US06-04: Plan and Execute Safe Restores (#80)

migrations/versions/0014_restore_plans.py

@@ -0,0 +1,37 @@
+"""Restore plans and archive divergence (US06-04).
+
+Revision ID: 0014_restore_plans
+Revises: 0013_protected_thumbnails
+Create Date: 2026-08-16
+
+Restore reuses the archive plan and journal tables: the crash-safe question is the
+same one in the opposite direction (copy, verify, publish, register), so the rows
+gain a ``direction`` instead of a parallel pair of tables. ``archive_divergent_at``
+records the moment an archived copy was proven to hold bytes that are not the ones
+the database recorded — a restore must never silently accept a different file.
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+revision = "0014_restore_plans"
+down_revision = "0013_protected_thumbnails"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    for table in ("archive_plans", "archive_operations"):
+        op.add_column(
+            table,
+            sa.Column("direction", sa.String(), nullable=False, server_default="archive"),
+        )
+    op.add_column(
+        "assets", sa.Column("archive_divergent_at", sa.DateTime(timezone=True), nullable=True)
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("assets", "archive_divergent_at")
+    for table in ("archive_plans", "archive_operations"):
+        op.drop_column(table, "direction")