"""fc3a: unique(source.artist_id, source.platform, source.url)

Revision ID: 0010
Revises: 0009
Create Date: 2026-05-20

Enforces FC-3a's dedup invariant at the DB level. No backfill — no
existing rows are expected to collide; if they do the migration will
fail loudly (intended).
"""
from typing import Sequence, Union

from alembic import op

revision: str = "0010"
down_revision: Union[str, None] = "0009"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.create_unique_constraint(
        "uq_source_artist_platform_url",
        "source",
        ["artist_id", "platform", "url"],
    )


def downgrade() -> None:
    op.drop_constraint(
        "uq_source_artist_platform_url", "source", type_="unique"
    )
