Fix node deletion

app/models/node_parameter.rb

@@ -8,6 +8,8 @@ class NodeParameter < ApplicationRecord
 
   validate :only_one_value_present
 
+  before_destroy :destroy_value_objects
+
   def to_grpc
     param = Tucana::Shared::NodeParameter.new(
       database_id: id,
@@ -35,4 +37,9 @@ def only_one_value_present
 
     errors.add(:value, 'Only one of literal_value, reference_value, or function_value must be present')
   end
+
+  def destroy_value_objects
+    reference_value.destroy if reference_value.present?
+    function_value.destroy if function_value.present?
+  end
 end

app/services/namespaces/projects/flows/update_service.rb

@@ -197,7 +197,7 @@ def update_node_parameters(t, current_node, current_node_input, all_nodes)
 
               db_parameters[index].function_value = node[:node]
             else
-              db_parameters[index].function_value = nil
+              db_parameters[index].function_value&.destroy
             end
 
             if parameter.value.reference_value.present?
@@ -227,7 +227,7 @@ def update_node_parameters(t, current_node, current_node_input, all_nodes)
                 reference_paths: reference_paths
               )
             else
-              db_parameters[index].reference_value = nil
+              db_parameters[index].reference_value&.destroy
             end
 
             next if db_parameters[index].valid?

db/migrate/20260213230904_make_node_function_constraints_deferrable.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+class MakeNodeFunctionConstraintsDeferrable < Code0::ZeroTrack::Database::Migration[1.0]
+  def change
+    remove_foreign_key :reference_values,
+                       :node_functions,
+                       on_delete: :restrict
+
+    add_foreign_key :reference_values,
+                    :node_functions,
+                    deferrable: :deferred
+
+    remove_foreign_key :node_functions,
+                       :node_functions,
+                       column: :next_node_id,
+                       on_delete: :restrict
+
+    add_foreign_key :node_functions,
+                    :node_functions,
+                    column: :next_node_id,
+                    deferrable: :deferred
+  end
+end

db/schema_migrations/20260213230904

@@ -0,0 +1 @@
+501fc65ab83b207de468a27d7e65c82b75fcf7f55def5678bd84e666b16dbd7f

db/structure.sql

@@ -1343,7 +1343,7 @@ ALTER TABLE ONLY node_functions
     ADD CONSTRAINT fk_rails_8615bd0635 FOREIGN KEY (flow_id) REFERENCES flows(id) ON DELETE CASCADE;
 
 ALTER TABLE ONLY reference_values
-    ADD CONSTRAINT fk_rails_8b9d8f68cc FOREIGN KEY (node_function_id) REFERENCES node_functions(id) ON DELETE RESTRICT;
+    ADD CONSTRAINT fk_rails_8b9d8f68cc FOREIGN KEY (node_function_id) REFERENCES node_functions(id) DEFERRABLE INITIALLY DEFERRED;
 
 ALTER TABLE ONLY data_type_identifiers
     ADD CONSTRAINT fk_rails_8d8385e8ec FOREIGN KEY (runtime_id) REFERENCES runtimes(id) ON DELETE CASCADE;
@@ -1415,4 +1415,4 @@ ALTER TABLE ONLY flow_type_settings
     ADD CONSTRAINT fk_rails_f6af7d8edf FOREIGN KEY (flow_type_id) REFERENCES flow_types(id) ON DELETE CASCADE;
 
 ALTER TABLE ONLY node_functions
-    ADD CONSTRAINT fk_rails_fbc91a3407 FOREIGN KEY (next_node_id) REFERENCES node_functions(id) ON DELETE RESTRICT;
+    ADD CONSTRAINT fk_rails_fbc91a3407 FOREIGN KEY (next_node_id) REFERENCES node_functions(id) DEFERRABLE INITIALLY DEFERRED;