address comments

Author: icecrasher321

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

@@ -199,6 +199,7 @@ function parseBlocks(blocks: ContentBlock[]): MessageSegment[] {
       for (const [key, g] of groupsByKey) {
         if (key.endsWith(`:${parentToolCallId}`)) return g
       }
+      return undefined
     }
     if (activeGroupKey) return groupsByKey.get(activeGroupKey)
     return undefined

apps/sim/lib/copilot/request/go/stream.ts

@@ -380,6 +380,15 @@ export async function runStreamLoop(
                   timestamp: Date.now(),
                 })
               }
+            } else {
+              // Protocol invariant: every subagent_start carries scope.parentToolCallId
+              // (or data.tool_call_id) and a subagent name. If we see otherwise the
+              // group cannot be keyed and the lane will not render — log so a
+              // server-side regression is visible.
+              logger.warn('subagent start missing toolCallId or agent name', {
+                hasToolCallId: Boolean(toolCallId),
+                hasSubagentName: Boolean(subagentName),
+              })
             }
             return
           }