fix(chat): separate copied message segments

Author: j15z

apps/sim/app/workspace/[workspaceId]/home/components/message-content/message-content.test.ts

@@ -120,7 +120,7 @@ describe('getRenderableMessageText', () => {
       mainText('Main answer.'),
     ]
 
-    expect(getRenderableMessageText(blocks, 'Fallback.')).toBe('Visible research. Main answer.')
+    expect(getRenderableMessageText(blocks, 'Fallback.')).toBe('Visible research. \n\nMain answer.')
   })
 
   it('omits legacy subagent text that has no parent group', () => {
@@ -141,7 +141,22 @@ describe('getRenderableMessageText', () => {
       mainText('Main answer.'),
     ]
 
-    expect(getRenderableMessageText(blocks, 'Fallback.')).toBe('Visible research. Main answer.')
+    expect(getRenderableMessageText(blocks, 'Fallback.')).toBe('Visible research. \n\nMain answer.')
+  })
+
+  it('separates rendered blocks when streamed text has no boundary whitespace', () => {
+    const blocks: ContentBlock[] = [
+      subagentStart('research', 'span-visible', 'main'),
+      {
+        type: 'subagent_text',
+        content: 'Visible research.',
+        spanId: 'span-visible',
+        timestamp: 2,
+      },
+      mainText('Main answer.'),
+    ]
+
+    expect(getRenderableMessageText(blocks, 'Fallback.')).toBe('Visible research.\n\nMain answer.')
   })
 })
 

apps/sim/app/workspace/[workspaceId]/home/components/message-content/message-content.tsx

@@ -492,28 +492,32 @@ export function parseBlocks(blocks: ContentBlock[]): MessageSegment[] {
   return parseBlocksLegacy(blocks)
 }
 
+function joinRenderableText(parts: string[]): string {
+  return parts.filter(Boolean).join('\n\n')
+}
+
 function getAgentGroupText(items: AgentGroupItem[]): string {
-  return items
-    .map((item) => {
+  return joinRenderableText(
+    items.map((item) => {
       if (item.type === 'text') return item.content
       if (item.type === 'agent_group') return getAgentGroupText(item.group.items)
       return ''
     })
-    .join('')
+  )
 }
 
 /** Returns only the text represented by the same segment tree the transcript renders. */
 export function getRenderableMessageText(blocks: ContentBlock[], fallbackContent: string): string {
   const parsed = blocks.length > 0 ? parseBlocks(blocks) : []
   if (parsed.length === 0) return fallbackContent
 
-  return parsed
-    .map((segment) => {
+  return joinRenderableText(
+    parsed.map((segment) => {
       if (segment.type === 'text') return segment.content
       if (segment.type === 'agent_group') return getAgentGroupText(segment.items)
       return ''
     })
-    .join('')
+  )
 }
 
 function parseBlocksLegacy(blocks: ContentBlock[]): MessageSegment[] {