Hide the selected-route transcript row when the header badge already carries it

Every assistant turn rendered a 'Using <route>' status row that repeats
the route badge in the turn header, so a restored session read as a
column of duplicate route chips. Keep the row only when it adds
information: the header has no route attribution, the selected route
differs from the turn's final model, or a later mid-turn switch makes
the starting route part of the story.

frontend-modern/src/components/AI/Chat/MessageItem.tsx

@@ -304,8 +304,21 @@ export const MessageItem: Component<MessageItemProps> = (props) => {
         return !!evt.pendingTool;
       case 'tool_cancel':
         return !!evt.toolCancel;
-      case 'model_switch':
-        return !!evt.model?.trim();
+      case 'model_switch': {
+        if (!evt.model?.trim()) return false;
+        if (!isSelectedModelRouteEvent(evt)) return true;
+        // A plain selected-route row repeats the route badge already shown in
+        // the turn header. Keep it only when it adds information: the header
+        // has no route, the route differs from the turn's final model, or a
+        // later switch makes the starting route part of the turn's story.
+        const hasRouteSwitch = (props.message.streamEvents || []).some(
+          (event) =>
+            event.type === 'model_switch' &&
+            !!event.model?.trim() &&
+            !isSelectedModelRouteEvent(event),
+        );
+        return hasRouteSwitch || !props.message.model || evt.model !== props.message.model;
+      }
       case 'approval':
         return !!evt.approval;
       case 'question':

frontend-modern/src/components/AI/Chat/__tests__/MessageItem.test.tsx

@@ -1170,6 +1170,70 @@ describe('MessageItem', () => {
       ).toHaveTextContent('Using Qwen 3.7 Plus via OpenRouter');
     });
 
+    it('hides the selected-route row when the turn header badge already shows the same route', () => {
+      const events: StreamDisplayEvent[] = [
+        {
+          type: 'model_switch',
+          model: 'openrouter:qwen/qwen3.7-plus',
+          modelEvent: 'selected',
+        },
+      ];
+
+      render(() => (
+        <MessageItem
+          message={makeMessage({
+            role: 'assistant',
+            model: 'openrouter:qwen/qwen3.7-plus',
+            streamEvents: events,
+          })}
+          getModelRouteLabel={(model) =>
+            model === 'openrouter:qwen/qwen3.7-plus' ? 'Qwen 3.7 Plus via OpenRouter' : model
+          }
+          {...makeHandlers()}
+        />
+      ));
+
+      expect(
+        screen.queryByRole('status', { name: 'Assistant model route selected' }),
+      ).not.toBeInTheDocument();
+      // The route is still visible exactly once, in the header badge.
+      expect(screen.getByText('Qwen 3.7 Plus via OpenRouter')).toBeInTheDocument();
+    });
+
+    it('keeps the selected-route row when a later switch makes it part of the turn story', () => {
+      const events: StreamDisplayEvent[] = [
+        {
+          type: 'model_switch',
+          model: 'openrouter:qwen/qwen3.7-plus',
+          modelEvent: 'selected',
+        },
+        {
+          type: 'model_switch',
+          failedModel: 'openrouter:qwen/qwen3.7-plus',
+          model: 'gemini:gemini-3.1-flash-lite',
+        },
+      ];
+
+      render(() => (
+        <MessageItem
+          message={makeMessage({
+            role: 'assistant',
+            model: 'gemini:gemini-3.1-flash-lite',
+            streamEvents: events,
+          })}
+          getModelRouteLabel={(model) => model}
+          {...makeHandlers()}
+        />
+      ));
+
+      expect(
+        screen.getByRole('status', { name: 'Assistant model route selected' }),
+      ).toBeInTheDocument();
+      expect(
+        screen.getByRole('status', { name: 'Assistant model route changed' }),
+      ).toBeInTheDocument();
+    });
+
     it('does not render request-start progress as a transcript row next to selected model route evidence (footer-owned)', () => {
       const events: StreamDisplayEvent[] = [
         {