fix(ui): reduce markdown jank while responses stream (#19304)

packages/app/src/app.tsx

@@ -37,7 +37,6 @@ import { LayoutProvider } from "@/context/layout"
 import { ModelsProvider } from "@/context/models"
 import { NotificationProvider } from "@/context/notification"
 import { PermissionProvider } from "@/context/permission"
-import { usePlatform } from "@/context/platform"
 import { PromptProvider } from "@/context/prompt"
 import { ServerConnection, ServerProvider, serverName, useServer } from "@/context/server"
 import { SettingsProvider } from "@/context/settings"
@@ -77,11 +76,6 @@ declare global {
   }
 }
 
-function MarkedProviderWithNativeParser(props: ParentProps) {
-  const platform = usePlatform()
-  return <MarkedProvider nativeParser={platform.parseMarkdown}>{props.children}</MarkedProvider>
-}
-
 function QueryProvider(props: ParentProps) {
   const client = new QueryClient()
   return <QueryClientProvider client={client}>{props.children}</QueryClientProvider>
@@ -144,9 +138,9 @@ export function AppBaseProviders(props: ParentProps<{ locale?: Locale }>) {
             <ErrorBoundary fallback={(error) => <ErrorPage error={error} />}>
               <QueryProvider>
                 <DialogProvider>
-                  <MarkedProviderWithNativeParser>
+                  <MarkedProvider>
                     <FileComponentProvider component={File}>{props.children}</FileComponentProvider>
-                  </MarkedProviderWithNativeParser>
+                  </MarkedProvider>
                 </DialogProvider>
               </QueryProvider>
             </ErrorBoundary>

packages/app/src/pages/session/message-timeline.tsx

@@ -943,7 +943,10 @@ export function MessageTimeline(props: {
                         "min-w-0 w-full max-w-full": true,
                         "md:max-w-200 2xl:max-w-[1000px]": props.centered,
                       }}
-                      style={{ "content-visibility": "auto", "contain-intrinsic-size": "auto 500px" }}
+                      style={{
+                        "content-visibility": active() ? undefined : "auto",
+                        "contain-intrinsic-size": active() ? undefined : "auto 500px",
+                      }}
                     >
                       <Show when={commentCount() > 0}>
                         <div class="w-full px-4 md:px-5 pb-2">