fix(webui): only highlight actual model fallbacks

webui/src/components/thread/ThreadShell.tsx

@@ -959,7 +959,7 @@ export function ThreadShell({
     setFallbackModelName(null);
     return client.onChat(chatId, (event) => {
       if (event.event !== "turn_model_updated") return;
-      setFallbackModelName(event.model_name);
+      setFallbackModelName(event.is_fallback ? event.model_name : null);
     });
   }, [chatId, client]);
 

webui/src/lib/types.ts

@@ -1313,6 +1313,7 @@ export type InboundEvent =
       chat_id: string;
       model_name: string;
       model_preset?: string | null;
+      is_fallback?: boolean;
     }
   | ({
       event: "turn_end";

webui/src/tests/nanobot-client.test.ts

@@ -1724,6 +1724,7 @@ describe("NanobotClient", () => {
       chat_id: "chat-a",
       model_name: "deepseek/deepseek-chat",
       model_preset: "Deep Research",
+      is_fallback: true,
     });
 
     expect(chatHandler).toHaveBeenCalledWith({
@@ -1731,6 +1732,7 @@ describe("NanobotClient", () => {
       chat_id: "chat-a",
       model_name: "deepseek/deepseek-chat",
       model_preset: "Deep Research",
+      is_fallback: true,
     });
   });
 

webui/src/tests/thread-shell.test.tsx

@@ -696,7 +696,7 @@ describe("ThreadShell", () => {
     expect(screen.queryByRole("button", { name: "Model not configured" })).not.toBeInTheDocument();
   });
 
-  it("highlights the configured model badge without replacing the preset label", async () => {
+  it("only highlights fallback model updates without replacing the preset label", async () => {
     const client = makeClient();
     render(wrap(
       client,
@@ -715,11 +715,23 @@ describe("ThreadShell", () => {
     expect(configuredBadge).toHaveClass("composer-model-badge");
     expect(configuredBadge).not.toHaveAttribute("data-fallback");
 
+    act(() => {
+      client._emitChat("fallback-model", {
+        event: "turn_model_updated",
+        chat_id: "fallback-model",
+        model_name: "openai-codex/gpt-5.5",
+        is_fallback: false,
+      });
+    });
+
+    expect(configuredBadge).not.toHaveAttribute("data-fallback");
+
     act(() => {
       client._emitChat("fallback-model", {
         event: "turn_model_updated",
         chat_id: "fallback-model",
         model_name: "deepseek/deepseek-chat",
+        is_fallback: true,
       });
     });