Don't garbage collect input values when converting smart cell to code (#1781)

lib/livebook/session.ex

@@ -999,21 +999,22 @@ defmodule Livebook.Session do
         chunks = cell.chunks || [{0, byte_size(cell.source)}]
         chunk_count = length(chunks)
 
-        state = handle_operation(state, {:delete_cell, client_id, cell.id})
+        state =
+          for {{offset, size}, chunk_idx} <- Enum.with_index(chunks), reduce: state do
+            state ->
+              outputs = if(chunk_idx == chunk_count - 1, do: cell.outputs, else: [])
+              source = binary_part(cell.source, offset, size)
+              attrs = %{source: source, outputs: outputs}
+              cell_idx = index + chunk_idx
+              cell_id = Utils.random_id()
 
-        for {{offset, size}, chunk_idx} <- Enum.with_index(chunks), reduce: state do
-          state ->
-            outputs = if(chunk_idx == chunk_count - 1, do: cell.outputs, else: [])
-            source = binary_part(cell.source, offset, size)
-            attrs = %{source: source, outputs: outputs}
-            cell_idx = index + chunk_idx
-            cell_id = Utils.random_id()
+              handle_operation(
+                state,
+                {:insert_cell, client_id, section.id, cell_idx, :code, cell_id, attrs}
+              )
+          end
 
-            handle_operation(
-              state,
-              {:insert_cell, client_id, section.id, cell_idx, :code, cell_id, attrs}
-            )
-        end
+        handle_operation(state, {:delete_cell, client_id, cell.id})
       else
         _ -> state
       end

test/livebook/session_test.exs

@@ -198,6 +198,35 @@ defmodule Livebook.SessionTest do
                       {:insert_cell, _client_id, ^section_id, 1, :code, _id,
                        %{source: "chunk 2", outputs: [{1, {:text, "Hello"}}]}}}
     end
+
+    test "doesn't garbage collect input values" do
+      input = %{
+        ref: :input_ref,
+        id: "input1",
+        type: :text,
+        label: "Name",
+        default: "hey",
+        destination: :noop
+      }
+
+      smart_cell = %{
+        Notebook.Cell.new(:smart)
+        | kind: "text",
+          source: "content",
+          outputs: [{1, {:input, input}}]
+      }
+
+      section = %{Notebook.Section.new() | cells: [smart_cell]}
+      notebook = %{Notebook.new() | sections: [section]}
+
+      session = start_session(notebook: notebook)
+
+      Session.subscribe(session.id)
+
+      Session.convert_smart_cell(session.pid, smart_cell.id)
+
+      assert %{input_values: %{"input1" => "hey"}} = Session.get_data(session.pid)
+    end
   end
 
   describe "add_dependencies/2" do