Replace broken multiselect with single-select + Add/Clear buttons

Gradio 6.5.1 multiselect dropdown is unreliable. Replaced with:
- Single-select dropdown to pick one line at a time
- "Add to party" button to add selected line to party list
- "Clear party" button to reset
- Visible "Party members" textbox showing current selections
This matches the backpack pattern used in Quest 2/4 which works reliably.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app.py

@@ -156,31 +156,40 @@ with demo:
         outputs=[C["q1_umap_plot"]],
     )
 
-    # Party selection via dropdown
-    def on_party_dropdown(selected_lines, state):
+    # Party selection via add / clear buttons
+    def _party_display_text(party):
+        if party:
+            text = f"Selected {len(party)} lines: " + ", ".join(party[:10])
+            if len(party) > 10:
+                text += f" ... +{len(party) - 10} more"
+            return text
+        return "None selected"
+
+    def on_add_to_party(selected_line, state):
         if state is None:
             state = AppState()
-        # Gradio 6.x multiselect may pass None, a single string, or a list
-        if selected_lines is None:
-            state.selected_party = []
-        elif isinstance(selected_lines, str):
-            state.selected_party = [selected_lines] if selected_lines else []
-        else:
-            state.selected_party = list(selected_lines)
-        if state.selected_party:
-            text = f"Selected {len(state.selected_party)} lines: " + ", ".join(state.selected_party[:10])
-            if len(state.selected_party) > 10:
-                text += f" ... +{len(state.selected_party) - 10} more"
-        else:
-            text = "None selected"
-        return text, state
+        if selected_line and selected_line not in state.selected_party:
+            state.selected_party.append(selected_line)
+        return _party_display_text(state.selected_party), state
+
+    def on_clear_party(state):
+        if state is None:
+            state = AppState()
+        state.selected_party = []
+        return "None selected", state
 
-    C["q1_party_dropdown"].change(
-        fn=on_party_dropdown,
+    C["q1_add_party_btn"].click(
+        fn=on_add_to_party,
         inputs=[C["q1_party_dropdown"], C["state"]],
         outputs=[C["q1_party_display"], C["state"]],
     )
 
+    C["q1_clear_party_btn"].click(
+        fn=on_clear_party,
+        inputs=[C["state"]],
+        outputs=[C["q1_party_display"], C["state"]],
+    )
+
     def on_compare_click(state):
         fig, _ = on_compare_party(state, DATA)
         return gr.Plot(value=fig, visible=True)

ui/quest1.py

@@ -166,8 +166,8 @@ def build_quest1(line_choices: list[str] | None = None):
     that ``layout.py`` can prefix them with ``q1_`` and ``app.py`` can
     wire callbacks without changes.
 
-    Keys: tab, color_radio, umap_plot, party_dropdown, party_display,
-          compare_btn, comparison_plot
+    Keys: tab, color_radio, umap_plot, party_dropdown, add_party_btn,
+          clear_party_btn, party_display, compare_btn, comparison_plot
     """
     with gr.Tab("Genetic Landscape", id="quest1") as tab:
 
@@ -221,11 +221,18 @@ def build_quest1(line_choices: list[str] | None = None):
         with gr.Row():
             party_dropdown = gr.Dropdown(
                 choices=line_choices or [],
-                label="Select lines to compare (party members)",
-                multiselect=True,
+                label="Pick a line to add",
                 interactive=True,
                 filterable=True,
-                allow_custom_value=False,
+            )
+            add_party_btn = gr.Button(
+                "Add to party",
+                variant="secondary",
+            )
+            clear_party_btn = gr.Button(
+                "Clear party",
+                variant="stop",
+                size="sm",
             )
             compare_btn = gr.Button(
                 "Compare",
@@ -233,11 +240,11 @@ def build_quest1(line_choices: list[str] | None = None):
             )
 
         party_display = gr.Textbox(
-            label="Selected party",
+            label="Party members",
             interactive=False,
             value="None selected",
             lines=1,
-            visible=False,
+            visible=True,
         )
 
         comparison_plot = gr.Plot(label="Comparison", visible=False)
@@ -262,6 +269,8 @@ def build_quest1(line_choices: list[str] | None = None):
         "color_radio": color_radio,
         "umap_plot": umap_plot,
         "party_dropdown": party_dropdown,
+        "add_party_btn": add_party_btn,
+        "clear_party_btn": clear_party_btn,
         "party_display": party_display,
         "compare_btn": compare_btn,
         "comparison_plot": comparison_plot,