diag: print checkpoints + visible loading banner; expose errors to stderr

streamlit_app.py

@@ -2,8 +2,11 @@ import sys, os, traceback
 from pathlib import Path
 import streamlit as st
 
-# ── 1. Page config fires immediately so the browser gets a live response
-#       before the 10-30 s ML imports below.
+print("[SpindleFlow] wrapper starting", flush=True)
+
+_root = Path(__file__).resolve().parent
+
+# Page config fires before anything else so the browser gets a live response.
 st.set_page_config(
     page_title="SpindleFlow RL",
     page_icon="⚡",
@@ -11,30 +14,36 @@ st.set_page_config(
     initial_sidebar_state="collapsed",
 )
 
-# ── 2. Silence the duplicate set_page_config call inside demo/streamlit_app.py
-#       (it also has one at module level — would raise StreamlitAPIException).
+# Show a visible loading message while the heavy ML imports run (~20-30 s).
+_banner = st.empty()
+_banner.info("⏳ Loading SpindleFlow RL — first load takes ~30 s on CPU…")
+
+# Silence the duplicate set_page_config inside demo/streamlit_app.py.
 _real_spc = st.set_page_config
 st.set_page_config = lambda *a, **kw: None
 
-# ── 3. Make env.*, reward.*, agents.* and orchestrator_widget importable.
-_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))
 
-# ── 4. Run demo/streamlit_app.py exactly as __main__.
-#       Its st.set_page_config() call is now a no-op; main() draws the UI.
 _demo = _root / "demo" / "streamlit_app.py"
+print(f"[SpindleFlow] running exec on {_demo}", flush=True)
+
 try:
     exec(
         compile(_demo.read_text(encoding="utf-8"), str(_demo), "exec"),
         {"__file__": str(_demo), "__name__": "__main__"},
     )
+    print("[SpindleFlow] exec completed OK", flush=True)
+    _banner.empty()
 except SystemExit:
-    pass
+    _banner.empty()
 except Exception as exc:
+    print(f"[SpindleFlow] ERROR: {exc}", file=sys.stderr, flush=True)
+    traceback.print_exc(file=sys.stderr)
+    _banner.empty()
     st.error(f"SpindleFlow failed to load: {exc}")
     st.code(traceback.format_exc())
 finally:
-    st.set_page_config = _real_spc   # restore for subsequent Streamlit re-runs
+    st.set_page_config = _real_spc