ui : drop unused currentResponse reactive writes

Nothing reads chatStore.currentResponse, but setChatStreaming reassigned
it on every streamed chunk, so each token paid a reactive write and string
assignment for nothing. Remove the field and the clearUIState wrapper
that only reset it.

Assisted-by: pi:zai-org/GLM-5.3

tools/ui/src/lib/stores/chat/index.svelte.ts

@@ -55,7 +55,6 @@ class ChatStore implements ChatStreamHost, ChatFlowsHost {
 		string,
 		{ response: string; messageId: string; model?: string | null }
 	>();
-	currentResponse = $state('');
 	errorDialogState = $state<ErrorDialogState | null>(null);
 	// true while the active conversation has a local pipe (send, attach or resume-wait)
 	isLoading = $derived(this.activity.isLocal(conversationsStore.activeConversation?.id ?? ''));
@@ -256,8 +255,6 @@ class ChatStore implements ChatStreamHost, ChatFlowsHost {
 		}
 
 		this.chatStreamingStates.delete(convId);
-
-		if (convId === conversationsStore.activeConversation?.id) this.currentResponse = '';
 	}
 	clearEditMode(): void {
 		this.isEditModeActive = false;
@@ -272,11 +269,6 @@ class ChatStore implements ChatStreamHost, ChatFlowsHost {
 		this.pendingMessages.delete(convId);
 	}
 
-	/** Reset per-view state when (re)mounting the empty chat screen. */
-	clearUIState(): void {
-		this.currentResponse = '';
-	}
-
 	consumePendingDraft(): { message: string; files: ChatUploadedFile[] } | null {
 		if (!this.pendingDraftMessage && this.pendingDraftFiles.length === 0) return null;
 
@@ -766,8 +758,6 @@ class ChatStore implements ChatStreamHost, ChatFlowsHost {
 			model: model ?? this.chatStreamingStates.get(convId)?.model,
 			response
 		});
-
-		if (convId === conversationsStore.activeConversation?.id) this.currentResponse = response;
 	}
 
 	setEditModeActive(handler: (files: File[]) => void): void {
@@ -1244,7 +1234,6 @@ class ChatStore implements ChatStreamHost, ChatFlowsHost {
 	syncLoadingStateForChat(convId: string): void {
 		const s = this.chatStreamingStates.get(convId);
 
-		this.currentResponse = s?.response || '';
 		this.processing.setActiveConversation(convId);
 
 		// Sync streaming content to activeMessages so UI displays current content

tools/ui/src/routes/(chat)/+page.svelte

@@ -3,7 +3,7 @@
 	import { page } from '$app/state';
 	import { DialogModelNotAvailable } from '$lib/components/app';
 	import { APP_NAME, URL_PARAMS } from '$lib/constants';
-	import { chatStore, conversationsStore, modelsStore, serverStore } from '$lib/stores';
+	import { conversationsStore, modelsStore, serverStore } from '$lib/stores';
 	import { onMount } from 'svelte';
 
 	let qParam = $derived(page.url.searchParams.get(URL_PARAMS.QUERY));
@@ -77,7 +77,6 @@
 		}
 
 		conversationsStore.clearActiveConversation();
-		chatStore.clearUIState();
 
 		await modelsStore.fetch();