fix: use selected model in webchat side threads (#10065)

dashboard/src/components/chat/Chat.vue

@@ -467,6 +467,7 @@
       :thread="activeThread"
       :is-dark="isDark"
       :deleting="deletingThread"
+      :get-provider-selection="getSelectedProviderSelection"
       @delete="deleteThread"
     />
     <ReasoningSidebar

dashboard/src/components/chat/ThreadPanel.vue

@@ -83,6 +83,7 @@ const props = defineProps<{
   thread: ChatThread | null;
   isDark: boolean;
   deleting?: boolean;
+  getProviderSelection: () => { providerId: string; modelName: string };
 }>();
 
 const emit = defineEmits<{
@@ -155,6 +156,7 @@ async function send() {
   const abort = new AbortController();
   sending.value = true;
   try {
+    const selection = props.getProviderSelection();
     const response = await fetchWithAuth(
       chatApi.sendThreadMessageUrl(props.thread.thread_id),
       {
@@ -165,6 +167,8 @@ async function send() {
         body: JSON.stringify({
           message: [{ type: "plain", text }],
           flags: buildChatRequestFlags(),
+          selected_provider: selection.providerId,
+          selected_model: selection.modelName,
         }),
         signal: abort.signal,
       },