"""Persist the documented knowledge-space data policy."""

from __future__ import annotations

import sqlalchemy as sa
from alembic import op

revision = "0004_space_data_policy"
down_revision = "0003_identity_credentials"
branch_labels = None
depends_on = None


def upgrade() -> None:
    """Add an explicit policy column with the contract's local-only default."""

    op.add_column(
        "spaces",
        sa.Column("data_policy", sa.String(32), nullable=False, server_default="local_only"),
        schema="control",
    )
    op.alter_column("spaces", "data_policy", server_default=None, schema="control")


def downgrade() -> None:
    """Remove only the policy column introduced by this migration."""

    op.drop_column("spaces", "data_policy", schema="control")