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Execution Provenance ​

Government agencies must be able to reproduce a specific decision months or years later, with the exact same result. Dutch administrative law requires this (Awb Art. 3:46, the AERIUS rulings), and the EU AI Act makes it mandatory for high-risk systems from August 2026.

Determinism within a single execution is necessary but not sufficient. Reproducibility requires pinning three things: the regulation YAML, the schema version it conforms to, and the engine version that executed it.

The Execution Receipt ​

Every execution produces an Execution Receipt: an output envelope that contains everything needed to reproduce the result.

json
{
  "provenance": {
    "engine": "regelrecht",
    "engine_version": "0.6.0",
    "schema_version": "v0.5.1",
    "regulation_id": "wet_op_de_zorgtoeslag",
    "regulation_valid_from": "2025-01-01",
    "regulation_hash": "sha256:a1b2c3..."
  },
  "scope": {
    "loaded_regulations": [
      { "id": "wet_op_de_zorgtoeslag", "valid_from": "2025-01-01", "hash": "sha256:a1b2c3..." },
      { "id": "regeling_zorgverzekering", "valid_from": "2025-01-01", "hash": "sha256:b2c3d4..." }
    ]
  },
  "execution": {
    "calculation_date": "2025-01-01",
    "parameters": { "bsn": "999993653" }
  },
  "results": {
    "outputs": { "heeft_recht_op_zorgtoeslag": true, "hoogte_zorgtoeslag": 209692 },
    "trace": { }
  }
}

The receipt records which engine version and schema produced the result, which regulations were loaded (with content hashes), the input parameters, and the full output with trace.

Schema and engine versioning ​

The schema defines the regulation format. The engine interprets and executes regulations that conform to the schema. These are versioned independently:

  • Schema versions are immutable directories under schema/ (e.g., schema/v0.5.1/schema.json). A published version is never modified.
  • Engine versions correspond to GitHub Release tags. Each release declares which schema versions it supports.

This distinction matters because third-party organisations may build their own engine implementations. The schema is the specification; the engine is one implementation of it.

Cross-organisation reproducibility ​

When a decision depends on values from other organisations (via Multi-Org Execution), the receipt captures the provenance of each accepted value:

json
{
  "accepted_values": [
    {
      "output": "toetsingsinkomen",
      "value": 3200000,
      "authority": "inspecteur",
      "engine_version": "0.5.1",
      "regulation_hash": "sha256:d4e5f6...",
      "signed": true
    }
  ]
}

When reproducing the decision, the engine uses these sealed accepted values rather than re-calling the other organisation. The other organisation may now be running a different engine version. A beschikking stands once issued — the accepted value at the time is a legal fact.

What this enables ​

A reproducible decision with a sealed receipt is a different animal from an opaque one. A citizen requests their trace and sees which rules applied. An auditor re-runs the computation and gets the same number. A court reconstructs the reasoning step by step. And when a bug surfaces, every affected decision can be found by querying receipts for the engine version and regulation hash.

Further reading ​