"""DOC-004: Original-vs-Kopie-Kennzeichnung bei Dokumenten.

Revision ID: 0029_dokument_original
Revises: 0028_fk_indizes
Create Date: 2026-09-08
"""
from typing import Sequence, Union

from alembic import op

revision: str = "0029_dokument_original"
down_revision: Union[str, None] = "0028_fk_indizes"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.execute(
        "ALTER TABLE dokument ADD COLUMN ist_original BOOLEAN NOT NULL DEFAULT false"
    )
    # Default nur für den Backfill nötig - künftige Inserts geben es immer
    # explizit an (Anwendungsebene).
    op.execute("ALTER TABLE dokument ALTER COLUMN ist_original DROP DEFAULT")


def downgrade() -> None:
    op.execute("ALTER TABLE dokument DROP COLUMN ist_original")