Crate invoic_checker 

Automated INVOIC plausibility and tariff validation, over BO4E.

An invoice recipient — an LF, an NB or an ESA — receives INVOIC messages (PIDs 31001–31011) from NB/GNB/MSB/BIKO counterparties for grid fees (NNE), meter charges, Leistungen des Preisblatts B and Mehr-/Mindermengen (MMM) settlement. This library runs automated business-rule checks over BO4E Rechnung objects — the industry-standard German energy domain model — and produces a CheckReport that drives the REMADV / dispute workflow in invoicd.

Boundary with mako-pruefung

mako-pruefung decides published BDEW Antwortcodes for the wire and knows nothing but Prüfschritte. This crate decides mako’s own Findings for the operator queue and the § 147 AO receipt, over BO4E, for every INVOIC PID — including those with no Entscheidungsbaum. The dependency runs one way: this crate maps BO4E onto mako_pruefung::rechnung’s Prüfschritte and calls the walk, which holds no BO4E or money type. See the README for why they are not one crate.

Where a plausibility check asks the same question as a Prüfschritt — position arithmetic against A20, the document total against A24, the tax breakdown against A22/A23 — both paths read the same tolerance: Summen-level total_tolerance_ppm, position-level arithmetic_tolerance_ppm. Two knobs for one question would let the engine record a TotalMismatch Dispute while the walk dispatched a Zahlungsavis.

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::current::{PreisblattNetznutzung, Rechnung};

let preisblatt_store = InMemoryPreisblattStore::default();

// A `Rechnung` that states no Umsatzsteuer is disputed: §14 Abs. 4 Nr. 8
// UStG makes the rate and the amount mandatory, and without them the
// recipient has no Vorsteuerabzug.
let rechnung = Rechnung::default();
let report = InvoicCheckEngine::check(
    31001,
    "9900357000004",
    &rechnung,
    &preisblatt_store,
    &CheckConfig::default(),
);
assert_eq!(report.outcome, CheckOutcome::Dispute);

Re-exports

pub use amount::EuroAmount;

pub use check::CheckConfig;

pub use check::CheckOutcome;

pub use check::CheckReport;

pub use check::Finding;

pub use check::FindingKind;

pub use check::InvoicCheckEngine;

pub use check::is_stornierung;

pub use error::CheckError;

pub use rechnung::EmpfaengerFakten;

pub use rechnung::StornoEmpfaengerFakten;

pub use rechnung::antwort_auf_erneute_rechnung;

pub use rechnung::antwort_auf_rechnung;

pub use rechnung::antwort_auf_stornorechnung;

pub use tariff::InMemoryPreisblattStore;

pub use tariff::PreisblattStore;

Modules

amount

Monetary amount type for INVOIC plausibility checks.

check

INVOIC plausibility check engine — operates on BO4E Rechnung.

error

Errors from the invoic-checker pipeline.

rechnung

The ESA’s own invoice check — E_0264 / E_0266, driven off a BO4E Rechnung.

tariff

Price-sheet store — seeded from PRICAT 27003 EDIFACT messages.