fix(ui): restore delayed animation, handle tilde fences, fix follow-up scroll root cause

Author: waleedlatif1

apps/sim/app/workspace/[workspaceId]/home/components/mothership-chat/mothership-chat.tsx

@@ -176,7 +176,7 @@ export function MothershipChat({
                     blocks={msg.contentBlocks || []}
                     fallbackContent={msg.content}
                     isStreaming={isThisStreaming}
-                    onOptionSelect={isLastMessage && !isStreamActive ? onSubmit : undefined}
+                    onOptionSelect={isLastMessage ? onSubmit : undefined}
                     onWorkspaceResourceSelect={onWorkspaceResourceSelect}
                   />
                   {!isThisStreaming && (msg.content || msg.contentBlocks?.length) && (

apps/sim/hooks/use-auto-scroll.ts

@@ -117,12 +117,7 @@ export function useAutoScroll(
       el.removeEventListener('scroll', onScroll)
       observer.disconnect()
       cancelAnimationFrame(rafIdRef.current)
-      if (stickyRef.current) {
-        scrollToBottom()
-        const settled = new MutationObserver(() => scrollToBottom())
-        settled.observe(el, { childList: true, subtree: true })
-        setTimeout(() => settled.disconnect(), 300)
-      }
+      if (stickyRef.current) scrollToBottom()
     }
   }, [isStreaming, scrollToBottom])
 

apps/sim/hooks/use-streaming-reveal.ts

@@ -13,7 +13,10 @@ function findSafeSplitPoint(content: string): number {
   let i = 0
 
   while (i < content.length) {
-    if (content[i] === '`' && content[i + 1] === '`' && content[i + 2] === '`') {
+    const isBacktickFence = content[i] === '`' && content[i + 1] === '`' && content[i + 2] === '`'
+    const isTildeFence = content[i] === '~' && content[i + 1] === '~' && content[i + 2] === '~'
+
+    if (isBacktickFence || isTildeFence) {
       inCodeBlock = !inCodeBlock
       i += 3
       continue

apps/sim/tailwind.config.ts

@@ -223,6 +223,7 @@ export default {
         'placeholder-pulse': 'placeholder-pulse 1.5s ease-in-out infinite',
         'ring-pulse': 'ring-pulse 1.5s ease-in-out infinite',
         'stream-fade-in': 'stream-fade-in 300ms ease-out forwards',
+        'stream-fade-in-delayed': 'stream-fade-in 300ms ease-out 1.5s forwards',
         'thinking-block': 'thinking-block 1.6s ease-in-out infinite',
         'slide-in-right': 'slide-in-right 350ms ease-out forwards',
         'slide-in-bottom': 'slide-in-bottom 400ms cubic-bezier(0.16, 1, 0.3, 1)',