Metamorph/backend/app/api/_validation.py

"""Lightweight email validator that tolerates internal/lab TLDs (.local, .corp, …).

`pydantic.EmailStr` relies on `email-validator` with `globally_deliverable=True`,
which rejects RFC 6761 special-use domains. Red-team and corporate intranet
deployments routinely use such suffixes — we accept any RFC-shape email and
defer deliverability checks to the operator.
"""

from __future__ import annotations

import re
from typing import Annotated

from pydantic import AfterValidator

# Permissive RFC-shape pattern: local-part 1..64 chars, domain has at least one
# dot, each label is 1..63 chars of letters/digits/hyphens, total ≤ 254.
_EMAIL_RE = re.compile(
    r"^(?=.{1,254}$)[A-Za-z0-9._%+\-]{1,64}@[A-Za-z0-9](?:[A-Za-z0-9\-]{0,61}[A-Za-z0-9])?(?:\.[A-Za-z0-9](?:[A-Za-z0-9\-]{0,61}[A-Za-z0-9])?)+$"
)


def _validate_email(value: str) -> str:
    v = value.strip()
    if not _EMAIL_RE.match(v):
        raise ValueError("not a valid email address")
    return v.lower()


Email = Annotated[str, AfterValidator(_validate_email)]