Update util/session_state.py

util/session_state.py

@@ -6,4 +6,11 @@ def current_uid() -> Optional[str]:
     """Return the signed-in user's id/email from session, if any."""
     return st.session_state.get("uid")
 
+def get_current_uid() -> str:
+    """Get current user ID with validation. Raises error if not logged in."""
+    uid = current_uid()
+    if not uid:
+        st.error("Please log in to continue.")
+        st.stop()
+    return uid