ui : follow the svelte runes guidance in chat message code

Two effects detected changes with manual previous-value refs and reset
flags. The permission request carries object identity, so its dismissal
is now a derived comparing the dismissed request; the continue request
is a bare boolean, so its dismissal only shrinks to a reset while no
request is pending. Also drop a dead if (browser) guard in the markdown
theme loader - effects never run on the server.

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

tools/ui/src/lib/components/app/chat/ChatMessages/ChatMessageAgenticContent.svelte

@@ -46,49 +46,44 @@
 		isLastAssistantMessage ? !!agenticStore.getLastError(message.convId) : false
 	);
 
-	let permissionDismissed = $state(false);
-
 	const pendingPermission = $derived(
 		isStreaming && isLastAssistantMessage
 			? agenticStore.getPendingPermissionRequest(message.convId)
 			: null
 	);
 
-	let prevPendingRef: typeof pendingPermission = null;
-	$effect(() => {
-		if (pendingPermission !== prevPendingRef) {
-			prevPendingRef = pendingPermission;
+	// dismissal applies to the request object, so the next request ( new
+	// identity ) shows the card again without any reset bookkeeping
+	let dismissedPermission: typeof pendingPermission = $state(null);
 
-			if (pendingPermission) {
-				permissionDismissed = false;
-			}
-		}
-	});
+	const visiblePermission = $derived(
+		pendingPermission && dismissedPermission !== pendingPermission ? pendingPermission : null
+	);
 
 	function handlePermission(decision: ToolPermissionDecision) {
-		permissionDismissed = true;
+		dismissedPermission = pendingPermission;
 		agenticStore.resolvePermission(message.convId, decision);
 	}
 
-	let continueDismissed = $state(false);
-
 	const pendingContinue = $derived(
 		isStreaming && isLastAssistantMessage
 			? agenticStore.getPendingContinueRequest(message.convId)
 			: false
 	);
 
-	let prevContinueRef = false;
-	$effect(() => {
-		if (pendingContinue !== prevContinueRef) {
-			prevContinueRef = pendingContinue;
+	let continueDismissed = $state(false);
 
-			if (pendingContinue) {
-				continueDismissed = false;
-			}
+	// the continue request is a plain boolean, so there is no identity to
+	// compare against; clear the dismissal whenever no request is pending so
+	// the next one starts from a clean state
+	$effect(() => {
+		if (!pendingContinue) {
+			continueDismissed = false;
 		}
 	});
 
+	const showContinue = $derived(Boolean(pendingContinue) && !continueDismissed);
+
 	function handleContinue(shouldContinue: boolean) {
 		continueDismissed = true;
 		agenticStore.resolveContinue(message.convId, shouldContinue);
@@ -238,15 +233,15 @@
 		{/each}
 	{/if}
 
-	{#if pendingPermission && !permissionDismissed}
+	{#if visiblePermission}
 		<ChatMessageActionCardPermissionRequest
 			onDecision={handlePermission}
-			serverLabel={pendingPermission.serverLabel}
-			toolName={pendingPermission.toolName}
+			serverLabel={visiblePermission.serverLabel}
+			toolName={visiblePermission.toolName}
 		/>
 	{/if}
 
-	{#if pendingContinue && !continueDismissed}
+	{#if showContinue}
 		<ChatMessageActionCardContinueRequest onDecision={handleContinue} />
 	{/if}
 </div>

tools/ui/src/lib/components/app/content/MarkdownContent/MarkdownContent.svelte

@@ -7,7 +7,6 @@
 		getMdastNodeHash,
 		isAppendMode
 	} from './markdown-utils';
-	import { browser } from '$app/environment';
 	import {
 		ActionIconCopyToClipboard,
 		CodeBlockActions,
@@ -153,8 +152,6 @@
 	 * @param isDark - Whether to load the dark theme (true) or light theme (false)
 	 */
 	function loadHighlightTheme(isDark: boolean) {
-		if (!browser) return;
-
 		document
 			.querySelectorAll(`style[${UI_DATA_ATTRS.HIGHLIGHT_THEME_PREVIEW}]`)
 			.forEach((style) => style.remove());