> ## 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. # Update a package's carrier > Changes the carrier and service level for a package. If a label was already purchased it is voided first, and a new label must be purchased afterward; requires `fulfillment:write` scope. ## OpenAPI ````yaml /openapi.yaml post /packages/{id}/change-carrier 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: /packages/{id}/change-carrier: parameters: - name: id in: path required: true schema: type: string format: uuid post: tags: - Fulfillment summary: Update a package's carrier description: >- Changes the carrier and service level for a package. If a label was already purchased it is voided first, and a new label must be purchased afterward; requires `fulfillment:write` scope. operationId: changePackageCarrier parameters: - $ref: '#/components/parameters/IdempotencyKey' requestBody: required: true content: application/json: schema: type: object properties: carrier: type: string service_token: type: string service_name: type: string rate_object_id: type: string responses: '200': description: Package with updated carrier and service content: application/json: schema: $ref: '#/components/schemas/Package' '400': $ref: '#/components/responses/Error' '401': $ref: '#/components/responses/Error' '403': $ref: '#/components/responses/Error' '404': $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 schemas: Package: type: object description: | A shipment / box created during fulfillment. One package contains many package items (line item splits) and at most one shipment label. properties: id: type: string format: uuid object: type: string enum: - package entity_id: type: string format: uuid readOnly: true order_id: type: string format: uuid package_number: type: string readOnly: true description: Sequential per entity. status: type: string enum: - packing - packed - labeled - shipped - delivered - returned - void readOnly: true weight_lb: type: number nullable: true length_in: type: number nullable: true width_in: type: number nullable: true height_in: type: number nullable: true carrier: type: string nullable: true description: e.g. ups, usps, fedex, dhl. service_level: type: string nullable: true description: e.g. ground, priority, 2day. tracking_number: type: string nullable: true tracking_url: type: string nullable: true ship_cost: type: number nullable: true billed_ship_cost: type: number nullable: true description: Cost billed to customer (vs purchased cost). location_id: type: string format: uuid nullable: true insurance_amount_override: type: number nullable: true description: > Manual override of the auto-computed Shippo-insurance declared value. When set, overrides the value derived from products flagged apply_freight_insurance. insurance: type: object nullable: true readOnly: true description: > Auto-insurance summary. `null` when no package item opts in and there is no override / entity threshold. `bought: true` after a label has been purchased (amount = the value actually insured at Shippo); `bought: false` projects what the next label purchase will insure. properties: active: type: boolean bought: type: boolean amount: type: number description: Insured declared value (USD). currency: type: string fee_estimate: type: number description: ~1.5% of declared value; the exact fee is in the rate. provider: type: string nullable: true description: UPS | USPS | FEDEX | DHL once the carrier is chosen. covered_items: type: array items: type: string covered_item_count: type: integer source: type: string enum: - product_toggle - entity_threshold - manual_override shipped_at: type: string format: date-time nullable: true readOnly: true delivered_at: type: string format: date-time nullable: true readOnly: true metadata: type: object nullable: true created_at: type: string format: date-time readOnly: true updated_at: type: string format: date-time readOnly: true 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.