fix(webui): broadcast runtime model updates

Co-authored-by: Cursor <cursoragent@cursor.com>

webui/src/lib/nanobot-client.ts

@@ -14,6 +14,7 @@ const WS_CLOSING = 2;
 type Unsubscribe = () => void;
 type EventHandler = (ev: InboundEvent) => void;
 type StatusHandler = (status: ConnectionStatus) => void;
+type RuntimeModelHandler = (modelName: string | null, modelPreset?: string | null) => void;
 
 /** Structured connection-level errors surfaced to the UI.
  *
@@ -58,6 +59,7 @@ export interface NanobotClientOptions {
 export class NanobotClient {
   private socket: WebSocket | null = null;
   private statusHandlers = new Set<StatusHandler>();
+  private runtimeModelHandlers = new Set<RuntimeModelHandler>();
   private errorHandlers = new Set<ErrorHandler>();
   // chat_id -> handlers listening on it
   private chatHandlers = new Map<string, Set<EventHandler>>();
@@ -107,6 +109,13 @@ export class NanobotClient {
     };
   }
 
+  onRuntimeModelUpdate(handler: RuntimeModelHandler): Unsubscribe {
+    this.runtimeModelHandlers.add(handler);
+    return () => {
+      this.runtimeModelHandlers.delete(handler);
+    };
+  }
+
   /** Subscribe to transport-level faults (see :type:`StreamError`). */
   onError(handler: ErrorHandler): Unsubscribe {
     this.errorHandlers.add(handler);
@@ -245,10 +254,21 @@ export class NanobotClient {
       return;
     }
 
+    if (parsed.event === "runtime_model_updated") {
+      this.emitRuntimeModelUpdate(parsed.model_name || null, parsed.model_preset ?? null);
+      return;
+    }
+
     const chatId = (parsed as { chat_id?: string }).chat_id;
     if (chatId) this.dispatch(chatId, parsed);
   }
 
+  private emitRuntimeModelUpdate(modelName: string | null, modelPreset?: string | null): void {
+    for (const handler of this.runtimeModelHandlers) {
+      handler(modelName, modelPreset);
+    }
+  }
+
   private dispatch(chatId: string, ev: InboundEvent): void {
     const handlers = this.chatHandlers.get(chatId);
     if (!handlers) return;

webui/src/lib/types.ts

@@ -147,8 +147,6 @@ export type InboundEvent =
       /** Present when the frame is an agent breadcrumb (e.g. tool hint,
        * generic progress line) rather than a conversational reply. */
       kind?: "tool_hint" | "progress";
-      /** Runtime model name after commands like `/model fast` update it. */
-      model_name?: string | null;
     }
   | {
       event: "delta";
@@ -161,6 +159,11 @@ export type InboundEvent =
       chat_id: string;
       stream_id?: string;
     }
+  | {
+      event: "runtime_model_updated";
+      model_name: string;
+      model_preset?: string | null;
+    }
   | { event: "turn_end"; chat_id: string }
   | { event: "session_updated"; chat_id: string }
   | { event: "error"; chat_id?: string; detail?: string };