> ## 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.

# Penny-match external records against Arcus (4 resource types)

> Accepts up to 5000 external records, compares them against Arcus data,
and returns per-row mismatch details. Requires migration:read scope.
Tolerance defaults to 1 cent.




## OpenAPI

````yaml /openapi.yaml post /entities/{entity_id}/reconciliation/compare
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:
  /entities/{entity_id}/reconciliation/compare:
    post:
      tags:
        - Reconciliation
      summary: Penny-match external records against Arcus (4 resource types)
      description: |
        Accepts up to 5000 external records, compares them against Arcus data,
        and returns per-row mismatch details. Requires migration:read scope.
        Tolerance defaults to 1 cent.
      operationId: postReconciliationCompare
      parameters:
        - name: entity_id
          in: path
          required: true
          schema:
            type: string
            format: uuid
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ReconciliationCompareRequest'
      responses:
        '200':
          description: Comparison result
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ReconciliationCompareResult'
        '400':
          $ref: '#/components/responses/Error'
        '401':
          $ref: '#/components/responses/Error'
        '403':
          $ref: '#/components/responses/Error'
      security:
        - ApiKeyAuth: []
components:
  schemas:
    ReconciliationCompareRequest:
      type: object
      required:
        - external_resource
        - external_records
      properties:
        external_resource:
          type: string
          enum:
            - ar_aging_by_customer
            - ap_aging_by_vendor
            - trial_balance_by_account
            - resource_counts
        external_records:
          type: array
          maxItems: 5000
          items:
            type: object
            required:
              - external_id
            properties:
              external_id:
                type: string
              total:
                type: number
                format: double
        external_source:
          type: string
          nullable: true
        tolerance_cents:
          type: integer
          default: 1
    ReconciliationCompareResult:
      type: object
      properties:
        object:
          type: string
          enum:
            - reconciliation_compare_result
        matched:
          type: integer
        mismatched:
          type: integer
        missing_in_arcus:
          type: integer
        extra_in_arcus:
          type: integer
        mismatches:
          type: array
          items:
            type: object
        missing_in_arcus_records:
          type: array
          items:
            type: object
        extra_in_arcus_records:
          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_<code>_<random>
        Test keys use ark_test_ent_<code>_<random>. Both are issued per entity
        via Settings > Developers > API Keys.

````