User with LDAP uid john.doe and email john.doe@example.com logs in for the first time
Taiga creates user with username johndoe (dot stripped)
User logs in again via LDAP
Plugin searches for username john.doe - not found
Plugin tries to create new user - fails with duplicate email error

Error Log:

taiga.users.models.User.DoesNotExist: User matching query does not exist.
During handling of the above exception, another exception occurred:
django.db.utils.IntegrityError: duplicate key value violates unique constraint "users_user_email_243f6e77_uniq"
Proposed Fix
Option A: Normalize username before lookup (strip dots to match Taiga's behavior)
python@transaction.atomic
def ldap_register(username: str, email: str, full_name: str):
    user_model = get_user_model()
    normalized_username = username.replace('.', '')
    try:
        user = user_model.objects.get(username=normalized_username)
    except user_model.DoesNotExist:
        user = user_model.objects.create(
            email=email,
            username=normalized_username,
            full_name=full_name
        )
    return user
Option B: Lookup by email as fallback
python@transaction.atomic
def ldap_register(username: str, email: str, full_name: str):
    user_model = get_user_model()
    try:
        user = user_model.objects.get(username=username)
    except user_model.DoesNotExist:
        if email:
            try:
                user = user_model.objects.get(email=email)
                return user
            except user_model.DoesNotExist:
                pass
        user = user_model.objects.create(
            email=email,
            username=username,
            full_name=full_name
        )
    return user