BE-2: Enforce unique connector names per user and search space (idempotent migration)

surfsense_backend/alembic/versions/58_unique_connector_name_per_space_user.py

@@ -0,0 +1,53 @@
+"""
+Add unique constraint for (search_space_id, user_id, name) on search_source_connectors.
+
+Revision ID: 58
+Revises: 57
+Create Date: 2026-01-06 14:00:00.000000
+
+"""
+
+from collections.abc import Sequence
+from alembic import op
+
+revision: str = "58"
+down_revision: str | None = "57"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+from sqlalchemy import text
+
+def upgrade() -> None:
+    connection = op.get_bind()
+    constraint_exists = connection.execute(
+        text("""
+            SELECT 1 FROM information_schema.table_constraints
+            WHERE table_name='search_source_connectors'
+              AND constraint_type='UNIQUE'
+              AND constraint_name='uq_searchspace_user_connector_name'
+        """)
+    ).scalar()
+    if not constraint_exists:
+        op.create_unique_constraint(
+            "uq_searchspace_user_connector_name",
+            "search_source_connectors",
+            ["search_space_id", "user_id", "name"]
+        )
+
+def downgrade() -> None:
+    connection = op.get_bind()
+    constraint_exists = connection.execute(
+        text("""
+            SELECT 1 FROM information_schema.table_constraints
+            WHERE table_name='search_source_connectors'
+              AND constraint_type='UNIQUE'
+              AND constraint_name='uq_searchspace_user_connector_name'
+        """)
+    ).scalar()
+    if constraint_exists:
+        op.drop_constraint(
+            "uq_searchspace_user_connector_name",
+            "search_source_connectors",
+            type_="unique"
+        )
+