feat(automations): migrate automation_trigger_type enum to add event

surfsense_backend/alembic/versions/147_add_event_to_automation_trigger_type.py

@@ -0,0 +1,47 @@
+"""Add 'event' to automation_trigger_type enum
+
+Revision ID: 147
+Revises: 146
+Create Date: 2026-05-29
+
+Adds the ``event`` value to the ``automation_trigger_type`` enum so automations
+can be triggered by published domain events, alongside the existing
+``schedule`` triggers.
+"""
+
+from collections.abc import Sequence
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "147"
+down_revision: str | None = "146"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+ENUM_NAME = "automation_trigger_type"
+NEW_VALUE = "event"
+
+
+def upgrade() -> None:
+    """Safely add 'event' to automation_trigger_type enum if missing."""
+    op.execute(
+        f"""
+    DO $$
+    BEGIN
+        IF NOT EXISTS (
+            SELECT 1 FROM pg_type t
+            JOIN pg_enum e ON t.oid = e.enumtypid
+            WHERE t.typname = '{ENUM_NAME}' AND e.enumlabel = '{NEW_VALUE}'
+        ) THEN
+            ALTER TYPE {ENUM_NAME} ADD VALUE '{NEW_VALUE}';
+        END IF;
+    END
+    $$;
+    """
+    )
+
+
+def downgrade() -> None:
+    """No-op: PostgreSQL does not support removing enum values."""
+    pass