The invoice counter (seq)

Invoices, receipts (payments) and credit notes (returns) are also numbered by a gap-free counter per company and per stream, seq. It is given once, when the document is issued, and never changes. If all you need is “what has been issued since I last looked”, keep that one integer per stream instead of a version.

GET /invoices/cursor
→ {"data": {"last_seq": 41, "high_water": 9140}}          start from "now"

GET /invoices?filter[seq_after]=41
→ {"data": [ …invoices 42, 43 in issue order… ],
   "meta": {"last_seq": 43, "has_more": false}}

Store meta.last_seq and ask with it next time. Because the counter has no gaps, you can also check what you hold: if you have 41 and the next answer starts at 43, something is wrong on your side — ask for filter[id] or re-read from 41.

Stream	Cursor	seq is given when
Invoices	GET /invoices/cursor	the invoice is issued
Payments	GET /payments/cursor	the receipt is issued (a payment’s seq is its receipt’s)
Returns	GET /returns/cursor	the return is credited (credit_note_number is set)

Caution

filter[seq_after] sees each document once, at issue. Later changes — a payment reversed, a cheque bounced, a return approved after it was recorded — are only seen by version or through filter[ack]=pending. Use seq to find new documents, and acks to learn what changed. filter[seq_after] can’t be combined with a version cursor.

Try it

curl -s "$SLFLO_BASE/invoices/cursor" -H "Authorization: Bearer $SLFLO_TOKEN"
curl -sg "$SLFLO_BASE/invoices?filter[seq_after]=0" -H "Authorization: Bearer $SLFLO_TOKEN" \
  | jq '{seqs: [.data[].seq], meta}'
# on the sandbox: {"seqs": [1, 2], "meta": {"has_more": false, "last_seq": 2, "per_page": 100}}

The whole flow, with gap checks and acks, is Read invoices by seq.