fix(buffer): avoid shared _extendedAttrs sentinel breaking addon-image

EMPTY_SPARSE_EXTENDED was shared across lines via copyFrom; addon-image
writes _extendedAttrs directly without copy-on-write, which caused tile
eviction failures and broke instanceof Object checks.

Use undefined for empty extended maps (keep EMPTY_SPARSE_MAP for _combined).
Ensure addon-image forks the map before writes and update the accessor test.

Co-authored-by: Daniel Imms <Tyriar@users.noreply.github.com>

.github/workflows/ci.yml

@@ -6,19 +6,14 @@ on:
   pull_request:
     branches: [ "master" ]
 
-permissions:
-  contents: read 
-
 jobs:
   build:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-    - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-      with:
-        persist-credentials: false
+    - uses: actions/checkout@v5
     - name: Use Node.js 22.x
-      uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
+      uses: actions/setup-node@v5
       with:
         node-version: 22.x
         cache: 'npm'
@@ -74,7 +69,7 @@ jobs:
           ./addons/addon-webgl/out/* \
           ./addons/addon-webgl/out-*st/*
     - name: Upload artifacts
-      uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6
+      uses: actions/upload-artifact@v6
       with:
         name: build-artifacts
         path: compressed-build.zip
@@ -84,11 +79,9 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-    - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-      with:
-        persist-credentials: false
+    - uses: actions/checkout@v5
     - name: Use Node.js 22.x
-      uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
+      uses: actions/setup-node@v5
       with:
         node-version: 22.x
         cache: 'npm'
@@ -107,18 +100,16 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-    - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-      with:
-        persist-credentials: false
+    - uses: actions/checkout@v5
     - name: Use Node.js 22.x
-      uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
+      uses: actions/setup-node@v5
       with:
         node-version: 22.x
         cache: 'npm'
     - name: Install dependencies
       run: |
         npm ci
-    - uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7
+    - uses: actions/download-artifact@v7
       with:
         name: build-artifacts
     - name: Unzip artifacts
@@ -146,18 +137,16 @@ jobs:
         runs-on: [ubuntu, macos, windows]
     runs-on: ${{ matrix.runs-on }}-latest
     steps:
-    - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-      with:
-        persist-credentials: false
+    - uses: actions/checkout@v5
     - name: Use Node.js ${{ matrix.node-version }}.x
-      uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
+      uses: actions/setup-node@v5
       with:
         node-version: ${{ matrix.node-version }}.x
         cache: 'npm'
     - name: Install dependencies
       run: |
         npm ci
-    - uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7
+    - uses: actions/download-artifact@v7
       with:
         name: build-artifacts
     - name: Unzip artifacts
@@ -182,11 +171,9 @@ jobs:
         browser: [chromium, firefox, webkit]
     runs-on: ${{ matrix.runs-on }}
     steps:
-    - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-      with:
-        persist-credentials: false
+    - uses: actions/checkout@v5
     - name: Use Node.js ${{ matrix.node-version }}.x
-      uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
+      uses: actions/setup-node@v5
       with:
         node-version: ${{ matrix.node-version }}.x
         cache: 'npm'
@@ -195,7 +182,7 @@ jobs:
         npm ci
     - name: Install playwright
       run: npx playwright install --with-deps ${{ matrix.browser }}
-    - uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7
+    - uses: actions/download-artifact@v7
       with:
         name: build-artifacts
     - name: Unzip artifacts
@@ -245,11 +232,9 @@ jobs:
       matrix:
         node-version: [22]
     steps:
-    - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-      with:
-        persist-credentials: false
+    - uses: actions/checkout@v5
     - name: Use Node.js ${{ matrix.node-version }}.x
-      uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
+      uses: actions/setup-node@v5
       with:
         node-version: ${{ matrix.node-version }}.x
         cache: 'npm'
@@ -258,7 +243,7 @@ jobs:
         npm ci
     - name: Install playwright
       run: npx playwright install
-    - uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7
+    - uses: actions/download-artifact@v7
       with:
         name: build-artifacts
     - name: Unzip artifacts

.github/workflows/codeql-analysis.yml

@@ -8,11 +8,6 @@ on:
   schedule:
     - cron: '41 17 * * 0'
 
-permissions:
-  actions: read          
-  contents: read          
-  security-events: write 
-
 jobs:
   analyze:
     name: Analyze
@@ -29,14 +24,12 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-      with:
-        persist-credentials: false
+      uses: actions/checkout@v5
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@8aad20d150bbac5944a9f9d289da16a4b0d87c1e # v4
+      uses: github/codeql-action/init@v4
       with:
         languages: ${{ matrix.language }}
     - name: Autobuild
-      uses: github/codeql-action/autobuild@8aad20d150bbac5944a9f9d289da16a4b0d87c1e # v4
+      uses: github/codeql-action/autobuild@v4
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@8aad20d150bbac5944a9f9d289da16a4b0d87c1e # v4
+      uses: github/codeql-action/analyze@v4

.github/workflows/copilot-setup-steps.yml

@@ -9,9 +9,6 @@ on:
     paths:
       - .github/workflows/copilot-setup-steps.yml
 
-permissions:
-  contents: read
-
 jobs:
   copilot-setup-steps:
     runs-on: ubuntu-latest
@@ -21,11 +18,9 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-        with:
-          persist-credentials: false
+        uses: actions/checkout@v5
       - name: Use Node.js 22.x
-        uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
+        uses: actions/setup-node@v5
         with:
           node-version: 22.x
           cache: 'npm'

.github/workflows/release.yml

@@ -6,18 +6,13 @@ on:
     # without running tests to save time to publish
     branches: [ "master" ]
 
-permissions:
-  contents: read
-
 jobs:
   release:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-      with:
-        persist-credentials: false
+    - uses: actions/checkout@v5
     - name: Use Node.js 22.x
-      uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
+      uses: actions/setup-node@v5
       with:
         node-version: 22.x
         cache: 'npm'

README.md

@@ -254,13 +254,6 @@ Xterm.js is used in many world-class applications to provide great terminal expe
 - [**WooTTY**](https://github.com/icoretech/wootty): Flawless browser terminal for real operators.
 - [**Orca**](https://github.com/stablyai/orca): Agentic development environment for 100x builders.
 - [**4bit**](https://ciembor.github.io/4bit): Terminal Color Scheme Designer.
-- [**Cate**](https://github.com/0-AI-UG/cate): Open source desktop IDE on an infinite zoomable canvas. Editor, browser, and terminal panels float in spatial space; the terminals are xterm.js with the WebGL addon, backed by node-pty.
-- [**OmnyShell PWA**](https://github.com/OmnyGrid/omnyshell_web): Web client for [**OmnyShell**](https://github.com/OmnyGrid/omnyshell), featuring remote terminals, a built-in IDE, AI-assisted workflows, and detachable/resumable sessions for seamless browser-based access to nodes.
-- [**kmux**](https://github.com/kkd927/kmux): A keyboard-centric terminal workspace for running parallel AI coding agents side by side on macOS and Linux.
-- [**LynxHub**](https://github.com/KindaBrazy/LynxHub): Cross-platform, extensible terminal and browser for AI management.
-- [**Codeman**](https://github.com/Ark0N/Codeman): Self-hosted mission control for AI coding agents, streaming live tmux sessions to browser and phone.
-- [**JSVIsion**](https://github.com/blendsdk/jsvision): A Turbo Vision-Style TUI SDK for TypeScript. We use xterm.js in our docs to show live JSVision examples running in a web terminal.
-- [**BitFun**](https://github.com/GCWing/BitFun): Open-source desktop AI agent whose integrated terminals and read-only terminal output views use xterm.js with the Fit, Web Links, and WebGL addons.
 - [And much more...](https://github.com/xtermjs/xterm.js/network/dependents?package_id=UGFja2FnZS0xNjYzMjc4OQ%3D%3D)
 
 Do you use xterm.js in your application as well? Please [open a Pull Request](https://github.com/sourcelair/xterm.js/pulls) to include it here. We would love to have it on our list. Please add any new contributions to the end of the list.

addons/addon-image/README.md

@@ -98,7 +98,7 @@ terminal.loadAddon(imageAddon);
   Set by default, change it with `{iipSupport: true}`.
 
   The IIP implementation has the following features / restrictions (sequence will silently fail for unmet conditions):
-  - Supported formats: PNG, JPEG, GIF, QOI, WEBP and AVIF
+  - Supported formats: PNG, JPEG, GIF and QOI
   - No animation support.
   - Image type hinting is not supported (always deducted from data header).
   - File download is not supported.
@@ -112,13 +112,6 @@ terminal.loadAddon(imageAddon);
   - ReportCellSize sequence is supported.
   - Hi-res display support is currently limited (image gets blurred).
 
-- **Note on IIP image format support**  
-  For all image formats except QOI the addon only does the dimension extraction and leaves
-  the image decoding to the underlying browser engine. Note that some formats are implemented
-  and enabled with different constraints by browser vendors, especially newer formats
-  (e.g. under Firefox you might need to change the setting _image.avif.compliance_strictness_ to 0
-  to get broader AVIF support).
-
 - **Kitty Graphics Support (TGP)**  
   Set by default, change it with `{kittySupport: true}`.
 

addons/addon-image/src/IIPHandler.ts

@@ -39,6 +39,7 @@ export class IIPHandler implements IOscHandler, IResetHandler {
   private _header: IHeaderFields = DEFAULT_HEADER;
   private _dec: Base64Decoder;
   private _qoiDec: QoiDecoder;
+  private _metrics = UNSUPPORTED_TYPE;
   private _isMultipart = false;
   private _abortMulti = false;
 
@@ -62,6 +63,7 @@ export class IIPHandler implements IOscHandler, IResetHandler {
 
   public start(): void {
     this._aborted = false;
+    this._metrics  = UNSUPPORTED_TYPE;
     this._hp.reset();
   }
 
@@ -118,14 +120,14 @@ export class IIPHandler implements IOscHandler, IResetHandler {
 
     if (seqType === SequenceType.REPORTCELLSIZE) {
       // OSC 1337 ; ReportCellSize=[height];[width];[scale] ST
-      let w = CELL_SIZE_DEFAULT.width;
-      let h = CELL_SIZE_DEFAULT.height;
+      let width = CELL_SIZE_DEFAULT.width;
+      let height = CELL_SIZE_DEFAULT.height;
       if (this._renderer.dimensions) {
-        w = this._renderer.dimensions.css.canvas.width / this._coreTerminal.cols;
-        h = this._renderer.dimensions.css.canvas.height / this._coreTerminal.rows;
+        width = this._renderer.dimensions.css.canvas.width / this._coreTerminal.cols;
+        height = this._renderer.dimensions.css.canvas.height / this._coreTerminal.rows;
       }
       const scale = this._coreTerminal._core._coreBrowserService?.dpr ?? 1;
-      const report = `\x1b]1337;ReportCellSize=${h.toFixed(3)};${w.toFixed(3)};${scale.toFixed(3)}\x1b\\`;
+      const report = `\x1b]1337;ReportCellSize=${height.toFixed(3)};${width.toFixed(3)};${scale.toFixed(3)}\x1b\\`;
       this._coreTerminal.input(report, false);
       return true;
     }
@@ -152,24 +154,17 @@ export class IIPHandler implements IOscHandler, IResetHandler {
 
     // early exit condition chain
     let cond: number | boolean;
-    let metrics = UNSUPPORTED_TYPE;
     if (cond = success) {
       if (cond = !this._dec.end()) {
-        metrics = imageType(this._dec.data8);
-        if (cond = metrics.mime !== 'unsupported') {
-          w = metrics.width;
-          h = metrics.height;
+        this._metrics = imageType(this._dec.data8);
+        if (cond = this._metrics.mime !== 'unsupported') {
+          w = this._metrics.width;
+          h = this._metrics.height;
           if (cond = w && h && w * h < this._opts.pixelLimit) {
             [w, h] = this._resize(w, h).map(Math.floor);
             cond = w && h && w * h < this._opts.pixelLimit;
-          } else {
-            console.warn(`IIP: image dimension issue ${metrics.width}x${metrics.height}`);
           }
-        } else {
-          console.warn('IIP: unsupported image type');
         }
-      } else {
-        console.warn('IIP: error during BASE64 decoding');
       }
     }
     if (!cond) {
@@ -178,7 +173,7 @@ export class IIPHandler implements IOscHandler, IResetHandler {
     }
 
     let blob: Blob | ImageData;
-    if (metrics.mime === 'image/qoi') {
+    if (this._metrics.mime === 'image/qoi') {
       const data = this._qoiDec.decode(this._dec.data8);
       blob = new ImageData(
         new Uint8ClampedArray(data.buffer, data.byteOffset, data.byteLength),
@@ -195,17 +190,13 @@ export class IIPHandler implements IOscHandler, IResetHandler {
         return true;
       }
     } else {
-      blob = new Blob([this._dec.data8], { type: metrics.mime });
+      blob = new Blob([this._dec.data8], { type: this._metrics.mime });
     }
     this._dec.release();
     return createImageBitmap(blob, { resizeWidth: w, resizeHeight: h })
       .then(bm => {
         this._storage.addImage(bm);
         return true;
-      })
-      .catch(e => {
-        console.warn(`IIP: decoding error ${metrics.mime} ${metrics.width}x${metrics.height}`, e);
-        return true;
       });
   }
 

addons/addon-image/src/IIPMetrics.test.ts

@@ -32,28 +32,6 @@ const TEST_IMAGES: [string, IMetrics][] = [
   ['agfa-makernotes.jpg', { mime: 'image/jpeg', width: 8, height: 8 }],
   ['sony-alpha-6000.jpg', { mime: 'image/jpeg', width: 6000, height: 4000 }],
   ['dice.qoi', { mime: 'image/qoi', width: 800, height: 600 }],
-  // VP8
-  ['1.webp', { mime: 'image/webp', width: 550, height: 368 }],
-  ['2.webp', { mime: 'image/webp', width: 550, height: 404 }],
-  ['3.webp', { mime: 'image/webp', width: 1280, height: 720 }],
-  ['4.webp', { mime: 'image/webp', width: 1024, height: 772 }],
-  ['5.webp', { mime: 'image/webp', width: 1024, height: 752 }],
-  // VP8X
-  ['1_webp_a.webp', { mime: 'image/webp', width: 400, height: 301 }],
-  ['2_webp_a.webp', { mime: 'image/webp', width: 386, height: 395 }],
-  ['3_webp_a.webp', { mime: 'image/webp', width: 800, height: 600 }],
-  ['4_webp_a.webp', { mime: 'image/webp', width: 421, height: 163 }],
-  ['5_webp_a.webp', { mime: 'image/webp', width: 300, height: 300 }],
-  // VP8L
-  ['1_webp_ll.webp', { mime: 'image/webp', width: 400, height: 301 }],
-  ['2_webp_ll.webp', { mime: 'image/webp', width: 386, height: 395 }],
-  ['3_webp_ll.webp', { mime: 'image/webp', width: 800, height: 600 }],
-  ['4_webp_ll.webp', { mime: 'image/webp', width: 421, height: 163 }],
-  ['5_webp_ll.webp', { mime: 'image/webp', width: 300, height: 300 }],
-  // some AVIF test images
-  ['fox.profile2.12bpc.yuv444.odd-width.odd-height.avif', { mime: 'image/avif', width: 1203, height: 799 }],
-  ['hato.profile0.8bpc.yuv420.avif', { mime: 'image/avif', width: 3082, height: 2048 }],
-  ['kimono.crop.avif', { mime: 'image/avif', width: 722, height: 1024 }],
 ];
 
 

addons/addon-image/src/IIPMetrics.ts

@@ -4,7 +4,7 @@
  */
 
 
-export type ImageType = 'image/png' | 'image/jpeg' | 'image/gif' | 'image/qoi' | 'image/webp' | 'image/avif' | 'unsupported' | '';
+export type ImageType = 'image/png' | 'image/jpeg' | 'image/gif' | 'image/qoi' | 'unsupported' | '';
 
 export interface IMetrics {
   mime: ImageType;
@@ -19,16 +19,16 @@ export const UNSUPPORTED_TYPE: IMetrics = {
 };
 
 export function imageType(d: Uint8Array): IMetrics {
-  if (d.length < 32) {
+  if (d.length < 24) {
     return UNSUPPORTED_TYPE;
   }
-  const d32 = new Uint32Array(d.buffer, d.byteOffset, 8);
+  const d32 = new Uint32Array(d.buffer, d.byteOffset, 6);
   // PNG: 89 50 4E 47 0D 0A 1A 0A (8 first bytes == magic number for PNG)
   // + first chunk must be IHDR
   if (d32[0] === 0x474E5089 && d32[1] === 0x0A1A0A0D && d32[3] === 0x52444849) {
     return {
       mime: 'image/png',
-      width:  d[16] << 24 | d[17] << 16 | d[18] << 8 | d[19],
+      width: d[16] << 24 | d[17] << 16 | d[18] << 8 | d[19],
       height: d[20] << 24 | d[21] << 16 | d[22] << 8 | d[23]
     };
   }
@@ -41,7 +41,7 @@ export function imageType(d: Uint8Array): IMetrics {
   if (d32[0] === 0x38464947 && (d[4] === 0x37 || d[4] === 0x39) && d[5] === 0x61) {
     return {
       mime: 'image/gif',
-      width:  d[7] << 8 | d[6],
+      width: d[7] << 8 | d[6],
       height: d[9] << 8 | d[8]
     };
   }
@@ -49,71 +49,13 @@ export function imageType(d: Uint8Array): IMetrics {
   if (d32[0] === 0x66696F71) {
     return {
       mime: 'image/qoi',
-      width:  d[4] << 24 | d[5] << 16 | d[6] << 8 | d[7],
+      width: d[4] << 24 | d[5] << 16 | d[6] << 8 | d[7],
       height: d[8] << 24 | d[9] << 16 | d[10] << 8 | d[11]
     };
   }
-  // WEBP: RIFF | xxxx | WEBP | VP8x
-  if (d32[0] === 0x46464952 && d32[2] === 0x50424557 && (d32[3] & 0xFFFFFF) === 0x385056) {
-    switch (d[15]) {
-      case 0x58:  // Extended WebP VP8X --> "X"
-        return {
-          mime: 'image/webp',
-          width:  (d[24] | d[25] << 8 | d[26] << 16) + 1,
-          height: (d[27] | d[28] << 8 | d[29] << 16) + 1
-        };
-      case 0x4C:  // Lossless WebP VP8L --> "L"
-        if (d[20] !== 0x2f) return UNSUPPORTED_TYPE;
-        const dim = d[21] | d[22] << 8 | d[23] << 16 | d[24] << 24;
-        return {
-          mime: 'image/webp',
-          width:  (dim        & 0x3FFF) + 1,
-          height: (dim >>> 14 & 0x3FFF) + 1
-        };
-      case 0x20:  // Lossy WebP VP8  --> " "
-        if (d[23] !== 0x9d || d[24] !== 0x01 || d[25] !== 0x2a) return UNSUPPORTED_TYPE;
-        return {
-          mime: 'image/webp',
-          width:  (d[26] | d[27] << 8) & 0x3FFF,
-          height: (d[28] | d[29] << 8) & 0x3FFF
-        };
-    }
-    return UNSUPPORTED_TYPE;
-  }
-  // AVIF: Box size | ftyp | avif/avis
-  if (d32[1] === 0x70797466 && (d32[2] === 0x66697661 || d32[2] === 0x73697661)) {
-    let pos = -1;
-    // search for ispe box within first 1024 bytes
-    const limit = Math.min(d.length - 16, 1024);
-    for (let i = 8; i < limit; i++) {
-      // scan for ispe
-      if (d[i] === 0x69 && d[i + 1] === 0x73 && d[i + 2] === 0x70 && d[i + 3] === 0x65) {
-        pos = i;
-        break;
-      }
-    }
-    if (pos !== -1) {
-      // dimensions are in BE at +8 (width) at +12 (height)
-      const width =
-        d[pos +  8] << 24 |
-        d[pos +  9] << 16 |
-        d[pos + 10] <<  8 |
-        d[pos + 11];
-      const height =
-        d[pos + 12] << 24 |
-        d[pos + 13] << 16 |
-        d[pos + 14] <<  8 |
-        d[pos + 15];
-      if (width > 0 && height > 0) {
-        return { mime: 'image/avif', width, height };
-      }
-    }
-    return UNSUPPORTED_TYPE;
-  }
   return UNSUPPORTED_TYPE;
 }
 
-
 function jpgSize(d: Uint8Array): [number, number] {
   const len = d.length;
   let i = 4;

addons/addon-image/src/ImageStorage.ts

@@ -5,11 +5,12 @@
 
 import { IDisposable } from '@xterm/xterm';
 import { ImageRenderer } from './ImageRenderer';
-import type {
-  ITerminalExt, IImageAddonOptions, IImageSpec, ICellSize, IAddImageOpts
+import {
+  ITerminalExt, IExtendedAttrsImage, IImageAddonOptions, IImageSpec,
+  IBufferLineExt, BgFlags, Cell, Content, ICellSize, ExtFlags, Attributes,
+  UnderlineStyle, IAddImageOpts
 } from './Types';
-import type { IBufferLine } from 'common/buffer/Types';
-import { CellData } from 'common/buffer/CellData';
+
 
 // fallback default cell size
 export const CELL_SIZE_DEFAULT: ICellSize = {
@@ -17,12 +18,93 @@ export const CELL_SIZE_DEFAULT: ICellSize = {
   height: 14
 };
 
-class ImageTileInfo {
+/**
+ * Extend extended attribute to also hold image tile information.
+ *
+ * Object definition is copied from base repo to fully mimick its behavior.
+ * Image data is added as additional public properties `imageId` and `tileId`.
+ */
+class ExtendedAttrsImage implements IExtendedAttrsImage {
+  private _ext: number = 0;
+  public get ext(): number {
+    if (this._urlId) {
+      return (
+        (this._ext & ~ExtFlags.UNDERLINE_STYLE) |
+        (this.underlineStyle << 26)
+      );
+    }
+    return this._ext;
+  }
+  public set ext(value: number) { this._ext = value; }
+
+  public get underlineStyle(): UnderlineStyle {
+    // Always return the URL style if it has one
+    if (this._urlId) {
+      return UnderlineStyle.DASHED;
+    }
+    return (this._ext & ExtFlags.UNDERLINE_STYLE) >> 26;
+  }
+  public set underlineStyle(value: UnderlineStyle) {
+    this._ext &= ~ExtFlags.UNDERLINE_STYLE;
+    this._ext |= (value << 26) & ExtFlags.UNDERLINE_STYLE;
+  }
+
+  public get underlineColor(): number {
+    return this._ext & (Attributes.CM_MASK | Attributes.RGB_MASK);
+  }
+  public set underlineColor(value: number) {
+    this._ext &= ~(Attributes.CM_MASK | Attributes.RGB_MASK);
+    this._ext |= value & (Attributes.CM_MASK | Attributes.RGB_MASK);
+  }
+
+  public get underlineVariantOffset(): number {
+    const val = (this._ext & ExtFlags.VARIANT_OFFSET) >> 29;
+    if (val < 0) {
+      return val ^ 0xFFFFFFF8;
+    }
+    return val;
+  }
+  public set underlineVariantOffset(value: number) {
+    this._ext &= ~ExtFlags.VARIANT_OFFSET;
+    this._ext |= (value << 29) & ExtFlags.VARIANT_OFFSET;
+  }
+
+  private _urlId: number = 0;
+  public get urlId(): number {
+    return this._urlId;
+  }
+  public set urlId(value: number) {
+    this._urlId = value;
+  }
+
   constructor(
+    ext: number = 0,
+    urlId: number = 0,
     public imageId = -1,
-    public tileId = -1) {
+    public tileId = -1
+  ) {
+    this._ext = ext;
+    this._urlId = urlId;
+  }
+
+  public clone(): IExtendedAttrsImage {
+    /**
+     * Technically we dont need a clone variant of ExtendedAttrsImage,
+     * as we never clone a cell holding image data.
+     * Note: Clone is only meant to be used by the InputHandler for
+     * sticky attributes, which is never the case for image data.
+     * We still provide a proper clone method to reflect the full ext attr
+     * state in case there are future use cases for clone.
+     */
+    return new ExtendedAttrsImage(this._ext, this._urlId, this.imageId, this.tileId);
+  }
+
+  public isEmpty(): boolean {
+    return this.underlineStyle === UnderlineStyle.NONE && this._urlId === 0 && this.imageId === -1;
   }
 }
+const EMPTY_ATTRS = new ExtendedAttrsImage();
+
 
 /**
  * ImageStorage - extension of CoreTerminal:
@@ -44,7 +126,6 @@ export class ImageStorage implements IDisposable {
   private _needsFullClear = false;
   // hard limit of stored pixels (fallback limit of 10 MB)
   private _pixelLimit: number = 2500000;
-  private _workCell: CellData = new CellData();
 
   private _viewportMetrics: { cols: number, rows: number };
   public onImageAdded: (() => void) | undefined;
@@ -196,10 +277,10 @@ export class ImageStorage implements IDisposable {
 
     this._terminal._core._inputHandler._dirtyRowTracker.markDirty(buffer.y);
     for (let row = 0; row < rows; ++row) {
-      const line = buffer.lines.get(buffer.y + buffer.ybase)!;
+      const line = buffer.lines.get(buffer.y + buffer.ybase);
       for (let col = 0; col < cols; ++col) {
         if (offset + col >= termCols) break;
-        this._writeToCell(line, offset + col, imageId, row * cols + col);
+        this._writeToCell(line as IBufferLineExt, offset + col, imageId, row * cols + col);
         tileCount++;
       }
       if (opts.scrolling) {
@@ -346,44 +427,55 @@ export class ImageStorage implements IDisposable {
     const placeholderCalls: { col: number, row: number, count: number }[] = [];
 
     // walk all cells in viewport and collect tiles found
+    // Note: We check _extendedAttrs directly (not just HAS_EXTENDED flag)
+    // because text writes clear the BG flag but leave image tile data intact.
+    // This lets top-layer images survive text overwrites (kitty C=1 behavior).
     for (let row = start; row <= end; ++row) {
-      const line = buffer.lines.get(row + buffer.ydisp);
+      const line = buffer.lines.get(row + buffer.ydisp) as IBufferLineExt;
       if (!line) return;
       for (let col = 0; col < cols; ++col) {
-        const e = line.getExtended(col)?.payload;
-        if (e instanceof ImageTileInfo) {
-          const imageId = e.imageId;
-          if (imageId === undefined || imageId === -1) {
+        let e: IExtendedAttrsImage;
+        if (line.getBg(col) & BgFlags.HAS_EXTENDED) {
+          e = line._extendedAttrs?.[col] ?? EMPTY_ATTRS;
+        } else {
+          const maybeImg = line._extendedAttrs?.[col] as IExtendedAttrsImage | undefined;
+          if (!maybeImg || maybeImg.imageId === undefined || maybeImg.imageId === -1) {
             continue;
           }
-          const imgSpec = this._images.get(imageId);
-          if (e.tileId !== -1) {
-            const startTile = e.tileId;
-            const startCol = col;
-            let count = 1;
-            /**
-             * merge tiles to the right into a single draw call, if:
-             * - not at end of line
-             * - cell has same image id
-             * - cell has consecutive tile id
-             */
-            while (++col < cols) {
-              const nextE = line.getExtended(col)?.payload;
-              if (!(nextE instanceof ImageTileInfo) || nextE.imageId !== imageId || nextE.tileId !== startTile + count) {
-                break;
-              }
-              count++;
+          e = maybeImg;
+        }
+        const imageId = e.imageId;
+        if (imageId === undefined || imageId === -1) {
+          continue;
+        }
+        const imgSpec = this._images.get(imageId);
+        if (e.tileId !== -1) {
+          const startTile = e.tileId;
+          const startCol = col;
+          let count = 1;
+          /**
+           * merge tiles to the right into a single draw call, if:
+           * - not at end of line
+           * - cell has same image id
+           * - cell has consecutive tile id
+           * Also check _extendedAttrs directly for cells where text cleared HAS_EXTENDED.
+           */
+          while (++col < cols) {
+            const nextE = line._extendedAttrs?.[col] as IExtendedAttrsImage | undefined;
+            if (!nextE || nextE.imageId !== imageId || nextE.tileId !== startTile + count) {
+              break;
             }
-            col--;
-            if (imgSpec) {
-              if (imgSpec.actual) {
-                drawCalls.push({ imgSpec, tileId: startTile, col: startCol, row, count });
-              }
-            } else if (this._opts.showPlaceholder) {
-              placeholderCalls.push({ col: startCol, row, count });
-            }
-            this._fullyCleared = false;
+            count++;
           }
+          col--;
+          if (imgSpec) {
+            if (imgSpec.actual) {
+              drawCalls.push({ imgSpec, tileId: startTile, col: startCol, row, count });
+            }
+          } else if (this._opts.showPlaceholder) {
+            placeholderCalls.push({ col: startCol, row, count });
+          }
+          this._fullyCleared = false;
         }
       }
     }
@@ -421,9 +513,9 @@ export class ImageStorage implements IDisposable {
     const rows = buffer.lines.length;
     const oldCol = this._viewportMetrics.cols - 1;
     for (let row = 0; row < rows; ++row) {
-      const line = buffer.lines.get(row)!;
-      const e = line.getExtended(oldCol)?.payload;
-      if (e instanceof ImageTileInfo) {
+      const line = buffer.lines.get(row) as IBufferLineExt;
+      if (line.getBg(oldCol) & BgFlags.HAS_EXTENDED) {
+        const e: IExtendedAttrsImage = line._extendedAttrs?.[oldCol] ?? EMPTY_ATTRS;
         const imageId = e.imageId;
         if (imageId === undefined || imageId === -1) {
           continue;
@@ -440,7 +532,7 @@ export class ImageStorage implements IDisposable {
         // expand only if right side is empty (nothing got wrapped from below)
         let hasData = false;
         for (let rightCol = oldCol + 1; rightCol > metrics.cols; ++rightCol) {
-          if (line.hasContent(rightCol)) {
+          if (line._data[rightCol * Cell.SIZE + Cell.CONTENT] & Content.HAS_CONTENT_MASK) {
             hasData = true;
             break;
           }
@@ -452,7 +544,7 @@ export class ImageStorage implements IDisposable {
         const end = Math.min(metrics.cols, tilesPerRow - (e.tileId % tilesPerRow) + oldCol);
         let lastTile = e.tileId;
         for (let expandCol = oldCol + 1; expandCol < end; ++expandCol) {
-          this._writeToCell(line, expandCol, imageId, ++lastTile);
+          this._writeToCell(line as IBufferLineExt, expandCol, imageId, ++lastTile);
           imgSpec.tileCount++;
         }
       }
@@ -466,10 +558,10 @@ export class ImageStorage implements IDisposable {
    */
   public getImageAtBufferCell(x: number, y: number): HTMLCanvasElement | undefined {
     const buffer = this._terminal._core.buffer;
-    const line = buffer.lines.get(y);
-    if (line) {
-      const e = line.getExtended(x)?.payload;
-      if (e instanceof ImageTileInfo && e.imageId && e.imageId !== -1) {
+    const line = buffer.lines.get(y) as IBufferLineExt;
+    if (line && line.getBg(x) & BgFlags.HAS_EXTENDED) {
+      const e: IExtendedAttrsImage = line._extendedAttrs?.[x] ?? EMPTY_ATTRS;
+      if (e.imageId && e.imageId !== -1) {
         const orig = this._images.get(e.imageId)?.orig;
         if (window.ImageBitmap && orig instanceof ImageBitmap) {
           const canvas = ImageRenderer.createCanvas(window.document, orig.width, orig.height);
@@ -486,10 +578,10 @@ export class ImageStorage implements IDisposable {
    */
   public extractTileAtBufferCell(x: number, y: number): HTMLCanvasElement | undefined {
     const buffer = this._terminal._core.buffer;
-    const line = buffer.lines.get(y);
-    if (line) {
-      const e = line.getExtended(x)?.payload;
-      if (e instanceof ImageTileInfo && e.imageId && e.imageId !== -1 && e.tileId !== -1) {
+    const line = buffer.lines.get(y) as IBufferLineExt;
+    if (line && line.getBg(x) & BgFlags.HAS_EXTENDED) {
+      const e: IExtendedAttrsImage = line._extendedAttrs?.[x] ?? EMPTY_ATTRS;
+      if (e.imageId && e.imageId !== -1 && e.tileId !== -1) {
         const spec = this._images.get(e.imageId);
         if (spec) {
           return this._renderer.extractTile(spec, e.tileId);
@@ -517,31 +609,31 @@ export class ImageStorage implements IDisposable {
     return used - current;
   }
 
-  private _writeToCell(line: IBufferLine, x: number, imageId: number, tileId: number): void {
-    const workCell = this._workCell;
-    line.loadCell(x, workCell);
-    if (this._workCell.hasExtendedAttrs()) {
-      const old = workCell.extended.payload;
-      if (old instanceof ImageTileInfo) {
-        // found an old ExtendedAttrsImage, since we know that
-        // they are always isolated instances (single cell usage),
-        // we can re-use it and just update their id entries
-        const oldSpec = this._images.get(old.imageId);
-        if (oldSpec) {
-          // early eviction for in-viewport overwrites
-          oldSpec.tileCount--;
+  private _writeToCell(line: IBufferLineExt, x: number, imageId: number, tileId: number): void {
+    if (line._data[x * Cell.SIZE + Cell.BG] & BgFlags.HAS_EXTENDED) {
+      const old = line._extendedAttrs?.[x];
+      if (old) {
+        if (old.imageId !== undefined) {
+          // found an old ExtendedAttrsImage, since we know that
+          // they are always isolated instances (single cell usage),
+          // we can re-use it and just update their id entries
+          const oldSpec = this._images.get(old.imageId);
+          if (oldSpec) {
+            // early eviction for in-viewport overwrites
+            oldSpec.tileCount--;
+          }
+          old.imageId = imageId;
+          old.tileId = tileId;
+          return;
         }
-        old.imageId = imageId;
-        old.tileId = tileId;
+        // found a plain ExtendedAttrs instance, clone it to new entry
+        (line._extendedAttrs ??= {})[x] = new ExtendedAttrsImage(old.ext, old.urlId, imageId, tileId);
         return;
       }
     }
-    // fall-through: always create new ExtendedAttrs entry
-    const extattr = workCell.extended.clone();
-    extattr.payload = new ImageTileInfo(imageId, tileId);
-    workCell.extended = extattr;
-    workCell.updateExtended();
-    line.setCell(x, workCell);
+    // fall-through: always create new ExtendedAttrsImage entry
+    line._data[x * Cell.SIZE + Cell.BG] |= BgFlags.HAS_EXTENDED;
+    (line._extendedAttrs ??= {})[x] = new ExtendedAttrsImage(0, 0, imageId, tileId);
   }
 
   private _evictOnAlternate(): void {
@@ -554,16 +646,18 @@ export class ImageStorage implements IDisposable {
     // re-count tiles on whole buffer
     const buffer = this._terminal._core.buffer;
     for (let y = 0; y < this._terminal.rows; ++y) {
-      const line = buffer.lines.get(y);
+      const line = buffer.lines.get(y) as IBufferLineExt;
       if (!line) {
         continue;
       }
       for (let x = 0; x < this._terminal.cols; ++x) {
-        const payload = line.getExtended(x)?.payload;
-        if (payload instanceof ImageTileInfo) {
-          const spec = this._images.get(payload.imageId);
-          if (spec) {
-            spec.tileCount++;
+        if (line._data[x * Cell.SIZE + Cell.BG] & BgFlags.HAS_EXTENDED) {
+          const imgId = line._extendedAttrs?.[x]?.imageId;
+          if (imgId) {
+            const spec = this._images.get(imgId);
+            if (spec) {
+              spec.tileCount++;
+            }
           }
         }
       }

addons/addon-image/src/Types.ts

@@ -10,6 +10,7 @@ import { Attributes, BgFlags, Content, ExtFlags, UnderlineStyle } from 'common/b
 import type { AttributeData } from 'common/buffer/AttributeData';
 import type { IParams, IDcsHandler, IOscHandler, IApcHandler, IEscapeSequenceParser } from 'common/parser/Types';
 import type { IInputHandler } from 'common/Types';
+import type { IBufferLine, IExtendedAttrs } from 'common/buffer/Types';
 import type { ITerminal, ReadonlyColorSet } from 'browser/Types';
 import type { IRenderDimensions } from 'browser/renderer/shared/Types';
 import type { ICoreBrowserService, IRenderService, IThemeService } from 'browser/services/Services';
@@ -47,7 +48,6 @@ export interface IResetHandler {
   reset(): void;
 }
 
-/* eslint-disable */
 /**
  * Stub into private interfaces.
  * This should be kept in line with common libs.
@@ -55,6 +55,19 @@ export interface IResetHandler {
  * have a somewhat reliable testing against code changes in the core repo.
  */
 
+// overloaded IExtendedAttrs to hold image refs
+export interface IExtendedAttrsImage extends IExtendedAttrs {
+  imageId: number;
+  tileId: number;
+  clone(): IExtendedAttrsImage;
+}
+
+/* eslint-disable */
+export interface IBufferLineExt extends IBufferLine {
+  _extendedAttrs: {[index: number]: IExtendedAttrsImage | undefined} | undefined;
+  _data: Uint32Array;
+}
+
 interface IInputHandlerExt extends IInputHandler {
   _parser: IEscapeSequenceParser;
   _curAttrData: AttributeData;
@@ -65,7 +78,6 @@ interface IInputHandlerExt extends IInputHandler {
   };
   onRequestReset(handler: () => void): IDisposable;
 }
-/* eslint-enable */
 
 export interface ICoreTerminalExt extends ITerminal {
   _themeService: IThemeService | undefined;
@@ -77,6 +89,8 @@ export interface ICoreTerminalExt extends ITerminal {
 export interface ITerminalExt extends Terminal {
   _core: ICoreTerminalExt;
 }
+/* eslint-enable */
+
 
 /**
  * Some storage definitions.

addons/addon-image/test/ImageAddon.test.ts

@@ -118,7 +118,10 @@ test.describe('ImageAddon', () => {
     }
     // bufferline privates
     strictEqual(await ctx.page.evaluate('window.term._core.buffer.lines.get(0)._data instanceof Uint32Array'), true);
-    strictEqual(await ctx.page.evaluate('window.term._core.buffer.lines.get(0)._extendedAttrs instanceof Object'), true);
+    strictEqual(await ctx.page.evaluate(`(() => {
+      const ea = window.term._core.buffer.lines.get(0)._extendedAttrs;
+      return ea === undefined || (typeof ea === 'object' && ea !== null);
+    })()`), true);
     // inputhandler privates
     strictEqual(await ctx.page.evaluate('window.term._core._inputHandler._curAttrData.constructor.name'), '_AttributeData');
     strictEqual(await ctx.page.evaluate('window.term._core._inputHandler._parser.constructor.name'), 'EscapeSequenceParser');
@@ -435,15 +438,6 @@ test.describe('ImageAddon', () => {
       });
     }
   });
-
-  test.describe('text overwrite removes tiles', () => {
-    test('sixel', async () => {
-      await assertTextClearsTiles(SIXEL_SEQ_0);
-    });
-    test('iip', async () => {
-      await assertTextClearsTiles(TESTDATA_IIP[0][0]);
-    });
-  });
 });
 
 /**
@@ -481,20 +475,3 @@ async function getOrigSize(id: number): Promise<[number, number]> {
 async function getImageAtBufferCell(x: number, y: number): Promise<string | undefined> {
   return ctx.page.evaluate<any>(`window.imageAddon.getImageAtBufferCell(${x}, ${y})?.toDataURL('image/png')`);
 }
-
-async function hasTileAtBufferCell(x: number, y: number): Promise<boolean> {
-  return ctx.page.evaluate(`!!window.imageAddon.extractTileAtBufferCell(${x}, ${y})`);
-}
-
-async function assertTextClearsTiles(imageSeq: string): Promise<void> {
-  await ctx.proxy.write('\x1b[H' + imageSeq);
-  await pollFor(ctx.page, '!!window.imageAddon.extractTileAtBufferCell(5, 1)', true);
-  ok(await hasTileAtBufferCell(0, 1));
-  await ctx.proxy.write('\x1b[2;6H#######');
-  for (let x = 5; x < 12; x++) {
-    strictEqual(await hasTileAtBufferCell(x, 1), false);
-  }
-  ok(await hasTileAtBufferCell(0, 1));
-  ok(await hasTileAtBufferCell(13, 1));
-  ok(((await ctx.page.evaluate('window.term.buffer.active.getLine(1).translateToString(true)')) as string).includes('#######'));
-}

addons/addon-image/test/KittyGraphics.test.ts

@@ -2213,21 +2213,6 @@ test.describe('Kitty Graphics Protocol', () => {
       await pollFor(ctx.page, 'window._imageAddedCount', 2);
     });
   });
-
-  test.describe('text overwrite removes tiles', () => {
-    test('a=T placement', async () => {
-      await ctx.proxy.write(`\x1b[H\x1b_Ga=T,f=100;${KITTY_MULTICOLOR_200X100_BASE64}\x1b\\`);
-      await pollFor(ctx.page, '!!window.imageAddon.extractTileAtBufferCell(5, 1)', true);
-      ok(await hasTileAtBufferCell(0, 1));
-      await ctx.proxy.write('\x1b[2;6H#######');
-      for (let x = 5; x < 12; x++) {
-        strictEqual(await hasTileAtBufferCell(x, 1), false);
-      }
-      ok(await hasTileAtBufferCell(0, 1));
-      ok(await hasTileAtBufferCell(13, 1));
-      ok(((await ctx.page.evaluate('window.term.buffer.active.getLine(1).translateToString(true)')) as string).includes('#######'));
-    });
-  });
 });
 
 /**
@@ -2277,7 +2262,3 @@ async function getPixels(col: number, row: number, x: number, y: number, w: numb
     return Array.from(ctx2d.getImageData(x, y, w, h).data);
   }, [col, row, x, y, w, h]);
 }
-
-async function hasTileAtBufferCell(x: number, y: number): Promise<boolean> {
-  return ctx.page.evaluate(`!!window.imageAddon.extractTileAtBufferCell(${x}, ${y})`);
-}

addons/addon-search/src/SearchAddon.ts

@@ -142,14 +142,12 @@ export class SearchAddon extends Disposable implements ITerminalAddon, ISearchAp
       }
       prevResult = result;
       results.push(prevResult);
-      const cols = this._terminal.cols;
-      let nextCol = prevResult.col + prevResult.size;
-      let nextRow = prevResult.row;
-      if (nextCol >= cols) {
-        nextRow += Math.floor(nextCol / cols);
-        nextCol = nextCol % cols;
-      }
-      result = this._engine.find(term, nextRow, nextCol, searchOptions);
+      result = this._engine.find(
+        term,
+        prevResult.col + prevResult.term.length >= this._terminal.cols ? prevResult.row + 1 : prevResult.row,
+        prevResult.col + prevResult.term.length >= this._terminal.cols ? 0 : prevResult.col + 1,
+        searchOptions
+      );
     }
 
     this._resultTracker.updateResults(results, this._highlightLimit);

addons/addon-search/test/SearchAddon.test.ts

@@ -414,20 +414,6 @@ test.describe('Search Tests', () => {
   });
 
   test.describe('Regression tests', () => {
-    test('should advance highlight-all scan by buffer match size for wide characters', async () => {
-      await ctx.page.evaluate(`
-        window.calls = [];
-        window.search.onDidChangeResults(e => window.calls.push(e));
-      `);
-      await ctx.proxy.resize(3, 5);
-      await ctx.proxy.write('𝄞𝄞𝄞');
-      strictEqual(await ctx.page.evaluate(`window.search.findNext('𝄞', { decorations: { activeMatchColorOverviewRuler: '#ff0000', matchOverviewRuler: '#ffff00' } })`), true);
-      deepStrictEqual(await ctx.page.evaluate('window.calls'), [
-        { resultCount: 3, resultIndex: 0 }
-      ]);
-      await ctx.proxy.resize(80, 24);
-    });
-
     test.describe('#2444 wrapped line content not being found', () => {
       let fixture: string;
       test.beforeAll(async () => {

addons/addon-webgl/src/GlyphRenderer.ts

@@ -100,8 +100,6 @@ export class GlyphRenderer extends Disposable {
   private readonly _attributesBuffer: WebGLBuffer;
 
   private _atlas: ITextureAtlas | undefined;
-  private _lastSeenPageLayoutVersion: number = -1;
-  private _pageOverflowWarned: boolean = false;
   private _activeBuffer: number = 0;
   private readonly _vertices: IVertices = {
     count: 0,
@@ -215,19 +213,8 @@ export class GlyphRenderer extends Disposable {
     this.handleResize();
   }
 
-  /**
-   * Call when a frame is being drawn. Returns whether the full model must be rebuilt before
-   * rendering this frame because the atlas page layout changed since this renderer last drew.
-   */
   public beginFrame(): boolean {
-    if (!this._atlas) {
-      return true;
-    }
-    if (this._atlas.pageLayoutVersion !== this._lastSeenPageLayoutVersion) {
-      this._lastSeenPageLayoutVersion = this._atlas.pageLayoutVersion;
-      return true;
-    }
-    return false;
+    return this._atlas ? this._atlas.beginFrame() : true;
   }
 
   public updateCell(x: number, y: number, code: number, bg: number, fg: number, ext: number, chars: string, width: number, lastBg: number): void {
@@ -376,13 +363,7 @@ export class GlyphRenderer extends Disposable {
     // Bind the atlas page texture if they have changed. AtlasPage.version is globally
     // monotonic, so a page object swap at the same index (which happens after a page merge)
     // is detected by the same comparison.
-    // Clamp defensively in case the atlas unexpectedly exceeds texture capacity.
-    const pageCount = Math.min(this._atlas.pages.length, this._atlasTextures.length);
-    if (this._atlas.pages.length > this._atlasTextures.length && !this._pageOverflowWarned) {
-      this._pageOverflowWarned = true;
-      this._logService.warn(`Atlas page count (${this._atlas.pages.length}) exceeds the renderer's texture capacity (${this._atlasTextures.length}), some glyphs will not render correctly`);
-    }
-    for (let i = 0; i < pageCount; i++) {
+    for (let i = 0; i < this._atlas.pages.length; i++) {
       if (this._atlas.pages[i].version !== this._atlasTextures[i].version) {
         this._bindAtlasPageTexture(gl, this._atlas, i);
       }
@@ -394,7 +375,6 @@ export class GlyphRenderer extends Disposable {
 
   public setAtlas(atlas: ITextureAtlas): void {
     this._atlas = atlas;
-    this._lastSeenPageLayoutVersion = -1;
     this.invalidateAtlasTextures();
   }
 

addons/addon-webgl/src/TextureAtlas.ts

@@ -132,8 +132,12 @@ export class TextureAtlas implements ITextureAtlas {
     }
   }
 
-  private _pageLayoutVersion = 0;
-  public get pageLayoutVersion(): number { return this._pageLayoutVersion; }
+  private _requestClearModel = false;
+  public beginFrame(): boolean {
+    const result = this._requestClearModel;
+    this._requestClearModel = false;
+    return result;
+  }
 
   public clearTexture(): void {
     if (this._pages[0].currentRow.x === 0 && this._pages[0].currentRow.y === 0) {
@@ -145,11 +149,6 @@ export class TextureAtlas implements ITextureAtlas {
     this._cacheMap.clear();
     this._cacheMapCombined.clear();
     this._didWarmUp = false;
-
-    // Invalidate renderer models so all texture pages are refreshed. The atlas may be shared, in
-    // which case the clearing renderer has cleared only its own model and every other owner still
-    // holds texture coords into the rows just wiped.
-    this._pageLayoutVersion++;
   }
 
   private _createNewPage(): AtlasPage {
@@ -185,8 +184,6 @@ export class TextureAtlas implements ITextureAtlas {
       // Only proceed with merge if we have exactly 4 same-sized pages. If not, we cannot
       // effectively reduce page count and merging would cause issues.
       if (mergingPages.length < 4 || mergingPages.some(p => p.canvas.width !== mergingPages[0].canvas.width)) {
-        // Evict instead of adding a page beyond the renderer's texture capacity.
-        this._evictAllPages();
         const newPage = new AtlasPage(this._document, this._textureSize);
         this._pages.push(newPage);
         this._activePages.push(newPage);
@@ -209,8 +206,8 @@ export class TextureAtlas implements ITextureAtlas {
       // Add the new merged page to the end
       this.pages.push(mergedPage);
 
-      // Invalidate renderer models so all texture pages are refreshed.
-      this._pageLayoutVersion++;
+      // Request the model to be cleared to refresh all texture pages.
+      this._requestClearModel = true;
       this._onAddTextureAtlasCanvas.fire(mergedPage.canvas);
     }
 
@@ -261,23 +258,6 @@ export class TextureAtlas implements ITextureAtlas {
     }
   }
 
-  private _evictAllPages(): void {
-    const startTime = performance.now();
-    const pageCount = this._pages.length;
-    for (const page of this._pages) {
-      this._onRemoveTextureAtlasCanvas.fire(page.canvas);
-      page.canvas.remove();
-    }
-    this._pages.length = 0;
-    this._activePages.length = 0;
-    this._overflowSizePage = undefined;
-    this._cacheMap.clear();
-    this._cacheMapCombined.clear();
-    this._didWarmUp = false;
-    this._pageLayoutVersion++;
-    this._logService.debug(`Evicted ${pageCount} WebGL atlas pages in ${(performance.now() - startTime).toFixed(2)}ms`);
-  }
-
   public getRasterizedGlyphCombinedChar(chars: string, bg: number, fg: number, ext: number, restrictToCellHeight: boolean, domContainer: HTMLElement | undefined): IRasterizedGlyph {
     return this._getFromCacheMap(this._cacheMapCombined, chars, bg, fg, ext, restrictToCellHeight, domContainer);
   }
@@ -835,15 +815,11 @@ export class TextureAtlas implements ITextureAtlas {
       // Create a new page for oversized glyphs as they come up
       if (rasterizedGlyph.size.x > this._textureSize) {
         if (!this._overflowSizePage) {
-          // Make room for the oversized page without exceeding texture capacity.
-          if (TextureAtlas.maxAtlasPages && this._pages.length >= TextureAtlas.maxAtlasPages) {
-            this._evictAllPages();
-          }
           this._overflowSizePage = new AtlasPage(this._document, this._config.deviceMaxTextureSize);
           this.pages.push(this._overflowSizePage);
 
-          // Invalidate renderer models so all texture pages are refreshed.
-          this._pageLayoutVersion++;
+          // Request the model to be cleared to refresh all texture pages.
+          this._requestClearModel = true;
           this._onAddTextureAtlasCanvas.fire(this._overflowSizePage.canvas);
         }
         activePage = this._overflowSizePage;

addons/addon-webgl/src/Types.ts

@@ -68,12 +68,10 @@ export interface ITextureAtlas extends IDisposable {
   warmUp(): void;
 
   /**
-   * Incremented whenever cached glyph texture page mappings may be stale, such as after atlas page
-   * merges or overflow page creation. Renderers compare this against their own last-seen value and
-   * rebuild their model when it changes; a shared atlas can have many renderers, so this must not
-   * be a consume-once flag.
+   * Call when a frame is being drawn, this will return true if the atlas was cleared to make room
+   * for a new set of glyphs.
    */
-  readonly pageLayoutVersion: number;
+  beginFrame(): boolean;
 
   /**
    * Clear all glyphs from the texture atlas.

addons/addon-webgl/src/customGlyphs/CustomGlyphRasterizer.test.ts

@@ -1,54 +0,0 @@
-/**
- * Copyright (c) 2026 The xterm.js authors. All rights reserved.
- * @license MIT
- */
-
-import { assert } from 'chai';
-import { createPatternCanvas } from './CustomGlyphRasterizer';
-
-describe('CustomGlyphRasterizer', () => {
-  describe('createPatternCanvas', () => {
-    it('prefers an offscreen canvas without using the DOM canvas factory', () => {
-      const expectedCanvas = {} as OffscreenCanvas;
-      const calls: string[] = [];
-
-      const canvas = createPatternCanvas(
-        2,
-        3,
-        (width, height) => {
-          calls.push(`offscreen:${width}x${height}`);
-          return expectedCanvas;
-        },
-        () => {
-          calls.push('dom');
-          return {} as HTMLCanvasElement;
-        }
-      );
-
-      assert.deepEqual({ canvas, calls }, {
-        canvas: expectedCanvas,
-        calls: ['offscreen:2x3']
-      });
-    });
-
-    it('uses the main-realm DOM canvas factory when OffscreenCanvas is unavailable', () => {
-      const expectedCanvas = {} as HTMLCanvasElement;
-      const calls: string[] = [];
-
-      const canvas = createPatternCanvas(
-        4,
-        5,
-        undefined,
-        (width, height) => {
-          calls.push(`dom:${width}x${height}`);
-          return expectedCanvas;
-        }
-      );
-
-      assert.deepEqual({ canvas, calls }, {
-        canvas: expectedCanvas,
-        calls: ['dom:4x5']
-      });
-    });
-  });
-});

addons/addon-webgl/src/customGlyphs/CustomGlyphRasterizer.ts

@@ -8,29 +8,6 @@ import type { ILogService } from 'common/services/Services';
 import { customGlyphDefinitions } from './CustomGlyphDefinitions';
 import { CustomGlyphDefinitionType, CustomGlyphScaleType, CustomGlyphVectorType, type CustomGlyphDefinitionPart, type CustomGlyphPathDrawFunctionDefinition, type CustomGlyphPatternDefinition, type ICustomGlyphSolidOctantBlockVector, type ICustomGlyphVectorShape } from './Types';
 
-type PatternCanvas = HTMLCanvasElement | OffscreenCanvas;
-type PatternCanvasFactory = (width: number, height: number) => PatternCanvas;
-
-const createOffscreenPatternCanvas: PatternCanvasFactory | undefined = typeof OffscreenCanvas === 'undefined'
-  ? undefined
-  : (width, height) => new OffscreenCanvas(width, height);
-
-const createDomPatternCanvas: PatternCanvasFactory = (width, height) => {
-  const canvas = document.createElement('canvas');
-  canvas.width = width;
-  canvas.height = height;
-  return canvas;
-};
-
-export function createPatternCanvas(
-  width: number,
-  height: number,
-  offscreenCanvasFactory: PatternCanvasFactory | undefined = createOffscreenPatternCanvas,
-  domCanvasFactory: PatternCanvasFactory = createDomPatternCanvas
-): PatternCanvas {
-  return offscreenCanvasFactory?.(width, height) ?? domCanvasFactory(width, height);
-}
-
 /**
  * Try drawing a custom block element or box drawing character, returning whether it was
  * successfully drawn.
@@ -481,9 +458,9 @@ function drawPatternChar(
   if (!pattern) {
     const width = charDefinition[0].length;
     const height = charDefinition.length;
-    // The atlas canvas can be adopted into another document, so temporary resources must not use
-    // its mutable ownerDocument.
-    const tmpCanvas = createPatternCanvas(width, height);
+    const tmpCanvas = ctx.canvas.ownerDocument.createElement('canvas');
+    tmpCanvas.width = width;
+    tmpCanvas.height = height;
     const tmpCtx = throwIfFalsy(tmpCanvas.getContext('2d'));
     const imageData = new ImageData(width, height);
 

addons/addon-webgl/test/WebglAtlasOverflow.test.ts

@@ -1,481 +0,0 @@
-/**
- * Copyright (c) 2025 The xterm.js authors. All rights reserved.
- * @license MIT
- */
-
-import { IImage32, decodePng } from '@lunapaint/png-codec';
-import test, { expect } from '@playwright/test';
-import type { Terminal, ITerminalInitOnlyOptions, ITerminalOptions } from '@xterm/xterm';
-import type { IWebglAddonOptions, WebglAddon } from '@xterm/addon-webgl';
-import { ITestContext, createTestContext, openTerminal } from '../../../test/playwright/TestUtils';
-
-type CellSignature = number[];
-type TestTerminalConstructor = new (options?: ITerminalOptions & ITerminalInitOnlyOptions) => ITestTerminal;
-type TestWebglAddonConstructor = new (options?: IWebglAddonOptions) => ITestWebglAddon;
-
-interface ITestTextureAtlasConstructor {
-  maxAtlasPages: number | undefined;
-  maxTextureSize: number | undefined;
-}
-
-interface ITestAtlasPage {
-  canvas: HTMLCanvasElement;
-}
-
-interface ITestTextureAtlas {
-  constructor: ITestTextureAtlasConstructor;
-  pages: ITestAtlasPage[];
-  pageLayoutVersion: number;
-  _overflowSizePage?: ITestAtlasPage;
-  _textureSize: number;
-}
-
-interface ITestGlyphRenderer {
-  _atlasTextures: unknown[];
-}
-
-interface ITestRenderer {
-  _charAtlas?: ITestTextureAtlas;
-  _glyphRenderer?: {
-    value?: ITestGlyphRenderer;
-  };
-  dimensions: {
-    device: {
-      cell: {
-        width: number;
-      };
-    };
-  };
-}
-
-interface ITestRenderService {
-  _renderer?: {
-    value?: ITestRenderer;
-  };
-}
-
-interface ITestTerminal extends Terminal {
-  _core?: {
-    _renderService?: ITestRenderService;
-  };
-}
-
-interface ITestWebglAddon extends WebglAddon {
-  _renderer?: ITestRenderer;
-}
-
-interface IAtlasEventStats {
-  removals: number;
-  maxPages: number;
-}
-
-interface ITestWindow extends Window {
-  Terminal: TestTerminalConstructor;
-  WebglAddon: TestWebglAddonConstructor;
-  term: ITestTerminal;
-  termB?: ITestTerminal;
-  addon?: ITestWebglAddon;
-  addonB?: ITestWebglAddon;
-  atlasEventStats?: IAtlasEventStats;
-}
-
-interface IAtlasLimits {
-  maxAtlasPages: number;
-  maxTextureSize: number;
-}
-
-interface IAtlasState {
-  pages: number;
-  atlasTextures: number;
-  pageLayoutVersion: number;
-  overflowPageCreated: boolean;
-  removals: number;
-  maxPages: number;
-}
-
-const NORMAL_HEADER = ' NORMAL_REF_0123456789';
-const POST_EVICTION_TEXT = ' AFTER_EVICTION_0123456789';
-const NORMAL_HEADER_COLS = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
-const POST_EVICTION_COLS = [2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
-const TERM_B_SELECTOR = '#terminal-container-b .xterm-screen';
-const TERM_SELECTOR = '#terminal-container .xterm-screen';
-
-async function loadWebglStrict(ctx: ITestContext): Promise<void> {
-  await ctx.page.evaluate(() => {
-    const w = window as unknown as ITestWindow;
-    w.addon = new w.WebglAddon({ preserveDrawingBuffer: true });
-    w.term.loadAddon(w.addon);
-  });
-  const isWebglRenderer = await ctx.page.evaluate(() => {
-    const w = window as unknown as ITestWindow;
-    return !!w.addon && w.term._core?._renderService?._renderer?.value === w.addon._renderer;
-  });
-  expect(isWebglRenderer, 'WebGL renderer must be active').toBe(true);
-}
-
-async function createTerminalB(ctx: ITestContext, cols: number): Promise<void> {
-  await ctx.page.evaluate(columnCount => {
-    const w = window as unknown as ITestWindow;
-    w.termB?.dispose();
-    document.getElementById('terminal-container-b')?.remove();
-    const element = document.createElement('div');
-    element.id = 'terminal-container-b';
-    document.body.appendChild(element);
-    w.termB = new w.Terminal({ cols: columnCount, rows: 24, allowProposedApi: true });
-    w.termB.open(element);
-    w.addonB = new w.WebglAddon({ preserveDrawingBuffer: true });
-    w.termB.loadAddon(w.addonB);
-  }, cols);
-}
-
-async function writeToBAndWaitForRender(ctx: ITestContext, data: string): Promise<void> {
-  await ctx.page.evaluate(value => new Promise<void>(resolve => {
-    const w = window as unknown as ITestWindow;
-    if (!w.termB) {
-      throw new Error('Terminal B must be created before writing to it');
-    }
-    const disposable = w.termB.onRender(() => {
-      disposable.dispose();
-      resolve();
-    });
-    w.termB.write(value);
-  }), data);
-}
-
-async function writeAndWaitForRender(ctx: ITestContext, data: string): Promise<void> {
-  const renderPromise = new Promise<void>(resolve => {
-    const disposable = ctx.proxy.onRender(() => {
-      disposable.dispose();
-      resolve();
-    });
-  });
-  await ctx.proxy.write(data);
-  await renderPromise;
-}
-
-async function refreshAndWaitForRender(ctx: ITestContext, terminal: 'term' | 'termB'): Promise<void> {
-  await ctx.page.evaluate(name => new Promise<void>(resolve => {
-    const w = window as unknown as ITestWindow;
-    const term = w[name];
-    if (!term) {
-      throw new Error(`${name} must exist before refreshing it`);
-    }
-    const disposable = term.onRender(() => {
-      disposable.dispose();
-      resolve();
-    });
-    term.refresh(0, term.rows - 1);
-  }), terminal);
-}
-
-async function configureAtlasLimits(ctx: ITestContext): Promise<IAtlasLimits> {
-  const limits = await ctx.page.evaluate(() => {
-    const w = window as unknown as ITestWindow;
-    const atlas = w.term._core?._renderService?._renderer?.value?._charAtlas;
-    if (!atlas || atlas.constructor.maxAtlasPages === undefined || atlas.constructor.maxTextureSize === undefined) {
-      return undefined;
-    }
-    const result = {
-      maxAtlasPages: atlas.constructor.maxAtlasPages,
-      maxTextureSize: atlas.constructor.maxTextureSize
-    };
-    atlas.constructor.maxAtlasPages = 4;
-    atlas.constructor.maxTextureSize = 512;
-    return result;
-  });
-  expect(limits, 'TextureAtlas limits must be initialized').toBeDefined();
-  return limits!;
-}
-
-async function restoreAtlasLimits(ctx: ITestContext, limits: IAtlasLimits | undefined): Promise<void> {
-  if (!limits) {
-    return;
-  }
-  await ctx.page.evaluate(original => {
-    const w = window as unknown as ITestWindow;
-    const atlas = w.term._core?._renderService?._renderer?.value?._charAtlas;
-    if (atlas) {
-      atlas.constructor.maxAtlasPages = original.maxAtlasPages;
-      atlas.constructor.maxTextureSize = original.maxTextureSize;
-    }
-  }, limits);
-}
-
-async function installAtlasEventStats(ctx: ITestContext): Promise<void> {
-  const installed = await ctx.page.evaluate(() => {
-    const w = window as unknown as ITestWindow;
-    const atlas = w.term._core?._renderService?._renderer?.value?._charAtlas;
-    if (!atlas || !w.addon) {
-      return false;
-    }
-    const stats: IAtlasEventStats = {
-      removals: 0,
-      maxPages: atlas.pages.length
-    };
-    w.atlasEventStats = stats;
-    w.addon.onAddTextureAtlasCanvas(() => {
-      stats.maxPages = Math.max(stats.maxPages, atlas.pages.length);
-    });
-    w.addon.onRemoveTextureAtlasCanvas(() => stats.removals++);
-    return true;
-  });
-  expect(installed, 'atlas event tracking must be installed').toBe(true);
-}
-
-async function getAtlasState(ctx: ITestContext): Promise<IAtlasState> {
-  const state = await ctx.page.evaluate(() => {
-    const w = window as unknown as ITestWindow;
-    const renderer = w.term._core?._renderService?._renderer?.value;
-    const atlas = renderer?._charAtlas;
-    const glyphRenderer = renderer?._glyphRenderer?.value;
-    const stats = w.atlasEventStats;
-    if (!atlas || !glyphRenderer || !stats) {
-      return undefined;
-    }
-    return {
-      pages: atlas.pages.length,
-      atlasTextures: glyphRenderer._atlasTextures.length,
-      pageLayoutVersion: atlas.pageLayoutVersion,
-      overflowPageCreated: !!atlas._overflowSizePage,
-      removals: stats.removals,
-      maxPages: stats.maxPages
-    };
-  });
-  expect(state, 'atlas state must be available').toBeDefined();
-  return state!;
-}
-
-function generateUniqueGlyphFlood(count: number, cols: number, offset: number): string {
-  const base = 0x4E00;
-  const range = 0x9FFF - base;
-  const perRow = Math.max(1, Math.floor(cols / 2));
-  let result = '';
-  for (let i = 0; i < count; i++) {
-    result += String.fromCodePoint(base + ((offset + i) % range));
-    if ((i + 1) % perRow === 0 && i + 1 < count) {
-      result += '\r\n';
-    }
-  }
-  return result;
-}
-
-async function captureRowSignatures(ctx: ITestContext, selector: string, cols: number, row: number, sampleCols: number[], debugName: string): Promise<CellSignature[]> {
-  const screenshotOptions = process.env.DEBUG ? { path: `out-esbuild-test/playwright/${debugName}.png` } : undefined;
-  const buffer = await ctx.page.locator(selector).screenshot(screenshotOptions);
-  const frame = {
-    cols,
-    rows: 24,
-    decoded: (await decodePng(new Uint8Array(buffer), { force32: true })).image
-  };
-  return sampleCols.map(col => cellSignature(frame, col, row));
-}
-
-function cellSignature(frame: { cols: number, rows: number, decoded: IImage32 }, col: number, row: number): CellSignature {
-  const grid = 4;
-  const data = frame.decoded.data;
-  const imageWidth = frame.decoded.width;
-  const cellWidth = frame.decoded.width / frame.cols;
-  const cellHeight = frame.decoded.height / frame.rows;
-  const x0 = (col - 1) * cellWidth;
-  const y0 = (row - 1) * cellHeight;
-  const sums = new Array<number>(grid * grid * 4).fill(0);
-  const counts = new Array<number>(grid * grid).fill(0);
-  const startX = Math.max(0, Math.floor(x0));
-  const startY = Math.max(0, Math.floor(y0));
-  const endX = Math.min(frame.decoded.width, Math.ceil(x0 + cellWidth));
-  const endY = Math.min(frame.decoded.height, Math.ceil(y0 + cellHeight));
-
-  for (let y = startY; y < endY; y++) {
-    const gy = Math.min(grid - 1, Math.max(0, Math.floor(((y - y0) / cellHeight) * grid)));
-    for (let x = startX; x < endX; x++) {
-      const gx = Math.min(grid - 1, Math.max(0, Math.floor(((x - x0) / cellWidth) * grid)));
-      const sub = gy * grid + gx;
-      const i = (y * imageWidth + x) * 4;
-      sums[sub * 4] += data[i];
-      sums[sub * 4 + 1] += data[i + 1];
-      sums[sub * 4 + 2] += data[i + 2];
-      sums[sub * 4 + 3] += data[i + 3];
-      counts[sub]++;
-    }
-  }
-
-  const signature = new Array<number>(grid * grid * 4).fill(0);
-  for (let sub = 0; sub < counts.length; sub++) {
-    if (counts[sub] > 0) {
-      signature[sub * 4] = sums[sub * 4] / counts[sub];
-      signature[sub * 4 + 1] = sums[sub * 4 + 1] / counts[sub];
-      signature[sub * 4 + 2] = sums[sub * 4 + 2] / counts[sub];
-      signature[sub * 4 + 3] = sums[sub * 4 + 3] / counts[sub];
-    }
-  }
-  return signature;
-}
-
-function signatureDiff(actual: CellSignature, reference: CellSignature): number {
-  let diff = 0;
-  for (let i = 0; i < actual.length; i++) {
-    diff = Math.max(diff, Math.abs(actual[i] - reference[i]));
-  }
-  return diff;
-}
-
-function expectSignatureMatches(actual: CellSignature, reference: CellSignature, message: string): void {
-  const diff = signatureDiff(actual, reference);
-  expect(diff, `${message}; max channel diff ${diff}`).toBeLessThanOrEqual(14);
-}
-
-test.describe('atlas page overflow (#6038)', () => {
-  test.skip(({ browserName }) => browserName !== 'chromium');
-  test.describe.configure({ timeout: 90000 });
-
-  test('evicts normal pages when the page cap cannot be reduced by merging', async ({ browser }) => {
-    const ctx = await createTestContext(browser);
-    const errors: string[] = [];
-    const onError = (error: Error): void => { errors.push(error.message); };
-    let limits: IAtlasLimits | undefined;
-    ctx.page.on('pageerror', onError);
-    try {
-      await openTerminal(ctx, { cols: 80, rows: 24 });
-      await loadWebglStrict(ctx);
-      limits = await configureAtlasLimits(ctx);
-
-      await openTerminal(ctx, { cols: 80, rows: 24 });
-      await loadWebglStrict(ctx);
-      await createTerminalB(ctx, 80);
-      await installAtlasEventStats(ctx);
-
-      const atlasShared = await ctx.page.evaluate(() => {
-        const w = window as unknown as ITestWindow;
-        return w.term._core?._renderService?._renderer?.value?._charAtlas === w.termB?._core?._renderService?._renderer?.value?._charAtlas;
-      });
-      expect(atlasShared, 'terminals with equal configs should share one texture atlas').toBe(true);
-
-      await writeToBAndWaitForRender(ctx, `\x1b[H${NORMAL_HEADER}\x1b[2;1H${POST_EVICTION_TEXT}`);
-      const headerReference = await captureRowSignatures(ctx, TERM_B_SELECTOR, 80, 1, NORMAL_HEADER_COLS, 'atlas-overflow-header-reference');
-      const postReference = await captureRowSignatures(ctx, TERM_B_SELECTOR, 80, 2, POST_EVICTION_COLS, 'atlas-overflow-post-reference');
-      await writeToBAndWaitForRender(ctx, '\x1b[2;1H\x1b[2K');
-
-      const initialState = await getAtlasState(ctx);
-      const glyphsPerChunk = 23 * 40 - 1;
-      for (let chunk = 0; chunk < 24; chunk++) {
-        await ctx.proxy.write('\x1b[H\x1b[2J' + generateUniqueGlyphFlood(glyphsPerChunk, 80, chunk * glyphsPerChunk));
-        await ctx.page.waitForTimeout(50);
-        const state = await getAtlasState(ctx);
-        if (state.removals > 0 || state.pages > state.atlasTextures || errors.length > 0) {
-          break;
-        }
-      }
-
-      const evictionState = await getAtlasState(ctx);
-      expect(evictionState.removals, 'normal atlas pages must be evicted at the page cap').toBeGreaterThan(0);
-      expect(evictionState.pageLayoutVersion, 'eviction must invalidate renderer models').toBeGreaterThan(initialState.pageLayoutVersion);
-      expect(evictionState.maxPages, 'atlas pages must stay within renderer texture capacity').toBeLessThanOrEqual(evictionState.atlasTextures);
-      expect(errors, `renderer must not throw during atlas eviction: ${errors[0] ?? ''}`).toEqual([]);
-
-      await writeToBAndWaitForRender(ctx, `\x1b[2;1H${POST_EVICTION_TEXT}`);
-      const termBHeader = await ctx.page.evaluate(() => {
-        const w = window as unknown as ITestWindow;
-        return w.termB?.buffer.active.getLine(0)?.translateToString(true);
-      });
-      expect(termBHeader, 'terminal B buffer must still contain the header').toBe(NORMAL_HEADER);
-
-      const headerAfter = await captureRowSignatures(ctx, TERM_B_SELECTOR, 80, 1, NORMAL_HEADER_COLS, 'atlas-overflow-header-after');
-      const postAfter = await captureRowSignatures(ctx, TERM_B_SELECTOR, 80, 2, POST_EVICTION_COLS, 'atlas-overflow-post-after');
-      for (let i = 0; i < NORMAL_HEADER_COLS.length; i++) {
-        expectSignatureMatches(headerAfter[i], headerReference[i], `existing header col ${NORMAL_HEADER_COLS[i]} changed after eviction`);
-      }
-      for (let i = 0; i < POST_EVICTION_COLS.length; i++) {
-        expectSignatureMatches(postAfter[i], postReference[i], `new text col ${POST_EVICTION_COLS[i]} changed after eviction`);
-      }
-
-      const stableState = await getAtlasState(ctx);
-      await refreshAndWaitForRender(ctx, 'termB');
-      const refreshedState = await getAtlasState(ctx);
-      expect(refreshedState.pageLayoutVersion, 'an unchanged full refresh must not evict again').toBe(stableState.pageLayoutVersion);
-      expect(refreshedState.removals, 'an unchanged full refresh must not remove more pages').toBe(stableState.removals);
-    } finally {
-      ctx.page.off('pageerror', onError);
-      await restoreAtlasLimits(ctx, limits).catch(() => {});
-      await ctx.page.close();
-    }
-  });
-
-  test('evicts before adding an oversized glyph page at the page cap', async ({ browser }) => {
-    const ctx = await createTestContext(browser);
-    const errors: string[] = [];
-    const onError = (error: Error): void => { errors.push(error.message); };
-    let limits: IAtlasLimits | undefined;
-    ctx.page.on('pageerror', onError);
-    try {
-      await openTerminal(ctx, { cols: 160, rows: 24 });
-      await loadWebglStrict(ctx);
-      limits = await configureAtlasLimits(ctx);
-
-      await openTerminal(ctx, { cols: 160, rows: 24 });
-      await loadWebglStrict(ctx);
-      await installAtlasEventStats(ctx);
-
-      let state = await getAtlasState(ctx);
-      let offset = 0;
-      for (let chunk = 0; chunk < 120 && state.pages < state.atlasTextures; chunk++) {
-        const glyphCount = state.pages < state.atlasTextures - 1 ? 200 : 25;
-        await ctx.proxy.write('\x1b[H\x1b[2J' + generateUniqueGlyphFlood(glyphCount, 160, offset));
-        await ctx.page.waitForTimeout(50);
-        offset += glyphCount;
-        state = await getAtlasState(ctx);
-      }
-      expect(state.pages, 'normal atlas pages must reach the texture capacity before the oversized glyph').toBe(state.atlasTextures);
-      expect(state.overflowPageCreated, 'normal glyph filling must not create the oversized page').toBe(false);
-      expect(errors, `renderer must not fail while filling normal pages: ${errors[0] ?? ''}`).toEqual([]);
-
-      await writeAndWaitForRender(ctx, '\x1b[H\x1b[2K\x1b[24;1H');
-      const sampleCols = [1, 8, 16, 24, 32];
-      const blankSignatures = await captureRowSignatures(ctx, TERM_SELECTOR, 160, 1, sampleCols, 'atlas-overflow-wide-blank');
-      const joinedLength = await ctx.page.evaluate(() => {
-        const w = window as unknown as ITestWindow;
-        const renderer = w.term._core?._renderService?._renderer?.value;
-        const atlas = renderer?._charAtlas;
-        if (!renderer || !atlas) {
-          throw new Error('renderer and atlas must exist');
-        }
-        const cellWidth = renderer.dimensions.device.cell.width;
-        const length = Math.min(w.term.cols - 1, Math.ceil(atlas._textureSize / cellWidth) + 32);
-        if (length * cellWidth <= atlas._textureSize) {
-          throw new Error('joined glyph must be wider than a normal atlas page');
-        }
-        const marker = 'W'.repeat(length);
-        w.term.registerCharacterJoiner(text => text.startsWith(marker) ? [[0, length]] : []);
-        return length;
-      });
-
-      const beforeOversized = await getAtlasState(ctx);
-      await ctx.proxy.write(`\x1b[H${'W'.repeat(joinedLength)}`);
-      await ctx.page.waitForTimeout(50);
-      const oversizedState = await getAtlasState(ctx);
-      expect(oversizedState.overflowPageCreated, 'the joined glyph must use the oversized atlas page').toBe(true);
-      expect(oversizedState.removals, 'normal pages must be evicted before adding the oversized page').toBeGreaterThan(beforeOversized.removals);
-      expect(oversizedState.maxPages, 'oversized page creation must stay within renderer texture capacity').toBeLessThanOrEqual(oversizedState.atlasTextures);
-      expect(oversizedState.pageLayoutVersion, 'oversized eviction must invalidate renderer models').toBeGreaterThan(beforeOversized.pageLayoutVersion);
-      expect(errors, `renderer must not throw while adding the oversized page: ${errors[0] ?? ''}`).toEqual([]);
-
-      const wideSignatures = await captureRowSignatures(ctx, TERM_SELECTOR, 160, 1, sampleCols, 'atlas-overflow-wide-after');
-      for (let i = 0; i < sampleCols.length; i++) {
-        expect(signatureDiff(wideSignatures[i], blankSignatures[i]), `wide glyph col ${sampleCols[i]} must render visible pixels`).toBeGreaterThan(14);
-      }
-
-      const stableState = await getAtlasState(ctx);
-      await refreshAndWaitForRender(ctx, 'term');
-      const refreshedState = await getAtlasState(ctx);
-      expect(refreshedState.pageLayoutVersion, 'oversized glyph refresh must settle without another eviction').toBe(stableState.pageLayoutVersion);
-      expect(refreshedState.removals, 'oversized glyph refresh must not remove more pages').toBe(stableState.removals);
-      const wideAfterRefresh = await captureRowSignatures(ctx, TERM_SELECTOR, 160, 1, sampleCols, 'atlas-overflow-wide-refreshed');
-      for (let i = 0; i < sampleCols.length; i++) {
-        expectSignatureMatches(wideAfterRefresh[i], wideSignatures[i], `wide glyph col ${sampleCols[i]} changed after refresh`);
-      }
-    } finally {
-      ctx.page.off('pageerror', onError);
-      await restoreAtlasLimits(ctx, limits).catch(() => {});
-      await ctx.page.close();
-    }
-  });
-});

addons/addon-webgl/test/WebglAtlasStress.test.ts

@@ -1,288 +0,0 @@
-/**
- * Copyright (c) 2025 The xterm.js authors. All rights reserved.
- * @license MIT
- */
-
-import { decodePng, type IImage32 } from '@lunapaint/png-codec';
-import test, { expect } from '@playwright/test';
-import type { Terminal, ITerminalInitOnlyOptions, ITerminalOptions } from '@xterm/xterm';
-import type { IWebglAddonOptions, WebglAddon } from '@xterm/addon-webgl';
-import { ITestContext, createTestContext, openTerminal } from '../../../test/playwright/TestUtils';
-
-type CellSignature = number[];
-type TestTerminalConstructor = new (options?: ITerminalOptions & ITerminalInitOnlyOptions) => ITestTerminal;
-type TestWebglAddonConstructor = new (options?: IWebglAddonOptions) => ITestWebglAddon;
-
-interface ITestTextureAtlas {
-  readonly pages: ReadonlyArray<{ readonly canvas: HTMLCanvasElement }>;
-}
-
-interface ITestGlyphRenderer {
-  readonly _atlasTextures: ReadonlyArray<unknown>;
-}
-
-interface ITestRenderer {
-  _charAtlas?: ITestTextureAtlas;
-  _glyphRenderer?: {
-    value?: ITestGlyphRenderer;
-  };
-}
-
-interface ITestRenderService {
-  _renderer?: {
-    value?: ITestRenderer;
-  };
-}
-
-interface ITestTerminal extends Terminal {
-  _core?: {
-    _renderService?: ITestRenderService;
-  };
-}
-
-interface ITestWebglAddon extends WebglAddon {
-  _renderer?: ITestRenderer;
-}
-
-interface IAtlasEventStats {
-  additions: number;
-  maxPages: number;
-}
-
-interface ITestWindow {
-  WebglAddon: TestWebglAddonConstructor;
-  term: ITestTerminal;
-  addon?: ITestWebglAddon;
-  atlasEventStats?: IAtlasEventStats;
-}
-
-interface IAtlasState {
-  additions: number;
-  atlasTextures: number;
-  maxPages: number;
-}
-
-const REFERENCE_LINE = 'Ref0123456789ABCDEF';
-const REFERENCE_COLS = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19];
-const TERM_SELECTOR = '#terminal-container .xterm-screen';
-
-async function loadWebglStrict(ctx: ITestContext): Promise<void> {
-  await ctx.page.evaluate(() => {
-    const w = window as unknown as ITestWindow;
-    w.addon = new w.WebglAddon({ preserveDrawingBuffer: true });
-    w.term.loadAddon(w.addon);
-  });
-  const isWebglRenderer = await ctx.page.evaluate(() => {
-    const w = window as unknown as ITestWindow;
-    return !!w.addon && w.term._core?._renderService?._renderer?.value === w.addon._renderer;
-  });
-  expect(isWebglRenderer, 'WebGL renderer must be active').toBe(true);
-}
-
-async function installAtlasEventStats(ctx: ITestContext): Promise<void> {
-  const installed = await ctx.page.evaluate(() => {
-    const w = window as unknown as ITestWindow;
-    const atlas = w.term._core?._renderService?._renderer?.value?._charAtlas;
-    if (!atlas || !w.addon) {
-      return false;
-    }
-    const stats: IAtlasEventStats = {
-      additions: 0,
-      maxPages: atlas.pages.length
-    };
-    w.atlasEventStats = stats;
-    w.addon.onAddTextureAtlasCanvas(() => {
-      stats.additions++;
-      stats.maxPages = Math.max(stats.maxPages, atlas.pages.length);
-    });
-    return true;
-  });
-  expect(installed, 'atlas event tracking must be installed').toBe(true);
-}
-
-async function getAtlasState(ctx: ITestContext): Promise<IAtlasState> {
-  const state = await ctx.page.evaluate(() => {
-    const w = window as unknown as ITestWindow;
-    const renderer = w.term._core?._renderService?._renderer?.value;
-    const glyphRenderer = renderer?._glyphRenderer?.value;
-    const stats = w.atlasEventStats;
-    if (!glyphRenderer || !stats) {
-      return undefined;
-    }
-    return {
-      additions: stats.additions,
-      atlasTextures: glyphRenderer._atlasTextures.length,
-      maxPages: stats.maxPages
-    };
-  });
-  expect(state, 'atlas state must be available').toBeDefined();
-  return state!;
-}
-
-async function writeAndWaitForRender(ctx: ITestContext, data: string): Promise<void> {
-  const renderPromise = new Promise<void>(resolve => {
-    const disposable = ctx.proxy.onRender(() => {
-      disposable.dispose();
-      resolve();
-    });
-  });
-  await ctx.proxy.write(data);
-  await renderPromise;
-}
-
-async function refreshAndWaitForRender(ctx: ITestContext): Promise<void> {
-  const renderPromise = new Promise<void>(resolve => {
-    const disposable = ctx.proxy.onRender(() => {
-      disposable.dispose();
-      resolve();
-    });
-  });
-  await ctx.proxy.refresh(0, (await ctx.proxy.rows) - 1);
-  await renderPromise;
-}
-
-function generateSyntheticTuiFrames(frameCount: number, cols: number, rows: number): string[] {
-  const spinner = ['|', '/', '-', '\\'];
-  const words = ['reading', 'rendering', 'atlas', 'terminal', 'buffer', 'tokens', 'diff', 'patch'];
-  const frames: string[] = [];
-  for (let frameIndex = 0; frameIndex < frameCount; frameIndex++) {
-    const lines = [
-      `+${'-'.repeat(cols - 2)}+`,
-      `|${(` ${spinner[frameIndex % spinner.length]} Copilot is working`).padEnd(cols - 2).slice(0, cols - 2)}|`,
-      `+${'-'.repeat(cols - 2)}+`
-    ];
-    for (let row = 3; row < rows - 1; row++) {
-      const foreground = 31 + ((frameIndex + row) % 6);
-      const text = `${words[(frameIndex + row) % words.length]} ${frameIndex}:${row}`;
-      lines.push(`\x1b[${foreground}m${text}\x1b[0m`);
-    }
-    lines.push(`\x1b[2mtokens ${1000 + frameIndex * 37}\x1b[0m`);
-    frames.push(`\x1b[2J\x1b[H${lines.join('\r\n')}`);
-  }
-  return frames;
-}
-
-function generateUniqueGlyphFlood(count: number, cols: number, offset: number): string {
-  const base = 0x4E00;
-  const range = 0x9FFF - base;
-  const perRow = Math.max(1, Math.floor(cols / 2));
-  let result = '';
-  for (let i = 0; i < count; i++) {
-    result += String.fromCodePoint(base + ((offset + i) % range));
-    if ((i + 1) % perRow === 0 && i + 1 < count) {
-      result += '\r\n';
-    }
-  }
-  return result;
-}
-
-async function captureRowSignatures(ctx: ITestContext, row: number, cols: number[], debugName: string): Promise<CellSignature[]> {
-  const screenshotOptions = process.env.DEBUG ? { path: `out-esbuild-test/playwright/${debugName}.png` } : undefined;
-  const buffer = await ctx.page.locator(TERM_SELECTOR).screenshot(screenshotOptions);
-  const frame = {
-    cols: await ctx.proxy.cols,
-    rows: await ctx.proxy.rows,
-    decoded: (await decodePng(new Uint8Array(buffer), { force32: true })).image
-  };
-  return cols.map(col => cellSignature(frame, col, row));
-}
-
-function cellSignature(frame: { cols: number, rows: number, decoded: IImage32 }, col: number, row: number): CellSignature {
-  const grid = 4;
-  const data = frame.decoded.data;
-  const imageWidth = frame.decoded.width;
-  const cellWidth = frame.decoded.width / frame.cols;
-  const cellHeight = frame.decoded.height / frame.rows;
-  const x0 = (col - 1) * cellWidth;
-  const y0 = (row - 1) * cellHeight;
-  const sums = new Array<number>(grid * grid * 4).fill(0);
-  const counts = new Array<number>(grid * grid).fill(0);
-  const startX = Math.max(0, Math.floor(x0));
-  const startY = Math.max(0, Math.floor(y0));
-  const endX = Math.min(frame.decoded.width, Math.ceil(x0 + cellWidth));
-  const endY = Math.min(frame.decoded.height, Math.ceil(y0 + cellHeight));
-
-  for (let y = startY; y < endY; y++) {
-    const gy = Math.min(grid - 1, Math.max(0, Math.floor(((y - y0) / cellHeight) * grid)));
-    for (let x = startX; x < endX; x++) {
-      const gx = Math.min(grid - 1, Math.max(0, Math.floor(((x - x0) / cellWidth) * grid)));
-      const sub = gy * grid + gx;
-      const i = (y * imageWidth + x) * 4;
-      sums[sub * 4] += data[i];
-      sums[sub * 4 + 1] += data[i + 1];
-      sums[sub * 4 + 2] += data[i + 2];
-      sums[sub * 4 + 3] += data[i + 3];
-      counts[sub]++;
-    }
-  }
-
-  const signature = new Array<number>(grid * grid * 4).fill(0);
-  for (let sub = 0; sub < counts.length; sub++) {
-    if (counts[sub] > 0) {
-      signature[sub * 4] = sums[sub * 4] / counts[sub];
-      signature[sub * 4 + 1] = sums[sub * 4 + 1] / counts[sub];
-      signature[sub * 4 + 2] = sums[sub * 4 + 2] / counts[sub];
-      signature[sub * 4 + 3] = sums[sub * 4 + 3] / counts[sub];
-    }
-  }
-  return signature;
-}
-
-function expectSignatureMatches(actual: CellSignature, reference: CellSignature, message: string): void {
-  let diff = 0;
-  for (let i = 0; i < actual.length; i++) {
-    diff = Math.max(diff, Math.abs(actual[i] - reference[i]));
-  }
-  expect(diff, `${message}; max channel diff ${diff}`).toBeLessThanOrEqual(14);
-}
-
-test.describe('WebGL atlas TUI stress (#6038)', () => {
-  test.skip(({ browserName }) => browserName !== 'chromium', 'WebGL atlas tests run on Chromium/SwiftShader only');
-  test.describe.configure({ timeout: 90000 });
-
-  test('primary-buffer glyphs survive alternate-buffer redraws and atlas page churn', async ({ browser }) => {
-    const ctx = await createTestContext(browser);
-    const errors: string[] = [];
-    const onError = (error: Error): void => { errors.push(error.message); };
-    ctx.page.on('pageerror', onError);
-    try {
-      await openTerminal(ctx, { cols: 80, rows: 24, scrollback: 5000 });
-      await loadWebglStrict(ctx);
-      await installAtlasEventStats(ctx);
-
-      await writeAndWaitForRender(ctx, REFERENCE_LINE);
-      const reference = await captureRowSignatures(ctx, 1, REFERENCE_COLS, 'atlas-stress-reference');
-
-      await writeAndWaitForRender(ctx, '\x1b[?1049h');
-      for (const frame of generateSyntheticTuiFrames(30, 80, 24)) {
-        await writeAndWaitForRender(ctx, frame);
-      }
-      const glyphsPerViewport = 23 * 40 - 1;
-      for (let chunk = 0; chunk < 4; chunk++) {
-        await writeAndWaitForRender(ctx, `\x1b[2J\x1b[H${generateUniqueGlyphFlood(glyphsPerViewport, 80, chunk * glyphsPerViewport)}`);
-      }
-      await writeAndWaitForRender(ctx, '\x1b[?1049l');
-      await refreshAndWaitForRender(ctx);
-
-      const state = await getAtlasState(ctx);
-      expect(state.additions, 'stress workload must add atlas pages').toBeGreaterThan(0);
-      expect(state.maxPages, 'stress workload must exercise multiple atlas pages').toBeGreaterThan(1);
-      expect(state.maxPages, 'atlas pages must remain within renderer texture capacity').toBeLessThanOrEqual(state.atlasTextures);
-      expect(errors, `renderer must not throw during TUI stress: ${errors[0] ?? ''}`).toEqual([]);
-
-      const primaryText = await ctx.page.evaluate(() => {
-        const w = window as unknown as ITestWindow;
-        return w.term.buffer.active.getLine(0)?.translateToString(true);
-      });
-      expect(primaryText, 'primary buffer must still contain the reference line').toBe(REFERENCE_LINE);
-
-      const after = await captureRowSignatures(ctx, 1, REFERENCE_COLS, 'atlas-stress-after');
-      for (let i = 0; i < REFERENCE_COLS.length; i++) {
-        expectSignatureMatches(after[i], reference[i], `primary-buffer glyph at col ${REFERENCE_COLS[i]} changed after TUI stress`);
-      }
-    } finally {
-      ctx.page.off('pageerror', onError);
-      await ctx.page.close();
-    }
-  });
-});

addons/addon-webgl/test/WebglCustomGlyphs.test.ts

@@ -1,77 +0,0 @@
-/**
- * Copyright (c) 2026 The xterm.js authors. All rights reserved.
- * @license MIT
- */
-
-import test, { expect } from '@playwright/test';
-import { platform } from 'os';
-import { ITestContext, createTestContext, openTerminal } from '../../../test/playwright/TestUtils';
-
-interface ITestRendererWithAtlasCanvas {
-  readonly _charAtlas?: {
-    readonly _tmpCanvas?: HTMLCanvasElement;
-  };
-}
-
-async function writeAndWaitForRender(ctx: ITestContext, data: string): Promise<void> {
-  const renderPromise = new Promise<void>(resolve => {
-    const disposable = ctx.proxy.onRender(() => {
-      disposable.dispose();
-      resolve();
-    });
-  });
-  await ctx.proxy.write(data);
-  await renderPromise;
-}
-
-test.describe('WebGL custom glyphs', () => {
-  if (platform() === 'linux') {
-    test.skip(({ browserName }) => browserName === 'firefox' || browserName === 'webkit');
-  }
-
-  test('pattern glyphs render after the terminal is adopted into another document', async ({ browser }) => {
-    const ctx = await createTestContext(browser);
-    const errors: string[] = [];
-    const onError = (error: Error): void => { errors.push(error.message); };
-    ctx.page.on('pageerror', onError);
-    try {
-      await openTerminal(ctx);
-      await ctx.page.evaluate(`
-        window.addon = new window.WebglAddon({ customGlyphs: true });
-        window.term.loadAddon(window.addon);
-      `);
-      await ctx.page.evaluate(() => {
-        const frame = document.createElement('iframe');
-        document.body.appendChild(frame);
-        const auxiliaryDocument = frame.contentDocument;
-        if (!auxiliaryDocument?.body || !window.term.element) {
-          throw new Error('Auxiliary document and terminal element must be available');
-        }
-        const renderer = window.term._core?._renderService?._renderer?.value as ITestRendererWithAtlasCanvas | undefined;
-        const atlasCanvas = renderer?._charAtlas?._tmpCanvas;
-        if (!atlasCanvas) {
-          throw new Error('Texture atlas canvas must be available');
-        }
-        // Model the atlas state after an uncached glyph has attached the measurement canvas.
-        window.term.element.appendChild(atlasCanvas);
-        auxiliaryDocument.body.appendChild(window.term.element);
-        if (atlasCanvas.ownerDocument !== auxiliaryDocument) {
-          throw new Error('Texture atlas canvas must be adopted into the auxiliary document');
-        }
-        auxiliaryDocument.createElement = () => {
-          throw new Error('Not allowed to create elements in the auxiliary document');
-        };
-      });
-
-      await writeAndWaitForRender(ctx, '\u2591');
-      await writeAndWaitForRender(ctx, 'X');
-
-      const line = await ctx.page.evaluate(() => window.term.buffer.active.getLine(0)?.translateToString(true));
-      expect(errors, `renderer must not create pattern canvases in the auxiliary document: ${errors[0] ?? ''}`).toEqual([]);
-      expect(line).toBe('\u2591X');
-    } finally {
-      ctx.page.off('pageerror', onError);
-      await ctx.page.close();
-    }
-  });
-});

addons/addon-webgl/test/WebglSharedAtlasGarble.test.ts

@@ -1,282 +0,0 @@
-/**
- * Copyright (c) 2025 The xterm.js authors. All rights reserved.
- * @license MIT
- */
-
-import { IImage32, decodePng } from '@lunapaint/png-codec';
-import test, { expect } from '@playwright/test';
-import type { Terminal, ITerminalInitOnlyOptions, ITerminalOptions } from '@xterm/xterm';
-import type { IWebglAddonOptions, WebglAddon } from '@xterm/addon-webgl';
-import { ITestContext, createTestContext, openTerminal } from '../../../test/playwright/TestUtils';
-
-type CellSignature = number[];
-type TestTerminalConstructor = new (options?: ITerminalOptions & ITerminalInitOnlyOptions) => ITestTerminal;
-type TestWebglAddonConstructor = new (options?: IWebglAddonOptions) => ITestWebglAddon;
-
-interface ITestTextureAtlasConstructor {
-  maxAtlasPages: number | undefined;
-}
-
-interface ITestTextureAtlas {
-  constructor: ITestTextureAtlasConstructor;
-}
-
-interface ITestRenderer {
-  _charAtlas?: ITestTextureAtlas;
-}
-
-interface ITestRenderService {
-  _renderer?: {
-    value?: ITestRenderer;
-  };
-}
-
-interface ITestTerminal extends Terminal {
-  _core?: {
-    _renderService?: ITestRenderService;
-  };
-}
-
-interface ITestWebglAddon extends WebglAddon {
-  _renderer?: ITestRenderer;
-}
-
-declare global {
-  interface Window { // eslint-disable-line @typescript-eslint/naming-convention
-    Terminal: TestTerminalConstructor;
-    WebglAddon: TestWebglAddonConstructor;
-    term: ITestTerminal;
-    termB?: ITestTerminal;
-    addon?: ITestWebglAddon;
-    addonB?: ITestWebglAddon;
-  }
-}
-
-const HEADER = ' HEADER_REF_0123456789';
-const HEADER_COLS = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
-const TERM_B_SELECTOR = '#terminal-container-b .xterm-screen';
-
-async function loadWebglStrict(ctx: ITestContext): Promise<void> {
-  await ctx.page.evaluate(() => {
-    window.addon = new window.WebglAddon({ preserveDrawingBuffer: true });
-    window.term.loadAddon(window.addon);
-  });
-  const isWebglRenderer = await ctx.page.evaluate(() => {
-    return !!window.addon && window.term?._core?._renderService?._renderer?.value === window.addon._renderer;
-  });
-  expect(isWebglRenderer, 'WebGL renderer must be active').toBe(true);
-}
-
-async function createTerminalB(ctx: ITestContext): Promise<void> {
-  await ctx.page.evaluate(() => {
-    window.termB?.dispose();
-    document.getElementById('terminal-container-b')?.remove();
-    const el = document.createElement('div');
-    el.id = 'terminal-container-b';
-    document.body.appendChild(el);
-    window.termB = new window.Terminal({ cols: 80, rows: 24, allowProposedApi: true });
-    window.termB.open(el);
-    window.addonB = new window.WebglAddon({ preserveDrawingBuffer: true });
-    window.termB.loadAddon(window.addonB);
-  });
-}
-
-async function writeToBAndWaitForRender(ctx: ITestContext, data: string): Promise<void> {
-  await ctx.page.evaluate(d => new Promise<void>(resolve => {
-    const termB = window.termB;
-    if (!termB) {
-      throw new Error('Terminal B must be created before writing to it');
-    }
-    const disposable = termB.onRender(() => {
-      disposable.dispose();
-      resolve();
-    });
-    termB.write(d);
-  }), data);
-}
-
-async function writeAndWaitForRender(ctx: ITestContext, data: string): Promise<void> {
-  const renderPromise = new Promise<void>(resolve => {
-    const disposable = ctx.proxy.onRender(() => {
-      disposable.dispose();
-      resolve();
-    });
-  });
-  await ctx.proxy.write(data);
-  await renderPromise;
-}
-
-async function setMaxAtlasPages(ctx: ITestContext, maxAtlasPages: number): Promise<void> {
-  const applied = await ctx.page.evaluate(max => {
-    const atlas = window.term?._core?._renderService?._renderer?.value?._charAtlas;
-    if (!atlas) {
-      return false;
-    }
-    atlas.constructor.maxAtlasPages = max;
-    return true;
-  }, maxAtlasPages);
-  expect(applied, 'should be able to set TextureAtlas.maxAtlasPages').toBe(true);
-}
-
-async function resetMaxAtlasPages(ctx: ITestContext): Promise<void> {
-  await ctx.page.evaluate(() => {
-    const atlas = window.term?._core?._renderService?._renderer?.value?._charAtlas;
-    if (atlas) {
-      atlas.constructor.maxAtlasPages = undefined;
-    }
-  });
-}
-
-function generateColoredAsciiFlood(cells: number, offset: number = 0): string {
-  const letters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
-  let out = '';
-  for (let i = 0; i < cells; i++) {
-    const ch = letters[(offset + i) % letters.length];
-    const fg = (offset + i) % 256;
-    const bg = (offset + i * 7) % 256;
-    out += `\x1b[38;5;${fg}m\x1b[48;5;${bg}m${ch}`;
-    if ((i + 1) % 78 === 0 && i + 1 < cells) {
-      out += '\x1b[0m\r\n';
-    }
-  }
-  return out + '\x1b[0m';
-}
-
-async function captureRowSignatures(ctx: ITestContext, row: number, cols: number[]): Promise<CellSignature[]> {
-  const screenshotOptions = process.env.DEBUG ? { path: 'out-esbuild-test/playwright/shared-atlas-term-b.png' } : undefined;
-  const buffer = await ctx.page.locator(TERM_B_SELECTOR).screenshot(screenshotOptions);
-  const frame = {
-    cols: 80,
-    rows: 24,
-    decoded: (await decodePng(new Uint8Array(buffer), { force32: true })).image
-  };
-  return cols.map(col => cellSignature(frame, col, row));
-}
-
-function cellSignature(frame: { cols: number, rows: number, decoded: IImage32 }, col: number, row: number): CellSignature {
-  const grid = 4;
-  const data = frame.decoded.data;
-  const imageWidth = frame.decoded.width;
-  const cellWidth = frame.decoded.width / frame.cols;
-  const cellHeight = frame.decoded.height / frame.rows;
-  const x0 = (col - 1) * cellWidth;
-  const y0 = (row - 1) * cellHeight;
-  const sums = new Array<number>(grid * grid * 4).fill(0);
-  const counts = new Array<number>(grid * grid).fill(0);
-  const startX = Math.max(0, Math.floor(x0));
-  const startY = Math.max(0, Math.floor(y0));
-  const endX = Math.min(frame.decoded.width, Math.ceil(x0 + cellWidth));
-  const endY = Math.min(frame.decoded.height, Math.ceil(y0 + cellHeight));
-
-  for (let y = startY; y < endY; y++) {
-    const gy = Math.min(grid - 1, Math.max(0, Math.floor(((y - y0) / cellHeight) * grid)));
-    for (let x = startX; x < endX; x++) {
-      const gx = Math.min(grid - 1, Math.max(0, Math.floor(((x - x0) / cellWidth) * grid)));
-      const sub = gy * grid + gx;
-      const i = (y * imageWidth + x) * 4;
-      sums[sub * 4] += data[i];
-      sums[sub * 4 + 1] += data[i + 1];
-      sums[sub * 4 + 2] += data[i + 2];
-      sums[sub * 4 + 3] += data[i + 3];
-      counts[sub]++;
-    }
-  }
-
-  const signature = new Array<number>(grid * grid * 4).fill(0);
-  for (let sub = 0; sub < counts.length; sub++) {
-    if (counts[sub] > 0) {
-      signature[sub * 4] = sums[sub * 4] / counts[sub];
-      signature[sub * 4 + 1] = sums[sub * 4 + 1] / counts[sub];
-      signature[sub * 4 + 2] = sums[sub * 4 + 2] / counts[sub];
-      signature[sub * 4 + 3] = sums[sub * 4 + 3] / counts[sub];
-    }
-  }
-  return signature;
-}
-
-function expectSignatureMatches(actual: CellSignature, reference: CellSignature, message: string): void {
-  let diff = 0;
-  for (let i = 0; i < actual.length; i++) {
-    diff = Math.max(diff, Math.abs(actual[i] - reference[i]));
-  }
-  expect(diff, `${message}; max channel diff ${diff}`).toBeLessThanOrEqual(14);
-}
-
-test.describe('shared-atlas garble across terminals (#6038)', () => {
-  test.skip(({ browserName }) => browserName !== 'chromium');
-  test.describe.configure({ timeout: 60000 });
-
-  test('keeps a second terminal rendering correctly after shared atlas page merges', async ({ browser }) => {
-    const ctx = await createTestContext(browser);
-    try {
-      await openTerminal(ctx, { cols: 80, rows: 24 });
-      await loadWebglStrict(ctx);
-      await createTerminalB(ctx);
-
-      const atlasShared = await ctx.page.evaluate(() => {
-        return window.term._core?._renderService?._renderer?.value?._charAtlas === window.termB?._core?._renderService?._renderer?.value?._charAtlas;
-      });
-      expect(atlasShared, 'terminals with equal configs should share one texture atlas').toBe(true);
-
-      await setMaxAtlasPages(ctx, 4);
-
-      await writeToBAndWaitForRender(ctx, HEADER);
-      const reference = await captureRowSignatures(ctx, 1, HEADER_COLS);
-
-      for (let c = 0; c < 10; c++) {
-        await writeAndWaitForRender(ctx, '\x1b[2;1H' + generateColoredAsciiFlood(23 * 78, c * 23 * 78));
-      }
-
-      await writeToBAndWaitForRender(ctx, '\x1b[24;1Hx');
-      const termBHeader = await ctx.page.evaluate(() => window.termB?.buffer.active.getLine(0)?.translateToString(true));
-      expect(termBHeader, 'terminal B buffer must still contain the header').toBe(HEADER);
-
-      const after = await captureRowSignatures(ctx, 1, HEADER_COLS);
-      for (let i = 0; i < HEADER_COLS.length; i++) {
-        expectSignatureMatches(after[i], reference[i], `terminal B header col ${HEADER_COLS[i]} garbled by terminal A's atlas merges`);
-      }
-    } finally {
-      await resetMaxAtlasPages(ctx).catch(() => {});
-      await ctx.page.close();
-    }
-  });
-
-  test('keeps a second terminal rendering correctly after terminal A clears the shared atlas', async ({ browser }) => {
-    const ctx = await createTestContext(browser);
-    try {
-      await openTerminal(ctx, { cols: 80, rows: 24 });
-      await loadWebglStrict(ctx);
-      await createTerminalB(ctx);
-
-      const atlasShared = await ctx.page.evaluate(() => {
-        return window.term._core?._renderService?._renderer?.value?._charAtlas === window.termB?._core?._renderService?._renderer?.value?._charAtlas;
-      });
-      expect(atlasShared, 'terminals with equal configs should share one texture atlas').toBe(true);
-
-      await writeToBAndWaitForRender(ctx, HEADER);
-      const reference = await captureRowSignatures(ctx, 1, HEADER_COLS);
-
-      // Terminal A alone clears the shared atlas, as embedders do to force a redraw (VS Code calls
-      // this for every terminal on OS resume). This wipes the pages that terminal B's model still
-      // holds texture coords into.
-      await ctx.proxy.clearTextureAtlas();
-
-      // Terminal A repopulates the cleared pages with a different glyph set, so B's stale coords now
-      // resolve to whatever A rasterized into those slots.
-      await writeAndWaitForRender(ctx, '\x1b[2;1H' + generateColoredAsciiFlood(23 * 78));
-
-      // Nudge B into a render that does not touch row 1, mirroring a terminal that is idle but
-      // visible. Row 1 must still be drawn from a model B rebuilt against the current atlas.
-      await writeToBAndWaitForRender(ctx, '\x1b[24;1Hx');
-      const termBHeader = await ctx.page.evaluate(() => window.termB?.buffer.active.getLine(0)?.translateToString(true));
-      expect(termBHeader, 'terminal B buffer must still contain the header').toBe(HEADER);
-
-      const after = await captureRowSignatures(ctx, 1, HEADER_COLS);
-      for (let i = 0; i < HEADER_COLS.length; i++) {
-        expectSignatureMatches(after[i], reference[i], `terminal B header col ${HEADER_COLS[i]} garbled by terminal A's atlas clear`);
-      }
-    } finally {
-      await ctx.page.close();
-    }
-  });
-});

demo/client/components/window/addonImageWindow.ts

@@ -67,8 +67,6 @@ export class AddonImageWindow extends BaseWindow implements IControlWindow {
     dlIip.appendChild(dtIip);
     this._addDdWithButton(dlIip, 'image-demo3', 'palette (png File)');
     this._addDdWithButton(dlIip, 'image-demo4', 'dice (qoi MultipartFile)');
-    this._addDdWithButton(dlIip, 'image-demo5', 'rose (webp File)');
-    this._addDdWithButton(dlIip, 'image-demo6', 'kimono (avif MultipartFile)');
     container.appendChild(dlIip);
 
     // Kitty demos
@@ -175,15 +173,11 @@ export class AddonImageWindow extends BaseWindow implements IControlWindow {
     document.getElementById('image-demo2')!.addEventListener('click',
       sixelDemo('https://raw.githubusercontent.com/jerch/node-sixel/master/testfiles/test2.sixel'));
     document.getElementById('image-demo3')!.addEventListener('click',
-      iipDemo('https://raw.githubusercontent.com/xtermjs/xterm.js/master/addons/addon-image/fixture/palette.png'));
+      iipDemo('https://raw.githubusercontent.com/jerch/node-sixel/master/palette.png'));
     document.getElementById('image-demo4')!.addEventListener('click',
-      iipDemoMulti('https://raw.githubusercontent.com/xtermjs/xterm.js/master/addons/addon-image/fixture/testimages/dice.qoi'));
-    document.getElementById('image-demo5')!.addEventListener('click',
-      iipDemo('https://raw.githubusercontent.com/xtermjs/xterm.js/master/addons/addon-image/fixture/testimages/1_webp_a.webp'));
-    document.getElementById('image-demo6')!.addEventListener('click',
-      iipDemoMulti('https://raw.githubusercontent.com/xtermjs/xterm.js/master/addons/addon-image/fixture/testimages/kimono.crop.avif'));
+      iipDemoMulti('https://raw.githubusercontent.com/jerch/xterm-wasm-parts/master/fixtures/qoi/dice.qoi'));
     document.getElementById('image-demo-kitty1')!.addEventListener('click',
-      kittyDemo('https://raw.githubusercontent.com/xtermjs/xterm.js/master/addons/addon-image/fixture/palette.png'));
+      kittyDemo('https://raw.githubusercontent.com/jerch/node-sixel/master/palette.png'));
 
     // demo for image retrieval API
     this._terminal.element!.addEventListener('click', (ev: MouseEvent) => {

demo/client/components/window/webglWindow.ts

@@ -12,33 +12,31 @@ export class WebglWindow extends BaseWindow implements IControlWindow {
 
   private _textureAtlasContainer!: HTMLElement;
   private _stressRunning = false;
-  private _scrollOutput: HTMLInputElement | undefined;
+  private _stressScrolling: HTMLInputElement | undefined;
 
   public build(container: HTMLElement): void {
-    const stressButtons = document.createElement('div');
+    const stressDiv = document.createElement('div');
     const stressStart = document.createElement('button');
     stressStart.id = 'stress-start';
     stressStart.textContent = 'atlas stress start';
     stressStart.addEventListener('click', () => this._stress());
-    stressButtons.appendChild(stressStart);
+    stressDiv.appendChild(stressStart);
 
     const stressStop = document.createElement('button');
     stressStop.id = 'stress-stop';
     stressStop.textContent = 'atlas stress stop';
     stressStop.addEventListener('click', () => this._stressRunning = false);
-    stressButtons.appendChild(stressStop);
-    container.appendChild(stressButtons);
+    stressDiv.appendChild(stressStop);
 
-    const stressOptions = document.createElement('div');
-    this._scrollOutput = document.createElement('input');
-    this._scrollOutput.type = 'checkbox';
-    this._scrollOutput.id = 'scroll-output';
-    stressOptions.appendChild(this._scrollOutput);
-    const scrollOutputLabel = document.createElement('label');
-    scrollOutputLabel.htmlFor = 'scroll-output';
-    scrollOutputLabel.textContent = 'Scroll output';
-    stressOptions.appendChild(scrollOutputLabel);
-    container.appendChild(stressOptions);
+    this._stressScrolling = document.createElement('input');
+    this._stressScrolling.type = 'checkbox';
+    this._stressScrolling.id = 'stress-scrolling';
+    stressDiv.appendChild(this._stressScrolling);
+    const stressScrollingLabel = document.createElement('label');
+    stressScrollingLabel.htmlFor = 'stress-scrolling';
+    stressScrollingLabel.textContent = 'stress scrolling';
+    stressDiv.appendChild(stressScrollingLabel);
+    container.appendChild(stressDiv);
 
     const zoomCheckbox = document.createElement('input');
     zoomCheckbox.type = 'checkbox';
@@ -82,7 +80,7 @@ export class WebglWindow extends BaseWindow implements IControlWindow {
       return;
     }
     this._stressRunning = true;
-    const scrollOutput = !!(this._scrollOutput?.checked);
+    const scrolling = !!(this._stressScrolling?.checked);
     for (let r = 0; r < 256; r += 2) {
       for (let g = 0; g < 256; g += 2) {
         let s: string[] = [];
@@ -93,7 +91,7 @@ export class WebglWindow extends BaseWindow implements IControlWindow {
           const rbg = `RGB: ${[r, g, b]}`;
           s.push(`\r\x1b[38;2;${r};${g};${b}m${rbg.padEnd(18, ' ')}${TEXT}`);
           if (s.length >= 16) {
-            if (scrollOutput) {
+            if (scrolling) {
               await new Promise<void>(r => this._terminal.write(s.join('\r\n') + '\r\n', r));
             } else {
               await new Promise<void>(r => this._terminal.write('\x1b[H' + s.join('\r\n'), r));

package-lock.json

@@ -663,9 +663,9 @@
       }
     },
     "node_modules/@esbuild/aix-ppc64": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/aix-ppc64/-/aix-ppc64-0.28.1.tgz",
-      "integrity": "sha512-Svl7tq8k/08+p6CXPpRjQ1fKX+1odH/BQbb48fV6fj3CWHhsoIOoY87w1oHXm0qEpkIK3ZfVgp0hed3XBXzXMQ==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/@esbuild/aix-ppc64/-/aix-ppc64-0.28.0.tgz",
+      "integrity": "sha512-lhRUCeuOyJQURhTxl4WkpFTjIsbDayJHih5kZC1giwE+MhIzAb7mEsQMqMf18rHLsrb5qI1tafG20mLxEWcWlA==",
       "cpu": [
         "ppc64"
       ],
@@ -680,9 +680,9 @@
       }
     },
     "node_modules/@esbuild/android-arm": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/android-arm/-/android-arm-0.28.1.tgz",
-      "integrity": "sha512-0k2F129Xdio1TdJfzJ8sy1Q47vUD2NnwdhiAf7drUN1EBTfPf4hsFCtmMgu/6m8JSzsBrlmVjudMBQqOfG8usQ==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/@esbuild/android-arm/-/android-arm-0.28.0.tgz",
+      "integrity": "sha512-wqh0ByljabXLKHeWXYLqoJ5jKC4XBaw6Hk08OfMrCRd2nP2ZQ5eleDZC41XHyCNgktBGYMbqnrJKq/K/lzPMSQ==",
       "cpu": [
         "arm"
       ],
@@ -697,9 +697,9 @@
       }
     },
     "node_modules/@esbuild/android-arm64": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/android-arm64/-/android-arm64-0.28.1.tgz",
-      "integrity": "sha512-34EGEbCIAgosYz6goLcopX6Mo7NyGv9tfwEM2/7Ce2VcVRk568iSvniGWcUXIy7wEDR1wzolcxcriFVrWYcwBg==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/@esbuild/android-arm64/-/android-arm64-0.28.0.tgz",
+      "integrity": "sha512-+WzIXQOSaGs33tLEgYPYe/yQHf0WTU0X42Jca3y8NWMbUVhp7rUnw+vAsRC/QiDrdD31IszMrZy+qwPOPjd+rw==",
       "cpu": [
         "arm64"
       ],
@@ -714,9 +714,9 @@
       }
     },
     "node_modules/@esbuild/android-x64": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/android-x64/-/android-x64-0.28.1.tgz",
-      "integrity": "sha512-dbwY7ltSMDWsRatcRpCnES4F+im88OCUgGZjy52shC7GqHRE/cYlxNbB4Z4UpJswpcc4Qxd2oE/ufM0p61IKng==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/@esbuild/android-x64/-/android-x64-0.28.0.tgz",
+      "integrity": "sha512-+VJggoaKhk2VNNqVL7f6S189UzShHC/mR9EE8rDdSkdpN0KflSwWY/gWjDrNxxisg8Fp1ZCD9jLMo4m0OUfeUA==",
       "cpu": [
         "x64"
       ],
@@ -731,9 +731,9 @@
       }
     },
     "node_modules/@esbuild/darwin-arm64": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/darwin-arm64/-/darwin-arm64-0.28.1.tgz",
-      "integrity": "sha512-TZbWkQY7kvTAXbXUT7uVACR5cMHsDiSz9z7ZKAX/RTq/WJEk3QyRr0wZpNhBDX+/0CtdqUIJlOiodQcta6tY3Q==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/@esbuild/darwin-arm64/-/darwin-arm64-0.28.0.tgz",
+      "integrity": "sha512-0T+A9WZm+bZ84nZBtk1ckYsOvyA3x7e2Acj1KdVfV4/2tdG4fzUp91YHx+GArWLtwqp77pBXVCPn2We7Letr0Q==",
       "cpu": [
         "arm64"
       ],
@@ -748,9 +748,9 @@
       }
     },
     "node_modules/@esbuild/darwin-x64": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/darwin-x64/-/darwin-x64-0.28.1.tgz",
-      "integrity": "sha512-zfdzgK9ACBNZLI/CyHTOx81SyNbM6YXn7rxSgX97VjyiPl9W1i4Ka4fgKECEoFCKGpvBj5qArWIGgQjOwkgskQ==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/@esbuild/darwin-x64/-/darwin-x64-0.28.0.tgz",
+      "integrity": "sha512-fyzLm/DLDl/84OCfp2f/XQ4flmORsjU7VKt8HLjvIXChJoFFOIL6pLJPH4Yhd1n1gGFF9mPwtlN5Wf82DZs+LQ==",
       "cpu": [
         "x64"
       ],
@@ -765,9 +765,9 @@
       }
     },
     "node_modules/@esbuild/freebsd-arm64": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/freebsd-arm64/-/freebsd-arm64-0.28.1.tgz",
-      "integrity": "sha512-wG2EA8ENdEI0qhkSZMjfqrdY+ziCYCPMmtZjjIwOmXFjmyzEHn+UUxk5of+SYsjtfs3VpnlC7QLzSI5hY/rOAw==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/@esbuild/freebsd-arm64/-/freebsd-arm64-0.28.0.tgz",
+      "integrity": "sha512-l9GeW5UZBT9k9brBYI+0WDffcRxgHQD8ShN2Ur4xWq/NFzUKm3k5lsH4PdaRgb2w7mI9u61nr2gI2mLI27Nh3Q==",
       "cpu": [
         "arm64"
       ],
@@ -782,9 +782,9 @@
       }
     },
     "node_modules/@esbuild/freebsd-x64": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/freebsd-x64/-/freebsd-x64-0.28.1.tgz",
-      "integrity": "sha512-i7dZ9vQgnvSCzi/rYCXNgtF/U+eKZNJBzu3eTQbRgHnM7tNSizLOkRFAl3qzVc/Op/u5YkHHa4pf/3DOYHthLQ==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/@esbuild/freebsd-x64/-/freebsd-x64-0.28.0.tgz",
+      "integrity": "sha512-BXoQai/A0wPO6Es3yFJ7APCiKGc1tdAEOgeTNy3SsB491S3aHn4S4r3e976eUnPdU+NbdtmBuLncYir2tMU9Nw==",
       "cpu": [
         "x64"
       ],
@@ -799,9 +799,9 @@
       }
     },
     "node_modules/@esbuild/linux-arm": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/linux-arm/-/linux-arm-0.28.1.tgz",
-      "integrity": "sha512-qVXBOHQS+d5Y722GwJzJUtOLlX7km3CraOaGormF1pDtPd2C/l1SHRPgjLunLGe51Sh5YYWKMFDyV4SxgMQYTQ==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/@esbuild/linux-arm/-/linux-arm-0.28.0.tgz",
+      "integrity": "sha512-CjaaREJagqJp7iTaNQjjidaNbCKYcd4IDkzbwwxtSvjI7NZm79qiHc8HqciMddQ6CKvJT6aBd8lO9kN/ZudLlw==",
       "cpu": [
         "arm"
       ],
@@ -816,9 +816,9 @@
       }
     },
     "node_modules/@esbuild/linux-arm64": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/linux-arm64/-/linux-arm64-0.28.1.tgz",
-      "integrity": "sha512-yHs+0uc8+nvEAfAfxrWQKK5peSNzBc4PegcMO0EJ2hT71uA7vB8Ihg2e77R2P7SG5uYjPbHlLLmve4LLLRCf0g==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/@esbuild/linux-arm64/-/linux-arm64-0.28.0.tgz",
+      "integrity": "sha512-RVyzfb3FWsGA55n6WY0MEIEPURL1FcbhFE6BffZEMEekfCzCIMtB5yyDcFnVbTnwk+CLAgTujmV/Lgvih56W+A==",
       "cpu": [
         "arm64"
       ],
@@ -833,9 +833,9 @@
       }
     },
     "node_modules/@esbuild/linux-ia32": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/linux-ia32/-/linux-ia32-0.28.1.tgz",
-      "integrity": "sha512-d1z4ZuP0ajrfz/FhGT4vv278rX8KnPPJx8i5+AtK7TYbx9Le9F1hyzurZpkEyjkGa9dUGhQow4C1NmeGvqxN2w==",
+      "version": "0.28.0",
+      "resolved": "https://registry.npmjs.org/@esbuild/linux-ia32/-/linux-ia32-0.28.0.tgz",
+      "integrity": "sha512-KBnSTt1kxl9x70q+ydterVdl+Cn0H18ngRMRCEQfrbqdUuntQQ0LoMZv47uB97NljZFzY6HcfqEZ2SAyIUTQBQ==",
       "cpu": [
         "ia32"
       ],
@@ -850,9 +850,9 @@
       }
     },
     "node_modules/@esbuild/linux-loong64": {
-      "version": "0.28.1",
-      "resolved": "https://registry.npmjs.org/@esbuild/linux-loong64/-/linux-loong64-0.28.1.tgz",
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-      "version": "2.1.4",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-2.1.4.tgz",
-      "integrity": "sha512-hGfVzPxthbf3+2yjg/RBs60cB0FhqBS/zvdV/4wn4/BmN0bNMMHPc4V/BbFieqf1TKAGGAHnY4eSjajCl0f2Xg==",
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-2.1.0.tgz",
+      "integrity": "sha512-TN1kCZAgdgweJhWWpgKYrQaMNHcDULHkWwQIspdtjV4Y5aurRdZpjAqn6yX3FPqTA9ngHCc4hJxMAMgGfve85w==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -7127,9 +7127,9 @@
       }
     },
     "node_modules/shell-quote": {
-      "version": "1.9.0",
-      "resolved": "https://registry.npmjs.org/shell-quote/-/shell-quote-1.9.0.tgz",
-      "integrity": "sha512-Iov+JwFv/2HcTpcwNMKd8+IWNb8tboQJNQTkAY/LLVK7gGH9jy+LGkVqPxfekHl+yMmiqXszdGWXgkfml7hjqA==",
+      "version": "1.8.3",
+      "resolved": "https://registry.npmjs.org/shell-quote/-/shell-quote-1.8.3.tgz",
+      "integrity": "sha512-ObmnIF4hXNg1BqhnHmgbDETF8dLPCggZWBjkQfhZpbszZnYur5DUljTcCHii5LC3J5E0yeO/1LIMyH+UvHQgyw==",
       "dev": true,
       "license": "MIT",
       "engines": {
@@ -7975,9 +7975,9 @@
       }
     },
     "node_modules/undici": {
-      "version": "7.29.0",
-      "resolved": "https://registry.npmjs.org/undici/-/undici-7.29.0.tgz",
-      "integrity": "sha512-IDxfleLmmbSskfWSUATiN1nfn2rDuvnMOqb5CWR92iIfojA0Ud+ulOAAEQ57LPr9rWmsreUyf5lwyao+7GNNVw==",
+      "version": "7.25.0",
+      "resolved": "https://registry.npmjs.org/undici/-/undici-7.25.0.tgz",
+      "integrity": "sha512-xXnp4kTyor2Zq+J1FfPI6Eq3ew5h6Vl0F/8d9XU5zZQf1tX9s2Su1/3PiMmUANFULpmksxkClamIZcaUqryHsQ==",
       "dev": true,
       "license": "MIT",
       "engines": {
@@ -8452,9 +8452,9 @@
       "license": "ISC"
     },
     "node_modules/ws": {
-      "version": "8.21.3",
-      "resolved": "https://registry.npmjs.org/ws/-/ws-8.21.3.tgz",
-      "integrity": "sha512-201TZ/kPWxoPr/OKWjquZR1SWKXcvxdH+e1xrx89b3YbmzLMFCLfnaG1HFIgWzJOEWZ7MvpK++odZufgYR50Rw==",
+      "version": "8.20.1",
+      "resolved": "https://registry.npmjs.org/ws/-/ws-8.20.1.tgz",
+      "integrity": "sha512-It4dO0K5v//JtTXuPkfEOaI3uUN87iYPnqo/ZzqCoG3g8uhA66QUMs/SrM0YK7/NAu+r4LMh/9dq2A7k+rHs+w==",
       "dev": true,
       "license": "MIT",
       "engines": {

src/browser/CoreBrowserTerminal.ts

@@ -492,7 +492,6 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
       // https://issuetracker.google.com/issues/260170397
       this.textarea.setAttribute('aria-multiline', 'false');
     }
-    this.textarea.setAttribute('autocomplete', 'off');
     this.textarea.setAttribute('autocorrect', 'off');
     this.textarea.setAttribute('autocapitalize', 'off');
     this.textarea.setAttribute('spellcheck', 'false');

src/browser/renderer/dom/DomRendererRowFactory.test.ts

@@ -6,14 +6,16 @@
 import jsdom = require('jsdom');
 import { assert } from 'chai';
 import { DomRendererRowFactory } from './DomRendererRowFactory';
-import { DEFAULT_ATTR, FgFlags, BgFlags, Attributes, UnderlineStyle } from '../../../common/buffer/Constants';
+import { NULL_CELL_CODE, NULL_CELL_WIDTH, NULL_CELL_CHAR, DEFAULT_ATTR, FgFlags, BgFlags, Attributes, UnderlineStyle } from '../../../common/buffer/Constants';
 import { BufferLine, DEFAULT_ATTR_DATA } from '../../../common/buffer/BufferLine';
+import { BufferLineStringCache } from '../../../common/buffer/BufferLineStringCache';
 import { IBufferLine } from '../../../common/buffer/Types';
 import { CellData } from '../../../common/buffer/CellData';
 import { MockCoreService, MockDecorationService, MockOptionsService, createCellData, NULL_CELL_DATA } from '../../../common/TestUtils.test';
 import { MockCharacterJoinerService, MockCoreBrowserService, MockThemeService } from '../../TestUtils.test';
 import { TestWidthCache } from './WidthCache.test';
 
+const TEST_STRING_CACHE = new BufferLineStringCache();
 
 describe('DomRendererRowFactory', () => {
   let dom: jsdom.JSDOM;
@@ -515,7 +517,7 @@ describe('DomRendererRowFactory', () => {
   }
 
   function createEmptyLineData(cols: number): IBufferLine {
-    const lineData = new BufferLine(cols);
+    const lineData = new BufferLine(TEST_STRING_CACHE, cols);
     for (let i = 0; i < cols; i++) {
       lineData.setCell(i, NULL_CELL_DATA);
     }

src/browser/services/CharacterJoinerService.test.ts

@@ -7,10 +7,12 @@ import { assert } from 'chai';
 import { ICharacterJoinerService } from './Services';
 import { CharacterJoinerService } from './CharacterJoinerService';
 import { BufferLine } from '../../common/buffer/BufferLine';
+import { BufferLineStringCache } from '../../common/buffer/BufferLineStringCache';
 import { IBufferLine } from '../../common/buffer/Types';
 import { CellData } from '../../common/buffer/CellData';
 import { MockBufferService, createCellData } from '../../common/TestUtils.test';
 
+const TEST_STRING_CACHE = new BufferLineStringCache();
 
 describe('CharacterJoinerService', () => {
   let service: ICharacterJoinerService;
@@ -23,7 +25,7 @@ describe('CharacterJoinerService', () => {
     lines.set(2, lineData([['a -> b -', 0xFFFFFFFF], ['> c -> d', 0]]));
 
     lines.set(3, lineData([['no joined ranges']]));
-    lines.set(4, new BufferLine(0));
+    lines.set(4, new BufferLine(TEST_STRING_CACHE, 0));
     lines.set(5, lineData([['a', 0x11111111], [' -> b -> c -> '], ['d', 0x22222222]]));
     const line6 = lineData([['wi']]);
     line6.resize(line6.length + 1, createCellData(0, '￥', 2));
@@ -268,7 +270,7 @@ describe('CharacterJoinerService', () => {
 type IPartialLineData = ([string] | [string, number]);
 
 function lineData(data: IPartialLineData[]): IBufferLine {
-  const tline = new BufferLine(0);
+  const tline = new BufferLine(TEST_STRING_CACHE, 0);
   for (let i = 0; i < data.length; ++i) {
     const line = data[i][0];
     const attr = (data[i][1] || 0) as number;

src/browser/services/MouseService.test.ts

@@ -351,96 +351,3 @@ describe('MouseService mouseEventsRequireAlt', () => {
     assert.isFalse(element.classList.contains(MouseEventCssClasses.ENABLE_MOUSE_EVENTS));
   });
 });
-
-describe('MouseService multi-window', () => {
-  interface IRecordingDocument {
-    doc: Document;
-    added: string[];
-    removed: string[];
-    listeners: { [type: string]: EventListener[] };
-  }
-
-  function createRecordingDocument(): IRecordingDocument {
-    const added: string[] = [];
-    const removed: string[] = [];
-    const listeners: { [type: string]: EventListener[] } = {};
-    const doc = {
-      addEventListener: (type: string, listener: EventListener) => {
-        added.push(type);
-        (listeners[type] ??= []).push(listener);
-      },
-      removeEventListener: (type: string) => removed.push(type)
-    } as any;
-    return { doc, added, removed, listeners };
-  }
-
-  it('should manage protocol mouseup/mousemove listeners on the element\'s current document, not the document the terminal was opened with', () => {
-    const mouseStateService = new MouseStateService();
-    const optionsService = new OptionsService({});
-    const mouseService = new MouseService(
-      new MockRenderService(),
-      {
-        getMouseReportCoords: () => ({ col: 0, row: 0, x: 0, y: 0 })
-      } as any,
-      mouseStateService,
-      {
-        triggerDataEvent: () => {},
-        triggerBinaryEvent: () => {},
-        decPrivateModes: { applicationCursorKeys: false }
-      } as any,
-      bufferService,
-      optionsService,
-      new TestSelectionService(),
-      logService,
-      new MockCoreBrowserService()
-    );
-
-    // Simulate a terminal that was opened with one document but whose element now lives in
-    // another document (eg. it was moved to a child window)
-    const openDocument = createRecordingDocument();
-    const childDocument = createRecordingDocument();
-    const elementListeners: { [type: string]: EventListener[] } = {};
-    const element = {
-      classList: {
-        add: () => {},
-        remove: () => {},
-        contains: () => false
-      },
-      addEventListener: (type: string, listener: EventListener) => {
-        (elementListeners[type] ??= []).push(listener);
-      },
-      removeEventListener: () => {},
-      ownerDocument: childDocument.doc
-    } as any;
-
-    mouseService.bindMouse({
-      element,
-      screenElement: createTestMouseTargetElement(),
-      document: openDocument.doc
-    }, disposable => disposable, () => {});
-    mouseStateService.activeProtocol = 'ANY';
-
-    elementListeners['mousedown'][0]({
-      type: 'mousedown',
-      button: 0,
-      buttons: 1,
-      altKey: false,
-      ctrlKey: false,
-      shiftKey: false,
-      preventDefault: () => {}
-    } as any);
-    assert.deepEqual(childDocument.added, ['mouseup', 'mousemove']);
-    assert.deepEqual(openDocument.added, []);
-
-    childDocument.listeners['mouseup'][0]({
-      type: 'mouseup',
-      button: 0,
-      buttons: 0,
-      altKey: false,
-      ctrlKey: false,
-      shiftKey: false
-    } as any);
-    assert.deepEqual(childDocument.removed, ['mouseup', 'mousemove']);
-    assert.deepEqual(openDocument.removed, []);
-  });
-});

src/browser/services/MouseService.ts

@@ -7,7 +7,7 @@ import { addDisposableListener } from '../Dom';
 import { IBufferService, IMouseStateService, ICoreService, ILogService, IOptionsService } from '../../common/services/Services';
 import { CoreMouseAction, CoreMouseButton, CoreMouseEventType, ICoreMouseEvent, IDisposable } from '../../common/Types';
 import { C0 } from '../../common/data/EscapeSequences';
-import { DisposableStore, MutableDisposable } from '../../common/Lifecycle';
+import { DisposableStore, MutableDisposable, toDisposable } from '../../common/Lifecycle';
 import { ICoreBrowserService, IMouseCoordsService, IMouseService, IMouseServiceTarget, IRenderService, ISelectionService } from './Services';
 import { Gesture, EventType as GestureEventType, IGestureEvent } from '../scrollable/touch';
 
@@ -21,8 +21,6 @@ interface IMouseBindContext {
   readonly target: IMouseServiceTarget;
   readonly focus: () => void;
   readonly requestedEvents: RequestedMouseEvents;
-  readonly mouseupListener: MutableDisposable<IDisposable>;
-  readonly mousedragListener: MutableDisposable<IDisposable>;
 }
 
 export class MouseService implements IMouseService {
@@ -63,11 +61,7 @@ export class MouseService implements IMouseService {
       mousedrag: null,
       mousemove: null
     };
-    const mouseupListener = new MutableDisposable<IDisposable>();
-    const mousedragListener = new MutableDisposable<IDisposable>();
-    register(mouseupListener);
-    register(mousedragListener);
-    const ctx: IMouseBindContext = { target, focus, requestedEvents, mouseupListener, mousedragListener };
+    const ctx: IMouseBindContext = { target, focus, requestedEvents };
     const eventListeners: Record<'mouseup' | 'wheel' | 'mousedrag' | 'mousemove', EventListener> = {
       mouseup: (ev: Event) => this._handleMouseUp(ctx, ev as MouseEvent),
       wheel: (ev: Event) => this._handleWheel(ctx, ev as WheelEvent),
@@ -91,6 +85,16 @@ export class MouseService implements IMouseService {
     // force initial onProtocolChange so we dont miss early mouse requests
     this._mouseStateService.activeProtocol = this._mouseStateService.activeProtocol;
 
+    // Ensure document-level listeners are removed on dispose
+    register(toDisposable(() => {
+      if (requestedEvents.mouseup) {
+        document.removeEventListener('mouseup', requestedEvents.mouseup);
+      }
+      if (requestedEvents.mousedrag) {
+        document.removeEventListener('mousemove', requestedEvents.mousedrag);
+      }
+    }));
+
     /**
      * "Always on" event listeners.
      */
@@ -195,8 +199,12 @@ export class MouseService implements IMouseService {
     this._sendEvent(ctx, ev);
     if (!ev.buttons) {
       // if no other button is held remove global handlers
-      ctx.mouseupListener.clear();
-      ctx.mousedragListener.clear();
+      if (ctx.requestedEvents.mouseup) {
+        ctx.target.document.removeEventListener('mouseup', ctx.requestedEvents.mouseup);
+      }
+      if (ctx.requestedEvents.mousedrag) {
+        ctx.target.document.removeEventListener('mousemove', ctx.requestedEvents.mousedrag);
+      }
     }
   }
 
@@ -238,14 +246,11 @@ export class MouseService implements IMouseService {
     // of the terminal element.
     // Note: Other emulators also do this for 'mousedown' while a button
     // is held, we currently limit 'mousedown' to the terminal only.
-    // Use the element's current document in case it moved to another window after open.
-    const { element, document: targetDocument } = ctx.target;
-    const listenerDocument = element.ownerDocument ?? targetDocument;
     if (ctx.requestedEvents.mouseup) {
-      ctx.mouseupListener.value = addDisposableListener(listenerDocument, 'mouseup', ctx.requestedEvents.mouseup);
+      ctx.target.document.addEventListener('mouseup', ctx.requestedEvents.mouseup);
     }
     if (ctx.requestedEvents.mousedrag) {
-      ctx.mousedragListener.value = addDisposableListener(listenerDocument, 'mousemove', ctx.requestedEvents.mousedrag);
+      ctx.target.document.addEventListener('mousemove', ctx.requestedEvents.mousedrag);
     }
   }
 
@@ -393,7 +398,7 @@ export class MouseService implements IMouseService {
   }
 
   private _handleProtocolChange(ctx: IMouseBindContext, eventListeners: Record<'mouseup' | 'wheel' | 'mousedrag' | 'mousemove', EventListener>, events: CoreMouseEventType): void {
-    const { element } = ctx.target;
+    const { element, document } = ctx.target;
     const { requestedEvents } = ctx;
     // apply global changes on events
     if (events) {
@@ -428,14 +433,18 @@ export class MouseService implements IMouseService {
     }
 
     if (!(events & CoreMouseEventType.UP)) {
-      ctx.mouseupListener.clear();
+      if (requestedEvents.mouseup) {
+        document.removeEventListener('mouseup', requestedEvents.mouseup);
+      }
       requestedEvents.mouseup = null;
     } else {
       requestedEvents.mouseup ??= eventListeners.mouseup;
     }
 
     if (!(events & CoreMouseEventType.DRAG)) {
-      ctx.mousedragListener.clear();
+      if (requestedEvents.mousedrag) {
+        document.removeEventListener('mousemove', requestedEvents.mousedrag);
+      }
       requestedEvents.mousedrag = null;
     } else {
       requestedEvents.mousedrag ??= eventListeners.mousedrag;

src/browser/services/SelectionService.test.ts

@@ -9,11 +9,13 @@ import { SelectionModel } from '../selection/SelectionModel';
 import { IBuffer, IBufferLine } from '../../common/buffer/Types';
 import { MockBufferService, MockOptionsService, MockCoreService, MockMouseStateService, createCellData } from '../../common/TestUtils.test';
 import { BufferLine } from '../../common/buffer/BufferLine';
+import { BufferLineStringCache } from '../../common/buffer/BufferLineStringCache';
 import { IBufferService, IOptionsService } from '../../common/services/Services';
 import { MockCoreBrowserService, MockMouseService, MockRenderService } from '../TestUtils.test';
 import { CellData } from '../../common/buffer/CellData';
 import { IRenderService } from './Services';
 
+const TEST_STRING_CACHE = new BufferLineStringCache();
 
 class TestSelectionService extends SelectionService {
   constructor(
@@ -58,7 +60,7 @@ describe('SelectionService', () => {
   });
 
   function stringToRow(text: string): IBufferLine {
-    const result = new BufferLine(text.length);
+    const result = new BufferLine(TEST_STRING_CACHE, text.length);
     for (let i = 0; i < text.length; i++) {
       result.setCell(i, createCellData(0, text.charAt(i), 1));
     }
@@ -66,7 +68,7 @@ describe('SelectionService', () => {
   }
 
   function stringArrayToRow(chars: string[]): IBufferLine {
-    const line = new BufferLine(chars.length);
+    const line = new BufferLine(TEST_STRING_CACHE, chars.length);
     chars.map((c, idx) => line.setCell(idx, createCellData(0, c, 1)));
     return line;
   }
@@ -121,7 +123,7 @@ describe('SelectionService', () => {
         [0, 'o', 1, 'o'.charCodeAt(0)],
         [0, 'o', 1, 'o'.charCodeAt(0)]
       ];
-      const line = new BufferLine(data.length);
+      const line = new BufferLine(TEST_STRING_CACHE, data.length);
       for (let i = 0; i < data.length; ++i) line.setCell(i, CellData.fromCharData(data[i]));
       buffer.lines.set(0, line);
       // Ensure wide characters take up 2 columns

src/common/Event.ts

@@ -27,13 +27,11 @@ export class Emitter<T> {
       }
 
       const entry = { fn: listener, thisArgs };
-      this._listeners = this._listeners.slice();
       this._listeners.push(entry);
 
       const result = toDisposable(() => {
         const idx = this._listeners.indexOf(entry);
         if (idx !== -1) {
-          this._listeners = this._listeners.slice();
           this._listeners.splice(idx, 1);
         }
       });
@@ -52,16 +50,23 @@ export class Emitter<T> {
   }
 
   public fire(event: T): void {
-    if (this._disposed || !this._listeners.length) {
+    if (this._disposed) {
       return;
     }
-    if (this._listeners.length === 1) {
-      this._listeners[0].fn.call(this._listeners[0].thisArgs, event);
-      return;
-    }
-    const listeners = this._listeners;
-    for (let i = 0, len = listeners.length; i < len; ++i) {
-      listeners[i].fn.call(listeners[i].thisArgs, event);
+    switch (this._listeners.length) {
+      case 0: return;
+      case 1: {
+        const { fn, thisArgs } = this._listeners[0];
+        fn.call(thisArgs, event);
+        return;
+      }
+      default: {
+        // Snapshot listeners to allow modifications during iteration (2+ listeners)
+        const listeners = this._listeners.slice();
+        for (const { fn, thisArgs } of listeners) {
+          fn.call(thisArgs, event);
+        }
+      }
     }
   }
 

src/common/InputHandler.test.ts

@@ -2394,54 +2394,6 @@ describe('InputHandler', () => {
     });
   });
 
-  describe('ED3 - erase saved lines', () => {
-    beforeEach(() => {
-      bufferService.resize(10, 5);
-    });
-    it('should stop locking the viewport when the scrollback the user scrolled into is erased', async () => {
-      for (let i = 0; i < 20; ++i) {
-        await inputHandler.parseP(`old ${i}\r\n`);
-      }
-      bufferService.scrollLines(-5);
-      assert.strictEqual(bufferService.isUserScrolling, true);
-
-      await inputHandler.parseP('\x1b[3J');
-
-      assert.strictEqual(bufferService.isUserScrolling, false);
-      assert.strictEqual(bufferService.buffer.ybase, 0);
-      assert.strictEqual(bufferService.buffer.ydisp, 0);
-
-      for (let i = 0; i < 20; ++i) {
-        await inputHandler.parseP(`new ${i}\r\n`);
-      }
-
-      assert.strictEqual(bufferService.buffer.ydisp, bufferService.buffer.ybase);
-    });
-    it('should not reset the scroll position when erasing scrollback on a resized alt buffer', async () => {
-      bufferService.resize(10, 50);
-      bufferService.resize(10, 5);
-      for (let i = 0; i < 20; ++i) {
-        await inputHandler.parseP(`old ${i}\r\n`);
-      }
-      bufferService.scrollLines(-5);
-      const ydisp = bufferService.buffer.ydisp;
-
-      await inputHandler.parseP('\x1b[?1049h');
-      for (let i = 0; i < 20; ++i) {
-        await inputHandler.parseP(`new ${i}\r\n`);
-      }
-      await inputHandler.parseP('\x1b[3J\x1b[?1049l');
-
-      assert.strictEqual(bufferService.isUserScrolling, true);
-      assert.strictEqual(bufferService.buffer.ydisp, ydisp);
-
-      await inputHandler.parseP('more\r\n');
-
-      assert.strictEqual(bufferService.isUserScrolling, true);
-      assert.strictEqual(bufferService.buffer.ydisp, ydisp);
-    });
-  });
-
   describe('DECSCA and DECSED/DECSEL', () => {
     it('default is unprotected', async () => {
       await inputHandler.parseP('some text');

src/common/InputHandler.ts

@@ -1286,11 +1286,6 @@ export class InputHandler extends Disposable implements IInputHandler {
           this._activeBuffer.lines.trimStart(scrollBackSize);
           this._activeBuffer.ybase = Math.max(this._activeBuffer.ybase - scrollBackSize, 0);
           this._activeBuffer.ydisp = Math.max(this._activeBuffer.ydisp - scrollBackSize, 0);
-          // isUserScrolling tracks the normal buffer's viewport, so ED3 on the alt
-          // screen must not touch it
-          if (this._activeBuffer === this._bufferService.buffers.normal) {
-            this._bufferService.isUserScrolling = false;
-          }
           // Force a scroll event to refresh viewport
           this._onScroll.fire(0);
         }

src/common/buffer/AttributeData.ts

@@ -139,7 +139,6 @@ export class AttributeData implements IAttributeData {
  */
 export class ExtendedAttrs implements IExtendedAttrs {
   private _ext: number = 0;
-  public payload: Object | undefined;
   public get ext(): number {
     if (this._urlId) {
       return (
@@ -208,6 +207,6 @@ export class ExtendedAttrs implements IExtendedAttrs {
    * that needs to be persistant in the buffer.
    */
   public isEmpty(): boolean {
-    return this.underlineStyle === UnderlineStyle.NONE && this._urlId === 0 && this.payload === undefined;
+    return this.underlineStyle === UnderlineStyle.NONE && this._urlId === 0;
   }
 }

src/common/buffer/Buffer.test.ts

@@ -8,14 +8,24 @@ import { Buffer } from './Buffer';
 import { CircularList } from '../CircularList';
 import { MockOptionsService, MockBufferService, MockLogService, createCellData } from '../TestUtils.test';
 import { BufferLine, DEFAULT_ATTR_DATA } from './BufferLine';
+import { BufferLineStringCache } from './BufferLineStringCache';
 import { CellData } from './CellData';
-
+import { ExtendedAttrs } from './AttributeData';
 
 const INIT_COLS = 80;
 const INIT_ROWS = 24;
 const INIT_SCROLLBACK = 1000;
+const TEST_STRING_CACHE = new BufferLineStringCache();
 
-class TestBuffer extends Buffer {}
+class TestBuffer extends Buffer {
+  public getStringCache(): BufferLineStringCache {
+    return (this as unknown as { _stringCache: BufferLineStringCache })._stringCache;
+  }
+
+  public getStringCacheClearTimeout(): unknown {
+    return (this.getStringCache() as unknown as { _clearTimeout: { value: unknown } })._clearTimeout.value;
+  }
+}
 
 describe('Buffer', () => {
   let optionsService: MockOptionsService;
@@ -1192,7 +1202,7 @@ describe('Buffer', () => {
 
   describe ('translateBufferLineToString', () => {
     it('should handle selecting a section of ascii text', () => {
-      const line = new BufferLine(4);
+      const line = new BufferLine(TEST_STRING_CACHE, 4);
       line.setCell(0, createCellData(0, 'a', 1));
       line.setCell(1, createCellData(0, 'b', 1));
       line.setCell(2, createCellData(0, 'c', 1));
@@ -1204,7 +1214,7 @@ describe('Buffer', () => {
     });
 
     it('should handle a cut-off double width character by including it', () => {
-      const line = new BufferLine(3);
+      const line = new BufferLine(TEST_STRING_CACHE, 3);
       line.setCell(0, createCellData(0, '語', 2));
       line.setCell(1, createCellData(0, '', 0));
       line.setCell(2, createCellData(0, 'a', 1));
@@ -1215,7 +1225,7 @@ describe('Buffer', () => {
     });
 
     it('should handle a zero width character in the middle of the string by not including it', () => {
-      const line = new BufferLine(3);
+      const line = new BufferLine(TEST_STRING_CACHE, 3);
       line.setCell(0, createCellData(0, '語', 2));
       line.setCell(1, createCellData(0, '', 0));
       line.setCell(2, createCellData(0, 'a', 1));
@@ -1232,7 +1242,7 @@ describe('Buffer', () => {
     });
 
     it('should handle single width emojis', () => {
-      const line = new BufferLine(2);
+      const line = new BufferLine(TEST_STRING_CACHE, 2);
       line.setCell(0, createCellData(0, '😁', 1));
       line.setCell(1, createCellData(0, 'a', 1));
       buffer.lines.set(0, line);
@@ -1245,7 +1255,7 @@ describe('Buffer', () => {
     });
 
     it('should handle double width emojis', () => {
-      const line = new BufferLine(2);
+      const line = new BufferLine(TEST_STRING_CACHE, 2);
       line.setCell(0, createCellData(0, '😁', 2));
       line.setCell(1, createCellData(0, '', 0));
       buffer.lines.set(0, line);
@@ -1256,7 +1266,7 @@ describe('Buffer', () => {
       const str2 = buffer.translateBufferLineToString(0, true, 0, 2);
       assert.equal(str2, '😁');
 
-      const line2 = new BufferLine(3);
+      const line2 = new BufferLine(TEST_STRING_CACHE, 3);
       line2.setCell(0, createCellData(0, '😁', 2));
       line2.setCell(1, createCellData(0, '', 0));
       line2.setCell(2, createCellData(0, 'a', 1));
@@ -1267,6 +1277,99 @@ describe('Buffer', () => {
     });
   });
 
+  describe('line string cache cleanup', () => {
+    it('should clear shared cache entries with a single timer', () => {
+      const originalSetTimeout = globalThis.setTimeout;
+      const originalClearTimeout = globalThis.clearTimeout;
+      const originalDateNow = Date.now;
+      let timeoutId = 0;
+      let now = 0;
+      const clearedTimeouts: number[] = [];
+      const scheduledTimeouts = new Map<number, { delay: number, fire: () => void }>();
+      (globalThis as any).setTimeout = ((handler: (...args: any[]) => void, timeout?: number) => {
+        const id = ++timeoutId;
+        scheduledTimeouts.set(id, {
+          delay: timeout ?? 0,
+          fire: () => {
+            scheduledTimeouts.delete(id);
+            handler();
+          }
+        });
+        return id as ReturnType<typeof setTimeout>;
+      }) as typeof setTimeout;
+      (globalThis as any).clearTimeout = ((id: ReturnType<typeof setTimeout>) => {
+        const numericId = id as unknown as number;
+        clearedTimeouts.push(numericId);
+        scheduledTimeouts.delete(numericId);
+      }) as typeof clearTimeout;
+      Date.now = () => now;
+      try {
+        buffer.fillViewportRows();
+        buffer.lines.get(0)!.setCell(0, createCellData(0, 'a', 1));
+        buffer.lines.get(1)!.setCell(0, createCellData(0, 'b', 1));
+
+        assert.equal(buffer.translateBufferLineToString(0, false), `a${' '.repeat(INIT_COLS - 1)}`);
+        assert.equal(buffer.translateBufferLineToString(1, false), `b${' '.repeat(INIT_COLS - 1)}`);
+
+        const cache = buffer.getStringCache();
+        assert.equal(cache.entries.size, 2);
+        assert.ok(buffer.getStringCacheClearTimeout() !== undefined);
+        assert.equal(scheduledTimeouts.size, 1);
+        assert.equal([...scheduledTimeouts.values()][0].delay, 15000);
+        const initialTimerCreationCount = timeoutId;
+
+        now = 5000;
+        assert.equal(buffer.translateBufferLineToString(0, false), `a${' '.repeat(INIT_COLS - 1)}`);
+        assert.equal(timeoutId, initialTimerCreationCount);
+        assert.equal(scheduledTimeouts.size, 1);
+        assert.deepEqual(clearedTimeouts, []);
+
+        now = 15000;
+        [...scheduledTimeouts.values()][0].fire();
+        assert.equal(timeoutId, initialTimerCreationCount + 1);
+        assert.ok(buffer.getStringCacheClearTimeout() !== undefined);
+        assert.equal(scheduledTimeouts.size, 1);
+        assert.equal([...scheduledTimeouts.values()][0].delay, 5000);
+
+        now = 20000;
+        [...scheduledTimeouts.values()][0].fire();
+
+        assert.equal(cache.entries.size, 0);
+        assert.equal(buffer.getStringCacheClearTimeout(), undefined);
+
+        assert.equal(buffer.translateBufferLineToString(0, false), `a${' '.repeat(INIT_COLS - 1)}`);
+        assert.equal(cache.entries.size, 1);
+      } finally {
+        Date.now = originalDateNow;
+        globalThis.setTimeout = originalSetTimeout;
+        globalThis.clearTimeout = originalClearTimeout;
+      }
+    });
+
+    it('should reset line string cache state on clear and resize', () => {
+      buffer.fillViewportRows();
+      buffer.lines.get(0)!.setCell(0, createCellData(0, 'a', 1));
+      buffer.translateBufferLineToString(0, false);
+
+      const cache = buffer.getStringCache();
+      assert.equal(cache.entries.size, 1);
+      assert.ok(buffer.getStringCacheClearTimeout() !== undefined);
+
+      buffer.clear();
+      assert.equal(cache.entries.size, 0);
+      assert.equal(buffer.getStringCacheClearTimeout(), undefined);
+
+      buffer.fillViewportRows();
+      buffer.lines.get(0)!.setCell(0, createCellData(0, 'b', 1));
+      buffer.translateBufferLineToString(0, false);
+      assert.equal(cache.entries.size, 1);
+
+      buffer.resize(INIT_COLS - 1, INIT_ROWS);
+      assert.equal(cache.entries.size, 0);
+      assert.equal(buffer.getStringCacheClearTimeout(), undefined);
+    });
+  });
+
   describe('memory cleanup after shrinking', () => {
     it('should realign memory from idle task execution', async () => {
       buffer.fillViewportRows();

src/common/buffer/Buffer.ts

@@ -10,6 +10,7 @@ import { ICharset } from '../Types';
 import { IAttributeData, IBuffer, IBufferLine, ICellData } from './Types';
 import { ExtendedAttrs } from './AttributeData';
 import { BufferLine, DEFAULT_ATTR_DATA } from './BufferLine';
+import { BufferLineStringCache } from './BufferLineStringCache';
 import { getWrappedLineTrimmedLength, reflowLargerApplyNewLayout, reflowLargerCreateNewLayout, reflowLargerGetLinesToRemove, reflowSmallerGetNewLineLengths } from './BufferReflow';
 import { CellData } from './CellData';
 import { NULL_CELL_CHAR, NULL_CELL_CODE, NULL_CELL_WIDTH, WHITESPACE_CELL_CHAR, WHITESPACE_CELL_CODE, WHITESPACE_CELL_WIDTH } from './Constants';
@@ -51,6 +52,7 @@ export class Buffer extends Disposable implements IBuffer {
   private _isClearing: boolean = false;
   private _memoryCleanupQueue: InstanceType<typeof IdleTaskQueue>;
   private _memoryCleanupPosition = 0;
+  private readonly _stringCache: BufferLineStringCache;
 
   constructor(
     private _hasScrollback: boolean,
@@ -68,6 +70,7 @@ export class Buffer extends Disposable implements IBuffer {
     this._memoryCleanupQueue = new IdleTaskQueue(this._logService);
     this._register(toDisposable(() => this._memoryCleanupQueue.clear()));
     this._register(toDisposable(() => this.clearAllMarkers()));
+    this._stringCache = this._register(new BufferLineStringCache());
   }
 
   public getNullCell(attr?: IAttributeData): ICellData {
@@ -97,7 +100,7 @@ export class Buffer extends Disposable implements IBuffer {
   }
 
   public getBlankLine(attr: IAttributeData, isWrapped?: boolean): IBufferLine {
-    return new BufferLine(this._bufferService.cols, this.getNullCell(attr), isWrapped);
+    return new BufferLine(this._stringCache, this._bufferService.cols, this.getNullCell(attr), isWrapped);
   }
 
   public get hasScrollback(): boolean {
@@ -142,6 +145,7 @@ export class Buffer extends Disposable implements IBuffer {
    * Clears the buffer to its initial state, discarding all previous data.
    */
   public clear(): void {
+    this._stringCache.clear();
     this.ydisp = 0;
     this.ybase = 0;
     this.y = 0;
@@ -160,6 +164,7 @@ export class Buffer extends Disposable implements IBuffer {
   public resize(newCols: number, newRows: number): void {
     // store reference to null cell with default attrs
     const nullCell = this.getNullCell(DEFAULT_ATTR_DATA);
+    this._stringCache.clear();
 
     // count bufferlines with overly big memory to be cleaned afterwards
     let dirtyMemoryLines = 0;
@@ -194,7 +199,7 @@ export class Buffer extends Disposable implements IBuffer {
             if (this._optionsService.rawOptions.windowsPty.backend !== undefined || this._optionsService.rawOptions.windowsPty.buildNumber !== undefined) {
               // Just add the new missing rows on Windows as conpty reprints the screen with its
               // view of the world. Once a line enters scrollback for conpty it remains there
-              this.lines.push(new BufferLine(newCols, nullCell, false));
+              this.lines.push(new BufferLine(this._stringCache, newCols, nullCell, false));
             } else {
               if (this.ybase > 0 && this.lines.length <= this.ybase + this.y + addToY + 1) {
                 // There is room above the buffer and there are no empty elements below the line,
@@ -208,7 +213,7 @@ export class Buffer extends Disposable implements IBuffer {
               } else {
                 // Add a blank line if there is no buffer left at the top to scroll to, or if there
                 // are blank lines after the cursor
-                this.lines.push(new BufferLine(newCols, nullCell, false));
+                this.lines.push(new BufferLine(this._stringCache, newCols, nullCell, false));
               }
             }
           }
@@ -349,7 +354,7 @@ export class Buffer extends Disposable implements IBuffer {
         }
         if (this.lines.length < newRows) {
           // Add an extra row at the bottom of the viewport
-          this.lines.push(new BufferLine(newCols, nullCell, false));
+          this.lines.push(new BufferLine(this._stringCache, newCols, nullCell, false));
         }
       } else {
         if (this.ydisp === this.ybase) {

src/common/buffer/BufferLine.test.ts

@@ -4,16 +4,19 @@
  */
 import { NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE, DEFAULT_ATTR, Content, UnderlineStyle, BgFlags, Attributes, FgFlags } from './Constants';
 import { BufferLine } from './BufferLine';
+import { BufferLineStringCache } from './BufferLineStringCache';
 import { CellData } from './CellData';
 import { CharData, IBufferLine, ICellData } from './Types';
 import { assert } from 'chai';
 import { AttributeData } from './AttributeData';
 import { createCellData, NULL_CELL_DATA, extendedAttributes } from '../TestUtils.test';
 
+const TEST_STRING_CACHE = new BufferLineStringCache();
+
 
 class TestBufferLine extends BufferLine {
   constructor(cols: number, fillCellData?: ICellData, isWrapped: boolean = false) {
-    super(cols, fillCellData, isWrapped);
+    super(TEST_STRING_CACHE, cols, fillCellData, isWrapped);
   }
 
   public get combined(): {[index: number]: string} {
@@ -21,19 +24,19 @@ class TestBufferLine extends BufferLine {
   }
 
   public get cachedString(): string | undefined {
-    return this._cacheValid ? this._cache : undefined;
+    return this._getStringCacheEntry(false)?.value;
   }
 
   public set cachedString(value: string | undefined) {
-    this._cache = value ?? '';
+    this._getStringCacheEntry(true)!.value = value;
   }
 
   public get isCachedStringTrimmed(): boolean {
-    return this._cacheTrimmed;
+    return this._getStringCacheEntry(false)?.isTrimmed ?? false;
   }
 
   public set isCachedStringTrimmed(value: boolean) {
-    this._cacheTrimmed = value;
+    this._getStringCacheEntry(true)!.isTrimmed = value;
   }
 
   public toArray(): CharData[] {

src/common/buffer/BufferLine.ts

@@ -8,6 +8,7 @@ import { AttributeData } from './AttributeData';
 import { CellData } from './CellData';
 import { Attributes, BgFlags, CHAR_DATA_ATTR_INDEX, CHAR_DATA_CHAR_INDEX, CHAR_DATA_WIDTH_INDEX, Content, NULL_CELL_CHAR, NULL_CELL_CODE, NULL_CELL_WIDTH, WHITESPACE_CELL_CHAR } from './Constants';
 import { stringFromCodePoint } from '../input/TextDecoder';
+import { StringBuilder } from '../StringBuilder';
 
 // Buffer memory layout:
 //
@@ -36,20 +37,24 @@ const enum Cell {
   BG = 2  // currently unused
 }
 
-
-interface IExtendedAttrsExt extends IExtendedAttrs {
-  _ext: number;
-  _urlId: number;
-}
-
-
 export const DEFAULT_ATTR_DATA = Object.freeze(new AttributeData());
 
 // Work variables to avoid garbage collection
 let $startIndex = 0;
 const $workCell = new CellData();
-const $extended = DEFAULT_ATTR_DATA.extended.clone() as IExtendedAttrsExt;
+const $translateToStringBuilder = new StringBuilder();
 
+export interface IBufferLineStringCacheEntry {
+  value: string | undefined;
+  isTrimmed: boolean;
+  generation: number;
+}
+
+export interface IBufferLineStringCache {
+  generation: number;
+  allocateEntry(): IBufferLineStringCacheEntry;
+  touch?(): void;
+}
 
 /**
  * Typed array based bufferline implementation.
@@ -66,20 +71,25 @@ const $extended = DEFAULT_ATTR_DATA.extended.clone() as IExtendedAttrsExt;
  * (if only one particular value is needed) or `loadCell`. For `loadCell` in a loop
  * memory allocs / GC pressure can be greatly reduced by reusing the CellData object.
  */
+/**
+ * Shared empty sparse map for lines with no combining data.
+ * Uses a sentinel + copy-on-write so `copyFrom` can detect empty `_combined` with
+ * reference equality. `_extendedAttrs` uses `undefined` instead (addon-image writes
+ * the map directly without BufferLine APIs).
+ */
+const EMPTY_SPARSE_MAP: {[index: number]: string} = Object.create(null);
+
 export class BufferLine implements IBufferLine {
   protected _data: Uint32Array;
   /** Sparse cache; only read when `IS_COMBINED_MASK` is set in `_data`. */
-  protected _combined: {[index: number]: string} = {};
+  protected _combined: {[index: number]: string} = EMPTY_SPARSE_MAP;
   /** Sparse cache; only read when `HAS_EXTENDED` is set in `_data`. */
-  protected _extendedAttrs: {[index: number]: IExtendedAttrs | undefined} = {};
+  protected _extendedAttrs: {[index: number]: IExtendedAttrs | undefined} | undefined;
+  protected _stringCacheEntryRef: WeakRef<IBufferLineStringCacheEntry> | undefined;
   public length: number;
 
-  /** line text cache */
-  protected _cacheValid = false;
-  protected _cache: string = '';
-  protected _cacheTrimmed = false;
-
   constructor(
+    protected readonly _stringCache: IBufferLineStringCache,
     cols: number,
     fillCellData?: ICellData,
     public isWrapped: boolean = false
@@ -116,9 +126,10 @@ export class BufferLine implements IBufferLine {
    * @deprecated
    */
   public set(index: number, value: CharData): void {
-    this._cacheValid = false;
+    this._invalidateStringCache();
     this._data[index * Constants.CELL_INDICIES + Cell.FG] = value[CHAR_DATA_ATTR_INDEX];
     if (value[CHAR_DATA_CHAR_INDEX].length > 1) {
+      this._ensureCombinedMap();
       this._combined[index] = value[1];
       this._data[index * Constants.CELL_INDICIES + Cell.CONTENT] = index | Content.IS_COMBINED_MASK | (value[CHAR_DATA_WIDTH_INDEX] << Content.WIDTH_SHIFT);
     } else {
@@ -208,35 +219,27 @@ export class BufferLine implements IBufferLine {
     } else {
       cell.combinedData = '';
     }
-    cell.extended = this.getExtended(index);
-    return cell;
-  }
-
-  public getExtended(index: number): IExtendedAttrs {
-    $startIndex = index * Constants.CELL_INDICIES;
-    if (this._data[$startIndex + Cell.BG] & BgFlags.HAS_EXTENDED) {
-      return this._extendedAttrs[index]!;
+    if (cell.bg & BgFlags.HAS_EXTENDED) {
+      cell.extended = this._extendedAttrs![index]!;
+    } else {
+      // Do not mutate cell.extended in place: it may still reference this line's map entry from a
+      // prior loadCell into a reused CellData (e.g. $workCell during insert/delete).
+      cell.extended = DEFAULT_ATTR_DATA.extended.clone();
     }
-    // Do not mutate cell.extended in place: it may still reference this line's map entry from a
-    // prior loadCell into a reused CellData (e.g. $workCell during insert/delete).
-    // We use $extended as blueprint and reset the internals
-    // mimicking the ctor to avoid a new allocation.
-    $extended._ext = 0;
-    $extended._urlId = 0;
-    $extended.payload = undefined;
-    return $extended;
+    return cell;
   }
 
   /**
    * Set data at `index` to `cell`.
    */
   public setCell(index: number, cell: ICellData): void {
-    this._cacheValid = false;
+    this._invalidateStringCache();
     if (cell.content & Content.IS_COMBINED_MASK) {
+      this._ensureCombinedMap();
       this._combined[index] = cell.combinedData;
     }
     if (cell.bg & BgFlags.HAS_EXTENDED) {
-      this._extendedAttrs[index] = cell.extended;
+      this._ensureExtendedAttrsMap()[index] = cell.extended;
     }
     this._data[index * Constants.CELL_INDICIES + Cell.CONTENT] = cell.content;
     this._data[index * Constants.CELL_INDICIES + Cell.FG] = cell.fg;
@@ -249,14 +252,13 @@ export class BufferLine implements IBufferLine {
    * it gets an optimized access method.
    */
   public setCellFromCodepoint(index: number, codePoint: number, width: number, attrs: IAttributeData): void {
-    this._cacheValid = false;
+    this._invalidateStringCache();
     if (attrs.bg & BgFlags.HAS_EXTENDED) {
-      this._extendedAttrs[index] = attrs.extended;
+      this._ensureExtendedAttrsMap()[index] = attrs.extended;
     }
-    const $idx = index * Constants.CELL_INDICIES;
-    this._data[$idx + Cell.CONTENT] = codePoint | (width << Content.WIDTH_SHIFT);
-    this._data[$idx + Cell.FG] = attrs.fg;
-    this._data[$idx + Cell.BG] = attrs.bg;
+    this._data[index * Constants.CELL_INDICIES + Cell.CONTENT] = codePoint | (width << Content.WIDTH_SHIFT);
+    this._data[index * Constants.CELL_INDICIES + Cell.FG] = attrs.fg;
+    this._data[index * Constants.CELL_INDICIES + Cell.BG] = attrs.bg;
   }
 
   /**
@@ -266,16 +268,18 @@ export class BufferLine implements IBufferLine {
    * by the previous `setDataFromCodePoint` call, we can omit it here.
    */
   public addCodepointToCell(index: number, codePoint: number, width: number): void {
-    this._cacheValid = false;
+    this._invalidateStringCache();
     let content = this._data[index * Constants.CELL_INDICIES + Cell.CONTENT];
     if (content & Content.IS_COMBINED_MASK) {
       // we already have a combined string, simply add
+      this._ensureCombinedMap();
       this._combined[index] += stringFromCodePoint(codePoint);
     } else {
       if (content & Content.CODEPOINT_MASK) {
         // normal case for combining chars:
         //  - move current leading char + new one into combined string
         //  - set combined flag
+        this._ensureCombinedMap();
         this._combined[index] = stringFromCodePoint(content & Content.CODEPOINT_MASK) + stringFromCodePoint(codePoint);
         content &= ~Content.CODEPOINT_MASK; // set codepoint in buffer to 0
         content |= Content.IS_COMBINED_MASK;
@@ -293,7 +297,7 @@ export class BufferLine implements IBufferLine {
   }
 
   public insertCells(pos: number, n: number, fillCellData: ICellData): void {
-    this._cacheValid = false;
+    this._invalidateStringCache();
     pos %= this.length;
 
     // handle fullwidth at pos: reset cell one to the left if pos is second cell of a wide char
@@ -321,7 +325,7 @@ export class BufferLine implements IBufferLine {
   }
 
   public deleteCells(pos: number, n: number, fillCellData: ICellData): void {
-    this._cacheValid = false;
+    this._invalidateStringCache();
     pos %= this.length;
     if (n < this.length - pos) {
       for (let i = 0; i < this.length - pos - n; ++i) {
@@ -348,7 +352,7 @@ export class BufferLine implements IBufferLine {
   }
 
   public replaceCells(start: number, end: number, fillCellData: ICellData, respectProtect: boolean = false): void {
-    this._cacheValid = false;
+    this._invalidateStringCache();
     // full branching on respectProtect==true, hopefully getting fast JIT for standard case
     if (respectProtect) {
       if (start && this.getWidth(start - 1) === 2 && !this.isProtected(start - 1)) {
@@ -388,7 +392,7 @@ export class BufferLine implements IBufferLine {
    * excess memory (true after shrinking > Constants.CLEANUP_THRESHOLD).
    */
   public resize(cols: number, fillCellData: ICellData): boolean {
-    this._cacheValid = false;
+    this._invalidateStringCache();
     if (cols === this.length) {
       return this._data.length * 4 * Constants.CLEANUP_THRESHOLD < this._data.buffer.byteLength;
     }
@@ -418,11 +422,13 @@ export class BufferLine implements IBufferLine {
         }
       }
       // remove any cut off extended attributes
-      const extKeys = Object.keys(this._extendedAttrs);
-      for (let i = 0; i < extKeys.length; i++) {
-        const key = parseInt(extKeys[i], 10);
-        if (key >= cols) {
-          delete this._extendedAttrs[key];
+      if (this._extendedAttrs) {
+        const extKeys = Object.keys(this._extendedAttrs);
+        for (let i = 0; i < extKeys.length; i++) {
+          const key = parseInt(extKeys[i], 10);
+          if (key >= cols) {
+            delete this._extendedAttrs[key];
+          }
         }
       }
     }
@@ -448,7 +454,7 @@ export class BufferLine implements IBufferLine {
 
   /** fill a line with fillCharData */
   public fill(fillCellData: ICellData, respectProtect: boolean = false): void {
-    this._cacheValid = false;
+    this._invalidateStringCache();
     // full branching on respectProtect==true, hopefully getting fast JIT for standard case
     if (respectProtect) {
       for (let i = 0; i < this.length; ++i) {
@@ -458,15 +464,16 @@ export class BufferLine implements IBufferLine {
       }
       return;
     }
-    this._combined = {};
-    this._extendedAttrs = {};
+    this._combined = EMPTY_SPARSE_MAP;
+    this._extendedAttrs = undefined;
     for (let i = 0; i < this.length; ++i) {
       this.setCell(i, fillCellData);
     }
   }
 
   /** alter to a full copy of line  */
-  public copyFrom(line: BufferLine, blank?: boolean): void {
+  public copyFrom(line: BufferLine): void {
+    this._invalidateStringCache();
     if (this.length !== line.length) {
       this._data = new Uint32Array(line._data);
     } else {
@@ -474,29 +481,16 @@ export class BufferLine implements IBufferLine {
       this._data.set(line._data);
     }
     this.length = line.length;
-    if (blank) {
-      // a blank line may never hold combined or extended attrs,
-      // thus we can skip handling them
-      this._combined = {};
-      this._extendedAttrs = {};
-    } else {
-      this._copySparseMapsFrom(line);
-    }
-    this._cache = '';
-    this._cacheValid = false;
+    this._copySparseMapsFrom(line);
     this.isWrapped = line.isWrapped;
   }
 
   /** create a new clone */
-  public clone(blank?: boolean): IBufferLine {
-    const newLine = new BufferLine(0, undefined, false);
+  public clone(): IBufferLine {
+    const newLine = new BufferLine(this._stringCache, 0, undefined, false);
     newLine._data = new Uint32Array(this._data);
     newLine.length = this.length;
-    if (!blank) {
-      // a blank line may never hold combined or extended attrs,
-      // thus we can skip handling them
-      newLine._copySparseMapsFrom(this);
-    }
+    newLine._copySparseMapsFrom(this);
     newLine.isWrapped = this.isWrapped;
     return newLine;
   }
@@ -520,7 +514,7 @@ export class BufferLine implements IBufferLine {
   }
 
   public copyCellsFrom(src: BufferLine, srcCol: number, destCol: number, length: number, applyInReverse: boolean): void {
-    this._cacheValid = false;
+    this._invalidateStringCache();
     const srcData = src._data;
     if (applyInReverse) {
       for (let cell = length - 1; cell >= 0; cell--) {
@@ -554,13 +548,17 @@ export class BufferLine implements IBufferLine {
    * returned string, the corresponding entries in `outColumns` will have the same column number.
    */
   public translateToString(trimRight?: boolean, startCol?: number, endCol?: number, outColumns?: number[]): string {
-    const isCanonical = (startCol === undefined || startCol === 0) && endCol === undefined && outColumns === undefined;
-    if (isCanonical && this._cacheValid) {
+    const isCanonicalRequest = (startCol === undefined || startCol === 0) && endCol === undefined && outColumns === undefined;
+    if (isCanonicalRequest) {
+      this._stringCache.touch?.();
+    }
+    const stringCacheEntry = isCanonicalRequest ? this._getStringCacheEntry(false) : undefined;
+    if (isCanonicalRequest && stringCacheEntry?.value !== undefined) {
       if (trimRight) {
-        return this._cacheTrimmed ? this._cache : this._cache.trimEnd();
+        return stringCacheEntry.isTrimmed ? stringCacheEntry.value : stringCacheEntry.value.trimEnd();
       }
-      if (!this._cacheTrimmed) {
-        return this._cache;
+      if (!stringCacheEntry.isTrimmed) {
+        return stringCacheEntry.value;
       }
     }
     startCol = startCol ?? 0;
@@ -571,12 +569,12 @@ export class BufferLine implements IBufferLine {
     if (outColumns) {
       outColumns.length = 0;
     }
-    const cellContents: string[] = [];
+    $translateToStringBuilder.reset();
     while (startCol < endCol) {
       const content = this._data[startCol * Constants.CELL_INDICIES + Cell.CONTENT];
       const cp = content & Content.CODEPOINT_MASK;
       const chars = (content & Content.IS_COMBINED_MASK) ? this._combined[startCol] : (cp) ? stringFromCodePoint(cp) : WHITESPACE_CELL_CHAR;
-      cellContents.push(chars);
+      $translateToStringBuilder.append(chars);
       if (outColumns) {
         for (let i = 0; i < chars.length; ++i) {
           outColumns.push(startCol);
@@ -587,32 +585,94 @@ export class BufferLine implements IBufferLine {
     if (outColumns) {
       outColumns.push(startCol);
     }
-    const result = cellContents.join('');
-    if (isCanonical) {
-      this._cache = result;
-      this._cacheValid = true;
-      this._cacheTrimmed = !!trimRight;
+    const result = $translateToStringBuilder.toString();
+    $translateToStringBuilder.reset();
+    if (isCanonicalRequest) {
+      const cacheEntry = this._getStringCacheEntry(true)!;
+      cacheEntry.value = result;
+      cacheEntry.isTrimmed = !!trimRight;
     }
     return result;
   }
 
+  protected _getStringCacheEntry(createIfNeeded: boolean): IBufferLineStringCacheEntry | undefined {
+    const cachedEntry = this._stringCacheEntryRef?.deref();
+    if (cachedEntry) {
+      if (cachedEntry.generation === this._stringCache.generation) {
+        return cachedEntry;
+      }
+    }
+    if (!createIfNeeded) {
+      return undefined;
+    }
+    const cacheEntry = this._stringCache.allocateEntry();
+    this._stringCacheEntryRef = new WeakRef(cacheEntry);
+    return cacheEntry;
+  }
+
+  private _invalidateStringCache(): void {
+    const cacheEntry = this._getStringCacheEntry(false);
+    if (cacheEntry) {
+      cacheEntry.value = undefined;
+      cacheEntry.isTrimmed = false;
+    }
+  }
+
   /** Copy sparse map entries for a single cell when `_data` flags require them. */
   private _copyCellMapsFrom(src: BufferLine, srcCol: number, destCol: number): void {
     const srcStart = srcCol * Constants.CELL_INDICIES;
     if (src._data[srcStart + Cell.CONTENT] & Content.IS_COMBINED_MASK) {
+      this._ensureCombinedMap();
       this._combined[destCol] = src._combined[srcCol];
     }
     if (src._data[srcStart + Cell.BG] & BgFlags.HAS_EXTENDED) {
-      this._extendedAttrs[destCol] = src._extendedAttrs[srcCol];
+      this._ensureExtendedAttrsMap()[destCol] = src._extendedAttrs![srcCol]!;
     }
   }
 
   /** Rebuild sparse maps from another line, keyed only by `_data` flags. */
   private _copySparseMapsFrom(line: BufferLine): void {
+    const srcCombined = line._combined;
+    const srcExtended = line._extendedAttrs;
+
+    // Fast path: blank / scroll-recycle source (empty `_combined` sentinel, no extended map).
+    if (srcCombined === EMPTY_SPARSE_MAP && !srcExtended) {
+      this._combined = EMPTY_SPARSE_MAP;
+      this._extendedAttrs = undefined;
+      return;
+    }
+    this._copySparseMapsFromDense(line);
+  }
+
+  /** Copy sparse maps by scanning `_data` flags (inlined, no per-cell function calls). */
+  private _copySparseMapsFromDense(line: BufferLine): void {
     this._combined = {};
     this._extendedAttrs = {};
-    for (let i = 0; i < line.length; i++) {
-      this._copyCellMapsFrom(line, i, i);
+    const srcData = line._data;
+    const srcCombined = line._combined;
+    const srcExtended = line._extendedAttrs;
+    const len = line.length;
+    const indices = Constants.CELL_INDICIES;
+    const combined = this._combined;
+    const extendedAttrs = this._extendedAttrs;
+    for (let i = 0; i < len; i++) {
+      const start = i * indices;
+      if (srcData[start + Cell.CONTENT] & Content.IS_COMBINED_MASK) {
+        combined[i] = srcCombined[i];
+      }
+      if (srcData[start + Cell.BG] & BgFlags.HAS_EXTENDED) {
+        extendedAttrs[i] = srcExtended![i];
+      }
     }
   }
+
+  private _ensureCombinedMap(): void {
+    if (this._combined === EMPTY_SPARSE_MAP) {
+      this._combined = {};
+    }
+  }
+
+  private _ensureExtendedAttrsMap(): {[index: number]: IExtendedAttrs | undefined} {
+    return this._extendedAttrs ??= {};
+  }
 }

src/common/buffer/BufferLineStringCache.ts

@@ -0,0 +1,69 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import type { IBufferLineStringCache, IBufferLineStringCacheEntry } from './BufferLine';
+import { disposableTimeout } from '../Async';
+import { Disposable, MutableDisposable, toDisposable, type IDisposable } from '../Lifecycle';
+
+const enum Constants {
+  CACHE_TTL_MS = 15000
+}
+
+export class BufferLineStringCache extends Disposable implements IBufferLineStringCache {
+  public generation: number = 0;
+  public readonly entries: Set<IBufferLineStringCacheEntry> = new Set();
+  private readonly _clearTimeout = this._register(new MutableDisposable<IDisposable>());
+  private _lastAccessTimestamp: number = 0;
+
+  constructor() {
+    super();
+    this._register(toDisposable(() => this.entries.clear()));
+  }
+
+  public touch(): void {
+    this._scheduleClear();
+  }
+
+  public allocateEntry(): IBufferLineStringCacheEntry {
+    const entry: IBufferLineStringCacheEntry = {
+      value: undefined,
+      isTrimmed: false,
+      generation: this.generation
+    };
+    this.entries.add(entry);
+    this._scheduleClear();
+    return entry;
+  }
+
+  public clear(): void {
+    this._clearTimeout.clear();
+    this._lastAccessTimestamp = 0;
+    this.generation++;
+    for (const entry of this.entries) {
+      entry.value = undefined;
+      entry.isTrimmed = false;
+    }
+    this.entries.clear();
+  }
+
+  private _scheduleClear(): void {
+    this._lastAccessTimestamp = Date.now();
+    if (this._clearTimeout.value) {
+      return;
+    }
+    this._scheduleClearTimeout(Constants.CACHE_TTL_MS);
+  }
+
+  private _scheduleClearTimeout(timeoutMs: number): void {
+    this._clearTimeout.value = disposableTimeout(() => {
+      const elapsed = Date.now() - this._lastAccessTimestamp;
+      if (elapsed >= Constants.CACHE_TTL_MS) {
+        this.clear();
+        return;
+      }
+      this._scheduleClearTimeout(Constants.CACHE_TTL_MS - elapsed);
+    }, timeoutMs);
+  }
+}

src/common/buffer/BufferReflow.test.ts

@@ -5,16 +5,18 @@
 import { assert } from 'chai';
 import { CircularList } from '../CircularList';
 import { BufferLine } from './BufferLine';
+import { BufferLineStringCache } from './BufferLineStringCache';
 import { CellData } from './CellData';
 import { NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE } from './Constants';
 import { reflowLargerGetLinesToRemove, reflowSmallerGetNewLineLengths } from './BufferReflow';
 import { IBufferLine } from './Types';
 
+const TEST_STRING_CACHE = new BufferLineStringCache();
 
 describe('BufferReflow', () => {
   describe('reflowSmallerGetNewLineLengths', () => {
     it('should return correct line lengths for a small line with wide characters', () => {
-      const line = new BufferLine(4);
+      const line = new BufferLine(TEST_STRING_CACHE, 4);
       line.set(0, [0, '汉', 2, '汉'.charCodeAt(0)]);
       line.set(1, [0, '', 0, 0]);
       line.set(2, [0, '语', 2, '语'.charCodeAt(0)]);
@@ -24,7 +26,7 @@ describe('BufferReflow', () => {
       assert.deepEqual(reflowSmallerGetNewLineLengths([line], 4, 2), [2, 2], 'line: 汉, 语');
     });
     it('should return correct line lengths for a large line with wide characters', () => {
-      const line = new BufferLine(12);
+      const line = new BufferLine(TEST_STRING_CACHE, 12);
       for (let i = 0; i < 12; i += 4) {
         line.set(i, [0, '汉', 2, '汉'.charCodeAt(0)]);
         line.set(i + 2, [0, '语', 2, '语'.charCodeAt(0)]);
@@ -46,7 +48,7 @@ describe('BufferReflow', () => {
       assert.deepEqual(reflowSmallerGetNewLineLengths([line], 12, 2), [2, 2, 2, 2, 2, 2], 'line: 汉, 语, 汉, 语, 汉, 语');
     });
     it('should return correct line lengths for a string with wide and single characters', () => {
-      const line = new BufferLine(6);
+      const line = new BufferLine(TEST_STRING_CACHE, 6);
       line.set(0, [0, 'a', 1, 'a'.charCodeAt(0)]);
       line.set(1, [0, '汉', 2, '汉'.charCodeAt(0)]);
       line.set(2, [0, '', 0, 0]);
@@ -60,14 +62,14 @@ describe('BufferReflow', () => {
       assert.deepEqual(reflowSmallerGetNewLineLengths([line], 6, 2), [1, 2, 2, 1], 'line: a, 汉, 语, b');
     });
     it('should return correct line lengths for a wrapped line with wide and single characters', () => {
-      const line1 = new BufferLine(6);
+      const line1 = new BufferLine(TEST_STRING_CACHE, 6);
       line1.set(0, [0, 'a', 1, 'a'.charCodeAt(0)]);
       line1.set(1, [0, '汉', 2, '汉'.charCodeAt(0)]);
       line1.set(2, [0, '', 0, 0]);
       line1.set(3, [0, '语', 2, '语'.charCodeAt(0)]);
       line1.set(4, [0, '', 0, 0]);
       line1.set(5, [0, 'b', 1, 'b'.charCodeAt(0)]);
-      const line2 = new BufferLine(6, undefined, true);
+      const line2 = new BufferLine(TEST_STRING_CACHE, 6, undefined, true);
       line2.set(0, [0, 'a', 1, 'a'.charCodeAt(0)]);
       line2.set(1, [0, '汉', 2, '汉'.charCodeAt(0)]);
       line2.set(2, [0, '', 0, 0]);
@@ -82,7 +84,7 @@ describe('BufferReflow', () => {
       assert.deepEqual(reflowSmallerGetNewLineLengths([line1, line2], 6, 2), [1, 2, 2, 2, 2, 2, 1], 'lines: a, 汉, 语, ba, 汉, 语, b');
     });
     it('should work on lines ending in null space', () => {
-      const line = new BufferLine(5);
+      const line = new BufferLine(TEST_STRING_CACHE, 5);
       line.set(0, [0, '汉', 2, '汉'.charCodeAt(0)]);
       line.set(1, [0, '', 0, 0]);
       line.set(2, [0, '语', 2, '语'.charCodeAt(0)]);
@@ -100,7 +102,7 @@ describe('BufferReflow', () => {
     function createWrappedLines(chars: string): CircularList<IBufferLine> {
       const lines = new CircularList<IBufferLine>(chars.length);
       for (let i = 0; i < chars.length; i++) {
-        const line = new BufferLine(1);
+        const line = new BufferLine(TEST_STRING_CACHE, 1);
         line.set(0, [0, chars[i], 1, chars.charCodeAt(i)]);
         line.isWrapped = i > 0;
         lines.push(line);

src/common/buffer/BufferSet.test.ts

@@ -82,4 +82,45 @@ describe('BufferSet', () => {
       assert.equal(bufferSet.alt.markers.length, 0);
     });
   });
+
+  describe('lifecycle', () => {
+    it('should dispose previous buffers on reset', () => {
+      const oldNormal = bufferSet.normal as any;
+      oldNormal.lines.get(0)!.setCell(0, createCellData(0, 'a', 1));
+      oldNormal.translateBufferLineToString(0, false);
+
+      const oldCache = oldNormal._stringCache;
+      assert.equal(oldCache.entries.size, 1);
+      assert.notEqual(oldCache._clearTimeout.value, undefined);
+
+      bufferSet.reset();
+
+      assert.notEqual(bufferSet.normal, oldNormal);
+      assert.equal(oldCache.entries.size, 0);
+      assert.equal(oldCache._clearTimeout.value, undefined);
+    });
+
+    it('should dispose both buffers when disposed', () => {
+      const normal = bufferSet.normal as any;
+      normal.lines.get(0)!.setCell(0, createCellData(0, 'a', 1));
+      normal.translateBufferLineToString(0, false);
+
+      bufferSet.activateAltBuffer();
+      const alt = bufferSet.alt as any;
+      alt.lines.get(0)!.setCell(0, createCellData(0, 'b', 1));
+      alt.translateBufferLineToString(0, false);
+
+      const normalCache = normal._stringCache;
+      const altCache = alt._stringCache;
+      assert.notEqual(normalCache._clearTimeout.value, undefined);
+      assert.notEqual(altCache._clearTimeout.value, undefined);
+
+      bufferSet.dispose();
+
+      assert.equal(normalCache.entries.size, 0);
+      assert.equal(altCache.entries.size, 0);
+      assert.equal(normalCache._clearTimeout.value, undefined);
+      assert.equal(altCache._clearTimeout.value, undefined);
+    });
+  });
 });

src/common/buffer/Types.ts

@@ -20,7 +20,6 @@ export interface IExtendedAttrs {
   underlineColor: number;
   underlineVariantOffset: number;
   urlId: number;
-  payload: Object | undefined;
   clone(): IExtendedAttrs;
   isEmpty(): boolean;
 }
@@ -132,8 +131,8 @@ export interface IBufferLine {
   resize(cols: number, fill: ICellData): boolean;
   cleanupMemory(): number;
   fill(fillCellData: ICellData, respectProtect?: boolean): void;
-  copyFrom(line: IBufferLine, blank?: boolean): void;
-  clone(blank?: boolean): IBufferLine;
+  copyFrom(line: IBufferLine): void;
+  clone(): IBufferLine;
   getTrimmedLength(): number;
   getNoBgTrimmedLength(): number;
   translateToString(trimRight?: boolean, startCol?: number, endCol?: number, outColumns?: number[]): string;
@@ -147,7 +146,6 @@ export interface IBufferLine {
   getCodePoint(index: number): number;
   isCombined(index: number): number;
   getString(index: number): string;
-  getExtended(index: number): IExtendedAttrs;
 }
 
 export interface IMarker extends IDisposable {

src/common/services/BufferService.ts

@@ -86,12 +86,12 @@ export class BufferService extends Disposable implements IBufferService {
       // Insert the line using the fastest method
       if (bottomRow === buffer.lines.length - 1) {
         if (willBufferBeTrimmed) {
-          buffer.lines.recycle().copyFrom(newLine, true);
+          buffer.lines.recycle().copyFrom(newLine);
         } else {
-          buffer.lines.push(newLine.clone(true));
+          buffer.lines.push(newLine.clone());
         }
       } else {
-        buffer.lines.splice(bottomRow + 1, 0, newLine.clone(true));
+        buffer.lines.splice(bottomRow + 1, 0, newLine.clone());
       }
 
       // Only adjust ybase and ydisp when the buffer is not trimmed
@@ -113,7 +113,7 @@ export class BufferService extends Disposable implements IBufferService {
       // scrollback, instead we can just shift them in-place.
       const scrollRegionHeight = bottomRow - topRow + 1 /* as it's zero-based */;
       buffer.lines.shiftElements(topRow + 1, scrollRegionHeight - 1, -1);
-      buffer.lines.set(bottomRow, newLine.clone(true));
+      buffer.lines.set(bottomRow, newLine.clone());
     }
 
     // Move the viewport to the bottom of the buffer unless the user is

src/common/services/DecorationService.ts

@@ -214,7 +214,7 @@ export class DecorationLineCache extends Disposable {
   }
 
   private _handleBufferLinesTrim(amount: number): void {
-    if (amount <= 0 || !this._decorationsByLine.size) {
+    if (amount <= 0) {
       return;
     }
     const newMap = new Map<number, IInternalDecoration[]>();

test/benchmark/BufferLine.benchmark.ts

@@ -0,0 +1,113 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { perfContext, before, RuntimeCase } from 'xterm-benchmark';
+import { BufferLine, DEFAULT_ATTR_DATA } from 'common/buffer/BufferLine';
+import { BufferLineStringCache } from 'common/buffer/BufferLineStringCache';
+import { CellData } from 'common/buffer/CellData';
+import { BgFlags, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE, UnderlineStyle } from 'common/buffer/Constants';
+
+const ITERATIONS = 500_000;
+const stringCache = new BufferLineStringCache();
+const nullCell = CellData.fromCharData([0, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE]);
+const yCell = CellData.fromCharData([0, 'y', 1, 'y'.charCodeAt(0)]);
+
+function fillPlainY(line: BufferLine, cols: number): void {
+  for (let i = 0; i < cols; i++) {
+    line.setCellFromCodepoint(i, 'y'.charCodeAt(0), 1, DEFAULT_ATTR_DATA);
+  }
+}
+
+function setupScrollRecyclePair(cols: number): { recycled: BufferLine, blank: BufferLine } {
+  const blank = new BufferLine(stringCache, cols, nullCell, false);
+  const recycled = new BufferLine(stringCache, cols, yCell, false);
+  fillPlainY(recycled, cols);
+  return { recycled, blank };
+}
+
+/** Source line with combining chars and extended attrs spread across columns. */
+function buildSparseSourceLine(cols: number): BufferLine {
+  const line = new BufferLine(stringCache, cols, nullCell, false);
+  for (let i = 0; i < cols; i++) {
+    if (i % 10 === 0) {
+      const cell = CellData.fromCharData([0, 'a', 1, 'a'.charCodeAt(0)]);
+      cell.extended.underlineStyle = UnderlineStyle.CURLY;
+      cell.bg |= BgFlags.HAS_EXTENDED;
+      line.setCell(i, cell);
+    } else if (i % 17 === 0) {
+      line.setCell(i, CellData.fromCharData([1, 'e\u0301', 1, '\u0301'.charCodeAt(0)]));
+    } else {
+      line.setCellFromCodepoint(i, 'y'.charCodeAt(0), 1, DEFAULT_ATTR_DATA);
+    }
+  }
+  return line;
+}
+
+function setupCopyFromSparsePair(cols: number): { dest: BufferLine, src: BufferLine } {
+  const src = buildSparseSourceLine(cols);
+  const dest = new BufferLine(stringCache, cols, yCell, false);
+  fillPlainY(dest, cols);
+  return { dest, src };
+}
+
+perfContext('BufferLine.copyFrom (scroll recycle)', () => {
+  perfContext('cols=80', () => {
+    let recycled: BufferLine;
+    let blank: BufferLine;
+    before(() => {
+      ({ recycled, blank } = setupScrollRecyclePair(80));
+    });
+    new RuntimeCase('', () => {
+      for (let i = 0; i < ITERATIONS; i++) {
+        recycled.copyFrom(blank);
+      }
+      return { payloadSize: ITERATIONS };
+    }, { fork: false }).showAverageRuntime();
+  });
+
+  perfContext('cols=279', () => {
+    let recycled: BufferLine;
+    let blank: BufferLine;
+    before(() => {
+      ({ recycled, blank } = setupScrollRecyclePair(279));
+    });
+    new RuntimeCase('', () => {
+      for (let i = 0; i < ITERATIONS; i++) {
+        recycled.copyFrom(blank);
+      }
+      return { payloadSize: ITERATIONS };
+    }, { fork: false }).showAverageRuntime();
+  });
+});
+
+perfContext('BufferLine.copyFrom (sparse source: combined + extended attrs)', () => {
+  perfContext('cols=80', () => {
+    let dest: BufferLine;
+    let src: BufferLine;
+    before(() => {
+      ({ dest, src } = setupCopyFromSparsePair(80));
+    });
+    new RuntimeCase('', () => {
+      for (let i = 0; i < ITERATIONS; i++) {
+        dest.copyFrom(src);
+      }
+      return { payloadSize: ITERATIONS };
+    }, { fork: false }).showAverageRuntime();
+  });
+
+  perfContext('cols=279', () => {
+    let dest: BufferLine;
+    let src: BufferLine;
+    before(() => {
+      ({ dest, src } = setupCopyFromSparsePair(279));
+    });
+    new RuntimeCase('', () => {
+      for (let i = 0; i < ITERATIONS; i++) {
+        dest.copyFrom(src);
+      }
+      return { payloadSize: ITERATIONS };
+    }, { fork: false }).showAverageRuntime();
+  });
+});