Implement lineup management in Handbuilder tab of app.py by introducing a session state for the lineup, allowing players to be added without duplicates. Update summary calculations to reflect the current lineup and add a "Clear Lineup" button for user convenience, enhancing overall functionality and user experience.

app.py

@@ -802,9 +802,6 @@ with tab3:
 with tab4:
     st.header("Handbuilder")
 
-    if st.button("Clear Data", key='clear_handbuild'):
-        st.rerun()
-
     # --- TEAM FILTER UI ---
     all_teams = sorted(dk_roo['Team'].unique())
     st.markdown("**Toggle teams to include:**")
@@ -827,34 +824,48 @@ with tab4:
     else:
         player_select_df = dk_roo[['Player', 'Position', 'Team', 'Salary', 'Median', 'Order', 'Hand', 'Own%']].copy()
 
+    # --- LINEUP STATE ---
+    if 'handbuilder_lineup' not in st.session_state:
+        st.session_state['handbuilder_lineup'] = pd.DataFrame(columns=['Player', 'Team', 'Salary', 'Median', 'Own%'])
+
     col1, col2 = st.columns([1, 2])
     with col2:
         st.subheader("Player Select")
         event = st.dataframe(
             player_select_df,
             on_select="rerun",
-            selection_mode=["multi-row"]
+            selection_mode=["single-row"]
         )
 
-    # Get selected rows (if any)
-    selected_indices = event.selection["rows"] if event and "rows" in event.selection else []
-    select_players_disp = player_select_df.iloc[selected_indices][['Player', 'Team', 'Salary', 'Median', 'Own%']]
+        # If a row is selected, add that player to the lineup
+        if event and "rows" in event.selection and len(event.selection["rows"]) > 0:
+            idx = event.selection["rows"][0]
+            player_row = player_select_df.iloc[[idx]][['Player', 'Team', 'Salary', 'Median', 'Own%']]
+            # Avoid duplicates
+            if not player_row['Player'].iloc[0] in st.session_state['handbuilder_lineup']['Player'].values:
+                st.session_state['handbuilder_lineup'] = pd.concat(
+                    [st.session_state['handbuilder_lineup'], player_row],
+                    ignore_index=True
+                )
+            # Rerun to reset selection
+            st.rerun()
 
     with col1:
         st.subheader("Lineup")
         st.dataframe(
-            select_players_disp,
+            st.session_state['handbuilder_lineup'],
             use_container_width=True,
             height=300,
             hide_index=True
         )
 
         # --- SUMMARY ROW ---
-        if not select_players_disp.empty:
-            total_salary = select_players_disp['Salary'].sum()
-            total_median = select_players_disp['Median'].sum()
-            total_own = select_players_disp['Own%'].sum()
-            most_common_team = select_players_disp['Team'].mode()[0] if not select_players_disp['Team'].mode().empty else ""
+        lineup = st.session_state['handbuilder_lineup']
+        if not lineup.empty:
+            total_salary = lineup['Salary'].sum()
+            total_median = lineup['Median'].sum()
+            total_own = lineup['Own%'].sum()
+            most_common_team = lineup['Team'].mode()[0] if not lineup['Team'].mode().empty else ""
 
             summary_row = pd.DataFrame({
                 'Player': ['TOTAL'],
@@ -863,11 +874,16 @@ with tab4:
                 'Median': [total_median],
                 'Own%': [total_own]
             })
-            summary_row = summary_row[select_players_disp.columns]
+            summary_row = summary_row[lineup.columns]
 
             st.dataframe(
                 summary_row,
                 use_container_width=True,
                 height=50,
                 hide_index=True
-            )
+            )
+
+    # Optionally, add a button to clear the lineup
+    if st.button("Clear Lineup", key='clear_lineup'):
+        st.session_state['handbuilder_lineup'] = pd.DataFrame(columns=['Player', 'Team', 'Salary', 'Median', 'Own%'])
+        st.rerun()