> ## 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. # The bank's balance on a date, with its basis named > What the BANK said this account's balance was on a given day, which is the counterpart of `cash-balance` (what the BOOKS say for the same day). Read this one against that one to reconcile the two without computing either yourself. THE FIGURE NAMES THE ASSUMPTION IT CARRIES, and you must read that before using it. On an account with no reconciliation baseline and no completed period the balance is derived by subtracting the POSTED feed rows dated after the day from the balance the institution last reported. That is correct only if the institution's reported balance is itself posted-only. Whether a bank counts its own pending items in the balance it reports is a property of that bank, so BOTH readings are returned: `balance_if_pending_excluded` (the figure this API has always published) and `balance_if_pending_included`, with `pending_after_count` and `pending_after_amount` between them. `bases_agree` is true when no pending item is dated after the day, in which case the two figures are the same number. The institution's statement for that date settles which reading it holds to. `balance_state` is `verified` (inside a completed period that ties), `computed` (walked from an anchor), `bank_current` (no anchor, walked back from the reported balance) or `none` (no figure can be derived; `bank_stated_reason` says why, e.g. `never_synced`). A `none` state returns nulls, never zeros: "I cannot say" and "zero dollars" are different answers. READ-ONLY, and it calls no third party: `bank_stated_balance` is the persisted reading as of `bank_stated_as_of`, never a live fetch, so this endpoint answers even when the institution does not. Requires `accounting:read` or `migration:read` scope. ## OpenAPI ````yaml /openapi.yaml get /entities/{entity_id}/reconciliation/bank-balance-as-of 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: /entities/{entity_id}/reconciliation/bank-balance-as-of: get: tags: - Reconciliation summary: The bank's balance on a date, with its basis named description: > What the BANK said this account's balance was on a given day, which is the counterpart of `cash-balance` (what the BOOKS say for the same day). Read this one against that one to reconcile the two without computing either yourself. THE FIGURE NAMES THE ASSUMPTION IT CARRIES, and you must read that before using it. On an account with no reconciliation baseline and no completed period the balance is derived by subtracting the POSTED feed rows dated after the day from the balance the institution last reported. That is correct only if the institution's reported balance is itself posted-only. Whether a bank counts its own pending items in the balance it reports is a property of that bank, so BOTH readings are returned: `balance_if_pending_excluded` (the figure this API has always published) and `balance_if_pending_included`, with `pending_after_count` and `pending_after_amount` between them. `bases_agree` is true when no pending item is dated after the day, in which case the two figures are the same number. The institution's statement for that date settles which reading it holds to. `balance_state` is `verified` (inside a completed period that ties), `computed` (walked from an anchor), `bank_current` (no anchor, walked back from the reported balance) or `none` (no figure can be derived; `bank_stated_reason` says why, e.g. `never_synced`). A `none` state returns nulls, never zeros: "I cannot say" and "zero dollars" are different answers. READ-ONLY, and it calls no third party: `bank_stated_balance` is the persisted reading as of `bank_stated_as_of`, never a live fetch, so this endpoint answers even when the institution does not. Requires `accounting:read` or `migration:read` scope. operationId: getReconciliationBankBalanceAsOf parameters: - name: entity_id in: path required: true schema: type: string format: uuid - name: bank_account_id in: query required: true schema: type: string format: uuid - name: as_of in: query description: YYYY-MM-DD. Defaults to today. schema: type: string format: date responses: '200': description: The bank's balance on that date, under both readings content: application/json: schema: type: object properties: object: type: string enum: - reconciliation_bank_balance_as_of entity_id: type: string format: uuid as_of: type: string format: date basis: type: string enum: - anchored - bank_current - none balance_state: type: string enum: - verified - computed - bank_current - none anchor_date: type: string format: date nullable: true verified_through: type: string format: date nullable: true period_gap_count: type: integer account_kind: type: string enum: - asset - liability balance_label: type: string balance_if_pending_excluded: type: number format: double nullable: true balance_if_pending_included: type: number format: double nullable: true pending_after_count: type: integer pending_after_amount: type: number format: double bases_agree: type: boolean bank_stated_balance: type: number format: double nullable: true bank_stated_as_of: type: string format: date-time nullable: true bank_stated_reason: type: string nullable: true bank_stated_pending_treatment: type: string '400': $ref: '#/components/responses/Error' '401': $ref: '#/components/responses/Error' '403': $ref: '#/components/responses/Error' '404': $ref: '#/components/responses/Error' security: - ApiKeyAuth: [] components: responses: Error: description: Error response (400/401/403/404/409/422/429/500) content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' schemas: 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 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. ````