Refactor player selection handling in Handbuilder tab of Streamlit app to support multiple selections, allowing users to add and remove players from the lineup more intuitively. Update selection state management to improve data accuracy and user experience during lineup updates.

src/streamlit_app.py

@@ -619,17 +619,28 @@ if selected_tab == 'Handbuilder':
         event = st.dataframe(
             st.session_state['player_select_df'].style.background_gradient(axis=0).background_gradient(cmap='RdYlGn').background_gradient(cmap='RdYlGn_r', subset=['Salary', 'Own']).format(precision=2),
             on_select="rerun",
-            selection_mode=["single-row"],
+            selection_mode="multiple",  # Changed to multiple selection
             key="player_select_dataframe",
             height=500,
             hide_index=True
         )
-        # If a row is selected, add that player to the lineup and reset selection
-        if event and "rows" in event.selection and len(event.selection["rows"]) > 0:
-            idx = event.selection["rows"][0]
+        
+        # Get current selection state
+        current_selection = set()
+        if event and "rows" in event.selection:
+            current_selection = set(event.selection["rows"])
+        
+        # Get previous selection state from session
+        previous_selection = set(st.session_state.get('previous_player_selection', []))
+        
+        # Find newly selected and newly unselected players
+        newly_selected = current_selection - previous_selection
+        newly_unselected = previous_selection - current_selection
+        
+        # Handle newly selected players (add to lineup)
+        for idx in newly_selected:
             player_row = st.session_state['player_select_df'].iloc[[idx]]
             eligible_positions = re.split(r'[/, ]+', player_row['Position'].iloc[0])
-            # Find the first eligible slot that is not full
             slot_to_fill = None
 
             for slot in ['QB', 'RB', 'WR', 'TE', 'UTIL', 'DST']:
@@ -645,14 +656,22 @@ if selected_tab == 'Handbuilder':
             if slot_to_fill is not None:
                 # Avoid duplicates
                 if not player_row['Player'].iloc[0] in st.session_state['handbuilder_lineup']['Player'].values:
-                    # Add the slot info
                     player_row = player_row.assign(Slot=slot_to_fill)
                     st.session_state['handbuilder_lineup'] = pd.concat(
                         [st.session_state['handbuilder_lineup'], player_row[['Player', 'Position', 'Team', 'Salary', 'Median', '2x%', 'Own', 'Slot']]],
                         ignore_index=True
                     )
-                    event.selection = {"rows": []}
-                    st.rerun()
+        
+        # Handle newly unselected players (remove from lineup)
+        for idx in newly_unselected:
+            player_to_remove = st.session_state['player_select_df'].iloc[idx]['Player']
+            if player_to_remove in st.session_state['handbuilder_lineup']['Player'].values:
+                st.session_state['handbuilder_lineup'] = st.session_state['handbuilder_lineup'][
+                    st.session_state['handbuilder_lineup']['Player'] != player_to_remove
+                ]
+        
+        # Store current selection for next comparison
+        st.session_state['previous_player_selection'] = list(current_selection)
 
     with handbuilder_lineup_build_column:
         st.subheader("Lineup Build")
@@ -697,28 +716,13 @@ if selected_tab == 'Handbuilder':
 
         st.session_state['lineup_display_df'] = pd.DataFrame(display_rows, columns=display_columns)
 
-        # Show the lineup table with single-row selection for removal
-        event_remove = st.dataframe(
+        # Show the lineup table as a static display (no selection needed)
+        st.dataframe(
             st.session_state['lineup_display_df'].style.background_gradient(axis=0).background_gradient(cmap='RdYlGn', subset=['Median']).background_gradient(cmap='RdYlGn_r', subset=['Salary', 'Own']).format(precision=2),
-            on_select="rerun",
-            selection_mode=["single-row"],
-            key="lineup_remove_dataframe",
             height=445,
             hide_index=True
         )
 
-        # If a row is selected and not blank, remove that player from the lineup
-        if event_remove and "rows" in event_remove.selection and len(event_remove.selection["rows"]) > 0:
-            idx = event_remove.selection["rows"][0]
-            player_to_remove = st.session_state['lineup_display_df'].iloc[idx]['Player']
-            slot_to_remove = st.session_state['lineup_display_df'].iloc[idx]['Slot']
-            if player_to_remove:  # Only remove if not blank
-                st.session_state['handbuilder_lineup'] = filled_lineup[
-                    ~((filled_lineup['Player'] == player_to_remove) & (filled_lineup['Slot'] == slot_to_remove))
-                ]
-                event_remove.selection = {"rows": []}
-                st.rerun()
-
         # --- SUMMARY ROW ---
         if not filled_lineup.empty:
             total_salary = filled_lineup['Salary'].sum()