app/engine/explain.py

_RATIONALE: dict[str, str] = {
    "ESCALATE":     "needs a human agent immediately",
    "FOLLOW_UP":    "requires follow-up from the support team",
    "LOG_FEEDBACK": "can be logged as positive feedback",
    "AUTO_RESOLVE": "can be auto-resolved with a helpful response",
}


def explain(sentiment: dict, signals: dict, decision: dict) -> str:
    dec = decision["decision"]
    label = sentiment["label"]
    conf = sentiment["confidence"]
    urgency = signals["urgency"]
    intent = signals["intent"]
    rationale = _RATIONALE.get(dec, "requires review")

    return (
        f"Decision: {dec} — message is {label} (confidence {conf:.2f})"
        f" with {urgency} urgency and a {intent} intent,"
        f" so it {rationale}."
    )