loop: the end of a subconvo is not an End of Turn

Co-Authored-By: sketch <hello@sketch.dev>
diff --git a/loop/agent.go b/loop/agent.go
index 315ff89..3076385 100644
--- a/loop/agent.go
+++ b/loop/agent.go
@@ -597,7 +597,7 @@
 	}
 
 	endOfTurn := false
-	if resp.StopReason != ant.StopReasonToolUse {
+	if resp.StopReason != ant.StopReasonToolUse && convo.Parent == nil {
 		endOfTurn = true
 	}
 	m := AgentMessage{