Revert "First pass at updating chat component page for a chatlas world"

This reverts commit 961c3a6.

Author: cpsievert

components/display-messages/chat/app-core.py

@@ -13,9 +13,9 @@ def server(input):
 
     # Define a callback to run when the user submits a message
     @chat.on_user_submit  # <<
-    async def handle_user_input(user_input: str):  # <<
+    async def _():  # <<
         # Simply echo the user's input back to them
-        await chat.append_message(f"You said: {user_input}")  # <<
+        await chat.append_message(f"You said: {chat.user_input()}")  # <<
 
 
 app = App(app_ui, server)

components/display-messages/chat/app-express.py

@@ -13,6 +13,6 @@
 
 # Define a callback to run when the user submits a message
 @chat.on_user_submit  # <<
-async def handle_user_input(user_input: str):  # <<
+async def _():  # <<
     # Simply echo the user's input back to them
-    await chat.append_message(f"You said: {user_input}")  # <<
+    await chat.append_message(f"You said: {chat.user_input()}")  # <<

components/display-messages/chat/app-preview-code.py

@@ -14,6 +14,6 @@
 
 # Define a callback to run when the user submits a message
 @chat.on_user_submit
-async def handle_user_input(user_input: str):
+async def _():
     # Append a response to the chat
-    await chat.append_message(f"You said: {user_input}")
+    await chat.append_message(f"You said: {chat.user_input()}")

components/display-messages/chat/app-preview.py

@@ -12,7 +12,7 @@
     """
     Hi! This is a simple Shiny `Chat` UI. Enter a message below and I will
     simply repeat it back to you. For more examples, see this
-    [folder of examples](https://github.com/posit-dev/py-shiny/tree/main/shiny/templates/chat).
+    [folder of examples](https://github.com/posit-dev/py-shiny/tree/main/examples/chat).
     """
 )
 
@@ -28,6 +28,11 @@
 
 # Define a callback to run when the user submits a message
 @chat.on_user_submit
-async def handle_user_input(user_input: str):
+async def _():
+    # Get the chat messages.
+    messages = chat.messages()
+    # Typically you'd pass messages to an LLM for response generation,
+    # but for this example, we'll just echo the user's input
+    user = messages[-1]["content"]
     # Append a response to the chat
-    await chat.append_message(f"You said: {user_input}")
+    await chat.append_message(f"You said: {user}")