feat(desktop): render session usage footer at transcript end

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/desktop/src/app/chat/index.tsx

@@ -70,9 +70,9 @@ import { ProfileTag } from './profile-tag'
 import { isRouteSessionMismatch } from './route-session-state'
 import { useRuntimeMessageRepository } from './runtime-repository'
 import { ScrollToBottomButton } from './scroll-to-bottom-button'
+import { SessionUsageFooter } from './session-usage-footer'
 import { useSessionView } from './session-view'
 import { SessionActionsMenu } from './sidebar/session-actions-menu'
-import { WorkspaceBar } from './workspace-bar'
 import { routedSessionIsLoading, threadLoadingState } from './thread-loading'
 import {
   backfillOlderTranscriptPage,
@@ -80,6 +80,7 @@ import {
   transcriptBackfillAvailable
 } from './transcript-backfill'
 import { advanceSessionTranscriptWindow, type SessionWindowMemo } from './transcript-window'
+import { WorkspaceBar } from './workspace-bar'
 
 interface ChatViewProps extends Omit<React.ComponentProps<'div'>, 'onSubmit'> {
   gateway: HermesGateway | null
@@ -692,6 +693,15 @@ const ChatViewContent = memo(function ChatViewContent({
 
   const overlayKind: DragKind = dragKind === 'files' ? 'files' : sessionDragging && !sessionEdgeHover ? 'session' : null
 
+  // Identity must be stable across ChatView re-renders: this is a prop of the
+  // memo'd Thread/ThreadMessageList, and a fresh element per render would
+  // defeat their bail-out. Stats changes re-render inside SessionUsageFooter
+  // via its own useStore($sessions) subscription, not through these props.
+  const threadFooter = useMemo(
+    () => (activeSessionId ? <SessionUsageFooter sessionId={activeSessionId} /> : undefined),
+    [activeSessionId]
+  )
+
   return (
     <div
       className={cn(
@@ -739,6 +749,7 @@ const ChatViewContent = memo(function ChatViewContent({
           <Thread
             clampToComposer={showChatBar}
             cwd={currentCwd}
+            footer={threadFooter}
             gateway={gateway}
             intro={showIntro ? { personality: introPersonality, seed: introSeed } : undefined}
             loading={threadLoading}

apps/desktop/src/components/assistant-ui/thread/index.tsx

@@ -1,4 +1,4 @@
-import { createContext, memo, useCallback, useContext, useMemo, useRef, useState } from 'react'
+import { createContext, memo, type ReactNode, useCallback, useContext, useMemo, useRef, useState } from 'react'
 
 import { ChatEmptySlot } from '@/components/assistant-ui/chat-empty-slot'
 import { AssistantMessage } from '@/components/assistant-ui/thread/assistant-message'
@@ -36,6 +36,7 @@ const ThreadEditContext = createContext<ThreadEditContextValue>({ cwd: null, gat
 interface ThreadProps {
   clampToComposer?: boolean
   cwd?: string | null
+  footer?: ReactNode
   gateway?: HermesGateway | null
   intro?: IntroProps
   loading?: ThreadLoadingState
@@ -58,6 +59,7 @@ interface ThreadProps {
 export const Thread = memo(function Thread({
   clampToComposer = false,
   cwd = null,
+  footer,
   gateway = null,
   intro,
   loading,
@@ -176,6 +178,7 @@ export const Thread = memo(function Thread({
           clampToComposer={clampToComposer}
           components={messageComponents}
           emptyPlaceholder={emptyPlaceholder}
+          footer={footer}
           loadingIndicator={loadingIndicator}
           scrollProfile={scrollProfile}
           sessionId={sessionId}

apps/desktop/src/components/assistant-ui/thread/list.tsx

@@ -231,6 +231,7 @@ interface ThreadMessageListProps {
   clampToComposer: boolean
   components: ThreadMessageComponents
   emptyPlaceholder?: ReactNode
+  footer?: ReactNode
   loadingIndicator?: ReactNode
   sessionId?: string | null
   sessionKey?: string | null
@@ -421,6 +422,7 @@ const ThreadMessageListInner: FC<ThreadMessageListProps> = ({
   clampToComposer,
   components,
   emptyPlaceholder,
+  footer,
   loadingIndicator,
   sessionId = null,
   scrollProfile,
@@ -1064,6 +1066,7 @@ const ThreadMessageListInner: FC<ThreadMessageListProps> = ({
       if (contentRef.current) {
         resizeObserver.observe(contentRef.current)
       }
+
       void scrollToBottom('instant')
     }
 
@@ -1365,6 +1368,7 @@ const ThreadMessageListInner: FC<ThreadMessageListProps> = ({
             )}
             {rows}
             {loadingIndicator}
+            {footer}
             {clampToComposer && (
               <div
                 aria-hidden="true"