fix(client): address remaining conversation review feedback

packages/client/ui-conversation/src/client/chat/TurnTailNodeView.tsx

@@ -9,9 +9,11 @@ type TurnTailNodeViewProps = ChatNodeViewProps<'turn-tail'> & PropsRenderSlots<'
 
 /** Turn-local actions and feature tail over the Location index, independent of Assistant placement. */
 export const TurnTailNodeView = memo(function TurnTailNodeView({
-  node, openFile, forkAt, renderSlotChain, t,
+  node, openFile, forkAt, renderSlotChain, t, useSession,
 }: TurnTailNodeViewProps) {
   const data = node.data
+  const hasLaterChatNode = useSession(snapshot =>
+    snapshot.chat.locations.getTurn(data.turn).at(-1) !== node.key)
   const turn = node.location.kind === 'turn' || node.location.kind === 'step'
     ? node.location.turn
     : undefined
@@ -34,7 +36,7 @@ export const TurnTailNodeView = memo(function TurnTailNodeView({
         tokensPerSecond={data.tokensPerSecond}
         clock="end"
         onBranch={() => { forkAt(closing.finalNode.seq) }}
-        branchUnavailable={data.branchUnavailable}
+        branchUnavailable={data.branchUnavailable || hasLaterChatNode}
         className={css.actions}
         t={t}
       />

packages/client/ui-conversation/src/client/contract/chat-nodes.ts

@@ -57,7 +57,7 @@ export interface TurnTailChatData {
   readonly time: number
   /** Last finalized content-bearing Assistant in this Turn. */
   readonly closing: FinalAssistantChatData | null
-  /** Whether later Assistant/Step material makes the closing seq non-tail. */
+  /** Whether non-rendered later evidence makes the closing seq non-tail. */
   readonly branchUnavailable: boolean
   readonly ttftMs?: number
   readonly tokensPerSecond?: number