perf(desktop): bound rendering within oversized turns

apps/desktop/e2e/fixtures.ts

@@ -483,7 +483,9 @@ async function withE2eWindow(
  });
  let page: Page;
  try {
- page = await app.firstWindow();
+ // Parallel CI workers and cold Windows hosts can finish process launch
+ // before the first BrowserWindow crosses Playwright's 30s default.
+ page = await app.firstWindow({ timeout: 60_000 });
  } catch (error) {
  const detail = error instanceof Error ? error.message : String(error);
  const logs = mainLogs.length > 0 ? `\nElectron main console:\n${mainLogs.join('\n')}` : '';
@@ -514,7 +516,12 @@ async function withE2eWindow(
  try {
  if (app) await closeElectronApplication(app, 5_000);
  } finally {
- await rm(userDataDir, { recursive: true, force: true });
+ await rm(userDataDir, {
+ recursive: true,
+ force: true,
+ maxRetries: 5,
+ retryDelay: 100,
+ });
  }
  }
 }
@@ -573,6 +580,7 @@ type E2eTestFixtures = {
  promptRailWindow: Page;
  threadSearchWindow: Page;
  partialHistoryWindow: Page;
+ oversizedTurnWindow: Page;
  requestHeaderRowWindow: Page;
  permissionCenterWindow: Page;
  newTaskTargetWindow: Page;
@@ -777,6 +785,17 @@ export const test = base.extend<E2eTestFixtures, E2eWorkerFixtures>({
  showWindow: true,
  }, use);
  },
+ // One Turn larger than the transcript byte budget. Shown because the test
+ // reads Chromium's actual content-visibility state while crossing it.
+ oversizedTurnWindow: async ({}, use) => {
+ await withE2eWindow({
+ seed: false,
+ readinessSelector: '[data-turn-id="turn-oversized-fixture"]',
+ e2eFixtureScenario: 'chat-oversized-turn',
+ locale: 'zh',
+ showWindow: true,
+ }, use);
+ },
  // Settings → 模型, where `no-models` is the seeded openai-compatible relay —
  // the connection type whose detail page owns the custom request headers
  // editor. Shown, because what this window is for is a rendered box

apps/desktop/e2e/oversized-turn-render.spec.ts

@@ -0,0 +1,52 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { expect, test } from './fixtures';
+
+const SEGMENT = '[data-maka-transcript-boundary]';
+
+test('an oversized single Turn skips offscreen timeline blocks', async ({
+ oversizedTurnWindow: page,
+}) => {
+ await page.setViewportSize({ width: 900, height: 700 });
+ const segments = page.locator(SEGMENT);
+ await expect(segments).not.toHaveCount(0);
+ expect(await segments.count()).toBeGreaterThan(80);
+
+ const state = await segments.evaluateAll((elements) => {
+ const rows = elements as HTMLElement[];
+ return {
+ automatic: rows.filter((element) =>
+ getComputedStyle(element).contentVisibility === 'auto').length,
+ skipped: rows.filter((element) =>
+ !element.checkVisibility({ contentVisibilityAuto: true })).length,
+ };
+ });
+ expect(state.automatic).toBe(await segments.count());
+ expect(state.skipped).toBeGreaterThan(0);
+
+ const first = segments.first();
+ await first.evaluate((element) => element.scrollIntoView({ block: 'center' }));
+ await page.evaluate(() => new Promise<void>((resolve) =>
+ requestAnimationFrame(() => requestAnimationFrame(() => resolve())),
+ ));
+ expect(await first.evaluate((element) =>
+ element.checkVisibility({ contentVisibilityAuto: true }),
+ )).toBe(true);
+});

apps/desktop/src/main/e2e-fixture.ts

@@ -40,6 +40,7 @@ import {
  LONG_SIDEBAR_PROJECT_ID,
  LONG_SIDEBAR_PROJECT_NAME,
  LONG_SIDEBAR_SESSION_PREFIX,
+ OVERSIZED_TURN_SESSION_ID,
  PARTIAL_HISTORY_SESSION_ID,
  PROMPT_RAIL_SESSION_ID,
  AGENT_GRAPH_SESSION_ID,
@@ -49,6 +50,8 @@ import {
 import {
  partialHistoryMessages,
  partialHistorySession,
+ oversizedTurnMessages,
+ oversizedTurnSession,
  promptRailMessages,
  promptRailSession,
  turnMessages,
@@ -71,6 +74,7 @@ const E2E_FIXTURE_SCENARIOS = new Set<E2eFixtureScenario>([
  'turn-narrative-browser',
  'chat-prompt-rail',
  'chat-partial-history',
+ 'chat-oversized-turn',
  'settings-data',
  'settings-bots-onboarding',
  'settings-general',
@@ -191,6 +195,8 @@ export function getE2eFixtureState(fixture: E2eFixture | null): E2eFixtureState
  return { ...state, activeSessionId: PROMPT_RAIL_SESSION_ID, workbarCollapsed: true };
  case 'chat-partial-history':
  return { ...state, activeSessionId: PARTIAL_HISTORY_SESSION_ID, workbarCollapsed: true };
+ case 'chat-oversized-turn':
+ return { ...state, activeSessionId: OVERSIZED_TURN_SESSION_ID, workbarCollapsed: true };
  case 'settings-data':
  return { ...state, activeSessionId: TURN_SESSION_ID, openSettingsSection: 'data' };
  case 'settings-bots-onboarding':
@@ -276,6 +282,13 @@ export async function seedE2eFixture(input: {
  partialHistoryMessages(now),
  );
  }
+ if (scenario === 'chat-oversized-turn') {
+ await writeSession(
+ input.workspaceRoot,
+ oversizedTurnSession(now),
+ oversizedTurnMessages(now),
+ );
+ }
  if (scenario === 'sidebar-search-modal-open') {
  for (const seed of longSidebarSessions(now)) {
  await writeSession(input.workspaceRoot, seed.header, seed.messages);

apps/desktop/src/main/e2e-fixture/scenarios-chat.ts

@@ -21,6 +21,7 @@ import type { SessionHeader, StoredMessage } from '@maka/core/session';
 import {
  header,
  AGENT_GRAPH_SESSION_ID,
+ OVERSIZED_TURN_SESSION_ID,
  PARTIAL_HISTORY_SESSION_ID,
  PROMPT_RAIL_PROMPT_COUNT,
  PROMPT_RAIL_SESSION_ID,
@@ -201,3 +202,101 @@ export function partialHistoryMessages(now: number): StoredMessage[] {
  }
  return messages;
 }
+
+export function oversizedTurnSession(now: number): SessionHeader {
+ return header({
+ id: OVERSIZED_TURN_SESSION_ID,
+ name: '单轮超长渲染边界示例',
+ connection: 'zai-live',
+ model: 'glm-5.1',
+ now,
+ lastMessageAt: now - 60_000,
+ });
+}
+
+/**
+ * One synthetic Turn that exceeds the Desktop transcript byte budget by
+ * itself. Alternating answers and tool evidence create many stable visual
+ * blocks inside the same Turn, reproducing the shape that whole-Turn
+ * containment cannot bound without carrying any real conversation data.
+ */
+export function oversizedTurnMessages(now: number): StoredMessage[] {
+ const turnId = 'turn-oversized-fixture';
+ const messages: StoredMessage[] = [{
+ type: 'user',
+ id: 'msg-oversized-user',
+ turnId,
+ ts: now - 10 * 60_000,
+ text: '检查一组独立的合成步骤，并逐项给出简短结果。',
+ }];
+ const prose = [
+ '这一段只包含确定性的合成文本，用于测量长对话的滚动渲染。',
+ '',
+ '- 已检查输入边界',
+ '- 已记录合成结果',
+ '- 下一步继续验证',
+ ].join('\n');
+ const toolOutput = 'synthetic output line\n'.repeat(600);
+ // Reasoning is the block #4256 reports as the dominant cost, and it is unlike
+ // collapsed tool output: `ChatReasoning` keeps its body mounted and only swaps
+ // a wrapper class, so a folded reasoning run still lays out. Give each step a
+ // multi-paragraph run so the `.maka-deep-thinking` boundary carries real,
+ // mounted content rather than free collapsed-stdout bytes.
+ const reasoning = [
+ '先确认这一步的输入边界：空样例、超长样例、并发样例三类分别对照期望结果，',
+ '逐项记录偏差，再对合成输出做一次去抖动检查，确保占位高度不随展开态漂移。',
+ '',
+ '- 输入域：空 / 超长 / 并发',
+ '- 期望：确定性、可重放',
+ '- 检查：占位高度稳定，无跨帧跳变',
+ '',
+ '综合以上，本步没有回归，可以进入下一组合成检查。',
+ ].join('\n');
+ for (let index = 1; index <= 48; index += 1) {
+ const ts = now - (49 - index) * 10_000;
+ messages.push({
+ type: 'assistant',
+ id: `msg-oversized-assistant-${index}`,
+ turnId,
+ ts,
+ text: `### 合成步骤 ${index}\n\n${prose.repeat(12)}`,
+ thinking: { text: `${reasoning}\n\n${reasoning}\n\n${reasoning}` },
+ modelId: 'glm-5.1',
+ });
+ messages.push({
+ type: 'tool_call',
+ id: `tool-oversized-${index}`,
+ turnId,
+ ts: ts + 1_000,
+ toolName: 'Bash',
+ displayName: `合成检查 ${index}`,
+ intent: `读取第 ${index} 组固定测试数据`,
+ args: { cmd: `fixture-check --step ${index}`, cwd: '/workspace/maka' },
+ });
+ messages.push({
+ type: 'tool_result',
+ id: `tool-oversized-result-${index}`,
+ turnId,
+ ts: ts + 2_000,
+ toolUseId: `tool-oversized-${index}`,
+ isError: false,
+ durationMs: 100 + index,
+ content: {
+ kind: 'terminal',
+ cwd: '/workspace/maka',
+ cmd: `fixture-check --step ${index}`,
+ status: 'completed',
+ exitCode: 0,
+ output: {
+ mode: 'pipes',
+ stdout: toolOutput,
+ stderr: '',
+ stdoutTruncated: false,
+ stderrTruncated: false,
+ redacted: false,
+ },
+ },
+ });
+ }
+ return messages;
+}

apps/desktop/src/main/e2e-fixture/seed-helpers.ts

@@ -36,6 +36,7 @@ export const TURN_SESSION_ID = 'e2e-fixture-turn';
 export const AGENT_GRAPH_SESSION_ID = 'e2e-fixture-agent-graph';
 export const PROMPT_RAIL_SESSION_ID = 'e2e-fixture-prompt-rail';
 export const PARTIAL_HISTORY_SESSION_ID = 'e2e-fixture-partial-history';
+export const OVERSIZED_TURN_SESSION_ID = 'e2e-fixture-oversized-turn';
 /** Exceeds both the 64-tick rail and the bounded active transcript range. */
 export const PROMPT_RAIL_PROMPT_COUNT = 120;
 export const LONG_SIDEBAR_SESSION_PREFIX = 'e2e-fixture-sidebar-long-';

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

@@ -123,6 +123,35 @@
  gap: var(--space-1);
 }
 
+/* A transcript range is bounded by complete Turns, so one unusually large
+ Turn can still be much taller than the scrollport. The outer Turn's
+ content-visibility boundary stops helping as soon as any part of that Turn
+ becomes relevant. Keep the stable timeline blocks inside it independently
+ skippable so Chromium does not lay out and paint every Markdown, reasoning,
+ and tool subtree while the reader crosses one nearby block.
+
+ Renderers apply the marker at the source of each timeline block, including
+ the children of a Processing fold. `auto` retains the measured block size
+ after first paint, preserving native scroll
+ anchoring when a skipped block leaves and re-enters the viewport. */
+.maka-chat-message-list [data-maka-transcript-boundary] {
+ content-visibility: auto;
+ /* First-paint intrinsic-size ESTIMATE for scroll-anchor stability, not a
+ fixed height: `auto <n>px` still grows to the block's real size after
+ paint. 96px is the single-line answer baseline; tall multi-line blocks
+ override it below. */
+ contain-intrinsic-block-size: auto 96px;
+}
+
+/* Reasoning runs, Processing children, linked-agent lists, and tool/activity
+ cards are routinely multi-line. Their 320px first-paint estimate lets native
+ overflow anchoring absorb more of the intrinsic-size correction. It remains
+ an estimate rather than a clamp: the block grows to its measured size after
+ paint. */
+.maka-chat-message-list [data-maka-transcript-boundary="large"] {
+ contain-intrinsic-block-size: auto 320px;
+}
+
 /* Expanded activity headers stay reachable while their own detail is being
  read. Native sticky positioning keeps the header in the transcript flow,
  so it leaves naturally at the card boundary and does not disturb ChatLayout