validators.py

"""Cheap, deterministic output checks used by Mellea's repair loop."""

from support_copilot.facts import extract_order_ids


REFUND_PROMISES = (
    "we will refund",
    "we'll refund",
    "your refund is approved",
    "refund has been approved",
)


def under_word_limit(text: str, limit: int = 120) -> tuple[bool, str]:
    count = len(text.split())
    return count <= limit, f"Reply has {count} words; the limit is {limit}."


def mentions_ticket(text: str, ticket_id: str) -> tuple[bool, str]:
    passed = ticket_id.casefold() in text.casefold()
    return passed, f"Reply must mention ticket ID {ticket_id}."


def greets_customer(text: str, customer_name: str) -> tuple[bool, str]:
    passed = customer_name.casefold() in text.casefold()
    return passed, f"Reply must greet the customer by name ({customer_name})."


def avoids_unauthorised_refund_promise(
    text: str, *, allowed: bool
) -> tuple[bool, str]:
    if allowed:
        return True, "Refund promise is authorised."
    lower = text.casefold()
    found = next((phrase for phrase in REFUND_PROMISES if phrase in lower), None)
    return found is None, "Do not promise a refund; say a specialist will review the request."


def contains_no_invented_order_id(
    text: str, trusted_source_text: str
) -> tuple[bool, str]:
    """Ensure every ID in generated text occurs in the original, trusted ticket."""
    mentioned = extract_order_ids(text)
    allowed = extract_order_ids(trusted_source_text)
    if not mentioned:
        return True, "No order identifier was introduced."
    unexpected_keys = mentioned.keys() - allowed.keys()
    unexpected = sorted(mentioned[key] for key in unexpected_keys)
    if not unexpected:
        return (
            True,
            f"Detected order IDs {sorted(mentioned.values())} all occur in the source ticket.",
        )
    return (
        False,
        f"Unexpected order IDs {unexpected}; source ticket contains "
        f"{sorted(allowed.values())}. Remove every unexpected order ID.",
    )