> ## 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. # Receive inventory (non-PO) -- single or multi-item atomic > ATOMIC-CREATE (2026-05-12): accepts items[] for multi-line atomic receipts OR top-level product_id/quantity/unit_cost for single-item compat mode. All items receive in one DB transaction; any failure rolls back all items. Hard-blocks zero-cost (unit_cost must be > 0 per item). GL: DR Inventory / CR GRNI via postInventoryReceived, fires per item in same transaction (Rule 21). Connector: triggers async pushInventoryToMarketplaces (Shopify/Amazon/eBay). For PO-linked receipts: POST /v1/purchase-orders/{id}/receive. Response: {object:inventory_receive_result, items:[{balance,transaction}], summary} for items[]; single object for compat mode. ## OpenAPI ````yaml /openapi.yaml post /inventory/receive 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. 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: /inventory/receive: post: tags: - Inventory summary: Receive inventory (non-PO) -- single or multi-item atomic description: > ATOMIC-CREATE (2026-05-12): accepts items[] for multi-line atomic receipts OR top-level product_id/quantity/unit_cost for single-item compat mode. All items receive in one DB transaction; any failure rolls back all items. Hard-blocks zero-cost (unit_cost must be > 0 per item). GL: DR Inventory / CR GRNI via postInventoryReceived, fires per item in same transaction (Rule 21). Connector: triggers async pushInventoryToMarketplaces (Shopify/Amazon/eBay). For PO-linked receipts: POST /v1/purchase-orders/{id}/receive. Response: {object:inventory_receive_result, items:[{balance,transaction}], summary} for items[]; single object for compat mode. operationId: postInventoryReceive parameters: - $ref: '#/components/parameters/IdempotencyKey' requestBody: required: true content: application/json: schema: oneOf: - type: object description: Multi-item atomic mode required: - location_id - items properties: location_id: type: string format: uuid description: Layer 4 -- required notes: type: string items: type: array minItems: 1 items: type: object required: - product_id - quantity - unit_cost properties: product_id: type: string format: uuid quantity: type: integer minimum: 1 unit_cost: type: number description: Must be > 0 notes: type: string - type: object description: Single-item compat mode required: - product_id - location_id - quantity - unit_cost properties: product_id: type: string format: uuid location_id: type: string format: uuid description: Layer 4 -- required quantity: type: integer minimum: 1 unit_cost: type: number description: Required, must be > 0 notes: type: string examples: multi_item: summary: Multi-item atomic receive (2 SKUs, one transaction) value: location_id: 91aa7588-4dc7-4edd-b172-7de91f5e1f78 notes: Restocking run from supplier items: - product_id: 7f6f3e14-eaad-4c45-b922-209f6dc6d140 quantity: 10 unit_cost: 12.5 notes: Circuit Breaker 10A White - product_id: ec9288c3-12b1-474f-bb09-b0b15bb7a8ff quantity: 5 unit_cost: 8.75 notes: Square D Breaker Black single_item: summary: Single-item compat mode value: product_id: 7f6f3e14-eaad-4c45-b922-209f6dc6d140 location_id: 91aa7588-4dc7-4edd-b172-7de91f5e1f78 quantity: 25 unit_cost: 12.5 notes: Emergency restock responses: '201': description: Inventory received content: application/json: schema: type: object properties: object: type: string enum: - inventory_receive_result examples: multi_item_result: summary: Multi-item receive result value: object: inventory_receive_result items: - index: 0 product_id: 7f6f3e14-eaad-4c45-b922-209f6dc6d140 location_id: 91aa7588-4dc7-4edd-b172-7de91f5e1f78 quantity: 10 unit_cost: 12.5 balance: id: 0118ff93-8f65-4a72-ae7e-ca2a75526631 on_hand: 10 allocated: 0 available: 10 total_value: '125.00' avg_unit_value: '12.5000' transaction: id: 3096987e-b156-4ee0-b373-8056f5bd8d91 type: receiving quantity: 10 unit_price: '12.5000' total_price: '125.00' transaction_id: IVT-0000153 - index: 1 product_id: ec9288c3-12b1-474f-bb09-b0b15bb7a8ff location_id: 91aa7588-4dc7-4edd-b172-7de91f5e1f78 quantity: 5 unit_cost: 8.75 balance: id: 6e082a9d-7314-4bd9-9bf3-609b3aae12b3 on_hand: 5 allocated: 0 available: 5 total_value: '43.75' avg_unit_value: '8.7500' transaction: id: f7d36a63-008b-4973-9025-e22328786e40 type: receiving quantity: 5 unit_price: '8.7500' total_price: '43.75' transaction_id: IVT-0000154 summary: total_items: 2 total_quantity: 15 '400': $ref: '#/components/responses/Error' '401': $ref: '#/components/responses/Error' '403': $ref: '#/components/responses/Error' security: - ApiKeyAuth: [] components: parameters: IdempotencyKey: name: Idempotency-Key in: header required: false description: | Client-generated unique key for idempotent POST/PATCH/DELETE operations. Alias for the Idempotency parameter. Max 255 chars. On retry with the same key, the original response is returned without re-executing the operation. Keys expire after 24 hours. schema: type: string maxLength: 255 responses: Error: description: Error response (400/401/403/404/409/422/429/500) content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' schemas: 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 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. ````