> ## 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. # Preview what voiding a vendor bill would move > What voiding this bill would move for its landed cost, from the same plan the void posts: per FIFO layer (the bumped layers and every layer the charge followed a transfer, a work order or a customer return into) and per GL account (inventory, cost of goods sold, landed clearing and any account units were adjusted or written off into), the share at the moment of the preview, the negative attribution the order lines will receive, and the refusal the void would answer (units in transit, sent to another company, held in quarantine, or left stock with no record of where their cost went). Reads only. 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 /vendor-bills/{id}/void-preview 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: /vendor-bills/{id}/void-preview: parameters: - name: id in: path required: true schema: type: string format: uuid get: tags: - Purchasing summary: Preview what voiding a vendor bill would move description: >- What voiding this bill would move for its landed cost, from the same plan the void posts: per FIFO layer (the bumped layers and every layer the charge followed a transfer, a work order or a customer return into) and per GL account (inventory, cost of goods sold, landed clearing and any account units were adjusted or written off into), the share at the moment of the preview, the negative attribution the order lines will receive, and the refusal the void would answer (units in transit, sent to another company, held in quarantine, or left stock with no record of where their cost went). Reads only. 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: previewVendorBillVoidV1 responses: '200': description: The void preview. content: application/json: schema: $ref: '#/components/schemas/LandedVoidPreview' '401': $ref: '#/components/responses/Error' '403': $ref: '#/components/responses/Error' '404': $ref: '#/components/responses/Error' security: - ApiKeyAuth: [] components: schemas: LandedVoidPreview: type: object properties: data: type: object properties: bill_id: type: string format: uuid bill_number: type: string status: type: string has_landed_allocation: type: boolean refusal: type: object nullable: true properties: code: type: string enum: - landed_reversal_units_in_transit - landed_reversal_units_left_the_company - landed_reversal_units_held - landed_reversal_units_untraceable hint: type: string meta: type: object landed_reversal: type: object nullable: true properties: split: type: object properties: landed_total_cents: type: integer inventory_cents: type: integer cogs_cents: type: integer nullable: true other_accounts: type: array items: type: object properties: account_id: type: string format: uuid cents: type: integer at_allocation: type: object properties: inventory_cents: type: integer cogs_cents: type: integer negative_attribution_cents: type: integer accounts: type: array items: type: object properties: account_id: type: string format: uuid account_number: type: string nullable: true account_name: type: string nullable: true role: type: string enum: - inventory - cogs - landed_cost_clearing - other at_allocation_cents: type: integer reversal_cents: type: integer description: >- What the void moves on this account (contra plus carry) in cents; the rows sum to zero.: null layers: type: array items: type: object properties: kind: type: string enum: - bumped - followed layer_id: type: string format: uuid product_id: type: string format: uuid location_id: type: string format: uuid variant_id: type: string format: uuid nullable: true remaining_qty: type: number unit_cost_delta: type: number inventory_cents: type: integer product_title: type: string nullable: true sku: type: string nullable: true location_name: type: string nullable: true receipt_reference: type: string nullable: true receipt_kind: type: string nullable: true po_number: type: string nullable: true negative_attribution: type: array items: type: object properties: order_item_id: type: string format: uuid cents: type: integer compensations_followed: type: array items: type: object 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.