"""add current_step_code to thread_state (Спринт 6a)

Revision ID: b5e91c2d07f1
Revises: a4c82f1b9e33
Create Date: 2026-04-24 18:45:00.000000

В state machine v2 шаги идентифицируются строковыми кодами (intro/qualify/...).
Старая колонка `current_step` (int) осталась для обратной совместимости отображения,
но не используется логикой state machine.
"""
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa


revision: str = 'b5e91c2d07f1'
down_revision: Union[str, None] = 'a4c82f1b9e33'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    with op.batch_alter_table('thread_state', recreate='always') as batch:
        batch.add_column(sa.Column('current_step_code', sa.String(length=50), nullable=True))


def downgrade() -> None:
    with op.batch_alter_table('thread_state', recreate='always') as batch:
        batch.drop_column('current_step_code')