01-Streamlit-Template is broken on newer Streamlit version

[bechbd]

The sample here https://github.com/strands-agents/samples/tree/main/04-UX-demos/01-streamlit-template is broken when working with app_streaming.py and the current streamlit version.

I think something with one of the backwards incompatible changes might have broken it. When I run it with the version of Strands in the requirements.txt, but if I upgrade it to the newest version (1.4.0) then I get a variety of errors about session state not being initialized.

AttributeError: st.session_state has no attribute "details_placeholder". Did you forget to initialize it? More info: https://docs.streamlit.io/develop/concepts/architecture/session-state#initialization

[melrubino]

I have run into the same issue, the newer strands version breaks in this example that uses a custom callback handler to display streaming responses.

The callback handler updates streamlit context within the function. However, I believe there was a change in strands threading with tools that causes a different thread (and thus streamlit context) to that executes the callback handler, not the same one that the display is showing.