Rendering postgresql dialect DOMAIN field

Describe the bug

I have the following postgres domain in my model

# adapted from html5 standard
# https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/email#basic_validation
_POSTGRES_EMAIL_RE = (
    r"^"
    r"[a-z0-9.!#$%&''*+/=?^_`{|}~-]+"
    r"@[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?"
    r"(?:\.[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?)*"
    r"$"
)

EMAIL_DOMAIN = pg_dialect.DOMAIN(
    'email',
    pg_dialect.CITEXT(),
    check=rf"value ~ '{_POSTGRES_EMAIL_RE}'"
) 

class Base(DeclarativeBase):
    pass

class Contact(Base):
    __tablename__ = 'contacts'
    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    email: Mapped[str] = mapped_column(EMAIL_DOMAIN)

When autogenerating the field, the column corresponding to the email field is rendered as:

    sa.Column('email', postgresql.DOMAIN('email', CITEXT()), nullable=False),

The rendered output is

• missing the check constraint on the model column; and
• not importing the data_type in the generated migration.

Expected behavior
The column should be rendered as

    sa.Column('email', postgresql.DOMAIN('email', postgresql.CITEXT(), check=rf"value ~ '^my_.*$'"), nullable=False),

To Reproduce
Please try to provide a Minimal, Complete, and Verifiable example, with the migration script and/or the SQLAlchemy tables or models involved.
See also Reporting Bugs on the website.

# Insert code here

Error

# Copy error here. Please include the full stack trace.

Versions.

• OS: Ubuntu 22.04.3 LTS
• Python: 3.11.2
• Alembic: 1.12.0
• SQLAlchemy: 2.0.21
• Database: 15.4
• DBAPI: psycopg[c]==3.1.12

Additional context

Split from issue #1357

Have a nice day!

Start at Alembic's PostgreSQL autogenerate rendering path for DOMAIN types and its migration import collection, reproducing the model shown in the issue. Done means generated code preserves the DOMAIN check expression and emits the required postgresql.CITEXT import, matching the expected column.