File size: 3,920 Bytes
7ff7119 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 | """Invoice math validation — Python deterministic, NOT LLM-dependent.
Mirrors prototype-agentic-langgraph's validate_invoice_math:
* line items' net total ≈ total_net (±1 tolerance)
* total_net + total_vat ≈ total_gross (±1 tolerance)
* per-line: net × VAT% ≈ vat amount (max(1, net × 1%))
* per-line: net + vat ≈ gross
Every math error is severity "high" (below ±1 is considered fine; above is suspicious).
"""
from __future__ import annotations
from utils.numbers import coerce_number
def validate_invoice_math(extracted: dict) -> list[dict]:
"""Invoice arithmetic validation. Returns a list of risk dicts."""
errors: list[dict] = []
items = extracted.get("line_items") or []
net_total = coerce_number(extracted.get("total_net"))
vat_total = coerce_number(extracted.get("total_vat"))
gross_total = coerce_number(extracted.get("total_gross"))
# Line items' net total ≈ total_net
if items and net_total is not None:
calc = 0.0
for item in items:
if not isinstance(item, dict):
continue
n = coerce_number(item.get("total_net"))
if n is not None:
calc += n
if calc > 0 and abs(calc - net_total) > 1:
errors.append({
"type": "math_error",
"severity": "high",
"message": (
f"Line items' net total ({calc:.0f}) does not match "
f"the document total ({net_total:.0f})"
),
})
# net_total + vat_total ≈ gross_total
if net_total is not None and vat_total is not None and gross_total is not None:
expected = net_total + vat_total
if abs(expected - gross_total) > 1:
errors.append({
"type": "math_error",
"severity": "high",
"message": (
f"Net ({net_total:.0f}) + VAT ({vat_total:.0f}) = "
f"{expected:.0f}, but gross = {gross_total:.0f}"
),
})
# Per-line item math
for idx, item in enumerate(items):
if not isinstance(item, dict):
continue
item_net = coerce_number(item.get("total_net"))
item_vat = coerce_number(item.get("total_vat"))
item_gross = coerce_number(item.get("total_gross"))
item_vat_rate = coerce_number(item.get("vat_rate"))
name = item.get("description", f"item #{idx + 1}")
# VAT calc: net × rate/100 ≈ vat amount
if (
item_net is not None
and item_vat_rate is not None
and item_vat is not None
and item_vat_rate > 0
):
expected_vat = item_net * item_vat_rate / 100
tol = max(1.0, item_net * 0.01)
if abs(expected_vat - item_vat) > tol:
errors.append({
"type": "math_error",
"severity": "high",
"message": (
f"Line '{name}': net ({item_net:.0f}) × "
f"{item_vat_rate:.0f}% = {expected_vat:.0f}, "
f"but VAT = {item_vat:.0f}"
),
})
# Gross: net + vat ≈ gross
if (
item_net is not None
and item_vat is not None
and item_gross is not None
):
expected_gross = item_net + item_vat
if abs(expected_gross - item_gross) > 1:
errors.append({
"type": "math_error",
"severity": "high",
"message": (
f"Line '{name}': net ({item_net:.0f}) + "
f"VAT ({item_vat:.0f}) = {expected_gross:.0f}, "
f"but gross = {item_gross:.0f}"
),
})
return errors
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