fix(webui): only highlight actual model fallbacks

nanobot/bus/outbound_events.py

@@ -100,6 +100,7 @@ class TurnModelUpdatedEvent(OutboundEvent):
     model: str
     model_preset: str | None = None
     context_window_tokens: int | None = None
+    is_fallback: bool = False
 
 
 def outbound_message_for_event(

nanobot/channels/websocket/runtime.py

@@ -1685,6 +1685,7 @@ class WebSocketChannel(BaseChannel):
                     model_name=event.model,
                     model_preset=event.model_preset,
                     context_window_tokens=event.context_window_tokens,
+                    is_fallback=event.is_fallback,
                 )
             return
         if isinstance(event, UserInputEvent):
@@ -2102,6 +2103,7 @@ class WebSocketChannel(BaseChannel):
         model_name: Any,
         model_preset: Any = None,
         context_window_tokens: Any = None,
+        is_fallback: Any = False,
     ) -> None:
         """Notify one chat's subscribers which model is handling its current request."""
         conns = list(self._subs.get(chat_id, ()))
@@ -2115,6 +2117,7 @@ class WebSocketChannel(BaseChannel):
             "event": "turn_model_updated",
             "chat_id": chat_id,
             "model_name": model_name.strip(),
+            "is_fallback": is_fallback is True,
         }
         if isinstance(model_preset, str) and model_preset.strip():
             body["model_preset"] = model_preset.strip()

nanobot/channels/websocket/tests/test_websocket_channel.py

@@ -2061,6 +2061,7 @@ async def test_send_scopes_turn_model_updates_to_the_subscribed_chat() -> None:
                 model="deepseek/deepseek-chat",
                 model_preset="Deep Research",
                 context_window_tokens=128_000,
+                is_fallback=True,
             ),
         )
     )
@@ -2072,6 +2073,7 @@ async def test_send_scopes_turn_model_updates_to_the_subscribed_chat() -> None:
         "model_name": "deepseek/deepseek-chat",
         "model_preset": "Deep Research",
         "context_window_tokens": 128_000,
+        "is_fallback": True,
     }
     chat_two.send.assert_not_awaited()
 

nanobot/session/webui_turns.py

@@ -495,6 +495,7 @@ def build_webui_fallback_model_observer(bus: MessageBus) -> FallbackModelObserve
                         if context.runtime is not None
                         else None
                     ),
+                    is_fallback=True,
                 ),
                 metadata=context.metadata,
             )

tests/utils/test_webui_turn_helpers.py

@@ -179,6 +179,7 @@ async def test_fallback_model_is_scoped_to_its_websocket_chat() -> None:
     assert isinstance(outbound.event, TurnModelUpdatedEvent)
     assert outbound.event.model == "deepseek/deepseek-chat"
     assert outbound.event.model_preset == "Deep Research"
+    assert outbound.event.is_fallback is True
 
 
 @pytest.mark.asyncio
@@ -218,6 +219,7 @@ async def test_admitted_runtime_publishes_chat_scoped_model_and_preset(tmp_path)
     assert isinstance(outbound.event, TurnModelUpdatedEvent)
     assert outbound.event.model == "openai-codex/gpt-5.6"
     assert outbound.event.model_preset == "Codex"
+    assert outbound.event.is_fallback is False
 
 
 @pytest.mark.asyncio

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,
       });
     });