core-invoice-sys

C ABI for core_invoice_validate / _ubl, convert, diff, version. Returns 0 valid, 1 invalid, 2 unreadable / bad args.

#include "core_invoice.h"
#include <stdio.h>

int main(void) {
    const char *xml = "<!-- load a Peppol UBL document -->";
    char err[512];
    int rc = core_invoice_validate_ubl(xml, "peppol", err, sizeof err);
    if (rc == 0) puts("valid");
    else fprintf(stderr, "%s\n", err);
    return rc;
}

1.0 Python surface is validate_xml only (python/core_invoice.py via ctypes, 0|1|2). convert / diff / version are C and CLI. Not a second parser. No PyPI wheel.

The semantic crate (core-invoice) is the WASM target — cargo build -p core-invoice --target wasm32-unknown-unknown — the model, not a browser AP. Formats/sys are not that job.