refactor(subscribe): deduplicate duplicate media records

database/versions/a7d9e2c4f6b1_3_0_23.py

@@ -0,0 +1,48 @@
+"""3.0.23 增加订阅下载交付目标范围。
+
+Revision ID: a7d9e2c4f6b1
+Revises: f3c8a1d6b2e9
+Create Date: 2026-09-01
+"""
+
+# Alembic 的 op 是运行期代理，静态分析无法看到实际操作方法。
+# pylint: disable=no-member
+
+import sqlalchemy as sa
+from alembic import op
+
+revision = "a7d9e2c4f6b1"
+down_revision = "f3c8a1d6b2e9"
+branch_labels = None
+depends_on = None
+
+_TABLE = "subscriptiondownloadsubmission"
+
+
+def _column_names() -> set[str]:
+    """返回当前订阅下载提交列名集合。"""
+    inspector = sa.inspect(op.get_bind())
+    if _TABLE not in set(inspector.get_table_names()):
+        return set()
+    return {column["name"] for column in inspector.get_columns(_TABLE)}
+
+
+def upgrade() -> None:
+    """为存量提交增加兼容交付范围，新键会写入实际下载目标。"""
+    columns = _column_names()
+    if columns and "delivery_scope" not in columns:
+        op.add_column(
+            _TABLE,
+            sa.Column(
+                "delivery_scope",
+                sa.Text(),
+                nullable=False,
+                server_default="legacy",
+            ),
+        )
+
+
+def downgrade() -> None:
+    """移除交付范围字段，保留原提交账本与唯一键。"""
+    if "delivery_scope" in _column_names():
+        op.drop_column(_TABLE, "delivery_scope")