> ## 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.

# Issue a vendor credit

> <Note>Required API key scope: `purchasing:write`</Note>

Inserts a row in the canonical `vendor_credits` ledger and posts a balanced
GL journal entry (DR vendor_returns_receivable / CR vendor_credits) under
`source_type='VENDOR_CREDIT'`. Apply the credit to an open vendor bill by
passing the credit id in `vendor_credit_ids[]` on POST /v1/ap-payments.

Idempotency: if `source_id` is supplied, the canonical helper short-circuits
on `(entity_id, source_type, source_id)` and returns the existing row with
`idempotent: true`. The `Idempotency-Key` header (standard public-API
replay guard) is also honored.




## OpenAPI

````yaml /openapi.yaml post /vendor-credits
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_<code>_<random>` (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:
  /vendor-credits:
    post:
      tags:
        - Purchasing
      summary: Issue a vendor credit
      description: >
        <Note>Required API key scope: `purchasing:write`</Note>


        Inserts a row in the canonical `vendor_credits` ledger and posts a
        balanced

        GL journal entry (DR vendor_returns_receivable / CR vendor_credits)
        under

        `source_type='VENDOR_CREDIT'`. Apply the credit to an open vendor bill
        by

        passing the credit id in `vendor_credit_ids[]` on POST /v1/ap-payments.


        Idempotency: if `source_id` is supplied, the canonical helper
        short-circuits

        on `(entity_id, source_type, source_id)` and returns the existing row
        with

        `idempotent: true`. The `Idempotency-Key` header (standard public-API

        replay guard) is also honored.
      operationId: createVendorCreditV1
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - vendor_id
                - amount
              properties:
                vendor_id:
                  type: string
                  format: uuid
                  description: Vendor account id
                amount:
                  type: number
                  description: Positive amount being credited
                  exclusiveMinimum: 0
                reason:
                  type: string
                  description: Free-text reason recorded in activity_log
                  nullable: true
                source_type:
                  type: string
                  description: Origin of the credit; recorded on the ledger row
                  enum:
                    - manual
                    - vendor_return
                    - price_adjustment
                    - rebate
                    - duplicate_payment
                    - other
                  default: manual
                source_id:
                  type: string
                  format: uuid
                  nullable: true
                  description: >-
                    Linked vendor_return or vendor_bill id (used for
                    idempotency)
                expires_at:
                  type: string
                  format: date-time
                  nullable: true
                  description: >-
                    Future date; defaults to entity setting (NULL = never
                    expire)
                notes:
                  type: string
                  nullable: true
      responses:
        '201':
          description: Created vendor credit
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    $ref: '#/components/schemas/VendorCredit'
        '400':
          $ref: '#/components/responses/Error'
        '401':
          $ref: '#/components/responses/Error'
        '403':
          $ref: '#/components/responses/Error'
        '404':
          $ref: '#/components/responses/Error'
        '422':
          $ref: '#/components/responses/Error'
      security:
        - ApiKeyAuth: []
components:
  schemas:
    VendorCredit:
      type: object
      description: |
        A vendor credit -- a ledger entry that reduces what you owe a vendor.
        Issued from a vendor return, a negotiated discount, or a manual grant.
        Posts GL: DR vendor_returns_receivable / CR vendor_credits at issuance.
        Apply to an open vendor bill via POST /v1/ap-payments with
        `vendor_credit_ids[]`. Mirrors the canonical `public.vendor_credits`
        ledger (NOT the legacy vendor_bills negative-amount pattern).
      properties:
        id:
          type: string
          format: uuid
          readOnly: true
        entity_id:
          type: string
          format: uuid
          readOnly: true
        vendor_id:
          type: string
          format: uuid
        credit_number:
          type: string
          readOnly: true
          description: Auto-generated, e.g. VC-0000001
        amount:
          type: string
          description: Total issued amount (numeric, 4 dp)
        remaining_amount:
          type: string
          readOnly: true
          description: Unapplied balance (numeric, 4 dp)
        source_type:
          type: string
          description: Origin of the credit. Free-form text; common values listed.
          enum:
            - manual
            - vendor_return
            - price_adjustment
            - rebate
            - duplicate_payment
            - other
          default: manual
        source_id:
          type: string
          format: uuid
          nullable: true
          description: Linked vendor_return or vendor_bill id when applicable
        status:
          type: string
          readOnly: true
          enum:
            - open
            - partially_applied
            - applied
            - voided
            - expired
        expires_at:
          type: string
          format: date-time
          nullable: true
          description: Forfeits remaining balance after this date; NULL = never expire
        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_<code>_<random>
        Test keys use ark_test_ent_<code>_<random>. Both are issued per entity
        via Settings > Developers > API Keys.

````