"""Add structured_delta column to musehub_commits.

structured_delta was stored in the dropped commit_meta JSON blob. This migration
adds it as a dedicated nullable JSONB column so the symbol indexer can read it
back without losing fidelity on historical commits. New pushes write it directly;
historical rows remain NULL and fall back to snapshot diffing.

Revision ID: 0021
Revises: 0020
"""
from __future__ import annotations

from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects.postgresql import JSONB

revision = "0021"
down_revision = "0020"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.add_column(
        "musehub_commits",
        sa.Column("structured_delta", JSONB(), nullable=True),
    )


def downgrade() -> None:
    from sqlalchemy import text
    op.execute(text("ALTER TABLE musehub_commits DROP COLUMN IF EXISTS structured_delta"))