Revert "fix: 终端内容溢出 viewport 时的重影 bug"

This reverts commit 3d18e1da58.

packages/@ant/ink/src/core/ink.tsx

@@ -74,7 +74,6 @@ import {
   DISABLE_MODIFY_OTHER_KEYS,
   ENABLE_KITTY_KEYBOARD,
   ENABLE_MODIFY_OTHER_KEYS,
-  ERASE_DOWN,
   ERASE_SCREEN,
 } from './termio/csi.js';
 import {
@@ -107,17 +106,6 @@ const ERASE_THEN_HOME_PATCH = Object.freeze({
   type: 'stdout' as const,
   content: ERASE_SCREEN + CURSOR_HOME,
 });
-// Main-screen self-healing: CURSOR_HOME then ERASE_DOWN (CSI J) clears the
-// entire visible viewport from (0,0) without touching scrollback. ERASE_SCREEN
-// (CSI 2 J) on xterm.js / VSCode integrated terminals can produce residual
-// ghosting because its implementation interacts with the scrollback boundary;
-// CSI J has deterministic "erase from cursor to end of screen" semantics that
-// never push visible content into scrollback. Order matters: home first, then
-// erase — so the erase covers the full viewport.
-const HOME_THEN_ERASE_DOWN_PATCH = Object.freeze({
-  type: 'stdout' as const,
-  content: CURSOR_HOME + ERASE_DOWN,
-});
 
 // Cached per-Ink-instance, invalidated on resize. frame.cursor.y for
 // alt-screen is always terminalRows - 1 (renderer.ts).
@@ -795,15 +783,10 @@ export default class Ink {
     } else if (this.needsEraseBeforePaint && hasDiff) {
       // Main-screen periodic self-healing: clear visible terminal before
       // painting the diff. Without this, rows past the new frame's height
-      // would retain stale content from the previous frame. Uses
-      // HOME_THEN_ERASE_DOWN_PATCH (CSI H + CSI J) instead of ERASE_SCREEN
-      // (CSI 2 J): the latter's behavior on xterm.js / VSCode integrated
-      // terminals can leave residual ghosting of the prior frame (banner +
-      // status bar duplicated). CSI J erases from cursor (now at 0,0) to
-      // end of screen with deterministic semantics and does not touch
-      // scrollback, so the user's conversation history is preserved.
+      // would retain stale content from the previous frame. BSU/ESU keeps
+      // old content visible until the full erase+paint is flushed atomically.
       this.needsEraseBeforePaint = false;
-      optimized.unshift(HOME_THEN_ERASE_DOWN_PATCH);
+      optimized.unshift(ERASE_THEN_HOME_PATCH);
     }
 
     // Native cursor positioning: park the terminal cursor at the declared

packages/@ant/ink/src/core/log-update.ts

@@ -225,23 +225,27 @@ export class LogUpdate {
       cursorAtBottom &&
       !isGrowing
     ) {
-      // Frame persistently overflows the viewport. The cursor-restore LF at the
-      // end of the previous frame scrolled content into scrollback, and the
-      // terminal's auto-scroll on cursor movement causes our relative-cursor
-      // tracking to drift — visible-region diffs then land on the wrong rows
-      // and produce ghosting (duplicate banners, shifted content).
-      //
-      // Relative cursor ops can't repaint scrollback rows at all, and even
-      // visible-region writes are unsafe because the cursor origin we computed
-      // doesn't match where the terminal thinks it is. Full-reset emits
-      // clearTerminal (CSI 2 J + CSI 3 J + CSI H), wiping scrollback residue
-      // and cursor drift, then repaints the whole frame from (0,0).
-      //
-      // Previously this branch only fired when a diff existed in the scrollback
-      // region; visible-region-only changes still produced ghosting. Cost: an
-      // extra clear+repaint per render while content overflows. Acceptable
-      // because overflow is the exception, not the steady state of a TUI.
-      return fullResetSequence_CAUSES_FLICKER(next, 'offscreen', stylePool)
+      // viewportY = rows in scrollback from content overflow
+      // +1 for the row pushed by cursor-restore scroll
+      const viewportY = prev.screen.height - prev.viewport.height
+      const scrollbackRows = viewportY + 1
+
+      let scrollbackChangeY = -1
+      diffEach(prev.screen, next.screen, (_x, y) => {
+        if (y < scrollbackRows) {
+          scrollbackChangeY = y
+          return true // early exit
+        }
+      })
+      if (scrollbackChangeY >= 0) {
+        const prevLine = readLine(prev.screen, scrollbackChangeY)
+        const nextLine = readLine(next.screen, scrollbackChangeY)
+        return fullResetSequence_CAUSES_FLICKER(next, 'offscreen', stylePool, {
+          triggerY: scrollbackChangeY,
+          prevLine,
+          nextLine,
+        })
+      }
     }
 
     const screen = new VirtualScreen(prev.cursor, next.viewport.width)

packages/@ant/ink/src/core/termio/csi.ts

@@ -227,12 +227,6 @@ export const ERASE_SCREEN = csi(2, 'J')
 /** Erase scrollback buffer (CSI 3 J) */
 export const ERASE_SCROLLBACK = csi(3, 'J')
 
-/** Erase from cursor to end of screen (CSI J) — constant form.
- *  Unlike ERASE_SCREEN (CSI 2 J), this never pushes content into scrollback
- *  on xterm.js / VSCode integrated terminals, making it safe for periodic
- *  self-healing redraws in main-screen mode. */
-export const ERASE_DOWN = csi('J')
-
 /**
  * Erase n lines starting from cursor line, moving cursor up
  * This erases each line and moves up, ending at column 1