"""customers 003 - add birth_date column

Adds an optional birth_date column to the customers table so that
self-enrollment flows (e.g. loyalty) can persist the customer's birthday
collected on the enrollment form. Previously the field was collected by
the UI and accepted by the loyalty service signature, but never written
anywhere — see Phase 1.4 of the loyalty production launch plan.

Revision ID: customers_003
Revises: customers_002
Create Date: 2026-04-09
"""
import sqlalchemy as sa

from alembic import op

revision = "customers_003"
down_revision = "customers_002"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.add_column(
        "customers",
        sa.Column("birth_date", sa.Date(), nullable=True),
    )


def downgrade() -> None:
    op.drop_column("customers", "birth_date")
