All workInvoice extractor
Invoices and purchase orders, as PDF or photo, become checked data. The AI reads the document; the code redoes quantity times price, the sum of items and the total, validates the CNPJ (the Brazilian company ID), including the new alphanumeric format, and checks the digit of the access key. It is a demo with fictional documents and companies.
Server, validation and exports in Python, and the review screen.
Fictional documents and companies, no real client.
The model is told to copy what is printed, even when it is wrong. If it corrected things, validation would never see the error in the document. The sample has an error on purpose: 25 x 18.90 printed as 427.50, and the system points it out on the line and on the subtotal.
Giving the model 28 optional fields returned "400 Schema is too complex". The way out was a transport schema with every field required and a domain schema, with a round-trip test that proves nothing is lost.
The alphanumeric CNPJ has been valid since July 2026: each character counts as its code minus 48, and the last two digits stay numeric. The same care goes to the access key. In the calculations, money becomes Decimal, never float, with a tolerance based on the smallest unit of the currency.
def is_valid_cnpj(raw: str) -> bool:
s = re.sub(r"[.\-/\s]", "", raw or "").upper()
if not re.fullmatch(r"[0-9A-Z]{12}[0-9]{2}", s) or len(set(s)) == 1:
return False
vals = [ord(c) - 48 for c in s[:12]]
w1 = [5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2]
d1 = _cnpj_digit(vals, w1)
d2 = _cnpj_digit(vals + [d1], [6] + w1)
return s[12:] == f"{d1}{d2}"In a real run on September 25, 2026, with 3 fictional documents: 53 of 53, 47 of 47 and 53 of 53 fields correct, between 9.9 and 11.4 seconds each. Three documents and one run: it is not a benchmark.
The key validation caught it. The report from that run is kept with the code.
Credits: Demo with fictional documents, no real client.
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