Merge commit 'df52bea0d0cb5889f9c5e324c54f2bdce9e30378'

.gitignore

@@ -38,6 +38,7 @@ desktop/brand-assets/
 
 # Superpowers plans & specs (local only)
 docs/superpowers/
+.superpowers/
 
 # Temp server/web logs
 .tmp-*.log
@@ -64,4 +65,4 @@ docs/.vitepress/cache
 runtime/__pycache__
 
 # IDE
-.idea
+.idea

desktop/scripts/e2e-rewind-agent-browser.sh

@@ -137,10 +137,10 @@ fi
 
 ${AB} screenshot "${ARTIFACT_DIR}/03-after-edit.png" >/dev/null
 
-${AB} eval "const button = [...document.querySelectorAll('button')].find((node) => node.getAttribute('aria-label') === 'Rewind to here'); if (!button) throw new Error('Rewind button not found'); button.click();"
+${AB} find role button click --name "Undo current turn changes"
 ${AB} wait 1500
-${AB} screenshot "${ARTIFACT_DIR}/04-rewind-modal.png" >/dev/null
-${AB} find role button click --name "Rewind here"
+${AB} screenshot "${ARTIFACT_DIR}/04-undo-current-turn-confirm.png" >/dev/null
+${AB} find role button click --name "Undo current turn"
 
 for _ in $(seq 1 120); do
   if grep -q "before-rewind" "${TARGET_FILE}" && ! grep -q "after-rewind" "${TARGET_FILE}"; then

desktop/scripts/e2e-rewind-complex-agent-browser.sh

@@ -171,10 +171,10 @@ wait_for_file_contains "${README_FILE}" "Second turn touched README" 60
 wait_for_file_contains "${GENERATED_FILE}" "second-turn" 60
 ${AB} screenshot "${ARTIFACT_DIR}/04-after-second-turn.png" >/dev/null
 
-${AB} eval "const buttons = [...document.querySelectorAll('button')].filter((node) => node.getAttribute('aria-label') === 'Rewind to here'); if (buttons.length < 2) throw new Error('Expected at least two Rewind buttons, found ' + buttons.length); buttons[buttons.length - 1].click();"
+${AB} find role button click --name "Undo current turn changes"
 ${AB} wait 1500
-${AB} screenshot "${ARTIFACT_DIR}/05-rewind-second-turn-modal.png" >/dev/null
-${AB} find role button click --name "Rewind here"
+${AB} screenshot "${ARTIFACT_DIR}/05-undo-second-turn-confirm.png" >/dev/null
+${AB} find role button click --name "Undo current turn"
 
 for _ in $(seq 1 120); do
   if grep -q "turn-one" "${APP_FILE}" \

desktop/src/__tests__/pages.test.tsx

@@ -1,4 +1,4 @@
-import { describe, it, expect, vi } from 'vitest'
+import { beforeEach, describe, it, expect, vi } from 'vitest'
 import { fireEvent, render, screen } from '@testing-library/react'
 import '@testing-library/jest-dom'
 
@@ -46,9 +46,14 @@ import { ToolInspection } from '../pages/ToolInspection'
 import { Sidebar } from '../components/layout/Sidebar'
 import { UserMessage } from '../components/chat/UserMessage'
 import { useChatStore } from '../stores/chatStore'
+import { useSettingsStore } from '../stores/settingsStore'
 import { useSessionStore } from '../stores/sessionStore'
 import { useTabStore } from '../stores/tabStore'
 
+beforeEach(() => {
+  useSettingsStore.setState({ locale: 'en' })
+})
+
 /**
  * Core rendering tests: content-only pages must render without crashing
  * and contain key structural elements from the prototype.
@@ -576,7 +581,8 @@ describe('Design system compliance', () => {
         html.includes('C47A5A') ||
         html.includes('8F482F') ||
         html.includes('var(--color-brand)') ||
-        html.includes('bg-[var(--color-brand)]'),
+        html.includes('bg-[var(--color-brand)]') ||
+        html.includes('var(--gradient-btn-primary)'),
       ).toBe(true)
       unmount()
     }

desktop/src/api/sessions.ts

@@ -139,6 +139,82 @@ export type SessionInspectionResponse = {
   errors?: Record<string, string>
 }
 
+export type WorkspaceFileStatus =
+  | 'modified'
+  | 'added'
+  | 'deleted'
+  | 'renamed'
+  | 'untracked'
+  | 'copied'
+  | 'type_changed'
+  | 'unknown'
+
+export type WorkspaceChangedFile = {
+  path: string
+  oldPath?: string
+  status: WorkspaceFileStatus
+  additions: number
+  deletions: number
+}
+
+export type WorkspaceStatusResult = {
+  state: 'ok' | 'not_git_repo' | 'missing_workdir' | 'error'
+  workDir: string
+  repoName: string | null
+  branch: string | null
+  isGitRepo: boolean
+  changedFiles: WorkspaceChangedFile[]
+  error?: string
+}
+
+export type WorkspaceReadFileResult = {
+  state: 'ok' | 'binary' | 'too_large' | 'missing' | 'error'
+  path: string
+  previewType?: 'text' | 'image'
+  content?: string
+  dataUrl?: string
+  mimeType?: string
+  language: string
+  size: number
+  truncated?: boolean
+  readBytes?: number
+  error?: string
+}
+
+export type WorkspaceTreeEntry = {
+  name: string
+  path: string
+  isDirectory: boolean
+}
+
+export type WorkspaceTreeResult = {
+  state: 'ok' | 'missing' | 'error'
+  path: string
+  entries: WorkspaceTreeEntry[]
+  error?: string
+}
+
+export type WorkspaceDiffResult = {
+  state: 'ok' | 'missing' | 'not_git_repo' | 'error'
+  path: string
+  diff?: string
+  error?: string
+}
+
+function buildWorkspacePath(
+  sessionId: string,
+  resource: 'status' | 'tree' | 'file' | 'diff',
+  workspacePath?: string,
+) {
+  const query = new URLSearchParams()
+  if (typeof workspacePath === 'string' && workspacePath.length > 0) {
+    query.set('path', workspacePath)
+  }
+
+  const qs = query.toString()
+  return `/api/sessions/${sessionId}/workspace/${resource}${qs ? `?${qs}` : ''}`
+}
+
 export const sessionsApi = {
   list(params?: { project?: string; limit?: number; offset?: number }) {
     const query = new URLSearchParams()
@@ -187,6 +263,22 @@ export const sessionsApi = {
     })
   },
 
+  getWorkspaceStatus(sessionId: string) {
+    return api.get<WorkspaceStatusResult>(buildWorkspacePath(sessionId, 'status'))
+  },
+
+  getWorkspaceTree(sessionId: string, workspacePath = '') {
+    return api.get<WorkspaceTreeResult>(buildWorkspacePath(sessionId, 'tree', workspacePath))
+  },
+
+  getWorkspaceFile(sessionId: string, workspacePath: string) {
+    return api.get<WorkspaceReadFileResult>(buildWorkspacePath(sessionId, 'file', workspacePath))
+  },
+
+  getWorkspaceDiff(sessionId: string, workspacePath: string) {
+    return api.get<WorkspaceDiffResult>(buildWorkspacePath(sessionId, 'diff', workspacePath))
+  },
+
   rewind(sessionId: string, body: {
     targetUserMessageId?: string
     userMessageIndex?: number

desktop/src/components/chat/AskUserQuestion.test.tsx

@@ -24,6 +24,7 @@ vi.mock('../../api/sessions', () => ({
 
 import { AskUserQuestion } from './AskUserQuestion'
 import { useChatStore } from '../../stores/chatStore'
+import { useSettingsStore } from '../../stores/settingsStore'
 import { useTabStore } from '../../stores/tabStore'
 
 const ACTIVE_TAB = 'active-tab'
@@ -31,6 +32,7 @@ const ACTIVE_TAB = 'active-tab'
 describe('AskUserQuestion', () => {
   beforeEach(() => {
     sendMock.mockReset()
+    useSettingsStore.setState({ locale: 'en' })
     useTabStore.setState({
       activeTabId: ACTIVE_TAB,
       tabs: [{ sessionId: ACTIVE_TAB, title: 'Test', type: 'session', status: 'idle' }],

desktop/src/components/chat/AttachmentGallery.tsx

@@ -5,8 +5,13 @@ export type AttachmentPreview = {
   id?: string
   type: 'image' | 'file'
   name: string
+  path?: string
   data?: string
   previewUrl?: string
+  lineStart?: number
+  lineEnd?: number
+  note?: string
+  quote?: string
 }
 
 type Props = {
@@ -35,7 +40,7 @@ export function AttachmentGallery({ attachments, variant = 'message', onRemove }
 
   return (
     <>
-      <div className={isComposer ? 'flex flex-wrap items-center gap-2' : 'grid grid-cols-1 gap-2 sm:grid-cols-2'}>
+      <div className={isComposer ? 'flex flex-wrap items-center gap-2' : 'flex flex-wrap justify-end gap-2'}>
         {attachments.map((attachment, index) => {
           if (attachment.type === 'image' && (attachment.previewUrl || attachment.data)) {
             const src = attachment.previewUrl || attachment.data || ''
@@ -80,18 +85,29 @@ export function AttachmentGallery({ attachments, variant = 'message', onRemove }
           return (
             <div
               key={attachment.id || `${attachment.name}-${index}`}
-              className="flex items-center gap-2 rounded-xl border border-[var(--color-border)] bg-[var(--color-surface-container-low)] px-3 py-2 text-xs text-[var(--color-text-secondary)]"
+              className={[
+                'group/file inline-flex max-w-full min-w-0 items-center gap-2 rounded-full border border-[var(--color-border)]',
+                'bg-[var(--color-surface-container-low)] text-[var(--color-text-secondary)] shadow-[0_1px_2px_rgba(0,0,0,0.04)]',
+                isComposer ? 'h-9 px-3' : 'h-9 px-3',
+              ].join(' ')}
             >
-              <span className="material-symbols-outlined text-[14px]">attach_file</span>
-              <span className="max-w-[220px] truncate">{attachment.name}</span>
+              <span className="material-symbols-outlined shrink-0 text-[17px] text-[var(--color-text-tertiary)]">
+                {attachment.lineStart ? 'chat_bubble' : 'description'}
+              </span>
+              <span className="min-w-0 max-w-[220px] truncate text-[13px] font-medium leading-none text-[var(--color-text-primary)]">
+                {attachment.name}
+                {attachment.lineStart
+                  ? `:L${attachment.lineStart}${attachment.lineEnd && attachment.lineEnd !== attachment.lineStart ? `-L${attachment.lineEnd}` : ''}`
+                  : ''}
+              </span>
               {onRemove && attachment.id && (
                 <button
                   type="button"
                   onClick={() => onRemove(attachment.id!)}
-                  className="ml-1 text-[var(--color-text-tertiary)] transition-colors hover:text-[var(--color-error)]"
+                  className="ml-0.5 flex h-5 w-5 shrink-0 items-center justify-center rounded-full text-[var(--color-text-tertiary)] transition-colors hover:text-[var(--color-text-primary)]"
                   aria-label={`Remove ${attachment.name}`}
                 >
-                  <span className="material-symbols-outlined text-[14px]">close</span>
+                  <span className="material-symbols-outlined text-[17px]">close</span>
                 </button>
               )}
             </div>

desktop/src/components/chat/ChatInput.tsx

@@ -6,6 +6,11 @@ import { useUIStore } from '../../stores/uiStore'
 import { useSessionStore } from '../../stores/sessionStore'
 import { useSessionRuntimeStore } from '../../stores/sessionRuntimeStore'
 import { useTeamStore } from '../../stores/teamStore'
+import {
+  formatWorkspaceReferencePrompt,
+  useWorkspaceChatContextStore,
+  type WorkspaceChatReference,
+} from '../../stores/workspaceChatContextStore'
 import { sessionsApi } from '../../api/sessions'
 import { PermissionModeSelector } from '../controls/PermissionModeSelector'
 import { ModelSelector } from '../controls/ModelSelector'
@@ -29,16 +34,37 @@ type Attachment = {
   id: string
   name: string
   type: 'image' | 'file'
+  path?: string
   mimeType?: string
   previewUrl?: string
   data?: string
+  lineStart?: number
+  lineEnd?: number
+  note?: string
+  quote?: string
 }
 
 type ChatInputProps = {
   variant?: 'default' | 'hero'
+  compact?: boolean
 }
 
-export function ChatInput({ variant = 'default' }: ChatInputProps) {
+const EMPTY_WORKSPACE_REFERENCES: WorkspaceChatReference[] = []
+
+function workspaceReferenceToAttachment(reference: WorkspaceChatReference): Attachment {
+  return {
+    id: reference.id,
+    name: reference.name,
+    type: 'file',
+    path: reference.path,
+    lineStart: reference.lineStart,
+    lineEnd: reference.lineEnd,
+    note: reference.note,
+    quote: reference.quote,
+  }
+}
+
+export function ChatInput({ variant = 'default', compact = false }: ChatInputProps) {
   const t = useTranslation()
   const [input, setInput] = useState('')
   const [attachments, setAttachments] = useState<Attachment[]>([])
@@ -67,13 +93,27 @@ export function ChatInput({ variant = 'default' }: ChatInputProps) {
   const memberInfo = useTeamStore((s) => activeTabId ? s.getMemberBySessionId(activeTabId) : null)
   const [gitInfo, setGitInfo] = useState<GitInfo | null>(null)
   const hasMessages = useChatStore((s) => activeTabId ? (s.sessions[activeTabId]?.messages?.length ?? 0) > 0 : false)
+  const workspaceReferences = useWorkspaceChatContextStore(
+    (s) => activeTabId ? s.referencesBySession[activeTabId] ?? EMPTY_WORKSPACE_REFERENCES : EMPTY_WORKSPACE_REFERENCES,
+  )
+  const addWorkspaceReference = useWorkspaceChatContextStore((s) => s.addReference)
+  const removeWorkspaceReference = useWorkspaceChatContextStore((s) => s.removeReference)
+  const clearWorkspaceReferences = useWorkspaceChatContextStore((s) => s.clearReferences)
 
   const isMemberSession = !!memberInfo
   const isActive = chatState !== 'idle'
   const isWorkspaceMissing = activeSession?.workDirExists === false
-  const canSubmit = !isWorkspaceMissing && (input.trim().length > 0 || (!isMemberSession && attachments.length > 0))
-  const isHeroComposer = variant === 'hero' && !isMemberSession
+  const hasWorkspaceReferences = !isMemberSession && workspaceReferences.length > 0
+  const canSubmit = !isWorkspaceMissing && (input.trim().length > 0 || (!isMemberSession && (attachments.length > 0 || hasWorkspaceReferences)))
+  const isHeroComposer = variant === 'hero' && !isMemberSession && !compact
   const resolvedWorkDir = activeSession?.workDir || gitInfo?.workDir || undefined
+  const composerAttachments = useMemo(
+    () => [
+      ...attachments,
+      ...workspaceReferences.map(workspaceReferenceToAttachment),
+    ],
+    [attachments, workspaceReferences],
+  )
 
   useEffect(() => {
     textareaRef.current?.focus()
@@ -302,7 +342,7 @@ export function ChatInput({ variant = 'default' }: ChatInputProps) {
 
   const handleSubmit = () => {
     const text = input.trim()
-    if ((!text && (!attachments.length || isMemberSession)) || isWorkspaceMissing) return
+    if ((!text && ((!attachments.length && !hasWorkspaceReferences) || isMemberSession)) || isWorkspaceMissing) return
 
     const slashUiAction = !isMemberSession && text.startsWith('/') ? resolveSlashUiAction(text.slice(1)) : null
     if (slashUiAction?.type === 'panel') {
@@ -324,16 +364,55 @@ export function ChatInput({ variant = 'default' }: ChatInputProps) {
       return
     }
 
-    const attachmentPayload: AttachmentRef[] = attachments.map((attachment) => ({
+    const workspaceReferencePrompt = !isMemberSession
+      ? formatWorkspaceReferencePrompt(workspaceReferences)
+      : ''
+    const contentForModel = [workspaceReferencePrompt, text].filter(Boolean).join('\n\n')
+    const displayContent = text || (
+      workspaceReferences.length > 0
+        ? t('chat.workspaceReferencesOnly', { count: workspaceReferences.length })
+        : ''
+    )
+    const uploadAttachmentPayload: AttachmentRef[] = attachments.map((attachment) => ({
       type: attachment.type,
       name: attachment.name,
+      path: attachment.path,
       data: attachment.data,
       mimeType: attachment.mimeType,
+      lineStart: attachment.lineStart,
+      lineEnd: attachment.lineEnd,
+      note: attachment.note,
+      quote: attachment.quote,
     }))
+    const workspaceAttachmentPayload: AttachmentRef[] = workspaceReferences.map((reference) => ({
+      type: 'file' as const,
+      name: reference.name,
+      path: reference.absolutePath ?? reference.path,
+      lineStart: reference.lineStart,
+      lineEnd: reference.lineEnd,
+      note: reference.note,
+      quote: reference.quote,
+    }))
+    const visibleAttachmentPayload: AttachmentRef[] = [
+      ...uploadAttachmentPayload,
+      ...workspaceReferences.map((reference) => ({
+        type: 'file' as const,
+        name: reference.name,
+        path: reference.path,
+        lineStart: reference.lineStart,
+        lineEnd: reference.lineEnd,
+        note: reference.note,
+        quote: reference.quote,
+      })),
+    ]
 
-    sendMessage(activeTabId!, text, attachmentPayload)
+    sendMessage(activeTabId!, contentForModel, [...uploadAttachmentPayload, ...workspaceAttachmentPayload], {
+      displayContent,
+      displayAttachments: visibleAttachmentPayload,
+    })
     setInput('')
     setAttachments([])
+    if (!isMemberSession) clearWorkspaceReferences(activeTabId!)
     setPlusMenuOpen(false)
     setSlashMenuOpen(false)
     setFileSearchOpen(false)
@@ -487,6 +566,7 @@ export function ChatInput({ variant = 'default' }: ChatInputProps) {
 
   const removeAttachment = (id: string) => {
     setAttachments((prev) => prev.filter((attachment) => attachment.id !== id))
+    if (activeTabId) removeWorkspaceReference(activeTabId, id)
   }
 
   const insertSlashCommand = () => {
@@ -517,12 +597,30 @@ export function ChatInput({ variant = 'default' }: ChatInputProps) {
   const slashCommandsLabel = isHeroComposer ? t('empty.slashCommands') : t('chat.slashCommands')
 
   return (
-    <div className={isHeroComposer ? 'bg-[var(--color-surface)] px-8 pb-4' : 'bg-[var(--color-surface)] px-4 py-4'}>
-      <div className={isHeroComposer ? 'mx-auto flex w-full max-w-3xl flex-col gap-2' : 'mx-auto max-w-[860px]'}>
+    <div
+      className={
+        isHeroComposer
+          ? 'bg-[var(--color-surface)] px-8 pb-4'
+          : compact
+            ? 'border-t border-[var(--color-border)]/70 bg-[var(--color-surface)] px-3 py-3'
+            : 'bg-[var(--color-surface)] px-4 py-4'
+      }
+    >
+      <div
+        className={
+          isHeroComposer
+            ? 'mx-auto flex w-full max-w-3xl flex-col gap-2'
+            : compact
+              ? 'mx-auto max-w-full'
+              : 'mx-auto max-w-[860px]'
+        }
+      >
         <div
           className={isHeroComposer
             ? 'glass-panel relative flex flex-col gap-3 rounded-xl p-4 transition-colors'
-            : 'glass-panel relative rounded-xl p-4 transition-colors'}
+            : compact
+              ? 'glass-panel relative rounded-xl p-3 transition-colors'
+              : 'glass-panel relative rounded-xl p-4 transition-colors'}
           onDragOver={(event) => event.preventDefault()}
           onDrop={handleDrop}
         >
@@ -531,11 +629,19 @@ export function ChatInput({ variant = 'default' }: ChatInputProps) {
               ref={fileSearchRef}
               cwd={resolvedWorkDir || ''}
               filter={atFilter}
-              onSelect={(_path, name) => {
+              onSelect={(path, name) => {
                 if (atCursorPos >= 0) {
                   // Insert name at cursor position, replacing filter text
                   const newValue = `${input.slice(0, atCursorPos)}${name}${input.slice(atCursorPos)}`
                   const newCursorPos = atCursorPos + name.length
+                  if (activeTabId) {
+                    addWorkspaceReference(activeTabId, {
+                      kind: 'file',
+                      path,
+                      absolutePath: path,
+                      name,
+                    })
+                  }
                   setInput(newValue)
                   setFileSearchOpen(false)
                   setAtFilter('')
@@ -599,12 +705,12 @@ export function ChatInput({ variant = 'default' }: ChatInputProps) {
             </div>
           )}
 
-          {attachments.length > 0 && (
+          {composerAttachments.length > 0 && (
             isHeroComposer ? (
-              <AttachmentGallery attachments={attachments} variant="composer" onRemove={removeAttachment} />
+              <AttachmentGallery attachments={composerAttachments} variant="composer" onRemove={removeAttachment} />
             ) : (
               <div className="px-3 pt-3">
-                <AttachmentGallery attachments={attachments} variant="composer" onRemove={removeAttachment} />
+                <AttachmentGallery attachments={composerAttachments} variant="composer" onRemove={removeAttachment} />
               </div>
             )
           )}
@@ -637,14 +743,18 @@ export function ChatInput({ variant = 'default' }: ChatInputProps) {
               placeholder={composerPlaceholder}
               disabled={isWorkspaceMissing}
               rows={1}
-              className="w-full resize-none bg-transparent py-2 pb-12 text-sm leading-relaxed text-[var(--color-text-primary)] outline-none placeholder:text-[var(--color-text-tertiary)] disabled:opacity-50"
+              className={`w-full resize-none bg-transparent text-sm leading-relaxed text-[var(--color-text-primary)] outline-none placeholder:text-[var(--color-text-tertiary)] disabled:opacity-50 ${
+                compact ? 'py-1.5 pb-11' : 'py-2 pb-12'
+              }`}
             />
           )}
 
           <div className={isHeroComposer
             ? 'flex items-center justify-between border-t border-[var(--color-border-separator)] pt-3'
-            : 'absolute bottom-0 left-0 right-0 flex items-center justify-between border-t border-[var(--color-border-separator)] px-3 py-3'}>
-            <div className="flex items-center gap-2">
+            : `absolute bottom-0 left-0 right-0 flex items-center justify-between border-t border-[var(--color-border-separator)] ${
+              compact ? 'gap-2 px-2.5 py-2' : 'px-3 py-3'
+            }`}>
+            <div className="flex min-w-0 items-center gap-2">
               {!isMemberSession && (
                 <>
                   <div ref={plusMenuRef} className="relative">
@@ -679,20 +789,30 @@ export function ChatInput({ variant = 'default' }: ChatInputProps) {
                     )}
                   </div>
 
-                  <PermissionModeSelector />
+                  <PermissionModeSelector compact={compact} />
                 </>
               )}
             </div>
 
-            <div className="flex items-center gap-2">
+            <div className="flex min-w-0 items-center gap-2">
               {!isMemberSession && activeTabId && (
-                <ModelSelector runtimeKey={activeTabId} disabled={isActive} />
+                <ModelSelector runtimeKey={activeTabId} disabled={isActive} compact={compact} />
               )}
               <button
                 onClick={!isMemberSession && isActive ? () => stopGeneration(activeTabId!) : handleSubmit}
                 disabled={!isMemberSession && isActive ? false : !canSubmit}
-                title={!isMemberSession && isActive ? t('chat.stopTitle') : undefined}
-                className={`flex w-[112px] items-center justify-center gap-1 rounded-lg px-3 py-1.5 text-xs font-semibold transition-all hover:brightness-105 disabled:opacity-30 ${
+                title={
+                  !isMemberSession && isActive
+                    ? t('chat.stopTitle')
+                    : compact
+                      ? isMemberSession
+                        ? t('common.send')
+                        : t('common.run')
+                      : undefined
+                }
+                className={`flex items-center justify-center gap-1 rounded-lg text-xs font-semibold transition-all hover:brightness-105 disabled:opacity-30 ${
+                  compact ? 'h-8 w-8 px-0 py-0' : 'w-[112px] px-3 py-1.5'
+                } ${
                   !isMemberSession && isActive
                     ? 'bg-[var(--color-error-container)] text-[var(--color-on-error-container)]'
                     : 'bg-[image:var(--gradient-btn-primary)] text-[var(--color-btn-primary-fg)] shadow-[var(--shadow-button-primary)]'
@@ -701,7 +821,7 @@ export function ChatInput({ variant = 'default' }: ChatInputProps) {
                 <span className="material-symbols-outlined text-[14px]">
                   {!isMemberSession && isActive ? 'stop' : 'arrow_forward'}
                 </span>
-                {!isMemberSession && isActive ? t('common.stop') : isMemberSession ? t('common.send') : t('common.run')}
+                {!compact && (!isMemberSession && isActive ? t('common.stop') : isMemberSession ? t('common.send') : t('common.run'))}
               </button>
             </div>
           </div>
@@ -710,12 +830,13 @@ export function ChatInput({ variant = 'default' }: ChatInputProps) {
         <input ref={fileInputRef} type="file" multiple className="hidden" onChange={handleFileSelect} />
 
         {!isMemberSession && (
-          <div className="mt-3 px-1">
+          <div className={compact ? 'mt-2 flex min-w-0 justify-center px-1' : 'mt-3 px-1'}>
             {hasMessages ? (
               <ProjectContextChip
                 workDir={resolvedWorkDir}
                 repoName={gitInfo?.repoName || null}
                 branch={gitInfo?.branch || null}
+                compact={compact}
               />
             ) : (
               <DirectoryPicker

desktop/src/components/chat/ComputerUsePermissionModal.test.tsx

@@ -73,12 +73,14 @@ vi.mock('../../api/computerUse', () => ({
 }))
 
 import { useChatStore } from '../../stores/chatStore'
+import { useSettingsStore } from '../../stores/settingsStore'
 import { ComputerUsePermissionModal } from './ComputerUsePermissionModal'
 
 describe('ComputerUsePermissionModal', () => {
   beforeEach(() => {
     sendMock.mockReset()
     openSettingsMock.mockReset()
+    useSettingsStore.setState({ locale: 'en' })
     useChatStore.setState({ sessions: {} })
   })
 

desktop/src/components/chat/CurrentTurnChangeCard.tsx

@@ -0,0 +1,182 @@
+import { useCallback, useMemo, useState } from 'react'
+import { sessionsApi, type SessionRewindResponse } from '../../api/sessions'
+import { useTranslation } from '../../i18n'
+import { WorkspaceDiffSurface } from '../workspace/WorkspaceCodeSurface'
+
+type DiffPreviewState = {
+  loading: boolean
+  diff?: string
+  error?: string
+}
+
+type CurrentTurnChangeCardProps = {
+  sessionId: string
+  preview: SessionRewindResponse
+  workDir: string | null
+  error: string | null
+  isUndoing: boolean
+  onUndo: () => void
+}
+
+export function CurrentTurnChangeCard({
+  sessionId,
+  preview,
+  workDir,
+  error,
+  isUndoing,
+  onUndo,
+}: CurrentTurnChangeCardProps) {
+  const t = useTranslation()
+  const [expandedPath, setExpandedPath] = useState<string | null>(null)
+  const [diffByPath, setDiffByPath] = useState<Record<string, DiffPreviewState>>({})
+
+  const files = useMemo(
+    () => preview.code.filesChanged.map((filePath) => relativizeWorkspacePath(filePath, workDir)),
+    [preview.code.filesChanged, workDir],
+  )
+
+  const toggleDiff = useCallback((filePath: string) => {
+    const nextExpandedPath = expandedPath === filePath ? null : filePath
+    setExpandedPath(nextExpandedPath)
+    if (!nextExpandedPath || diffByPath[filePath]?.diff || diffByPath[filePath]?.loading) {
+      return
+    }
+
+    setDiffByPath((current) => ({
+      ...current,
+      [filePath]: { loading: true },
+    }))
+
+    void sessionsApi
+      .getWorkspaceDiff(sessionId, filePath)
+      .then((result) => {
+        setDiffByPath((current) => ({
+          ...current,
+          [filePath]: {
+            loading: false,
+            diff: result.state === 'ok' ? result.diff || '' : undefined,
+            error: result.state === 'ok'
+              ? undefined
+              : result.error || t('chat.turnChangesDiffUnavailable'),
+          },
+        }))
+      })
+      .catch((diffError) => {
+        setDiffByPath((current) => ({
+          ...current,
+          [filePath]: {
+            loading: false,
+            error: diffError instanceof Error
+              ? diffError.message
+              : String(diffError),
+          },
+        }))
+      })
+  }, [diffByPath, expandedPath, sessionId, t])
+
+  return (
+    <section
+      className="mx-auto mb-5 w-full max-w-[860px] overflow-hidden rounded-[var(--radius-xl)] border border-[var(--color-border)] bg-[var(--color-surface)] shadow-sm"
+      aria-label={t('chat.turnChangesCardLabel')}
+    >
+      <div className="flex items-center justify-between gap-3 border-b border-[var(--color-border)] bg-[var(--color-surface-container-low)] px-4 py-3">
+        <div className="min-w-0">
+          <div className="flex flex-wrap items-baseline gap-2">
+            <span className="text-sm font-semibold text-[var(--color-text-primary)]">
+              {t('chat.turnChangesTitle', { count: files.length })}
+            </span>
+            <span className="font-mono text-sm font-semibold text-[var(--color-success)]">
+              +{preview.code.insertions}
+            </span>
+            <span className="font-mono text-sm font-semibold text-[var(--color-error)]">
+              -{preview.code.deletions}
+            </span>
+          </div>
+          <div className="mt-0.5 text-xs text-[var(--color-text-tertiary)]">
+            {t('chat.turnChangesSubtitle')}
+          </div>
+        </div>
+
+        <button
+          type="button"
+          onClick={onUndo}
+          disabled={isUndoing}
+          aria-label={t('chat.turnChangesUndoAria')}
+          className="inline-flex h-8 shrink-0 items-center gap-1.5 rounded-[var(--radius-md)] border border-[var(--color-border)] bg-[var(--color-surface)] px-3 text-xs font-medium text-[var(--color-text-secondary)] transition-colors hover:border-[var(--color-brand)]/40 hover:text-[var(--color-text-primary)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-brand)]/35 disabled:cursor-not-allowed disabled:opacity-50"
+        >
+          <span className="material-symbols-outlined text-[15px]">undo</span>
+          {isUndoing ? t('chat.turnChangesUndoing') : t('chat.turnChangesUndo')}
+        </button>
+      </div>
+
+      <div className="divide-y divide-[var(--color-border)]">
+        {files.map((filePath) => {
+          const isExpanded = expandedPath === filePath
+          const diffState = diffByPath[filePath]
+          return (
+            <div key={filePath}>
+              <button
+                type="button"
+                onClick={() => toggleDiff(filePath)}
+                aria-label={t(
+                  isExpanded ? 'chat.turnChangesHideDiffAria' : 'chat.turnChangesShowDiffAria',
+                  { path: filePath },
+                )}
+                className="flex min-h-11 w-full items-center gap-3 px-4 text-left text-sm text-[var(--color-text-primary)] transition-colors hover:bg-[var(--color-surface-hover)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-[var(--color-brand)]/35"
+              >
+                <span className="material-symbols-outlined shrink-0 text-[17px] text-[var(--color-text-tertiary)]">
+                  {isExpanded ? 'keyboard_arrow_down' : 'chevron_right'}
+                </span>
+                <span className="min-w-0 flex-1 truncate font-mono text-[13px]">
+                  {filePath}
+                </span>
+              </button>
+
+              {isExpanded && (
+                <div className="border-t border-[var(--color-border)] bg-[var(--color-surface-container-lowest)] px-4 py-3">
+                  {diffState?.loading ? (
+                    <div className="text-xs text-[var(--color-text-tertiary)]">
+                      {t('chat.turnChangesDiffLoading')}
+                    </div>
+                  ) : diffState?.error ? (
+                    <div className="text-xs text-[var(--color-error)]">
+                      {diffState.error}
+                    </div>
+                  ) : diffState?.diff ? (
+                    <WorkspaceDiffSurface
+                      value={diffState.diff}
+                      path={filePath}
+                      className="max-h-[430px] overflow-auto rounded-[var(--radius-md)] border border-[var(--color-border)] bg-[var(--color-code-bg)]"
+                    />
+                  ) : (
+                    <div className="text-xs text-[var(--color-text-tertiary)]">
+                      {t('chat.turnChangesDiffUnavailable')}
+                    </div>
+                  )}
+                </div>
+              )}
+            </div>
+          )
+        })}
+      </div>
+
+      {error && (
+        <div className="border-t border-[var(--color-error)]/20 bg-[var(--color-error-container)]/18 px-4 py-3 text-xs text-[var(--color-error)]">
+          {error}
+        </div>
+      )}
+    </section>
+  )
+}
+
+function relativizeWorkspacePath(filePath: string, workDir: string | null): string {
+  const normalizedPath = filePath.replace(/\\/g, '/')
+  if (!workDir || !normalizedPath.startsWith('/')) return normalizedPath
+
+  const normalizedWorkDir = workDir.replace(/\\/g, '/').replace(/\/+$/, '')
+  if (normalizedPath === normalizedWorkDir) return ''
+  if (normalizedPath.startsWith(`${normalizedWorkDir}/`)) {
+    return normalizedPath.slice(normalizedWorkDir.length + 1)
+  }
+  return normalizedPath
+}

desktop/src/components/chat/FileSearchMenu.test.tsx

@@ -4,6 +4,7 @@ import '@testing-library/jest-dom'
 import { FileSearchMenu } from './FileSearchMenu'
 import { ApiError } from '../../api/client'
 import { filesystemApi } from '../../api/filesystem'
+import { useSettingsStore } from '../../stores/settingsStore'
 
 vi.mock('../../api/filesystem', () => ({
   filesystemApi: {
@@ -15,6 +16,7 @@ vi.mock('../../api/filesystem', () => ({
 describe('FileSearchMenu', () => {
   beforeEach(() => {
     vi.clearAllMocks()
+    useSettingsStore.setState({ locale: 'en' })
   })
 
   it('shows an explicit error when directory browsing is denied', async () => {

desktop/src/components/chat/MessageActionBar.tsx

@@ -3,22 +3,17 @@ import { CopyButton } from '../shared/CopyButton'
 type Props = {
   copyText?: string
   copyLabel: string
-  onRewind?: () => void
-  rewindLabel?: string
   align?: 'start' | 'end'
 }
 
 export function MessageActionBar({
   copyText,
   copyLabel,
-  onRewind,
-  rewindLabel = 'Rewind to here',
   align = 'start',
 }: Props) {
   const hasCopy = Boolean(copyText?.trim())
-  const hasRewind = Boolean(onRewind)
 
-  if (!hasCopy && !hasRewind) return null
+  if (!hasCopy) return null
 
   return (
     <div
@@ -29,27 +24,13 @@ export function MessageActionBar({
       }`}
     >
       <div className="flex items-center gap-1.5">
-        {hasRewind && (
-          <button
-            type="button"
-            onClick={onRewind}
-            aria-label={rewindLabel}
-            title={rewindLabel}
-            className="inline-flex min-h-7 items-center gap-1 rounded-full border border-[var(--color-border)]/70 bg-[var(--color-surface-container-low)] px-2.5 text-[11px] font-medium text-[var(--color-text-tertiary)] transition-colors hover:border-[var(--color-brand)]/35 hover:text-[var(--color-text-primary)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-brand)]/35"
-          >
-            <span className="material-symbols-outlined text-[14px]">undo</span>
-            <span className="hidden min-[920px]:inline">Rewind</span>
-          </button>
-        )}
-        {hasCopy && (
-          <CopyButton
-            text={copyText!}
-            label={copyLabel}
-            displayLabel="Copy"
-            displayCopiedLabel="Copied"
-            className="inline-flex min-h-7 items-center rounded-full border border-[var(--color-border)]/70 bg-[var(--color-surface-container-low)] px-2.5 text-[11px] font-medium text-[var(--color-text-tertiary)] transition-colors hover:border-[var(--color-brand)]/35 hover:text-[var(--color-text-primary)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-brand)]/35"
-          />
-        )}
+        <CopyButton
+          text={copyText!}
+          label={copyLabel}
+          displayLabel="Copy"
+          displayCopiedLabel="Copied"
+          className="inline-flex min-h-7 items-center rounded-full border border-[var(--color-border)]/70 bg-[var(--color-surface-container-low)] px-2.5 text-[11px] font-medium text-[var(--color-text-tertiary)] transition-colors hover:border-[var(--color-brand)]/35 hover:text-[var(--color-text-primary)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-brand)]/35"
+        />
       </div>
     </div>
   )

desktop/src/components/chat/MessageList.test.tsx

@@ -563,7 +563,7 @@ describe('MessageList nested tool calls', () => {
     expect(assistantShell?.className).not.toContain('ml-10')
   })
 
-  it('opens a rewind preview modal for user messages', async () => {
+  it('does not expose the old message-level rewind action', async () => {
     vi.spyOn(sessionsApi, 'rewind').mockResolvedValue({
       target: {
         targetUserMessageId: 'user-1',
@@ -575,11 +575,19 @@ describe('MessageList nested tool calls', () => {
       },
       code: {
         available: true,
-        filesChanged: ['src/example.ts'],
-        insertions: 6,
-        deletions: 2,
+        filesChanged: ['src/App.tsx'],
+        insertions: 4,
+        deletions: 1,
       },
     })
+    vi.spyOn(sessionsApi, 'getWorkspaceStatus').mockResolvedValue({
+      state: 'ok',
+      workDir: '/tmp/example-project',
+      repoName: 'example-project',
+      branch: null,
+      isGitRepo: false,
+      changedFiles: [],
+    })
 
     useChatStore.setState({
       sessions: {
@@ -588,9 +596,15 @@ describe('MessageList nested tool calls', () => {
             {
               id: 'user-1',
               type: 'user_text',
-              content: '回到这一步重做',
+              content: '做一个页面',
               timestamp: 1,
             },
+            {
+              id: 'assistant-1',
+              type: 'assistant_text',
+              content: 'done',
+              timestamp: 2,
+            },
           ],
         }),
       },
@@ -598,21 +612,11 @@ describe('MessageList nested tool calls', () => {
 
     render(<MessageList />)
 
-    fireEvent.click(screen.getByRole('button', { name: 'Rewind to here' }))
-
-    const dialog = await screen.findByRole('dialog')
-    expect(within(dialog).getByText('Rewind Conversation')).toBeTruthy()
-    expect(within(dialog).getByText('回到这一步重做')).toBeTruthy()
-    expect(within(dialog).getByText('src/example.ts')).toBeTruthy()
-    expect(sessionsApi.rewind).toHaveBeenCalledWith(ACTIVE_TAB, {
-      targetUserMessageId: 'user-1',
-      userMessageIndex: 0,
-      expectedContent: '回到这一步重做',
-      dryRun: true,
-    })
+    expect(await screen.findByRole('button', { name: 'Undo current turn changes' })).toBeTruthy()
+    expect(screen.queryByRole('button', { name: 'Rewind to here' })).toBeNull()
   })
 
-  it('confirms rewind with the selected message id and prompt guard', async () => {
+  it('shows a current-turn change card from checkpoint preview', async () => {
     vi.spyOn(sessionsApi, 'rewind').mockResolvedValue({
       target: {
         targetUserMessageId: 'user-2',
@@ -623,18 +627,22 @@ describe('MessageList nested tool calls', () => {
         messagesRemoved: 2,
       },
       code: {
-        available: false,
-        filesChanged: [],
-        insertions: 0,
-        deletions: 0,
+        available: true,
+        filesChanged: ['src/App.tsx', 'src/lib/api.ts'],
+        insertions: 12,
+        deletions: 4,
       },
     })
-    const reloadHistory = vi.fn().mockResolvedValue(undefined)
-    const queueComposerPrefill = vi.fn()
+    vi.spyOn(sessionsApi, 'getWorkspaceStatus').mockResolvedValue({
+      state: 'ok',
+      workDir: '/tmp/example-project',
+      repoName: 'example-project',
+      branch: null,
+      isGitRepo: false,
+      changedFiles: [],
+    })
 
     useChatStore.setState({
-      reloadHistory,
-      queueComposerPrefill,
       sessions: {
         [ACTIVE_TAB]: makeSessionState({
           messages: [
@@ -654,8 +662,15 @@ describe('MessageList nested tool calls', () => {
               id: 'user-2',
               type: 'user_text',
               content: '第二段',
+              modelContent: '@"/tmp/example-project/src/App.tsx" 第二段',
               timestamp: 3,
             },
+            {
+              id: 'assistant-2',
+              type: 'assistant_text',
+              content: 'done',
+              timestamp: 4,
+            },
           ],
         }),
       },
@@ -663,25 +678,348 @@ describe('MessageList nested tool calls', () => {
 
     render(<MessageList />)
 
-    const buttons = screen.getAllByRole('button', { name: 'Rewind to here' })
-    fireEvent.click(buttons[1]!)
-    const dialog = await screen.findByRole('dialog')
-    fireEvent.click(within(dialog).getByRole('button', { name: /Rewind here/ }))
+    expect(await screen.findByText('2 files changed')).toBeTruthy()
+    expect(screen.getByLabelText('Current turn changed files').className).toContain('w-full max-w-[860px]')
+    expect(screen.getByText('+12')).toBeTruthy()
+    expect(screen.getByText('-4')).toBeTruthy()
+    expect(screen.getByText('src/App.tsx')).toBeTruthy()
+    expect(screen.getByText('src/lib/api.ts')).toBeTruthy()
+    expect(sessionsApi.rewind).toHaveBeenCalledWith(ACTIVE_TAB, {
+      targetUserMessageId: 'user-2',
+      userMessageIndex: 1,
+      expectedContent: '@"/tmp/example-project/src/App.tsx" 第二段',
+      dryRun: true,
+    })
+  })
+
+  it('expands a current-turn changed file diff', async () => {
+    vi.spyOn(sessionsApi, 'rewind').mockResolvedValue({
+      target: {
+        targetUserMessageId: 'user-1',
+        userMessageIndex: 0,
+        userMessageCount: 1,
+      },
+      conversation: {
+        messagesRemoved: 2,
+      },
+      code: {
+        available: true,
+        filesChanged: ['src/App.tsx'],
+        insertions: 1,
+        deletions: 1,
+      },
+    })
+    vi.spyOn(sessionsApi, 'getWorkspaceStatus').mockResolvedValue({
+      state: 'ok',
+      workDir: '/tmp/example-project',
+      repoName: 'example-project',
+      branch: null,
+      isGitRepo: false,
+      changedFiles: [],
+    })
+    vi.spyOn(sessionsApi, 'getWorkspaceDiff').mockResolvedValue({
+      state: 'ok',
+      path: 'src/App.tsx',
+      diff: 'diff --session a/src/App.tsx b/src/App.tsx\n-old\n+new',
+    })
+
+    useChatStore.setState({
+      sessions: {
+        [ACTIVE_TAB]: makeSessionState({
+          messages: [
+            {
+              id: 'user-1',
+              type: 'user_text',
+              content: '改一下',
+              timestamp: 1,
+            },
+            {
+              id: 'assistant-1',
+              type: 'assistant_text',
+              content: 'done',
+              timestamp: 2,
+            },
+          ],
+        }),
+      },
+    })
+
+    render(<MessageList />)
+
+    fireEvent.click(await screen.findByRole('button', { name: 'Show diff for src/App.tsx' }))
+
+    const diffSurface = await screen.findByTestId('workspace-code')
+    expect(diffSurface.textContent).toContain('+new')
+    expect(sessionsApi.getWorkspaceDiff).toHaveBeenCalledWith(ACTIVE_TAB, 'src/App.tsx')
+  })
+
+  it('confirms before undoing the current turn from the change card', async () => {
+    vi.spyOn(sessionsApi, 'rewind')
+      .mockResolvedValueOnce({
+        target: {
+          targetUserMessageId: 'user-1',
+          userMessageIndex: 0,
+          userMessageCount: 1,
+        },
+        conversation: {
+          messagesRemoved: 2,
+        },
+        code: {
+          available: true,
+          filesChanged: ['src/App.tsx'],
+          insertions: 1,
+          deletions: 0,
+        },
+      })
+      .mockResolvedValueOnce({
+        target: {
+          targetUserMessageId: 'user-1',
+          userMessageIndex: 0,
+          userMessageCount: 1,
+        },
+        conversation: {
+          messagesRemoved: 2,
+          removedMessageIds: ['user-1', 'assistant-1'],
+        },
+        code: {
+          available: true,
+          filesChanged: ['src/App.tsx'],
+          insertions: 1,
+          deletions: 0,
+        },
+      })
+    vi.spyOn(sessionsApi, 'getWorkspaceStatus').mockResolvedValue({
+      state: 'ok',
+      workDir: '/tmp/example-project',
+      repoName: 'example-project',
+      branch: null,
+      isGitRepo: false,
+      changedFiles: [],
+    })
+    const reloadHistory = vi.fn().mockResolvedValue(undefined)
+    const queueComposerPrefill = vi.fn()
+
+    useChatStore.setState({
+      reloadHistory,
+      queueComposerPrefill,
+      sessions: {
+        [ACTIVE_TAB]: makeSessionState({
+          messages: [
+            {
+              id: 'user-1',
+              type: 'user_text',
+              content: '做一个页面',
+              timestamp: 1,
+            },
+            {
+              id: 'assistant-1',
+              type: 'assistant_text',
+              content: 'done',
+              timestamp: 2,
+            },
+          ],
+        }),
+      },
+    })
+
+    render(<MessageList />)
+
+    fireEvent.click(await screen.findByRole('button', { name: 'Undo current turn changes' }))
+
+    expect(sessionsApi.rewind).toHaveBeenCalledTimes(1)
+    const dialog = await screen.findByRole('dialog', { name: 'Undo current turn?' })
+    expect(within(dialog).getByText('This will rewind the latest assistant response and restore tracked files for this turn.')).toBeTruthy()
+
+    fireEvent.click(within(dialog).getByRole('button', { name: 'Undo current turn' }))
+
+    await waitFor(() => {
+      expect(sessionsApi.rewind).toHaveBeenLastCalledWith(ACTIVE_TAB, {
+        targetUserMessageId: 'user-1',
+        userMessageIndex: 0,
+        expectedContent: '做一个页面',
+      })
+    })
+    expect(reloadHistory).toHaveBeenCalledWith(ACTIVE_TAB)
+    expect(queueComposerPrefill).toHaveBeenCalledWith(ACTIVE_TAB, {
+      text: '做一个页面',
+      attachments: undefined,
+    })
+  })
+
+  it('undoes only the latest completed turn when earlier turns also changed files', async () => {
+    vi.spyOn(sessionsApi, 'rewind')
+      .mockResolvedValueOnce({
+        target: {
+          targetUserMessageId: 'user-2',
+          userMessageIndex: 1,
+          userMessageCount: 2,
+        },
+        conversation: {
+          messagesRemoved: 2,
+        },
+        code: {
+          available: true,
+          filesChanged: ['src/second.ts'],
+          insertions: 7,
+          deletions: 2,
+        },
+      })
+      .mockResolvedValueOnce({
+        target: {
+          targetUserMessageId: 'user-2',
+          userMessageIndex: 1,
+          userMessageCount: 2,
+        },
+        conversation: {
+          messagesRemoved: 2,
+          removedMessageIds: ['user-2', 'assistant-2'],
+        },
+        code: {
+          available: true,
+          filesChanged: ['src/second.ts'],
+          insertions: 7,
+          deletions: 2,
+        },
+      })
+    vi.spyOn(sessionsApi, 'getWorkspaceStatus').mockResolvedValue({
+      state: 'ok',
+      workDir: '/tmp/example-project',
+      repoName: 'example-project',
+      branch: null,
+      isGitRepo: false,
+      changedFiles: [],
+    })
+    const reloadHistory = vi.fn().mockResolvedValue(undefined)
+    const queueComposerPrefill = vi.fn()
+
+    useChatStore.setState({
+      reloadHistory,
+      queueComposerPrefill,
+      sessions: {
+        [ACTIVE_TAB]: makeSessionState({
+          messages: [
+            {
+              id: 'user-1',
+              type: 'user_text',
+              content: '第一轮需求',
+              timestamp: 1,
+            },
+            {
+              id: 'assistant-1',
+              type: 'assistant_text',
+              content: 'first done',
+              timestamp: 2,
+            },
+            {
+              id: 'user-2',
+              type: 'user_text',
+              content: '第二轮需求',
+              timestamp: 3,
+            },
+            {
+              id: 'assistant-2',
+              type: 'assistant_text',
+              content: 'second done',
+              timestamp: 4,
+            },
+          ],
+        }),
+      },
+    })
+
+    render(<MessageList />)
+
+    expect(await screen.findByText('1 files changed')).toBeTruthy()
+    expect(screen.getByText('src/second.ts')).toBeTruthy()
+    expect(sessionsApi.rewind).toHaveBeenCalledWith(ACTIVE_TAB, {
+      targetUserMessageId: 'user-2',
+      userMessageIndex: 1,
+      expectedContent: '第二轮需求',
+      dryRun: true,
+    })
+
+    fireEvent.click(screen.getByRole('button', { name: 'Undo current turn changes' }))
+    const dialog = await screen.findByRole('dialog', { name: 'Undo current turn?' })
+    fireEvent.click(within(dialog).getByRole('button', { name: 'Undo current turn' }))
 
     await waitFor(() => {
       expect(sessionsApi.rewind).toHaveBeenLastCalledWith(ACTIVE_TAB, {
         targetUserMessageId: 'user-2',
         userMessageIndex: 1,
-        expectedContent: '第二段',
+        expectedContent: '第二轮需求',
       })
     })
     expect(reloadHistory).toHaveBeenCalledWith(ACTIVE_TAB)
     expect(queueComposerPrefill).toHaveBeenCalledWith(ACTIVE_TAB, {
-      text: '第二段',
+      text: '第二轮需求',
       attachments: undefined,
     })
   })
 
+  it('does not show a stale current-turn change card when the latest completed turn has no files', async () => {
+    vi.spyOn(sessionsApi, 'rewind').mockResolvedValue({
+      target: {
+        targetUserMessageId: 'user-2',
+        userMessageIndex: 1,
+        userMessageCount: 2,
+      },
+      conversation: {
+        messagesRemoved: 2,
+      },
+      code: {
+        available: true,
+        filesChanged: [],
+        insertions: 0,
+        deletions: 0,
+      },
+    })
+
+    useChatStore.setState({
+      sessions: {
+        [ACTIVE_TAB]: makeSessionState({
+          messages: [
+            {
+              id: 'user-1',
+              type: 'user_text',
+              content: '第一轮改文件',
+              timestamp: 1,
+            },
+            {
+              id: 'assistant-1',
+              type: 'assistant_text',
+              content: 'first done',
+              timestamp: 2,
+            },
+            {
+              id: 'user-2',
+              type: 'user_text',
+              content: '第二轮只解释',
+              timestamp: 3,
+            },
+            {
+              id: 'assistant-2',
+              type: 'assistant_text',
+              content: 'second done',
+              timestamp: 4,
+            },
+          ],
+        }),
+      },
+    })
+
+    render(<MessageList />)
+
+    await waitFor(() => {
+      expect(sessionsApi.rewind).toHaveBeenCalledWith(ACTIVE_TAB, {
+        targetUserMessageId: 'user-2',
+        userMessageIndex: 1,
+        expectedContent: '第二轮只解释',
+        dryRun: true,
+      })
+    })
+    expect(screen.queryByLabelText('Current turn changed files')).toBeNull()
+  })
+
   it('shows raw startup details under translated CLI startup errors', () => {
     useChatStore.setState({
       sessions: {

desktop/src/components/chat/MessageList.tsx

@@ -17,9 +17,9 @@ import { PermissionDialog } from './PermissionDialog'
 import { AskUserQuestion } from './AskUserQuestion'
 import { StreamingIndicator } from './StreamingIndicator'
 import { InlineTaskSummary } from './InlineTaskSummary'
+import { CurrentTurnChangeCard } from './CurrentTurnChangeCard'
 import type { AgentTaskNotification, UIMessage } from '../../types/chat'
-import { Modal } from '../shared/Modal'
-import { Button } from '../shared/Button'
+import { ConfirmDialog } from '../shared/ConfirmDialog'
 
 type ToolCall = Extract<UIMessage, { type: 'tool_use' }>
 type ToolResult = Extract<UIMessage, { type: 'tool_result' }>
@@ -34,6 +34,20 @@ type RenderModel = {
   childToolCallsByParent: Map<string, ToolCall[]>
 }
 
+type RewindTurnTarget = {
+  messageId: string
+  userMessageIndex: number
+  content: string
+  expectedContent: string
+  attachments?: Extract<UIMessage, { type: 'user_text' }>['attachments']
+}
+
+type CurrentTurnPreview = {
+  target: RewindTurnTarget
+  preview: SessionRewindResponse
+  workDir: string | null
+}
+
 function appendChildToolCall(
   childToolCallsByParent: Map<string, ToolCall[]>,
   parentToolUseId: string,
@@ -104,8 +118,45 @@ export function buildRenderModel(messages: UIMessage[]): RenderModel {
   return { renderItems: items, toolResultMap, childToolCallsByParent }
 }
 
+export function getLatestCompletedTurnTarget(messages: UIMessage[]): RewindTurnTarget | null {
+  let userMessageIndex = -1
+  let latestTarget: (RewindTurnTarget & { messageOffset: number }) | null = null
+
+  for (let messageOffset = 0; messageOffset < messages.length; messageOffset += 1) {
+    const message = messages[messageOffset]
+    if (!message || message.type !== 'user_text' || message.pending) continue
+    userMessageIndex += 1
+    latestTarget = {
+      messageId: message.id,
+      userMessageIndex,
+      content: message.content,
+      expectedContent: message.modelContent ?? message.content,
+      attachments: message.attachments,
+      messageOffset,
+    }
+  }
+
+  if (!latestTarget) return null
+
+  const hasResponseAfterTarget = messages
+    .slice(latestTarget.messageOffset + 1)
+    .some((message) =>
+      message.type === 'assistant_text' ||
+      message.type === 'tool_use' ||
+      message.type === 'tool_result' ||
+      message.type === 'error' ||
+      message.type === 'task_summary',
+    )
+
+  if (!hasResponseAfterTarget) return null
+
+  const { messageOffset: _messageOffset, ...target } = latestTarget
+  return target
+}
+
 type MessageListProps = {
   sessionId?: string | null
+  compact?: boolean
 }
 
 const AUTO_SCROLL_BOTTOM_THRESHOLD_PX = 48
@@ -117,7 +168,7 @@ function isNearScrollBottom(element: HTMLElement) {
   )
 }
 
-export function MessageList({ sessionId }: MessageListProps = {}) {
+export function MessageList({ sessionId, compact = false }: MessageListProps = {}) {
   const activeTabId = useTabStore((s) => s.activeTabId)
   const resolvedSessionId = sessionId ?? activeTabId
   const sessionState = useChatStore((s) =>
@@ -140,16 +191,11 @@ export function MessageList({ sessionId }: MessageListProps = {}) {
   const shouldAutoScrollRef = useRef(true)
   const lastSessionIdRef = useRef<string | null | undefined>(resolvedSessionId)
   const t = useTranslation()
-  const [rewindTarget, setRewindTarget] = useState<{
-    messageId: string
-    userMessageIndex: number
-    content: string
-    attachments?: Extract<UIMessage, { type: 'user_text' }>['attachments']
-  } | null>(null)
-  const [rewindPreview, setRewindPreview] = useState<SessionRewindResponse | null>(null)
-  const [rewindError, setRewindError] = useState<string | null>(null)
-  const [isLoadingPreview, setIsLoadingPreview] = useState(false)
-  const [isExecutingRewind, setIsExecutingRewind] = useState(false)
+  const [currentTurnPreview, setCurrentTurnPreview] = useState<CurrentTurnPreview | null>(null)
+  const [currentTurnError, setCurrentTurnError] = useState<string | null>(null)
+  const [isLoadingCurrentTurnPreview, setIsLoadingCurrentTurnPreview] = useState(false)
+  const [isUndoingCurrentTurn, setIsUndoingCurrentTurn] = useState(false)
+  const [currentTurnUndoConfirmOpen, setCurrentTurnUndoConfirmOpen] = useState(false)
 
   const updateAutoScrollState = useCallback(() => {
     const container = scrollContainerRef.current
@@ -168,25 +214,50 @@ export function MessageList({ sessionId }: MessageListProps = {}) {
     bottomRef.current?.scrollIntoView?.({ behavior: 'smooth' })
   }, [messages.length, resolvedSessionId, streamingText])
 
+  const { toolResultMap, childToolCallsByParent, renderItems } = useMemo(
+    () => buildRenderModel(messages),
+    [messages],
+  )
+  const latestTurnTarget = useMemo(() => getLatestCompletedTurnTarget(messages), [messages])
+
   useEffect(() => {
-    if (!resolvedSessionId || !rewindTarget) return
+    if (
+      !resolvedSessionId ||
+      !latestTurnTarget ||
+      chatState !== 'idle' ||
+      isMemberSession
+    ) {
+      setCurrentTurnPreview(null)
+      setCurrentTurnError(null)
+      setIsLoadingCurrentTurnPreview(false)
+      return
+    }
 
     let cancelled = false
-    setIsLoadingPreview(true)
-    setRewindPreview(null)
-    setRewindError(null)
+    setIsLoadingCurrentTurnPreview(true)
+    setCurrentTurnPreview(null)
+    setCurrentTurnError(null)
 
-    void sessionsApi
-      .rewind(resolvedSessionId, {
-        targetUserMessageId: rewindTarget.messageId,
-        userMessageIndex: rewindTarget.userMessageIndex,
-        expectedContent: rewindTarget.content,
+    Promise.all([
+      sessionsApi.rewind(resolvedSessionId, {
+        targetUserMessageId: latestTurnTarget.messageId,
+        userMessageIndex: latestTurnTarget.userMessageIndex,
+        expectedContent: latestTurnTarget.expectedContent,
         dryRun: true,
-      })
-      .then((preview) => {
-        if (!cancelled) {
-          setRewindPreview(preview)
+      }),
+      sessionsApi.getWorkspaceStatus(resolvedSessionId).catch(() => null),
+    ])
+      .then(([preview, workspaceStatus]) => {
+        if (cancelled) return
+        if (!preview.code.available || preview.code.filesChanged.length === 0) {
+          setCurrentTurnPreview(null)
+          return
         }
+        setCurrentTurnPreview({
+          target: latestTurnTarget,
+          preview,
+          workDir: workspaceStatus?.workDir ?? null,
+        })
       })
       .catch((error) => {
         if (cancelled) return
@@ -198,37 +269,25 @@ export function MessageList({ sessionId }: MessageListProps = {}) {
             : error instanceof Error
               ? error.message
               : String(error)
-        setRewindError(message)
+        setCurrentTurnError(message)
       })
       .finally(() => {
         if (!cancelled) {
-          setIsLoadingPreview(false)
+          setIsLoadingCurrentTurnPreview(false)
         }
       })
 
     return () => {
       cancelled = true
     }
-  }, [resolvedSessionId, rewindTarget])
+  }, [chatState, isMemberSession, latestTurnTarget, resolvedSessionId])
 
-  const { toolResultMap, childToolCallsByParent, renderItems } = useMemo(
-    () => buildRenderModel(messages),
-    [messages],
-  )
+  const handleUndoCurrentTurn = useCallback(async () => {
+    if (!resolvedSessionId || !currentTurnPreview || isUndoingCurrentTurn) return
 
-  const closeRewindModal = useCallback(() => {
-    if (isExecutingRewind) return
-    setRewindTarget(null)
-    setRewindPreview(null)
-    setRewindError(null)
-    setIsLoadingPreview(false)
-  }, [isExecutingRewind])
-
-  const handleConfirmRewind = useCallback(async () => {
-    if (!resolvedSessionId || !rewindTarget || isExecutingRewind) return
-
-    setIsExecutingRewind(true)
-    setRewindError(null)
+    const target = currentTurnPreview.target
+    setIsUndoingCurrentTurn(true)
+    setCurrentTurnError(null)
 
     try {
       if (chatState !== 'idle') {
@@ -236,15 +295,15 @@ export function MessageList({ sessionId }: MessageListProps = {}) {
       }
 
       const result = await sessionsApi.rewind(resolvedSessionId, {
-        targetUserMessageId: rewindTarget.messageId,
-        userMessageIndex: rewindTarget.userMessageIndex,
-        expectedContent: rewindTarget.content,
+        targetUserMessageId: target.messageId,
+        userMessageIndex: target.userMessageIndex,
+        expectedContent: target.expectedContent,
       })
 
       await reloadHistory(resolvedSessionId)
       queueComposerPrefill(resolvedSessionId, {
-        text: rewindTarget.content,
-        attachments: rewindTarget.attachments,
+        text: target.content,
+        attachments: target.attachments,
       })
 
       addToast({
@@ -258,8 +317,8 @@ export function MessageList({ sessionId }: MessageListProps = {}) {
             }),
       })
 
-      setRewindTarget(null)
-      setRewindPreview(null)
+      setCurrentTurnPreview(null)
+      setCurrentTurnUndoConfirmOpen(false)
     } catch (error) {
       const message =
         error instanceof ApiError
@@ -269,31 +328,30 @@ export function MessageList({ sessionId }: MessageListProps = {}) {
           : error instanceof Error
             ? error.message
             : String(error)
-      setRewindError(message)
+      setCurrentTurnError(message)
+      setCurrentTurnUndoConfirmOpen(false)
     } finally {
-      setIsExecutingRewind(false)
+      setIsUndoingCurrentTurn(false)
     }
   }, [
     addToast,
     chatState,
-    isExecutingRewind,
+    currentTurnPreview,
+    isUndoingCurrentTurn,
     queueComposerPrefill,
     reloadHistory,
     resolvedSessionId,
-    rewindTarget,
     stopGeneration,
     t,
   ])
 
-  let visibleUserMessageIndex = -1
-
   return (
     <div
       ref={scrollContainerRef}
       onScroll={updateAutoScrollState}
-      className="flex-1 overflow-y-auto px-4 py-4"
+      className={`flex-1 overflow-y-auto ${compact ? 'px-3 py-3 pb-5' : 'px-4 py-4'}`}
     >
-      <div className="mx-auto max-w-[860px]">
+      <div className={compact ? 'mx-auto max-w-full' : 'mx-auto max-w-[860px]'}>
         {renderItems.map((item) => {
           if (item.kind === 'tool_group') {
             return (
@@ -312,10 +370,6 @@ export function MessageList({ sessionId }: MessageListProps = {}) {
           }
 
           const msg = item.message
-          const rewindableUserIndex =
-            msg.type === 'user_text' && !msg.pending
-              ? ++visibleUserMessageIndex
-              : null
           return (
             <MessageBlock
               key={msg.id}
@@ -330,19 +384,6 @@ export function MessageList({ sessionId }: MessageListProps = {}) {
                     })()
                   : null
               }
-              rewindableUserIndex={rewindableUserIndex}
-              onRequestRewind={
-                !isMemberSession
-                  ? (message, userMessageIndex) => {
-                      setRewindTarget({
-                        messageId: message.id,
-                        userMessageIndex,
-                        content: message.content,
-                        attachments: message.attachments,
-                      })
-                    }
-                  : undefined
-              }
             />
           )
         })}
@@ -359,121 +400,43 @@ export function MessageList({ sessionId }: MessageListProps = {}) {
           <StreamingIndicator />
         )}
 
+        {!isLoadingCurrentTurnPreview && currentTurnPreview && resolvedSessionId && (
+          <CurrentTurnChangeCard
+            sessionId={resolvedSessionId}
+            preview={currentTurnPreview.preview}
+            workDir={currentTurnPreview.workDir}
+            error={currentTurnError}
+            isUndoing={isUndoingCurrentTurn}
+            onUndo={() => {
+              setCurrentTurnUndoConfirmOpen(true)
+            }}
+          />
+        )}
+
+        {!currentTurnPreview && currentTurnError && (
+          <div className="mx-auto mb-5 w-full max-w-[860px] rounded-[var(--radius-lg)] border border-[var(--color-error)]/25 bg-[var(--color-error-container)]/18 px-4 py-3 text-xs text-[var(--color-error)]">
+            {currentTurnError}
+          </div>
+        )}
+
         <div ref={bottomRef} />
       </div>
 
-      <Modal
-        open={Boolean(rewindTarget)}
-        onClose={closeRewindModal}
-        title={t('chat.rewindModalTitle')}
-        footer={
-          <>
-            <Button
-              variant="ghost"
-              onClick={closeRewindModal}
-              disabled={isExecutingRewind}
-            >
-              {t('common.cancel')}
-            </Button>
-            <Button
-              onClick={() => {
-                void handleConfirmRewind()
-              }}
-              loading={isExecutingRewind}
-              disabled={isLoadingPreview || Boolean(rewindError)}
-              icon={
-                !isExecutingRewind ? (
-                  <span className="material-symbols-outlined text-[16px]">undo</span>
-                ) : undefined
-              }
-            >
-              {t('chat.rewindConfirm')}
-            </Button>
-          </>
-        }
-      >
-        <div className="space-y-4">
-          <div className="rounded-[var(--radius-lg)] border border-[var(--color-border)] bg-[var(--color-surface-container-low)] px-4 py-3">
-            <div className="mb-1 text-[11px] font-semibold uppercase tracking-[0.16em] text-[var(--color-text-tertiary)]">
-              {t('chat.rewindPromptLabel')}
-            </div>
-            <div className="whitespace-pre-wrap break-words text-sm leading-relaxed text-[var(--color-text-primary)]">
-              {rewindTarget?.content || t('chat.rewindAttachmentOnly')}
-            </div>
-          </div>
-
-          {isLoadingPreview && (
-            <div className="rounded-[var(--radius-lg)] border border-[var(--color-border)] bg-[var(--color-surface-container-low)] px-4 py-3 text-sm text-[var(--color-text-secondary)]">
-              {t('chat.rewindLoading')}
-            </div>
-          )}
-
-          {!isLoadingPreview && rewindPreview && (
-            <div className="grid gap-3 md:grid-cols-[minmax(0,1fr)_220px]">
-              <div className="rounded-[var(--radius-lg)] border border-[var(--color-border)] bg-[var(--color-surface-container-low)] px-4 py-3">
-                <div className="mb-2 flex items-center gap-2 text-sm font-semibold text-[var(--color-text-primary)]">
-                  <span className="material-symbols-outlined text-[16px] text-[var(--color-brand)]">history</span>
-                  {t('chat.rewindConversationCardTitle')}
-                </div>
-                <p className="text-sm leading-relaxed text-[var(--color-text-secondary)]">
-                  {t('chat.rewindConversationCardBody', {
-                    count: rewindPreview.conversation.messagesRemoved,
-                  })}
-                </p>
-              </div>
-
-              <div className="rounded-[var(--radius-lg)] border border-[var(--color-border)] bg-[var(--color-surface-container-low)] px-4 py-3">
-                <div className="mb-2 flex items-center gap-2 text-sm font-semibold text-[var(--color-text-primary)]">
-                  <span className="material-symbols-outlined text-[16px] text-[var(--color-brand)]">code</span>
-                  {t('chat.rewindCodeCardTitle')}
-                </div>
-                {rewindPreview.code.available ? (
-                  <div className="space-y-1 text-sm text-[var(--color-text-secondary)]">
-                    <div>{t('chat.rewindCodeFiles', { count: rewindPreview.code.filesChanged.length })}</div>
-                    <div>{t('chat.rewindCodeInsertions', { count: rewindPreview.code.insertions })}</div>
-                    <div>{t('chat.rewindCodeDeletions', { count: rewindPreview.code.deletions })}</div>
-                  </div>
-                ) : (
-                  <p className="text-sm leading-relaxed text-[var(--color-text-secondary)]">
-                    {rewindPreview.code.reason || t('chat.rewindCodeUnavailable')}
-                  </p>
-                )}
-              </div>
-            </div>
-          )}
-
-          {!isLoadingPreview && rewindPreview?.code.available && rewindPreview.code.filesChanged.length > 0 && (
-            <div className="rounded-[var(--radius-lg)] border border-[var(--color-border)] bg-[var(--color-surface-container-low)] px-4 py-3">
-              <div className="mb-2 text-[11px] font-semibold uppercase tracking-[0.16em] text-[var(--color-text-tertiary)]">
-                {t('chat.rewindFilesLabel')}
-              </div>
-              <div className="flex flex-wrap gap-2">
-                {rewindPreview.code.filesChanged.slice(0, 8).map((filePath) => (
-                  <span
-                    key={filePath}
-                    className="rounded-full border border-[var(--color-border)] bg-[var(--color-surface)] px-2.5 py-1 text-[11px] text-[var(--color-text-secondary)]"
-                  >
-                    {filePath}
-                  </span>
-                ))}
-                {rewindPreview.code.filesChanged.length > 8 && (
-                  <span className="rounded-full border border-[var(--color-border)] bg-[var(--color-surface)] px-2.5 py-1 text-[11px] text-[var(--color-text-secondary)]">
-                    {t('chat.rewindFilesMore', {
-                      count: rewindPreview.code.filesChanged.length - 8,
-                    })}
-                  </span>
-                )}
-              </div>
-            </div>
-          )}
-
-          {rewindError && (
-            <div className="rounded-[var(--radius-lg)] border border-[var(--color-error)]/30 bg-[var(--color-error-container)]/22 px-4 py-3 text-sm text-[var(--color-error)]">
-              {rewindError}
-            </div>
-          )}
-        </div>
-      </Modal>
+      <ConfirmDialog
+        open={currentTurnUndoConfirmOpen}
+        onClose={() => {
+          if (!isUndoingCurrentTurn) {
+            setCurrentTurnUndoConfirmOpen(false)
+          }
+        }}
+        onConfirm={handleUndoCurrentTurn}
+        title={t('chat.turnChangesConfirmTitle')}
+        body={t('chat.turnChangesConfirmBody')}
+        confirmLabel={t('chat.turnChangesConfirmUndo')}
+        cancelLabel={t('common.cancel')}
+        confirmVariant="danger"
+        loading={isUndoingCurrentTurn}
+      />
     </div>
   )
 }
@@ -483,18 +446,11 @@ export const MessageBlock = memo(function MessageBlock({
   activeThinkingId,
   agentTaskNotifications,
   toolResult,
-  rewindableUserIndex,
-  onRequestRewind,
 }: {
   message: UIMessage
   activeThinkingId: string | null
   agentTaskNotifications: Record<string, AgentTaskNotification>
   toolResult?: { content: unknown; isError: boolean } | null
-  rewindableUserIndex?: number | null
-  onRequestRewind?: (
-    message: Extract<UIMessage, { type: 'user_text' }>,
-    userMessageIndex: number,
-  ) => void
 }) {
   const t = useTranslation()
 
@@ -504,12 +460,6 @@ export const MessageBlock = memo(function MessageBlock({
         <UserMessage
           content={message.content}
           attachments={message.attachments}
-          onRewind={
-            typeof rewindableUserIndex === 'number' && onRequestRewind
-              ? () => onRequestRewind(message, rewindableUserIndex)
-              : undefined
-          }
-          rewindLabel={t('chat.rewindAction')}
         />
       )
     case 'assistant_text':

desktop/src/components/chat/UserMessage.tsx

@@ -5,11 +5,9 @@ import { MessageActionBar } from './MessageActionBar'
 type Props = {
   content: string
   attachments?: UIAttachment[]
-  onRewind?: () => void
-  rewindLabel?: string
 }
 
-export function UserMessage({ content, attachments, onRewind, rewindLabel }: Props) {
+export function UserMessage({ content, attachments }: Props) {
   const hasText = content.trim().length > 0
 
   return (
@@ -35,8 +33,6 @@ export function UserMessage({ content, attachments, onRewind, rewindLabel }: Pro
           <MessageActionBar
             copyText={content}
             copyLabel="Copy prompt"
-            onRewind={onRewind}
-            rewindLabel={rewindLabel}
             align="end"
           />
         )}

desktop/src/components/chat/chatBlocks.test.tsx

@@ -4,10 +4,12 @@ import { ThinkingBlock } from './ThinkingBlock'
 import { ToolCallBlock } from './ToolCallBlock'
 import { PermissionDialog } from './PermissionDialog'
 import { useChatStore } from '../../stores/chatStore'
+import { useSettingsStore } from '../../stores/settingsStore'
 import { useTabStore } from '../../stores/tabStore'
 
 describe('chat blocks', () => {
   beforeEach(() => {
+    useSettingsStore.setState({ locale: 'en' })
     useTabStore.setState({ activeTabId: 'active-tab', tabs: [{ sessionId: 'active-tab', title: 'Test', type: 'session' as const, status: 'idle' }] })
     useChatStore.setState({ sessions: {} })
   })

desktop/src/components/controls/ModelSelector.tsx

@@ -21,6 +21,7 @@ type Props = {
   onChange?: (modelId: string) => void
   runtimeKey?: string
   disabled?: boolean
+  compact?: boolean
 }
 
 function officialChoices(availableModels: ModelInfo[], isDefault: boolean, officialName: string): ProviderChoice {
@@ -105,6 +106,7 @@ export function ModelSelector({
   onChange,
   runtimeKey,
   disabled = false,
+  compact = false,
 }: Props = {}) {
   const t = useTranslation()
   const {
@@ -229,13 +231,15 @@ export function ModelSelector({
       <button
         onClick={() => !disabled && setOpen(!open)}
         disabled={disabled}
-        className="flex max-w-[280px] items-center gap-2 rounded-full bg-[var(--color-surface-container-low)] px-3 py-1.5 text-xs font-medium text-[var(--color-text-secondary)] transition-colors hover:bg-[var(--color-surface-hover)] disabled:cursor-not-allowed disabled:opacity-50"
+        className={`flex items-center gap-2 rounded-full bg-[var(--color-surface-container-low)] text-xs font-medium text-[var(--color-text-secondary)] transition-colors hover:bg-[var(--color-surface-hover)] disabled:cursor-not-allowed disabled:opacity-50 ${
+          compact ? 'max-w-[152px] px-2.5 py-1.5' : 'max-w-[280px] px-3 py-1.5'
+        }`}
       >
         <div className="flex min-w-0 flex-1 items-center gap-2">
-          <span className="min-w-0 flex-1 truncate text-sm font-semibold text-[var(--color-text-primary)]">
+          <span className={`${compact ? 'text-xs' : 'text-sm'} min-w-0 flex-1 truncate font-semibold text-[var(--color-text-primary)]`}>
             {buttonModelLabel}
           </span>
-          {buttonProviderLabel && (
+          {!compact && buttonProviderLabel && (
             <span className="max-w-[108px] flex-shrink-0 truncate text-[11px] text-[var(--color-text-tertiary)]">
               {buttonProviderLabel}
             </span>

desktop/src/components/controls/PermissionModeSelector.tsx

@@ -18,13 +18,14 @@ const MODE_ICONS: Record<PermissionMode, string> = {
 
 type Props = {
   workDir?: string
+  compact?: boolean
   /** Controlled mode: override current value */
   value?: PermissionMode
   /** Controlled mode: called on change instead of updating global store */
   onChange?: (mode: PermissionMode) => void
 }
 
-export function PermissionModeSelector({ workDir: workDirProp, value, onChange }: Props = {}) {
+export function PermissionModeSelector({ workDir: workDirProp, compact = false, value, onChange }: Props = {}) {
   const t = useTranslation()
   const { permissionMode: storeMode, setPermissionMode } = useSettingsStore()
   const setSessionPermissionMode = useChatStore((s) => s.setSessionPermissionMode)
@@ -104,11 +105,20 @@ export function PermissionModeSelector({ workDir: workDirProp, value, onChange }
     <div ref={ref} className="relative">
       <button
         onClick={() => setOpen(!open)}
-        className="flex items-center gap-1.5 px-2.5 py-1.5 bg-[var(--color-surface-container-low)] hover:bg-[var(--color-surface-hover)] rounded-full text-xs font-medium text-[var(--color-text-secondary)] transition-colors"
+        title={compact ? MODE_LABELS[currentMode] : undefined}
+        className={`flex items-center bg-[var(--color-surface-container-low)] font-medium text-[var(--color-text-secondary)] transition-colors hover:bg-[var(--color-surface-hover)] ${
+          compact
+            ? 'h-8 w-8 justify-center rounded-full p-0'
+            : 'gap-1.5 rounded-full px-2.5 py-1.5 text-xs'
+        }`}
       >
         <span className="material-symbols-outlined text-[14px]">{MODE_ICONS[currentMode]}</span>
-        <span>{MODE_LABELS[currentMode]}</span>
-        <span className="material-symbols-outlined text-[12px]">expand_more</span>
+        {!compact && (
+          <>
+            <span>{MODE_LABELS[currentMode]}</span>
+            <span className="material-symbols-outlined text-[12px]">expand_more</span>
+          </>
+        )}
       </button>
 
       {open && (

desktop/src/components/layout/Sidebar.test.tsx

@@ -11,7 +11,6 @@ vi.mock('../../i18n', () => ({
     const translations: Record<string, string> = {
       'sidebar.newSession': 'New Session',
       'sidebar.scheduled': 'Scheduled',
-      'sidebar.terminal': 'Terminal',
       'sidebar.settings': 'Settings',
       'sidebar.searchPlaceholder': 'Search sessions',
       'sidebar.noSessions': 'No sessions',
@@ -105,26 +104,6 @@ describe('Sidebar', () => {
     expect(screen.getByRole('complementary')).not.toHaveAttribute('data-tauri-drag-region')
   })
 
-  it('opens each terminal click as a first-class app tab', () => {
-    render(<Sidebar />)
-
-    fireEvent.click(screen.getByRole('button', { name: 'Terminal' }))
-    fireEvent.click(screen.getByRole('button', { name: 'Terminal' }))
-
-    const terminalTabs = useTabStore.getState().tabs.filter((tab) => tab.type === 'terminal')
-    expect(terminalTabs).toHaveLength(2)
-    expect(terminalTabs.map((tab) => tab.title)).toEqual(['Terminal 1', 'Terminal 2'])
-    expect(useTabStore.getState().activeTabId).toBe(terminalTabs[1]!.sessionId)
-
-    useTabStore.getState().closeTab(terminalTabs[0]!.sessionId)
-    useTabStore.getState().openTerminalTab()
-
-    expect(useTabStore.getState().tabs.filter((tab) => tab.type === 'terminal').map((tab) => tab.title)).toEqual([
-      'Terminal 2',
-      'Terminal 3',
-    ])
-  })
-
   it('shows a toast when session creation fails', async () => {
     createSession.mockRejectedValue(new Error('boom'))
 

desktop/src/components/layout/Sidebar.tsx

@@ -26,7 +26,6 @@ export function Sidebar() {
   const sidebarOpen = useUIStore((s) => s.sidebarOpen)
   const toggleSidebar = useUIStore((s) => s.toggleSidebar)
   const activeTabId = useTabStore((s) => s.activeTabId)
-  const activeTabType = useTabStore((s) => s.tabs.find((tab) => tab.sessionId === s.activeTabId)?.type)
   const closeTab = useTabStore((s) => s.closeTab)
   const disconnectSession = useChatStore((s) => s.disconnectSession)
   const [searchQuery, setSearchQuery] = useState('')
@@ -203,15 +202,6 @@ export function Sidebar() {
         >
           {t('sidebar.scheduled')}
         </NavItem>
-        <NavItem
-          active={activeTabType === 'terminal'}
-          collapsed={!sidebarOpen}
-          label={t('sidebar.terminal')}
-          onClick={() => useTabStore.getState().openTerminalTab()}
-          icon={<span className="material-symbols-outlined text-[18px]">terminal</span>}
-        >
-          {t('sidebar.terminal')}
-        </NavItem>
       </div>
 
       {sidebarOpen ? (

desktop/src/components/layout/TabBar.test.tsx

@@ -23,6 +23,9 @@ vi.mock('../../i18n', () => ({
       'tabs.closeConfirmMessage': 'Still running',
       'tabs.closeConfirmKeep': 'Keep Running',
       'tabs.closeConfirmStop': 'Stop & Close',
+      'tabs.openTerminal': 'Open Terminal',
+      'tabs.showWorkspace': 'Show Workspace',
+      'tabs.hideWorkspace': 'Hide Workspace',
       'common.cancel': 'Cancel',
     }
 
@@ -64,11 +67,13 @@ describe('TabBar', () => {
   afterEach(async () => {
     const { useTabStore } = await import('../../stores/tabStore')
     const { useChatStore } = await import('../../stores/chatStore')
+    const { useWorkspacePanelStore } = await import('../../stores/workspacePanelStore')
 
     useTabStore.setState({ tabs: [], activeTabId: null })
     useChatStore.setState({
       sessions: {},
     } as Partial<ReturnType<typeof useChatStore.getState>>)
+    useWorkspacePanelStore.setState(useWorkspacePanelStore.getInitialState(), true)
 
     delete (window as typeof window & { __TAURI__?: unknown }).__TAURI__
   })
@@ -356,11 +361,122 @@ describe('TabBar', () => {
       render(<TabBar />)
     })
 
-    expect(screen.getByText('terminal')).toBeInTheDocument()
+    expect(screen.getByLabelText('Open Terminal')).toBeInTheDocument()
 
     fireEvent.click(screen.getByLabelText('Close Terminal 1'))
 
     expect(disconnectSession).not.toHaveBeenCalled()
     expect(useTabStore.getState().tabs).toEqual([])
   })
+
+  it('opens a terminal tab from the toolbar', async () => {
+    const { TabBar } = await import('./TabBar')
+    const { useTabStore } = await import('../../stores/tabStore')
+    const { useChatStore } = await import('../../stores/chatStore')
+
+    useTabStore.setState({
+      tabs: [
+        { sessionId: 'tab-1', title: 'First Session', type: 'session', status: 'idle' },
+      ],
+      activeTabId: 'tab-1',
+    })
+    useChatStore.setState({
+      sessions: {},
+      disconnectSession: vi.fn(),
+    } as Partial<ReturnType<typeof useChatStore.getState>>)
+
+    await act(async () => {
+      render(<TabBar />)
+    })
+
+    fireEvent.click(screen.getByRole('button', { name: 'Open Terminal' }))
+
+    const terminalTabs = useTabStore.getState().tabs.filter((tab) => tab.type === 'terminal')
+    expect(terminalTabs).toHaveLength(1)
+    expect(useTabStore.getState().activeTabId).toBe(terminalTabs[0]?.sessionId)
+  })
+
+  it('toggles the workspace panel for the active session from the toolbar', async () => {
+    const { TabBar } = await import('./TabBar')
+    const { useTabStore } = await import('../../stores/tabStore')
+    const { useChatStore } = await import('../../stores/chatStore')
+    const { useWorkspacePanelStore } = await import('../../stores/workspacePanelStore')
+
+    useTabStore.setState({
+      tabs: [
+        { sessionId: 'tab-1', title: 'First Session', type: 'session', status: 'idle' },
+      ],
+      activeTabId: 'tab-1',
+    })
+    useChatStore.setState({
+      sessions: {},
+      disconnectSession: vi.fn(),
+    } as Partial<ReturnType<typeof useChatStore.getState>>)
+
+    await act(async () => {
+      render(<TabBar />)
+    })
+
+    fireEvent.click(screen.getByRole('button', { name: 'Show Workspace' }))
+    expect(useWorkspacePanelStore.getState().isPanelOpen('tab-1')).toBe(true)
+
+    fireEvent.click(screen.getByRole('button', { name: 'Hide Workspace' }))
+    expect(useWorkspacePanelStore.getState().isPanelOpen('tab-1')).toBe(false)
+  })
+
+  it('hides the workspace toolbar button for non-session tabs', async () => {
+    const { TabBar } = await import('./TabBar')
+    const { useTabStore } = await import('../../stores/tabStore')
+    const { useChatStore } = await import('../../stores/chatStore')
+
+    useTabStore.setState({
+      tabs: [
+        { sessionId: '__terminal__1', title: 'Terminal 1', type: 'terminal', status: 'idle' },
+        { sessionId: '__settings__', title: 'Settings', type: 'settings', status: 'idle' },
+      ],
+      activeTabId: '__terminal__1',
+    })
+    useChatStore.setState({
+      sessions: {},
+      disconnectSession: vi.fn(),
+    } as Partial<ReturnType<typeof useChatStore.getState>>)
+
+    const { rerender } = render(<TabBar />)
+
+    expect(screen.queryByRole('button', { name: 'Show Workspace' })).not.toBeInTheDocument()
+
+    await act(async () => {
+      useTabStore.getState().setActiveTab('__settings__')
+    })
+    rerender(<TabBar />)
+
+    expect(screen.queryByRole('button', { name: 'Show Workspace' })).not.toBeInTheDocument()
+  })
+
+  it('clears workspace panel state when closing a session tab', async () => {
+    const { TabBar } = await import('./TabBar')
+    const { useTabStore } = await import('../../stores/tabStore')
+    const { useChatStore } = await import('../../stores/chatStore')
+    const { useWorkspacePanelStore } = await import('../../stores/workspacePanelStore')
+
+    useTabStore.setState({
+      tabs: [
+        { sessionId: 'tab-1', title: 'First Session', type: 'session', status: 'idle' },
+      ],
+      activeTabId: 'tab-1',
+    })
+    useChatStore.setState({
+      sessions: {},
+      disconnectSession: vi.fn(),
+    } as Partial<ReturnType<typeof useChatStore.getState>>)
+    useWorkspacePanelStore.getState().openPanel('tab-1')
+
+    await act(async () => {
+      render(<TabBar />)
+    })
+
+    fireEvent.click(screen.getByLabelText('Close First Session'))
+
+    expect(useWorkspacePanelStore.getState().panelBySession['tab-1']).toBeUndefined()
+  })
 })

desktop/src/components/layout/TabBar.tsx

@@ -1,8 +1,10 @@
 import { forwardRef, useRef, useState, useEffect, useCallback } from 'react'
 import { useTabStore, type Tab } from '../../stores/tabStore'
 import { useChatStore } from '../../stores/chatStore'
+import { useWorkspacePanelStore } from '../../stores/workspacePanelStore'
 import { useTranslation } from '../../i18n'
 import { WindowControls, showWindowControls } from './WindowControls'
+import { Folder, FolderOpen, SquareTerminal } from 'lucide-react'
 
 const TAB_WIDTH = 180
 const DRAG_START_THRESHOLD = 4
@@ -14,6 +16,11 @@ export function TabBar() {
   const setActiveTab = useTabStore((s) => s.setActiveTab)
   const closeTab = useTabStore((s) => s.closeTab)
   const disconnectSession = useChatStore((s) => s.disconnectSession)
+  const activeTab = tabs.find((tab) => tab.sessionId === activeTabId) ?? null
+  const isActiveSessionTab = activeTab?.type === 'session'
+  const isWorkspacePanelOpen = useWorkspacePanelStore((state) =>
+    activeTabId && isActiveSessionTab ? state.isPanelOpen(activeTabId) : false,
+  )
 
   const moveTab = useTabStore((s) => s.moveTab)
   const scrollRef = useRef<HTMLDivElement>(null)
@@ -74,12 +81,19 @@ export function TabBar() {
     el.scrollBy({ left: direction === 'left' ? -TAB_WIDTH : TAB_WIDTH, behavior: 'smooth' })
   }
 
+  const closeTabWithCleanup = useCallback((tab: Tab) => {
+    if (tab.type === 'session') {
+      useWorkspacePanelStore.getState().clearSession(tab.sessionId)
+    }
+    closeTab(tab.sessionId)
+  }, [closeTab])
+
   const handleClose = (sessionId: string) => {
     // Special tabs can always be closed directly
     const tab = tabs.find((t) => t.sessionId === sessionId)
     if (!tab) return
     if (tab.type !== 'session') {
-      closeTab(sessionId)
+      closeTabWithCleanup(tab)
       return
     }
 
@@ -92,7 +106,7 @@ export function TabBar() {
     }
 
     disconnectSession(sessionId)
-    closeTab(sessionId)
+    closeTabWithCleanup(tab)
   }
 
   const handleContextMenu = (e: React.MouseEvent, sessionId: string) => {
@@ -105,7 +119,7 @@ export function TabBar() {
     const otherTabs = tabs.filter((t) => t.sessionId !== sessionId)
     for (const tab of otherTabs) {
       if (tab.type === 'session') disconnectSession(tab.sessionId)
-      closeTab(tab.sessionId)
+      closeTabWithCleanup(tab)
     }
   }
 
@@ -115,7 +129,7 @@ export function TabBar() {
     const leftTabs = tabs.slice(0, idx)
     for (const tab of leftTabs) {
       if (tab.type === 'session') disconnectSession(tab.sessionId)
-      closeTab(tab.sessionId)
+      closeTabWithCleanup(tab)
     }
   }
 
@@ -125,7 +139,7 @@ export function TabBar() {
     const rightTabs = tabs.slice(idx + 1)
     for (const tab of rightTabs) {
       if (tab.type === 'session') disconnectSession(tab.sessionId)
-      closeTab(tab.sessionId)
+      closeTabWithCleanup(tab)
     }
   }
 
@@ -133,7 +147,7 @@ export function TabBar() {
     setContextMenu(null)
     for (const tab of tabs) {
       if (tab.type === 'session') disconnectSession(tab.sessionId)
-      closeTab(tab.sessionId)
+      closeTabWithCleanup(tab)
     }
   }
 
@@ -265,6 +279,22 @@ export function TabBar() {
         ))}
       </div>
 
+      <div className="flex shrink-0 items-center gap-1 border-l border-[var(--color-border)]/70 px-2">
+        <ToolbarIconButton
+          icon={<SquareTerminal size={17} strokeWidth={1.9} />}
+          label={t('tabs.openTerminal')}
+          onClick={() => useTabStore.getState().openTerminalTab()}
+        />
+        {isActiveSessionTab && activeTabId && (
+          <ToolbarIconButton
+            icon={isWorkspacePanelOpen ? <FolderOpen size={18} strokeWidth={1.9} /> : <Folder size={18} strokeWidth={1.9} />}
+            label={t(isWorkspacePanelOpen ? 'tabs.hideWorkspace' : 'tabs.showWorkspace')}
+            onClick={() => useWorkspacePanelStore.getState().togglePanel(activeTabId)}
+            active={isWorkspacePanelOpen}
+          />
+        )}
+      </div>
+
       {isTauri && (
         <div
           data-testid="tab-bar-drag-gutter"
@@ -331,7 +361,11 @@ export function TabBar() {
                 {t('common.cancel')}
               </button>
               <button
-                onClick={() => { closeTab(closingTabId); setClosingTabId(null) }}
+                onClick={() => {
+                  const tab = tabs.find((item) => item.sessionId === closingTabId)
+                  if (tab) closeTabWithCleanup(tab)
+                  setClosingTabId(null)
+                }}
                 className="px-3 py-1.5 text-xs rounded-lg border border-[var(--color-border)] text-[var(--color-text-secondary)] hover:bg-[var(--color-surface-hover)]"
               >
                 {t('tabs.closeConfirmKeep')}
@@ -340,7 +374,8 @@ export function TabBar() {
                 onClick={() => {
                   useChatStore.getState().stopGeneration(closingTabId)
                   disconnectSession(closingTabId)
-                  closeTab(closingTabId)
+                  const tab = tabs.find((item) => item.sessionId === closingTabId)
+                  if (tab) closeTabWithCleanup(tab)
                   setClosingTabId(null)
                 }}
                 className="px-3 py-1.5 text-xs rounded-lg bg-[var(--color-brand)] text-white hover:opacity-90"
@@ -423,3 +458,32 @@ const TabItem = forwardRef<HTMLDivElement, {
   )
 })
 TabItem.displayName = 'TabItem'
+
+function ToolbarIconButton({
+  icon,
+  label,
+  onClick,
+  active = false,
+}: {
+  icon: React.ReactNode
+  label: string
+  onClick: () => void
+  active?: boolean
+}) {
+  return (
+    <button
+      type="button"
+      aria-label={label}
+      title={label}
+      onClick={onClick}
+      data-active={active ? 'true' : 'false'}
+      className={`inline-flex h-8 w-8 items-center justify-center rounded-[10px] transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-border-focus)] ${
+        active
+          ? 'bg-[var(--color-surface-hover)] text-[var(--color-text-primary)]'
+          : 'text-[var(--color-text-tertiary)] hover:bg-[var(--color-surface-hover)] hover:text-[var(--color-text-primary)]'
+      }`}
+    >
+      {icon}
+    </button>
+  )
+}

desktop/src/components/shared/ProjectContextChip.tsx

@@ -2,21 +2,26 @@ type Props = {
   workDir?: string | null
   repoName?: string | null
   branch?: string | null
+  compact?: boolean
 }
 
-export function ProjectContextChip({ workDir, repoName, branch }: Props) {
+export function ProjectContextChip({ workDir, repoName, branch, compact = false }: Props) {
   const label = branch ? (repoName || workDir?.split('/').pop() || '') : (workDir?.split('/').pop() || repoName || '')
 
   if (!label) return null
 
   return (
-    <div className="inline-flex max-w-full items-center gap-2 rounded-full border border-[var(--color-border)] bg-[var(--color-surface-container-lowest)] px-4 py-2 text-sm text-[var(--color-text-secondary)]">
+    <div
+      className={`inline-flex max-w-full items-center rounded-full border border-[var(--color-border)] bg-[var(--color-surface-container-lowest)] text-[var(--color-text-secondary)] ${
+        compact ? 'gap-1.5 px-3 py-1.5 text-xs' : 'gap-2 px-4 py-2 text-sm'
+      }`}
+    >
       {branch ? (
-        <svg width="18" height="18" viewBox="0 0 16 16" fill="currentColor" className="shrink-0 text-[var(--color-text-secondary)]">
+        <svg width={compact ? 15 : 18} height={compact ? 15 : 18} viewBox="0 0 16 16" fill="currentColor" className="shrink-0 text-[var(--color-text-secondary)]">
           <path d="M8 0C3.58 0 0 3.58 0 8c0 3.54 2.29 6.53 5.47 7.59.4.07.55-.17.55-.38 0-.19-.01-.82-.01-1.49-2.01.37-2.53-.49-2.69-.94-.09-.23-.48-.94-.82-1.13-.28-.15-.68-.52-.01-.53.63-.01 1.08.58 1.23.82.72 1.21 1.87.87 2.33.66.07-.52.28-.87.51-1.07-1.78-.2-3.64-.89-3.64-3.95 0-.87.31-1.59.82-2.15-.08-.2-.36-1.02.08-2.12 0 0 .67-.21 2.2.82.64-.18 1.32-.27 2-.27.68 0 1.36.09 2 .27 1.53-1.04 2.2-.82 2.2-.82.44 1.1.16 1.92.08 2.12.51.56.82 1.27.82 2.15 0 3.07-1.87 3.75-3.65 3.95.29.25.54.73.54 1.48 0 1.07-.01 1.93-.01 2.2 0 .21.15.46.55.38A8.013 8.013 0 0016 8c0-4.42-3.58-8-8-8z" />
         </svg>
       ) : (
-        <span className="material-symbols-outlined text-[18px] text-[var(--color-text-secondary)]">folder</span>
+        <span className={`material-symbols-outlined text-[var(--color-text-secondary)] ${compact ? 'text-[15px]' : 'text-[18px]'}`}>folder</span>
       )}
       <span className="truncate font-medium text-[var(--color-text-primary)]">{label}</span>
       {branch ? (

desktop/src/components/shared/UpdateChecker.test.tsx

@@ -3,10 +3,12 @@ import { render, screen } from '@testing-library/react'
 import '@testing-library/jest-dom'
 
 import { UpdateChecker } from './UpdateChecker'
+import { useSettingsStore } from '../../stores/settingsStore'
 import { useUpdateStore } from '../../stores/updateStore'
 
 describe('UpdateChecker', () => {
   beforeEach(() => {
+    useSettingsStore.setState({ locale: 'en' })
     Object.defineProperty(window, '__TAURI__', {
       value: {},
       configurable: true,

desktop/src/components/workspace/WorkspaceCodeSurface.tsx

@@ -0,0 +1,174 @@
+import { Highlight, type PrismTheme } from 'prism-react-renderer'
+import { useTranslation } from '../../i18n'
+
+export const WORKSPACE_PREVIEW_LINE_LIMIT = 420
+
+export const workspacePrismTheme: PrismTheme = {
+  plain: {
+    color: 'var(--color-code-fg)',
+    backgroundColor: 'transparent',
+  },
+  styles: [
+    { types: ['comment', 'prolog', 'doctype', 'cdata'], style: { color: 'var(--color-code-comment)', fontStyle: 'italic' } },
+    { types: ['string', 'attr-value', 'template-string'], style: { color: 'var(--color-code-string)' } },
+    { types: ['keyword', 'selector', 'important', 'atrule'], style: { color: 'var(--color-code-keyword)' } },
+    { types: ['function'], style: { color: 'var(--color-code-function)' } },
+    { types: ['tag'], style: { color: 'var(--color-code-keyword)' } },
+    { types: ['number', 'boolean'], style: { color: 'var(--color-code-number)' } },
+    { types: ['operator'], style: { color: 'var(--color-code-fg)' } },
+    { types: ['punctuation'], style: { color: 'var(--color-code-punctuation)' } },
+    { types: ['variable', 'parameter'], style: { color: 'var(--color-code-fg)' } },
+    { types: ['property', 'attr-name'], style: { color: 'var(--color-code-property)' } },
+    { types: ['builtin', 'class-name', 'constant', 'symbol'], style: { color: 'var(--color-code-type)' } },
+    { types: ['inserted'], style: { color: 'var(--color-code-inserted)' } },
+    { types: ['deleted'], style: { color: 'var(--color-code-deleted)' } },
+  ],
+}
+
+export function getFileExtension(name: string) {
+  const cleanName = name.split('/').pop() ?? name
+  const lastDot = cleanName.lastIndexOf('.')
+  if (lastDot <= 0 || lastDot === cleanName.length - 1) return ''
+  return cleanName.slice(lastDot + 1).toLowerCase()
+}
+
+export function normalizePrismLanguage(language: string) {
+  const lower = language.toLowerCase()
+  const map: Record<string, string> = {
+    text: 'text',
+    typescript: 'typescript',
+    ts: 'typescript',
+    tsx: 'tsx',
+    javascript: 'javascript',
+    js: 'javascript',
+    jsx: 'jsx',
+    markdown: 'markdown',
+    md: 'markdown',
+    html: 'markup',
+    xml: 'markup',
+    shell: 'bash',
+    sh: 'bash',
+    zsh: 'bash',
+    diff: 'diff',
+  }
+  return map[lower] ?? lower
+}
+
+export function getLanguageFromPath(path: string) {
+  return normalizePrismLanguage(getFileExtension(path) || 'text')
+}
+
+export function InlineHighlightedCode({
+  value,
+  language,
+}: {
+  value: string
+  language: string
+}) {
+  return (
+    <Highlight
+      theme={workspacePrismTheme}
+      code={value}
+      language={normalizePrismLanguage(language)}
+    >
+      {({ tokens, getTokenProps }) => (
+        <>
+          {(tokens[0] ?? []).map((token, tokenIndex) => {
+            const { key: tokenKey, ...tokenProps } = getTokenProps({ token, key: tokenIndex })
+            return <span key={String(tokenKey)} {...tokenProps} />
+          })}
+        </>
+      )}
+    </Highlight>
+  )
+}
+
+export function WorkspaceDiffSurface({
+  value,
+  path,
+  className = 'min-h-0 flex-1 overflow-auto bg-[var(--color-code-bg)]',
+  lineLimit = WORKSPACE_PREVIEW_LINE_LIMIT,
+}: {
+  value: string
+  path: string
+  className?: string
+  lineLimit?: number
+}) {
+  const t = useTranslation()
+  const lines = value.split('\n')
+  const visibleLines = lines.slice(0, lineLimit)
+  const hiddenLineCount = Math.max(0, lines.length - visibleLines.length)
+  const language = getLanguageFromPath(path)
+
+  return (
+    <div className={className}>
+      <div className="relative min-w-max py-2">
+        <pre
+          data-workspace-code=""
+          data-testid="workspace-code"
+          className="m-0 font-[var(--font-mono)] text-[12px] leading-[1.55] text-[var(--color-code-fg)]"
+        >
+          {visibleLines.map((line, index) => {
+            const isFileHeader = line.startsWith('diff --') || line.startsWith('--- ') || line.startsWith('+++ ')
+            const isHunk = line.startsWith('@@')
+            const isAdded = line.startsWith('+') && !line.startsWith('+++')
+            const isRemoved = line.startsWith('-') && !line.startsWith('---')
+            const isCodeLine = isAdded || isRemoved || line.startsWith(' ')
+            const code = isCodeLine ? line.slice(1) : line
+            const prefix = isCodeLine ? line[0] : ' '
+
+            return (
+              <div
+                key={`${index}:${line}`}
+                className={`grid grid-cols-[48px_18px_minmax(0,1fr)] gap-2 px-3 ${
+                  isAdded
+                    ? 'bg-[var(--color-diff-added-bg)]'
+                    : isRemoved
+                      ? 'bg-[var(--color-diff-removed-bg)]'
+                      : isHunk
+                        ? 'bg-[var(--color-diff-highlight-bg)]'
+                        : 'hover:bg-[var(--color-surface-hover)]'
+                }`}
+              >
+                <span className="select-none text-right text-[11px] text-[var(--color-text-tertiary)]">
+                  {index + 1}
+                </span>
+                <span
+                  className={`select-none text-center ${
+                    isAdded
+                      ? 'text-[var(--color-diff-added-text)]'
+                      : isRemoved
+                        ? 'text-[var(--color-diff-removed-text)]'
+                        : 'text-[var(--color-text-tertiary)]'
+                  }`}
+                >
+                  {prefix}
+                </span>
+                <span
+                  className={`whitespace-pre pr-6 ${
+                    isFileHeader
+                      ? 'font-semibold text-[var(--color-text-secondary)]'
+                      : isHunk
+                        ? 'font-semibold text-[var(--color-warning)]'
+                        : ''
+                  }`}
+                >
+                  {isCodeLine ? (
+                    code ? <InlineHighlightedCode value={code} language={language} /> : ' '
+                  ) : (
+                    code || ' '
+                  )}
+                </span>
+              </div>
+            )
+          })}
+        </pre>
+        {hiddenLineCount > 0 && (
+          <div className="sticky bottom-0 border-t border-[var(--color-border)] bg-[var(--color-surface-glass)] px-3 py-2 text-xs text-[var(--color-text-tertiary)] backdrop-blur">
+            {t('workspace.previewLineLimit', { count: lineLimit })}
+          </div>
+        )}
+      </div>
+    </div>
+  )
+}

desktop/src/i18n/locales/en.ts

@@ -41,6 +41,41 @@ export const en = {
   'titlebar.terminal': 'Terminal',
   'titlebar.history': 'History',
 
+  // ─── Workspace Panel ───────────────────────────────
+  'workspace.changedFiles': 'Changed files',
+  'workspace.allFiles': 'All files',
+  'workspace.viewTabs': 'Workspace views',
+  'workspace.previewTabs': 'Preview tabs',
+  'workspace.filterPlaceholder': 'Filter files...',
+  'workspace.clearFilter': 'Clear file filter',
+  'workspace.refresh': 'Refresh workspace',
+  'workspace.closePanel': 'Close workspace panel',
+  'workspace.resizePanel': 'Resize workspace panel',
+  'workspace.closeTab': 'Close tab',
+  'workspace.preview': 'Preview',
+  'workspace.previewEmpty': 'Select a file to preview.',
+  'workspace.notGitRepo': 'Not a git repository.',
+  'workspace.missingWorkdir': 'Working directory is missing.',
+  'workspace.loadError': 'Failed to load workspace data.',
+  'workspace.noChanges': 'No changes',
+  'workspace.noFiles': 'No files',
+  'workspace.noMatchingFiles': 'No matching files',
+  'workspace.previewKind.diff': 'Diff',
+  'workspace.previewKind.file': 'File',
+  'workspace.previewState.loading': 'Loading preview...',
+  'workspace.previewState.binary': 'Binary file preview is unavailable.',
+  'workspace.previewState.tooLarge': 'File is too large to preview.',
+  'workspace.previewState.missing': 'File not found.',
+  'workspace.imagePreviewUnavailable': 'Image preview is unavailable.',
+  'workspace.previewLineLimit': 'Showing first {count} lines. Open in your editor for the full file.',
+  'workspace.addToChat': 'Add to chat',
+  'workspace.copyPath': 'Copy path',
+  'workspace.localComment': 'Local comment',
+  'workspace.commentLine': 'Comment line {line}',
+  'workspace.commentLineTarget': 'Line {line}',
+  'workspace.commentPlaceholder': 'Describe what should change here...',
+  'workspace.addCommentToChat': 'Add comment',
+
   // ─── Status Bar ──────────────────────────────────────
   'status.connected': 'Connected',
   'status.connecting': 'Connecting...',
@@ -520,6 +555,7 @@ export const en = {
   'chat.placeholder': 'Ask Claude to edit, debug or explain...',
   'chat.placeholderMissing': 'This session points to a missing workspace. Create a new session or pick another project.',
   'chat.addFiles': 'Add files or photos',
+  'chat.workspaceReferencesOnly': 'Added {count} workspace references',
   'chat.slashCommands': 'Slash commands',
   'slash.mcp.title': 'Available MCP tools',
   'slash.mcp.subtitle': 'Global and current-project MCP servers available in this chat context.',
@@ -610,23 +646,21 @@ export const en = {
   'chat.select': 'select',
   'chat.dismiss': 'dismiss',
   'chat.stopTitle': 'Stop generation (Cmd+.)',
-  'chat.rewindAction': 'Rewind to here',
-  'chat.rewindModalTitle': 'Rewind Conversation',
-  'chat.rewindConfirm': 'Rewind here',
-  'chat.rewindPromptLabel': 'Selected prompt',
-  'chat.rewindAttachmentOnly': 'This message only contains attachments.',
-  'chat.rewindLoading': 'Inspecting file checkpoints for this turn...',
-  'chat.rewindConversationCardTitle': 'Conversation rollback',
-  'chat.rewindConversationCardBody': 'Remove this prompt and the {count} active messages that follow it, then reopen the composer at that point.',
-  'chat.rewindCodeCardTitle': 'Code rollback',
-  'chat.rewindCodeFiles': '{count} files will be restored',
-  'chat.rewindCodeInsertions': '{count} insertions will be removed',
-  'chat.rewindCodeDeletions': '{count} deletions will be restored',
-  'chat.rewindCodeUnavailable': 'No file checkpoint is available for this prompt. The conversation can still be rewound.',
-  'chat.rewindFilesLabel': 'Affected files',
-  'chat.rewindFilesMore': '+{count} more',
   'chat.rewindSuccessWithCode': 'Rewound {count} messages and restored tracked files.',
   'chat.rewindSuccessConversationOnly': 'Rewound {count} messages. No file checkpoint was available for this turn.',
+  'chat.turnChangesCardLabel': 'Current turn changed files',
+  'chat.turnChangesTitle': '{count} files changed',
+  'chat.turnChangesSubtitle': 'Current turn checkpoint',
+  'chat.turnChangesUndo': 'Undo',
+  'chat.turnChangesUndoing': 'Undoing...',
+  'chat.turnChangesUndoAria': 'Undo current turn changes',
+  'chat.turnChangesConfirmTitle': 'Undo current turn?',
+  'chat.turnChangesConfirmBody': 'This will rewind the latest assistant response and restore tracked files for this turn.',
+  'chat.turnChangesConfirmUndo': 'Undo current turn',
+  'chat.turnChangesShowDiffAria': 'Show diff for {path}',
+  'chat.turnChangesHideDiffAria': 'Hide diff for {path}',
+  'chat.turnChangesDiffLoading': 'Loading diff...',
+  'chat.turnChangesDiffUnavailable': 'Diff unavailable.',
 
   // ─── Streaming Indicator ──────────────────────────────────────
   'streaming.thinking': 'Thinking',
@@ -983,6 +1017,9 @@ export const en = {
   'tabs.closeConfirmMessage': 'This session is still running. What would you like to do?',
   'tabs.closeConfirmKeep': 'Keep Running',
   'tabs.closeConfirmStop': 'Stop & Close',
+  'tabs.openTerminal': 'Open Terminal',
+  'tabs.showWorkspace': 'Show Workspace',
+  'tabs.hideWorkspace': 'Hide Workspace',
 } as const
 
 export type TranslationKey = keyof typeof en

desktop/src/i18n/locales/zh.ts

@@ -43,6 +43,41 @@ export const zh: Record<TranslationKey, string> = {
   'titlebar.terminal': '终端',
   'titlebar.history': '历史',
 
+  // ─── Workspace Panel ───────────────────────────────
+  'workspace.changedFiles': '已更改文件',
+  'workspace.allFiles': '所有文件',
+  'workspace.viewTabs': '工作区视图',
+  'workspace.previewTabs': '预览标签',
+  'workspace.filterPlaceholder': '筛选文件...',
+  'workspace.clearFilter': '清除文件筛选',
+  'workspace.refresh': '刷新工作区',
+  'workspace.closePanel': '关闭工作区面板',
+  'workspace.resizePanel': '调整工作区宽度',
+  'workspace.closeTab': '关闭标签',
+  'workspace.preview': '预览',
+  'workspace.previewEmpty': '选择一个文件进行预览。',
+  'workspace.notGitRepo': '当前目录不是 Git 仓库。',
+  'workspace.missingWorkdir': '工作目录不存在。',
+  'workspace.loadError': '工作区数据加载失败。',
+  'workspace.noChanges': '没有变更',
+  'workspace.noFiles': '没有文件',
+  'workspace.noMatchingFiles': '没有匹配的文件',
+  'workspace.previewKind.diff': 'Diff',
+  'workspace.previewKind.file': '文件',
+  'workspace.previewState.loading': '正在加载预览...',
+  'workspace.previewState.binary': '二进制文件暂不支持预览。',
+  'workspace.previewState.tooLarge': '文件过大，无法预览。',
+  'workspace.previewState.missing': '文件不存在。',
+  'workspace.imagePreviewUnavailable': '图片无法预览。',
+  'workspace.previewLineLimit': '仅显示前 {count} 行。完整内容请在编辑器中打开。',
+  'workspace.addToChat': '添加到聊天',
+  'workspace.copyPath': '复制路径',
+  'workspace.localComment': '本地评论',
+  'workspace.commentLine': '评论第 {line} 行',
+  'workspace.commentLineTarget': '第 {line} 行',
+  'workspace.commentPlaceholder': '描述你希望这里怎么改...',
+  'workspace.addCommentToChat': '添加评论',
+
   // ─── Status Bar ──────────────────────────────────────
   'status.connected': '已连接',
   'status.connecting': '连接中...',
@@ -522,6 +557,7 @@ export const zh: Record<TranslationKey, string> = {
   'chat.placeholder': '让 Claude 编辑、调试或解释代码...',
   'chat.placeholderMissing': '此会话指向的工作目录缺失。请新建会话或选择其他项目。',
   'chat.addFiles': '添加文件或图片',
+  'chat.workspaceReferencesOnly': '已添加 {count} 个工作区引用',
   'chat.slashCommands': '斜杠命令',
   'slash.mcp.title': '可用 MCP 工具',
   'slash.mcp.subtitle': '展示当前聊天上下文里的全局 MCP 和当前项目 MCP。',
@@ -612,23 +648,21 @@ export const zh: Record<TranslationKey, string> = {
   'chat.select': '选择',
   'chat.dismiss': '关闭',
   'chat.stopTitle': '停止生成 (Cmd+.)',
-  'chat.rewindAction': '回滚到这里',
-  'chat.rewindModalTitle': '回滚对话',
-  'chat.rewindConfirm': '执行回滚',
-  'chat.rewindPromptLabel': '目标提示词',
-  'chat.rewindAttachmentOnly': '这条消息只包含附件。',
-  'chat.rewindLoading': '正在检查这一轮的文件检查点...',
-  'chat.rewindConversationCardTitle': '对话回滚',
-  'chat.rewindConversationCardBody': '移除这条提示词以及其后的 {count} 条活跃消息，并把输入框恢复到这个位置。',
-  'chat.rewindCodeCardTitle': '代码回滚',
-  'chat.rewindCodeFiles': '将恢复 {count} 个文件',
-  'chat.rewindCodeInsertions': '将移除 {count} 行新增',
-  'chat.rewindCodeDeletions': '将恢复 {count} 行删除',
-  'chat.rewindCodeUnavailable': '这条提示词没有可用的文件检查点，仍然可以只回滚对话。',
-  'chat.rewindFilesLabel': '受影响文件',
-  'chat.rewindFilesMore': '另有 {count} 个',
   'chat.rewindSuccessWithCode': '已回滚 {count} 条消息，并恢复相关文件。',
   'chat.rewindSuccessConversationOnly': '已回滚 {count} 条消息。这一轮没有可用的文件检查点。',
+  'chat.turnChangesCardLabel': '当前轮次已更改文件',
+  'chat.turnChangesTitle': '{count} 个文件已更改',
+  'chat.turnChangesSubtitle': '当前轮次检查点',
+  'chat.turnChangesUndo': '撤销',
+  'chat.turnChangesUndoing': '正在撤销...',
+  'chat.turnChangesUndoAria': '撤销当前轮次变更',
+  'chat.turnChangesConfirmTitle': '撤销当前轮次？',
+  'chat.turnChangesConfirmBody': '这会回滚最近一次助手回复，并恢复这一轮中被跟踪的文件变更。',
+  'chat.turnChangesConfirmUndo': '撤销当前轮次',
+  'chat.turnChangesShowDiffAria': '查看 {path} 的 diff',
+  'chat.turnChangesHideDiffAria': '收起 {path} 的 diff',
+  'chat.turnChangesDiffLoading': '正在加载 diff...',
+  'chat.turnChangesDiffUnavailable': 'Diff 不可用。',
 
   // ─── Streaming Indicator ──────────────────────────────────────
   'streaming.thinking': '思考中',
@@ -985,4 +1019,7 @@ export const zh: Record<TranslationKey, string> = {
   'tabs.closeConfirmMessage': '此会话仍在运行，你想要怎么做？',
   'tabs.closeConfirmKeep': '保持运行',
   'tabs.closeConfirmStop': '停止并关闭',
+  'tabs.openTerminal': '打开终端',
+  'tabs.showWorkspace': '显示工作区',
+  'tabs.hideWorkspace': '隐藏工作区',
 }

desktop/src/pages/ActiveSession.test.tsx

@@ -1,14 +1,18 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
-import { render } from '@testing-library/react'
+import { fireEvent, render, screen, within } from '@testing-library/react'
 import '@testing-library/jest-dom'
 import { act } from 'react'
 
 vi.mock('../components/chat/MessageList', () => ({
-  MessageList: () => <div data-testid="message-list" />,
+  MessageList: ({ compact }: { compact?: boolean }) => (
+    <div data-testid="message-list" data-compact={compact ? 'true' : 'false'} />
+  ),
 }))
 
 vi.mock('../components/chat/ChatInput', () => ({
-  ChatInput: () => <div data-testid="chat-input" />,
+  ChatInput: ({ compact, variant }: { compact?: boolean; variant?: string }) => (
+    <div data-testid="chat-input" data-compact={compact ? 'true' : 'false'} data-variant={variant} />
+  ),
 }))
 
 vi.mock('../components/teams/TeamStatusBar', () => ({
@@ -19,12 +23,20 @@ vi.mock('../components/chat/SessionTaskBar', () => ({
   SessionTaskBar: () => <div data-testid="session-task-bar" />,
 }))
 
+vi.mock('../components/workspace/WorkspacePanel', () => ({
+  WorkspacePanel: ({ sessionId }: { sessionId: string }) => (
+    <div data-testid="workspace-panel">workspace:{sessionId}</div>
+  ),
+}))
+
 import { ActiveSession } from './ActiveSession'
 import { useChatStore } from '../stores/chatStore'
 import { useCLITaskStore } from '../stores/cliTaskStore'
 import { useSessionStore } from '../stores/sessionStore'
 import { useTabStore } from '../stores/tabStore'
 import { useTeamStore } from '../stores/teamStore'
+import { useWorkspacePanelStore } from '../stores/workspacePanelStore'
+import { WORKSPACE_PANEL_DEFAULT_WIDTH } from '../stores/workspacePanelStore'
 
 afterEach(() => {
   vi.useRealTimers()
@@ -32,6 +44,7 @@ afterEach(() => {
   useSessionStore.setState({ sessions: [], activeSessionId: null, isLoading: false, error: null })
   useChatStore.setState({ sessions: {} })
   useTeamStore.setState({ teams: [], activeTeam: null, memberColors: new Map(), error: null })
+  useWorkspacePanelStore.setState(useWorkspacePanelStore.getInitialState(), true)
 })
 
 describe('ActiveSession task polling', () => {
@@ -178,4 +191,180 @@ describe('ActiveSession task polling', () => {
     unmount()
     useCLITaskStore.setState(originalCliTaskState)
   })
+
+  it('renders the workspace panel to the right of chat and supports resizing', () => {
+    const sessionId = 'workspace-session'
+
+    useSessionStore.setState({
+      sessions: [{
+        id: sessionId,
+        title: 'Workspace Session',
+        createdAt: '2026-04-10T00:00:00.000Z',
+        modifiedAt: '2026-04-10T00:00:00.000Z',
+        messageCount: 1,
+        projectPath: '',
+        workDir: '/tmp/project',
+        workDirExists: true,
+      }],
+      activeSessionId: sessionId,
+      isLoading: false,
+      error: null,
+    })
+    useTabStore.setState({
+      tabs: [{ sessionId, title: 'Workspace Session', type: 'session', status: 'idle' }],
+      activeTabId: sessionId,
+    })
+    useChatStore.setState({
+      sessions: {
+        [sessionId]: {
+          messages: [{ id: 'msg-1', type: 'assistant_text', content: 'hello', timestamp: 1 }],
+          chatState: 'idle',
+          connectionState: 'connected',
+          streamingText: '',
+          streamingToolInput: '',
+          activeToolUseId: null,
+          activeToolName: null,
+          activeThinkingId: null,
+          pendingPermission: null,
+          pendingComputerUsePermission: null,
+          tokenUsage: { input_tokens: 0, output_tokens: 0 },
+          elapsedSeconds: 0,
+          statusVerb: '',
+          slashCommands: [],
+          agentTaskNotifications: {},
+          elapsedTimer: null,
+        },
+      },
+    })
+    useWorkspacePanelStore.getState().openPanel(sessionId)
+
+    render(<ActiveSession />)
+
+    const contentRow = screen.getByTestId('active-session-content-row')
+    const chatColumn = screen.getByTestId('active-session-chat-column')
+    const resizeHandle = screen.getByTestId('workspace-resize-handle')
+
+    expect(within(contentRow).getByTestId('message-list')).toBeInTheDocument()
+    expect(within(contentRow).getByTestId('message-list')).toHaveAttribute('data-compact', 'true')
+    expect(within(contentRow).getByTestId('workspace-panel')).toHaveTextContent(`workspace:${sessionId}`)
+    expect(within(chatColumn).getByTestId('chat-input')).toBeInTheDocument()
+    expect(within(chatColumn).getByTestId('chat-input')).toHaveAttribute('data-compact', 'true')
+    expect(chatColumn).toHaveClass('flex-1')
+    expect(chatColumn).not.toHaveClass('shrink-0')
+    expect(contentRow.children[0]).toBe(chatColumn)
+    expect(contentRow.children[1]).toBe(resizeHandle)
+    expect(contentRow.children[2]).toBe(screen.getByTestId('workspace-panel'))
+
+    act(() => {
+      fireEvent.keyDown(resizeHandle, { key: 'ArrowLeft' })
+    })
+
+    expect(useWorkspacePanelStore.getState().width).toBe(WORKSPACE_PANEL_DEFAULT_WIDTH + 32)
+  })
+
+  it('does not render the workspace panel when closed or for member sessions', () => {
+    const regularSessionId = 'regular-session'
+
+    useSessionStore.setState({
+      sessions: [{
+        id: regularSessionId,
+        title: 'Regular Session',
+        createdAt: '2026-04-10T00:00:00.000Z',
+        modifiedAt: '2026-04-10T00:00:00.000Z',
+        messageCount: 0,
+        projectPath: '',
+        workDir: '/tmp/project',
+        workDirExists: true,
+      }],
+      activeSessionId: regularSessionId,
+      isLoading: false,
+      error: null,
+    })
+    useTabStore.setState({
+      tabs: [{ sessionId: regularSessionId, title: 'Regular Session', type: 'session', status: 'idle' }],
+      activeTabId: regularSessionId,
+    })
+    useChatStore.setState({
+      sessions: {
+        [regularSessionId]: {
+          messages: [],
+          chatState: 'idle',
+          connectionState: 'connected',
+          streamingText: '',
+          streamingToolInput: '',
+          activeToolUseId: null,
+          activeToolName: null,
+          activeThinkingId: null,
+          pendingPermission: null,
+          pendingComputerUsePermission: null,
+          tokenUsage: { input_tokens: 0, output_tokens: 0 },
+          elapsedSeconds: 0,
+          statusVerb: '',
+          slashCommands: [],
+          agentTaskNotifications: {},
+          elapsedTimer: null,
+        },
+      },
+    })
+
+    const { rerender } = render(<ActiveSession />)
+    expect(screen.queryByTestId('workspace-panel')).not.toBeInTheDocument()
+
+    const memberSessionId = 'team-member:security-reviewer@test-team'
+    useTeamStore.setState({
+      teams: [],
+      activeTeam: {
+        name: 'test-team',
+        leadAgentId: 'team-lead@test-team',
+        leadSessionId: 'leader-session',
+        members: [
+          {
+            agentId: 'team-lead@test-team',
+            role: 'team-lead',
+            status: 'running',
+            sessionId: 'leader-session',
+          },
+          {
+            agentId: 'security-reviewer@test-team',
+            role: 'security-reviewer',
+            status: 'running',
+          },
+        ],
+      },
+      memberColors: new Map(),
+      error: null,
+    })
+    useTabStore.setState({
+      tabs: [{ sessionId: memberSessionId, title: 'security-reviewer', type: 'session', status: 'idle' }],
+      activeTabId: memberSessionId,
+    })
+    useChatStore.setState({
+      sessions: {
+        [memberSessionId]: {
+          messages: [{ id: 'msg-2', type: 'assistant_text', content: 'hello', timestamp: 1 }],
+          chatState: 'idle',
+          connectionState: 'connected',
+          streamingText: '',
+          streamingToolInput: '',
+          activeToolUseId: null,
+          activeToolName: null,
+          activeThinkingId: null,
+          pendingPermission: null,
+          pendingComputerUsePermission: null,
+          tokenUsage: { input_tokens: 0, output_tokens: 0 },
+          elapsedSeconds: 0,
+          statusVerb: '',
+          slashCommands: [],
+          agentTaskNotifications: {},
+          elapsedTimer: null,
+        },
+      },
+    })
+    useWorkspacePanelStore.getState().openPanel(memberSessionId)
+
+    rerender(<ActiveSession />)
+
+    expect(screen.queryByTestId('workspace-panel')).not.toBeInTheDocument()
+    expect(screen.getByTestId('message-list')).toBeInTheDocument()
+  })
 })

desktop/src/pages/ActiveSession.tsx

@@ -1,20 +1,95 @@
-import { useEffect, useMemo } from 'react'
+import { useEffect, useMemo, useRef, useState } from 'react'
 import { useTabStore } from '../stores/tabStore'
 import { useSessionStore } from '../stores/sessionStore'
 import { useChatStore } from '../stores/chatStore'
 import { useCLITaskStore } from '../stores/cliTaskStore'
 import { useTeamStore } from '../stores/teamStore'
+import { useWorkspacePanelStore } from '../stores/workspacePanelStore'
 import { useTranslation } from '../i18n'
 import { MessageList } from '../components/chat/MessageList'
 import { ChatInput } from '../components/chat/ChatInput'
 import { ComputerUsePermissionModal } from '../components/chat/ComputerUsePermissionModal'
-import { TeamStatusBar } from '../components/teams/TeamStatusBar'
 import { SessionTaskBar } from '../components/chat/SessionTaskBar'
+import { WorkspacePanel } from '../components/workspace/WorkspacePanel'
+import { TeamStatusBar } from '../components/teams/TeamStatusBar'
 
 const TASK_POLL_INTERVAL_MS = 1000
+const WORKSPACE_RESIZE_STEP = 32
+const CHAT_COLUMN_WITH_WORKSPACE_CLASS =
+  'min-w-[320px] flex-1 border-r border-[var(--color-border)] bg-[var(--color-surface)]'
+
+function WorkspaceResizeHandle() {
+  const t = useTranslation()
+  const width = useWorkspacePanelStore((state) => state.width)
+  const setWidth = useWorkspacePanelStore((state) => state.setWidth)
+  const [dragState, setDragState] = useState<{ startX: number; startWidth: number } | null>(null)
+  const dragStateRef = useRef(dragState)
+
+  useEffect(() => {
+    dragStateRef.current = dragState
+  }, [dragState])
+
+  useEffect(() => {
+    if (!dragState) return
+
+    const handlePointerMove = (event: PointerEvent) => {
+      const current = dragStateRef.current
+      if (!current) return
+      setWidth(current.startWidth + current.startX - event.clientX)
+    }
+
+    const handlePointerUp = () => {
+      setDragState(null)
+    }
+
+    document.body.style.cursor = 'col-resize'
+    document.body.style.userSelect = 'none'
+    window.addEventListener('pointermove', handlePointerMove)
+    window.addEventListener('pointerup', handlePointerUp)
+    window.addEventListener('pointercancel', handlePointerUp)
+
+    return () => {
+      document.body.style.cursor = ''
+      document.body.style.userSelect = ''
+      window.removeEventListener('pointermove', handlePointerMove)
+      window.removeEventListener('pointerup', handlePointerUp)
+      window.removeEventListener('pointercancel', handlePointerUp)
+    }
+  }, [dragState, setWidth])
+
+  return (
+    <div
+      role="separator"
+      aria-label={t('workspace.resizePanel')}
+      aria-orientation="vertical"
+      aria-valuenow={width}
+      tabIndex={0}
+      data-testid="workspace-resize-handle"
+      onPointerDown={(event) => {
+        if (event.button !== 0) return
+        event.preventDefault()
+        setDragState({ startX: event.clientX, startWidth: width })
+      }}
+      onKeyDown={(event) => {
+        if (event.key === 'ArrowLeft') {
+          event.preventDefault()
+          setWidth(width + WORKSPACE_RESIZE_STEP)
+        }
+        if (event.key === 'ArrowRight') {
+          event.preventDefault()
+          setWidth(width - WORKSPACE_RESIZE_STEP)
+        }
+      }}
+      className="group relative z-10 flex w-2 shrink-0 cursor-col-resize items-stretch justify-center bg-[var(--color-surface)] outline-none focus-visible:bg-[var(--color-surface-container)]"
+    >
+      <div className="my-3 w-px rounded-full bg-[var(--color-border)] transition-colors group-hover:bg-[var(--color-border-focus)] group-focus-visible:bg-[var(--color-border-focus)]" />
+    </div>
+  )
+}
 
 export function ActiveSession() {
   const activeTabId = useTabStore((s) => s.activeTabId)
+  const activeTabType = useTabStore((s) => s.tabs.find((tab) => tab.sessionId === s.activeTabId)?.type ?? null)
   const sessions = useSessionStore((s) => s.sessions)
   const connectToSession = useChatStore((s) => s.connectToSession)
   const sessionState = useChatStore((s) => activeTabId ? s.sessions[activeTabId] : undefined)
@@ -29,6 +104,11 @@ export function ActiveSession() {
   const memberInfo = useTeamStore((s) => activeTabId ? s.getMemberBySessionId(activeTabId) : null)
   const activeTeam = useTeamStore((s) => s.activeTeam)
   const isMemberSession = !!memberInfo
+  const showWorkspacePanel = useWorkspacePanelStore((state) =>
+    activeTabId && activeTabType === 'session' && !isMemberSession
+      ? state.isPanelOpen(activeTabId)
+      : false,
+  )
 
   useEffect(() => {
     if (activeTabId && !isMemberSession) {
@@ -81,132 +161,167 @@ export function ActiveSession() {
   if (!activeTabId) return null
 
   return (
-    <div className="flex-1 flex flex-col relative overflow-hidden bg-background text-on-surface">
-      {isMemberSession && (
-        <div className="shrink-0 border-b border-[var(--color-border)] bg-[var(--color-surface-container)]">
-          <div className="mx-auto max-w-[860px] flex items-center justify-between gap-4 px-8 py-2">
-            <div className="min-w-0">
-              <div className="flex items-center gap-3">
-                {memberInfo?.status === 'running' && (
-                  <span className="flex h-2 w-2 rounded-full bg-[var(--color-warning)] animate-pulse-dot" />
-                )}
-                {memberInfo?.status === 'completed' && (
-                  <span className="material-symbols-outlined text-[14px] text-[var(--color-success)]" style={{ fontVariationSettings: "'FILL' 1" }}>check_circle</span>
-                )}
-                <span className="material-symbols-outlined text-[14px] text-[var(--color-text-tertiary)]">smart_toy</span>
-                <span className="text-sm font-semibold text-[var(--color-text-primary)]">
-                  {memberInfo?.role}
-                </span>
-                {activeTeam && (
-                  <span className="text-[10px] text-[var(--color-text-tertiary)]">
-                    @ {activeTeam.name}
-                  </span>
-                )}
-              </div>
-              <p className="mt-1 text-[11px] text-[var(--color-text-tertiary)]">
-                {t('teams.memberSessionHint')}
-              </p>
-            </div>
-            <button
-              onClick={() => {
-                if (activeTeam?.leadSessionId) {
-                  useTabStore.getState().openTab(
-                    activeTeam.leadSessionId,
-                    t('teams.leader'),
-                    'session',
-                  )
-                }
-              }}
-              disabled={!activeTeam?.leadSessionId}
-              className="flex shrink-0 items-center gap-1 text-xs font-medium text-[var(--color-text-secondary)] hover:text-[var(--color-text-primary)] transition-colors disabled:opacity-50 disabled:hover:text-[var(--color-text-secondary)]"
-            >
-              <span className="material-symbols-outlined text-[14px]">arrow_back</span>
-              {t('teams.backToLeader')}
-            </button>
-          </div>
-        </div>
-      )}
-
-      {isEmpty ? (
-        <div className="flex flex-1 flex-col items-center justify-center p-8 pb-32">
-          <div className="flex max-w-md flex-col items-center text-center">
-            {isMemberSession ? (
-              <>
-                <span className="material-symbols-outlined text-[48px] mb-4 text-[var(--color-text-tertiary)]">smart_toy</span>
-                <p className="text-[var(--color-text-secondary)]">
-                  {memberInfo?.status === 'running'
-                    ? `${memberInfo.role} ${t('teams.working')}`
-                    : t('teams.noMessages')}
-                </p>
-              </>
-            ) : (
-              <>
-                <img src="/app-icon.png" alt="Claude Code Haha" className="mb-6 h-24 w-24" />
-                <h1 className="mb-2 text-3xl font-extrabold tracking-tight text-[var(--color-text-primary)]" style={{ fontFamily: 'var(--font-headline)' }}>
-                  {t('empty.title')}
-                </h1>
-                <p className="mx-auto max-w-xs text-[var(--color-text-secondary)]" style={{ fontFamily: 'var(--font-body)' }}>
-                  {t('empty.subtitle')}
-                </p>
-              </>
-            )}
-          </div>
-        </div>
-      ) : (
-        <>
-          {!isMemberSession && (
-            <div className="mx-auto flex w-full max-w-[860px] items-center border-b border-outline-variant/10 px-8 py-3">
-              <div className="flex-1">
-                <h1 className="text-lg font-bold font-headline text-on-surface leading-tight">
-                  {session?.title || t('session.untitled')}
-                </h1>
-                <div className="flex items-center gap-2 text-[10px] text-outline font-medium mt-1">
-                  {isActive && (
-                    <span className="flex items-center gap-1">
-                      <span className="w-1.5 h-1.5 rounded-full bg-[var(--color-success)] animate-pulse-dot" />
-                      {t('session.active')}
-                    </span>
-                  )}
-                  {totalTokens > 0 && (
-                    <>
-                      <span className="text-[var(--color-outline)]">·</span>
-                      <span>{totalTokens.toLocaleString()} t</span>
-                    </>
-                  )}
-                  {lastUpdated && (
-                    <>
-                      <span className="text-[var(--color-outline)]">·</span>
-                      <span>{t('session.lastUpdated', { time: lastUpdated })}</span>
-                    </>
-                  )}
-                  {session?.messageCount !== undefined && session.messageCount > 0 && (
-                    <>
-                      <span className="text-[var(--color-outline)]">·</span>
-                      <span>{t('session.messages', { count: session.messageCount })}</span>
-                    </>
-                  )}
-                </div>
-                {session?.workDirExists === false && (
-                  <div className="mt-2 inline-flex max-w-full items-center gap-2 rounded-lg border border-[var(--color-error)]/20 bg-[var(--color-error)]/8 px-3 py-1.5 text-[11px] text-[var(--color-error)]">
-                    <span className="material-symbols-outlined text-[14px]">warning</span>
-                    <span className="truncate">
-                      {t('session.workspaceUnavailable', { dir: session.workDir || 'directory no longer exists' })}
+    <div className="flex-1 flex relative overflow-hidden bg-background text-on-surface">
+      <div data-testid="active-session-content-row" className="flex min-h-0 min-w-0 flex-1">
+        <div
+          data-testid="active-session-chat-column"
+          className={`flex flex-col ${showWorkspacePanel ? CHAT_COLUMN_WITH_WORKSPACE_CLASS : 'min-w-[360px] flex-1'}`}
+        >
+          {isMemberSession && (
+            <div className="shrink-0 border-b border-[var(--color-border)] bg-[var(--color-surface-container)]">
+              <div className="mx-auto max-w-[860px] flex items-center justify-between gap-4 px-8 py-2">
+                <div className="min-w-0">
+                  <div className="flex items-center gap-3">
+                    {memberInfo?.status === 'running' && (
+                      <span className="flex h-2 w-2 rounded-full bg-[var(--color-warning)] animate-pulse-dot" />
+                    )}
+                    {memberInfo?.status === 'completed' && (
+                      <span className="material-symbols-outlined text-[14px] text-[var(--color-success)]" style={{ fontVariationSettings: "'FILL' 1" }}>check_circle</span>
+                    )}
+                    <span className="material-symbols-outlined text-[14px] text-[var(--color-text-tertiary)]">smart_toy</span>
+                    <span className="text-sm font-semibold text-[var(--color-text-primary)]">
+                      {memberInfo?.role}
                     </span>
+                    {activeTeam && (
+                      <span className="text-[10px] text-[var(--color-text-tertiary)]">
+                        @ {activeTeam.name}
+                      </span>
+                    )}
                   </div>
-                )}
+                  <p className="mt-1 text-[11px] text-[var(--color-text-tertiary)]">
+                    {t('teams.memberSessionHint')}
+                  </p>
+                </div>
+                <button
+                  onClick={() => {
+                    if (activeTeam?.leadSessionId) {
+                      useTabStore.getState().openTab(
+                        activeTeam.leadSessionId,
+                        t('teams.leader'),
+                        'session',
+                      )
+                    }
+                  }}
+                  disabled={!activeTeam?.leadSessionId}
+                  className="flex shrink-0 items-center gap-1 text-xs font-medium text-[var(--color-text-secondary)] hover:text-[var(--color-text-primary)] transition-colors disabled:opacity-50 disabled:hover:text-[var(--color-text-secondary)]"
+                >
+                  <span className="material-symbols-outlined text-[14px]">arrow_back</span>
+                  {t('teams.backToLeader')}
+                </button>
               </div>
             </div>
           )}
 
-          <MessageList />
-        </>
-      )}
+          {isEmpty ? (
+            <div className="flex flex-1 flex-col items-center justify-center p-8 pb-32">
+              <div className="flex max-w-md flex-col items-center text-center">
+                {isMemberSession ? (
+                  <>
+                    <span className="material-symbols-outlined text-[48px] mb-4 text-[var(--color-text-tertiary)]">smart_toy</span>
+                    <p className="text-[var(--color-text-secondary)]">
+                      {memberInfo?.status === 'running'
+                        ? `${memberInfo.role} ${t('teams.working')}`
+                        : t('teams.noMessages')}
+                    </p>
+                  </>
+                ) : (
+                  <>
+                    <img src="/app-icon.png" alt="Claude Code Haha" className="mb-6 h-24 w-24" />
+                    <h1 className="mb-2 text-3xl font-extrabold tracking-tight text-[var(--color-text-primary)]" style={{ fontFamily: 'var(--font-headline)' }}>
+                      {t('empty.title')}
+                    </h1>
+                    <p className="mx-auto max-w-xs text-[var(--color-text-secondary)]" style={{ fontFamily: 'var(--font-body)' }}>
+                      {t('empty.subtitle')}
+                    </p>
+                  </>
+                )}
+              </div>
+            </div>
+          ) : (
+            <>
+              {!isMemberSession && (
+                <div
+                  className={
+                    showWorkspacePanel
+                      ? 'flex w-full items-center border-b border-[var(--color-border)]/70 px-4 py-3'
+                      : 'mx-auto flex w-full max-w-[860px] items-center border-b border-outline-variant/10 px-8 py-3'
+                  }
+                >
+                  <div className="min-w-0 flex-1">
+                    <h1
+                      className={
+                        showWorkspacePanel
+                          ? 'truncate text-[15px] font-bold font-headline leading-tight text-on-surface'
+                          : 'text-lg font-bold font-headline text-on-surface leading-tight'
+                      }
+                    >
+                      {session?.title || t('session.untitled')}
+                    </h1>
+                    <div
+                      className={
+                        showWorkspacePanel
+                          ? 'mt-1 flex min-w-0 items-center gap-1.5 overflow-hidden whitespace-nowrap text-[10px] font-medium text-outline'
+                          : 'flex items-center gap-2 text-[10px] text-outline font-medium mt-1'
+                      }
+                    >
+                      {isActive && (
+                        <span className="flex shrink-0 items-center gap-1">
+                          <span className="w-1.5 h-1.5 rounded-full bg-[var(--color-success)] animate-pulse-dot" />
+                          {t('session.active')}
+                        </span>
+                      )}
+                      {totalTokens > 0 && (
+                        <>
+                          <span className="text-[var(--color-outline)]">·</span>
+                          <span>{totalTokens.toLocaleString()} t</span>
+                        </>
+                      )}
+                      {lastUpdated && (
+                        <>
+                          <span className="shrink-0 text-[var(--color-outline)]">·</span>
+                          <span className="truncate">{t('session.lastUpdated', { time: lastUpdated })}</span>
+                        </>
+                      )}
+                      {!showWorkspacePanel && session?.messageCount !== undefined && session.messageCount > 0 && (
+                        <>
+                          <span className="text-[var(--color-outline)]">·</span>
+                          <span>{t('session.messages', { count: session.messageCount })}</span>
+                        </>
+                      )}
+                    </div>
+                    {session?.workDirExists === false && (
+                      <div className="mt-2 inline-flex max-w-full items-center gap-2 rounded-lg border border-[var(--color-error)]/20 bg-[var(--color-error)]/8 px-3 py-1.5 text-[11px] text-[var(--color-error)]">
+                        <span className="material-symbols-outlined text-[14px]">warning</span>
+                        <span className="truncate">
+                          {t('session.workspaceUnavailable', { dir: session.workDir || 'directory no longer exists' })}
+                        </span>
+                      </div>
+                    )}
+                  </div>
+                </div>
+              )}
 
-      {!isMemberSession && <SessionTaskBar />}
+              <MessageList compact={showWorkspacePanel} />
+            </>
+          )}
 
-      <TeamStatusBar />
+          {!isMemberSession && <SessionTaskBar />}
 
-      <ChatInput variant={isEmpty && !isMemberSession ? 'hero' : 'default'} />
+          <TeamStatusBar />
+
+          <ChatInput
+            variant={isEmpty && !isMemberSession && !showWorkspacePanel ? 'hero' : 'default'}
+            compact={showWorkspacePanel}
+          />
+        </div>
+
+        {showWorkspacePanel ? (
+          <>
+            <WorkspaceResizeHandle />
+            <WorkspacePanel sessionId={activeTabId} />
+          </>
+        ) : null}
+      </div>
 
       {!isMemberSession && activeTabId ? (
         <ComputerUsePermissionModal

desktop/src/stores/chatStore.test.ts

@@ -231,6 +231,117 @@ describe('chatStore history mapping', () => {
     ])
   })
 
+  it('restores CLI file mentions as visible attachment chips from transcript history', () => {
+    const messages: MessageEntry[] = [
+      {
+        id: 'user-with-file-mention',
+        type: 'user',
+        timestamp: '2026-04-06T00:00:00.000Z',
+        content: '@"/private/tmp/example/src/sentinel.ts" 这个常量是什么？',
+      },
+    ]
+
+    const mapped = mapHistoryMessagesToUiMessages(messages)
+
+    expect(mapped).toMatchObject([
+      {
+        id: 'user-with-file-mention',
+        type: 'user_text',
+        content: '这个常量是什么？',
+        modelContent: '@"/private/tmp/example/src/sentinel.ts" 这个常量是什么？',
+        attachments: [{
+          type: 'file',
+          name: 'sentinel.ts',
+          path: '/private/tmp/example/src/sentinel.ts',
+        }],
+      },
+    ])
+  })
+
+  it('keeps workspace reference chips visible while sending CLI attachment paths', () => {
+    useChatStore.setState({
+      sessions: {
+        [TEST_SESSION_ID]: {
+          messages: [],
+          chatState: 'idle',
+          connectionState: 'connected',
+          streamingText: '',
+          streamingToolInput: '',
+          activeToolUseId: null,
+          activeToolName: null,
+          activeThinkingId: null,
+          pendingPermission: null,
+          pendingComputerUsePermission: null,
+          tokenUsage: { input_tokens: 0, output_tokens: 0 },
+          elapsedSeconds: 0,
+          statusVerb: '',
+          slashCommands: [],
+          agentTaskNotifications: {},
+          elapsedTimer: null,
+        },
+      },
+    })
+
+    useChatStore.getState().sendMessage(
+      TEST_SESSION_ID,
+      'Notes for attached workspace files:\n- src/App.tsx:L4\n  Comment: tighten this',
+      [{
+        type: 'file',
+        name: 'App.tsx',
+        path: '/repo/src/App.tsx',
+        lineStart: 4,
+        lineEnd: 4,
+        note: 'tighten this',
+        quote: 'const value = 1',
+      }],
+      {
+        displayContent: '改这里',
+        displayAttachments: [{
+          type: 'file',
+          name: 'App.tsx',
+          path: 'src/App.tsx',
+          lineStart: 4,
+          lineEnd: 4,
+          note: 'tighten this',
+          quote: 'const value = 1',
+        }],
+      },
+    )
+
+    expect(useChatStore.getState().sessions[TEST_SESSION_ID]?.messages).toMatchObject([
+      {
+        type: 'user_text',
+        content: '改这里',
+        modelContent: 'Notes for attached workspace files:\n- src/App.tsx:L4\n  Comment: tighten this',
+        attachments: [{
+          type: 'file',
+          name: 'App.tsx',
+          path: 'src/App.tsx',
+          lineStart: 4,
+          lineEnd: 4,
+          note: 'tighten this',
+          quote: 'const value = 1',
+        }],
+      },
+    ])
+    expect(sendMock).toHaveBeenCalledWith(
+      TEST_SESSION_ID,
+      {
+        type: 'user_message',
+        content: 'Notes for attached workspace files:\n- src/App.tsx:L4\n  Comment: tighten this',
+        attachments: [{
+          type: 'file',
+          name: 'App.tsx',
+          path: '/repo/src/App.tsx',
+          lineStart: 4,
+          lineEnd: 4,
+          note: 'tighten this',
+          quote: 'const value = 1',
+        }],
+      },
+    )
+  })
+
   it('keeps parent tool linkage for live tool events', () => {
     // Initialize the session first
     useChatStore.setState({

desktop/src/stores/chatStore.ts

@@ -92,7 +92,7 @@ type ChatStore = {
     sessionId: string,
     content: string,
     attachments?: AttachmentRef[],
-    options?: { displayContent?: string },
+    options?: { displayContent?: string; displayAttachments?: AttachmentRef[] },
   ) => void
   respondToPermission: (
     sessionId: string,
@@ -265,13 +265,19 @@ export const useChatStore = create<ChatStore>((set, get) => ({
     const userFacingContent =
       options?.displayContent?.trim() || content.trim()
     const isMemberSession = !!useTeamStore.getState().getMemberBySessionId(sessionId)
+    const visibleAttachments = options?.displayAttachments ?? attachments
     const uiAttachments: UIAttachment[] | undefined =
-      attachments && attachments.length > 0
-        ? attachments.map((a) => ({
+      visibleAttachments && visibleAttachments.length > 0
+        ? visibleAttachments.map((a) => ({
             type: a.type,
             name: a.name || a.path || a.mimeType || a.type,
+            path: a.path,
             data: a.data,
             mimeType: a.mimeType,
+            lineStart: a.lineStart,
+            lineEnd: a.lineEnd,
+            note: a.note,
+            quote: a.quote,
           }))
         : undefined
 
@@ -309,6 +315,7 @@ export const useChatStore = create<ChatStore>((set, get) => ({
         id: nextId(),
         type: 'user_text',
         content: userFacingContent,
+        ...(userFacingContent !== content ? { modelContent: content } : {}),
         attachments: isMemberSession ? undefined : uiAttachments,
         timestamp: Date.now(),
         ...(isMemberSession ? { pending: true } : {}),
@@ -918,6 +925,43 @@ type HistoryMappingOptions = {
   includeTeammateMessages?: boolean
 }
 
+function getReferenceName(referencePath: string): string {
+  const normalized = referencePath.replace(/\\/g, '/').replace(/\/+$/, '')
+  const name = normalized.split('/').filter(Boolean).pop()
+  return name || referencePath
+}
+
+function extractLeadingFileReferences(text: string): {
+  content: string
+  attachments?: UIAttachment[]
+  modelContent?: string
+} {
+  const attachments: UIAttachment[] = []
+  let remaining = text
+
+  while (true) {
+    const match = remaining.match(/^@"([^"]+)"\s*/)
+    if (!match?.[1]) break
+
+    attachments.push({
+      type: 'file',
+      name: getReferenceName(match[1]),
+      path: match[1],
+    })
+    remaining = remaining.slice(match[0].length)
+  }
+
+  if (attachments.length === 0) {
+    return { content: text }
+  }
+
+  return {
+    content: remaining.trimStart(),
+    attachments,
+    modelContent: text,
+  }
+}
+
 /**
  * Reconstruct agentTaskNotifications from history.
  *
@@ -1013,7 +1057,15 @@ export function mapHistoryMessagesToUiMessages(
         })
         continue
       }
-      uiMessages.push({ id: msg.id || nextId(), type: 'user_text', content: msg.content, timestamp })
+      const parsed = extractLeadingFileReferences(msg.content)
+      uiMessages.push({
+        id: msg.id || nextId(),
+        type: 'user_text',
+        content: parsed.content,
+        ...(parsed.modelContent ? { modelContent: parsed.modelContent } : {}),
+        ...(parsed.attachments ? { attachments: parsed.attachments } : {}),
+        timestamp,
+      })
       continue
     }
     if (msg.type === 'assistant' && typeof msg.content === 'string') {
@@ -1043,7 +1095,16 @@ export function mapHistoryMessagesToUiMessages(
         else if (block.type === 'tool_result') uiMessages.push({ id: nextId(), type: 'tool_result', toolUseId: block.tool_use_id ?? '', content: block.content, isError: !!block.is_error, timestamp, parentToolUseId: msg.parentToolUseId })
       }
       if (textParts.length > 0 || attachments.length > 0) {
-        uiMessages.push({ id: msg.id || nextId(), type: 'user_text', content: textParts.join('\n'), attachments: attachments.length > 0 ? attachments : undefined, timestamp })
+        const parsed = extractLeadingFileReferences(textParts.join('\n'))
+        const allAttachments = [...(parsed.attachments ?? []), ...attachments]
+        uiMessages.push({
+          id: msg.id || nextId(),
+          type: 'user_text',
+          content: parsed.content,
+          ...(parsed.modelContent ? { modelContent: parsed.modelContent } : {}),
+          attachments: allAttachments.length > 0 ? allAttachments : undefined,
+          timestamp,
+        })
       }
     }
   }

desktop/src/stores/workspaceChatContextStore.test.ts

@@ -0,0 +1,69 @@
+import { beforeEach, describe, expect, it } from 'vitest'
+import {
+  formatWorkspaceReferencePrompt,
+  useWorkspaceChatContextStore,
+} from './workspaceChatContextStore'
+
+const initialState = useWorkspaceChatContextStore.getInitialState()
+
+describe('workspaceChatContextStore', () => {
+  beforeEach(() => {
+    useWorkspaceChatContextStore.setState(initialState, true)
+  })
+
+  it('deduplicates file references per session', () => {
+    const store = useWorkspaceChatContextStore.getState()
+
+    store.addReference('session-1', {
+      kind: 'file',
+      path: 'src/App.tsx',
+      absolutePath: '/repo/src/App.tsx',
+      name: 'App.tsx',
+    })
+    store.addReference('session-1', {
+      kind: 'file',
+      path: 'src/App.tsx',
+      absolutePath: '/repo/src/App.tsx',
+      name: 'App.tsx',
+    })
+
+    expect(useWorkspaceChatContextStore.getState().referencesBySession['session-1']).toHaveLength(1)
+  })
+
+  it('formats line comments into the request prompt', () => {
+    const prompt = formatWorkspaceReferencePrompt([
+      {
+        id: 'ref-1',
+        kind: 'code-comment',
+        path: 'src/App.tsx',
+        absolutePath: '/repo/src/App.tsx',
+        name: 'App.tsx',
+        lineStart: 12,
+        lineEnd: 12,
+        note: 'Use a clearer name',
+        quote: 'const value = 1',
+      },
+    ])
+
+    expect(prompt).toContain('Notes for attached workspace files:')
+    expect(prompt).toContain('- src/App.tsx:L12')
+    expect(prompt).toContain('Comment: Use a clearer name')
+    expect(prompt).toContain('Selected code: const value = 1')
+    expect(prompt).not.toContain('Use the Read tool')
+    expect(prompt).not.toContain('Path: /repo/src/App.tsx')
+  })
+
+  it('does not add prompt text for plain file attachments', () => {
+    const prompt = formatWorkspaceReferencePrompt([
+      {
+        id: 'ref-1',
+        kind: 'file',
+        path: 'src/App.tsx',
+        absolutePath: '/repo/src/App.tsx',
+        name: 'App.tsx',
+      },
+    ])
+
+    expect(prompt).toBe('')
+  })
+})

desktop/src/stores/workspaceChatContextStore.ts

@@ -0,0 +1,118 @@
+import { create } from 'zustand'
+
+export type WorkspaceChatReferenceKind = 'file' | 'code-comment'
+
+export type WorkspaceChatReference = {
+  id: string
+  kind: WorkspaceChatReferenceKind
+  path: string
+  absolutePath?: string
+  name: string
+  lineStart?: number
+  lineEnd?: number
+  note?: string
+  quote?: string
+}
+
+type WorkspaceChatContextStore = {
+  referencesBySession: Record<string, WorkspaceChatReference[] | undefined>
+  addReference: (
+    sessionId: string,
+    reference: Omit<WorkspaceChatReference, 'id'> & { id?: string },
+  ) => void
+  removeReference: (sessionId: string, referenceId: string) => void
+  clearReferences: (sessionId: string) => void
+  clearSession: (sessionId: string) => void
+}
+
+function makeReferenceId(reference: Omit<WorkspaceChatReference, 'id'>) {
+  const linePart = reference.lineStart
+    ? `${reference.lineStart}-${reference.lineEnd ?? reference.lineStart}`
+    : 'file'
+  const notePart = reference.note ? reference.note.slice(0, 48) : ''
+  return `${reference.kind}:${reference.path}:${linePart}:${notePart}`
+}
+
+function getReferenceDedupKey(reference: WorkspaceChatReference) {
+  if (reference.kind === 'file') return `${reference.kind}:${reference.path}`
+  return `${reference.kind}:${reference.path}:${reference.lineStart ?? ''}:${reference.lineEnd ?? ''}:${reference.note ?? ''}`
+}
+
+export function formatWorkspaceReferenceLocation(reference: WorkspaceChatReference) {
+  if (!reference.lineStart) return reference.path
+  const lineEnd = reference.lineEnd && reference.lineEnd !== reference.lineStart
+    ? `-L${reference.lineEnd}`
+    : ''
+  return `${reference.path}:L${reference.lineStart}${lineEnd}`
+}
+
+export function formatWorkspaceReferencePrompt(references: WorkspaceChatReference[]) {
+  const referencesWithContext = references.filter((reference) =>
+    reference.kind === 'code-comment' ||
+    !!reference.lineStart ||
+    !!reference.note?.trim() ||
+    !!reference.quote?.trim(),
+  )
+  if (referencesWithContext.length === 0) return ''
+
+  const lines = [
+    'Notes for attached workspace files:',
+    ...referencesWithContext.map((reference) => {
+      const location = formatWorkspaceReferenceLocation(reference)
+      const parts = [`- ${location}`]
+      if (reference.note?.trim()) parts.push(`Comment: ${reference.note.trim()}`)
+      if (reference.quote?.trim()) parts.push(`Selected code: ${reference.quote.trim()}`)
+      return parts.join('\n  ')
+    }),
+  ]
+
+  return lines.join('\n')
+}
+
+export const useWorkspaceChatContextStore = create<WorkspaceChatContextStore>((set) => ({
+  referencesBySession: {},
+
+  addReference: (sessionId, input) =>
+    set((state) => {
+      const reference: WorkspaceChatReference = {
+        ...input,
+        id: input.id ?? makeReferenceId(input),
+      }
+      const existing = state.referencesBySession[sessionId] ?? []
+      const nextKey = getReferenceDedupKey(reference)
+      const withoutDuplicate = existing.filter((item) => getReferenceDedupKey(item) !== nextKey)
+
+      return {
+        referencesBySession: {
+          ...state.referencesBySession,
+          [sessionId]: [...withoutDuplicate, reference],
+        },
+      }
+    }),
+
+  removeReference: (sessionId, referenceId) =>
+    set((state) => {
+      const existing = state.referencesBySession[sessionId] ?? []
+      return {
+        referencesBySession: {
+          ...state.referencesBySession,
+          [sessionId]: existing.filter((reference) => reference.id !== referenceId),
+        },
+      }
+    }),
+
+  clearReferences: (sessionId) =>
+    set((state) => ({
+      referencesBySession: {
+        ...state.referencesBySession,
+        [sessionId]: [],
+      },
+    })),
+
+  clearSession: (sessionId) =>
+    set((state) => {
+      if (!(sessionId in state.referencesBySession)) return state
+      const { [sessionId]: _removed, ...rest } = state.referencesBySession
+      return { referencesBySession: rest }
+    }),
+}))

desktop/src/stores/workspacePanelStore.test.ts

@@ -0,0 +1,636 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+type HoistedVi = typeof vi & {
+  hoisted?: <T>(factory: () => T) => T
+}
+
+if (typeof (vi as HoistedVi).hoisted !== 'function') {
+  ;(vi as HoistedVi).hoisted = <T>(factory: () => T) => factory()
+}
+
+const mocks = vi.hoisted(() => ({
+  getWorkspaceStatusMock: vi.fn(),
+  getWorkspaceTreeMock: vi.fn(),
+  getWorkspaceFileMock: vi.fn(),
+  getWorkspaceDiffMock: vi.fn(),
+}))
+
+vi.mock('../api/sessions', () => ({
+  sessionsApi: {
+    getWorkspaceStatus: mocks.getWorkspaceStatusMock,
+    getWorkspaceTree: mocks.getWorkspaceTreeMock,
+    getWorkspaceFile: mocks.getWorkspaceFileMock,
+    getWorkspaceDiff: mocks.getWorkspaceDiffMock,
+  },
+}))
+
+import { sessionsApi } from '../api/sessions'
+import {
+  WORKSPACE_PANEL_DEFAULT_WIDTH,
+  WORKSPACE_PANEL_MAX_WIDTH,
+  WORKSPACE_PANEL_MIN_WIDTH,
+  getWorkspacePreviewTabId,
+  useWorkspacePanelStore,
+} from './workspacePanelStore'
+
+function deferred<T>() {
+  let resolve!: (value: T) => void
+  let reject!: (reason?: unknown) => void
+  const promise = new Promise<T>((res, rej) => {
+    resolve = res
+    reject = rej
+  })
+  return { promise, resolve, reject }
+}
+
+describe('workspacePanelStore', () => {
+  const initialState = useWorkspacePanelStore.getInitialState()
+
+  beforeEach(() => {
+    vi.clearAllMocks()
+    useWorkspacePanelStore.setState(initialState, true)
+  })
+
+  afterEach(() => {
+    useWorkspacePanelStore.setState(initialState, true)
+    vi.restoreAllMocks()
+  })
+
+  it('uses hoisted session api mocks', () => {
+    expect(sessionsApi.getWorkspaceStatus).toBe(mocks.getWorkspaceStatusMock)
+    expect(sessionsApi.getWorkspaceTree).toBe(mocks.getWorkspaceTreeMock)
+    expect(sessionsApi.getWorkspaceFile).toBe(mocks.getWorkspaceFileMock)
+    expect(sessionsApi.getWorkspaceDiff).toBe(mocks.getWorkspaceDiffMock)
+  })
+
+  it('keeps panel open state and active view isolated per session', () => {
+    const store = useWorkspacePanelStore.getState()
+
+    expect(store.isPanelOpen('session-a')).toBe(false)
+    expect(store.getActiveView('session-a')).toBe('changed')
+    expect(store.width).toBe(WORKSPACE_PANEL_DEFAULT_WIDTH)
+
+    store.openPanel('session-a')
+    store.setActiveView('session-a', 'all')
+
+    expect(useWorkspacePanelStore.getState().isPanelOpen('session-a')).toBe(true)
+    expect(useWorkspacePanelStore.getState().getActiveView('session-a')).toBe('all')
+    expect(useWorkspacePanelStore.getState().isPanelOpen('session-b')).toBe(false)
+    expect(useWorkspacePanelStore.getState().getActiveView('session-b')).toBe('changed')
+
+    store.togglePanel('session-b')
+    expect(useWorkspacePanelStore.getState().isPanelOpen('session-b')).toBe(true)
+    expect(useWorkspacePanelStore.getState().isPanelOpen('session-a')).toBe(true)
+
+    store.closePanel('session-a')
+    expect(useWorkspacePanelStore.getState().isPanelOpen('session-a')).toBe(false)
+    expect(useWorkspacePanelStore.getState().getActiveView('session-a')).toBe('all')
+
+    store.setWidth(120)
+    expect(useWorkspacePanelStore.getState().width).toBe(WORKSPACE_PANEL_MIN_WIDTH)
+    store.setWidth(1200)
+    expect(useWorkspacePanelStore.getState().width).toBe(WORKSPACE_PANEL_MAX_WIDTH)
+  })
+
+  it('loads workspace status successfully', async () => {
+    mocks.getWorkspaceStatusMock.mockResolvedValue({
+      state: 'ok',
+      workDir: '/repo',
+      repoName: 'repo',
+      branch: 'main',
+      isGitRepo: true,
+      changedFiles: [
+        {
+          path: 'src/a.ts',
+          status: 'modified',
+          additions: 3,
+          deletions: 1,
+        },
+      ],
+    })
+
+    await useWorkspacePanelStore.getState().loadStatus('session-1')
+
+    expect(mocks.getWorkspaceStatusMock).toHaveBeenCalledWith('session-1')
+    expect(useWorkspacePanelStore.getState().statusBySession['session-1']).toMatchObject({
+      branch: 'main',
+      changedFiles: [{ path: 'src/a.ts' }],
+    })
+    expect(useWorkspacePanelStore.getState().loading.statusBySession['session-1']).toBe(false)
+    expect(useWorkspacePanelStore.getState().errors.statusBySession['session-1']).toBeNull()
+  })
+
+  it('defaults an empty changed-files status to the all-files view', async () => {
+    mocks.getWorkspaceStatusMock.mockResolvedValue({
+      state: 'ok',
+      workDir: '/repo',
+      repoName: 'repo',
+      branch: 'main',
+      isGitRepo: true,
+      changedFiles: [],
+    })
+
+    useWorkspacePanelStore.getState().openPanel('session-empty-changes')
+    expect(useWorkspacePanelStore.getState().getActiveView('session-empty-changes')).toBe('changed')
+
+    await useWorkspacePanelStore.getState().loadStatus('session-empty-changes')
+
+    expect(useWorkspacePanelStore.getState().statusBySession['session-empty-changes']?.changedFiles).toEqual([])
+    expect(useWorkspacePanelStore.getState().getActiveView('session-empty-changes')).toBe('all')
+  })
+
+  it('keeps the changed-files view when status contains changes', async () => {
+    mocks.getWorkspaceStatusMock.mockResolvedValue({
+      state: 'ok',
+      workDir: '/repo',
+      repoName: 'repo',
+      branch: 'main',
+      isGitRepo: true,
+      changedFiles: [
+        {
+          path: 'src/app.ts',
+          status: 'modified',
+          additions: 2,
+          deletions: 1,
+        },
+      ],
+    })
+
+    useWorkspacePanelStore.getState().openPanel('session-has-changes')
+    await useWorkspacePanelStore.getState().loadStatus('session-has-changes')
+
+    expect(useWorkspacePanelStore.getState().getActiveView('session-has-changes')).toBe('changed')
+  })
+
+  it('does not override an explicit changed-files selection when status is empty', async () => {
+    mocks.getWorkspaceStatusMock.mockResolvedValue({
+      state: 'ok',
+      workDir: '/repo',
+      repoName: 'repo',
+      branch: 'main',
+      isGitRepo: true,
+      changedFiles: [],
+    })
+
+    useWorkspacePanelStore.getState().openPanel('session-explicit-changed')
+    useWorkspacePanelStore.getState().setActiveView('session-explicit-changed', 'changed')
+    await useWorkspacePanelStore.getState().loadStatus('session-explicit-changed')
+
+    expect(useWorkspacePanelStore.getState().getActiveView('session-explicit-changed')).toBe('changed')
+  })
+
+  it('captures workspace status request errors', async () => {
+    mocks.getWorkspaceStatusMock.mockRejectedValue(new Error('status failed'))
+
+    await useWorkspacePanelStore.getState().loadStatus('session-err')
+
+    expect(useWorkspacePanelStore.getState().statusBySession['session-err']).toBeUndefined()
+    expect(useWorkspacePanelStore.getState().loading.statusBySession['session-err']).toBe(false)
+    expect(useWorkspacePanelStore.getState().errors.statusBySession['session-err']).toBe('status failed')
+  })
+
+  it('lazily loads tree nodes when expanding and reuses cached results', async () => {
+    mocks.getWorkspaceTreeMock.mockResolvedValue({
+      state: 'ok',
+      path: '',
+      entries: [
+        { name: 'src', path: 'src', isDirectory: true },
+        { name: 'README.md', path: 'README.md', isDirectory: false },
+      ],
+    })
+
+    await useWorkspacePanelStore.getState().toggleTreeNode('session-tree', '')
+
+    expect(mocks.getWorkspaceTreeMock).toHaveBeenCalledTimes(1)
+    expect(mocks.getWorkspaceTreeMock).toHaveBeenCalledWith('session-tree', '')
+    expect(useWorkspacePanelStore.getState().expandedPathsBySession['session-tree']).toEqual([''])
+    expect(useWorkspacePanelStore.getState().treeBySessionPath['session-tree']?.['']).toMatchObject({
+      entries: [{ path: 'src' }, { path: 'README.md' }],
+    })
+
+    await useWorkspacePanelStore.getState().toggleTreeNode('session-tree', '')
+    expect(useWorkspacePanelStore.getState().expandedPathsBySession['session-tree']).toEqual([])
+
+    await useWorkspacePanelStore.getState().toggleTreeNode('session-tree', '')
+    expect(mocks.getWorkspaceTreeMock).toHaveBeenCalledTimes(1)
+    expect(useWorkspacePanelStore.getState().expandedPathsBySession['session-tree']).toEqual([''])
+  })
+
+  it('ignores stale tree responses for the same session path', async () => {
+    const first = deferred<{ state: 'ok'; path: string; entries: Array<{ name: string; path: string; isDirectory: boolean }> }>()
+    const second = deferred<{ state: 'ok'; path: string; entries: Array<{ name: string; path: string; isDirectory: boolean }> }>()
+
+    mocks.getWorkspaceTreeMock
+      .mockReturnValueOnce(first.promise)
+      .mockReturnValueOnce(second.promise)
+
+    const firstLoad = useWorkspacePanelStore.getState().loadTree('session-tree-race', 'src')
+    const secondLoad = useWorkspacePanelStore.getState().loadTree('session-tree-race', 'src')
+
+    second.resolve({
+      state: 'ok',
+      path: 'src',
+      entries: [{ name: 'new.ts', path: 'src/new.ts', isDirectory: false }],
+    })
+    await secondLoad
+
+    first.resolve({
+      state: 'ok',
+      path: 'src',
+      entries: [{ name: 'old.ts', path: 'src/old.ts', isDirectory: false }],
+    })
+    await firstLoad
+
+    expect(useWorkspacePanelStore.getState().treeBySessionPath['session-tree-race']?.src?.entries).toEqual([
+      { name: 'new.ts', path: 'src/new.ts', isDirectory: false },
+    ])
+  })
+
+  it('opens preview tabs, supports multiple kinds, and reuses duplicates without persistence', async () => {
+    const storage = typeof globalThis.localStorage === 'undefined' ? null : globalThis.localStorage
+    const setItemSpy = storage ? vi.spyOn(storage, 'setItem') : null
+
+    mocks.getWorkspaceFileMock.mockResolvedValue({
+      state: 'ok',
+      path: 'src/a.ts',
+      content: 'export const a = 1',
+      language: 'typescript',
+      size: 18,
+    })
+    mocks.getWorkspaceDiffMock.mockResolvedValue({
+      state: 'ok',
+      path: 'src/a.ts',
+      diff: '@@ -1 +1 @@',
+    })
+
+    useWorkspacePanelStore.getState().openPanel('session-preview')
+    await useWorkspacePanelStore.getState().openPreview('session-preview', 'src/a.ts', 'file')
+    await useWorkspacePanelStore.getState().openPreview('session-preview', 'src/a.ts', 'diff')
+    await useWorkspacePanelStore.getState().openPreview('session-preview', 'src/a.ts', 'file')
+
+    expect(mocks.getWorkspaceFileMock).toHaveBeenCalledTimes(1)
+    expect(mocks.getWorkspaceDiffMock).toHaveBeenCalledTimes(1)
+
+    const tabs = useWorkspacePanelStore.getState().previewTabsBySession['session-preview']
+    expect(tabs).toBeDefined()
+    expect(tabs).toHaveLength(2)
+    expect(tabs![0]).toMatchObject({
+      id: 'file:src/a.ts',
+      kind: 'file',
+      path: 'src/a.ts',
+      content: 'export const a = 1',
+      language: 'typescript',
+    })
+    expect(tabs![1]).toMatchObject({
+      id: 'diff:src/a.ts',
+      kind: 'diff',
+      path: 'src/a.ts',
+      diff: '@@ -1 +1 @@',
+    })
+    expect(useWorkspacePanelStore.getState().activePreviewTabIdBySession['session-preview']).toBe('file:src/a.ts')
+    if (setItemSpy) {
+      expect(setItemSpy).not.toHaveBeenCalled()
+    } else {
+      expect(storage).toBeNull()
+    }
+  })
+
+  it('closes exact tab id and preserves sibling preview for the same path', async () => {
+    mocks.getWorkspaceFileMock.mockResolvedValue({
+      state: 'ok',
+      path: 'src/a.ts',
+      content: 'export const a = 1',
+      language: 'typescript',
+      size: 18,
+    })
+    mocks.getWorkspaceDiffMock.mockResolvedValue({
+      state: 'ok',
+      path: 'src/a.ts',
+      diff: '@@ -1 +1 @@',
+    })
+
+    await useWorkspacePanelStore.getState().openPreview('session-close-path', 'src/a.ts', 'file')
+    await useWorkspacePanelStore.getState().openPreview('session-close-path', 'src/a.ts', 'diff')
+
+    useWorkspacePanelStore.getState().closePreview('session-close-path', 'diff:src/a.ts')
+
+    expect(useWorkspacePanelStore.getState().previewTabsBySession['session-close-path']).toEqual([
+      expect.objectContaining({ id: 'file:src/a.ts' }),
+    ])
+    expect(useWorkspacePanelStore.getState().activePreviewTabIdBySession['session-close-path']).toBe('file:src/a.ts')
+  })
+
+  it('chooses the next sensible active preview when closing the current tab', async () => {
+    mocks.getWorkspaceFileMock
+      .mockResolvedValueOnce({
+        state: 'ok',
+        path: 'src/a.ts',
+        content: 'a',
+        language: 'typescript',
+        size: 1,
+      })
+      .mockResolvedValueOnce({
+        state: 'ok',
+        path: 'src/b.ts',
+        content: 'b',
+        language: 'typescript',
+        size: 1,
+      })
+      .mockResolvedValueOnce({
+        state: 'ok',
+        path: 'src/c.ts',
+        content: 'c',
+        language: 'typescript',
+        size: 1,
+      })
+
+    await useWorkspacePanelStore.getState().openPreview('session-close', 'src/a.ts', 'file')
+    await useWorkspacePanelStore.getState().openPreview('session-close', 'src/b.ts', 'file')
+    await useWorkspacePanelStore.getState().openPreview('session-close', 'src/c.ts', 'file')
+
+    useWorkspacePanelStore.getState().closePreview('session-close', 'file:src/b.ts')
+
+    expect(useWorkspacePanelStore.getState().previewTabsBySession['session-close']).toMatchObject([
+      { id: 'file:src/a.ts' },
+      { id: 'file:src/c.ts' },
+    ])
+    expect(useWorkspacePanelStore.getState().activePreviewTabIdBySession['session-close']).toBe('file:src/c.ts')
+
+    useWorkspacePanelStore.getState().closePreview('session-close', 'file:src/c.ts')
+    expect(useWorkspacePanelStore.getState().activePreviewTabIdBySession['session-close']).toBe('file:src/a.ts')
+  })
+
+  it('closes preview tabs by context-menu scope', () => {
+    useWorkspacePanelStore.setState((state) => ({
+      ...state,
+      previewTabsBySession: {
+        ...state.previewTabsBySession,
+        'session-preview-scope': [
+          { id: 'file:a.ts', path: 'a.ts', kind: 'file', title: 'a.ts', state: 'ok', language: 'typescript', size: 1 },
+          { id: 'file:b.ts', path: 'b.ts', kind: 'file', title: 'b.ts', state: 'ok', language: 'typescript', size: 1 },
+          { id: 'file:c.ts', path: 'c.ts', kind: 'file', title: 'c.ts', state: 'ok', language: 'typescript', size: 1 },
+          { id: 'file:d.ts', path: 'd.ts', kind: 'file', title: 'd.ts', state: 'ok', language: 'typescript', size: 1 },
+        ],
+      },
+      activePreviewTabIdBySession: {
+        ...state.activePreviewTabIdBySession,
+        'session-preview-scope': 'file:d.ts',
+      },
+      loading: {
+        ...state.loading,
+        previewByTabId: {
+          ...state.loading.previewByTabId,
+          'session-preview-scope::file:c.ts': true,
+          'session-preview-scope::file:d.ts': true,
+        },
+      },
+      errors: {
+        ...state.errors,
+        previewByTabId: {
+          ...state.errors.previewByTabId,
+          'session-preview-scope::file:c.ts': 'loading',
+          'session-preview-scope::file:d.ts': 'loading',
+        },
+      },
+    }))
+
+    useWorkspacePanelStore.getState().closePreviewTabs('session-preview-scope', 'file:b.ts', 'right')
+
+    expect(useWorkspacePanelStore.getState().previewTabsBySession['session-preview-scope']).toMatchObject([
+      { id: 'file:a.ts' },
+      { id: 'file:b.ts' },
+    ])
+    expect(useWorkspacePanelStore.getState().activePreviewTabIdBySession['session-preview-scope']).toBe('file:b.ts')
+    expect(useWorkspacePanelStore.getState().loading.previewByTabId['session-preview-scope::file:c.ts']).toBeUndefined()
+    expect(useWorkspacePanelStore.getState().errors.previewByTabId['session-preview-scope::file:d.ts']).toBeUndefined()
+
+    useWorkspacePanelStore.getState().closePreviewTabs('session-preview-scope', 'file:b.ts', 'others')
+
+    expect(useWorkspacePanelStore.getState().previewTabsBySession['session-preview-scope']).toMatchObject([
+      { id: 'file:b.ts' },
+    ])
+    expect(useWorkspacePanelStore.getState().activePreviewTabIdBySession['session-preview-scope']).toBe('file:b.ts')
+
+    useWorkspacePanelStore.getState().closePreviewTabs('session-preview-scope', 'file:b.ts', 'all')
+
+    expect(useWorkspacePanelStore.getState().previewTabsBySession['session-preview-scope']).toBeUndefined()
+    expect(useWorkspacePanelStore.getState().activePreviewTabIdBySession['session-preview-scope']).toBeNull()
+  })
+
+  it('ignores stale status responses for the same session', async () => {
+    const first = deferred<{
+      state: 'ok'
+      workDir: string
+      repoName: string | null
+      branch: string | null
+      isGitRepo: boolean
+      changedFiles: []
+      error?: string
+    }>()
+    const second = deferred<{
+      state: 'ok'
+      workDir: string
+      repoName: string | null
+      branch: string | null
+      isGitRepo: boolean
+      changedFiles: []
+      error?: string
+    }>()
+
+    mocks.getWorkspaceStatusMock
+      .mockReturnValueOnce(first.promise)
+      .mockReturnValueOnce(second.promise)
+
+    const firstLoad = useWorkspacePanelStore.getState().loadStatus('session-race')
+    const secondLoad = useWorkspacePanelStore.getState().loadStatus('session-race')
+
+    second.resolve({
+      state: 'ok',
+      workDir: '/repo',
+      repoName: 'repo',
+      branch: 'new',
+      isGitRepo: true,
+      changedFiles: [],
+    })
+    await secondLoad
+
+    first.resolve({
+      state: 'ok',
+      workDir: '/repo',
+      repoName: 'repo',
+      branch: 'old',
+      isGitRepo: true,
+      changedFiles: [],
+    })
+    await firstLoad
+
+    expect(useWorkspacePanelStore.getState().statusBySession['session-race']?.branch).toBe('new')
+  })
+
+  it('ignores stale preview responses after close and reopen', async () => {
+    const first = deferred<{ state: 'ok'; path: string; content: string; language: string; size: number }>()
+    const second = deferred<{ state: 'ok'; path: string; content: string; language: string; size: number }>()
+
+    mocks.getWorkspaceFileMock
+      .mockReturnValueOnce(first.promise)
+      .mockReturnValueOnce(second.promise)
+
+    const firstOpen = useWorkspacePanelStore.getState().openPreview('session-preview-race', 'src/a.ts', 'file')
+    useWorkspacePanelStore.getState().closePreview('session-preview-race', 'file:src/a.ts')
+    const secondOpen = useWorkspacePanelStore.getState().openPreview('session-preview-race', 'src/a.ts', 'file')
+
+    second.resolve({
+      state: 'ok',
+      path: 'src/a.ts',
+      content: 'new',
+      language: 'typescript',
+      size: 3,
+    })
+    await secondOpen
+
+    first.resolve({
+      state: 'ok',
+      path: 'src/a.ts',
+      content: 'old',
+      language: 'typescript',
+      size: 3,
+    })
+    await firstOpen
+
+    expect(useWorkspacePanelStore.getState().previewTabsBySession['session-preview-race']).toEqual([
+      expect.objectContaining({ id: 'file:src/a.ts', content: 'new' }),
+    ])
+  })
+
+  it('does not recreate loading or error state when a loading preview is closed before completion', async () => {
+    const pending = deferred<{ state: 'ok'; path: string; diff: string }>()
+    const tabId = getWorkspacePreviewTabId('src/a.ts', 'diff')
+    const previewKey = `session-preview-close::${tabId}`
+
+    mocks.getWorkspaceDiffMock.mockReturnValueOnce(pending.promise)
+
+    const openPromise = useWorkspacePanelStore.getState().openPreview('session-preview-close', 'src/a.ts', 'diff')
+    useWorkspacePanelStore.getState().closePreview('session-preview-close', tabId)
+
+    pending.resolve({
+      state: 'ok',
+      path: 'src/a.ts',
+      diff: '@@ -1 +1 @@',
+    })
+    await openPromise
+
+    expect(useWorkspacePanelStore.getState().previewTabsBySession['session-preview-close']).toBeUndefined()
+    expect(useWorkspacePanelStore.getState().activePreviewTabIdBySession['session-preview-close']).toBeNull()
+    expect(useWorkspacePanelStore.getState().loading.previewByTabId[previewKey]).toBeUndefined()
+    expect(useWorkspacePanelStore.getState().errors.previewByTabId[previewKey]).toBeUndefined()
+  })
+
+  it('clears session UI and cached data for clearSession and resetSessionUi', () => {
+    useWorkspacePanelStore.setState((state) => ({
+      ...state,
+      panelBySession: {
+        'session-clear': { isOpen: true, activeView: 'all' },
+        'session-reset': { isOpen: true, activeView: 'all' },
+      },
+      statusBySession: {
+        'session-clear': {
+          state: 'ok',
+          workDir: '/repo',
+          repoName: 'repo',
+          branch: 'main',
+          isGitRepo: true,
+          changedFiles: [],
+        },
+        'session-reset': {
+          state: 'ok',
+          workDir: '/repo',
+          repoName: 'repo',
+          branch: 'main',
+          isGitRepo: true,
+          changedFiles: [],
+        },
+      },
+      expandedPathsBySession: {
+        'session-clear': ['src'],
+        'session-reset': ['src'],
+      },
+      treeBySessionPath: {
+        'session-clear': {
+          src: { state: 'ok', path: 'src', entries: [] },
+        },
+        'session-reset': {
+          src: { state: 'ok', path: 'src', entries: [] },
+        },
+      },
+      previewTabsBySession: {
+        'session-clear': [
+          { id: 'file:src/a.ts', path: 'src/a.ts', kind: 'file', title: 'a.ts' },
+        ],
+        'session-reset': [
+          { id: 'file:src/b.ts', path: 'src/b.ts', kind: 'file', title: 'b.ts' },
+        ],
+      },
+      activePreviewTabIdBySession: {
+        'session-clear': 'file:src/a.ts',
+        'session-reset': 'file:src/b.ts',
+      },
+      loading: {
+        statusBySession: {
+          'session-clear': true,
+          'session-reset': true,
+        },
+        treeBySessionPath: {
+          'session-clear::src': true,
+          'session-reset::src': true,
+        },
+        previewByTabId: {
+          'session-clear::file:src/a.ts': true,
+          'session-reset::file:src/b.ts': true,
+        },
+      },
+      errors: {
+        statusBySession: {
+          'session-clear': 'bad',
+          'session-reset': 'bad',
+        },
+        treeBySessionPath: {
+          'session-clear::src': 'bad',
+          'session-reset::src': 'bad',
+        },
+        previewByTabId: {
+          'session-clear::file:src/a.ts': 'bad',
+          'session-reset::file:src/b.ts': 'bad',
+        },
+      },
+    }))
+
+    useWorkspacePanelStore.getState().clearSession('session-clear')
+    useWorkspacePanelStore.getState().resetSessionUi('session-reset')
+
+    const state = useWorkspacePanelStore.getState()
+    expect(state.panelBySession['session-clear']).toBeUndefined()
+    expect(state.panelBySession['session-reset']).toBeUndefined()
+    expect(state.statusBySession['session-clear']).toBeUndefined()
+    expect(state.statusBySession['session-reset']).toBeUndefined()
+    expect(state.expandedPathsBySession['session-clear']).toBeUndefined()
+    expect(state.expandedPathsBySession['session-reset']).toBeUndefined()
+    expect(state.treeBySessionPath['session-clear']).toBeUndefined()
+    expect(state.treeBySessionPath['session-reset']).toBeUndefined()
+    expect(state.previewTabsBySession['session-clear']).toBeUndefined()
+    expect(state.previewTabsBySession['session-reset']).toBeUndefined()
+    expect(state.activePreviewTabIdBySession['session-clear']).toBeUndefined()
+    expect(state.activePreviewTabIdBySession['session-reset']).toBeUndefined()
+    expect(state.loading.statusBySession['session-clear']).toBeUndefined()
+    expect(state.loading.statusBySession['session-reset']).toBeUndefined()
+    expect(state.loading.treeBySessionPath['session-clear::src']).toBeUndefined()
+    expect(state.loading.treeBySessionPath['session-reset::src']).toBeUndefined()
+    expect(state.loading.previewByTabId['session-clear::file:src/a.ts']).toBeUndefined()
+    expect(state.loading.previewByTabId['session-reset::file:src/b.ts']).toBeUndefined()
+    expect(state.errors.statusBySession['session-clear']).toBeUndefined()
+    expect(state.errors.statusBySession['session-reset']).toBeUndefined()
+    expect(state.errors.treeBySessionPath['session-clear::src']).toBeUndefined()
+    expect(state.errors.treeBySessionPath['session-reset::src']).toBeUndefined()
+    expect(state.errors.previewByTabId['session-clear::file:src/a.ts']).toBeUndefined()
+    expect(state.errors.previewByTabId['session-reset::file:src/b.ts']).toBeUndefined()
+  })
+})

desktop/src/stores/workspacePanelStore.ts

@@ -0,0 +1,716 @@
+import { create } from 'zustand'
+import {
+  sessionsApi,
+  type WorkspaceDiffResult,
+  type WorkspaceReadFileResult,
+  type WorkspaceStatusResult,
+  type WorkspaceTreeResult,
+} from '../api/sessions'
+
+export const WORKSPACE_PANEL_DEFAULT_WIDTH = 860
+export const WORKSPACE_PANEL_MIN_WIDTH = 640
+export const WORKSPACE_PANEL_MAX_WIDTH = 1120
+
+export type WorkspacePanelView = 'changed' | 'all'
+export type WorkspacePreviewKind = 'file' | 'diff'
+export type WorkspacePreviewCloseScope = 'current' | 'others' | 'left' | 'right' | 'all'
+export type WorkspacePreviewState =
+  | 'loading'
+  | WorkspaceReadFileResult['state']
+  | WorkspaceDiffResult['state']
+
+export type WorkspacePreviewTab = {
+  id: string
+  path: string
+  kind: WorkspacePreviewKind
+  title: string
+  language?: string
+  content?: string
+  dataUrl?: string
+  mimeType?: string
+  previewType?: 'text' | 'image'
+  diff?: string
+  state?: WorkspacePreviewState
+  error?: string
+  size?: number
+}
+
+export type WorkspacePanelSessionState = {
+  isOpen: boolean
+  activeView: WorkspacePanelView
+  hasUserSelectedView?: boolean
+}
+
+type WorkspacePanelLoadingState = {
+  statusBySession: Record<string, boolean | undefined>
+  treeBySessionPath: Record<string, boolean | undefined>
+  previewByTabId: Record<string, boolean | undefined>
+}
+
+type WorkspacePanelErrorState = {
+  statusBySession: Record<string, string | null | undefined>
+  treeBySessionPath: Record<string, string | null | undefined>
+  previewByTabId: Record<string, string | null | undefined>
+}
+
+type WorkspacePanelStore = {
+  panelBySession: Record<string, WorkspacePanelSessionState | undefined>
+  width: number
+  statusBySession: Record<string, WorkspaceStatusResult | undefined>
+  expandedPathsBySession: Record<string, string[] | undefined>
+  treeBySessionPath: Record<string, Record<string, WorkspaceTreeResult | undefined> | undefined>
+  previewTabsBySession: Record<string, WorkspacePreviewTab[] | undefined>
+  activePreviewTabIdBySession: Record<string, string | null | undefined>
+  loading: WorkspacePanelLoadingState
+  errors: WorkspacePanelErrorState
+
+  isPanelOpen: (sessionId: string) => boolean
+  getActiveView: (sessionId: string) => WorkspacePanelView
+  openPanel: (sessionId: string) => void
+  closePanel: (sessionId: string) => void
+  togglePanel: (sessionId: string) => void
+  setWidth: (width: number) => void
+  setActiveView: (sessionId: string, view: WorkspacePanelView) => void
+  loadStatus: (sessionId: string) => Promise<void>
+  loadTree: (sessionId: string, path?: string) => Promise<void>
+  toggleTreeNode: (sessionId: string, path: string) => Promise<void>
+  openPreview: (sessionId: string, path: string, kind: WorkspacePreviewKind) => Promise<void>
+  closePreview: (sessionId: string, tabId: string) => void
+  closePreviewTabs: (sessionId: string, tabId: string, scope: WorkspacePreviewCloseScope) => void
+  clearSession: (sessionId: string) => void
+  resetSessionUi: (sessionId: string) => void
+}
+
+const DEFAULT_PANEL_STATE: WorkspacePanelSessionState = {
+  isOpen: false,
+  activeView: 'changed',
+}
+
+const statusRequestIds = new Map<string, number>()
+const treeRequestIds = new Map<string, number>()
+const previewRequestIds = new Map<string, number>()
+
+function nextRequestId(store: Map<string, number>, key: string) {
+  const requestId = (store.get(key) ?? 0) + 1
+  store.set(key, requestId)
+  return requestId
+}
+
+function invalidateRequest(store: Map<string, number>, key: string) {
+  store.set(key, (store.get(key) ?? 0) + 1)
+}
+
+function isLatestRequest(store: Map<string, number>, key: string, requestId: number) {
+  return store.get(key) === requestId
+}
+
+export function clampWorkspacePanelWidth(width: number) {
+  if (!Number.isFinite(width)) return WORKSPACE_PANEL_DEFAULT_WIDTH
+  const rounded = Math.round(width)
+  return Math.min(WORKSPACE_PANEL_MAX_WIDTH, Math.max(WORKSPACE_PANEL_MIN_WIDTH, rounded))
+}
+
+function getSessionPanelState(
+  panelBySession: Record<string, WorkspacePanelSessionState | undefined>,
+  sessionId: string,
+) {
+  return panelBySession[sessionId] ?? DEFAULT_PANEL_STATE
+}
+
+function makeTreeKey(sessionId: string, path: string) {
+  return `${sessionId}::${path}`
+}
+
+export function getWorkspacePreviewTabId(path: string, kind: WorkspacePreviewKind) {
+  return `${kind}:${path}`
+}
+
+function makePreviewKey(sessionId: string, tabId: string) {
+  return `${sessionId}::${tabId}`
+}
+
+function getPathTitle(path: string) {
+  if (!path) return 'Workspace'
+  const segments = path.split('/').filter(Boolean)
+  return segments[segments.length - 1] ?? path
+}
+
+function stripSessionKeys<T>(record: Record<string, T>, sessionId: string) {
+  const prefix = `${sessionId}::`
+  return Object.fromEntries(
+    Object.entries(record).filter(([key]) => !key.startsWith(prefix)),
+  ) as Record<string, T>
+}
+
+function removeRecordKey<T>(record: Record<string, T>, key: string) {
+  if (!(key in record)) return record
+  const { [key]: _removed, ...rest } = record
+  return rest
+}
+
+function removeRecordKeys<T>(record: Record<string, T>, keys: string[]) {
+  let next = record
+  for (const key of keys) {
+    next = removeRecordKey(next, key)
+  }
+  return next
+}
+
+function invalidateSessionScopedRequests(store: Map<string, number>, sessionId: string) {
+  const prefix = `${sessionId}::`
+  for (const key of store.keys()) {
+    if (key.startsWith(prefix)) {
+      invalidateRequest(store, key)
+    }
+  }
+}
+
+function upsertPreviewTab(
+  tabs: WorkspacePreviewTab[],
+  tabId: string,
+  update: WorkspacePreviewTab | ((current: WorkspacePreviewTab) => WorkspacePreviewTab),
+) {
+  const index = tabs.findIndex((tab) => tab.id === tabId)
+  if (index < 0) return tabs
+
+  const current = tabs[index]!
+  const next = typeof update === 'function' ? update(current) : update
+  const nextTabs = [...tabs]
+  nextTabs[index] = next
+  return nextTabs
+}
+
+export const useWorkspacePanelStore = create<WorkspacePanelStore>((set, get) => ({
+  panelBySession: {},
+  width: WORKSPACE_PANEL_DEFAULT_WIDTH,
+  statusBySession: {},
+  expandedPathsBySession: {},
+  treeBySessionPath: {},
+  previewTabsBySession: {},
+  activePreviewTabIdBySession: {},
+  loading: {
+    statusBySession: {},
+    treeBySessionPath: {},
+    previewByTabId: {},
+  },
+  errors: {
+    statusBySession: {},
+    treeBySessionPath: {},
+    previewByTabId: {},
+  },
+
+  isPanelOpen: (sessionId) => getSessionPanelState(get().panelBySession, sessionId).isOpen,
+  getActiveView: (sessionId) => getSessionPanelState(get().panelBySession, sessionId).activeView,
+
+  openPanel: (sessionId) =>
+    set((state) => ({
+      panelBySession: {
+        ...state.panelBySession,
+        [sessionId]: {
+          ...getSessionPanelState(state.panelBySession, sessionId),
+          isOpen: true,
+        },
+      },
+    })),
+
+  closePanel: (sessionId) =>
+    set((state) => ({
+      panelBySession: {
+        ...state.panelBySession,
+        [sessionId]: {
+          ...getSessionPanelState(state.panelBySession, sessionId),
+          isOpen: false,
+        },
+      },
+    })),
+
+  togglePanel: (sessionId) =>
+    set((state) => {
+      const panel = getSessionPanelState(state.panelBySession, sessionId)
+      return {
+        panelBySession: {
+          ...state.panelBySession,
+          [sessionId]: {
+            ...panel,
+            isOpen: !panel.isOpen,
+          },
+        },
+      }
+    }),
+
+  setWidth: (width) => set({ width: clampWorkspacePanelWidth(width) }),
+
+  setActiveView: (sessionId, view) =>
+    set((state) => ({
+      panelBySession: {
+        ...state.panelBySession,
+        [sessionId]: {
+          ...getSessionPanelState(state.panelBySession, sessionId),
+          activeView: view,
+          hasUserSelectedView: true,
+        },
+      },
+    })),
+
+  loadStatus: async (sessionId) => {
+    const requestId = nextRequestId(statusRequestIds, sessionId)
+
+    set((state) => ({
+      loading: {
+        ...state.loading,
+        statusBySession: {
+          ...state.loading.statusBySession,
+          [sessionId]: true,
+        },
+      },
+      errors: {
+        ...state.errors,
+        statusBySession: {
+          ...state.errors.statusBySession,
+          [sessionId]: null,
+        },
+      },
+    }))
+
+    try {
+      const result = await sessionsApi.getWorkspaceStatus(sessionId)
+      if (!isLatestRequest(statusRequestIds, sessionId, requestId)) return
+
+      set((state) => {
+        const panel = getSessionPanelState(state.panelBySession, sessionId)
+        const shouldDefaultToAllFiles =
+          !panel.hasUserSelectedView
+          && panel.activeView === 'changed'
+          && result.state === 'ok'
+          && result.changedFiles.length === 0
+
+        return {
+          panelBySession: {
+            ...state.panelBySession,
+            [sessionId]: {
+              ...panel,
+              activeView: shouldDefaultToAllFiles ? 'all' : panel.activeView,
+            },
+          },
+          statusBySession: {
+            ...state.statusBySession,
+            [sessionId]: result,
+          },
+          loading: {
+            ...state.loading,
+            statusBySession: {
+              ...state.loading.statusBySession,
+              [sessionId]: false,
+            },
+          },
+          errors: {
+            ...state.errors,
+            statusBySession: {
+              ...state.errors.statusBySession,
+              [sessionId]: result.error ?? null,
+            },
+          },
+        }
+      })
+    } catch (error) {
+      if (!isLatestRequest(statusRequestIds, sessionId, requestId)) return
+
+      set((state) => ({
+        loading: {
+          ...state.loading,
+          statusBySession: {
+            ...state.loading.statusBySession,
+            [sessionId]: false,
+          },
+        },
+        errors: {
+          ...state.errors,
+          statusBySession: {
+            ...state.errors.statusBySession,
+            [sessionId]: error instanceof Error ? error.message : 'Failed to load workspace status',
+          },
+        },
+      }))
+    }
+  },
+
+  loadTree: async (sessionId, path = '') => {
+    const treeKey = makeTreeKey(sessionId, path)
+    const requestId = nextRequestId(treeRequestIds, treeKey)
+
+    set((state) => ({
+      loading: {
+        ...state.loading,
+        treeBySessionPath: {
+          ...state.loading.treeBySessionPath,
+          [treeKey]: true,
+        },
+      },
+      errors: {
+        ...state.errors,
+        treeBySessionPath: {
+          ...state.errors.treeBySessionPath,
+          [treeKey]: null,
+        },
+      },
+    }))
+
+    try {
+      const result = await sessionsApi.getWorkspaceTree(sessionId, path)
+      if (!isLatestRequest(treeRequestIds, treeKey, requestId)) return
+
+      set((state) => ({
+        treeBySessionPath: {
+          ...state.treeBySessionPath,
+          [sessionId]: {
+            ...state.treeBySessionPath[sessionId],
+            [path]: result,
+          },
+        },
+        loading: {
+          ...state.loading,
+          treeBySessionPath: {
+            ...state.loading.treeBySessionPath,
+            [treeKey]: false,
+          },
+        },
+        errors: {
+          ...state.errors,
+          treeBySessionPath: {
+            ...state.errors.treeBySessionPath,
+            [treeKey]: result.error ?? null,
+          },
+        },
+      }))
+    } catch (error) {
+      if (!isLatestRequest(treeRequestIds, treeKey, requestId)) return
+
+      set((state) => ({
+        loading: {
+          ...state.loading,
+          treeBySessionPath: {
+            ...state.loading.treeBySessionPath,
+            [treeKey]: false,
+          },
+        },
+        errors: {
+          ...state.errors,
+          treeBySessionPath: {
+            ...state.errors.treeBySessionPath,
+            [treeKey]: error instanceof Error ? error.message : 'Failed to load workspace tree',
+          },
+        },
+      }))
+    }
+  },
+
+  toggleTreeNode: async (sessionId, path) => {
+    let shouldLoad = false
+
+    set((state) => {
+      const expanded = new Set(state.expandedPathsBySession[sessionId] ?? [])
+      if (expanded.has(path)) {
+        expanded.delete(path)
+      } else {
+        expanded.add(path)
+        if (!state.treeBySessionPath[sessionId]?.[path]) {
+          shouldLoad = true
+        }
+      }
+
+      return {
+        expandedPathsBySession: {
+          ...state.expandedPathsBySession,
+          [sessionId]: [...expanded],
+        },
+      }
+    })
+
+    if (shouldLoad) {
+      await get().loadTree(sessionId, path)
+    }
+  },
+
+  openPreview: async (sessionId, path, kind) => {
+    const tabId = getWorkspacePreviewTabId(path, kind)
+    const requestKey = makePreviewKey(sessionId, tabId)
+    const existing = get().previewTabsBySession[sessionId]?.find((tab) => tab.id === tabId)
+
+    if (existing) {
+      set((state) => ({
+        activePreviewTabIdBySession: {
+          ...state.activePreviewTabIdBySession,
+          [sessionId]: tabId,
+        },
+      }))
+      return
+    }
+
+    const requestId = nextRequestId(previewRequestIds, requestKey)
+    const baseTab: WorkspacePreviewTab = {
+      id: tabId,
+      path,
+      kind,
+      title: getPathTitle(path),
+      state: 'loading',
+    }
+
+    set((state) => ({
+      previewTabsBySession: {
+        ...state.previewTabsBySession,
+        [sessionId]: [...(state.previewTabsBySession[sessionId] ?? []), baseTab],
+      },
+      activePreviewTabIdBySession: {
+        ...state.activePreviewTabIdBySession,
+        [sessionId]: tabId,
+      },
+      loading: {
+        ...state.loading,
+        previewByTabId: {
+          ...state.loading.previewByTabId,
+          [requestKey]: true,
+        },
+      },
+      errors: {
+        ...state.errors,
+        previewByTabId: {
+          ...state.errors.previewByTabId,
+          [requestKey]: null,
+        },
+      },
+    }))
+
+    try {
+      if (kind === 'diff') {
+        const result = await sessionsApi.getWorkspaceDiff(sessionId, path)
+        if (!isLatestRequest(previewRequestIds, requestKey, requestId)) return
+        if (!get().previewTabsBySession[sessionId]?.some((tab) => tab.id === tabId)) return
+
+        set((state) => {
+          const tabs = state.previewTabsBySession[sessionId] ?? []
+          return {
+            previewTabsBySession: {
+              ...state.previewTabsBySession,
+              [sessionId]: upsertPreviewTab(tabs, tabId, (current) => ({
+                ...current,
+                diff: result.diff ?? '',
+                content: undefined,
+                language: undefined,
+                size: undefined,
+                state: result.state,
+                error: result.error,
+              })),
+            },
+            loading: {
+              ...state.loading,
+              previewByTabId: {
+                ...state.loading.previewByTabId,
+                [requestKey]: false,
+              },
+            },
+            errors: {
+              ...state.errors,
+              previewByTabId: {
+                ...state.errors.previewByTabId,
+                [requestKey]: result.error ?? null,
+              },
+            },
+          }
+        })
+        return
+      }
+
+      const result = await sessionsApi.getWorkspaceFile(sessionId, path)
+      if (!isLatestRequest(previewRequestIds, requestKey, requestId)) return
+      if (!get().previewTabsBySession[sessionId]?.some((tab) => tab.id === tabId)) return
+
+      set((state) => {
+        const tabs = state.previewTabsBySession[sessionId] ?? []
+        return {
+          previewTabsBySession: {
+            ...state.previewTabsBySession,
+            [sessionId]: upsertPreviewTab(tabs, tabId, (current) => ({
+                ...current,
+                content: result.content,
+                dataUrl: result.dataUrl,
+                mimeType: result.mimeType,
+                previewType: result.previewType ?? 'text',
+                diff: undefined,
+                language: result.language,
+              size: result.size,
+              state: result.state,
+              error: result.error,
+            })),
+          },
+          loading: {
+            ...state.loading,
+            previewByTabId: {
+              ...state.loading.previewByTabId,
+              [requestKey]: false,
+            },
+          },
+          errors: {
+            ...state.errors,
+            previewByTabId: {
+              ...state.errors.previewByTabId,
+              [requestKey]: result.error ?? null,
+            },
+          },
+        }
+      })
+    } catch (error) {
+      if (!isLatestRequest(previewRequestIds, requestKey, requestId)) return
+      if (!get().previewTabsBySession[sessionId]?.some((tab) => tab.id === tabId)) return
+
+      set((state) => {
+        const tabs = state.previewTabsBySession[sessionId] ?? []
+        const message = error instanceof Error ? error.message : 'Failed to load workspace preview'
+
+        return {
+          previewTabsBySession: {
+            ...state.previewTabsBySession,
+            [sessionId]: upsertPreviewTab(tabs, tabId, (current) => ({
+              ...current,
+              state: 'error',
+              error: message,
+            })),
+          },
+          loading: {
+            ...state.loading,
+            previewByTabId: {
+              ...state.loading.previewByTabId,
+              [requestKey]: false,
+            },
+          },
+          errors: {
+            ...state.errors,
+            previewByTabId: {
+              ...state.errors.previewByTabId,
+              [requestKey]: message,
+            },
+          },
+        }
+      })
+    }
+  },
+
+  closePreview: (sessionId, tabId) => {
+    get().closePreviewTabs(sessionId, tabId, 'current')
+  },
+
+  closePreviewTabs: (sessionId, tabId, scope) => {
+    set((state) => {
+      const tabs = state.previewTabsBySession[sessionId] ?? []
+      const index = tabs.findIndex((tab) => tab.id === tabId)
+      if (index < 0) {
+        const requestKey = makePreviewKey(sessionId, tabId)
+        invalidateRequest(previewRequestIds, requestKey)
+        return {
+          loading: {
+            ...state.loading,
+            previewByTabId: removeRecordKey(state.loading.previewByTabId, requestKey),
+          },
+          errors: {
+            ...state.errors,
+            previewByTabId: removeRecordKey(state.errors.previewByTabId, requestKey),
+          },
+        }
+      }
+
+      let nextTabs: WorkspacePreviewTab[]
+      switch (scope) {
+        case 'others':
+          nextTabs = [tabs[index]!]
+          break
+        case 'left':
+          nextTabs = tabs.slice(index)
+          break
+        case 'right':
+          nextTabs = tabs.slice(0, index + 1)
+          break
+        case 'all':
+          nextTabs = []
+          break
+        case 'current':
+        default:
+          nextTabs = tabs.filter((tab) => tab.id !== tabId)
+          break
+      }
+
+      const nextTabIds = new Set(nextTabs.map((tab) => tab.id))
+      const closingTabIds = tabs.map((tab) => tab.id).filter((id) => !nextTabIds.has(id))
+      const requestKeys = closingTabIds.map((id) => makePreviewKey(sessionId, id))
+      for (const key of requestKeys) {
+        invalidateRequest(previewRequestIds, key)
+      }
+
+      const activeTabId = state.activePreviewTabIdBySession[sessionId] ?? null
+
+      let nextActiveTabId = activeTabId
+      if (scope === 'all' || nextTabs.length === 0) {
+        nextActiveTabId = null
+      } else if (!activeTabId || !nextTabIds.has(activeTabId)) {
+        const targetTab = nextTabs.find((tab) => tab.id === tabId)
+        nextActiveTabId = targetTab?.id ?? nextTabs[Math.min(index, nextTabs.length - 1)]?.id ?? null
+      } else if (scope === 'others') {
+        nextActiveTabId = tabId
+      } else if (activeTabId === tabId && scope === 'current') {
+        if (nextTabs.length === 0) {
+          nextActiveTabId = null
+        } else if (index >= nextTabs.length) {
+          nextActiveTabId = nextTabs[nextTabs.length - 1]!.id
+        } else {
+          nextActiveTabId = nextTabs[index]!.id
+        }
+      }
+
+      return {
+        previewTabsBySession: {
+          ...state.previewTabsBySession,
+          [sessionId]: nextTabs.length > 0 ? nextTabs : undefined,
+        },
+        activePreviewTabIdBySession: {
+          ...state.activePreviewTabIdBySession,
+          [sessionId]: nextActiveTabId,
+        },
+        loading: {
+          ...state.loading,
+          previewByTabId: removeRecordKeys(state.loading.previewByTabId, requestKeys),
+        },
+        errors: {
+          ...state.errors,
+          previewByTabId: removeRecordKeys(state.errors.previewByTabId, requestKeys),
+        },
+      }
+    })
+  },
+
+  clearSession: (sessionId) => {
+    invalidateRequest(statusRequestIds, sessionId)
+    invalidateSessionScopedRequests(treeRequestIds, sessionId)
+    invalidateSessionScopedRequests(previewRequestIds, sessionId)
+
+    set((state) => ({
+      panelBySession: removeRecordKey(state.panelBySession, sessionId),
+      statusBySession: removeRecordKey(state.statusBySession, sessionId),
+      expandedPathsBySession: removeRecordKey(state.expandedPathsBySession, sessionId),
+      treeBySessionPath: removeRecordKey(state.treeBySessionPath, sessionId),
+      previewTabsBySession: removeRecordKey(state.previewTabsBySession, sessionId),
+      activePreviewTabIdBySession: removeRecordKey(state.activePreviewTabIdBySession, sessionId),
+      loading: {
+        statusBySession: removeRecordKey(state.loading.statusBySession, sessionId),
+        treeBySessionPath: stripSessionKeys(state.loading.treeBySessionPath, sessionId),
+        previewByTabId: stripSessionKeys(state.loading.previewByTabId, sessionId),
+      },
+      errors: {
+        statusBySession: removeRecordKey(state.errors.statusBySession, sessionId),
+        treeBySessionPath: stripSessionKeys(state.errors.treeBySessionPath, sessionId),
+        previewByTabId: stripSessionKeys(state.errors.previewByTabId, sessionId),
+      },
+    }))
+  },
+
+  resetSessionUi: (sessionId) => {
+    get().clearSession(sessionId)
+  },
+}))

desktop/src/types/chat.ts

@@ -31,13 +31,22 @@ export type AttachmentRef = {
   path?: string
   data?: string
   mimeType?: string
+  lineStart?: number
+  lineEnd?: number
+  note?: string
+  quote?: string
 }
 
 export type UIAttachment = {
   type: 'file' | 'image'
   name: string
+  path?: string
   data?: string
   mimeType?: string
+  lineStart?: number
+  lineEnd?: number
+  note?: string
+  quote?: string
 }
 
 // ─── Server → Client ──────────────────────────────────────────────
@@ -157,7 +166,7 @@ export type TaskSummaryItem = {
 }
 
 export type UIMessage =
-  | { id: string; type: 'user_text'; content: string; timestamp: number; attachments?: UIAttachment[]; pending?: boolean }
+  | { id: string; type: 'user_text'; content: string; modelContent?: string; timestamp: number; attachments?: UIAttachment[]; pending?: boolean }
   | { id: string; type: 'assistant_text'; content: string; timestamp: number; model?: string }
   | { id: string; type: 'thinking'; content: string; timestamp: number }
   | { id: string; type: 'tool_use'; toolName: string; toolUseId: string; input: unknown; timestamp: number; parentToolUseId?: string }

src/server/__tests__/sessions.test.ts

@@ -4,6 +4,7 @@
 
 import { describe, it, expect, beforeEach, afterEach } from 'bun:test'
 import * as fs from 'node:fs/promises'
+import { execFileSync } from 'node:child_process'
 import * as path from 'node:path'
 import * as os from 'node:os'
 import { SessionService } from '../services/sessionService.js'
@@ -75,6 +76,34 @@ async function writeSkill(
   )
 }
 
+function git(cwd: string, ...args: string[]): string {
+  return execFileSync('git', args, {
+    cwd,
+    encoding: 'utf8',
+  })
+}
+
+async function createWorkspaceApiGitRepo(baseDir: string): Promise<string> {
+  const workDir = path.join(
+    baseDir,
+    `workspace-api-${Date.now()}-${Math.random().toString(36).slice(2)}`,
+  )
+
+  await fs.mkdir(path.join(workDir, 'src'), { recursive: true })
+  git(workDir, 'init')
+  git(workDir, 'config', 'user.email', 'sessions-api@example.com')
+  git(workDir, 'config', 'user.name', 'Sessions API')
+
+  await fs.writeFile(path.join(workDir, 'tracked.txt'), 'before\n')
+  await fs.writeFile(path.join(workDir, 'src', 'app.ts'), 'export const answer = 42\n')
+  git(workDir, 'add', 'tracked.txt', 'src/app.ts')
+  git(workDir, 'commit', '-m', 'initial')
+
+  await fs.writeFile(path.join(workDir, 'tracked.txt'), 'before\nafter\n')
+
+  return workDir
+}
+
 // Sample entries matching real CLI format
 function makeSnapshotEntry(): Record<string, unknown> {
   return {
@@ -136,6 +165,31 @@ function makeAssistantEntry(content: string, parentUuid?: string): Record<string
   }
 }
 
+function makeAssistantToolUseEntry(
+  toolUses: Array<{ id: string; name: string; input: Record<string, unknown> }>,
+  parentUuid?: string,
+): Record<string, unknown> {
+  return {
+    parentUuid: parentUuid || null,
+    isSidechain: false,
+    type: 'assistant',
+    message: {
+      model: 'claude-opus-4-7',
+      id: `msg_${crypto.randomUUID().slice(0, 20)}`,
+      type: 'message',
+      role: 'assistant',
+      content: toolUses.map((toolUse) => ({
+        type: 'tool_use',
+        id: toolUse.id,
+        name: toolUse.name,
+        input: toolUse.input,
+      })),
+    },
+    uuid: crypto.randomUUID(),
+    timestamp: '2026-01-01T00:02:00.000Z',
+  }
+}
+
 function makeMetaUserEntry(): Record<string, unknown> {
   return {
     parentUuid: null,
@@ -930,6 +984,301 @@ describe('Sessions API', () => {
     )
   })
 
+  it('GET /api/sessions/:id/workspace/status|tree|file|diff should return workspace data', async () => {
+    const workDir = await createWorkspaceApiGitRepo(tmpDir)
+    const { sessionId } = await service.createSession(workDir)
+
+    const statusRes = await fetch(`${baseUrl}/api/sessions/${sessionId}/workspace/status`)
+    expect(statusRes.status).toBe(200)
+    const statusBody = await statusRes.json() as {
+      state: string
+      workDir: string
+      changedFiles: Array<{ path: string; status: string }>
+      isGitRepo: boolean
+    }
+    expect(statusBody.state).toBe('ok')
+    expect(statusBody.workDir).toBe(workDir)
+    expect(statusBody.isGitRepo).toBe(true)
+    expect(statusBody.changedFiles).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({ path: 'tracked.txt', status: 'modified' }),
+      ]),
+    )
+
+    const treeRes = await fetch(`${baseUrl}/api/sessions/${sessionId}/workspace/tree`)
+    expect(treeRes.status).toBe(200)
+    const treeBody = await treeRes.json() as {
+      state: string
+      path: string
+      entries: Array<{ name: string; path: string; isDirectory: boolean }>
+    }
+    expect(treeBody).toMatchObject({
+      state: 'ok',
+      path: '',
+    })
+    expect(treeBody.entries).toEqual([
+      { name: 'src', path: 'src', isDirectory: true },
+      { name: 'tracked.txt', path: 'tracked.txt', isDirectory: false },
+    ])
+
+    const fileRes = await fetch(
+      `${baseUrl}/api/sessions/${sessionId}/workspace/file?path=${encodeURIComponent('src/app.ts')}`,
+    )
+    expect(fileRes.status).toBe(200)
+    const fileBody = await fileRes.json() as {
+      state: string
+      path: string
+      content?: string
+      language: string
+      size: number
+    }
+    expect(fileBody).toMatchObject({
+      state: 'ok',
+      path: 'src/app.ts',
+      language: 'typescript',
+      size: 25,
+      content: 'export const answer = 42\n',
+    })
+
+    const diffRes = await fetch(
+      `${baseUrl}/api/sessions/${sessionId}/workspace/diff?path=${encodeURIComponent('tracked.txt')}`,
+    )
+    expect(diffRes.status).toBe(200)
+    const diffBody = await diffRes.json() as {
+      state: string
+      path: string
+      diff?: string
+    }
+    expect(diffBody.state).toBe('ok')
+    expect(diffBody.path).toBe('tracked.txt')
+    expect(diffBody.diff).toContain('tracked.txt')
+  })
+
+  it('GET /api/sessions/:id/workspace/* should surface transcript changes for a non-git tmp session', async () => {
+    const sessionId = 'bbbbbbbb-cccc-dddd-eeee-ffffffffffff'
+    const workDir = await fs.mkdtemp(path.join(tmpDir, 'workspace-api-non-git-'))
+    const srcDir = path.join(workDir, 'src')
+    const notesDir = path.join(workDir, 'notes')
+    const assetsDir = path.join(workDir, 'assets')
+
+    await fs.mkdir(srcDir, { recursive: true })
+    await fs.mkdir(notesDir, { recursive: true })
+    await fs.mkdir(assetsDir, { recursive: true })
+    await fs.writeFile(path.join(workDir, 'README.md'), '# Temporary project\n')
+    await fs.writeFile(path.join(srcDir, 'app.ts'), 'export const answer = 2\n')
+    await fs.writeFile(path.join(notesDir, 'todo.md'), '- ship workspace panel\n')
+    await fs.writeFile(
+      path.join(assetsDir, 'pixel.png'),
+      Buffer.from(
+        'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/x8AAwMCAO+/p9sAAAAASUVORK5CYII=',
+        'base64',
+      ),
+    )
+
+    await writeSessionFile(sanitizePath(workDir), sessionId, [
+      makeSnapshotEntry(),
+      makeSessionMetaEntry(workDir),
+      makeUserEntry('Update this temporary project'),
+      makeAssistantToolUseEntry([
+        {
+          id: 'toolu-edit-app',
+          name: 'Edit',
+          input: {
+            file_path: path.join(workDir, 'src', 'app.ts'),
+            old_string: 'export const answer = 1\n',
+            new_string: 'export const answer = 2\n',
+          },
+        },
+        {
+          id: 'toolu-write-todo',
+          name: 'Write',
+          input: {
+            file_path: path.join(workDir, 'notes', 'todo.md'),
+            content: '- ship workspace panel\n',
+          },
+        },
+      ]),
+    ])
+
+    const statusRes = await fetch(`${baseUrl}/api/sessions/${sessionId}/workspace/status`)
+    expect(statusRes.status).toBe(200)
+    const statusBody = await statusRes.json() as {
+      state: string
+      workDir: string
+      repoName: string | null
+      branch: string | null
+      isGitRepo: boolean
+      changedFiles: Array<{
+        path: string
+        status: string
+        additions: number
+        deletions: number
+      }>
+    }
+    expect(statusBody).toMatchObject({
+      state: 'ok',
+      workDir,
+      repoName: path.basename(workDir),
+      branch: null,
+      isGitRepo: false,
+    })
+    expect(statusBody.changedFiles).toEqual([
+      expect.objectContaining({
+        path: 'notes/todo.md',
+        status: 'added',
+        additions: 1,
+        deletions: 0,
+      }),
+      expect.objectContaining({
+        path: 'src/app.ts',
+        status: 'modified',
+        additions: 1,
+        deletions: 1,
+      }),
+    ])
+
+    const treeRes = await fetch(`${baseUrl}/api/sessions/${sessionId}/workspace/tree`)
+    expect(treeRes.status).toBe(200)
+    const treeBody = await treeRes.json() as {
+      state: string
+      path: string
+      entries: Array<{ name: string; path: string; isDirectory: boolean }>
+    }
+    expect(treeBody).toMatchObject({ state: 'ok', path: '' })
+    expect(treeBody.entries).toEqual([
+      { name: 'assets', path: 'assets', isDirectory: true },
+      { name: 'notes', path: 'notes', isDirectory: true },
+      { name: 'src', path: 'src', isDirectory: true },
+      { name: 'README.md', path: 'README.md', isDirectory: false },
+    ])
+
+    const srcTreeRes = await fetch(
+      `${baseUrl}/api/sessions/${sessionId}/workspace/tree?path=${encodeURIComponent('src')}`,
+    )
+    expect(srcTreeRes.status).toBe(200)
+    expect(await srcTreeRes.json()).toMatchObject({
+      state: 'ok',
+      path: 'src',
+      entries: [{ name: 'app.ts', path: 'src/app.ts', isDirectory: false }],
+    })
+
+    const fileRes = await fetch(
+      `${baseUrl}/api/sessions/${sessionId}/workspace/file?path=${encodeURIComponent('src/app.ts')}`,
+    )
+    expect(fileRes.status).toBe(200)
+    expect(await fileRes.json()).toMatchObject({
+      state: 'ok',
+      path: 'src/app.ts',
+      previewType: 'text',
+      language: 'typescript',
+      content: 'export const answer = 2\n',
+    })
+
+    const imageRes = await fetch(
+      `${baseUrl}/api/sessions/${sessionId}/workspace/file?path=${encodeURIComponent('assets/pixel.png')}`,
+    )
+    expect(imageRes.status).toBe(200)
+    const imageBody = await imageRes.json() as {
+      state: string
+      path: string
+      previewType: string
+      mimeType: string
+      dataUrl: string
+    }
+    expect(imageBody).toMatchObject({
+      state: 'ok',
+      path: 'assets/pixel.png',
+      previewType: 'image',
+      mimeType: 'image/png',
+    })
+    expect(imageBody.dataUrl).toStartWith('data:image/png;base64,')
+
+    const appDiffRes = await fetch(
+      `${baseUrl}/api/sessions/${sessionId}/workspace/diff?path=${encodeURIComponent('src/app.ts')}`,
+    )
+    expect(appDiffRes.status).toBe(200)
+    const appDiffBody = await appDiffRes.json() as { state: string; path: string; diff?: string }
+    expect(appDiffBody).toMatchObject({ state: 'ok', path: 'src/app.ts' })
+    expect(appDiffBody.diff).toContain('diff --session a/src/app.ts b/src/app.ts')
+    expect(appDiffBody.diff).toContain('-export const answer = 1')
+    expect(appDiffBody.diff).toContain('+export const answer = 2')
+
+    const todoDiffRes = await fetch(
+      `${baseUrl}/api/sessions/${sessionId}/workspace/diff?path=${encodeURIComponent('notes/todo.md')}`,
+    )
+    expect(todoDiffRes.status).toBe(200)
+    const todoDiffBody = await todoDiffRes.json() as { state: string; path: string; diff?: string }
+    expect(todoDiffBody).toMatchObject({ state: 'ok', path: 'notes/todo.md' })
+    expect(todoDiffBody.diff).toContain('--- /dev/null')
+    expect(todoDiffBody.diff).toContain('+++ b/notes/todo.md')
+    expect(todoDiffBody.diff).toContain('+- ship workspace panel')
+  })
+
+  it('GET /api/sessions/:id/workspace/file and diff should require a path query', async () => {
+    const workDir = await createWorkspaceApiGitRepo(tmpDir)
+    const { sessionId } = await service.createSession(workDir)
+
+    for (const route of ['file', 'diff']) {
+      const res = await fetch(`${baseUrl}/api/sessions/${sessionId}/workspace/${route}`)
+      expect(res.status).toBe(400)
+      expect(await res.json()).toMatchObject({
+        error: 'BAD_REQUEST',
+      })
+    }
+  })
+
+  it('GET /api/sessions/:id/workspace/file and tree should reject traversal with 403', async () => {
+    const workDir = await createWorkspaceApiGitRepo(tmpDir)
+    const { sessionId } = await service.createSession(workDir)
+
+    for (const route of ['file', 'tree']) {
+      const res = await fetch(
+        `${baseUrl}/api/sessions/${sessionId}/workspace/${route}?path=${encodeURIComponent('../outside.txt')}`,
+      )
+      expect(res.status).toBe(403)
+      expect(await res.json()).toMatchObject({
+        error: 'FORBIDDEN',
+      })
+    }
+  })
+
+  it('GET /api/sessions/:id/workspace/diff should reject traversal with 403', async () => {
+    const workDir = await createWorkspaceApiGitRepo(tmpDir)
+    const { sessionId } = await service.createSession(workDir)
+
+    const res = await fetch(
+      `${baseUrl}/api/sessions/${sessionId}/workspace/diff?path=${encodeURIComponent('../outside.txt')}`,
+    )
+    expect(res.status).toBe(403)
+    expect(await res.json()).toMatchObject({
+      error: 'FORBIDDEN',
+    })
+  })
+
+  it('GET /api/sessions/:id/workspace/status should 404 for unknown sessions', async () => {
+    const res = await fetch(
+      `${baseUrl}/api/sessions/00000000-0000-0000-0000-000000000000/workspace/status`,
+    )
+    expect(res.status).toBe(404)
+    expect(await res.json()).toMatchObject({
+      error: 'NOT_FOUND',
+    })
+  })
+
+  it('non-GET workspace routes should return 405', async () => {
+    const workDir = await createWorkspaceApiGitRepo(tmpDir)
+    const { sessionId } = await service.createSession(workDir)
+
+    const res = await fetch(`${baseUrl}/api/sessions/${sessionId}/workspace/status`, {
+      method: 'POST',
+    })
+
+    expect(res.status).toBe(405)
+    expect(await res.json()).toMatchObject({
+      error: 'METHOD_NOT_ALLOWED',
+    })
+  })
+
   it('POST /api/sessions/:id/rewind should preview and trim the active conversation chain', async () => {
     const sessionId = 'aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee'
     const firstUserId = crypto.randomUUID()
@@ -1188,6 +1537,65 @@ describe('Sessions API', () => {
     expect(remainingMessages).toHaveLength(0)
   })
 
+  it('POST /api/sessions/:id/rewind should resolve checkpoint paths from the target prompt cwd', async () => {
+    const sessionId = 'bbbbbbbb-bbbb-cccc-dddd-ffffffffffff'
+    const parentDir = path.join(tmpDir, 'nested-cwd-parent')
+    const workDir = path.join(parentDir, 'testbb')
+    const targetFile = path.join(workDir, 'vite.config.js')
+    const userId = crypto.randomUUID()
+    const assistantId = crypto.randomUUID()
+    const laterUserId = crypto.randomUUID()
+    const backupName = 'nested-cwd@v1'
+
+    await fs.mkdir(workDir, { recursive: true })
+    await fs.writeFile(targetFile, "export default 'after'\n", 'utf-8')
+    await writeFileHistoryBackup(sessionId, backupName, "export default 'before'\n")
+
+    await writeSessionFile(sanitizePath(parentDir), sessionId, [
+      makeFileHistorySnapshotEntry(userId, {
+        'testbb/vite.config.js': {
+          backupFileName: backupName,
+          version: 1,
+          backupTime: '2026-01-01T00:00:00.000Z',
+        },
+      }),
+      {
+        ...makeUserEntry('create a nested project', userId),
+        cwd: parentDir,
+        sessionId,
+      },
+      {
+        ...makeAssistantEntry('DONE', userId),
+        uuid: assistantId,
+      },
+      {
+        ...makeUserEntry('latest tool result after cd', laterUserId),
+        cwd: workDir,
+        sessionId,
+      },
+    ])
+
+    const previewRes = await fetch(`${baseUrl}/api/sessions/${sessionId}/rewind`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ userMessageIndex: 0, dryRun: true }),
+    })
+    expect(previewRes.status).toBe(200)
+    const preview = await previewRes.json() as {
+      code: { available: boolean; filesChanged: string[] }
+    }
+    expect(preview.code.available).toBe(true)
+    expect(preview.code.filesChanged).toEqual([targetFile])
+
+    const executeRes = await fetch(`${baseUrl}/api/sessions/${sessionId}/rewind`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ userMessageIndex: 0 }),
+    })
+    expect(executeRes.status).toBe(200)
+    expect(await fs.readFile(targetFile, 'utf-8')).toBe("export default 'before'\n")
+  })
+
   it('POST /api/sessions/:id/rewind should restore multiple files and remove created files', async () => {
     const sessionId = 'cccccccc-bbbb-cccc-dddd-eeeeeeeeeeee'
     const workDir = path.join(tmpDir, 'multi-file-fixture')
@@ -1318,6 +1726,163 @@ describe('Sessions API', () => {
     expect(remainingMessages[0]?.id).toBe(firstUserId)
   })
 
+  it('POST /api/sessions/:id/rewind should keep first-turn file state when undoing only the latest turn', async () => {
+    const sessionId = 'dddddddd-bbbb-cccc-dddd-ffffffffffff'
+    const workDir = path.join(tmpDir, 'two-turns-separate-files')
+    const firstTurnFile = path.join(workDir, 'src', 'first.js')
+    const secondTurnFile = path.join(workDir, 'src', 'second.js')
+    const firstUserId = crypto.randomUUID()
+    const secondUserId = crypto.randomUUID()
+    const firstBaseBackup = 'separate-first@v1'
+    const firstAfterTurnBackup = 'separate-first@v2'
+    const secondBaseBackup = 'separate-second@v1'
+
+    await fs.mkdir(path.dirname(firstTurnFile), { recursive: true })
+    await fs.writeFile(firstTurnFile, "export const FIRST = 'v1'\n", 'utf-8')
+    await fs.writeFile(secondTurnFile, "export const SECOND = 'v2'\n", 'utf-8')
+    await writeFileHistoryBackup(sessionId, firstBaseBackup, "export const FIRST = 'base'\n")
+    await writeFileHistoryBackup(sessionId, firstAfterTurnBackup, "export const FIRST = 'v1'\n")
+    await writeFileHistoryBackup(sessionId, secondBaseBackup, "export const SECOND = 'base'\n")
+
+    await writeSessionFile('-tmp-api-two-turns-separate-files', sessionId, [
+      makeSessionMetaEntry(workDir),
+      makeFileHistorySnapshotEntry(firstUserId, {
+        'src/first.js': {
+          backupFileName: firstBaseBackup,
+          version: 1,
+          backupTime: '2026-01-01T00:00:00.000Z',
+        },
+      }),
+      {
+        ...makeUserEntry('make first file v1', firstUserId),
+        cwd: workDir,
+        sessionId,
+      },
+      makeAssistantEntry('DONE first', firstUserId),
+      makeFileHistorySnapshotEntry(secondUserId, {
+        'src/first.js': {
+          backupFileName: firstAfterTurnBackup,
+          version: 2,
+          backupTime: '2026-01-01T00:00:00.000Z',
+        },
+        'src/second.js': {
+          backupFileName: secondBaseBackup,
+          version: 1,
+          backupTime: '2026-01-01T00:00:00.000Z',
+        },
+      }),
+      {
+        ...makeUserEntry('make second file v2', secondUserId),
+        cwd: workDir,
+        sessionId,
+      },
+      makeAssistantEntry('DONE second', secondUserId),
+    ])
+
+    const previewRes = await fetch(`${baseUrl}/api/sessions/${sessionId}/rewind`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ userMessageIndex: 1, dryRun: true }),
+    })
+    expect(previewRes.status).toBe(200)
+    const preview = await previewRes.json() as {
+      code: { available: boolean; filesChanged: string[] }
+    }
+    expect(preview.code.available).toBe(true)
+    expect(preview.code.filesChanged).toEqual([secondTurnFile])
+
+    const executeRes = await fetch(`${baseUrl}/api/sessions/${sessionId}/rewind`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ userMessageIndex: 1 }),
+    })
+    expect(executeRes.status).toBe(200)
+
+    expect(await fs.readFile(firstTurnFile, 'utf-8')).toBe("export const FIRST = 'v1'\n")
+    expect(await fs.readFile(secondTurnFile, 'utf-8')).toBe("export const SECOND = 'base'\n")
+
+    const remainingMessages = await service.getSessionMessages(sessionId)
+    expect(remainingMessages).toHaveLength(2)
+    expect(remainingMessages[0]?.id).toBe(firstUserId)
+  })
+
+  it('POST /api/sessions/:id/rewind should include files created after the first turn', async () => {
+    const sessionId = 'eeeeeeee-bbbb-cccc-dddd-eeeeeeeeeeee'
+    const workDir = path.join(tmpDir, 'created-on-second-turn')
+    const firstFile = path.join(workDir, 'src', 'step.js')
+    const createdFile = path.join(workDir, 'notes', 'generated.txt')
+    const firstUserId = crypto.randomUUID()
+    const secondUserId = crypto.randomUUID()
+    const backupV1 = 'second-created-step@v1'
+    const backupV2 = 'second-created-step@v2'
+
+    await fs.mkdir(path.dirname(firstFile), { recursive: true })
+    await fs.mkdir(path.dirname(createdFile), { recursive: true })
+    await fs.writeFile(firstFile, "export const STEP = 'v2'\n", 'utf-8')
+    await fs.writeFile(createdFile, 'generated\n', 'utf-8')
+    await writeFileHistoryBackup(sessionId, backupV1, "export const STEP = 'base'\n")
+    await writeFileHistoryBackup(sessionId, backupV2, "export const STEP = 'v1'\n")
+
+    await writeSessionFile('-tmp-api-second-turn-created', sessionId, [
+      makeSessionMetaEntry(workDir),
+      makeFileHistorySnapshotEntry(firstUserId, {
+        'src/step.js': {
+          backupFileName: backupV1,
+          version: 1,
+          backupTime: '2026-01-01T00:00:00.000Z',
+        },
+      }),
+      {
+        ...makeUserEntry('make v1', firstUserId),
+        cwd: workDir,
+        sessionId,
+      },
+      makeAssistantEntry('DONE', firstUserId),
+      makeFileHistorySnapshotEntry(secondUserId, {
+        'src/step.js': {
+          backupFileName: backupV2,
+          version: 2,
+          backupTime: '2026-01-01T00:00:00.000Z',
+        },
+        'notes/generated.txt': {
+          backupFileName: null,
+          version: 2,
+          backupTime: '2026-01-01T00:00:00.000Z',
+        },
+      }),
+      {
+        ...makeUserEntry('make v2 and create file', secondUserId),
+        cwd: workDir,
+        sessionId,
+      },
+      makeAssistantEntry('DONE', secondUserId),
+    ])
+
+    const previewRes = await fetch(`${baseUrl}/api/sessions/${sessionId}/rewind`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ userMessageIndex: 1, dryRun: true }),
+    })
+    expect(previewRes.status).toBe(200)
+    const preview = await previewRes.json() as {
+      code: { available: boolean; filesChanged: string[]; insertions: number }
+    }
+    expect(preview.code.filesChanged.sort()).toEqual([
+      createdFile,
+      firstFile,
+    ].sort())
+    expect(preview.code.insertions).toBe(2)
+
+    const executeRes = await fetch(`${baseUrl}/api/sessions/${sessionId}/rewind`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ userMessageIndex: 1 }),
+    })
+    expect(executeRes.status).toBe(200)
+    expect(await fs.readFile(firstFile, 'utf-8')).toBe("export const STEP = 'v1'\n")
+    await expect(fs.stat(createdFile)).rejects.toMatchObject({ code: 'ENOENT' })
+  })
+
   // --------------------------------------------------------------------------
   // Conversations API via /api/sessions/:id/chat
   // --------------------------------------------------------------------------

src/server/__tests__/workspace-service.test.ts

@@ -0,0 +1,461 @@
+import { afterEach, describe, expect, it } from 'bun:test'
+import * as fs from 'node:fs/promises'
+import { execFileSync } from 'node:child_process'
+import * as os from 'node:os'
+import * as path from 'node:path'
+import { WorkspaceService } from '../services/workspaceService.js'
+
+const cleanupDirs = new Set<string>()
+const ONE_MIB = 1024 * 1024
+
+function trackDir(dir: string): string {
+  cleanupDirs.add(dir)
+  return dir
+}
+
+async function makeTempDir(prefix: string): Promise<string> {
+  return trackDir(await fs.mkdtemp(path.join(os.tmpdir(), prefix)))
+}
+
+function git(cwd: string, ...args: string[]): string {
+  return execFileSync('git', args, {
+    cwd,
+    encoding: 'utf8',
+  })
+}
+
+async function createGitWorkspace(): Promise<string> {
+  const repoDir = await makeTempDir('workspace-service-git-')
+
+  git(repoDir, 'init')
+  git(repoDir, 'config', 'user.email', 'workspace-service@example.com')
+  git(repoDir, 'config', 'user.name', 'Workspace Service')
+
+  await fs.writeFile(path.join(repoDir, 'tracked.txt'), 'before\n')
+  await fs.writeFile(path.join(repoDir, 'deleted.txt'), 'delete me\n')
+  await fs.writeFile(path.join(repoDir, 'clean.txt'), 'clean\n')
+  git(repoDir, 'add', 'tracked.txt', 'deleted.txt', 'clean.txt')
+  git(repoDir, 'commit', '-m', 'initial')
+
+  await fs.writeFile(path.join(repoDir, 'tracked.txt'), 'before\nafter\n')
+  await fs.writeFile(path.join(repoDir, 'new.txt'), 'new file\n')
+  git(repoDir, 'add', 'new.txt')
+  await fs.unlink(path.join(repoDir, 'deleted.txt'))
+  await fs.writeFile(path.join(repoDir, 'untracked.txt'), 'still untracked\n')
+
+  return repoDir
+}
+
+async function createNestedGitWorkspace(): Promise<{
+  repoDir: string
+  workDir: string
+}> {
+  const repoDir = await makeTempDir('workspace-service-nested-git-')
+  const workDir = path.join(repoDir, 'subdir')
+
+  git(repoDir, 'init')
+  git(repoDir, 'config', 'user.email', 'workspace-service@example.com')
+  git(repoDir, 'config', 'user.name', 'Workspace Service')
+
+  await fs.mkdir(workDir)
+  await fs.writeFile(path.join(repoDir, 'root.txt'), 'root original\n')
+  await fs.writeFile(path.join(workDir, 'sub.txt'), 'sub original\n')
+  git(repoDir, 'add', 'root.txt', 'subdir/sub.txt')
+  git(repoDir, 'commit', '-m', 'initial')
+
+  await fs.writeFile(path.join(repoDir, 'root.txt'), 'root original\nroot changed\n')
+  await fs.writeFile(path.join(workDir, 'sub.txt'), 'sub original\nsub changed\n')
+
+  return { repoDir, workDir }
+}
+
+afterEach(async () => {
+  for (const dir of cleanupDirs) {
+    await fs.rm(dir, { recursive: true, force: true })
+  }
+  cleanupDirs.clear()
+})
+
+describe('WorkspaceService', () => {
+  it('returns git status for modified, added, deleted, and untracked files', async () => {
+    const repoDir = await createGitWorkspace()
+    const service = new WorkspaceService(async (sessionId) => sessionId === 'session-1' ? repoDir : null)
+
+    const result = await service.getStatus('session-1')
+
+    expect(result.state).toBe('ok')
+    expect(result.workDir).toBe(repoDir)
+    expect(result.isGitRepo).toBe(true)
+    expect(result.repoName).toBe(path.basename(repoDir))
+    expect(result.branch).toBeTruthy()
+
+    const files = new Map(result.changedFiles.map((file) => [file.path, file]))
+    expect(Array.from(files.keys()).sort()).toEqual([
+      'deleted.txt',
+      'new.txt',
+      'tracked.txt',
+      'untracked.txt',
+    ])
+    expect(files.get('tracked.txt')?.status).toBe('modified')
+    expect(files.get('tracked.txt')?.additions).toBeGreaterThan(0)
+    expect(files.get('new.txt')?.status).toBe('added')
+    expect(files.get('new.txt')?.additions).toBeGreaterThan(0)
+    expect(files.get('deleted.txt')?.status).toBe('deleted')
+    expect(files.get('deleted.txt')?.deletions).toBeGreaterThan(0)
+    expect(files.get('untracked.txt')).toMatchObject({
+      status: 'untracked',
+      additions: 1,
+      deletions: 0,
+    })
+  })
+
+  it('scopes git status and diff paths to a nested workDir inside a repo', async () => {
+    const { repoDir, workDir } = await createNestedGitWorkspace()
+    const service = new WorkspaceService(async (sessionId) => sessionId === 'session-1' ? workDir : null)
+
+    const status = await service.getStatus('session-1')
+
+    expect(status.state).toBe('ok')
+    expect(status.workDir).toBe(workDir)
+    expect(status.repoName).toBe(path.basename(repoDir))
+    expect(status.changedFiles).toHaveLength(1)
+    expect(status.changedFiles[0]).toMatchObject({
+      path: 'sub.txt',
+      status: 'modified',
+    })
+    expect(status.changedFiles[0]?.additions).toBeGreaterThan(0)
+    expect(status.changedFiles[0]?.deletions).toBeGreaterThanOrEqual(0)
+    expect(status.changedFiles.some((file) => file.path === 'root.txt')).toBe(false)
+
+    const diff = await service.getDiff('session-1', 'sub.txt')
+    expect(diff.state).toBe('ok')
+    expect(diff.diff).toContain('subdir/sub.txt')
+    expect(diff.diff?.length).toBeGreaterThan(0)
+  })
+
+  it('returns explicit non-git and missing-workdir states', async () => {
+    const nonGitDir = await makeTempDir('workspace-service-non-git-')
+    const missingDir = path.join(await makeTempDir('workspace-service-missing-parent-'), 'missing')
+    const service = new WorkspaceService(async (sessionId) => {
+      if (sessionId === 'non-git') return nonGitDir
+      if (sessionId === 'missing') return missingDir
+      return null
+    })
+
+    await expect(service.getStatus('unknown')).rejects.toThrow('Session not found: unknown')
+
+    await expect(service.getStatus('non-git')).resolves.toMatchObject({
+      state: 'ok',
+      workDir: nonGitDir,
+      repoName: path.basename(nonGitDir),
+      isGitRepo: false,
+      changedFiles: [],
+    })
+
+    await expect(service.getStatus('missing')).resolves.toMatchObject({
+      state: 'missing_workdir',
+      workDir: missingDir,
+      isGitRepo: false,
+      changedFiles: [],
+    })
+  })
+
+  it('reports session tool edits without requiring a git repository', async () => {
+    const nonGitDir = await makeTempDir('workspace-service-session-changes-')
+    await fs.mkdir(path.join(nonGitDir, 'src'))
+    await fs.writeFile(path.join(nonGitDir, 'src/App.jsx'), 'export default function App() { return <main>New</main> }\n')
+
+    const service = new WorkspaceService(
+      async () => nonGitDir,
+      async () => [{
+        id: 'assistant-1',
+        type: 'tool_use',
+        timestamp: new Date().toISOString(),
+        content: [{
+          type: 'tool_use',
+          name: 'Edit',
+          input: {
+            file_path: 'src/App.jsx',
+            old_string: 'export default function App() { return <main>Old</main> }\n',
+            new_string: 'export default function App() { return <main>New</main> }\n',
+          },
+        }],
+      }],
+    )
+
+    const status = await service.getStatus('session-1')
+
+    expect(status).toMatchObject({
+      state: 'ok',
+      workDir: nonGitDir,
+      isGitRepo: false,
+      changedFiles: [{
+        path: 'src/App.jsx',
+        status: 'modified',
+        additions: 1,
+        deletions: 1,
+      }],
+    })
+
+    const diff = await service.getDiff('session-1', 'src/App.jsx')
+    expect(diff.state).toBe('ok')
+    expect(diff.diff).toContain('diff --session a/src/App.jsx b/src/App.jsx')
+    expect(diff.diff).toContain('-export default function App() { return <main>Old</main> }')
+    expect(diff.diff).toContain('+export default function App() { return <main>New</main> }')
+  })
+
+  it('rejects traversal attempts for file, diff, and tree access', async () => {
+    const repoDir = await createGitWorkspace()
+    const service = new WorkspaceService(async () => repoDir)
+
+    await expect(service.readFile('session-1', '../outside.txt')).rejects.toThrow(/outside workspace/)
+    await expect(service.getDiff('session-1', '../outside.txt')).resolves.toMatchObject({
+      state: 'error',
+      path: '../outside.txt',
+    })
+    await expect(service.readTree('session-1', '../outside')).rejects.toThrow(/outside workspace/)
+  })
+
+  it('rejects symlink targets that escape the workspace root', async () => {
+    const workDir = await makeTempDir('workspace-service-symlink-')
+    const outsideDir = await makeTempDir('workspace-service-symlink-outside-')
+    const outsideFile = path.join(outsideDir, 'secret.txt')
+    await fs.writeFile(outsideFile, 'top secret\n')
+    await fs.symlink(outsideFile, path.join(workDir, 'escape.txt'))
+
+    const service = new WorkspaceService(async () => workDir)
+
+    await expect(service.readFile('session-1', 'escape.txt')).rejects.toThrow(/outside workspace/)
+  })
+
+  it('returns error for an untracked symlink that escapes the workspace root', async () => {
+    const repoDir = await makeTempDir('workspace-service-symlink-git-')
+    const outsideDir = await makeTempDir('workspace-service-symlink-git-outside-')
+    const outsideFile = path.join(outsideDir, 'secret.txt')
+
+    git(repoDir, 'init')
+    git(repoDir, 'config', 'user.email', 'workspace-service@example.com')
+    git(repoDir, 'config', 'user.name', 'Workspace Service')
+    await fs.writeFile(path.join(repoDir, 'tracked.txt'), 'tracked\n')
+    git(repoDir, 'add', 'tracked.txt')
+    git(repoDir, 'commit', '-m', 'initial')
+
+    await fs.writeFile(outsideFile, 'top secret\n')
+    await fs.symlink(outsideFile, path.join(repoDir, 'escape.txt'))
+
+    const service = new WorkspaceService(async () => repoDir)
+
+    const status = await service.getStatus('session-1')
+    expect(status.state).toBe('error')
+    expect(status.error).toMatch(/outside workspace/)
+
+    await expect(service.getDiff('session-1', 'escape.txt')).resolves.toMatchObject({
+      state: 'error',
+      path: 'escape.txt',
+    })
+    const diffOutcome = await service.getDiff('session-1', 'escape.txt')
+    expect(diffOutcome.error).toMatch(/outside workspace/)
+  })
+
+  it('returns explicit readFile states for text, binary, large, and missing targets', async () => {
+    const workDir = await makeTempDir('workspace-service-files-')
+    const service = new WorkspaceService(async () => workDir)
+
+    await fs.writeFile(path.join(workDir, 'note.ts'), 'export const answer = 42\n')
+    await fs.writeFile(path.join(workDir, 'binary.bin'), Buffer.from([0, 1, 2, 3]))
+    await fs.writeFile(path.join(workDir, 'image.png'), Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x00]))
+    await fs.writeFile(
+      path.join(workDir, 'large-image.png'),
+      Buffer.concat([Buffer.from([0x89, 0x50, 0x4e, 0x47]), Buffer.alloc(ONE_MIB + 1, 0xff)]),
+    )
+    await fs.writeFile(path.join(workDir, 'large.txt'), Buffer.alloc(ONE_MIB + 1, 'a'))
+    await fs.mkdir(path.join(workDir, 'folder'))
+
+    await expect(service.readFile('session-1', 'note.ts')).resolves.toMatchObject({
+      state: 'ok',
+      language: 'typescript',
+      size: 25,
+      content: 'export const answer = 42\n',
+    })
+    await expect(service.readFile('session-1', 'binary.bin')).resolves.toMatchObject({
+      state: 'binary',
+      language: 'binary',
+      size: 4,
+    })
+    await expect(service.readFile('session-1', 'image.png')).resolves.toMatchObject({
+      state: 'ok',
+      previewType: 'image',
+      language: 'image',
+      mimeType: 'image/png',
+      dataUrl: 'data:image/png;base64,iVBORwA=',
+      size: 5,
+    })
+    const largeImage = await service.readFile('session-1', 'large-image.png')
+    expect(largeImage).toMatchObject({
+      state: 'ok',
+      previewType: 'image',
+      language: 'image',
+      mimeType: 'image/png',
+      size: ONE_MIB + 5,
+    })
+    expect(largeImage.dataUrl).toStartWith('data:image/png;base64,')
+    await expect(service.readFile('session-1', 'large.txt')).resolves.toMatchObject({
+      state: 'ok',
+      previewType: 'text',
+      language: 'text',
+      size: ONE_MIB + 1,
+      readBytes: ONE_MIB,
+      truncated: true,
+      content: 'a'.repeat(ONE_MIB),
+    })
+    await expect(service.readFile('session-1', 'missing.txt')).resolves.toMatchObject({
+      state: 'missing',
+    })
+    await expect(service.readFile('session-1', 'folder')).resolves.toMatchObject({
+      state: 'missing',
+    })
+  })
+
+  it('lists a single directory level with dotfiles excluded and directories first', async () => {
+    const workDir = await makeTempDir('workspace-service-tree-')
+    const service = new WorkspaceService(async () => workDir)
+
+    await fs.mkdir(path.join(workDir, 'b-dir'))
+    await fs.mkdir(path.join(workDir, 'a-dir'))
+    await fs.mkdir(path.join(workDir, 'a-dir', 'inner'))
+    await fs.writeFile(path.join(workDir, 'a-dir', 'note.txt'), 'nested\n')
+    await fs.writeFile(path.join(workDir, 'z-file.txt'), 'root file\n')
+    await fs.writeFile(path.join(workDir, '.hidden.txt'), 'ignore\n')
+
+    await expect(service.readTree('session-1')).resolves.toMatchObject({
+      state: 'ok',
+      path: '',
+      entries: [
+        { name: 'a-dir', path: 'a-dir', isDirectory: true },
+        { name: 'b-dir', path: 'b-dir', isDirectory: true },
+        { name: 'z-file.txt', path: 'z-file.txt', isDirectory: false },
+      ],
+    })
+
+    await expect(service.readTree('session-1', 'a-dir')).resolves.toMatchObject({
+      state: 'ok',
+      path: 'a-dir',
+      entries: [
+        { name: 'inner', path: 'a-dir/inner', isDirectory: true },
+        { name: 'note.txt', path: 'a-dir/note.txt', isDirectory: false },
+      ],
+    })
+  })
+
+  it('returns diffs for modified, added, deleted, and untracked files', async () => {
+    const repoDir = await createGitWorkspace()
+    const service = new WorkspaceService(async (sessionId) => sessionId === 'session-1' ? repoDir : null)
+
+    const modified = await service.getDiff('session-1', 'tracked.txt')
+    expect(modified.state).toBe('ok')
+    expect(modified.diff).toContain('tracked.txt')
+    expect(modified.diff.length).toBeGreaterThan(0)
+
+    const added = await service.getDiff('session-1', 'new.txt')
+    expect(added.state).toBe('ok')
+    expect(added.diff).toContain('new.txt')
+    expect(added.diff.length).toBeGreaterThan(0)
+
+    const deleted = await service.getDiff('session-1', 'deleted.txt')
+    expect(deleted.state).toBe('ok')
+    expect(deleted.diff).toContain('deleted.txt')
+    expect(deleted.diff.length).toBeGreaterThan(0)
+
+    const untracked = await service.getDiff('session-1', 'untracked.txt')
+    expect(untracked.state).toBe('ok')
+    expect(untracked.diff).toContain('untracked.txt')
+    expect(untracked.diff.length).toBeGreaterThan(0)
+
+    await expect(service.getDiff('session-1', 'clean.txt')).resolves.toMatchObject({
+      state: 'missing',
+      path: 'clean.txt',
+    })
+
+    const nonGitDir = await makeTempDir('workspace-service-diff-non-git-')
+    const nonGitService = new WorkspaceService(async () => nonGitDir)
+    await expect(nonGitService.getDiff('session-1', 'whatever.txt')).resolves.toMatchObject({
+      state: 'not_git_repo',
+      path: 'whatever.txt',
+    })
+  })
+
+  it('returns explicit error state when git status fails instead of ok-empty', async () => {
+    const repoDir = await createGitWorkspace()
+    const service = new WorkspaceService(async () => repoDir) as WorkspaceService & {
+      runGit: (workDir: string, args: string[]) => Promise<{
+        stdout: string
+        stderr: string
+        code: number
+      }>
+    }
+
+    service.runGit = async (workDir, args) => {
+      if (args[0] === 'rev-parse' && args[1] === '--show-toplevel') {
+        return { stdout: `${workDir}\n`, stderr: '', code: 0 }
+      }
+      if (args[0] === 'rev-parse' && args[1] === '--abbrev-ref') {
+        return { stdout: 'main\n', stderr: '', code: 0 }
+      }
+      if (args[0] === 'status') {
+        return { stdout: '', stderr: 'fatal: synthetic git failure', code: 1 }
+      }
+      return { stdout: '', stderr: 'unexpected call', code: 1 }
+    }
+
+    await expect(service.getStatus('session-1')).resolves.toMatchObject({
+      state: 'error',
+      isGitRepo: true,
+    })
+
+    const result = await service.getStatus('session-1')
+    expect(result.state).toBe('error')
+    expect(result.changedFiles).toEqual([])
+    expect(result.error).toContain('Failed to read git status')
+    expect(result.error).toContain('synthetic git failure')
+  })
+
+  it('reads tracked diff stats in one bulk git call', async () => {
+    const repoDir = await makeTempDir('workspace-service-bulk-stats-')
+    await fs.writeFile(path.join(repoDir, 'a.txt'), 'a\n')
+    await fs.writeFile(path.join(repoDir, 'b.txt'), 'b\n')
+    const diffStatCalls: string[][] = []
+    const service = new WorkspaceService(async () => repoDir) as WorkspaceService & {
+      runGit: (workDir: string, args: string[]) => Promise<{
+        stdout: string
+        stderr: string
+        code: number
+      }>
+    }
+
+    service.runGit = async (_workDir, args) => {
+      if (args[0] === 'rev-parse' && args[1] === '--show-toplevel') {
+        return { stdout: `${repoDir}\n`, stderr: '', code: 0 }
+      }
+      if (args[0] === 'rev-parse' && args[1] === '--abbrev-ref') {
+        return { stdout: 'main\n', stderr: '', code: 0 }
+      }
+      if (args[0] === 'status') {
+        return { stdout: ' M a.txt\0 M b.txt\0', stderr: '', code: 0 }
+      }
+      if (args[0] === 'diff' && args.includes('--numstat')) {
+        diffStatCalls.push(args)
+        return { stdout: '1\t0\ta.txt\n2\t3\tb.txt\n', stderr: '', code: 0 }
+      }
+      return { stdout: '', stderr: `unexpected git call: ${args.join(' ')}`, code: 1 }
+    }
+
+    const result = await service.getStatus('session-1')
+
+    expect(result.state).toBe('ok')
+    expect(diffStatCalls).toHaveLength(1)
+    expect(result.changedFiles).toEqual([
+      { path: 'a.txt', oldPath: undefined, status: 'modified', additions: 1, deletions: 0 },
+      { path: 'b.txt', oldPath: undefined, status: 'modified', additions: 2, deletions: 3 },
+    ])
+  })
+})

src/server/api/sessions.ts

@@ -18,12 +18,18 @@ import { ApiError, errorResponse } from '../middleware/errorHandler.js'
 import { getSlashCommands } from '../ws/handler.js'
 import { getCommandName } from '../../commands.js'
 import { getSkillDirCommands } from '../../skills/loadSkillsDir.js'
+import { WorkspaceService } from '../services/workspaceService.js'
 import {
   executeSessionRewind,
   previewSessionRewind,
   type RewindTargetSelector,
 } from '../services/sessionRewindService.js'
 
+const workspaceService = new WorkspaceService(async (sessionId) => (
+  conversationService.getSessionWorkDir(sessionId) ||
+  await sessionService.getSessionWorkDir(sessionId)
+), async (sessionId) => sessionService.getSessionMessages(sessionId))
+
 export async function handleSessionsApi(
   req: Request,
   url: URL,
@@ -109,6 +115,16 @@ export async function handleSessionsApi(
       return await getSessionInspection(sessionId, url)
     }
 
+    if (subResource === 'workspace') {
+      if (req.method !== 'GET') {
+        return Response.json(
+          { error: 'METHOD_NOT_ALLOWED', message: `Method ${req.method} not allowed` },
+          { status: 405 }
+        )
+      }
+      return await handleSessionWorkspaceRoute(sessionId, url, segments[4])
+    }
+
     // Route to conversations handler if sub-resource is 'chat'
     if (subResource === 'chat') {
       // This is handled by the conversations API, but in case the router
@@ -174,6 +190,36 @@ async function getSessionMessages(sessionId: string): Promise<Response> {
   return Response.json({ messages })
 }
 
+async function handleSessionWorkspaceRoute(
+  sessionId: string,
+  url: URL,
+  workspaceResource?: string,
+): Promise<Response> {
+  await requireSessionWorkspace(sessionId)
+
+  switch (workspaceResource) {
+    case 'status':
+      return Response.json(await workspaceService.getStatus(sessionId))
+    case 'tree':
+      return await runWorkspaceRequest(() => workspaceService.readTree(
+        sessionId,
+        url.searchParams.get('path') || '',
+      ))
+    case 'file':
+      return await runWorkspaceRequest(() => workspaceService.readFile(
+        sessionId,
+        requireWorkspacePath(url, 'file'),
+      ))
+    case 'diff':
+      return await runWorkspaceDiffRequest(() => workspaceService.getDiff(
+        sessionId,
+        requireWorkspacePath(url, 'diff'),
+      ))
+    default:
+      throw ApiError.notFound(`Unknown workspace resource: ${workspaceResource || 'workspace'}`)
+  }
+}
+
 async function createSession(req: Request): Promise<Response> {
   let body: { workDir?: string }
   try {
@@ -190,6 +236,61 @@ async function createSession(req: Request): Promise<Response> {
   return Response.json(result, { status: 201 })
 }
 
+async function requireSessionWorkspace(sessionId: string): Promise<string> {
+  const workDir =
+    conversationService.getSessionWorkDir(sessionId) ||
+    await sessionService.getSessionWorkDir(sessionId)
+
+  if (!workDir) {
+    throw ApiError.notFound(`Session not found: ${sessionId}`)
+  }
+
+  return workDir
+}
+
+function requireWorkspacePath(url: URL, route: 'file' | 'diff'): string {
+  const filePath = url.searchParams.get('path')
+  if (!filePath) {
+    throw ApiError.badRequest(`path query parameter is required for workspace ${route}`)
+  }
+  return filePath
+}
+
+async function runWorkspaceRequest<T>(operation: () => Promise<T>): Promise<Response> {
+  try {
+    return Response.json(await operation())
+  } catch (error) {
+    if (isOutsideWorkspaceError(error)) {
+      throw new ApiError(403, error.message, 'FORBIDDEN')
+    }
+    if (isSessionNotFoundError(error)) {
+      throw ApiError.notFound(error.message)
+    }
+    throw error
+  }
+}
+
+async function runWorkspaceDiffRequest<T extends { state?: string; error?: string }>(
+  operation: () => Promise<T>,
+): Promise<Response> {
+  const result = await runWorkspaceRequest(operation)
+  const body = await result.clone().json() as T
+
+  if (body.state === 'error' && typeof body.error === 'string' && body.error.includes('outside workspace')) {
+    throw new ApiError(403, body.error, 'FORBIDDEN')
+  }
+
+  return result
+}
+
+function isOutsideWorkspaceError(error: unknown): error is Error {
+  return error instanceof Error && error.message.includes('outside workspace')
+}
+
+function isSessionNotFoundError(error: unknown): error is Error {
+  return error instanceof Error && error.message.startsWith('Session not found:')
+}
+
 async function deleteSession(sessionId: string): Promise<Response> {
   await sessionService.deleteSession(sessionId)
   return Response.json({ ok: true })

src/server/index.ts

@@ -15,6 +15,7 @@ import { handleProxyRequest } from './proxy/handler.js'
 import { ProviderService } from './services/providerService.js'
 import { handleHahaOAuthCallback } from './api/haha-oauth.js'
 import { ensureDesktopCliLauncherInstalled } from './services/desktopCliLauncherService.js'
+import { enableConfigs } from '../utils/config.js'
 
 function readArgValue(flag: string): string | undefined {
   const args = process.argv.slice(2)
@@ -46,6 +47,7 @@ const PORT = SERVER_OPTIONS.port
 const HOST = SERVER_OPTIONS.host
 
 export function startServer(port = PORT, host = HOST) {
+  enableConfigs()
   ProviderService.setServerPort(port)
   const localConnectHost =
     host === '0.0.0.0' || host === '127.0.0.1' || host === 'localhost'

src/server/services/sessionRewindService.ts

@@ -215,6 +215,19 @@ function getBackupFileNameFirstVersion(
   return undefined
 }
 
+function getBackupFileNameForTarget(
+  trackingPath: string,
+  snapshots: FileHistorySnapshot[],
+  targetSnapshot: FileHistorySnapshot,
+): string | null | undefined {
+  const targetBackup = targetSnapshot.trackedFileBackups[trackingPath]
+  if (targetBackup && 'backupFileName' in targetBackup) {
+    return targetBackup.backupFileName
+  }
+
+  return getBackupFileNameFirstVersion(trackingPath, snapshots)
+}
+
 async function readFileOrNull(filePath: string): Promise<string | null> {
   try {
     return await readFile(filePath, 'utf-8')
@@ -223,6 +236,12 @@ async function readFileOrNull(filePath: string): Promise<string | null> {
   }
 }
 
+function countInsertedLines(content: string): number {
+  return diffLines('', content).reduce((total, change) => (
+    change.added ? total + (change.count || 0) : total
+  ), 0)
+}
+
 async function hasFileChanged(
   filePath: string,
   backupFilePath: string,
@@ -265,7 +284,7 @@ async function restoreBackupFile(
 
 async function buildCodePreview(
   sessionId: string,
-  workDir: string,
+  checkpointBaseDir: string,
   targetUserMessageId: string,
 ): Promise<{
   snapshots: FileHistorySnapshot[] | null
@@ -305,21 +324,21 @@ async function buildCodePreview(
   let deletions = 0
 
   for (const trackingPath of trackedPaths) {
-    const targetBackup = targetSnapshot.trackedFileBackups[trackingPath]
-    const backupFileName =
-      targetBackup?.backupFileName ??
-      getBackupFileNameFirstVersion(trackingPath, snapshots)
+    const backupFileName = getBackupFileNameForTarget(
+      trackingPath,
+      snapshots,
+      targetSnapshot,
+    )
 
     if (backupFileName === undefined) continue
 
-    const absolutePath = expandTrackingPath(workDir, trackingPath)
+    const absolutePath = expandTrackingPath(checkpointBaseDir, trackingPath)
 
     if (backupFileName === null) {
-      try {
-        await stat(absolutePath)
+      const currentContent = await readFileOrNull(absolutePath)
+      if (currentContent !== null) {
         filesChanged.push(absolutePath)
-      } catch {
-        // File is already absent.
+        insertions += countInsertedLines(currentContent)
       }
       continue
     }
@@ -365,9 +384,12 @@ export async function previewSessionRewind(
       : null) ||
     (await sessionService.getSessionWorkDir(sessionId)) ||
     process.cwd()
+  const checkpointBaseDir =
+    (await sessionService.getSessionMessageCwd(sessionId, target.targetUserMessageId)) ||
+    workDir
   const { preview } = await buildCodePreview(
     sessionId,
-    workDir,
+    checkpointBaseDir,
     target.targetUserMessageId,
   )
 
@@ -395,9 +417,12 @@ export async function executeSessionRewind(
       : null) ||
     (await sessionService.getSessionWorkDir(sessionId)) ||
     process.cwd()
+  const checkpointBaseDir =
+    (await sessionService.getSessionMessageCwd(sessionId, target.targetUserMessageId)) ||
+    workDir
   const { snapshots, preview } = await buildCodePreview(
     sessionId,
-    workDir,
+    checkpointBaseDir,
     target.targetUserMessageId,
   )
 
@@ -412,14 +437,15 @@ export async function executeSessionRewind(
     }
 
     for (const trackingPath of collectTrackedPaths(snapshots)) {
-      const targetBackup = targetSnapshot.trackedFileBackups[trackingPath]
-      const backupFileName =
-        targetBackup?.backupFileName ??
-        getBackupFileNameFirstVersion(trackingPath, snapshots)
+      const backupFileName = getBackupFileNameForTarget(
+        trackingPath,
+        snapshots,
+        targetSnapshot,
+      )
 
       if (backupFileName === undefined) continue
 
-      const absolutePath = expandTrackingPath(workDir, trackingPath)
+      const absolutePath = expandTrackingPath(checkpointBaseDir, trackingPath)
 
       if (backupFileName === null) {
         try {

src/server/services/sessionService.ts

@@ -1224,6 +1224,18 @@ export class SessionService {
     return this.resolveWorkDirFromEntries(entries, found.projectDir)
   }
 
+  async getSessionMessageCwd(
+    sessionId: string,
+    messageId: string,
+  ): Promise<string | null> {
+    const found = await this.findSessionFile(sessionId)
+    if (!found) return null
+
+    const entries = await this.readJsonlFile(found.filePath)
+    const entry = entries.find((candidate) => candidate.uuid === messageId)
+    return typeof entry?.cwd === 'string' && entry.cwd.trim() ? entry.cwd : null
+  }
+
   /**
    * Inspect how a session should be launched.
    * Placeholder desktop-created sessions have zero transcript messages.