feat(ui): add ui.history.collapsePreviewCount to show last N turns when resuming collapsed sessions

docs/users/configuration/settings.md

@@ -116,6 +116,7 @@ Settings are organized into categories. Most settings should be placed within th
 | `ui.renderMode`                         | string           | Default Markdown display mode. Use `"render"` for rich visual previews or `"raw"` to show source-oriented Markdown by default. Toggle during a session with `Alt/Option+M`; on macOS the terminal must send Option as Meta. See [Markdown Rendering](../features/markdown-rendering).                                                                                                                                                                                                                                                              | `"render"`    |
 | `ui.showCitations`                      | boolean          | Show citations for generated text in the chat.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | `false`       |
 | `ui.history.collapseOnResume`           | boolean          | Whether to collapse history by default when resuming a session. Can be toggled via `/history collapse-on-resume` and `/history expand-on-resume`.                                                                                                                                                                                                                                                                                                                                                                                                  | `false`       |
+| `ui.history.collapsePreviewCount`       | number           | Number of most recent user turns to keep visible when `ui.history.collapseOnResume` is enabled. `0` collapses all restored history by default; `-1` shows all restored history.                                                                                                                                                                                                                                                                                                                                                                      | `0`           |
 | `ui.compactMode`                        | boolean          | Hide tool output and thinking for a cleaner view. Toggle with `Ctrl+O` during a session or via the Settings dialog. Tool approval prompts are never hidden, even in compact mode. The setting persists across sessions.                                                                                                                                                                                                                                                                                                                            | `false`       |
 | `ui.shellOutputMaxLines`                | number           | Max number of shell output lines shown inline. Set to `0` to disable the cap and show full output. Hidden lines are surfaced via the `+N lines` indicator. Errors, `!`-prefix user-initiated commands, confirming tools, and focused embedded shells always show full output.                                                                                                                                                                                                                                                                      | `5`           |
 | `ui.enableWelcomeBack`                  | boolean          | Show welcome back dialog when returning to a project with conversation history. When enabled, Qwen Code will automatically detect if you're returning to a project with a previously generated project summary (`.qwen/PROJECT_SUMMARY.md`) and show a dialog allowing you to continue your previous conversation or start fresh. If you choose **Start new chat session**, that choice is remembered for the current project until the project summary changes. This feature integrates with the `/summary` command and quit confirmation dialog. | `true`        |

packages/cli/src/config/settingsSchema.ts

@@ -842,6 +842,16 @@ const SETTINGS_SCHEMA = {
               'Whether to collapse history by default when resuming a session.',
             showInDialog: false,
           },
+          collapsePreviewCount: {
+            type: 'number',
+            label: 'Collapse Preview Count',
+            category: 'UI',
+            requiresRestart: false,
+            default: 0,
+            description:
+              'Number of most recent user turns to keep visible when collapsing history on resume. 0 collapses all restored history by default; -1 shows all restored history.',
+            showInDialog: false,
+          },
         },
       },
       showLineNumbers: {

packages/cli/src/ui/AppContainer.tsx

@@ -629,10 +629,13 @@ export const AppContainer = (props: AppContainerProps) => {
         const rawItems = buildResumedHistoryItems(resumedSessionData, config);
         const collapseOnResume =
           settings.merged.ui?.history?.collapseOnResume ?? false;
+        const collapsePreviewCount =
+          settings.merged.ui?.history?.collapsePreviewCount ?? 0;
 
         const historyItems = applyCollapsePolicyAndSummary(
           rawItems,
           collapseOnResume,
+          collapsePreviewCount,
         );
         historyManager.loadHistory(historyItems);
 

packages/cli/src/ui/hooks/useBranchCommand.ts

@@ -157,9 +157,12 @@ export function useBranchCommand(
         const rawItems = buildResumedHistoryItems(resumed, config);
         const collapseOnResume =
           options.settings.merged.ui?.history?.collapseOnResume ?? false;
+        const collapsePreviewCount =
+          options.settings.merged.ui?.history?.collapsePreviewCount ?? 0;
         const uiHistoryItems = applyCollapsePolicyAndSummary(
           rawItems,
           collapseOnResume,
+          collapsePreviewCount,
         );
         startNewSession(newSessionId);
         historyManager.clearItems();
@@ -276,6 +279,7 @@ export function useBranchCommand(
       setSessionName,
       remount,
       options.settings.merged.ui?.history?.collapseOnResume,
+      options.settings.merged.ui?.history?.collapsePreviewCount,
     ],
   );
 

packages/cli/src/ui/hooks/useResumeCommand.ts

@@ -123,10 +123,13 @@ export function useResumeCommand(
         const rawItems = buildResumedHistoryItems(sessionData, config);
         const collapseOnResume =
           settings.merged.ui?.history?.collapseOnResume ?? false;
+        const collapsePreviewCount =
+          settings.merged.ui?.history?.collapsePreviewCount ?? 0;
 
         const uiHistoryItems = applyCollapsePolicyAndSummary(
           rawItems,
           collapseOnResume,
+          collapsePreviewCount,
         );
 
         // 1. Swap core first. Matches useBranchCommand's core-before-UI
@@ -218,6 +221,7 @@ export function useResumeCommand(
       setSessionName,
       remount,
       settings.merged.ui?.history?.collapseOnResume,
+      settings.merged.ui?.history?.collapsePreviewCount,
     ],
   );
 

packages/cli/src/ui/utils/resumeHistoryUtils.test.ts

@@ -6,11 +6,12 @@
 
 import { describe, it, expect, vi, beforeEach } from 'vitest';
 import {
+  applyCollapsePolicyAndSummary,
   buildResumedHistoryItems,
   stripSuppressOnRestore,
   expandCollapsedHistory,
 } from './resumeHistoryUtils.js';
-import { ToolCallStatus } from '../types.js';
+import { MessageType, ToolCallStatus } from '../types.js';
 import type {
   AnyDeclarativeTool,
   Config,
@@ -496,6 +497,88 @@ describe('resumeHistoryUtils', () => {
   });
 });
 
+describe('applyCollapsePolicyAndSummary', () => {
+  const makeItems = (): HistoryItem[] =>
+    [
+      { id: 1, type: MessageType.USER, text: 'first' },
+      { id: 2, type: MessageType.GEMINI, text: 'first response' },
+      { id: 3, type: MessageType.USER, text: 'second' },
+      { id: 4, type: MessageType.GEMINI, text: 'second response' },
+      { id: 5, type: MessageType.USER, text: 'third' },
+      { id: 6, type: MessageType.GEMINI, text: 'third response' },
+    ] as HistoryItem[];
+
+  const expectSuppressed = (item: HistoryItem) => {
+    expect(item.display).toEqual(
+      expect.objectContaining({ suppressOnRestore: true }),
+    );
+  };
+
+  const expectVisible = (item: HistoryItem) => {
+    expect(item.display?.suppressOnRestore).toBeUndefined();
+  };
+
+  it('suppresses all items and shows the full summary count by default', () => {
+    const result = applyCollapsePolicyAndSummary(makeItems(), true);
+
+    expect(result).toHaveLength(7);
+    result.slice(0, 6).forEach(expectSuppressed);
+    expect(result[6]).toEqual(
+      expect.objectContaining({
+        id: 7,
+        type: MessageType.INFO,
+        text: expect.stringContaining('6 messages hidden'),
+        display: { kind: 'collapse-summary' },
+      }),
+    );
+  });
+
+  it('keeps the most recent N user turns visible and summarizes only hidden items', () => {
+    const result = applyCollapsePolicyAndSummary(makeItems(), true, 2);
+
+    expect(result).toHaveLength(7);
+    result.slice(0, 2).forEach(expectSuppressed);
+    result.slice(2, 6).forEach(expectVisible);
+    expect(result[6]).toEqual(
+      expect.objectContaining({
+        id: 7,
+        type: MessageType.INFO,
+        text: expect.stringContaining('2 messages hidden'),
+        display: { kind: 'collapse-summary' },
+      }),
+    );
+  });
+
+  it('shows all items without a summary when preview count covers all user turns', () => {
+    const rawItems = makeItems();
+    const result = applyCollapsePolicyAndSummary(rawItems, true, 3);
+
+    expect(result).toEqual(rawItems);
+    expect(
+      result.some((item) => item.display?.kind === 'collapse-summary'),
+    ).toBe(false);
+    result.forEach(expectVisible);
+  });
+
+  it('shows all items without a summary when preview count is -1', () => {
+    const rawItems = makeItems();
+    const result = applyCollapsePolicyAndSummary(rawItems, true, -1);
+
+    expect(result).toBe(rawItems);
+  });
+
+  it('returns raw items unchanged when collapseOnResume is false', () => {
+    const rawItems = makeItems();
+    const result = applyCollapsePolicyAndSummary(rawItems, false, 1);
+
+    expect(result).toBe(rawItems);
+  });
+
+  it('returns empty history without a summary', () => {
+    expect(applyCollapsePolicyAndSummary([], true)).toEqual([]);
+  });
+});
+
 describe('stripSuppressOnRestore', () => {
   it('returns item unchanged when display is undefined', () => {
     const item = { id: 1, type: 'user', text: 'hello' } as HistoryItem;

packages/cli/src/ui/utils/resumeHistoryUtils.ts

@@ -568,16 +568,37 @@ export function expandCollapsedHistory(items: HistoryItem[]): HistoryItem[] {
 export function applyCollapsePolicyAndSummary(
   rawItems: HistoryItem[],
   collapseOnResume: boolean,
+  collapsePreviewCount: number = 0,
 ): HistoryItem[] {
   if (!collapseOnResume) return rawItems;
+  if (collapsePreviewCount === -1) return rawItems;
+
+  let boundary = rawItems.length;
+  if (collapsePreviewCount > 0) {
+    let userTurnCount = 0;
+    for (let i = rawItems.length - 1; i >= 0; i--) {
+      if (rawItems[i].type === MessageType.USER) {
+        userTurnCount++;
+        if (userTurnCount === collapsePreviewCount) {
+          boundary = i;
+          break;
+        }
+      }
+    }
+    if (userTurnCount < collapsePreviewCount) {
+      boundary = 0;
+    }
+  }
 
-  const uiHistoryItems = applyResumeDisplayPolicy(rawItems);
+  const hiddenItems = applyResumeDisplayPolicy(rawItems.slice(0, boundary));
+  const visibleItems = rawItems.slice(boundary);
+  const uiHistoryItems = [...hiddenItems, ...visibleItems];
 
-  if (rawItems.length > 0) {
+  if (boundary > 0) {
     const nextId = rawItems[rawItems.length - 1].id + 1;
     return [
       ...uiHistoryItems,
-      { id: nextId, ...createHistoryCollapseSummaryItem(rawItems.length) },
+      { id: nextId, ...createHistoryCollapseSummaryItem(boundary) },
     ];
   }
 

packages/vscode-ide-companion/schemas/settings.schema.json

@@ -278,6 +278,11 @@
               "description": "Whether to collapse history by default when resuming a session.",
               "type": "boolean",
               "default": false
+            },
+            "collapsePreviewCount": {
+              "description": "Number of most recent user turns to keep visible when collapsing history on resume. 0 collapses all restored history by default; -1 shows all restored history.",
+              "type": "number",
+              "default": 0
             }
           }
         },