diff --git a/desktop/src/features/channels/ui/ChannelScreen.tsx b/desktop/src/features/channels/ui/ChannelScreen.tsx
index fc31dace7..8d313fa54 100644
--- a/desktop/src/features/channels/ui/ChannelScreen.tsx
+++ b/desktop/src/features/channels/ui/ChannelScreen.tsx
@@ -397,11 +397,9 @@ export function ChannelScreen({
       if (!parentEventId) {
         return;
       }
-      const agentReplyParentId = currentThreadHeadId ?? null;
       const branchHeadId = currentThreadHeadId ?? null;
 
       await sendMessageMutation.mutateAsync({
-        agentReplyParentId,
         branchHeadId,
         content,
         mentionPubkeys,
diff --git a/desktop/src/features/messages/lib/threadBranch.ts b/desktop/src/features/messages/lib/threadBranch.ts
index 68fbb3aee..8a98db53e 100644
--- a/desktop/src/features/messages/lib/threadBranch.ts
+++ b/desktop/src/features/messages/lib/threadBranch.ts
@@ -74,7 +74,12 @@ export function collectThreadBranch(
     )
     .map((message) => ({
       ...message,
-      depth: Math.max(0, message.depth - depthOffset),
+      // Keep normal replies in the drilled branch visually flat.
+      // Only explicitly drilled nested branches get their own branchHeadId and collapse link.
+      depth:
+        message.branchHeadId === branchHeadId
+          ? 0
+          : Math.max(0, message.depth - depthOffset),
     }));
 
   return {