"""add thread_state for per-thread state machine

Revision ID: 3f1d9a5b7c42
Revises: cd0a88ef9080
Create Date: 2026-04-24 10:00:00.000000

Таблица состояния треда (одна строка на тред): текущая ветка, шаг внутри ветки
и собранные слоты (JSON). Нужна для state machine в Спринте 5.
"""
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa


revision: str = '3f1d9a5b7c42'
down_revision: Union[str, None] = 'cd0a88ef9080'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.create_table(
        'thread_state',
        sa.Column('thread_id', sa.Integer(), nullable=False),
        sa.Column('current_intent_code', sa.String(length=50), nullable=True),
        sa.Column('current_step', sa.Integer(), nullable=False, server_default='0'),
        sa.Column('slots_json', sa.Text(), nullable=False, server_default='{}'),
        sa.Column('updated_at', sa.DateTime(timezone=True), nullable=False),
        sa.ForeignKeyConstraint(
            ['thread_id'], ['threads.id'], name='fk_thread_state_thread_id', ondelete='CASCADE',
        ),
        sa.PrimaryKeyConstraint('thread_id'),
    )


def downgrade() -> None:
    op.drop_table('thread_state')