finic-kairos

Python client for Kairos. Track financial events, then ask for a decision at the moment of action.

• Python 3.9 or later
• No dependencies: the standard library only
• Typed (py.typed), and safe to use from several threads

This page is the short version. The full Python SDK guide covers every call, and the TypeScript guide explains actions, labels, links and how to get good decisions in depth.

Install

Install it from PyPI:

pip install finic-kairos

Use

import os
from kairos import Kairos

kairos = Kairos(os.environ["KAIROS_API_KEY"])

# Once, at startup: say what you want decided, in plain language.
kairos.define_action("bank_transfer", {
    "subject": "user",
    "hold": "Should the pending bank transfer be held because the account shows signs of fraud or account takeover?",
    "reasons": {
        "new_device": "The current session uses a device that the account did not use before",
        "new_beneficiary": "The transfer goes to a beneficiary that was added recently",
    },
})

# Anywhere: record what happens. Any event type, any properties.
# A key that ends in _id names an entity: user_id is the entity "user".
kairos.track("transaction", {
    "user_id": "user_123",
    "account_id": "account_456",
    "recipient_id": "recipient_789",
    "amount": 9500,
    "currency": "USD",
})

# At the moment of action: ask.
decision = kairos.decide(
    "bank_transfer",
    {"user_id": "user_123", "recipient_id": "recipient_789", "amount": 9500},
    fallback="review",
)

if decision.decision == "approve":
    ...  # release the transfer

track returns at once and sends in the background. decide waits for the answer, sends what is queued first, and returns the fallback when Kairos cannot answer.

In a web framework

KairosASGI takes the user and the session from the request, for FastAPI, Starlette and any other ASGI framework. It can also send an event for a route that has no track call.

from kairos.middleware import KairosASGI

app.add_middleware(
    KairosASGI,
    client=kairos,
    entities=lambda scope: {"user": scope["state"].get("user_id")},
    session=lambda scope: scope["state"].get("session_id"),
    routes={"PUT /account/password": "password_changed"},
)

kairos.track("transaction", {"amount": 900})  # the user and the session come from the request

See In a web framework.

Import history from files

python -m kairos import events transactions.csv --type transaction --ts created_at --id txn_id --dry-run

See Import your history.

Test

python3 -m unittest discover -s packages/sdk-python/tests     # no network
python3 packages/sdk-python/examples/live_check.py            # against a running server