From 7392f65cf6eae59af7dd7fc9f5318aedc1d109d9 Mon Sep 17 00:00:00 2001
From: eli-w-king <elijahwilliamking@icloud.com>
Date: Fri, 13 Feb 2026 10:35:38 -0800
Subject: [PATCH 1/2] Revert "non-responsive panel content motion (#295011)"

This reverts commit 1443559d93517d8339ce3eab65dcd1d877984fc0.
---
 src/vs/base/browser/ui/splitview/splitview.ts | 37 ++++---------------
 1 file changed, 8 insertions(+), 29 deletions(-)

diff --git a/src/vs/base/browser/ui/splitview/splitview.ts b/src/vs/base/browser/ui/splitview/splitview.ts
index 2c72bd8d869..c6ac50b2ded 100644
--- a/src/vs/base/browser/ui/splitview/splitview.ts
+++ b/src/vs/base/browser/ui/splitview/splitview.ts
@@ -908,18 +908,13 @@ export class SplitView<TLayoutContext = undefined, TView extends IView<TLayoutCo
 			container.classList.add('visible');
 		}
 
-		// 6. Clip overflow on the animating container so that the view
-		//    content (rendered at its full target size) is revealed/hidden
-		//    smoothly as the container width animates.
-		container.style.overflow = 'hidden';
-
-		// The target size is the full (non-zero) panel size. During
-		// animation we re-layout the animating view at this fixed size
-		// after each frame so its content never reflows at intermediate
-		// widths/heights (prevents chat, extension icons, etc. from
-		// jumping around). Sibling views still receive interpolated sizes
-		// so the editor / bottom panel remain responsive.
-		const viewTargetSize = visible ? finalSizes[index] : startSizes[index];
+		// 6. Clip overflow on the target container while it shrinks.
+		//    Only apply for HIDE animations - for SHOW, we leave overflow alone
+		//    so that box-shadow / visual effects on the child Part are not clipped
+		//    by the parent container during the animation.
+		if (!visible) {
+			container.style.overflow = 'hidden';
+		}
 
 		// 6b. Set initial opacity for fade effect
 		container.style.opacity = visible ? '0' : '1';
@@ -930,12 +925,6 @@ export class SplitView<TLayoutContext = undefined, TView extends IView<TLayoutCo
 
 		// 8. Render the start state
 		this.layoutViews();
-		try {
-			this.viewItems[index].view.layout(viewTargetSize, 0, this.layoutContext);
-		} catch (e) {
-			console.error('Splitview: Failed to layout view during animation');
-			console.error(e);
-		}
 
 		// 9. Easing curve is pre-parsed - ready for JS evaluation
 
@@ -945,9 +934,9 @@ export class SplitView<TLayoutContext = undefined, TView extends IView<TLayoutCo
 				this.viewItems[i].size = finalSizes[i];
 			}
 			container.style.opacity = '';
-			container.style.overflow = '';
 			if (!visible) {
 				container.classList.remove('visible');
+				container.style.overflow = '';
 			}
 			this.layoutViews();
 			this.saveProportions();
@@ -1007,16 +996,6 @@ export class SplitView<TLayoutContext = undefined, TView extends IView<TLayoutCo
 
 			this.layoutViews();
 
-			// Re-layout the animating view at its full target size so its
-			// content does not reflow at intermediate sizes. The container
-			// is already at the interpolated size with overflow:hidden.
-			try {
-				this.viewItems[index].view.layout(viewTargetSize, 0, this.layoutContext);
-			} catch (e) {
-				console.error('Splitview: Failed to layout view during animation');
-				console.error(e);
-			}
-
 			if (t < 1) {
 				rafId = window.requestAnimationFrame(animate);
 			} else {

From a3fd9a09a07c9db6cecd8751f47fcd13ce1aab3a Mon Sep 17 00:00:00 2001
From: eli-w-king <elijahwilliamking@icloud.com>
Date: Fri, 13 Feb 2026 10:36:28 -0800
Subject: [PATCH 2/2] Revert "Merge pull request #294021 from
 microsoft/eli/workbench-motion"

This reverts commit 7e632ad633112793b46a9a0a2d01cd409fb63831, reversing
changes made to 386be2607ecbcdc59c5881f78f58335116faceb0.
---
 src/vs/base/browser/ui/grid/grid.ts           |   9 +-
 src/vs/base/browser/ui/grid/gridview.ts       |  10 +-
 src/vs/base/browser/ui/motion/motion.css      |   9 -
 src/vs/base/browser/ui/motion/motion.ts       | 155 --------------
 src/vs/base/browser/ui/splitview/splitview.ts | 192 +-----------------
 .../quickinput/browser/media/quickInput.css   |  32 ---
 .../browser/quickInputController.ts           |  35 +---
 src/vs/workbench/browser/layout.ts            | 112 ++++------
 src/vs/workbench/browser/media/motion.css     |  22 --
 src/vs/workbench/browser/style.ts             |   1 -
 10 files changed, 47 insertions(+), 530 deletions(-)
 delete mode 100644 src/vs/base/browser/ui/motion/motion.css
 delete mode 100644 src/vs/base/browser/ui/motion/motion.ts
 delete mode 100644 src/vs/workbench/browser/media/motion.css

diff --git a/src/vs/base/browser/ui/grid/grid.ts b/src/vs/base/browser/ui/grid/grid.ts
index f667738b748..ef9b1ba2462 100644
--- a/src/vs/base/browser/ui/grid/grid.ts
+++ b/src/vs/base/browser/ui/grid/grid.ts
@@ -9,10 +9,9 @@ import { Event } from '../../../common/event.js';
 import { Disposable } from '../../../common/lifecycle.js';
 import './gridview.css';
 import { Box, GridView, IGridViewOptions, IGridViewStyles, IView as IGridViewView, IViewSize, orthogonal, Sizing as GridViewSizing, GridLocation } from './gridview.js';
-import type { SplitView, AutoSizing as SplitViewAutoSizing, IViewVisibilityAnimationOptions } from '../splitview/splitview.js';
+import type { SplitView, AutoSizing as SplitViewAutoSizing } from '../splitview/splitview.js';
 
 export type { IViewSize };
-export type { IViewVisibilityAnimationOptions } from '../splitview/splitview.js';
 export { LayoutPriority, Orientation, orthogonal } from './gridview.js';
 
 export const enum Direction {
@@ -651,12 +650,10 @@ export class Grid<T extends IView = IView> extends Disposable {
 	 * Set the visibility state of a {@link IView view}.
 	 *
 	 * @param view The {@link IView view}.
-	 * @param visible Whether the view should be visible.
-	 * @param animation Optional animation options.
 	 */
-	setViewVisible(view: T, visible: boolean, animation?: IViewVisibilityAnimationOptions): void {
+	setViewVisible(view: T, visible: boolean): void {
 		const location = this.getViewLocation(view);
-		this.gridview.setViewVisible(location, visible, animation);
+		this.gridview.setViewVisible(location, visible);
 	}
 
 	/**
diff --git a/src/vs/base/browser/ui/grid/gridview.ts b/src/vs/base/browser/ui/grid/gridview.ts
index 03c416cfd89..112d7231f1a 100644
--- a/src/vs/base/browser/ui/grid/gridview.ts
+++ b/src/vs/base/browser/ui/grid/gridview.ts
@@ -5,7 +5,7 @@
 
 import { $ } from '../../dom.js';
 import { IBoundarySashes, Orientation, Sash } from '../sash/sash.js';
-import { DistributeSizing, ISplitViewStyles, IView as ISplitView, IViewVisibilityAnimationOptions, LayoutPriority, Sizing, AutoSizing, SplitView } from '../splitview/splitview.js';
+import { DistributeSizing, ISplitViewStyles, IView as ISplitView, LayoutPriority, Sizing, AutoSizing, SplitView } from '../splitview/splitview.js';
 import { equals as arrayEquals, tail } from '../../../common/arrays.js';
 import { Color } from '../../../common/color.js';
 import { Emitter, Event, Relay } from '../../../common/event.js';
@@ -615,7 +615,7 @@ class BranchNode implements ISplitView<ILayoutContext>, IDisposable {
 		return this.splitview.isViewVisible(index);
 	}
 
-	setChildVisible(index: number, visible: boolean, animation?: IViewVisibilityAnimationOptions): void {
+	setChildVisible(index: number, visible: boolean): void {
 		index = validateIndex(index, this.children.length);
 
 		if (this.splitview.isViewVisible(index) === visible) {
@@ -623,7 +623,7 @@ class BranchNode implements ISplitView<ILayoutContext>, IDisposable {
 		}
 
 		const wereAllChildrenHidden = this.splitview.contentSize === 0;
-		this.splitview.setViewVisible(index, visible, animation);
+		this.splitview.setViewVisible(index, visible);
 		const areAllChildrenHidden = this.splitview.contentSize === 0;
 
 		// If all children are hidden then the parent should hide the entire splitview
@@ -1663,7 +1663,7 @@ export class GridView implements IDisposable {
 	 *
 	 * @param location The {@link GridLocation location} of the view.
 	 */
-	setViewVisible(location: GridLocation, visible: boolean, animation?: IViewVisibilityAnimationOptions): void {
+	setViewVisible(location: GridLocation, visible: boolean): void {
 		if (this.hasMaximizedView()) {
 			this.exitMaximizedView();
 			return;
@@ -1676,7 +1676,7 @@ export class GridView implements IDisposable {
 			throw new Error('Invalid from location');
 		}
 
-		parent.setChildVisible(index, visible, animation);
+		parent.setChildVisible(index, visible);
 	}
 
 	/**
diff --git a/src/vs/base/browser/ui/motion/motion.css b/src/vs/base/browser/ui/motion/motion.css
deleted file mode 100644
index 69e257be2d3..00000000000
--- a/src/vs/base/browser/ui/motion/motion.css
+++ /dev/null
@@ -1,9 +0,0 @@
-/*---------------------------------------------------------------------------------------------
- *  Copyright (c) Microsoft Corporation. All rights reserved.
- *  Licensed under the MIT License. See License.txt in the project root for license information.
- *--------------------------------------------------------------------------------------------*/
-
-/* Utility class applied during panel animations to prevent content overflow */
-.monaco-split-view2 > .split-view-container > .split-view-view.motion-animating {
-	overflow: hidden;
-}
diff --git a/src/vs/base/browser/ui/motion/motion.ts b/src/vs/base/browser/ui/motion/motion.ts
deleted file mode 100644
index c2e8a045d41..00000000000
--- a/src/vs/base/browser/ui/motion/motion.ts
+++ /dev/null
@@ -1,155 +0,0 @@
-/*---------------------------------------------------------------------------------------------
- *  Copyright (c) Microsoft Corporation. All rights reserved.
- *  Licensed under the MIT License. See License.txt in the project root for license information.
- *--------------------------------------------------------------------------------------------*/
-
-import './motion.css';
-
-//#region Easing Curves
-
-/**
- * A pre-parsed cubic bezier easing curve that can be evaluated directly
- * without reparsing a CSS string on every frame.
- *
- * Given control points `(x1, y1)` and `(x2, y2)` (the CSS `cubic-bezier`
- * parameters), {@link solve} finds the bezier parameter `u` such that
- * `Bx(u) = t` using Newton's method, then returns `By(u)`.
- */
-export class CubicBezierCurve {
-
-	constructor(
-		readonly x1: number,
-		readonly y1: number,
-		readonly x2: number,
-		readonly y2: number,
-	) { }
-
-	/**
-	 * Evaluate the curve at time `t` (0-1), returning the eased value.
-	 */
-	solve(t: number): number {
-		if (t <= 0) {
-			return 0;
-		}
-		if (t >= 1) {
-			return 1;
-		}
-
-		// Newton's method to find u where Bx(u) = t
-		let u = t; // initial guess
-		for (let i = 0; i < 8; i++) {
-			const currentX = bezierComponent(u, this.x1, this.x2);
-			const error = currentX - t;
-			if (Math.abs(error) < 1e-6) {
-				break;
-			}
-			const dx = bezierComponentDerivative(u, this.x1, this.x2);
-			if (Math.abs(dx) < 1e-6) {
-				break;
-			}
-			u -= error / dx;
-		}
-
-		u = Math.max(0, Math.min(1, u));
-		return bezierComponent(u, this.y1, this.y2);
-	}
-
-	/**
-	 * Returns the CSS `cubic-bezier(…)` string representation, for use in
-	 * CSS `transition` or `animation` properties.
-	 */
-	toCssString(): string {
-		return `cubic-bezier(${this.x1}, ${this.y1}, ${this.x2}, ${this.y2})`;
-	}
-}
-
-/**
- * Fluent 2 ease-out curve - default for entrances and expansions.
- * Starts fast and decelerates to a stop.
- */
-export const EASE_OUT = new CubicBezierCurve(0.1, 0.9, 0.2, 1);
-
-/**
- * Fluent 2 ease-in curve - for exits and collapses.
- * Starts slow and accelerates out.
- */
-export const EASE_IN = new CubicBezierCurve(0.9, 0.1, 1, 0.2);
-
-//#endregion
-
-//#region Cubic Bezier Evaluation
-
-/**
- * Parses a CSS `cubic-bezier(x1, y1, x2, y2)` string into a
- * {@link CubicBezierCurve}. Returns a linear curve on parse failure.
- */
-export function parseCubicBezier(css: string): CubicBezierCurve {
-	const match = css.match(/cubic-bezier\(\s*([-\d.]+)\s*,\s*([-\d.]+)\s*,\s*([-\d.]+)\s*,\s*([-\d.]+)\s*\)/);
-	if (!match) {
-		return new CubicBezierCurve(0, 0, 1, 1);
-	}
-	return new CubicBezierCurve(parseFloat(match[1]), parseFloat(match[2]), parseFloat(match[3]), parseFloat(match[4]));
-}
-
-/** Evaluates one component of a cubic bezier: B(u) with control points p1, p2, endpoints 0 and 1. */
-function bezierComponent(u: number, p1: number, p2: number): number {
-	// B(u) = 3(1-u)^2*u*p1 + 3(1-u)*u^2*p2 + u^3
-	const oneMinusU = 1 - u;
-	return 3 * oneMinusU * oneMinusU * u * p1 + 3 * oneMinusU * u * u * p2 + u * u * u;
-}
-
-/** First derivative of a bezier component: B'(u). */
-function bezierComponentDerivative(u: number, p1: number, p2: number): number {
-	// B'(u) = 3(1-u)^2*p1 + 6(1-u)*u*(p2-p1) + 3*u^2*(1-p2)
-	const oneMinusU = 1 - u;
-	return 3 * oneMinusU * oneMinusU * p1 + 6 * oneMinusU * u * (p2 - p1) + 3 * u * u * (1 - p2);
-}
-
-//#endregion
-
-//#region Duration Scaling
-
-/**
- * Reference pixel distance at which the base duration constants apply.
- * Duration scales linearly: a 600px animation takes twice as long as a 300px
- * one, keeping perceived velocity constant.
- */
-const REFERENCE_DISTANCE = 300;
-
-/** Minimum animation duration in milliseconds (avoids sub-frame flickers). */
-const MIN_DURATION = 50;
-
-/** Maximum animation duration in milliseconds (avoids sluggish feel). */
-const MAX_DURATION = 300;
-
-/**
- * Scales a base animation duration proportionally to the pixel distance
- * being animated, so that perceived velocity stays constant regardless of
- * panel width.
- *
- * @param baseDuration The duration (ms) that applies at {@link REFERENCE_DISTANCE} pixels.
- * @param pixelDistance The actual number of pixels the view will resize.
- * @returns The scaled duration, clamped to [{@link MIN_DURATION}, {@link MAX_DURATION}].
- */
-export function scaleDuration(baseDuration: number, pixelDistance: number): number {
-	if (pixelDistance <= 0) {
-		return baseDuration;
-	}
-	const scaled = baseDuration * (pixelDistance / REFERENCE_DISTANCE);
-	return Math.round(Math.max(MIN_DURATION, Math.min(MAX_DURATION, scaled)));
-}
-
-//#endregion
-
-//#region Utility Functions
-
-/**
- * Checks whether motion is reduced by looking for the `monaco-reduce-motion`
- * class on an ancestor element. This integrates with VS Code's existing
- * accessibility infrastructure in {@link AccessibilityService}.
- */
-export function isMotionReduced(element: HTMLElement): boolean {
-	return element.closest('.monaco-reduce-motion') !== null;
-}
-
-//#endregion
diff --git a/src/vs/base/browser/ui/splitview/splitview.ts b/src/vs/base/browser/ui/splitview/splitview.ts
index c6ac50b2ded..35f2724c1a8 100644
--- a/src/vs/base/browser/ui/splitview/splitview.ts
+++ b/src/vs/base/browser/ui/splitview/splitview.ts
@@ -8,41 +8,15 @@ import { DomEmitter } from '../../event.js';
 import { ISashEvent as IBaseSashEvent, Orientation, Sash, SashState } from '../sash/sash.js';
 import { SmoothScrollableElement } from '../scrollbar/scrollableElement.js';
 import { pushToEnd, pushToStart, range } from '../../../common/arrays.js';
-import { CancellationToken } from '../../../common/cancellation.js';
 import { Color } from '../../../common/color.js';
 import { Emitter, Event } from '../../../common/event.js';
 import { combinedDisposable, Disposable, dispose, IDisposable, toDisposable } from '../../../common/lifecycle.js';
 import { clamp } from '../../../common/numbers.js';
 import { Scrollable, ScrollbarVisibility, ScrollEvent } from '../../../common/scrollable.js';
 import * as types from '../../../common/types.js';
-import { CubicBezierCurve, isMotionReduced, scaleDuration } from '../motion/motion.js';
 import './splitview.css';
 export { Orientation } from '../sash/sash.js';
 
-/**
- * Options for animating a view visibility change in a {@link SplitView}.
- */
-export interface IViewVisibilityAnimationOptions {
-
-	/** Transition duration in milliseconds. */
-	readonly duration: number;
-
-	/** The easing curve applied to the animation. */
-	readonly easing: CubicBezierCurve;
-
-	/**
-	 * Optional callback invoked when the animation finishes naturally.
-	 * NOT called if the animation is cancelled via the {@link token}.
-	 */
-	readonly onComplete?: () => void;
-
-	/**
-	 * A cancellation token that allows the caller to stop the animation.
-	 * When cancellation is requested the animation snaps to its final state.
-	 */
-	readonly token: CancellationToken;
-}
-
 export interface ISplitViewStyles {
 	readonly separatorBorder: Color;
 }
@@ -828,38 +802,14 @@ export class SplitView<TLayoutContext = undefined, TView extends IView<TLayoutCo
 	/**
 	 * Set a {@link IView view}'s visibility.
 	 *
-	 * When {@link animation} is provided and motion is not reduced, the
-	 * visibility change is animated. Otherwise the change is applied
-	 * instantly. Any in-flight animation is always cancelled first.
-	 *
 	 * @param index The {@link IView view} index.
 	 * @param visible Whether the {@link IView view} should be visible.
-	 * @param animation Optional animation options. When omitted (or when
-	 *   the user prefers reduced motion) the change is instant.
 	 */
-	setViewVisible(index: number, visible: boolean, animation?: IViewVisibilityAnimationOptions): void {
+	setViewVisible(index: number, visible: boolean): void {
 		if (index < 0 || index >= this.viewItems.length) {
 			throw new Error('Index out of bounds');
 		}
 
-		// Cancel any in-flight animation before changing visibility.
-		// An animated visibility change interpolates ALL view sizes each
-		// frame, so a concurrent change on a different view would be
-		// overwritten on the next frame. Snapping first prevents that.
-		this._cleanupMotion?.();
-		this._cleanupMotion = undefined;
-
-		if (animation && !animation.token.isCancellationRequested && !isMotionReduced(this.el) && this.viewItems[index].visible !== visible) {
-			this._setViewVisibleAnimated(index, visible, animation);
-		} else {
-			this._setViewVisibleInstant(index, visible);
-		}
-	}
-
-	/**
-	 * Apply the visibility change to the model without animation.
-	 */
-	private _setViewVisibleInstant(index: number, visible: boolean): void {
 		const viewItem = this.viewItems[index];
 		viewItem.setVisible(visible);
 
@@ -868,146 +818,6 @@ export class SplitView<TLayoutContext = undefined, TView extends IView<TLayoutCo
 		this.saveProportions();
 	}
 
-	/**
-	 * Animate the visibility change using `requestAnimationFrame`.
-	 *
-	 * Interpolates all view sizes on each frame, which naturally cascades
-	 * layout changes through nested splitviews in the grid hierarchy
-	 * (e.g., the bottom panel resizing when the sidebar animates).
-	 *
-	 * The animation can be cancelled via {@link IViewVisibilityAnimationOptions.token}.
-	 * {@link IViewVisibilityAnimationOptions.onComplete} is only called when the
-	 * animation finishes naturally (not on cancellation).
-	 */
-	private _setViewVisibleAnimated(index: number, visible: boolean, animation: IViewVisibilityAnimationOptions): void {
-		const { duration: baseDuration, easing, onComplete, token } = animation;
-
-		const container = this.viewContainer.children[index] as HTMLElement;
-		const window = getWindow(this.el);
-		let disposed = false;
-		let rafId: number | undefined;
-
-		// 1. Snapshot sizes BEFORE the visibility change (the animation start state)
-		const startSizes = this.viewItems.map(v => v.size);
-
-		// 2. Apply the target visibility to the model instantly.
-		//    This computes final sizes, fires events, updates sashes, etc.
-		this._setViewVisibleInstant(index, visible);
-
-		// 3. Snapshot sizes AFTER the visibility change (the animation end state)
-		const finalSizes = this.viewItems.map(v => v.size);
-
-		// 4. Restore start sizes so we can animate FROM them
-		for (let i = 0; i < this.viewItems.length; i++) {
-			this.viewItems[i].size = startSizes[i];
-		}
-
-		// 5. For hiding: the target container lost .visible class (→ display:none).
-		//    Restore it so content stays visible during the animation.
-		if (!visible) {
-			container.classList.add('visible');
-		}
-
-		// 6. Clip overflow on the target container while it shrinks.
-		//    Only apply for HIDE animations - for SHOW, we leave overflow alone
-		//    so that box-shadow / visual effects on the child Part are not clipped
-		//    by the parent container during the animation.
-		if (!visible) {
-			container.style.overflow = 'hidden';
-		}
-
-		// 6b. Set initial opacity for fade effect
-		container.style.opacity = visible ? '0' : '1';
-
-		// 7. Scale duration based on pixel distance for consistent perceived velocity
-		const pixelDistance = Math.abs(finalSizes[index] - startSizes[index]);
-		const duration = scaleDuration(baseDuration, pixelDistance);
-
-		// 8. Render the start state
-		this.layoutViews();
-
-		// 9. Easing curve is pre-parsed - ready for JS evaluation
-
-		// Helper: snap all sizes to final state and clean up
-		const applyFinalState = () => {
-			for (let i = 0; i < this.viewItems.length; i++) {
-				this.viewItems[i].size = finalSizes[i];
-			}
-			container.style.opacity = '';
-			if (!visible) {
-				container.classList.remove('visible');
-				container.style.overflow = '';
-			}
-			this.layoutViews();
-			this.saveProportions();
-		};
-
-		const cleanup = (completed: boolean) => {
-			if (disposed) {
-				return;
-			}
-			disposed = true;
-			tokenListener.dispose();
-			if (rafId !== undefined) {
-				window.cancelAnimationFrame(rafId);
-				rafId = undefined;
-			}
-			applyFinalState();
-			this._cleanupMotion = undefined;
-			if (completed) {
-				onComplete?.();
-			}
-		};
-		this._cleanupMotion = () => cleanup(false);
-
-		// Listen to the cancellation token so the caller can stop the animation
-		const tokenListener = token.onCancellationRequested(() => cleanup(false));
-
-		// 10. Animate via requestAnimationFrame
-		const startTime = performance.now();
-		const totalSize = this.size;
-
-		const animate = () => {
-			if (disposed) {
-				return;
-			}
-
-			const elapsed = performance.now() - startTime;
-			const t = Math.min(elapsed / duration, 1);
-			const easedT = easing.solve(t);
-
-			// Interpolate opacity for fade effect
-			container.style.opacity = String(visible ? easedT : 1 - easedT);
-
-			// Interpolate all view sizes
-			let runningTotal = 0;
-			for (let i = 0; i < this.viewItems.length; i++) {
-				if (i === this.viewItems.length - 1) {
-					// Last item absorbs rounding errors to maintain total = this.size
-					this.viewItems[i].size = totalSize - runningTotal;
-				} else {
-					const size = Math.round(
-						startSizes[i] + (finalSizes[i] - startSizes[i]) * easedT
-					);
-					this.viewItems[i].size = size;
-					runningTotal += size;
-				}
-			}
-
-			this.layoutViews();
-
-			if (t < 1) {
-				rafId = window.requestAnimationFrame(animate);
-			} else {
-				cleanup(true);
-			}
-		};
-
-		rafId = window.requestAnimationFrame(animate);
-	}
-
-	private _cleanupMotion: (() => void) | undefined;
-
 	/**
 	 * Returns the {@link IView view}'s size previously to being hidden.
 	 *
diff --git a/src/vs/platform/quickinput/browser/media/quickInput.css b/src/vs/platform/quickinput/browser/media/quickInput.css
index 9afd0964022..bd509719a3c 100644
--- a/src/vs/platform/quickinput/browser/media/quickInput.css
+++ b/src/vs/platform/quickinput/browser/media/quickInput.css
@@ -525,35 +525,3 @@
 	outline: 1px solid var(--vscode-list-focusOutline) !important;
 	outline-offset: -1px;
 }
-
-/* Entrance animation */
-@keyframes quick-input-entrance {
-	from {
-		opacity: 0;
-		transform: translateY(-8px);
-	}
-	to {
-		opacity: 1;
-		transform: translateY(0);
-	}
-}
-
-.quick-input-widget.animating-entrance {
-	animation: quick-input-entrance 150ms cubic-bezier(0.1, 0.9, 0.2, 1) forwards;
-}
-
-/* Exit animation */
-@keyframes quick-input-exit {
-	from {
-		opacity: 1;
-		transform: translateY(0);
-	}
-	to {
-		opacity: 0;
-		transform: translateY(-8px);
-	}
-}
-
-.quick-input-widget.animating-exit {
-	animation: quick-input-exit 50ms cubic-bezier(0.9, 0.1, 1, 0.2) forwards;
-}
diff --git a/src/vs/platform/quickinput/browser/quickInputController.ts b/src/vs/platform/quickinput/browser/quickInputController.ts
index 11964ea5a30..8e5283ef9ad 100644
--- a/src/vs/platform/quickinput/browser/quickInputController.ts
+++ b/src/vs/platform/quickinput/browser/quickInputController.ts
@@ -37,7 +37,6 @@ import { TriStateCheckbox, createToggleActionViewItemProvider } from '../../../b
 import { defaultCheckboxStyles } from '../../theme/browser/defaultStyles.js';
 import { QuickInputTreeController } from './tree/quickInputTreeController.js';
 import { QuickTree } from './tree/quickTree.js';
-import { isMotionReduced } from '../../../base/browser/ui/motion/motion.js';
 import { AnchorAlignment, AnchorPosition, layout2d } from '../../../base/common/layout.js';
 import { getAnchorRect } from '../../../base/browser/ui/contextview/contextview.js';
 
@@ -81,7 +80,6 @@ export class QuickInputController extends Disposable {
 
 	private viewState: QuickInputViewState | undefined;
 	private dndController: QuickInputDragAndDropController | undefined;
-	private _cancelExitAnimation: (() => void) | undefined;
 
 	private readonly inQuickInputContext: IContextKey<boolean>;
 	private readonly quickInputTypeContext: IContextKey<QuickInputType>;
@@ -713,26 +711,12 @@ export class QuickInputController extends Disposable {
 		const backKeybindingLabel = this.options.backKeybindingLabel();
 		backButton.tooltip = backKeybindingLabel ? localize('quickInput.backWithKeybinding', "Back ({0})", backKeybindingLabel) : localize('quickInput.back', "Back");
 
-		const wasVisible = ui.container.style.display !== 'none';
 		ui.container.style.display = '';
-		// Cancel any in-flight exit animation that would set display:none
-		this._cancelExitAnimation?.();
-		this._cancelExitAnimation = undefined;
 		this.updateLayout();
 		this.dndController?.setEnabled(!controller.anchor);
 		this.dndController?.layoutContainer();
 		ui.inputBox.setFocus();
 		this.quickInputTypeContext.set(controller.type);
-
-		// Animate entrance: fade in + slide down (only when first appearing)
-		if (!wasVisible && !isMotionReduced(ui.container)) {
-			ui.container.classList.add('animating-entrance');
-			const onAnimationEnd = () => {
-				ui.container.classList.remove('animating-entrance');
-				ui.container.removeEventListener('animationend', onAnimationEnd);
-			};
-			ui.container.addEventListener('animationend', onAnimationEnd);
-		}
 	}
 
 	isVisible(): boolean {
@@ -799,24 +783,7 @@ export class QuickInputController extends Disposable {
 		this.controller = null;
 		this.onHideEmitter.fire();
 		if (container) {
-			// Animate exit: fade out + slide up (faster than open)
-			if (!isMotionReduced(container)) {
-				container.classList.add('animating-exit');
-				const cleanupAnimation = () => {
-					container.classList.remove('animating-exit');
-					container.removeEventListener('animationend', onAnimationEnd);
-					this._cancelExitAnimation = undefined;
-				};
-				const onAnimationEnd = () => {
-					// Set display after animation completes to actually hide the element
-					container.style.display = 'none';
-					cleanupAnimation();
-				};
-				this._cancelExitAnimation = cleanupAnimation;
-				container.addEventListener('animationend', onAnimationEnd);
-			} else {
-				container.style.display = 'none';
-			}
+			container.style.display = 'none';
 		}
 		if (!focusChanged) {
 			let currentElement = this.previousFocusElement;
diff --git a/src/vs/workbench/browser/layout.ts b/src/vs/workbench/browser/layout.ts
index c7679ab51cb..b51e004b045 100644
--- a/src/vs/workbench/browser/layout.ts
+++ b/src/vs/workbench/browser/layout.ts
@@ -23,7 +23,7 @@ import { IHostService } from '../services/host/browser/host.js';
 import { IBrowserWorkbenchEnvironmentService } from '../services/environment/browser/environmentService.js';
 import { IEditorService } from '../services/editor/common/editorService.js';
 import { EditorGroupLayout, GroupActivationReason, GroupOrientation, GroupsOrder, IEditorGroupsService } from '../services/editor/common/editorGroupsService.js';
-import { SerializableGrid, ISerializableView, ISerializedGrid, Orientation, ISerializedNode, ISerializedLeafNode, Direction, IViewSize, Sizing, IViewVisibilityAnimationOptions } from '../../base/browser/ui/grid/grid.js';
+import { SerializableGrid, ISerializableView, ISerializedGrid, Orientation, ISerializedNode, ISerializedLeafNode, Direction, IViewSize, Sizing } from '../../base/browser/ui/grid/grid.js';
 import { Part } from './part.js';
 import { IStatusbarService } from '../services/statusbar/browser/statusbar.js';
 import { IFileService } from '../../platform/files/common/files.js';
@@ -47,8 +47,6 @@ import { AuxiliaryBarPart } from './parts/auxiliarybar/auxiliaryBarPart.js';
 import { ITelemetryService } from '../../platform/telemetry/common/telemetry.js';
 import { IAuxiliaryWindowService } from '../services/auxiliaryWindow/browser/auxiliaryWindowService.js';
 import { CodeWindow, mainWindow } from '../../base/browser/window.js';
-import { EASE_OUT, EASE_IN } from '../../base/browser/ui/motion/motion.js';
-import { CancellationToken } from '../../base/common/cancellation.js';
 
 //#region Layout Implementation
 
@@ -1870,32 +1868,27 @@ export abstract class Layout extends Disposable implements IWorkbenchLayoutServi
 
 		this.stateModel.setRuntimeValue(LayoutStateKeys.SIDEBAR_HIDDEN, hidden);
 
-		// Adjust CSS - for hiding, defer adding the class until animation
-		// completes so the part stays visible during the exit animation.
-		if (!hidden) {
+		// Adjust CSS
+		if (hidden) {
+			this.mainContainer.classList.add(LayoutClasses.SIDEBAR_HIDDEN);
+		} else {
 			this.mainContainer.classList.remove(LayoutClasses.SIDEBAR_HIDDEN);
 		}
 
 		// Propagate to grid
-		this.workbenchGrid.setViewVisible(
-			this.sideBarPartView,
-			!hidden,
-			createViewVisibilityAnimation(hidden, () => {
-				if (!hidden) { return; }
-				// Deferred to after close animation
-				this.mainContainer.classList.add(LayoutClasses.SIDEBAR_HIDDEN);
-				if (this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.Sidebar)) {
-					this.paneCompositeService.hideActivePaneComposite(ViewContainerLocation.Sidebar);
+		this.workbenchGrid.setViewVisible(this.sideBarPartView, !hidden);
 
-					if (!this.isAuxiliaryBarMaximized()) {
-						this.focusPanelOrEditor(); // do not auto focus when auxiliary bar is maximized
-					}
-				}
-			})
-		);
+		// If sidebar becomes hidden, also hide the current active Viewlet if any
+		if (hidden && this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.Sidebar)) {
+			this.paneCompositeService.hideActivePaneComposite(ViewContainerLocation.Sidebar);
+
+			if (!this.isAuxiliaryBarMaximized()) {
+				this.focusPanelOrEditor(); // do not auto focus when auxiliary bar is maximized
+			}
+		}
 
 		// If sidebar becomes visible, show last active Viewlet or default viewlet
-		if (!hidden && !this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.Sidebar)) {
+		else if (!hidden && !this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.Sidebar)) {
 			const viewletToOpen = this.paneCompositeService.getLastActivePaneCompositeId(ViewContainerLocation.Sidebar);
 			if (viewletToOpen) {
 				this.openViewContainer(ViewContainerLocation.Sidebar, viewletToOpen);
@@ -2019,6 +2012,13 @@ export abstract class Layout extends Disposable implements IWorkbenchLayoutServi
 
 		const panelOpensMaximized = this.panelOpensMaximized();
 
+		// Adjust CSS
+		if (hidden) {
+			this.mainContainer.classList.add(LayoutClasses.PANEL_HIDDEN);
+		} else {
+			this.mainContainer.classList.remove(LayoutClasses.PANEL_HIDDEN);
+		}
+
 		// If maximized and in process of hiding, unmaximize FIRST before
 		// changing visibility to prevent conflict with setEditorHidden
 		// which would force panel visible again (fixes #281772)
@@ -2026,30 +2026,13 @@ export abstract class Layout extends Disposable implements IWorkbenchLayoutServi
 			this.toggleMaximizedPanel();
 		}
 
-		// Adjust CSS - for hiding, defer adding the class until animation
-		// completes because `.nopanel .part.panel { display: none !important }`
-		// would instantly hide the panel content mid-animation.
-		if (!hidden) {
-			this.mainContainer.classList.remove(LayoutClasses.PANEL_HIDDEN);
-		}
-
 		// Propagate layout changes to grid
-		this.workbenchGrid.setViewVisible(
-			this.panelPartView,
-			!hidden,
-			createViewVisibilityAnimation(hidden, () => {
-				if (!hidden) { return; }
-				// Deferred to after close animation
-				this.mainContainer.classList.add(LayoutClasses.PANEL_HIDDEN);
-				if (this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.Panel)) {
-					this.paneCompositeService.hideActivePaneComposite(ViewContainerLocation.Panel);
-				}
-			})
-		);
+		this.workbenchGrid.setViewVisible(this.panelPartView, !hidden);
 
-		// If panel part becomes hidden, focus the editor after animation starts
+		// If panel part becomes hidden, also hide the current active panel if any
 		let focusEditor = false;
 		if (hidden && this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.Panel)) {
+			this.paneCompositeService.hideActivePaneComposite(ViewContainerLocation.Panel);
 			if (
 				!isIOS &&						// do not auto focus on iOS (https://github.com/microsoft/vscode/issues/127832)
 				!this.isAuxiliaryBarMaximized()	// do not auto focus when auxiliary bar is maximized
@@ -2223,30 +2206,24 @@ export abstract class Layout extends Disposable implements IWorkbenchLayoutServi
 
 		this.stateModel.setRuntimeValue(LayoutStateKeys.AUXILIARYBAR_HIDDEN, hidden);
 
-		// Adjust CSS - for hiding, defer adding the class until animation
-		// completes because `.noauxiliarybar .part.auxiliarybar { display: none !important }`
-		// would instantly hide the content mid-animation.
-		if (!hidden) {
+		// Adjust CSS
+		if (hidden) {
+			this.mainContainer.classList.add(LayoutClasses.AUXILIARYBAR_HIDDEN);
+		} else {
 			this.mainContainer.classList.remove(LayoutClasses.AUXILIARYBAR_HIDDEN);
 		}
 
 		// Propagate to grid
-		this.workbenchGrid.setViewVisible(
-			this.auxiliaryBarPartView,
-			!hidden,
-			createViewVisibilityAnimation(hidden, () => {
-				if (!hidden) { return; }
-				// Deferred to after close animation
-				this.mainContainer.classList.add(LayoutClasses.AUXILIARYBAR_HIDDEN);
-				if (this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.AuxiliaryBar)) {
-					this.paneCompositeService.hideActivePaneComposite(ViewContainerLocation.AuxiliaryBar);
-					this.focusPanelOrEditor();
-				}
-			})
-		);
+		this.workbenchGrid.setViewVisible(this.auxiliaryBarPartView, !hidden);
+
+		// If auxiliary bar becomes hidden, also hide the current active pane composite if any
+		if (hidden && this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.AuxiliaryBar)) {
+			this.paneCompositeService.hideActivePaneComposite(ViewContainerLocation.AuxiliaryBar);
+			this.focusPanelOrEditor();
+		}
 
 		// If auxiliary bar becomes visible, show last active pane composite or default pane composite
-		if (!hidden && !this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.AuxiliaryBar)) {
+		else if (!hidden && !this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.AuxiliaryBar)) {
 			let viewletToOpen: string | undefined = this.paneCompositeService.getLastActivePaneCompositeId(ViewContainerLocation.AuxiliaryBar);
 
 			// verify that the viewlet we try to open has views before we default to it
@@ -2739,21 +2716,6 @@ function getZenModeConfiguration(configurationService: IConfigurationService): Z
 	return configurationService.getValue<ZenModeConfiguration>(WorkbenchLayoutSettings.ZEN_MODE_CONFIG);
 }
 
-/** Duration (ms) for panel/sidebar open (entrance) animations. */
-const PANEL_OPEN_DURATION = 135;
-
-/** Duration (ms) for panel/sidebar close (exit) animations. */
-const PANEL_CLOSE_DURATION = 35;
-
-function createViewVisibilityAnimation(hidden: boolean, onComplete?: () => void, token: CancellationToken = CancellationToken.None): IViewVisibilityAnimationOptions {
-	return {
-		duration: hidden ? PANEL_CLOSE_DURATION : PANEL_OPEN_DURATION,
-		easing: hidden ? EASE_IN : EASE_OUT,
-		token,
-		onComplete,
-	};
-}
-
 //#endregion
 
 //#region Layout State Model
diff --git a/src/vs/workbench/browser/media/motion.css b/src/vs/workbench/browser/media/motion.css
deleted file mode 100644
index fbd8215265a..00000000000
--- a/src/vs/workbench/browser/media/motion.css
+++ /dev/null
@@ -1,22 +0,0 @@
-/*---------------------------------------------------------------------------------------------
- *  Copyright (c) Microsoft Corporation. All rights reserved.
- *  Licensed under the MIT License. See License.txt in the project root for license information.
- *--------------------------------------------------------------------------------------------*/
-
-/* Motion custom properties -- only active when motion is enabled */
-.monaco-workbench.monaco-enable-motion {
-	--vscode-motion-panel-open-duration: 175ms;
-	--vscode-motion-panel-close-duration: 75ms;
-	--vscode-motion-quick-input-open-duration: 175ms;
-	--vscode-motion-quick-input-close-duration: 75ms;
-	--vscode-motion-ease-out: cubic-bezier(0.1, 0.9, 0.2, 1);
-	--vscode-motion-ease-in: cubic-bezier(0.9, 0.1, 1, 0.2);
-}
-
-/* Disable all motion durations when reduced motion is active */
-.monaco-workbench.monaco-reduce-motion {
-	--vscode-motion-panel-open-duration: 0ms;
-	--vscode-motion-panel-close-duration: 0ms;
-	--vscode-motion-quick-input-open-duration: 0ms;
-	--vscode-motion-quick-input-close-duration: 0ms;
-}
diff --git a/src/vs/workbench/browser/style.ts b/src/vs/workbench/browser/style.ts
index de344e7e46b..9250ef3f280 100644
--- a/src/vs/workbench/browser/style.ts
+++ b/src/vs/workbench/browser/style.ts
@@ -4,7 +4,6 @@
  *--------------------------------------------------------------------------------------------*/
 
 import './media/style.css';
-import './media/motion.css';
 import { registerThemingParticipant } from '../../platform/theme/common/themeService.js';
 import { WORKBENCH_BACKGROUND, TITLE_BAR_ACTIVE_BACKGROUND } from '../common/theme.js';
 import { isWeb, isIOS } from '../../base/common/platform.js';