draft(pky-py): Use extended task

pkg-py/src/querychat/querychat.py

@@ -617,19 +617,23 @@ async def query(query: str):
     chat.register_tool(update_dashboard)
     chat.register_tool(query)
 
-    # Add greeting if provided
-    if greeting and any(len(g) > 0 for g in greeting.split("\n")):
-        # Display greeting in chat UI
-        pass
-    else:
-        # Generate greeting using the chat model
-        pass
+    @reactive.extended_task
+    async def append_stream(chat_obj: chatlas.Chat, user_input: str):
+        stream = await chat_obj.stream_async(user_input, echo="none")
+        await chat_ui.append_message_stream(stream)
 
     # Handle user input
     @chat_ui.on_user_submit
-    async def _(user_input: str):
-        stream = await chat.stream_async(user_input, echo="none")
-        await chat_ui.append_message_stream(stream)
+    def _(user_input: str):
+        append_stream(chat, user_input)
+
+    @reactive.effect
+    async def _():
+        if append_stream.status() == "error":
+            await chat_ui.append_message(
+                "An error occurred while processing your input. "
+                f"Error: {append_stream.result()}.",
+            )
 
     @reactive.effect
     async def greet_on_startup():
@@ -642,5 +646,18 @@ async def greet_on_startup():
             )
             await chat_ui.append_message_stream(stream)
 
+    @reactive.calc
+    def current_query_rv():
+        return current_query.get()
+
+    @reactive.calc
+    def current_title_rv():
+        return current_title.get()
+
     # Return the interface for other components to use
-    return QueryChat(chat, current_query.get, current_title.get, filtered_df)
+    return QueryChat(
+        chat,
+        current_query_rv,
+        current_title_rv,
+        filtered_df,
+    )

pkg-r/DESCRIPTION

@@ -21,6 +21,7 @@ Imports:
     ellmer (>= 0.3.0),
     htmltools,
     lifecycle,
+    promises,
     purrr,
     rlang,
     shiny,

pkg-r/NEWS.md

@@ -17,3 +17,5 @@
   * the `querychat.client` R option, which can be any of the above options,
   * the `QUERYCHAT_CLIENT` environment variable, which should be a provider-model string,
   * or the default model from `ellmer::chat_openai()`.
+
+* `querychat_server()` now uses a `shiny::ExtendedTask` for streaming the chat response, which allows the dashboard to update and remain responsive while the chat response is streaming in. (#63)

pkg-r/R/querychat.R

@@ -285,13 +285,22 @@ querychat_server <- function(id, querychat_config) {
       )
     }
 
-    # Handle user input
+    append_stream_task <- shiny::ExtendedTask$new(
+      function(client, user_input) {
+        stream <- client$stream_async(
+          user_input,
+          stream = "content"
+        )
+
+        p <- promises::promise_resolve(stream)
+        promises::then(p, function(stream) {
+          shinychat::chat_append("chat", stream)
+        })
+      }
+    )
+
     shiny::observeEvent(input$chat_user_input, {
-      # Add user message to the chat history
-      shinychat::chat_append(
-        "chat",
-        chat$stream_async(input$chat_user_input, stream = "content")
-      )
+      append_stream_task$invoke(chat, input$chat_user_input)
     })
 
     list(