feat: add last-turn diff view

Adds a Last turn scope to DiffView that renders OpenCode snapshot diffs from the latest user message summary without re-fetching git contents. The view hides Review in that mode and carries the selected diff scope through main and context-panel navigation.

Connects latest-turn changed-file chips in chat to the snapshot diff view on desktop and mobile, while keeping older turn chips static/read-only to avoid misleading affordances and extra subscriptions. Updates localized labels and empty states plus changelog.

Validation: bun run type-check (packages/ui); bun run lint (packages/ui).

packages/ui/src/components/chat/MessageList.tsx

@@ -752,6 +752,7 @@ const TurnBlock = React.memo(({
                     activityOwnerMessageId,
                     isFirstAssistantInTurn: isFirstAssistant,
                     isLastAssistantInTurn: isLastAssistant,
+                    isLatestTurn: isLastTurn,
                     isWorking: isLastTurn && sessionIsWorking && (
                         chatRenderMode === 'sorted'
                             ? hasAnchoredActivitySegment

packages/ui/src/components/chat/TurnChangedFilesDropdown.tsx

@@ -4,13 +4,11 @@ import { Popover } from '@base-ui/react/popover';
 import { useDirectoryStore } from '@/stores/useDirectoryStore';
 import { useIsGitRepo } from '@/stores/useGitStore';
 import { useUIStore } from '@/stores/useUIStore';
-import { RuntimeAPIContext } from '@/contexts/runtimeAPIContext';
 import {
     type ChangedFile,
     type ChangedFileEntry,
     FILE_EDIT_TOOLS,
     extractChangedFiles,
-    isGitFile,
     toRelativePath,
 } from './changedFiles';
 import { ChangedFilesList } from './ChangedFilesList';
@@ -18,7 +16,6 @@ import { changedFilesPopoverClassName, changedFilesPopoverStyle } from './change
 import { Tooltip, TooltipContent, TooltipTrigger } from '@/components/ui/tooltip';
 import { Icon } from "@/components/icon/Icon";
 import type { TurnActivityRecord } from './lib/turns/types';
-import { toAbsoluteFilePath } from '@/lib/path-utils';
 
 interface TurnChangedFilesDropdownProps {
     activityParts: TurnActivityRecord[] | undefined;
@@ -29,7 +26,6 @@ export const TurnChangedFilesDropdown: React.FC<TurnChangedFilesDropdownProps> =
     const [portalContainer, setPortalContainer] = React.useState<HTMLElement | null>(null);
     const triggerButtonRef = React.useRef<HTMLButtonElement | null>(null);
     const currentDirectory = useDirectoryStore((s) => s.currentDirectory);
-    const runtime = React.useContext(RuntimeAPIContext);
     const isGitRepo = useIsGitRepo(currentDirectory);
 
     const changedFiles = React.useMemo<ChangedFile[]>(() => {
@@ -56,24 +52,16 @@ export const TurnChangedFilesDropdown: React.FC<TurnChangedFilesDropdownProps> =
 
     const handleOpenFile = (file: ChangedFileEntry) => {
         if (!currentDirectory) return;
-        if (isGitFile(file)) return;
-
-        const absolutePath = toAbsoluteFilePath(currentDirectory, file.path);
-
-        const editor = runtime?.editor;
-        if (editor) {
-            void editor.openFile(absolutePath);
-            setIsExpanded(false);
-            return;
-        }
 
         const store = useUIStore.getState();
+        const relativePath = toRelativePath(file.path, currentDirectory);
         if (!store.isMobile) {
-            store.openContextFile(currentDirectory, absolutePath);
+            store.openContextDiff(currentDirectory, relativePath, false, 'turn');
             setIsExpanded(false);
             return;
         }
-        store.navigateToDiff(toRelativePath(file.path, currentDirectory));
+
+        store.navigateToDiff(relativePath, false, 'turn');
         store.setRightSidebarOpen(false);
         setIsExpanded(false);
     };

packages/ui/src/components/chat/lib/turns/types.ts

@@ -115,6 +115,7 @@ export interface TurnGroupingContext {
     activityOwnerMessageId?: string;
     isFirstAssistantInTurn: boolean;
     isLastAssistantInTurn: boolean;
+    isLatestTurn: boolean;
     summaryBody?: string;
     activityParts?: TurnActivityRecord[];
     activityGroupSegments?: TurnActivityGroup[];

packages/ui/src/components/chat/message/MessageBody.tsx

@@ -65,37 +65,88 @@ const getDisplayFileName = (file: string): string => {
     return segments.at(-1) ?? file;
 };
 
-const TurnChangedFilePills = React.memo(({ files }: { files?: TurnChangedFile[] }) => {
-    if (!files || files.length === 0) {
-        return null;
-    }
+const TurnChangedFileChipContent = React.memo(({ file, interactive = false }: { file: TurnChangedFile; interactive?: boolean }) => (
+    <span
+        className={cn(
+            'inline-flex max-w-full items-center gap-1.5 rounded-lg border border-border/30 bg-muted/30 px-2 py-1 text-xs leading-[1.35] text-muted-foreground',
+            interactive && 'transition-colors hover:border-border/60 hover:bg-interactive-hover'
+        )}
+    >
+        <FileTypeIcon filePath={file.file} className="h-3.5 w-3.5 flex-shrink-0" />
+        <span className="max-w-52 truncate text-foreground/80" title={file.file}>{getDisplayFileName(file.file)}</span>
+        <span className="flex-shrink-0 inline-flex items-center gap-0 typography-meta" style={{ fontSize: '0.8rem', lineHeight: '1' }}>
+            <span style={{ color: 'var(--status-success)' }}>+{file.additions}</span>
+            <span className="text-muted-foreground/70">/</span>
+            <span style={{ color: 'var(--status-error)' }}>-{file.deletions}</span>
+        </span>
+    </span>
+));
+
+const TurnChangedFilePillButton = React.memo(({
+    file,
+    onOpen,
+}: {
+    file: TurnChangedFile;
+    onOpen: (file: string) => void;
+}) => {
+    const { t } = useI18n();
+    return (
+        <button
+            type="button"
+            className="inline-flex h-8 max-w-full cursor-pointer items-center rounded-lg outline-none focus-visible:ring-2 focus-visible:ring-[var(--interactive-focus-ring)]"
+            aria-label={t('chat.changedFiles.actions.openFileTitle', { path: file.file })}
+            title={file.file}
+            onClick={(event) => {
+                event.preventDefault();
+                event.stopPropagation();
+                onOpen(file.file);
+            }}
+        >
+            <TurnChangedFileChipContent file={file} interactive />
+        </button>
+    );
+});
+
+const StaticTurnChangedFilePills = React.memo(({ files }: { files: TurnChangedFile[] }) => (
+    <>
+        {files.map((file) => (
+            <span key={file.file} className="inline-flex h-8 max-w-full items-center" title={file.file}>
+                <TurnChangedFileChipContent file={file} />
+            </span>
+        ))}
+    </>
+));
+
+const InteractiveTurnChangedFilePills = React.memo(({ files }: { files: TurnChangedFile[] }) => {
+    const effectiveDirectory = useEffectiveDirectory();
+    const isMobile = useUIStore((state) => state.isMobile);
+    const navigateToDiff = useUIStore((state) => state.navigateToDiff);
+    const openContextDiff = useUIStore((state) => state.openContextDiff);
+
+    const openLastTurnDiff = React.useCallback((file: string) => {
+        if (!isMobile && effectiveDirectory) {
+            openContextDiff(effectiveDirectory, file, false, 'turn');
+            return;
+        }
+
+        navigateToDiff(file, false, 'turn');
+    }, [effectiveDirectory, isMobile, navigateToDiff, openContextDiff]);
 
     return (
         <>
-            {files.map((file) => {
-                return (
-                    <Tooltip key={file.file}>
-                        <TooltipTrigger asChild>
-                            <span className="inline-flex h-8 max-w-full items-center">
-                                <span className="inline-flex max-w-full items-center gap-1.5 rounded-lg border border-border/30 bg-muted/30 px-2 py-1 text-xs leading-[1.35] text-muted-foreground">
-                                    <FileTypeIcon filePath={file.file} className="h-3.5 w-3.5 flex-shrink-0" />
-                                    <span className="max-w-52 truncate text-foreground/80" title={file.file}>{getDisplayFileName(file.file)}</span>
-                                    <span className="flex-shrink-0 inline-flex items-center gap-0 typography-meta" style={{ fontSize: '0.8rem', lineHeight: '1' }}>
-                                        <span style={{ color: 'var(--status-success)' }}>+{file.additions}</span>
-                                        <span className="text-muted-foreground/70">/</span>
-                                        <span style={{ color: 'var(--status-error)' }}>-{file.deletions}</span>
-                                    </span>
-                                </span>
-                            </span>
-                        </TooltipTrigger>
-                        <TooltipContent>{file.file}</TooltipContent>
-                    </Tooltip>
-                );
-            })}
+            {files.map((file) => (
+                <TurnChangedFilePillButton key={file.file} file={file} onOpen={openLastTurnDiff} />
+            ))}
         </>
     );
 });
 
+const TurnChangedFilePills = React.memo(({ files, isInteractive }: { files?: TurnChangedFile[]; isInteractive: boolean }) => {
+    if (!files || files.length === 0) return null;
+
+    return isInteractive ? <InteractiveTurnChangedFilePills files={files} /> : <StaticTurnChangedFilePills files={files} />;
+});
+
 type SubtaskPartLike = Part & {
     type: 'subtask';
     description?: unknown;
@@ -2079,7 +2130,10 @@ const AssistantMessageBody = React.memo(({
                             <TurnChangedFilesDropdown activityParts={turnGroupingContext?.activityParts} />
                         ) : null}
                         {!isMiniChatSurface && isLastAssistantInTurn && hasStopFinish ? (
-                            <TurnChangedFilePills files={turnGroupingContext?.changedFiles} />
+                            <TurnChangedFilePills
+                                files={turnGroupingContext?.changedFiles}
+                                isInteractive={turnGroupingContext?.isLatestTurn === true}
+                            />
                         ) : null}
                     </div>
                 )}

packages/ui/src/components/chat/message/renderCompare.ts

@@ -280,6 +280,7 @@ export const areRelevantTurnGroupingContextsEqual = (
   if (left.turnId !== right.turnId) return false;
   if (left.isFirstAssistantInTurn !== right.isFirstAssistantInTurn) return false;
   if (left.isLastAssistantInTurn !== right.isLastAssistantInTurn) return false;
+  if (left.isLatestTurn !== right.isLatestTurn) return false;
   if (left.isWorking !== right.isWorking) return false;
   if (left.hasTools !== right.hasTools) return false;
   if (left.hasReasoning !== right.hasReasoning) return false;