Process Incoming Product and Invoices: Document Extraction & Manifests

# Overview

This skill guides the automated and interactive processing of inbound supplier documents (invoices / *Rechnungen* and delivery notes / *Lieferscheine*).
It covers:
- **Document Data Extraction**: Extracting structured metadata, packaging units (VPE), units of measurement, line items, and notes from document text or images.
- **Delta & Batching Updates**: Formatting and returning extracted product and document metadata via the `output_manifest` tool.

---

# 2. Extraction Tool Specification (`output_manifest`)

The extraction engine outputs structured findings via the `output_manifest` tool call.

```json
{
  "name": "output_manifest",
  "description": "Stores extracted invoice/delivery-note data: header metadata (basedata), notes, and product line items. Each component is strictly optional — only include the ones that carry new data.",
  "strict": false,
  "parameters": {
    "type": "object",
    "additionalProperties": false,
    "required": [],
    "properties": {
      "basedata": {
        "anyOf": [
          {
            "type": "object",
            "additionalProperties": false,
            "properties": {
              "date": { "type": ["string", "null"], "description": "Document date (ISO 8601, YYYY-MM-DD)" },
              "lieferant_id": { "type": ["number", "null"], "description": "Lieferant ID if matched, else null" },
              "lieferantName": { "type": "string", "description": "Supplier name" },
              "manifestNr": { "type": ["string", "null"], "description": "Lieferscheinnummer or Rechnungsnummer" },
              "manifestType": {
                "anyOf": [
                  { "type": "string", "enum": ["rechnung", "lieferschein"] },
                  { "type": "null" }
                ],
                "description": "Document type"
              }
            }
          },
          { "type": "null" }
        ],
        "description": "Header/metadata. Only include fields that are currently missing or changed."
      },
      "notes": {
        "anyOf": [
          { "type": "array", "items": { "type": "string" } },
          { "type": "null" }
        ],
        "description": "New noteworthy details (in German), for a human to double-check the result."
      },
      "items": {
        "anyOf": [
          {
            "type": "object",
            "additionalProperties": false,
            "properties": {
              "numberOfItemsToAdd": { "type": "number", "description": "Number of NEW line items being added in this call." },
              "items": {
                "type": "array",
                "description": "Invoice/delivery product line items",
                "items": {
                  "type": "object",
                  "additionalProperties": false,
                  "required": ["position", "count", "vpe", "unit", "articleName", "liefArtNr", "mwst", "eknetto"],
                  "properties": {
                    "position": { "type": "number", "description": "Position number" },
                    "count": { "type": "number", "description": "Quantity (Menge)" },
                    "vpe": { "type": "number", "description": "Packaging unit size (VPE). Default: 1." },
                    "unit": { "type": "string", "description": "Unit of the individual sellable item. NEVER 'VE' or 'VPE'." },
                    "articleName": { "type": "string", "description": "Article name" },
                    "liefArtNr": { "type": "string", "description": "Supplier article number" },
                    "mwst": {
                      "anyOf": [{ "type": "string", "enum": ["7", "19"] }, { "type": "null" }],
                      "description": "VAT rate percentage; null if delivery note or missing"
                    },
                    "eknetto": { "type": ["number", "null"], "description": "Net purchase price per VPE in euro cents; null if missing" }
                  }
                }
              }
            }
          },
          { "type": "null" }
        ],
        "description": "New product line items."
      }
    }
  }
}
```