fix: rebuild collapsed content across native scrollback

packages/tui/src/tui/engine/LOCAL_CHANGES.json

@@ -163,8 +163,8 @@
     },
     {
       "path": "tui-main-screen.ts",
-      "currentSha256": "146fd4222ae5a48d1f439de2f280b111789151a30c1bdd2735e32fff07329b9d",
-      "changeIds": ["L005", "L017", "L027", "L033", "L034"],
+      "currentSha256": "6970c4bac059263fc1ec420fa07362b7bcc1838fd381dbaa5a61180c15bb4787",
+      "changeIds": ["L005", "L017", "L027", "L033", "L034", "L036"],
       "upstreamCommit": "6c4f360264397c59801f6da2bdac13e3b1fcbe91",
       "reason": "Keep strict TypeScript fixes and stream full and differential renders through Pi's bounded terminal writer. 缩放期间仅重绘可见尾部 常规模式在差分比较前剥离行首 OSC 133 zone 标记。 内容收缩或历史内容变化触发回退重绘时仅更新可见区域。",
       "behaviorImpact": "Large regular-mode renders preserve output order without constructing a single V8-limited terminal string. 150ms 后及退出前重放完整投影历史。 内部导航标记不再写入终端，避免 iTerm2 左侧箭头和命令条噪声。 Session 结束后的状态更新不再发送 ESC 3J 清除原生滚动历史，当前视口仍显示最新内容。"

packages/tui/src/tui/engine/LOCAL_CHANGES.md

@@ -115,3 +115,11 @@ Remove `L024` when the selected Pi baseline natively matches legacy-terminal `Ct
 - Adaptation: the original contribution widened hits over two live content columns. The reserved gutter prevents those presses from swallowing content clicks or text selection. `chat-layout.ts` opts into the three-column gutter.
 - Evidence: `test/unit/tui-scrollbar-interaction.test.ts` drives SGR press, motion, release and wheel events through VirtualTerminal, covering track jumps, thumb grabs, narrow terminals, content routing, selection, overlays and the actual fullscreen ChatLayout.
 - Removal condition: the selected Pi baseline provides equivalent reserved-gutter track and drag interaction and MCode migrates to it.
+
+## L036: Rebuild structural collapses across native scrollback
+
+- Origin: follow-up to [PR #243](https://github.com/MiniMax-AI/minimax-code/pull/243).
+- Product contract: collapsing transient content must retain the folded summary and every Composer row, even when they move above the previous viewport origin.
+- Minimal difference: during a shrinking viewport-only redraw, compare the text of the scrolled prefix after stripping terminal sequences. If that prefix changed, rebuild the full projection. Tail-only shrink and style-only prefix changes continue to preserve native scrollback; pending resize replay retains its temporary tail view.
+- Evidence: `test/unit/tui-engine-local-deltas.test.ts` covers stale transient rows, all Composer rows after a selector closes, and simultaneous shrink plus style-only changes without duplicate answer rows.
+- Removal condition: the selected Pi baseline supplies equivalent structural-collapse handling.

packages/tui/src/tui/engine/tui-main-screen.ts

@@ -2,7 +2,7 @@ import * as fs from "node:fs";
 import * as path from "node:path";
 import { deleteKittyImage, isImageLine } from "./terminal-image.js";
 import { type TUI, TuiBase, type TuiStopOptions } from "./tui.js";
-import { visibleWidth } from "./utils.js";
+import { stripTerminalSequences, visibleWidth } from "./utils.js";
 
 const KITTY_SEQUENCE_PREFIX = "\x1b_G";
 const MAX_RENDER_WRITE_CHARS = 1024 * 1024;
@@ -308,9 +308,13 @@ export class TuiMainScreen extends TuiBase implements TUI {
 			// previous viewport origin so rows already scrolled out are not painted twice,
 			// and growth still writes every row before it scrolls out. Resize previews are
 			// temporary: they show the new tail until the pending full history replay.
-			if (viewportOnly && !this.historyReplayPending && newLines.length <= prevViewportTop) {
-				// Nothing remains addressable on screen; rebuild with one consistent origin.
-				viewportOnly = false;
+			if (viewportOnly && !this.historyReplayPending) {
+				// A shrink can move new content (including the Composer) into immutable
+				// scrollback. Rebuild when that prefix changes, but ignore style-only edits.
+				const changedScrolledPrefix = newLines.length < this.previousLines.length &&
+					newLines.slice(0, prevViewportTop).some((line, index) =>
+						stripTerminalSequences(line) !== stripTerminalSequences(this.previousLines[index] ?? ""));
+				if (newLines.length <= prevViewportTop || changedScrolledPrefix) viewportOnly = false;
 			}
 			const start = viewportOnly
 				? this.historyReplayPending

packages/tui/test/unit/tui-engine-local-deltas.test.ts

@@ -56,7 +56,7 @@ describe('MCode Pi Engine local deltas', () => {
     }
   });
 
-  it('preserves native scrollback when transient rows shrink above the viewport', async () => {
+  it('rebuilds when a transient collapse changes rows already in scrollback', async () => {
     const terminal = new RecordingVirtualTerminal(40, 5);
     const tui = new TuiMainScreen(terminal);
     const component = new MutableLines();
@@ -81,13 +81,55 @@ describe('MCode Pi Engine local deltas', () => {
 
     const writes = terminal.takeWrites();
     expect(writes).toContain('\x1b[2J\x1b[H');
-    expect(writes).not.toContain('\x1b[3J');
-    expect(terminal.getScrollBuffer()).toContain('activity-1');
-    expect(terminal.getViewport()).toEqual(['composer', '', '', '', '']);
+    expect(writes).toContain('\x1b[3J');
+    expect(terminal.getScrollBuffer()).not.toContain('activity-1');
+    expect(terminal.getViewport()).toEqual(['header', 'status', 'composer', '', '']);
     expect(terminal.getScrollBuffer().filter((line) => line === 'header')).toHaveLength(1);
     expect(tui.fullRedraws).toBe(2);
   });
 
+  it('keeps every composer row visible after a collapse crosses the viewport origin', async () => {
+    const terminal = new RecordingVirtualTerminal(40, 10);
+    const tui = new TuiMainScreen(terminal);
+    const component = new MutableLines();
+    const chat = Array.from({ length: 15 }, (_, index) => `Chat ${index}`);
+    const composer = ['Editor 0', 'Editor 1', `Editor 2${CURSOR_MARKER}`];
+    component.lines = [...chat, ...composer];
+    tui.addChild(component);
+    tui.renderNow();
+    await terminal.flush();
+
+    component.lines = [
+      ...chat,
+      ...Array.from({ length: 8 }, (_, index) => `Selector ${index}`),
+    ];
+    tui.renderNow();
+    await terminal.flush();
+    component.lines = [...chat, ...composer];
+    tui.renderNow();
+    await terminal.flush();
+    terminal.takeWrites();
+
+    component.lines = [...chat.slice(0, 12), ...composer];
+    tui.renderNow();
+    await terminal.flush();
+
+    expect(terminal.takeWrites()).toContain('\x1b[3J');
+    expect(terminal.getViewport()).toEqual([
+      ...chat.slice(5, 12),
+      'Editor 0',
+      'Editor 1',
+      'Editor 2',
+    ]);
+    expect(terminal.getScrollBuffer()).toEqual([
+      ...chat.slice(0, 12),
+      'Editor 0',
+      'Editor 1',
+      'Editor 2',
+    ]);
+    expect(terminal.getCursorPosition()).toEqual({ x: 8, y: 9 });
+  });
+
   it('does not replay scrolled answer rows after a narrow terminal frame shrinks', async () => {
     const terminal = new RecordingVirtualTerminal(67, 44);
     const tui = new TuiMainScreen(terminal);
@@ -99,11 +141,13 @@ describe('MCode Pi Engine local deltas', () => {
     await terminal.flush();
 
     // Settle the activity row, then repaint a historical line (for example Markdown styling).
+    terminal.takeWrites();
     component.lines = [...answer, `composer${CURSOR_MARKER}`, 'status'];
+    component.lines[0] = '\x1b[1mAnswer line 0\x1b[0m';
     tui.renderNow();
     await terminal.flush();
-    terminal.takeWrites();
-    component.lines[0] = '\x1b[1mAnswer line 0\x1b[0m';
+    expect(terminal.takeWrites()).not.toContain('\x1b[3J');
+    component.lines[0] = '\x1b[3mAnswer line 0\x1b[0m';
     tui.renderNow();
     await terminal.flush();