M41: harden trust boundaries and delivery

backend/alembic/versions/4f2b9c8d7e61_unique_open_quality_condition.py

@@ -0,0 +1,27 @@
+"""enforce one open issue per detected condition
+
+Revision ID: 4f2b9c8d7e61
+Revises: 0a4c1d2e3f5b
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+revision = "4f2b9c8d7e61"
+down_revision = "0a4c1d2e3f5b"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_index(
+        "uq_data_quality_one_open_condition",
+        "data_quality_issues",
+        ["rule_type", "entity_type", "entity_id"],
+        unique=True,
+        postgresql_where=sa.text("status = 'open'"),
+    )
+
+
+def downgrade() -> None:
+    op.drop_index("uq_data_quality_one_open_condition", table_name="data_quality_issues")