fix: Enable sorting of chat inputs to improve UI message speed (#4480)

src/backend/base/langflow/graph/graph/base.py

@@ -2006,7 +2006,8 @@ class Graph:
 
         vertices_layers = self.layered_topological_sort(vertices)
         vertices_layers = self.sort_by_avg_build_time(vertices_layers)
-        # vertices_layers = self.sort_chat_inputs_first(vertices_layers)
+        # Sort the chat inputs first to speed up sending the User message to the UI
+        vertices_layers = self.sort_chat_inputs_first(vertices_layers)
         # Now we should sort each layer in a way that we make sure
         # vertex V does not depend on vertex V+1
         vertices_layers = self.sort_layer_by_dependency(vertices_layers)

src/backend/tests/unit/test_chat_endpoint.py

@@ -73,7 +73,7 @@ async def consume_and_assert_stream(r):
             assert parsed["event"] == "vertices_sorted"
             ids = parsed["data"]["ids"]
             ids.sort()
-            assert ids == ["ChatInput-CIGht", "Memory-amN4Z"]
+            assert ids == ["ChatInput-CIGht"]
 
             to_run = parsed["data"]["to_run"]
             to_run.sort()

src/backend/tests/unit/test_endpoints.py

@@ -257,7 +257,7 @@ async def test_get_vertices(client, added_flow_webhook_test, logged_in_headers):
     # The important part is before the - (ConversationBufferMemory, PromptTemplate, ChatOpenAI, LLMChain)
     ids = [_id.split("-")[0] for _id in response.json()["ids"]]
 
-    assert set(ids) == {"Webhook", "ChatInput"}
+    assert set(ids) == {"ChatInput"}
 
 
 async def test_build_vertex_invalid_flow_id(client, logged_in_headers):