diff --git a/backend/api/server.py b/backend/api/server.py
index 3cfdd80..16e5103 100644
--- a/backend/api/server.py
+++ b/backend/api/server.py
@@ -3799,34 +3799,68 @@ def _annotate_last_assistant_elapsed(
     session_id: str,
     elapsed_ms: int,
 ) -> None:
-    path = _session_json_path(directory, session_id)
     try:
-        data = json.loads(path.read_text(encoding='utf-8'))
-    except (OSError, json.JSONDecodeError):
+        stored = load_agent_session(session_id, directory=directory)
+    except (
+        FileNotFoundError,
+        OSError,
+        json.JSONDecodeError,
+        KeyError,
+        TypeError,
+        ValueError,
+    ):
         return
-    messages = data.get('messages')
-    display_messages = data.get('display_messages')
-    if not isinstance(display_messages, list):
-        display_messages = messages
-    if not isinstance(messages, list) and not isinstance(display_messages, list):
+
+    messages, messages_changed = _annotate_last_assistant_in_messages(
+        stored.messages,
+        elapsed_ms,
+    )
+    display_messages: tuple[dict[str, Any], ...] = ()
+    display_changed = False
+    if stored.display_messages:
+        display_messages, display_changed = _annotate_last_assistant_in_messages(
+            stored.display_messages,
+            elapsed_ms,
+        )
+
+    if not messages_changed and not display_changed:
         return
-    for message_list in (messages, display_messages):
-        if not isinstance(message_list, list):
+
+    save_agent_session(
+        replace(
+            stored,
+            messages=messages if messages_changed else stored.messages,
+            display_messages=(
+                display_messages
+                if display_changed
+                else stored.display_messages
+            ),
+        ),
+        directory=directory,
+    )
+
+
+def _annotate_last_assistant_in_messages(
+    messages: tuple[dict[str, Any], ...] | tuple[Any, ...],
+    elapsed_ms: int,
+) -> tuple[tuple[dict[str, Any], ...], bool]:
+    updated = [dict(message) for message in messages if isinstance(message, dict)]
+    for index in range(len(updated) - 1, -1, -1):
+        message = updated[index]
+        if message.get('role') != 'assistant':
             continue
-        for message in reversed(message_list):
-            if not isinstance(message, dict) or message.get('role') != 'assistant':
-                continue
-            metadata = message.get('metadata')
-            if not isinstance(metadata, dict):
-                metadata = {}
-                message['metadata'] = metadata
-            metadata['elapsed_ms'] = elapsed_ms
-            break
-    try:
-        path.write_text(json.dumps(data, ensure_ascii=False, indent=2), encoding='utf-8')
-    except OSError:
-        return
-    return
+        metadata = message.get('metadata')
+        if not isinstance(metadata, dict):
+            metadata = {}
+        else:
+            metadata = dict(metadata)
+        if metadata.get('elapsed_ms') == elapsed_ms:
+            return tuple(updated), False
+        metadata['elapsed_ms'] = elapsed_ms
+        message['metadata'] = metadata
+        updated[index] = message
+        return tuple(updated), True
+    return tuple(updated), False
 
 
 def _read_session_title(directory: Path, session_id: str | None) -> str | None:
diff --git a/frontend/app/components/assistant-ui/threadlist-sidebar.tsx b/frontend/app/components/assistant-ui/threadlist-sidebar.tsx
index 3e3cf7c..3e49337 100644
--- a/frontend/app/components/assistant-ui/threadlist-sidebar.tsx
+++ b/frontend/app/components/assistant-ui/threadlist-sidebar.tsx
@@ -148,7 +148,7 @@ export function ThreadListSidebar({
 						<SidebarMenu>
 							<SidebarMenuItem>
 								<SidebarMenuButton size="lg">
-									<div className="aui-sidebar-header-icon-wrapper flex aspect-square size-8 items-center justify-center rounded-lg bg-sidebar-primary text-sidebar-primary-foreground">
+									<div className="aui-sidebar-header-icon-wrapper flex aspect-square size-8 items-center justify-center rounded-lg bg-sidebar-accent text-sidebar-foreground">
 										<BotIcon className="aui-sidebar-header-icon size-4" />
 									</div>
 									<div className="aui-sidebar-header-heading mr-6 flex flex-col gap-0.5 leading-none">
@@ -647,7 +647,7 @@ function AccountMenu({
 				{compact ? (
 					<button
 						type="button"
-						className="flex size-8 items-center justify-center rounded-full bg-sidebar-primary text-sidebar-primary-foreground transition-colors hover:bg-sidebar-accent hover:text-sidebar-accent-foreground"
+						className="flex size-8 items-center justify-center rounded-full bg-sidebar-accent text-sidebar-foreground transition-colors hover:bg-sidebar-accent/80 hover:text-sidebar-accent-foreground"
 						aria-label="账号与统计"
 						title={account.username}
 					>
@@ -660,7 +660,7 @@ function AccountMenu({
 						type="button"
 						className="flex w-full items-center gap-2 rounded-lg px-2 py-2 text-left transition-colors hover:bg-sidebar-accent"
 					>
-						<div className="flex size-8 shrink-0 items-center justify-center rounded-lg bg-sidebar-primary text-sidebar-primary-foreground">
+						<div className="flex size-8 shrink-0 items-center justify-center rounded-lg bg-sidebar-accent text-sidebar-foreground">
 							<UserIcon className="size-4" />
 						</div>
 						<div className="min-w-0 flex-1">