From 9c3eb170d2369b5d0d0e9bb83afb6ee33e27636f Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Mon, 21 Jul 2025 23:07:47 +0000
Subject: [PATCH 01/22] Bump form-data from 4.0.0 to 4.0.4 in
 /addons/addon-ligatures

Bumps [form-data](https://github.com/form-data/form-data) from 4.0.0 to 4.0.4.
- [Release notes](https://github.com/form-data/form-data/releases)
- [Changelog](https://github.com/form-data/form-data/blob/master/CHANGELOG.md)
- [Commits](https://github.com/form-data/form-data/compare/v4.0.0...v4.0.4)

---
updated-dependencies:
- dependency-name: form-data
  dependency-version: 4.0.4
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
---
 addons/addon-ligatures/yarn.lock | 110 ++++++++++++++++++++++++++++++-
 1 file changed, 107 insertions(+), 3 deletions(-)

diff --git a/addons/addon-ligatures/yarn.lock b/addons/addon-ligatures/yarn.lock
index 9608e035..2c910bca 100644
--- a/addons/addon-ligatures/yarn.lock
+++ b/addons/addon-ligatures/yarn.lock
@@ -63,6 +63,14 @@ buffer-crc32@~0.2.3:
   version "0.2.13"
   resolved "https://registry.yarnpkg.com/buffer-crc32/-/buffer-crc32-0.2.13.tgz#0d333e3f00eac50aa1454abd30ef8c2a5d9a7242"
 
+call-bind-apply-helpers@^1.0.1, call-bind-apply-helpers@^1.0.2:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/call-bind-apply-helpers/-/call-bind-apply-helpers-1.0.2.tgz#4b5428c222be985d79c3d82657479dbe0b59b2d6"
+  integrity sha512-Sp1ablJ0ivDkSzjcaJdxEunN5/XvksFJ2sMBFfq6x0ryhQV/2b/KwFe21cMpmHtPOSij8K99/wSfoEuTObmuMQ==
+  dependencies:
+    es-errors "^1.3.0"
+    function-bind "^1.1.2"
+
 combined-stream@^1.0.8:
   version "1.0.8"
   resolved "https://registry.yarnpkg.com/combined-stream/-/combined-stream-1.0.8.tgz#c3d45a8b34fd730631a110a8a2520682b31d5a7f"
@@ -79,6 +87,42 @@ diff@^3.5.0:
   version "3.5.0"
   resolved "https://registry.yarnpkg.com/diff/-/diff-3.5.0.tgz#800c0dd1e0a8bfbc95835c202ad220fe317e5a12"
 
+dunder-proto@^1.0.1:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/dunder-proto/-/dunder-proto-1.0.1.tgz#d7ae667e1dc83482f8b70fd0f6eefc50da30f58a"
+  integrity sha512-KIN/nDJBQRcXw0MLVhZE9iQHmG68qAVIBg9CqmUYjmQIhgij9U5MFvrqkUL5FbtyyzZuOeOt0zdeRe4UY7ct+A==
+  dependencies:
+    call-bind-apply-helpers "^1.0.1"
+    es-errors "^1.3.0"
+    gopd "^1.2.0"
+
+es-define-property@^1.0.1:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/es-define-property/-/es-define-property-1.0.1.tgz#983eb2f9a6724e9303f61addf011c72e09e0b0fa"
+  integrity sha512-e3nRfgfUZ4rNGL232gUgX06QNyyez04KdjFrF+LTRoOXmrOgFKDg4BCdsjW8EnT69eqdYGmRpJwiPVYNrCaW3g==
+
+es-errors@^1.3.0:
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/es-errors/-/es-errors-1.3.0.tgz#05f75a25dab98e4fb1dcd5e1472c0546d5057c8f"
+  integrity sha512-Zf5H2Kxt2xjTvbJvP2ZWLEICxA6j+hAmMzIlypy4xcBg1vKVnx89Wy0GbS+kf5cwCVFFzdCFh2XSCFNULS6csw==
+
+es-object-atoms@^1.0.0, es-object-atoms@^1.1.1:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/es-object-atoms/-/es-object-atoms-1.1.1.tgz#1c4f2c4837327597ce69d2ca190a7fdd172338c1"
+  integrity sha512-FGgH2h8zKNim9ljj7dankFPcICIK9Cp5bm+c2gQSYePhpaG5+esrLODihIorn+Pe6FGJzWhXQotPv73jTaldXA==
+  dependencies:
+    es-errors "^1.3.0"
+
+es-set-tostringtag@^2.1.0:
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/es-set-tostringtag/-/es-set-tostringtag-2.1.0.tgz#f31dbbe0c183b00a6d26eb6325c810c0fd18bd4d"
+  integrity sha512-j6vWzfrGVfyXxge+O0x5sh6cvxAog0a/4Rdd2K36zCMV5eJ+/+tOAngRO8cODMNWbVRdVlmGZQL2YS3yR8bIUA==
+  dependencies:
+    es-errors "^1.3.0"
+    get-intrinsic "^1.2.6"
+    has-tostringtag "^1.0.2"
+    hasown "^2.0.2"
+
 fd-slicer@~1.1.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/fd-slicer/-/fd-slicer-1.1.0.tgz#25c7c89cb1f9077f8891bbe61d8f390eae256f1e"
@@ -115,22 +159,77 @@ font-ligatures@^1.4.1:
     opentype.js "^0.8.0"
 
 form-data@^4.0.0:
-  version "4.0.0"
-  resolved "https://registry.yarnpkg.com/form-data/-/form-data-4.0.0.tgz#93919daeaf361ee529584b9b31664dc12c9fa452"
-  integrity sha512-ETEklSGi5t0QMZuiXoA/Q6vcnxcLQP5vdugSpuAyi6SVGi2clPPp+xgEhuMaHC+zGgn31Kd235W35f7Hykkaww==
+  version "4.0.4"
+  resolved "https://registry.yarnpkg.com/form-data/-/form-data-4.0.4.tgz#784cdcce0669a9d68e94d11ac4eea98088edd2c4"
+  integrity sha512-KrGhL9Q4zjj0kiUt5OO4Mr/A/jlI2jDYs5eHBpYHPcBEVSiipAvn2Ko2HnPe20rmcuuvMHNdZFp+4IlGTMF0Ow==
   dependencies:
     asynckit "^0.4.0"
     combined-stream "^1.0.8"
+    es-set-tostringtag "^2.1.0"
+    hasown "^2.0.2"
     mime-types "^2.1.12"
 
+function-bind@^1.1.2:
+  version "1.1.2"
+  resolved "https://registry.yarnpkg.com/function-bind/-/function-bind-1.1.2.tgz#2c02d864d97f3ea6c8830c464cbd11ab6eab7a1c"
+  integrity sha512-7XHNxH7qX9xG5mIwxkhumTox/MIRNcOgDrxWsMt2pAr23WHp6MrRlN7FBSFpCpr+oVO0F744iUgR82nJMfG2SA==
+
+get-intrinsic@^1.2.6:
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/get-intrinsic/-/get-intrinsic-1.3.0.tgz#743f0e3b6964a93a5491ed1bffaae054d7f98d01"
+  integrity sha512-9fSjSaos/fRIVIp+xSJlE6lfwhES7LNtKaCBIamHsjr2na1BiABJPo0mOjjz8GJDURarmCPGqaiVg5mfjb98CQ==
+  dependencies:
+    call-bind-apply-helpers "^1.0.2"
+    es-define-property "^1.0.1"
+    es-errors "^1.3.0"
+    es-object-atoms "^1.1.1"
+    function-bind "^1.1.2"
+    get-proto "^1.0.1"
+    gopd "^1.2.0"
+    has-symbols "^1.1.0"
+    hasown "^2.0.2"
+    math-intrinsics "^1.1.0"
+
+get-proto@^1.0.1:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/get-proto/-/get-proto-1.0.1.tgz#150b3f2743869ef3e851ec0c49d15b1d14d00ee1"
+  integrity sha512-sTSfBjoXBp89JvIKIefqw7U2CCebsc74kiY6awiGogKtoSGbgjYE/G/+l9sF3MWFPNc9IcoOC4ODfKHfxFmp0g==
+  dependencies:
+    dunder-proto "^1.0.1"
+    es-object-atoms "^1.0.0"
+
 get-system-fonts@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/get-system-fonts/-/get-system-fonts-2.0.0.tgz#a43b9a33f05c0715a60176d2aad5ce6e98f0a3c6"
 
+gopd@^1.2.0:
+  version "1.2.0"
+  resolved "https://registry.yarnpkg.com/gopd/-/gopd-1.2.0.tgz#89f56b8217bdbc8802bd299df6d7f1081d7e51a1"
+  integrity sha512-ZUKRh6/kUFoAiTAtTYPZJ3hw9wNxx+BIBOijnlG9PnrJsCcSjs1wyyD6vJpaYtgnzDrKYRSqf3OO6Rfa93xsRg==
+
 has-flag@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/has-flag/-/has-flag-3.0.0.tgz#b5d454dc2199ae225699f3467e5a07f3b955bafd"
 
+has-symbols@^1.0.3, has-symbols@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/has-symbols/-/has-symbols-1.1.0.tgz#fc9c6a783a084951d0b971fe1018de813707a338"
+  integrity sha512-1cDNdwJ2Jaohmb3sg4OmKaMBwuC48sYni5HUw2DvsC8LjGTLK9h+eb1X6RyuOHe4hT0ULCW68iomhjUoKUqlPQ==
+
+has-tostringtag@^1.0.2:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/has-tostringtag/-/has-tostringtag-1.0.2.tgz#2cdc42d40bef2e5b4eeab7c01a73c54ce7ab5abc"
+  integrity sha512-NqADB8VjPFLM2V0VvHUewwwsw0ZWBaIdgo+ieHtK3hasLz4qeCRjYcqfB6AQrBggRKppKF8L52/VqdVsO47Dlw==
+  dependencies:
+    has-symbols "^1.0.3"
+
+hasown@^2.0.2:
+  version "2.0.2"
+  resolved "https://registry.yarnpkg.com/hasown/-/hasown-2.0.2.tgz#003eaf91be7adc372e84ec59dc37252cedb80003"
+  integrity sha512-0hJU9SCPvmMzIBdZFqNPXWa6dqh7WdH0cII9y+CyS8rG3nL48Bclra9HmKhVVUHyPWNH5Y7xDwAB7bfgSjkUMQ==
+  dependencies:
+    function-bind "^1.1.2"
+
 isarray@0.0.1:
   version "0.0.1"
   resolved "https://registry.yarnpkg.com/isarray/-/isarray-0.0.1.tgz#8a18acfca9a8f4177e09abfc6038939b05d1eedf"
@@ -168,6 +267,11 @@ lru-cache@^6.0.0:
   dependencies:
     yallist "^4.0.0"
 
+math-intrinsics@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/math-intrinsics/-/math-intrinsics-1.1.0.tgz#a0dd74be81e2aa5c2f27e65ce283605ee4e2b7f9"
+  integrity sha512-/IXtbwEk5HTPyEwyKX6hGkYXxM9nbj64B+ilVJnC/R6B0pH5G4V3b0pVbL7DBj4tkhBAppbQUlf6F6Xl9LHu1g==
+
 mime-db@1.52.0:
   version "1.52.0"
   resolved "https://registry.yarnpkg.com/mime-db/-/mime-db-1.52.0.tgz#bbabcdc02859f4987301c856e3387ce5ec43bf70"

From a3ab942ea157c1981847f1467be7f5379f14e6c0 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Wed, 27 Aug 2025 20:45:52 -0700
Subject: [PATCH 02/22] Fix teleport issue when coming back from alt buffer

---
 src/common/TestUtils.test.ts         | 3 +++
 src/common/buffer/BufferSet.ts       | 2 ++
 src/common/services/BufferService.ts | 7 +++++++
 src/common/services/Services.ts      | 1 +
 4 files changed, 13 insertions(+)

diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index 127e1f24..ccdb54ae 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -46,6 +46,9 @@ export class MockBufferService implements IBufferService {
   public scrollLines(disp: number, suppressScrollEvent?: boolean): void {
     throw new Error('Method not implemented.');
   }
+  public syncScrollPosition(): void {
+    // Mock implementation - no-op for tests
+  }
   public resize(cols: number, rows: number): void {
     this.cols = cols;
     this.rows = rows;
diff --git a/src/common/buffer/BufferSet.ts b/src/common/buffer/BufferSet.ts
index 8f3a6aec..54390f2a 100644
--- a/src/common/buffer/BufferSet.ts
+++ b/src/common/buffer/BufferSet.ts
@@ -91,6 +91,8 @@ export class BufferSet extends Disposable implements IBufferSet {
       activeBuffer: this._normal,
       inactiveBuffer: this._alt
     });
+    // Prevent scrollbar "teleport" to top of the terminal, from previous alt buffer.
+    this._bufferService.syncScrollPosition();
   }
 
   /**
diff --git a/src/common/services/BufferService.ts b/src/common/services/BufferService.ts
index c4698e68..85699f6f 100644
--- a/src/common/services/BufferService.ts
+++ b/src/common/services/BufferService.ts
@@ -148,4 +148,11 @@ export class BufferService extends Disposable implements IBufferService {
       this._onScroll.fire(buffer.ydisp);
     }
   }
+
+  /**
+   * Synchronize the scroll position by firing a scroll event with the current buffer's ydisp.
+   */
+  public syncScrollPosition(): void {
+    this._onScroll.fire(this.buffer.ydisp);
+  }
 }
diff --git a/src/common/services/Services.ts b/src/common/services/Services.ts
index 9c3aebf7..58ee113f 100644
--- a/src/common/services/Services.ts
+++ b/src/common/services/Services.ts
@@ -22,6 +22,7 @@ export interface IBufferService {
   onScroll: Event<number>;
   scroll(eraseAttr: IAttributeData, isWrapped?: boolean): void;
   scrollLines(disp: number, suppressScrollEvent?: boolean): void;
+  syncScrollPosition(): void;
   resize(cols: number, rows: number): void;
   reset(): void;
 }

From 86745e1320f95b0c4f71330acc2d6a56ed0344a4 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Wed, 27 Aug 2025 21:12:15 -0700
Subject: [PATCH 03/22] Add some tests from copilot

---
 src/common/buffer/BufferSet.test.ts | 67 +++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/src/common/buffer/BufferSet.test.ts b/src/common/buffer/BufferSet.test.ts
index 944b8c15..4c937729 100644
--- a/src/common/buffer/BufferSet.test.ts
+++ b/src/common/buffer/BufferSet.test.ts
@@ -7,6 +7,7 @@ import { assert } from 'chai';
 import { BufferSet } from 'common/buffer/BufferSet';
 import { Buffer } from 'common/buffer/Buffer';
 import { MockOptionsService, MockBufferService } from 'common/TestUtils.test';
+import { Emitter } from 'vs/base/common/event';
 
 describe('BufferSet', () => {
   let bufferSet: BufferSet;
@@ -81,4 +82,70 @@ describe('BufferSet', () => {
       assert.equal(bufferSet.alt.markers.length, 0);
     });
   });
+
+  describe('scroll position synchronization', () => {
+    it('should sync scroll position when switching from alt back to normal buffer', () => {
+      bufferSet.activateNormalBuffer();
+
+      const originalYDisp = 50;
+      bufferSet.normal.ydisp = originalYDisp;
+      bufferSet.normal.ybase = 100;
+
+      // Track onScroll events fired by the buffer service
+      let scrollEventFired = false;
+      let scrollEventPosition = -1;
+
+      const mockBufferService = (bufferSet as any)._bufferService as MockBufferService;
+      const originalOnScroll = mockBufferService.onScroll;
+
+      // Mock the onScroll event to track when it's called
+      const scrollEmitter = new Emitter<number>();
+      mockBufferService.onScroll = scrollEmitter.event;
+
+      // Override syncScrollPosition to actually fire the event
+      mockBufferService.syncScrollPosition = () => {
+        scrollEventFired = true;
+        scrollEventPosition = bufferSet.normal.ydisp;
+        scrollEmitter.fire(bufferSet.normal.ydisp);
+      };
+
+
+      bufferSet.activateAltBuffer();
+      assert.equal(bufferSet.normal.ydisp, originalYDisp, 'Normal buffer ydisp should be preserved');
+
+      // Reset scroll event tracking
+      scrollEventFired = false;
+      scrollEventPosition = -1;
+
+      bufferSet.activateNormalBuffer();
+      assert.equal(bufferSet.normal.ydisp, originalYDisp, 'Normal buffer ydisp should be restored');
+      assert.equal(scrollEventFired, true, 'syncScrollPosition should have fired scroll event');
+      assert.equal(scrollEventPosition, originalYDisp, 'Scroll event should contain correct position');
+      assert.equal(bufferSet.active, bufferSet.normal, 'Normal buffer should be active');
+    });
+
+    it('should preserve normal buffer scroll position even when alt buffer has different position', () => {
+      bufferSet.activateNormalBuffer();
+      const normalScrollPos = 80;
+      bufferSet.normal.ydisp = normalScrollPos;
+      bufferSet.normal.ybase = 150;
+
+      bufferSet.activateAltBuffer();
+      bufferSet.alt.ydisp = 0;
+      bufferSet.alt.ybase = 0;
+
+      const mockBufferService = (bufferSet as any)._bufferService as MockBufferService;
+      let syncedPosition = -1;
+
+      // Track the position that gets synced
+      mockBufferService.syncScrollPosition = () => {
+        syncedPosition = bufferSet.normal.ydisp;
+      };
+
+      bufferSet.activateNormalBuffer();
+      assert.equal(bufferSet.normal.ydisp, normalScrollPos, 'Normal buffer should maintain its scroll position');
+      assert.equal(syncedPosition, normalScrollPos, 'syncScrollPosition should sync with normal buffer position');
+      assert.notEqual(syncedPosition, bufferSet.alt.ydisp, 'Sync position should not match alt buffer position');
+    });
+  });
 });

From 675b2c3a70844d4a2a655a6e54a38125000498cc Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Wed, 27 Aug 2025 21:31:34 -0700
Subject: [PATCH 04/22] Improve test

---
 src/common/TestUtils.test.ts        |  9 ++--
 src/common/buffer/BufferSet.test.ts | 65 ++++++++++++++---------------
 2 files changed, 38 insertions(+), 36 deletions(-)

diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index ccdb54ae..041481b5 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -18,8 +18,10 @@ export class MockBufferService implements IBufferService {
   public serviceBrand: any;
   public get buffer(): IBuffer { return this.buffers.active; }
   public buffers: IBufferSet = {} as any;
-  public onResize: Event<{ cols: number, rows: number }> = new Emitter<{ cols: number, rows: number }>().event;
-  public onScroll: Event<number> = new Emitter<number>().event;
+  private readonly _onResize = new Emitter<{ cols: number, rows: number }>();
+  public readonly onResize: Event<{ cols: number, rows: number }> = this._onResize.event;
+  private readonly _onScroll = new Emitter<number>();
+  public readonly onScroll: Event<number> = this._onScroll.event;
   public isUserScrolling: boolean = false;
   constructor(
     public cols: number,
@@ -47,7 +49,8 @@ export class MockBufferService implements IBufferService {
     throw new Error('Method not implemented.');
   }
   public syncScrollPosition(): void {
-    // Mock implementation - no-op for tests
+    // Fire scroll event with current buffer position
+    this._onScroll.fire(this.buffer.ydisp);
   }
   public resize(cols: number, rows: number): void {
     this.cols = cols;
diff --git a/src/common/buffer/BufferSet.test.ts b/src/common/buffer/BufferSet.test.ts
index 4c937729..449c40b8 100644
--- a/src/common/buffer/BufferSet.test.ts
+++ b/src/common/buffer/BufferSet.test.ts
@@ -84,47 +84,32 @@ describe('BufferSet', () => {
   });
 
   describe('scroll position synchronization', () => {
-    it('should sync scroll position when switching from alt back to normal buffer', () => {
+    it('should call syncScrollPosition when switching from alt back to normal buffer', () => {
       bufferSet.activateNormalBuffer();
 
       const originalYDisp = 50;
       bufferSet.normal.ydisp = originalYDisp;
       bufferSet.normal.ybase = 100;
-
-      // Track onScroll events fired by the buffer service
-      let scrollEventFired = false;
-      let scrollEventPosition = -1;
-
       const mockBufferService = (bufferSet as any)._bufferService as MockBufferService;
-      const originalOnScroll = mockBufferService.onScroll;
 
-      // Mock the onScroll event to track when it's called
-      const scrollEmitter = new Emitter<number>();
-      mockBufferService.onScroll = scrollEmitter.event;
-
-      // Override syncScrollPosition to actually fire the event
+      let syncScrollPositionCalled = false;
+      const originalSyncScrollPosition = mockBufferService.syncScrollPosition.bind(mockBufferService);
       mockBufferService.syncScrollPosition = () => {
-        scrollEventFired = true;
-        scrollEventPosition = bufferSet.normal.ydisp;
-        scrollEmitter.fire(bufferSet.normal.ydisp);
+        syncScrollPositionCalled = true;
+        originalSyncScrollPosition();
       };
 
-
       bufferSet.activateAltBuffer();
       assert.equal(bufferSet.normal.ydisp, originalYDisp, 'Normal buffer ydisp should be preserved');
-
-      // Reset scroll event tracking
-      scrollEventFired = false;
-      scrollEventPosition = -1;
-
+      syncScrollPositionCalled = false;
       bufferSet.activateNormalBuffer();
+
       assert.equal(bufferSet.normal.ydisp, originalYDisp, 'Normal buffer ydisp should be restored');
-      assert.equal(scrollEventFired, true, 'syncScrollPosition should have fired scroll event');
-      assert.equal(scrollEventPosition, originalYDisp, 'Scroll event should contain correct position');
+      assert.equal(syncScrollPositionCalled, true, 'activateNormalBuffer should call syncScrollPosition');
       assert.equal(bufferSet.active, bufferSet.normal, 'Normal buffer should be active');
     });
 
-    it('should preserve normal buffer scroll position even when alt buffer has different position', () => {
+    it('should preserve normal buffer scroll position when switching back from alt buffer', () => {
       bufferSet.activateNormalBuffer();
       const normalScrollPos = 80;
       bufferSet.normal.ydisp = normalScrollPos;
@@ -133,19 +118,33 @@ describe('BufferSet', () => {
       bufferSet.activateAltBuffer();
       bufferSet.alt.ydisp = 0;
       bufferSet.alt.ybase = 0;
+      bufferSet.activateNormalBuffer();
 
+      assert.equal(bufferSet.normal.ydisp, normalScrollPos, 'Normal buffer should maintain its scroll position');
+      assert.equal(bufferSet.active, bufferSet.normal, 'Normal buffer should be active');
+      assert.notEqual(bufferSet.normal.ydisp, bufferSet.alt.ydisp, 'Normal and alt buffer should have different scroll positions');
+    });
+
+    it('should fire scroll event with correct position when syncScrollPosition is called', () => {
       const mockBufferService = (bufferSet as any)._bufferService as MockBufferService;
-      let syncedPosition = -1;
-
-      // Track the position that gets synced
-      mockBufferService.syncScrollPosition = () => {
-        syncedPosition = bufferSet.normal.ydisp;
-      };
 
       bufferSet.activateNormalBuffer();
-      assert.equal(bufferSet.normal.ydisp, normalScrollPos, 'Normal buffer should maintain its scroll position');
-      assert.equal(syncedPosition, normalScrollPos, 'syncScrollPosition should sync with normal buffer position');
-      assert.notEqual(syncedPosition, bufferSet.alt.ydisp, 'Sync position should not match alt buffer position');
+      const testScrollPosition = 42;
+
+      mockBufferService.buffer.ydisp = testScrollPosition;
+      assert.equal(mockBufferService.buffer.ydisp, testScrollPosition, 'Active buffer ydisp should be set correctly');
+
+      let scrollEventFired = false;
+      let scrollEventPosition = -1;
+
+      mockBufferService.onScroll((position: number) => {
+        scrollEventFired = true;
+        scrollEventPosition = position;
+      });
+
+      mockBufferService.syncScrollPosition();
+      assert.equal(scrollEventFired, true, 'syncScrollPosition should fire scroll event');
+      assert.equal(scrollEventPosition, testScrollPosition, `Scroll event should contain current buffer ydisp`);
     });
   });
 });

From 753ea81fc08661b4c661338461c81b3a06178d8c Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Thu, 28 Aug 2025 08:46:27 -0700
Subject: [PATCH 05/22] BufferService listen to onBufferActivate, remove tests

---
 src/common/TestUtils.test.ts         |  8 ++--
 src/common/buffer/BufferSet.test.ts  | 64 ----------------------------
 src/common/buffer/BufferSet.ts       |  2 -
 src/common/services/BufferService.ts |  9 ++--
 src/common/services/Services.ts      |  1 -
 5 files changed, 7 insertions(+), 77 deletions(-)

diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index 041481b5..d9d3b24e 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -29,6 +29,10 @@ export class MockBufferService implements IBufferService {
     optionsService: IOptionsService = new MockOptionsService()
   ) {
     this.buffers = new BufferSet(optionsService, this);
+    // Listen to buffer activation events and automatically fire scroll events
+    this.buffers.onBufferActivate(e => {
+      this._onScroll.fire(e.activeBuffer.ydisp);
+    });
   }
   public scrollPages(pageCount: number): void {
     throw new Error('Method not implemented.');
@@ -48,10 +52,6 @@ export class MockBufferService implements IBufferService {
   public scrollLines(disp: number, suppressScrollEvent?: boolean): void {
     throw new Error('Method not implemented.');
   }
-  public syncScrollPosition(): void {
-    // Fire scroll event with current buffer position
-    this._onScroll.fire(this.buffer.ydisp);
-  }
   public resize(cols: number, rows: number): void {
     this.cols = cols;
     this.rows = rows;
diff --git a/src/common/buffer/BufferSet.test.ts b/src/common/buffer/BufferSet.test.ts
index 449c40b8..b6136094 100644
--- a/src/common/buffer/BufferSet.test.ts
+++ b/src/common/buffer/BufferSet.test.ts
@@ -83,68 +83,4 @@ describe('BufferSet', () => {
     });
   });
 
-  describe('scroll position synchronization', () => {
-    it('should call syncScrollPosition when switching from alt back to normal buffer', () => {
-      bufferSet.activateNormalBuffer();
-
-      const originalYDisp = 50;
-      bufferSet.normal.ydisp = originalYDisp;
-      bufferSet.normal.ybase = 100;
-      const mockBufferService = (bufferSet as any)._bufferService as MockBufferService;
-
-      let syncScrollPositionCalled = false;
-      const originalSyncScrollPosition = mockBufferService.syncScrollPosition.bind(mockBufferService);
-      mockBufferService.syncScrollPosition = () => {
-        syncScrollPositionCalled = true;
-        originalSyncScrollPosition();
-      };
-
-      bufferSet.activateAltBuffer();
-      assert.equal(bufferSet.normal.ydisp, originalYDisp, 'Normal buffer ydisp should be preserved');
-      syncScrollPositionCalled = false;
-      bufferSet.activateNormalBuffer();
-
-      assert.equal(bufferSet.normal.ydisp, originalYDisp, 'Normal buffer ydisp should be restored');
-      assert.equal(syncScrollPositionCalled, true, 'activateNormalBuffer should call syncScrollPosition');
-      assert.equal(bufferSet.active, bufferSet.normal, 'Normal buffer should be active');
-    });
-
-    it('should preserve normal buffer scroll position when switching back from alt buffer', () => {
-      bufferSet.activateNormalBuffer();
-      const normalScrollPos = 80;
-      bufferSet.normal.ydisp = normalScrollPos;
-      bufferSet.normal.ybase = 150;
-
-      bufferSet.activateAltBuffer();
-      bufferSet.alt.ydisp = 0;
-      bufferSet.alt.ybase = 0;
-      bufferSet.activateNormalBuffer();
-
-      assert.equal(bufferSet.normal.ydisp, normalScrollPos, 'Normal buffer should maintain its scroll position');
-      assert.equal(bufferSet.active, bufferSet.normal, 'Normal buffer should be active');
-      assert.notEqual(bufferSet.normal.ydisp, bufferSet.alt.ydisp, 'Normal and alt buffer should have different scroll positions');
-    });
-
-    it('should fire scroll event with correct position when syncScrollPosition is called', () => {
-      const mockBufferService = (bufferSet as any)._bufferService as MockBufferService;
-
-      bufferSet.activateNormalBuffer();
-      const testScrollPosition = 42;
-
-      mockBufferService.buffer.ydisp = testScrollPosition;
-      assert.equal(mockBufferService.buffer.ydisp, testScrollPosition, 'Active buffer ydisp should be set correctly');
-
-      let scrollEventFired = false;
-      let scrollEventPosition = -1;
-
-      mockBufferService.onScroll((position: number) => {
-        scrollEventFired = true;
-        scrollEventPosition = position;
-      });
-
-      mockBufferService.syncScrollPosition();
-      assert.equal(scrollEventFired, true, 'syncScrollPosition should fire scroll event');
-      assert.equal(scrollEventPosition, testScrollPosition, `Scroll event should contain current buffer ydisp`);
-    });
-  });
 });
diff --git a/src/common/buffer/BufferSet.ts b/src/common/buffer/BufferSet.ts
index 54390f2a..8f3a6aec 100644
--- a/src/common/buffer/BufferSet.ts
+++ b/src/common/buffer/BufferSet.ts
@@ -91,8 +91,6 @@ export class BufferSet extends Disposable implements IBufferSet {
       activeBuffer: this._normal,
       inactiveBuffer: this._alt
     });
-    // Prevent scrollbar "teleport" to top of the terminal, from previous alt buffer.
-    this._bufferService.syncScrollPosition();
   }
 
   /**
diff --git a/src/common/services/BufferService.ts b/src/common/services/BufferService.ts
index 85699f6f..616e5619 100644
--- a/src/common/services/BufferService.ts
+++ b/src/common/services/BufferService.ts
@@ -37,6 +37,9 @@ export class BufferService extends Disposable implements IBufferService {
     this.cols = Math.max(optionsService.rawOptions.cols || 0, MINIMUM_COLS);
     this.rows = Math.max(optionsService.rawOptions.rows || 0, MINIMUM_ROWS);
     this.buffers = this._register(new BufferSet(optionsService, this));
+    this._register(this.buffers.onBufferActivate(e => {
+      this._onScroll.fire(e.activeBuffer.ydisp);
+    }));
   }
 
   public resize(cols: number, rows: number): void {
@@ -149,10 +152,4 @@ export class BufferService extends Disposable implements IBufferService {
     }
   }
 
-  /**
-   * Synchronize the scroll position by firing a scroll event with the current buffer's ydisp.
-   */
-  public syncScrollPosition(): void {
-    this._onScroll.fire(this.buffer.ydisp);
-  }
 }
diff --git a/src/common/services/Services.ts b/src/common/services/Services.ts
index 58ee113f..9c3aebf7 100644
--- a/src/common/services/Services.ts
+++ b/src/common/services/Services.ts
@@ -22,7 +22,6 @@ export interface IBufferService {
   onScroll: Event<number>;
   scroll(eraseAttr: IAttributeData, isWrapped?: boolean): void;
   scrollLines(disp: number, suppressScrollEvent?: boolean): void;
-  syncScrollPosition(): void;
   resize(cols: number, rows: number): void;
   reset(): void;
 }

From 4d59eca5f9171e67a3e4d4daf28242746e6d7b28 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Thu, 28 Aug 2025 08:52:46 -0700
Subject: [PATCH 06/22] Clean up

---
 src/common/buffer/BufferSet.test.ts | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/common/buffer/BufferSet.test.ts b/src/common/buffer/BufferSet.test.ts
index b6136094..944b8c15 100644
--- a/src/common/buffer/BufferSet.test.ts
+++ b/src/common/buffer/BufferSet.test.ts
@@ -7,7 +7,6 @@ import { assert } from 'chai';
 import { BufferSet } from 'common/buffer/BufferSet';
 import { Buffer } from 'common/buffer/Buffer';
 import { MockOptionsService, MockBufferService } from 'common/TestUtils.test';
-import { Emitter } from 'vs/base/common/event';
 
 describe('BufferSet', () => {
   let bufferSet: BufferSet;
@@ -82,5 +81,4 @@ describe('BufferSet', () => {
       assert.equal(bufferSet.alt.markers.length, 0);
     });
   });
-
 });

From 287702610c81ab346202aa53494847ed2addbfdd Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Thu, 28 Aug 2025 08:54:01 -0700
Subject: [PATCH 07/22] More clean up after removing test

---
 src/common/TestUtils.test.ts | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index d9d3b24e..f504cbe9 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -18,10 +18,9 @@ export class MockBufferService implements IBufferService {
   public serviceBrand: any;
   public get buffer(): IBuffer { return this.buffers.active; }
   public buffers: IBufferSet = {} as any;
-  private readonly _onResize = new Emitter<{ cols: number, rows: number }>();
-  public readonly onResize: Event<{ cols: number, rows: number }> = this._onResize.event;
+  public onResize: Event<{ cols: number, rows: number }> = new Emitter<{ cols: number, rows: number }>().event;
+  public onScroll: Event<number> = new Emitter<number>().event;
   private readonly _onScroll = new Emitter<number>();
-  public readonly onScroll: Event<number> = this._onScroll.event;
   public isUserScrolling: boolean = false;
   constructor(
     public cols: number,

From a6fdf043cedc1a09fefd675cb7246314ff2c9138 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Thu, 28 Aug 2025 08:57:25 -0700
Subject: [PATCH 08/22] Respect original formatting

---
 src/common/services/BufferService.ts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/common/services/BufferService.ts b/src/common/services/BufferService.ts
index 616e5619..d8d8d6b6 100644
--- a/src/common/services/BufferService.ts
+++ b/src/common/services/BufferService.ts
@@ -151,5 +151,4 @@ export class BufferService extends Disposable implements IBufferService {
       this._onScroll.fire(buffer.ydisp);
     }
   }
-
 }

From 5bd7b4aaecc10caacec50dc481ec5ac19b1f0cce Mon Sep 17 00:00:00 2001
From: Daniel Imms <2193314+Tyriar@users.noreply.github.com>
Date: Thu, 28 Aug 2025 10:28:19 -0700
Subject: [PATCH 09/22] Bring back partial wheel tracking

Part of microsoft/vscode#224750
---
 src/browser/CoreBrowserTerminal.ts | 41 ++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/src/browser/CoreBrowserTerminal.ts b/src/browser/CoreBrowserTerminal.ts
index 14ff9433..37b33f7e 100644
--- a/src/browser/CoreBrowserTerminal.ts
+++ b/src/browser/CoreBrowserTerminal.ts
@@ -646,6 +646,10 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           if (deltaY === 0) {
             return false;
           }
+          const lines = self._consumeWheelEvent(ev as WheelEvent);
+          if (lines === 0) {
+            return false;
+          }
           action = deltaY < 0 ? CoreMouseAction.UP : CoreMouseAction.DOWN;
           but = CoreMouseButton.WHEEL;
           break;
@@ -817,6 +821,11 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           return false;
         }
 
+        const lines = self._consumeWheelEvent(ev as WheelEvent);
+        if (lines === 0) {
+          return false;
+        }
+
         // Construct and send sequences
         const sequence = C0.ESC + (this.coreService.decPrivateModes.applicationCursorKeys ? 'O' : '[') + (ev.deltaY < 0 ? 'A' : 'B');
         this.coreService.triggerDataEvent(sequence, true);
@@ -825,6 +834,38 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
     }, { passive: false }));
   }
 
+  // Stores a partial line amount when scrolling, this is used to keep track of how much of a line
+  // is scrolled so we can "scroll" over partial lines and feel natural on touchpads. This is a
+  // quick fix and could have a more robust solution in place that reset the value when needed.
+  private _wheelPartialScroll: number = 0;
+
+  /**
+   * Gets the number of pixels scrolled by the mouse event taking into account what type of delta
+   * is being used.
+   * @param ev The mouse wheel event.
+   */
+  private _consumeWheelEvent(ev: WheelEvent): number {
+    // Do nothing if it's not a vertical scroll event
+    if (ev.deltaY === 0 || ev.shiftKey) {
+      return 0;
+    }
+
+    if (!this._coreBrowserService || !this._renderService) {
+      return 0;
+    }
+    // Fallback to WheelEvent.DOM_DELTA_LINE
+    const targetWheelEventPixels = this._renderService.dimensions.device.cell.height / this._coreBrowserService.dpr;
+    let amount = 1;
+    if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
+      amount /= targetWheelEventPixels + 0.0; // Prevent integer division
+      this._wheelPartialScroll += amount;
+      amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
+      this._wheelPartialScroll %= 1;
+    } else if (ev.deltaMode === WheelEvent.DOM_DELTA_PAGE) {
+      amount *= this._bufferService.rows;
+    }
+    return amount;
+  }
 
   /**
    * Tells the renderer to refresh terminal content between two rows (inclusive) at the next

From ebddd5d3465b63aaae8379484694ef4a012db4f7 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Thu, 28 Aug 2025 22:54:50 -0700
Subject: [PATCH 10/22] Move from CoreBrowerTerminal to CoreMouseService. Still
 slow though

---
 src/browser/CoreBrowserTerminal.ts      | 43 ++++++-------------------
 src/common/TestUtils.test.ts            |  3 ++
 src/common/services/CoreMouseService.ts | 30 +++++++++++++++++
 src/common/services/Services.ts         |  5 +++
 4 files changed, 48 insertions(+), 33 deletions(-)

diff --git a/src/browser/CoreBrowserTerminal.ts b/src/browser/CoreBrowserTerminal.ts
index 37b33f7e..6ba27b66 100644
--- a/src/browser/CoreBrowserTerminal.ts
+++ b/src/browser/CoreBrowserTerminal.ts
@@ -646,7 +646,11 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           if (deltaY === 0) {
             return false;
           }
-          const lines = self._consumeWheelEvent(ev as WheelEvent);
+          const lines = self.coreMouseService.consumeWhellEvent(
+            ev as WheelEvent,
+            self._renderService?.dimensions?.device?.cell?.height,
+            self._coreBrowserService?.dpr
+          );
           if (lines === 0) {
             return false;
           }
@@ -821,7 +825,11 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           return false;
         }
 
-        const lines = self._consumeWheelEvent(ev as WheelEvent);
+        const lines = self.coreMouseService.consumeWhellEvent(
+          ev as WheelEvent,
+          self._renderService?.dimensions?.device?.cell?.height,
+          self._coreBrowserService?.dpr
+        );
         if (lines === 0) {
           return false;
         }
@@ -834,38 +842,7 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
     }, { passive: false }));
   }
 
-  // Stores a partial line amount when scrolling, this is used to keep track of how much of a line
-  // is scrolled so we can "scroll" over partial lines and feel natural on touchpads. This is a
-  // quick fix and could have a more robust solution in place that reset the value when needed.
-  private _wheelPartialScroll: number = 0;
 
-  /**
-   * Gets the number of pixels scrolled by the mouse event taking into account what type of delta
-   * is being used.
-   * @param ev The mouse wheel event.
-   */
-  private _consumeWheelEvent(ev: WheelEvent): number {
-    // Do nothing if it's not a vertical scroll event
-    if (ev.deltaY === 0 || ev.shiftKey) {
-      return 0;
-    }
-
-    if (!this._coreBrowserService || !this._renderService) {
-      return 0;
-    }
-    // Fallback to WheelEvent.DOM_DELTA_LINE
-    const targetWheelEventPixels = this._renderService.dimensions.device.cell.height / this._coreBrowserService.dpr;
-    let amount = 1;
-    if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
-      amount /= targetWheelEventPixels + 0.0; // Prevent integer division
-      this._wheelPartialScroll += amount;
-      amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
-      this._wheelPartialScroll %= 1;
-    } else if (ev.deltaMode === WheelEvent.DOM_DELTA_PAGE) {
-      amount *= this._bufferService.rows;
-    }
-    return amount;
-  }
 
   /**
    * Tells the renderer to refresh terminal content between two rows (inclusive) at the next
diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index 127e1f24..b25a2182 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -66,6 +66,9 @@ export class MockCoreMouseService implements ICoreMouseService {
   public explainEvents(events: CoreMouseEventType): { [event: string]: boolean } {
     throw new Error('Method not implemented.');
   }
+  public consumeWhellEvent(ev: WheelEvent, cellHeight: number, dpr: number): number {
+    return 1; // Return a simple mock value
+  }
 }
 
 export class MockCharsetService implements ICharsetService {
diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index f2f02379..a1135a8a 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -174,6 +174,7 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
   private _activeProtocol: string = '';
   private _activeEncoding: string = '';
   private _lastEvent: ICoreMouseEvent | null = null;
+  private _wheelPartialScroll: number = 0;
 
   private readonly _onProtocolChange = this._register(new Emitter<CoreMouseEventType>());
   public readonly onProtocolChange =  this._onProtocolChange.event;
@@ -229,6 +230,35 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
     this.activeProtocol = 'NONE';
     this.activeEncoding = 'DEFAULT';
     this._lastEvent = null;
+    this._wheelPartialScroll = 0;
+  }
+
+  /**
+   * Processes a wheel event, accounting for partial scrolls for trackpad, mouse scrolls.
+   * This prevents hyper-sensitive scrolling in alt buffer.
+   */
+  public consumeWhellEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number {
+    // Do nothing if it's not a vertical scroll event
+    if (ev.deltaY === 0 || ev.shiftKey) {
+      return 0;
+    }
+
+    if (cellHeight === undefined || dpr === undefined) {
+      return 0;
+    }
+
+    // Fallback to WheelEvent.DOM_DELTA_LINE
+    const targetWheelEventPixels = cellHeight / dpr;
+    let amount = 1;
+    if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
+      amount /= targetWheelEventPixels + 0.0; // Prevent integer division
+      this._wheelPartialScroll += amount;
+      amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
+      this._wheelPartialScroll %= 1;
+    } else if (ev.deltaMode === WheelEvent.DOM_DELTA_PAGE) {
+      amount *= this._bufferService.rows;
+    }
+    return amount;
   }
 
   /**
diff --git a/src/common/services/Services.ts b/src/common/services/Services.ts
index 9c3aebf7..e7ccc241 100644
--- a/src/common/services/Services.ts
+++ b/src/common/services/Services.ts
@@ -58,6 +58,11 @@ export interface ICoreMouseService {
    * Human readable version of mouse events.
    */
   explainEvents(events: CoreMouseEventType): { [event: string]: boolean };
+
+  /**
+   * Process wheel event taking partial scroll into account.
+   */
+  consumeWhellEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number;
 }
 
 export const ICoreService = createDecorator<ICoreService>('CoreService');

From b104a5b953a22329917b5d22378465279e5b9eaf Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Thu, 28 Aug 2025 22:56:15 -0700
Subject: [PATCH 11/22] Respect original formatting

---
 src/browser/CoreBrowserTerminal.ts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/browser/CoreBrowserTerminal.ts b/src/browser/CoreBrowserTerminal.ts
index 6ba27b66..bd513573 100644
--- a/src/browser/CoreBrowserTerminal.ts
+++ b/src/browser/CoreBrowserTerminal.ts
@@ -843,7 +843,6 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
   }
 
 
-
   /**
    * Tells the renderer to refresh terminal content between two rows (inclusive) at the next
    * opportunity.

From 26ecba8de1f5205c8a8f577c4ebce687ac23be84 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Mon, 8 Sep 2025 21:03:05 -0700
Subject: [PATCH 12/22] Fix sluggish mouse problem. Now similar to trackpad

---
 src/browser/CoreBrowserTerminal.ts      | 4 ++--
 src/common/TestUtils.test.ts            | 2 +-
 src/common/services/CoreMouseService.ts | 5 +++--
 src/common/services/Services.ts         | 2 +-
 4 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/browser/CoreBrowserTerminal.ts b/src/browser/CoreBrowserTerminal.ts
index bd513573..c9349760 100644
--- a/src/browser/CoreBrowserTerminal.ts
+++ b/src/browser/CoreBrowserTerminal.ts
@@ -646,7 +646,7 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           if (deltaY === 0) {
             return false;
           }
-          const lines = self.coreMouseService.consumeWhellEvent(
+          const lines = self.coreMouseService.consumeWheelEvent(
             ev as WheelEvent,
             self._renderService?.dimensions?.device?.cell?.height,
             self._coreBrowserService?.dpr
@@ -825,7 +825,7 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           return false;
         }
 
-        const lines = self.coreMouseService.consumeWhellEvent(
+        const lines = self.coreMouseService.consumeWheelEvent(
           ev as WheelEvent,
           self._renderService?.dimensions?.device?.cell?.height,
           self._coreBrowserService?.dpr
diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index b25a2182..1ee79e75 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -66,7 +66,7 @@ export class MockCoreMouseService implements ICoreMouseService {
   public explainEvents(events: CoreMouseEventType): { [event: string]: boolean } {
     throw new Error('Method not implemented.');
   }
-  public consumeWhellEvent(ev: WheelEvent, cellHeight: number, dpr: number): number {
+  public consumeWheelEvent(ev: WheelEvent, cellHeight: number, dpr: number): number {
     return 1; // Return a simple mock value
   }
 }
diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index a1135a8a..7f3d5f39 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -237,7 +237,7 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
    * Processes a wheel event, accounting for partial scrolls for trackpad, mouse scrolls.
    * This prevents hyper-sensitive scrolling in alt buffer.
    */
-  public consumeWhellEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number {
+  public consumeWheelEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number {
     // Do nothing if it's not a vertical scroll event
     if (ev.deltaY === 0 || ev.shiftKey) {
       return 0;
@@ -251,7 +251,8 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
     const targetWheelEventPixels = cellHeight / dpr;
     let amount = 1;
     if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
-      amount /= targetWheelEventPixels + 0.0; // Prevent integer division
+      const pixelAmount = ev.deltaY;
+      amount = pixelAmount / (targetWheelEventPixels + 0.0); // Prevent integer division
       this._wheelPartialScroll += amount;
       amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
       this._wheelPartialScroll %= 1;
diff --git a/src/common/services/Services.ts b/src/common/services/Services.ts
index e7ccc241..d47c3bbc 100644
--- a/src/common/services/Services.ts
+++ b/src/common/services/Services.ts
@@ -62,7 +62,7 @@ export interface ICoreMouseService {
   /**
    * Process wheel event taking partial scroll into account.
    */
-  consumeWhellEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number;
+  consumeWheelEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number;
 }
 
 export const ICoreService = createDecorator<ICoreService>('CoreService');

From 50df7a69e61a6e49ec8c082231339bbb40bbc026 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Mon, 8 Sep 2025 21:06:37 -0700
Subject: [PATCH 13/22] remove unused var

---
 src/common/services/CoreMouseService.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index 7f3d5f39..bf01d73c 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -251,8 +251,7 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
     const targetWheelEventPixels = cellHeight / dpr;
     let amount = 1;
     if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
-      const pixelAmount = ev.deltaY;
-      amount = pixelAmount / (targetWheelEventPixels + 0.0); // Prevent integer division
+      amount = ev.deltaY / (targetWheelEventPixels + 0.0); // Prevent integer division
       this._wheelPartialScroll += amount;
       amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
       this._wheelPartialScroll %= 1;

From d862c823861ce04ef304bec2b1f028f69e3c98da Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Mon, 8 Sep 2025 21:14:20 -0700
Subject: [PATCH 14/22] no stale comments

---
 src/common/TestUtils.test.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index 1ee79e75..499fb787 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -67,7 +67,7 @@ export class MockCoreMouseService implements ICoreMouseService {
     throw new Error('Method not implemented.');
   }
   public consumeWheelEvent(ev: WheelEvent, cellHeight: number, dpr: number): number {
-    return 1; // Return a simple mock value
+    return 1;
   }
 }
 

From cf6b868dfbf1f10885e53b3c841f188ff3204037 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 11:51:27 -0700
Subject: [PATCH 15/22] fastScrollModifier seems deprecated

---
 src/common/services/CoreMouseService.ts | 31 +++++++++++++++++++++----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index bf01d73c..e777f007 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -2,7 +2,7 @@
  * Copyright (c) 2019 The xterm.js authors. All rights reserved.
  * @license MIT
  */
-import { IBufferService, ICoreService, ICoreMouseService } from 'common/services/Services';
+import { IBufferService, ICoreService, ICoreMouseService, IOptionsService } from 'common/services/Services';
 import { ICoreMouseProtocol, ICoreMouseEvent, CoreMouseEncoding, CoreMouseEventType, CoreMouseButton, CoreMouseAction } from 'common/Types';
 import { Disposable } from 'vs/base/common/lifecycle';
 import { Emitter } from 'vs/base/common/event';
@@ -181,7 +181,8 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
 
   constructor(
     @IBufferService private readonly _bufferService: IBufferService,
-    @ICoreService private readonly _coreService: ICoreService
+    @ICoreService private readonly _coreService: ICoreService,
+    @IOptionsService private readonly _optionsService: IOptionsService
   ) {
     super();
     // register default protocols and encodings
@@ -247,11 +248,17 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
       return 0;
     }
 
-    // Fallback to WheelEvent.DOM_DELTA_LINE
     const targetWheelEventPixels = cellHeight / dpr;
-    let amount = 1;
+    let amount = this._applyScrollModifier(ev.deltaY, ev);
+
     if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
-      amount = ev.deltaY / (targetWheelEventPixels + 0.0); // Prevent integer division
+      amount /= (targetWheelEventPixels + 0.0); // Prevent integer division
+
+      const isLikelyTrackpad = Math.abs(ev.deltaY) < 50;
+      if (isLikelyTrackpad) {
+        amount *= 0.3;
+      }
+
       this._wheelPartialScroll += amount;
       amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
       this._wheelPartialScroll %= 1;
@@ -261,6 +268,20 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
     return amount;
   }
 
+  private _applyScrollModifier(amount: number, ev: WheelEvent): number {
+    const modifier = this._optionsService.rawOptions.fastScrollModifier; // QUESTION: This is always alt. Seems deprecated via: https://github.com/xtermjs/xterm.js/blob/5.5.0/src/browser/Viewport.ts
+    console.log('what is this modifier: ', modifier);
+
+    // Multiply the scroll speed when the modifier key is pressed
+    if ((modifier === 'alt' && ev.altKey) ||
+        (modifier === 'ctrl' && ev.ctrlKey) ||
+        (modifier === 'shift' && ev.shiftKey)) {
+      return amount * this._optionsService.rawOptions.fastScrollSensitivity * this._optionsService.rawOptions.scrollSensitivity;
+    }
+
+    return amount * this._optionsService.rawOptions.scrollSensitivity;
+  }
+
   /**
    * Triggers a mouse event to be sent.
    *

From 03ce26c6975ad2f71276a87e984bf9bec0503db5 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 11:56:28 -0700
Subject: [PATCH 16/22] Questions, possible concern

---
 src/common/services/CoreMouseService.ts | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index e777f007..da94ed97 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -177,7 +177,7 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
   private _wheelPartialScroll: number = 0;
 
   private readonly _onProtocolChange = this._register(new Emitter<CoreMouseEventType>());
-  public readonly onProtocolChange =  this._onProtocolChange.event;
+  public readonly onProtocolChange = this._onProtocolChange.event;
 
   constructor(
     @IBufferService private readonly _bufferService: IBufferService,
@@ -270,12 +270,16 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
 
   private _applyScrollModifier(amount: number, ev: WheelEvent): number {
     const modifier = this._optionsService.rawOptions.fastScrollModifier; // QUESTION: This is always alt. Seems deprecated via: https://github.com/xtermjs/xterm.js/blob/5.5.0/src/browser/Viewport.ts
-    console.log('what is this modifier: ', modifier);
+    // Problem is that modifier always seem 'alt' even when ev.ctrlKey is true, for example.
+    // Maybe this doesnt matter because all of alt, ctrl, shift does same operation?
 
     // Multiply the scroll speed when the modifier key is pressed
     if ((modifier === 'alt' && ev.altKey) ||
-        (modifier === 'ctrl' && ev.ctrlKey) ||
-        (modifier === 'shift' && ev.shiftKey)) {
+      (modifier === 'ctrl' && ev.ctrlKey) ||
+      (modifier === 'shift' && ev.shiftKey)) {
+
+      console.log('fast scroll sensitivity: ', this._optionsService.rawOptions.fastScrollSensitivity);
+      console.log('regular scroll sensitivity: ', this._optionsService.rawOptions.scrollSensitivity);
       return amount * this._optionsService.rawOptions.fastScrollSensitivity * this._optionsService.rawOptions.scrollSensitivity;
     }
 

From 1a6a807f6816de4d14a5138817afa8dcc5df595d Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 11:59:29 -0700
Subject: [PATCH 17/22] Remove stale comment

---
 src/common/services/CoreMouseService.ts | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index da94ed97..99cd1fc5 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -278,8 +278,6 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
       (modifier === 'ctrl' && ev.ctrlKey) ||
       (modifier === 'shift' && ev.shiftKey)) {
 
-      console.log('fast scroll sensitivity: ', this._optionsService.rawOptions.fastScrollSensitivity);
-      console.log('regular scroll sensitivity: ', this._optionsService.rawOptions.scrollSensitivity);
       return amount * this._optionsService.rawOptions.fastScrollSensitivity * this._optionsService.rawOptions.scrollSensitivity;
     }
 

From 38bee71630a4680cb86b1df00adfd1b9a28973c7 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 12:00:19 -0700
Subject: [PATCH 18/22] More clear comments

---
 src/common/services/CoreMouseService.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index 99cd1fc5..9b74daeb 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -271,7 +271,7 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
   private _applyScrollModifier(amount: number, ev: WheelEvent): number {
     const modifier = this._optionsService.rawOptions.fastScrollModifier; // QUESTION: This is always alt. Seems deprecated via: https://github.com/xtermjs/xterm.js/blob/5.5.0/src/browser/Viewport.ts
     // Problem is that modifier always seem 'alt' even when ev.ctrlKey is true, for example.
-    // Maybe this doesnt matter because all of alt, ctrl, shift does same operation?
+    // May need to tweak conditional to: if any of `ev.altKey || ev.ctrlKey || ev.shiftKey` is true
 
     // Multiply the scroll speed when the modifier key is pressed
     if ((modifier === 'alt' && ev.altKey) ||

From e4f222f6b00ed853895b154f65c86d0a2a742312 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 12:03:51 -0700
Subject: [PATCH 19/22] Make test happy

---
 src/common/services/CoreMouseService.test.ts | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/common/services/CoreMouseService.test.ts b/src/common/services/CoreMouseService.test.ts
index 34710897..3b79596d 100644
--- a/src/common/services/CoreMouseService.test.ts
+++ b/src/common/services/CoreMouseService.test.ts
@@ -3,13 +3,14 @@
  * @license MIT
  */
 import { CoreMouseService } from 'common/services/CoreMouseService';
-import { MockCoreService, MockBufferService } from 'common/TestUtils.test';
+import { MockCoreService, MockBufferService, MockOptionsService } from 'common/TestUtils.test';
 import { assert } from 'chai';
 import { ICoreMouseEvent, CoreMouseEventType, CoreMouseButton, CoreMouseAction } from 'common/Types';
 
 // needed mock services
 const bufferService = new MockBufferService(300, 100);
 const coreService = new MockCoreService();
+const optionsService = new MockOptionsService();
 
 function toBytes(s: string | undefined): number[] {
   if (!s) {
@@ -24,20 +25,20 @@ function toBytes(s: string | undefined): number[] {
 
 describe('CoreMouseService', () => {
   it('init', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     assert.equal(cms.activeEncoding, 'DEFAULT');
     assert.equal(cms.activeProtocol, 'NONE');
   });
   it('default protocols - NONE, X10, VT200, DRAG, ANY', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     assert.deepEqual(Object.keys((cms as any)._protocols), ['NONE', 'X10', 'VT200', 'DRAG', 'ANY']);
   });
   it('default encodings - DEFAULT, SGR', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     assert.deepEqual(Object.keys((cms as any)._encodings), ['DEFAULT', 'SGR', 'SGR_PIXELS']);
   });
   it('protocol/encoding setter, reset', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     cms.activeEncoding = 'SGR';
     cms.activeProtocol = 'ANY';
     assert.equal(cms.activeEncoding, 'SGR');
@@ -49,19 +50,19 @@ describe('CoreMouseService', () => {
     assert.throws(() => { cms.activeProtocol = 'xyz'; }, 'unknown protocol "xyz"');
   });
   it('addEncoding', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     cms.addEncoding('XYZ', (e: ICoreMouseEvent) => '');
     cms.activeEncoding = 'XYZ';
     assert.equal(cms.activeEncoding, 'XYZ');
   });
   it('addProtocol', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     cms.addProtocol('XYZ', { events: CoreMouseEventType.NONE, restrict: (e: ICoreMouseEvent) => false });
     cms.activeProtocol = 'XYZ';
     assert.equal(cms.activeProtocol, 'XYZ');
   });
   it('onProtocolChange', () => {
-    const cms = new CoreMouseService(bufferService, coreService);
+    const cms = new CoreMouseService(bufferService, coreService, optionsService);
     const wantedEvents: CoreMouseEventType[] = [];
     cms.onProtocolChange(events => wantedEvents.push(events));
     cms.activeProtocol = 'NONE';
@@ -76,7 +77,7 @@ describe('CoreMouseService', () => {
     let cms: CoreMouseService;
     let reports: string[];
     beforeEach(() => {
-      cms = new CoreMouseService(bufferService, coreService);
+      cms = new CoreMouseService(bufferService, coreService, optionsService);
       reports = [];
       coreService.triggerDataEvent = (data: string, userInput?: boolean) => reports.push(data);
       coreService.triggerBinaryEvent = (data: string) => reports.push(data);

From 9c42fb348b38a9fa7a1cc817edcb63059652dfc0 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 9 Sep 2025 13:21:37 -0700
Subject: [PATCH 20/22] ignore fastScrollModifier

---
 src/common/services/CoreMouseService.ts | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index 9b74daeb..a10ddafb 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -269,18 +269,10 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
   }
 
   private _applyScrollModifier(amount: number, ev: WheelEvent): number {
-    const modifier = this._optionsService.rawOptions.fastScrollModifier; // QUESTION: This is always alt. Seems deprecated via: https://github.com/xtermjs/xterm.js/blob/5.5.0/src/browser/Viewport.ts
-    // Problem is that modifier always seem 'alt' even when ev.ctrlKey is true, for example.
-    // May need to tweak conditional to: if any of `ev.altKey || ev.ctrlKey || ev.shiftKey` is true
-
     // Multiply the scroll speed when the modifier key is pressed
-    if ((modifier === 'alt' && ev.altKey) ||
-      (modifier === 'ctrl' && ev.ctrlKey) ||
-      (modifier === 'shift' && ev.shiftKey)) {
-
+    if (ev.altKey || ev.ctrlKey || ev.shiftKey) {
       return amount * this._optionsService.rawOptions.fastScrollSensitivity * this._optionsService.rawOptions.scrollSensitivity;
     }
-
     return amount * this._optionsService.rawOptions.scrollSensitivity;
   }
 

From 6e833e5d5d958642117eca457be7e18d61b799a5 Mon Sep 17 00:00:00 2001
From: Daniel Imms <2193314+Tyriar@users.noreply.github.com>
Date: Wed, 17 Sep 2025 07:33:43 -0700
Subject: [PATCH 21/22] Add proper typing for search results change event

- Export ISearchResultChangeEvent interface in addon-search
- Use proper Event<T> typing instead of inline object
- Improve API consistency and type safety for consumers
---
 addons/addon-search/src/SearchAddon.ts        | 11 ++++++++---
 addons/addon-search/test/SearchAddon.test.ts  |  2 +-
 addons/addon-search/typings/addon-search.d.ts | 18 ++++++++++++++++--
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/addons/addon-search/src/SearchAddon.ts b/addons/addon-search/src/SearchAddon.ts
index 8395e437..b65cfdd6 100644
--- a/addons/addon-search/src/SearchAddon.ts
+++ b/addons/addon-search/src/SearchAddon.ts
@@ -5,7 +5,7 @@
 
 import type { Terminal, IDisposable, ITerminalAddon, IDecoration } from '@xterm/xterm';
 import type { SearchAddon as ISearchApi } from '@xterm/addon-search';
-import { Emitter } from 'vs/base/common/event';
+import { Emitter, Event } from 'vs/base/common/event';
 import { combinedDisposable, Disposable, dispose, MutableDisposable, toDisposable } from 'vs/base/common/lifecycle';
 
 export interface ISearchOptions {
@@ -31,6 +31,11 @@ export interface ISearchPosition {
   startRow: number;
 }
 
+export interface ISearchResultChangeEvent {
+  resultIndex: number;
+  resultCount: number;
+}
+
 export interface ISearchAddonOptions {
   highlightLimit: number;
 }
@@ -86,8 +91,8 @@ export class SearchAddon extends Disposable implements ITerminalAddon , ISearchA
   private _linesCacheTimeoutId = 0;
   private _linesCacheDisposables = new MutableDisposable();
 
-  private readonly _onDidChangeResults = this._register(new Emitter<{ resultIndex: number, resultCount: number }>());
-  public readonly onDidChangeResults = this._onDidChangeResults.event;
+  private readonly _onDidChangeResults = this._register(new Emitter<ISearchResultChangeEvent>());
+  public get onDidChangeResults(): Event<ISearchResultChangeEvent> { return this._onDidChangeResults.event; }
 
   constructor(options?: Partial<ISearchAddonOptions>) {
     super();
diff --git a/addons/addon-search/test/SearchAddon.test.ts b/addons/addon-search/test/SearchAddon.test.ts
index 232686b4..7b551e0c 100644
--- a/addons/addon-search/test/SearchAddon.test.ts
+++ b/addons/addon-search/test/SearchAddon.test.ts
@@ -19,8 +19,8 @@ test.afterAll(async () => await ctx.page.close());
 test.describe('Search Tests', () => {
 
   test.beforeEach(async () => {
+    await ctx.proxy.reset();
     await ctx.page.evaluate(`
-      window.term.reset()
       window.search?.dispose();
       window.search = new SearchAddon();
       window.term.loadAddon(window.search);
diff --git a/addons/addon-search/typings/addon-search.d.ts b/addons/addon-search/typings/addon-search.d.ts
index 282004a2..4c0df5a6 100644
--- a/addons/addon-search/typings/addon-search.d.ts
+++ b/addons/addon-search/typings/addon-search.d.ts
@@ -75,6 +75,21 @@ declare module '@xterm/addon-search' {
     activeMatchColorOverviewRuler: string;
   }
 
+  /**
+   * Event data fired when search results change.
+   */
+  export interface ISearchResultChangeEvent {
+    /**
+     * The index of the currently active result, -1 when the threshold of matches is exceeded.
+     */
+    resultIndex: number;
+
+    /**
+     * The total number of search results found.
+     */
+    resultCount: number;
+  }
+
   /**
    * Options for the search addon.
    */
@@ -139,8 +154,7 @@ declare module '@xterm/addon-search' {
     /**
      * When decorations are enabled, fires when
      * the search results change.
-     * @returns -1 for resultIndex when the threshold of matches is exceeded.
      */
-    readonly onDidChangeResults: IEvent<{ resultIndex: number, resultCount: number }>;
+    readonly onDidChangeResults: IEvent<ISearchResultChangeEvent>;
   }
 }

From 87a45acae77b0147e01ff477eade1a6a93c9eec0 Mon Sep 17 00:00:00 2001
From: Daniel Imms <2193314+Tyriar@users.noreply.github.com>
Date: Wed, 17 Sep 2025 08:03:37 -0700
Subject: [PATCH 22/22] Refactor search constants and improve documentation

- Convert standalone constants to Constants enum with detailed docs
- Fix spacing issue in SearchAddon class declaration
- Update all references to use Constants enum for consistency
---
 addons/addon-search/src/SearchAddon.ts | 37 ++++++++++++++++++++------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/addons/addon-search/src/SearchAddon.ts b/addons/addon-search/src/SearchAddon.ts
index 8395e437..5e7c276c 100644
--- a/addons/addon-search/src/SearchAddon.ts
+++ b/addons/addon-search/src/SearchAddon.ts
@@ -63,11 +63,32 @@ interface IMultiHighlight extends IDisposable {
   match: ISearchResult;
 }
 
-const NON_WORD_CHARACTERS = ' ~!@#$%^&*()+`-=[]{}|\\;:"\',./<>?';
-const LINES_CACHE_TIME_TO_LIVE = 15 * 1000; // 15 secs
-const DEFAULT_HIGHLIGHT_LIMIT = 1000;
+/**
+ * Configuration constants for the search addon functionality.
+ */
+const enum Constants {
+  /**
+   * Characters that are considered non-word characters for search boundary detection. These
+   * characters are used to determine word boundaries when performing whole-word searches. Includes
+   * common punctuation, symbols, and whitespace characters.
+   */
+  NON_WORD_CHARACTERS = ' ~!@#$%^&*()+`-=[]{}|\\;:"\',./<>?',
 
-export class SearchAddon extends Disposable implements ITerminalAddon , ISearchApi {
+  /**
+   * Time-to-live for cached search results in milliseconds. After this duration, cached search
+   * results will be invalidated to ensure they remain consistent with terminal content changes.
+   */
+  LINES_CACHE_TIME_TO_LIVE = 15000,
+
+  /**
+   * Default maximum number of search results to highlight simultaneously. This limit prevents
+   * performance degradation when searching for very common terms that would result in excessive
+   * highlighting decorations.
+   */
+  DEFAULT_HIGHLIGHT_LIMIT = 1000
+}
+
+export class SearchAddon extends Disposable implements ITerminalAddon, ISearchApi {
   private _terminal: Terminal | undefined;
   private _cachedSearchTerm: string | undefined;
   private _highlightedLines: Set<number> = new Set();
@@ -92,7 +113,7 @@ export class SearchAddon extends Disposable implements ITerminalAddon , ISearchA
   constructor(options?: Partial<ISearchAddonOptions>) {
     super();
 
-    this._highlightLimit = options?.highlightLimit ?? DEFAULT_HIGHLIGHT_LIMIT;
+    this._highlightLimit = options?.highlightLimit ?? Constants.DEFAULT_HIGHLIGHT_LIMIT;
   }
 
   public activate(terminal: Terminal): void {
@@ -446,7 +467,7 @@ export class SearchAddon extends Disposable implements ITerminalAddon , ISearchA
     }
 
     window.clearTimeout(this._linesCacheTimeoutId);
-    this._linesCacheTimeoutId = window.setTimeout(() => this._destroyLinesCache(), LINES_CACHE_TIME_TO_LIVE);
+    this._linesCacheTimeoutId = window.setTimeout(() => this._destroyLinesCache(), Constants.LINES_CACHE_TIME_TO_LIVE);
   }
 
   private _destroyLinesCache(): void {
@@ -466,8 +487,8 @@ export class SearchAddon extends Disposable implements ITerminalAddon , ISearchA
    * @param term the substring that starts at searchIndex
    */
   private _isWholeWord(searchIndex: number, line: string, term: string): boolean {
-    return ((searchIndex === 0) || (NON_WORD_CHARACTERS.includes(line[searchIndex - 1]))) &&
-      (((searchIndex + term.length) === line.length) || (NON_WORD_CHARACTERS.includes(line[searchIndex + term.length])));
+    return ((searchIndex === 0) || (Constants.NON_WORD_CHARACTERS.includes(line[searchIndex - 1]))) &&
+      (((searchIndex + term.length) === line.length) || (Constants.NON_WORD_CHARACTERS.includes(line[searchIndex + term.length])));
   }
 
   /**