contractgate (Python SDK)

First-party Python SDK for DataContractGate — a high-performance semantic contract enforcement gateway (Patent Pending).

Install

pip install contractgate

Python 3.9+. Runtime deps: httpx, PyYAML.

Quickstart — HTTP client

from contractgate import Client

cg = Client(base_url="https://gw.example.com", api_key="cg_live_...")

result = cg.ingest(
    contract_id="11111111-1111-1111-1111-111111111111",
    events=[
        {"user_id": "alice_01", "event_type": "click", "timestamp": 1712000000},
    ],
)

print(result.passed, "/", result.total, "events passed")
for r in result.results:
    if not r.passed:
        for v in r.violations:
            print(v.field, v.kind, v.message)

Async equivalent:

import asyncio
from contractgate import AsyncClient

async def main():
    async with AsyncClient(base_url="...", api_key="...") as cg:
        result = await cg.ingest(contract_id="...", events=[...])

asyncio.run(main())

Quickstart — local validator

Pure-Python port of the Rust validator. Useful in unit tests and pre-commit hooks:

from contractgate import Contract

contract = Contract.from_yaml(open("user_events.yaml").read())
compiled = contract.compile()

vr = compiled.validate({
    "user_id": "alice_01",
    "event_type": "click",
    "timestamp": 1712000000,
})
assert vr.passed, vr.violations

GitHub Action / pre-commit

Same compile, no API key:

# GitHub Actions
- uses: nightmoose/contractgate/actions/validate@main

# .pre-commit-config.yaml
repos:
  - repo: https://github.com/nightmoose/contractgate
    rev: main   # pin to a git sha
    hooks:
      - id: contractgate-validate

The hook only looks at contracts/**/*.yaml. Override files: in your config if contracts live elsewhere.

Caveats

• Local validator does not run RFC-004 PII transforms (mask, hash, drop, redact). The per-contract salt is server-side only. The gateway is the single source of truth for the post-transform payload — read it from each per-event result's transformed_event field.
• Audit honesty: every per-event result carries the contract_version that actually matched the event (relevant under multi_stable_resolution: fallback). Surface it as-is — do not substitute the requested version.
• Retries are off by default. Layer httpx.HTTPTransport(retries=) or tenacity if you need them. Avoid client-side retry on ingest to prevent double-write; use the gateway's quarantine replay endpoint instead.
• httpx is pinned >=0.25,<1.0; we'll widen once 1.x ships.

License

MIT. See LICENSE.