fix: use exec() wrapper — eliminates double set_page_config crash

streamlit_app.py

@@ -1,39 +1,25 @@
-import streamlit as st
 import sys, os, traceback
 from pathlib import Path
 
-# Set page config immediately so the browser gets a response before the
-# heavy ML imports below.  demo/streamlit_app.py also calls set_page_config
-# at module level — we monkey-patch it to a no-op so the duplicate call
-# (on first import) doesn't raise a StreamlitAPIException.
-st.set_page_config(
-    page_title="SpindleFlow RL",
-    page_icon="⚡",
-    layout="wide",
-    initial_sidebar_state="collapsed",
-)
-_orig_spc = st.set_page_config
-st.set_page_config = lambda *a, **kw: None   # silence double-call from demo
-
-root = Path(__file__).resolve().parent
-demo_dir = root / "demo"
-for p in (str(root), str(demo_dir)):
-    if p not in sys.path:
-        sys.path.insert(0, p)
-os.chdir(str(root))
-
-
-@st.cache_resource(show_spinner="Loading SpindleFlow RL…")
-def _load_app():
-    """Cache the demo module so the 10–20 s ML import only happens once."""
-    import demo.streamlit_app as _app   # noqa: PLC0415
-    return _app
+# Make env.*, reward.*, agents.* (from repo root) and orchestrator_widget
+# (from demo/) importable before demo/streamlit_app.py starts.
+_root = Path(__file__).resolve().parent
+for _p in (str(_root), str(_root / "demo")):
+    if _p not in sys.path:
+        sys.path.insert(0, _p)
+os.chdir(str(_root))
 
+import streamlit as st   # needed only for the error fallback below
 
+_demo = _root / "demo" / "streamlit_app.py"
 try:
-    st.set_page_config = _orig_spc      # restore before main() uses st.*
-    _app = _load_app()
-    _app.main()
+    # Run demo/streamlit_app.py exactly as if it were the entry-point script.
+    # __file__ must point to the demo file so its own Path(__file__) logic
+    # resolves paths correctly (e.g. demo/assets, orchestrator_widget).
+    exec(
+        compile(_demo.read_text(encoding="utf-8"), str(_demo), "exec"),
+        {"__file__": str(_demo), "__name__": "__main__"},
+    )
 except SystemExit:
     pass
 except Exception as exc: