{id}/landed-costs openapi: 3.1.0 info: title: Arcus ERP Public API version: 1.0.0 description: > Arcus ERP public REST API. Designed for external integrations and data migration. **Authentication.** Bearer token (API key) via the `Authorization` header. Format: `Authorization: Bearer ark_live_ent__` (or `ark_test_*` for sandbox). API keys are issued per-entity in **Settings > Developers > API Keys**. **Entity scoping.** The entity is encoded in the API key prefix; routes are flat (e.g. `/v1/accounts`, `/v1/orders`, `/v1/products`). A small set of platform endpoints (migration, reconciliation, events, webhook endpoints, API keys) use the `/v1/entities/{entity_id}/...` form -- those are noted in their tags. **Key capabilities.** - Related-resource hydration via `?expand[]=` (see `x-arcus-expand` on each resource). - Cursor-based pagination (`starting_after` / `ending_before` / `limit`). - Idempotency via the `Idempotency-Key` header. - Webhook events for asynchronous notification. - Conditional requests / ETag for cache validation. **Changelog.** Entries are dated and name every published contract whose MEANING moved, not only the ones whose field names changed. The narrative version of the same entries, written for integrators, is published at https://arcuserp.mintlify.app/changelog. **2026-09-22 (planned 2026-09-21), REORDER-BUYER-TRUTH: demand changed what it MEANS on three published contracts, with no field renamed.** An integrator that pins field names sees no breakage and different numbers, which is why this entry exists. - **Demand now counts build consumption.** `demand_avg_per_day` on the public product, kit and inventory-balance objects, and `daily_demand` / `demand_basis` / `net_suggested_qty` on `GET /v1/purchasing/reorder-report`, are composed from fulfilled sales lines PLUS posted `build_consume` inventory draws: each physical decrement of a product counts exactly once. The previous rule adopted an internal-consumption basis only when the sales blend was exactly zero, so a product both sold AND consumed into work orders planned as if the build draws did not exist. Products drawn into work orders move; on one production-shaped dataset five did, the largest from 0.05/day to 14.95/day. - **`demand_basis` now carries four values, not two:** `sales`, `sales_and_builds`, `builds` and `consumption`. A consumer with a two-branch reader (anything that is not `consumption` is `sales`) silently hides the two new ones. - **`current_demand_units` on `GET /v1/inventory/balances/:id` moved, by a second rule.** It counts committed-but-unshipped CUSTOMER demand, and it now counts a kit component's own line rather than its parent kit line, and excludes non-sales documents. On one production dataset 269 of 1,043 balance rows changed, 227 of them downward; the largest single move was 1,941 to 25, on a product whose open PURCHASE order line had been reported as customer demand. Re-baseline anything that alerts or reorders off this field. - `run_rate_30/90/180/365` and `blended_daily` on the same balance object move for the first reason above. - **Added, not changed:** `GET /v1/purchasing/reorder-report` accepts `demand_window` and returns the unit, cover-through and reorder-point-provenance fields documented on that operation; `order_multiple` is accepted and returned on the product-vendor doors. - **Volume note.** The `inventory.low_stock`, `inventory.out_of_stock` and `inventory.back_in_stock` webhook events are population-gated on `on_hand <= reorder_point`, and reorder points move with the demand above, so subscribers should expect a one-time step change in event volume around the release. servers: - url: https://api.arcuserp.com/v1 description: Arcus ERP API (accepts both live `ark_live_*` and test `ark_test_*` keys) - url: https://dev-api.arcuserp.com/v1 description: >- Dev sandbox API (test-only data, accepts `ark_test_*` keys against dev RDS) security: [] paths: /purchase-orders/{id}/landed-costs: parameters: - name: id in: path required: true schema: type: string format: uuid get: tags: - Purchasing summary: A purchase order's landed costs description: >- Every landed allocation that reached this purchase order's receipts, with its inventory and COGS share, and per line the goods cost, landed cost and landed unit cost. It reveals inventory cost and cost of goods sold, so it requires the margin permission; no API scope grants it today, so an API key is refused 403 margin_permission_required (the same answer as a user without the permission). operationId: getPurchaseOrderLandedCostsV1 responses: '200': description: The purchase order's landed costs. content: application/json: schema: type: object properties: data: $ref: '#/components/schemas/PurchaseOrderLandedCosts' '400': $ref: '#/components/responses/Error' '401': $ref: '#/components/responses/Error' '403': $ref: '#/components/responses/Error' '404': $ref: '#/components/responses/Error' security: - ApiKeyAuth: [] components: schemas: PurchaseOrderLandedCosts: type: object description: >- A purchase order's landed costs (DESIGN D13): every landed allocation that reached its receipts (Case A, a landed-only bill naming the PO, a receipt-set bill on its receipts), each with its inventory share (what the layer and the layers its bump was followed into still hold now) and its COGS share (the rest), from the same plan a void runs; per PO line the units, goods cost at receipt, landed cost and landed unit cost; the landed bills; and the totals by category. Margin-grade throughout. properties: po_id: type: string format: uuid po_number: type: string allocations: type: array items: type: object properties: allocation_id: type: string format: uuid bill_id: type: string format: uuid bill_number: type: string bill_status: type: string vendor_id: type: string format: uuid vendor_name: type: string nullable: true category: type: string nullable: true basis: type: string nullable: true product_id: type: string format: uuid product_title: type: string nullable: true sku: type: string nullable: true location_id: type: string format: uuid nullable: true location_name: type: string nullable: true order_item_id: type: string format: uuid nullable: true receiving_transaction_id: type: string format: uuid nullable: true purchase_receipt_item_id: type: string format: uuid nullable: true receipt_reference: type: string nullable: true target: type: string enum: - layer - drop_ship description: >- layer, or drop_ship (a drop-ship receipt line: fifo_layer_id null, purchase_receipt_item_id set, inventory share 0). fifo_layer_id: type: string format: uuid nullable: true date: type: string format: date amount: type: number inventory_share: type: number cogs_share: type: number reversal_refusal: type: string nullable: true description: The code a void of this bill would answer now if any.: null lines: type: array items: type: object properties: order_item_id: type: string format: uuid product_id: type: string format: uuid nullable: true product_title: type: string nullable: true sku: type: string nullable: true quantity_ordered: type: number quantity_received: type: number po_unit_cost: type: number nullable: true goods_cost: type: number landed_cost: type: number goods_unit_cost: type: number nullable: true landed_cost_per_unit: type: number nullable: true landed_unit_cost: type: number nullable: true landed_bills: type: array items: $ref: '#/components/schemas/PurchaseOrderLandedBill' totals: type: object properties: goods_cost: type: number landed_cost: type: number inventory_share: type: number cogs_share: type: number unattributed_landed_cost: type: number by_category: type: array items: type: object properties: category: type: string amount: type: number PurchaseOrderLandedBill: type: object description: >- A landed bill that reaches a purchase order. Identity only on the purchase order itself; allocated_on_this_po only inside PurchaseOrderLandedCosts. properties: bill_id: type: string format: uuid bill_number: type: string vendor_id: type: string format: uuid vendor_name: type: string nullable: true bill_date: type: string format: date status: type: string mode: type: string enum: - case_a - po_landed - receipt_set description: >- case_a (goods and landed lines on a bill naming the PO), po_landed (a landed-only bill naming the PO) or receipt_set (a Case-B bill on this PO's receipts). categories: type: array items: type: string allocated_on_this_po: type: number description: Inside PurchaseOrderLandedCosts only. ErrorEnvelope: type: object description: | Canonical error response envelope. All API errors use this shape. required: - error - code properties: error: type: string description: Machine-readable error key example: not_found code: type: string description: Machine-readable error code (often same as error) example: not_found type: type: string enum: - validation_error - permission_error - not_found - conflict - rate_limit - internal - expand_error - not_implemented example: not_found hint: type: string description: Human-readable one-sentence explanation (English) example: >- The requested order does not exist or does not belong to this entity. param: type: string description: The parameter that caused the error, if applicable example: expand[0] required: type: string description: The scope required (only on insufficient_scope errors) example: accounts:read request_id: type: string description: >- Unique request ID for support tracing (maps to CloudWatch log stream) example: req_abc123 responses: Error: description: Error response (400/401/403/404/409/422/429/500) content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' securitySchemes: ApiKeyAuth: type: http scheme: bearer description: | API key issued per entity via Settings > Developers > API Keys. Each key carries scopes (e.g. orders:read, products:write). Bearer token format: Authorization: Bearer ark_live_ent__ Test keys use ark_test_ent__. Both are issued per entity via Settings > Developers > API Keys. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.