curl --request GET \
  --url https://api.sandbox.paypathiq.com/v1/clients/{clientCode}/book-completions/{externalCompletionId} \
  --header 'Authorization: Bearer <token>'

{
  "acceptedAt": "2026-10-15T02:30:00.000Z",
  "asOf": "2026-10-15T01:00:00.000Z",
  "batches": [
    "BATCH_BOOK_1",
    "BATCH_BOOK_2"
  ],
  "coveredReceivableCount": 180,
  "externalCompletionId": "BOOK_7",
  "omissions": [
    {
      "externalReceivableId": "REC_999",
      "flaggedAt": "2026-10-15T02:30:00.000Z",
      "state": "held"
    }
  ],
  "omissionsTruncated": false,
  "omittedReceivableCount": 1,
  "scope": "all_receivables",
  "sourcePosition": 7
}

{
  "detail": "API key is invalid, inactive, revoked, or for another environment.",
  "requestId": "29400000-0000-4000-8000-000000000001",
  "status": 401,
  "title": "API key is invalid, inactive, revoked, or for another environment.",
  "type": "https://docs.paypathiq.com/problems/invalid_api_key"
}

{
  "detail": "The Client code is unknown, the grant lacks the required scope, or the calling address is outside the grant's IP allowlist.",
  "requestId": "29400000-0000-4000-8000-000000000001",
  "status": 403,
  "title": "The Client code is unknown, the grant lacks the required scope, or the calling address is outside the grant's IP allowlist.",
  "type": "https://docs.paypathiq.com/problems/client_scope_denied"
}

{
  "detail": "No evidence exists at this authorized resource URL.",
  "requestId": "29400000-0000-4000-8000-000000000001",
  "status": 404,
  "title": "No evidence exists at this authorized resource URL.",
  "type": "https://docs.paypathiq.com/problems/financial_event_not_found"
}

{
  "detail": "Route parameters or the representation are invalid. Route parameters are checked before authentication. Field errors carry a code such as invalid_format, unrecognized_keys, custom, sensitive_external_id, or sensitive_source_reference.",
  "errors": [
    {
      "code": "invalid_format",
      "detail": "Invalid ISO date",
      "pointer": "/dueDate"
    }
  ],
  "requestId": "29400000-0000-4000-8000-000000000001",
  "status": 422,
  "title": "Route parameters or the representation are invalid. Route parameters are checked before authentication. Field errors carry a code such as invalid_format, unrecognized_keys, custom, sensitive_external_id, or sensitive_source_reference.",
  "type": "https://docs.paypathiq.com/problems/validation_error"
}

{
  "detail": "Each API key may send 60 requests per minute and run 1 request at a time. In sandbox, the same limits also apply per Client across all of its keys. Every request, including GET, counts.",
  "requestId": "29400000-0000-4000-8000-000000000001",
  "status": 429,
  "title": "Each API key may send 60 requests per minute and run 1 request at a time. In sandbox, the same limits also apply per Client across all of its keys. Every request, including GET, counts.",
  "type": "https://docs.paypathiq.com/problems/rate_limit_exceeded"
}

{
  "detail": "An unexpected error prevented a safe commit, and nothing was saved. Retry with backoff.",
  "requestId": "29400000-0000-4000-8000-000000000001",
  "status": 503,
  "title": "An unexpected error prevented a safe commit, and nothing was saved. Retry with backoff.",
  "type": "https://docs.paypathiq.com/problems/projection_unavailable"
}