> ## 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 product > Updates mutable top-level fields on a product such as its name, SKU, price, weight, dimensions, category, tax settings, and reorder points; child collections such as variants, pricing tiers, and components are managed through their own sub-resource endpoints. Returns a 404 if the product does not belong to the entity, and requires the `products:write` scope. ## OpenAPI ````yaml /openapi.yaml patch /products/{id} 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: /products/{id}: patch: tags: - Products summary: Update a product description: >- Updates mutable top-level fields on a product such as its name, SKU, price, weight, dimensions, category, tax settings, and reorder points; child collections such as variants, pricing tiers, and components are managed through their own sub-resource endpoints. Returns a 404 if the product does not belong to the entity, and requires the `products:write` scope. operationId: updateProduct parameters: - name: id in: path required: true schema: type: string format: uuid - $ref: '#/components/parameters/IdempotencyKey' requestBody: required: true content: application/json: schema: type: object description: > Only allowlisted top-level fields are accepted. Sending `id`, `entity_id`, `cost`, `searchable_text`, `has_variants`, or any marketplace ID (`shopify_product_id`, `amazon_asin`, etc.) returns 400 `field_not_writable`. Cost is not writable over the API (there is no revalue route on the public API): a person sets a product's cost in Arcus with Set cost on the product page, which re-values the stock on hand with a journal entry and pins the cost. `kit_cost_override` (the cost pin) is not writable either. properties: title: type: string description: type: string nullable: true sku: type: string nullable: true part_number: type: string nullable: true barcode: type: string nullable: true list_price: type: number category_id: type: string format: uuid nullable: true vendor_id: type: string format: uuid nullable: true is_active: type: boolean is_serialized: type: boolean charge_tax: type: boolean track_inventory: type: boolean weight: type: number nullable: true weight_uom: type: string length: type: number nullable: true width: type: number nullable: true height: type: number nullable: true length_uom: type: string quantity_uom: type: string product_tax_code: type: string nullable: true packaging_classification: type: string enum: - over_box - sioc - sipp - prep_free description: > Amazon-FBA packaging classification. See `Product` schema for full enum semantics. Invalid values return 400 `invalid_packaging_classification` from the canonical validator with hint listing the four legal values. example: sioc reorder_point: type: integer nullable: true reorder_qty: type: integer nullable: true safety_stock: type: integer metadata: type: object example: title: Widget Pro XL (updated) list_price: 54.99 packaging_classification: sioc is_active: true responses: '200': description: Updated product content: application/json: schema: type: object properties: data: $ref: '#/components/schemas/Product' '400': $ref: '#/components/responses/Error' '401': $ref: '#/components/responses/Error' '403': $ref: '#/components/responses/Error' '404': $ref: '#/components/responses/Error' security: - ApiKeyAuth: - products:write 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: Product: type: object description: Arcus ERP product (physical/kit/box/service/variant_parent). properties: id: type: string format: uuid object: type: string enum: - product entity_id: type: string format: uuid readOnly: true title: type: string description: type: string nullable: true sku: type: string nullable: true part_number: type: string nullable: true barcode: type: string nullable: true product_type: type: string enum: - physical - kit - box - service - variant_parent category_id: type: string format: uuid nullable: true vendor_id: type: string format: uuid nullable: true list_price: type: number cost: type: number readOnly: true description: >- WAC (Weighted Average Cost). ReadOnly. Writers: updateProductCostFromReceipt + recomputeKitCostForKit. is_active: type: boolean is_sellable: type: boolean default: true description: >- True (default) = appears in the sales-order/quote/invoice product picker and can be added as a sales line. False = component-only: still purchasable (POs), BOM-usable, and inventoried, but blocked from sales documents. is_serialized: type: boolean charge_tax: type: boolean track_inventory: type: boolean weight: type: number nullable: true weight_uom: type: string length: type: number nullable: true width: type: number nullable: true height: type: number nullable: true length_uom: type: string quantity_uom: type: string product_tax_code: type: string nullable: true reorder_point: type: integer nullable: true reorder_qty: type: integer nullable: true safety_stock: type: integer packaging_classification: type: string enum: - over_box - sioc - sipp - prep_free default: over_box description: > Amazon-FBA packaging classification driving Mighty's pack-order decisions. `over_box` (default): standard path, Mighty picks an over-box from the catalog and the warehouse runs the full prep step. `sioc` (Ships In Own Container): item ships in its original manufacturer container; the shipping label tapes directly onto the product packaging; no over-box and no prep. Single-item package only (cannot co-pack). `sipp` (Ships In Product Packaging): Amazon's rebrand of SIOC with identical rules: retail packaging IS ship-ready and the label goes onto it. Single-item package only. `prep_free` (Prep-Free Packaging): item still requires an over-box (Mighty picks one) but the warehouse skips the prep step (no bubble wrap, no bagging, no labels-on-product). Can co-pack with other prep-free or over_box items. Added 2026-05-18 in Phase 3 of FULFILLMENT-PRODUCTION-READINESS-CAMPAIGN; backed by the `packaging_classification` Postgres ENUM. has_variants: type: boolean readOnly: true metadata: type: object description: >- Operator-extensible JSONB. Reserved: _deleted (set by softDeleteProduct), _actor, _api. 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.