fix(desktop): clarify partial transcript ranges

apps/desktop/src/main/__tests__/desktop-transcript-range-store.test.ts

@@ -25,7 +25,10 @@ import {
   encodeDesktopTranscriptChange,
   encodeDesktopTranscriptSnapshot,
 } from '../desktop-transcript-ipc.js';
-import { DESKTOP_TRANSCRIPT_FRAGMENT_MAX_BYTES } from '../../preload/transcript-contract.js';
+import {
+  DESKTOP_TRANSCRIPT_FRAGMENT_MAX_BYTES,
+  DESKTOP_TRANSCRIPT_RANGE_MAX_BYTES,
+} from '../../preload/transcript-contract.js';
 import {
   createDesktopTranscriptRangeController,
   DesktopTranscriptRangeStore,
@@ -297,6 +300,100 @@ test('loads a history target with newer messages available below it', async () =
   assert.equal(replica.snapshot().hasNewer, true);
 });
 
+test('keeps an oversized transcript sparse while moving between indexed prompts', async () => {
+  const messages = syntheticLargeTranscript();
+  const totalBytes = messages.reduce(
+    (total, entry) => total + Buffer.byteLength(JSON.stringify(entry.message), 'utf8'),
+    0,
+  );
+  assert.ok(totalBytes > DESKTOP_TRANSCRIPT_RANGE_MAX_BYTES * 2);
+
+  const bootstrapPage = transcriptPage('older', 'older', 15);
+  const historicalPage = transcriptPage('newer', 'newer', 15);
+  const intermediatePage = transcriptPage('newer', 'newer', 15);
+  const latestPage = transcriptPage('older', 'older', 15);
+  const requests: Array<{
+    direction: 'older' | 'newer';
+    anchorSequence: number | null;
+    maxBytes: number;
+  }> = [];
+  const rendererStore = transcriptStore();
+  const generation = 'oversized-range';
+  const handle = runtimeHostSessionFixture({
+    snapshot: continuitySnapshot(),
+    transcript: Promise.resolve([]),
+    events: { async *[Symbol.asyncIterator]() {} },
+    transcriptBootstrap: {
+      throughSequence: 15,
+      overlayMessageCount: 0,
+      durable: bootstrapPage,
+      overlay: { ...transcriptPage('older', null, 15), source: 'overlay' },
+    },
+    loadTranscriptOverlay: async () => [],
+    decodeTranscriptPage: async (page) => page === bootstrapPage || page === latestPage
+      ? { messages: messages.slice(12, 16), nextCursor: 'older' }
+      : page === historicalPage
+        ? { messages: messages.slice(0, 5), nextCursor: 'newer' }
+        : { messages: messages.slice(6, 11), nextCursor: 'newer' },
+    loadTranscriptPage: async (input) => {
+      requests.push({
+        direction: input.direction,
+        anchorSequence: input.anchorSequence,
+        maxBytes: input.maxBytes,
+      });
+      if (input.direction === 'older') return latestPage;
+      return input.anchorSequence === null ? historicalPage : intermediatePage;
+    },
+    async close() {},
+  });
+  const replica = await DesktopTranscriptReplica.prepare(handle, {
+    generation,
+    onChange: (_current, change) => {
+      for (const batch of encodeDesktopTranscriptChange({
+        sessionId: 'session-1',
+        generation,
+        hostEpoch: 'host-1',
+      }, change)) rendererStore.accept(batch);
+    },
+  });
+  for (const batch of encodeDesktopTranscriptSnapshot(replica.snapshot())) {
+    rendererStore.accept(batch);
+  }
+
+  assert.deepEqual(replica.snapshot().durable.map(({ sequence }) => sequence), [12, 13, 14, 15]);
+  assert.deepEqual(renderedUserPrompts(rendererStore), ['Prompt 7', 'Prompt 8']);
+  assert.equal(rendererStore.range().hasNewer, false);
+  assertRangeFitsBudget(rendererStore);
+
+  await replica.loadAround(0, DESKTOP_TRANSCRIPT_RANGE_MAX_BYTES);
+  assert.deepEqual(replica.snapshot().durable.map(({ sequence }) => sequence), [0, 1, 2, 3, 4]);
+  assert.deepEqual(renderedUserPrompts(rendererStore), ['Prompt 1', 'Prompt 2', 'Prompt 3']);
+  assert.equal(rendererStore.range().hasOlder, false);
+  assert.equal(rendererStore.range().hasNewer, true);
+  assertRangeFitsBudget(rendererStore);
+
+  await replica.loadAround(6, DESKTOP_TRANSCRIPT_RANGE_MAX_BYTES);
+  assert.deepEqual(replica.snapshot().durable.map(({ sequence }) => sequence), [6, 7, 8, 9, 10]);
+  assert.deepEqual(renderedUserPrompts(rendererStore), ['Prompt 4', 'Prompt 5', 'Prompt 6']);
+  assert.equal(rendererStore.range().hasOlder, true);
+  assert.equal(rendererStore.range().hasNewer, true);
+  assertRangeFitsBudget(rendererStore);
+
+  await replica.loadAround(15, DESKTOP_TRANSCRIPT_RANGE_MAX_BYTES);
+  assert.deepEqual(replica.snapshot().durable.map(({ sequence }) => sequence), [12, 13, 14, 15]);
+  assert.deepEqual(renderedUserPrompts(rendererStore), ['Prompt 7', 'Prompt 8']);
+  assert.equal(rendererStore.range().hasOlder, true);
+  assert.equal(rendererStore.range().hasNewer, false);
+  assertRangeFitsBudget(rendererStore);
+
+  assert.deepEqual(requests, [
+    { direction: 'newer', anchorSequence: null, maxBytes: DESKTOP_TRANSCRIPT_RANGE_MAX_BYTES },
+    { direction: 'newer', anchorSequence: 5, maxBytes: DESKTOP_TRANSCRIPT_RANGE_MAX_BYTES },
+    { direction: 'older', anchorSequence: 16, maxBytes: DESKTOP_TRANSCRIPT_RANGE_MAX_BYTES },
+  ]);
+  replica.close();
+});
+
 test('rejects an overlay that exceeds its cache budget', async () => {
   const messages = [
     assistantMessage('x'.repeat(700), 'overlay-1'),
@@ -562,6 +659,43 @@ function transcriptPage(
   };
 }
 
+function syntheticLargeTranscript(): Array<{ identity: number; message: StoredMessage }> {
+  return Array.from({ length: 8 }, (_, index) => {
+    const number = index + 1;
+    const turnId = `turn-${number}`;
+    return [
+      {
+        identity: index * 2,
+        message: {
+          ...userMessage(`Prompt ${number}`, `user-${number}`),
+          turnId,
+        },
+      },
+      {
+        identity: index * 2 + 1,
+        message: {
+          ...assistantMessage('x'.repeat(180 * 1024), `assistant-${number}`),
+          turnId,
+        },
+      },
+    ];
+  }).flat();
+}
+
+function renderedUserPrompts(store: DesktopTranscriptRangeStore): string[] {
+  return store.snapshot().messages.flatMap((message) =>
+    message.type === 'user' ? [message.text] : [],
+  );
+}
+
+function assertRangeFitsBudget(store: DesktopTranscriptRangeStore): void {
+  const bytes = store.snapshot().messages.reduce(
+    (total, message) => total + Buffer.byteLength(JSON.stringify(message), 'utf8'),
+    0,
+  );
+  assert.ok(bytes <= DESKTOP_TRANSCRIPT_RANGE_MAX_BYTES);
+}
+
 function continuitySnapshot() {
   return {
     schemaVersion: SESSION_CONTINUITY_SCHEMA_VERSION,

apps/desktop/src/renderer/chat-message-surface.tsx

@@ -250,6 +250,8 @@ export function ChatMessageSurface({
         historyLoadPending={historyLoadPending}
         onLoadEarlierHistory={onLoadEarlierHistory}
         returnToLatest={hasNewerHistory ? {
+          title: transcriptCopy.partialHistoryTitle,
+          description: transcriptCopy.partialHistoryDescription,
           label: transcriptCopy.returnLatest,
           isPending: historyLoadPending,
           onClick: onReturnToLatestHistory,

apps/desktop/src/renderer/locales/conversation-copy.ts

@@ -56,6 +56,8 @@ export interface DesktopConversationCopy {
     modelReboundTitle: string;
     modelReboundDescription: (modelId?: string) => string;
     messageReadFailedTitle: string;
+    partialHistoryTitle: string;
+    partialHistoryDescription: string;
     returnLatest: string;
     scrollMainToBottom: string;
   };
@@ -416,7 +418,7 @@ function enDetail(parts: readonly string[]): string {
 
 const COPY = {
   zh: {
-    actions: { stopFailedTitle: '停止失败', stopFailedFallback: '任务操作失败，请稍后重试。', refreshSessionsFailedTitle: '刷新任务列表失败', refreshSessionsFailedFallback: '刷新任务列表失败，请稍后重试。', conversationErrorTitle: '任务出错', conversationErrorFallback: '任务运行失败，请稍后重试。', regenerateStartedTitle: '已发起重新生成', regenerateStartedDescription: '正在生成新的一轮回答', branchCreatedTitle: '已创建分支', branchCreatedDescription: (name) => `新任务 ${name}`, revisionStartedTitle: '已创建修改版草稿', revisionStartedDescription: '原任务仍会保留；修改后发送将在新版本中继续', revisionReadyTitle: '可以修改并重发了', revisionReadyDescription: '已回到该消息之前；编辑后发送即可', revisionUnavailableTitle: '暂时无法编辑这条消息', revisionAttachmentsUnsupported: '包含附件的历史消息暂不支持编辑并重发，请复制文字后新建消息。', revisionTransformedTextUnsupported: '通过显式技能发送的历史消息暂不支持编辑并重发，请复制文字后重新选择技能。', revisionDraftAttachmentConflict: 'Composer 中已有待发送附件，请先发送或移除附件，再编辑历史消息。', revisionCommandUnsupported: '修改消息时不能执行 /compact、/side 或编排命令，请取消修改后再试。', revisionAlreadyActive: '已有一条消息正在修改，请先发送或取消当前修改。', revisionCancelLabel: '取消', revisionBannerTitle: '正在修改已发送消息', revisionBannerDetail: '· 发送后创建新版本', revisionUnchanged: '内容没有变化。如需重新回答，请使用“重新生成”。', operationFailedTitle: '操作失败', operationFailedFallback: '任务操作失败，请稍后重试。', attachmentFailedTitle: '添加附件失败', tryAgain: '请稍后重试。', modelReboundTitle: '已切换到可用模型', modelReboundDescription: (modelId) => `原任务使用的连接已不可用${modelId ? ` · ${modelId}` : ''}`, messageReadFailedTitle: '读取任务失败', returnLatest: '返回最新消息', scrollMainToBottom: '滚动主对话到底部' },
+    actions: { stopFailedTitle: '停止失败', stopFailedFallback: '任务操作失败，请稍后重试。', refreshSessionsFailedTitle: '刷新任务列表失败', refreshSessionsFailedFallback: '刷新任务列表失败，请稍后重试。', conversationErrorTitle: '任务出错', conversationErrorFallback: '任务运行失败，请稍后重试。', regenerateStartedTitle: '已发起重新生成', regenerateStartedDescription: '正在生成新的一轮回答', branchCreatedTitle: '已创建分支', branchCreatedDescription: (name) => `新任务 ${name}`, revisionStartedTitle: '已创建修改版草稿', revisionStartedDescription: '原任务仍会保留；修改后发送将在新版本中继续', revisionReadyTitle: '可以修改并重发了', revisionReadyDescription: '已回到该消息之前；编辑后发送即可', revisionUnavailableTitle: '暂时无法编辑这条消息', revisionAttachmentsUnsupported: '包含附件的历史消息暂不支持编辑并重发，请复制文字后新建消息。', revisionTransformedTextUnsupported: '通过显式技能发送的历史消息暂不支持编辑并重发，请复制文字后重新选择技能。', revisionDraftAttachmentConflict: 'Composer 中已有待发送附件，请先发送或移除附件，再编辑历史消息。', revisionCommandUnsupported: '修改消息时不能执行 /compact、/side 或编排命令，请取消修改后再试。', revisionAlreadyActive: '已有一条消息正在修改，请先发送或取消当前修改。', revisionCancelLabel: '取消', revisionBannerTitle: '正在修改已发送消息', revisionBannerDetail: '· 发送后创建新版本', revisionUnchanged: '内容没有变化。如需重新回答，请使用“重新生成”。', operationFailedTitle: '操作失败', operationFailedFallback: '任务操作失败，请稍后重试。', attachmentFailedTitle: '添加附件失败', tryAgain: '请稍后重试。', modelReboundTitle: '已切换到可用模型', modelReboundDescription: (modelId) => `原任务使用的连接已不可用${modelId ? ` · ${modelId}` : ''}`, messageReadFailedTitle: '读取任务失败', partialHistoryTitle: '正在查看较早的一段对话', partialHistoryDescription: '较新的消息仍已保存，但当前未加载。', returnLatest: '返回最新消息', scrollMainToBottom: '滚动主对话到底部' },
     attachments: { tooMany: '附件数量超过 8 个', tooLarge: '附件大小超过 50MB', duplicate: '附件来源重复，请勿重复添加同一文件。' },
     model: {
       fakeBackendLabel: '本地模拟连接',
@@ -641,7 +643,7 @@ const COPY = {
     turnError: { unknown: '未知错误', contextOverflow: '上下文窗口已超出限制', contextBudgetExhausted: '上下文已达到上限，当前任务无法继续', malformedSummary: '上下文压缩未能生成有效摘要。请检查模型的上下文窗口设置、切换模型，或开启新任务。', timeout: '请求超时', auth: '鉴权失败', providerBilling: '模型服务计费受限', providerCapacity: '模型服务暂时满载，请稍后重试或切换模型', rateLimit: '触发模型速率限制', network: '网络错误', provider: '模型服务返回错误', stepCap: '达到工具步骤上限', tool: '工具调用失败', permission: '等待权限确认', restarted: '本地应用重启，上一轮没有完成', sandboxBoundaryClosed: '本地应用重启，等待确认的「允许访问工作区以外的内容」请求已按拒绝关闭', recovery: { safeResume: '检查当前状态后，可尝试安全恢复', stepCap: '任务可能尚未完成，可以继续', toolError: '先检查工具结果，再决定是否重试', connection: '先检查模型连接或登录状态', partial: '已保留部分输出，可从这里继续', toolRecord: '工具记录已保留，重试前先看结果', retry: '没有执行工具，可直接重试', capacity: '模型服务暂时满载，请等待几分钟或切换模型后重试', contextOverflow: '上下文仍超出限制，请减少附件或开启新任务', contextBudgetExhausted: '检查模型的上下文窗口设置、切换模型，或开启新任务', sandboxBoundaryClosed: '访问范围没有放开，重试本轮后可重新决定' } },
   },
   en: {
-    actions: { stopFailedTitle: 'Failed to stop', stopFailedFallback: 'The task action failed. Try again later.', refreshSessionsFailedTitle: 'Failed to refresh tasks', refreshSessionsFailedFallback: 'The task list could not be refreshed. Try again later.', conversationErrorTitle: 'Task error', conversationErrorFallback: 'The task run failed. Try again later.', regenerateStartedTitle: 'Regeneration started', regenerateStartedDescription: 'Generating a new response', branchCreatedTitle: 'Branch created', branchCreatedDescription: (name) => `New task: ${name}`, revisionStartedTitle: 'Edit draft ready', revisionStartedDescription: 'The original task is kept; sending creates a new version', revisionReadyTitle: 'Ready to edit and resend', revisionReadyDescription: 'Rewound to before that message; edit and send when ready', revisionUnavailableTitle: 'This message cannot be edited yet', revisionAttachmentsUnsupported: 'Edit & resend does not yet support historical attachments. Copy the text into a new message instead.', revisionTransformedTextUnsupported: 'Edit & resend does not yet support messages sent with an explicit skill. Copy the text and select the skill again instead.', revisionDraftAttachmentConflict: 'The composer already has pending attachments. Send or remove them before editing a sent message.', revisionCommandUnsupported: 'You cannot run /compact, /side, or orchestration commands while editing a sent message. Cancel the edit first.', revisionAlreadyActive: 'Another message is already being edited. Send or cancel that edit first.', revisionCancelLabel: 'Cancel', revisionBannerTitle: 'Editing sent message', revisionBannerDetail: '· New version on send', revisionUnchanged: 'Nothing changed. Use Regenerate if you only want a new answer.', operationFailedTitle: 'Action failed', operationFailedFallback: 'The task action failed. Try again later.', attachmentFailedTitle: 'Failed to add attachment', tryAgain: 'Try again later.', modelReboundTitle: 'Switched to an available model', modelReboundDescription: (modelId) => `The previous connection is unavailable${modelId ? ` · ${modelId}` : ''}`, messageReadFailedTitle: 'Failed to load task', returnLatest: 'Return to latest', scrollMainToBottom: 'Scroll main conversation to bottom' },
+    actions: { stopFailedTitle: 'Failed to stop', stopFailedFallback: 'The task action failed. Try again later.', refreshSessionsFailedTitle: 'Failed to refresh tasks', refreshSessionsFailedFallback: 'The task list could not be refreshed. Try again later.', conversationErrorTitle: 'Task error', conversationErrorFallback: 'The task run failed. Try again later.', regenerateStartedTitle: 'Regeneration started', regenerateStartedDescription: 'Generating a new response', branchCreatedTitle: 'Branch created', branchCreatedDescription: (name) => `New task: ${name}`, revisionStartedTitle: 'Edit draft ready', revisionStartedDescription: 'The original task is kept; sending creates a new version', revisionReadyTitle: 'Ready to edit and resend', revisionReadyDescription: 'Rewound to before that message; edit and send when ready', revisionUnavailableTitle: 'This message cannot be edited yet', revisionAttachmentsUnsupported: 'Edit & resend does not yet support historical attachments. Copy the text into a new message instead.', revisionTransformedTextUnsupported: 'Edit & resend does not yet support messages sent with an explicit skill. Copy the text and select the skill again instead.', revisionDraftAttachmentConflict: 'The composer already has pending attachments. Send or remove them before editing a sent message.', revisionCommandUnsupported: 'You cannot run /compact, /side, or orchestration commands while editing a sent message. Cancel the edit first.', revisionAlreadyActive: 'Another message is already being edited. Send or cancel that edit first.', revisionCancelLabel: 'Cancel', revisionBannerTitle: 'Editing sent message', revisionBannerDetail: '· New version on send', revisionUnchanged: 'Nothing changed. Use Regenerate if you only want a new answer.', operationFailedTitle: 'Action failed', operationFailedFallback: 'The task action failed. Try again later.', attachmentFailedTitle: 'Failed to add attachment', tryAgain: 'Try again later.', modelReboundTitle: 'Switched to an available model', modelReboundDescription: (modelId) => `The previous connection is unavailable${modelId ? ` · ${modelId}` : ''}`, messageReadFailedTitle: 'Failed to load task', partialHistoryTitle: 'Viewing an earlier part of this conversation', partialHistoryDescription: 'Newer messages are still saved, but are not currently loaded.', returnLatest: 'Return to latest', scrollMainToBottom: 'Scroll main conversation to bottom' },
     attachments: { tooMany: 'You can attach at most 8 files', tooLarge: 'Attachments must be 50 MB or smaller', duplicate: 'This attachment was already added.' },
     model: {
       fakeBackendLabel: 'Local simulation',

apps/desktop/src/renderer/styles/chat-message.css

@@ -319,7 +319,32 @@
 }
 .maka-transcript-history-controls {
   display: flex;
-  justify-content: center;
-  gap: 8px;
-  padding: 8px 0;
+  box-sizing: border-box;
+  align-items: center;
+  justify-content: space-between;
+  flex-wrap: wrap;
+  gap: var(--space-2) var(--space-4);
+  margin: var(--space-2) clamp(var(--space-3), 4vw, var(--space-10));
+  padding: var(--space-2) var(--space-3);
+  border: var(--border-width-hairline) solid var(--border-soft);
+  border-radius: var(--radius-element);
+  background: var(--surface-raised);
+}
+
+.maka-transcript-history-copy {
+  display: flex;
+  min-width: min(100%, 28rem);
+  flex: 1 1 28rem;
+  flex-direction: column;
+  gap: var(--space-0-5);
+}
+
+.maka-transcript-history-title {
+  font: var(--maka-text-label);
+  color: var(--foreground);
+}
+
+.maka-transcript-history-description {
+  font: var(--maka-text-supporting);
+  color: var(--muted-foreground);
 }