Transition the purchase order state
Procurement module
POST/purchase-orders/{id}/transitionspurchaseOrders.transition
Moves the purchase order lifecycle to another state through its transition RPC, which writes the transition ledger. Uses compare-and-set on `expected_state`; a disallowed transition returns a 422 refusal. Requires `Idempotency-Key`; a replay returns the original response. A rule that refuses the request returns 422 with `refusal` and `reason`.
- Requires the capability procurement.po.write.
- OAuth scopes: procurement.
- Send an Idempotency-Key header. A replay with the same key returns the original response.
- Error statuses: 400, 401, 404, 409, 422, 429. Errors are RFC 9457 problem details.
Path and query parameters
| Field | Type | Required | Description |
|---|---|---|---|
| id | string (uuid) | Yes | Identifier of the purchase order. |
Request body: PurchaseOrderTransitionRequest
| Field | Type | Required | Description |
|---|---|---|---|
| expected_state | string | Yes | The state the caller believes the row is in (compare-and-set).Constraints: pattern ^[A-Z][A-Za-z]*( [A-Z][A-Za-z]*)*$ |
| to_state | string | Yes | Target state.Constraints: pattern ^[A-Z][A-Za-z]*( [A-Z][A-Za-z]*)*$ |
| reason | string | No | Reason, required by some transitions.Constraints: length 1 to any |
{
"expected_state": "Approved",
"to_state": "Sent",
"reason": "Client approved the revised scope."
}Response 200: PurchaseOrder
| Field | Type | Required | Description |
|---|---|---|---|
| id | string (uuid) | Yes | Identifier of the purchase order. |
| org_id | string (uuid) | Yes | Identifier of the owning organization, derived from the parent row and never accepted from the caller. |
| created_at | string (date-time) | Yes | When the row was created. |
| created_by | string (uuid) | null | Yes | Identifier of the person who created the row; null when a seed, platform or system process created it. |
| updated_at | string (date-time) | Yes | When the row was last updated. |
| updated_by | string (uuid) | null | Yes | Identifier of the person who last updated the row; null when a seed, platform or system process updated it. |
| project_id | string (uuid) | Yes | Identifier of the project. |
| vendor_id | string (uuid) | Yes | Identifier of the vendor. |
| po_number | integer | Yes | Number from the project's display key sequence.Constraints: range 1 to any |
| currency_code | string | Yes | ISO 4217 currency code of every money field.Constraints: pattern ^[A-Z]{3}$ |
| po_state | "Proposed" | "Approved" | "Sent" | "Closed" | "Canceled" | Yes | Purchase order state. |
| rfq_response_id | string (uuid) | null | Yes | Identifier of the awarded RFQ response the order comes from. |
| delivery_due_on | string (date) | null | Yes | Date the order is due to be delivered. |
| payment_terms_days | integer | null | Yes | Days after invoice the order is payable (Net 30 is 30).Constraints: range 0 to any |
| tax_minor | integer (int64) | null | Yes | Tax on the order. Integer minor units of the resource currency; null means unpriced, never zero. |
| shipping_minor | integer (int64) | null | Yes | Shipping charged on the order. Integer minor units of the resource currency; null means unpriced, never zero. |
| sent_at | string (date-time) | null | Yes | When the order moved to Sent (its issue date), from its transition ledger. |
| invoiced_minor | integer (int64) | null | Yes | Subtotal of the invoices matched to the order; null when none is matched or one is unpriced. Integer minor units of the resource currency; null means unpriced, never zero. |
| paid_minor | integer (int64) | null | Yes | Payments applied to the invoices matched to the order; null when none is matched. Integer minor units of the resource currency; null means unpriced, never zero. |
{
"id": "0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f",
"org_id": "0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f",
"created_at": "2026-10-08T14:30:00Z",
"created_by": "0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f",
"updated_at": "2026-10-08T14:30:00Z",
"updated_by": "0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f",
"project_id": "0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f",
"vendor_id": "0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f",
"po_number": 7,
"currency_code": "USD",
"po_state": "Proposed",
"rfq_response_id": "0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f",
"delivery_due_on": "2026-10-08",
"payment_terms_days": 30,
"tax_minor": 4200,
"shipping_minor": 15000,
"sent_at": "2026-10-08T14:30:00Z",
"invoiced_minor": 1250000,
"paid_minor": 600000
}Code samples
curl -X POST "$XOS_BASE_URL/purchase-orders/0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f/transitions" \
-H "Authorization: Bearer $XOS_API_KEY" \
-H "Idempotency-Key: $(uuidgen)" \
-H "Content-Type: application/json" \
-d '{"expected_state":"Approved","to_state":"Sent","reason":"Client approved the revised scope."}'const { data } = await xos.purchaseOrders.transition("0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f", {
"expected_state": "Approved",
"to_state": "Sent",
"reason": "Client approved the revised scope."
});response = xos.purchase_orders.transition("0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f", {"expected_state": "Approved", "to_state": "Sent", "reason": "Client approved the revised scope."})xos purchase-orders transition 0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f --data '{"expected_state":"Approved","to_state":"Sent","reason":"Client approved the revised scope."}'