decision-verifier

A minimal reference implementation for deterministic decision equivalence verification.

⚠️ Important

This verifier does NOT define equivalence as structural or hash equality. This repository is a minimal reference scaffold, not a complete implementation of Guardian v0.2.

Decision equivalence is determined by invariant boundary equality, as defined in Guardian v0.2.

Canonicalization is used only as a deterministic encoding step, not as a semantic equivalence criterion.

Scope

• Exposes POST /verify
• Accepts decision_a and decision_b
• Performs deterministic canonicalization:
  • Sorts dictionary keys
  • Removes unnecessary whitespace
• Performs deterministic normalization (current implementation)
• Uses canonical hashing as a temporary comparison mechanism
• NOTE: This is NOT the final equivalence model (see Guardian v0.2)
  • equivalent
  • canonical_hash_a
  • canonical_hash_b ⚠️ Current implementation uses structural comparison as a placeholder. Semantic invariant-based equivalence is defined in Guardian v0.2 and will replace this.

Non-goals

• No policy engine
• No DID / signature / receipt / attestation
• No runtime integration
• No database

This project is intentionally minimal and intended as a reference implementation.

Quick Start

python -m venv .venv
. .venv/Scripts/activate
pip install -r requirements.txt
uvicorn app.main:app --reload

API

POST /verify

Request body:

{
  "decision_a": {"id": "D-001", "result": "allow"},
  "decision_b": {"result": "allow", "id": "D-001"}
}

Response body:

{
  "equivalent": true,
  "canonical_hash_a": "<sha256-hex>",
  "canonical_hash_b": "<sha256-hex>"
}

Run Tests

pytest

Example Files

• examples/equal_a.json
• examples/equal_b.json
• examples/different.json