Automated INVOIC plausibility and tariff validation for the LF (Lieferant) role.

A German LF receives INVOIC messages (PIDs 31001–31011) from NB/GNB/MSB/BIKO counterparties for grid fees (NNE), meter charges, and Mehr-/Mindermengen (MMM) settlement. This library runs automated business-rule checks over BO4E [Rechnung][rubo4e::v202501::Rechnung] objects — the industry-standard German energy domain model — and produces a [CheckReport] that drives the REMADV / dispute workflow in invoicd.

EDIFACT INVOIC segments
  → [makod adapter: anti-corruption layer]
  → BO4E Rechnung            — industry-standard domain model, stored in events
  → InvoicCheckEngine::check — pure business rules, no EDIFACT dependency
  → CheckReport { Ok | Warn | Dispute }
      → REMADV auto-dispatch or dispute workflow

Design principles

• Format-agnostic: zero dependency on edifact-rs. Operates solely on the BO4E domain model. EDIFACT → BO4E translation belongs in the makod transport adapter (anti-corruption layer).
• Pure library — no I/O, no async, no Tokio dependency.
• Trait-injected stores — [PreisblattStore] is injected by the caller (e.g. invoicd injects an in-memory store seeded from marktd's price-sheet API).
• No floating-point money — all amounts are [EuroAmount] (i64 ×10⁻⁵ EUR).

Monetary precision

[EuroAmount] stores values as i64 in units of 10⁻⁵ EUR (1/100 000 EUR):

• EuroAmount(100_000) = 1.00000 EUR
• EuroAmount(3_456) = 0.03456 EUR (typical NNE unit price per kWh)

This gives five decimal places — sufficient for all BDEW INVOIC precision requirements (NNE unit prices: typically 4 decimal places).

Example

use invoic_checker::{
    check::{CheckConfig, CheckOutcome, InvoicCheckEngine},
    tariff::InMemoryPreisblattStore,
    amount::EuroAmount,
};
use rubo4e::v202501::{PreisblattNetznutzung, Rechnung};

let preisblatt_store = InMemoryPreisblattStore::default();

let rechnung = Rechnung::default();
let report = InvoicCheckEngine::check(
    31001,
    "9900357000004",
    &rechnung,
    &preisblatt_store,
    &CheckConfig::default(),
);
assert_eq!(report.outcome, CheckOutcome::Ok);