From 9415abf1cc9eb0cfe0a3d373afb708cca3d3ba80 Mon Sep 17 00:00:00 2001
From: "vs-code-engineering[bot]"
 <122617954+vs-code-engineering[bot]@users.noreply.github.com>
Date: Tue, 12 May 2026 16:07:08 +0000
Subject: [PATCH 01/27] fix: guard against null in doRemoveFromValueTree (fixes
 #316034)

typeof null === 'object' is true in JavaScript, so a null value in the
configuration tree passes the existing type guard and Object.keys(null)
throws 'Cannot convert undefined or null to object'.

Add explicit null check to the guard condition.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 src/vs/platform/configuration/common/configuration.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/vs/platform/configuration/common/configuration.ts b/src/vs/platform/configuration/common/configuration.ts
index e28c4a34a0a10..55eaae5451c23 100644
--- a/src/vs/platform/configuration/common/configuration.ts
+++ b/src/vs/platform/configuration/common/configuration.ts
@@ -302,7 +302,7 @@ function doRemoveFromValueTree(valueTree: IStringDictionary<unknown> | unknown,
 
 	if (Object.keys(valueTreeRecord).indexOf(first) !== -1) {
 		const value = valueTreeRecord[first];
-		if (typeof value === 'object' && !Array.isArray(value)) {
+		if (typeof value === 'object' && value !== null && !Array.isArray(value)) {
 			doRemoveFromValueTree(value, segments);
 			if (Object.keys(value as object).length === 0) {
 				delete valueTreeRecord[first];

From 9f70c92b79ffbc986fda32cf4146e354bd1dd168 Mon Sep 17 00:00:00 2001
From: Nikola Hristov <Nikola@PlayForm.Cloud>
Date: Tue, 12 May 2026 19:28:54 +0300
Subject: [PATCH 02/27] fix: restore protected modifier on
 relayCreationTimeoutMs in test helper

The `relayCreationTimeoutMs` override in `TestableSSHRemoteAgentHostMainService`
was missing its `protected` modifier, causing the mangler to promote it to
`public` and fail the `compile-build-with-mangling` step with:

  ERROR: Protected fields have been made PUBLIC. This hurts minification
  and is therefore not allowed.

Re-add `protected` to the override declaration to keep the field's
visibility consistent with the base class and satisfy the mangler.
---
 .../agentHost/test/node/sshRemoteAgentHostService.test.ts       | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/vs/platform/agentHost/test/node/sshRemoteAgentHostService.test.ts b/src/vs/platform/agentHost/test/node/sshRemoteAgentHostService.test.ts
index faa69ebd589bb..912704bafa89e 100644
--- a/src/vs/platform/agentHost/test/node/sshRemoteAgentHostService.test.ts
+++ b/src/vs/platform/agentHost/test/node/sshRemoteAgentHostService.test.ts
@@ -174,7 +174,7 @@ class TestableSSHRemoteAgentHostMainService extends SSHRemoteAgentHostMainServic
 	hangRelayCreationOnCall: number | undefined;
 
 	/** Public override so tests can shorten the relay creation timeout. */
-	override relayCreationTimeoutMs: number = 30_000;
+	protected override relayCreationTimeoutMs: number = 30_000;
 
 	/** Stored onMessage callbacks from relays, most recent last. */
 	private readonly _relayMessageCallbacks: Array<(data: string) => void> = [];

From c5061c3b6ac5ecbb6b579d2633846daa07376e66 Mon Sep 17 00:00:00 2001
From: Nikola Hristov <Nikola@PlayForm.Cloud>
Date: Tue, 12 May 2026 20:30:42 +0300
Subject: [PATCH 03/27] fix: expose relayCreationTimeoutMs via test-only setter
 to satisfy mangler

The field `relayCreationTimeoutMs` is `protected` in the base class. The
test subclass `TestableSSHRemoteAgentHostMainService` had overridden it
without an explicit access modifier, making it implicitly `public`. The
mangler correctly rejected this as it hurts minification.

Adding `protected` back satisfied the mangler but caused a TS2445 error
since the test was assigning to the field directly on an instance, which
is illegal for `protected` members outside the class hierarchy.

Fix by adding a narrow public setter `setRelayCreationTimeoutForTest` in
the test subclass. The field stays `protected`; the setter provides a
legitimate public entry point for tests.

Signed-off-by: Nikola Hristov <Nikola@PlayForm.Cloud>
---
 .../agentHost/test/node/sshRemoteAgentHostService.test.ts  | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/vs/platform/agentHost/test/node/sshRemoteAgentHostService.test.ts b/src/vs/platform/agentHost/test/node/sshRemoteAgentHostService.test.ts
index 912704bafa89e..6e6c87109e504 100644
--- a/src/vs/platform/agentHost/test/node/sshRemoteAgentHostService.test.ts
+++ b/src/vs/platform/agentHost/test/node/sshRemoteAgentHostService.test.ts
@@ -279,6 +279,11 @@ class TestableSSHRemoteAgentHostMainService extends SSHRemoteAgentHostMainServic
 			this._relayCloseCallbacks[this._relayCloseCallbacks.length - 1]();
 		}
 	}
+
+	/** Sets the relay creation timeout; exposed for tests only. */
+	setRelayCreationTimeoutForTest(ms: number): void {
+		this.relayCreationTimeoutMs = ms;
+	}
 }
 
 suite('SSHRemoteAgentHostMainService - connect flow', () => {
@@ -1017,7 +1022,7 @@ suite('SSHRemoteAgentHostMainService - connect flow', () => {
 		assert.strictEqual(originalClient.ended, false);
 
 		// Use a short timeout so the test completes quickly.
-		service.relayCreationTimeoutMs = 50;
+		service.setRelayCreationTimeoutForTest(50);
 		// Make the *reconnect* call's relay creation hang (the second relay).
 		service.hangRelayCreationOnCall = 2;
 

From 7326d2657545e36b31e5db3ebc9083f31a52b882 Mon Sep 17 00:00:00 2001
From: Matt Bierner <12821956+mjbvz@users.noreply.github.com>
Date: Tue, 12 May 2026 15:35:53 -0700
Subject: [PATCH 04/27] Enable output renderers for code blocks in chat

For #257761
---
 extensions/mermaid-chat-features/package.json |   3 +
 .../browser/mainThreadChatOutputRenderer.ts   |  16 +-
 .../workbench/api/common/extHost.protocol.ts  |   8 +-
 .../api/common/extHostChatOutputRenderer.ts   |   6 +-
 .../chat/browser/chatOutputItemRenderer.ts    |  87 +++++++--
 .../chatMarkdownContentPart.ts                | 182 +++++++++++++++++-
 .../chatMarkdownContentPart.test.ts           |  64 ++++++
 .../vscode.proposed.chatOutputRenderer.d.ts   |  26 ++-
 8 files changed, 365 insertions(+), 27 deletions(-)

diff --git a/extensions/mermaid-chat-features/package.json b/extensions/mermaid-chat-features/package.json
index 592f55d370259..f7f74fb4ed396 100644
--- a/extensions/mermaid-chat-features/package.json
+++ b/extensions/mermaid-chat-features/package.json
@@ -84,6 +84,9 @@
         "viewType": "vscode.chat-mermaid-features.chatOutputItem",
         "mimeTypes": [
           "text/vnd.mermaid"
+        ],
+        "codeBlockLanguageIdentifiers": [
+          "mermaid"
         ]
       }
     ],
diff --git a/src/vs/workbench/api/browser/mainThreadChatOutputRenderer.ts b/src/vs/workbench/api/browser/mainThreadChatOutputRenderer.ts
index 08d5b729a2109..0f7f57ab656e3 100644
--- a/src/vs/workbench/api/browser/mainThreadChatOutputRenderer.ts
+++ b/src/vs/workbench/api/browser/mainThreadChatOutputRenderer.ts
@@ -7,6 +7,7 @@ import { VSBuffer } from '../../../base/common/buffer.js';
 import { Disposable, IDisposable } from '../../../base/common/lifecycle.js';
 import { URI, UriComponents } from '../../../base/common/uri.js';
 import { ExtensionIdentifier } from '../../../platform/extensions/common/extensions.js';
+import { ILogService } from '../../../platform/log/common/log.js';
 import { IChatOutputRendererService } from '../../contrib/chat/browser/chatOutputItemRenderer.js';
 import { IExtHostContext } from '../../services/extensions/common/extHostCustomers.js';
 import { ExtHostChatOutputRendererShape, ExtHostContext, MainThreadChatOutputRendererShape } from '../common/extHost.protocol.js';
@@ -24,6 +25,7 @@ export class MainThreadChatOutputRenderer extends Disposable implements MainThre
 		extHostContext: IExtHostContext,
 		private readonly _mainThreadWebview: MainThreadWebviews,
 		@IChatOutputRendererService private readonly _rendererService: IChatOutputRendererService,
+		@ILogService private readonly _logService: ILogService,
 	) {
 		super();
 		this._proxy = extHostContext.getProxy(ExtHostContext.ExtHostChatOutputRenderer);
@@ -37,22 +39,30 @@ export class MainThreadChatOutputRenderer extends Disposable implements MainThre
 	}
 
 	$registerChatOutputRenderer(viewType: string, extensionId: ExtensionIdentifier, extensionLocation: UriComponents): void {
-		this._rendererService.registerRenderer(viewType, {
-			renderOutputPart: async (mime, data, webview, token) => {
+		const existingRegistration = this.registeredRenderers.get(viewType);
+		if (existingRegistration) {
+			this._logService.warn(`Re-registering chat output renderer for view type '${viewType}' from extension '${extensionId.value}'.`);
+			existingRegistration.dispose();
+		}
+
+		const disposable = this._rendererService.registerRenderer(viewType, {
+			renderOutputPart: async (mime, data, webview, context, token) => {
 				const webviewHandle = `chat-output-${++this._webviewHandlePool}`;
 
 				this._mainThreadWebview.addWebview(webviewHandle, webview, {
 					serializeBuffersForPostMessage: true,
 				});
 
-				return this._proxy.$renderChatOutput(viewType, mime, VSBuffer.wrap(data), webviewHandle, token);
+				return this._proxy.$renderChatOutput(viewType, mime, VSBuffer.wrap(data), webviewHandle, context, token);
 			},
 		}, {
 			extension: { id: extensionId, location: URI.revive(extensionLocation) }
 		});
+		this.registeredRenderers.set(viewType, disposable);
 	}
 
 	$unregisterChatOutputRenderer(viewType: string): void {
 		this.registeredRenderers.get(viewType)?.dispose();
+		this.registeredRenderers.delete(viewType);
 	}
 }
diff --git a/src/vs/workbench/api/common/extHost.protocol.ts b/src/vs/workbench/api/common/extHost.protocol.ts
index 0d26fe9292661..e5742089332a9 100644
--- a/src/vs/workbench/api/common/extHost.protocol.ts
+++ b/src/vs/workbench/api/common/extHost.protocol.ts
@@ -1894,8 +1894,14 @@ export interface MainThreadChatOutputRendererShape extends IDisposable {
 	$unregisterChatOutputRenderer(viewType: string): void;
 }
 
+export interface IChatOutputRenderContextDto {
+	readonly codeBlockContext?: {
+		readonly languageIdentifier: string;
+	};
+}
+
 export interface ExtHostChatOutputRendererShape {
-	$renderChatOutput(viewType: string, mime: string, valueData: VSBuffer, webviewHandle: string, token: CancellationToken): Promise<void>;
+	$renderChatOutput(viewType: string, mime: string, valueData: VSBuffer, webviewHandle: string, context: IChatOutputRenderContextDto, token: CancellationToken): Promise<void>;
 }
 
 export interface MainThreadProfileContentHandlersShape {
diff --git a/src/vs/workbench/api/common/extHostChatOutputRenderer.ts b/src/vs/workbench/api/common/extHostChatOutputRenderer.ts
index 444faf9e46f9b..8ecaa31b69a5e 100644
--- a/src/vs/workbench/api/common/extHostChatOutputRenderer.ts
+++ b/src/vs/workbench/api/common/extHostChatOutputRenderer.ts
@@ -5,7 +5,7 @@
 
 import type * as vscode from 'vscode';
 import { CancellationToken } from '../../../base/common/cancellation.js';
-import { ExtHostChatOutputRendererShape, IMainContext, MainContext, MainThreadChatOutputRendererShape } from './extHost.protocol.js';
+import { ExtHostChatOutputRendererShape, type IChatOutputRenderContextDto, IMainContext, MainContext, MainThreadChatOutputRendererShape } from './extHost.protocol.js';
 import { Disposable } from './extHostTypes.js';
 import { ExtHostWebviews } from './extHostWebview.js';
 import { IExtensionDescription } from '../../../platform/extensions/common/extensions.js';
@@ -41,7 +41,7 @@ export class ExtHostChatOutputRenderer implements ExtHostChatOutputRendererShape
 		});
 	}
 
-	async $renderChatOutput(viewType: string, mime: string, valueData: VSBuffer, webviewHandle: string, token: CancellationToken): Promise<void> {
+	async $renderChatOutput(viewType: string, mime: string, valueData: VSBuffer, webviewHandle: string, context: IChatOutputRenderContextDto, token: CancellationToken): Promise<void> {
 		const entry = this._renderers.get(viewType);
 		if (!entry) {
 			throw new Error(`No chat output renderer registered for: ${viewType}`);
@@ -52,6 +52,6 @@ export class ExtHostChatOutputRenderer implements ExtHostChatOutputRendererShape
 			webview: extHostWebview,
 			onDidDispose: extHostWebview._onDidDispose,
 		});
-		return entry.renderer.renderChatOutput(Object.freeze({ mime, value: valueData.buffer }), chatOutputWebview, {}, token);
+		return entry.renderer.renderChatOutput(Object.freeze({ mime, value: valueData.buffer }), chatOutputWebview, Object.freeze(context), token);
 	}
 }
diff --git a/src/vs/workbench/contrib/chat/browser/chatOutputItemRenderer.ts b/src/vs/workbench/contrib/chat/browser/chatOutputItemRenderer.ts
index 9e150d731cc18..68500fd673737 100644
--- a/src/vs/workbench/contrib/chat/browser/chatOutputItemRenderer.ts
+++ b/src/vs/workbench/contrib/chat/browser/chatOutputItemRenderer.ts
@@ -12,6 +12,7 @@ import { Emitter, Event } from '../../../../base/common/event.js';
 import { IJSONSchema, TypeFromJsonSchema } from '../../../../base/common/jsonSchema.js';
 import { Disposable, DisposableStore, IDisposable } from '../../../../base/common/lifecycle.js';
 import { autorun } from '../../../../base/common/observable.js';
+import { equalsIgnoreCase } from '../../../../base/common/strings.js';
 import { URI } from '../../../../base/common/uri.js';
 import { generateUuid } from '../../../../base/common/uuid.js';
 import * as nls from '../../../../nls.js';
@@ -23,7 +24,13 @@ import { IExtensionService, isProposedApiEnabled } from '../../../services/exten
 import { ExtensionsRegistry, IExtensionPointUser } from '../../../services/extensions/common/extensionsRegistry.js';
 
 export interface IChatOutputItemRenderer {
-	renderOutputPart(mime: string, data: Uint8Array, webview: IWebview, token: CancellationToken): Promise<void>;
+	renderOutputPart(mime: string, data: Uint8Array, webview: IWebview, context: IChatOutputRenderContext, token: CancellationToken): Promise<void>;
+}
+
+export interface IChatOutputRenderContext {
+	readonly codeBlockContext?: {
+		readonly languageIdentifier: string;
+	};
 }
 
 interface RegisterOptions {
@@ -38,9 +45,13 @@ export const IChatOutputRendererService = createDecorator<IChatOutputRendererSer
 export interface IChatOutputRendererService {
 	readonly _serviceBrand: undefined;
 
-	registerRenderer(mime: string, renderer: IChatOutputItemRenderer, options: RegisterOptions): IDisposable;
+	registerRenderer(viewType: string, renderer: IChatOutputItemRenderer, options: RegisterOptions): IDisposable;
+
+	hasCodeBlockRenderer(languageIdentifier: string): boolean;
 
 	renderOutputPart(mime: string, data: Uint8Array, parent: HTMLElement, webviewOptions: RenderOutputPartWebviewOptions, token: CancellationToken): Promise<RenderedOutputPart>;
+
+	renderCodeBlock(languageIdentifier: string, data: Uint8Array, parent: HTMLElement, webviewOptions: RenderOutputPartWebviewOptions, token: CancellationToken): Promise<RenderedOutputPart>;
 }
 
 export interface RenderedOutputPart extends IDisposable {
@@ -51,10 +62,15 @@ export interface RenderedOutputPart extends IDisposable {
 }
 
 interface RenderOutputPartWebviewOptions {
+	readonly title?: string;
 	readonly origin?: string;
 	readonly webviewState?: string;
 }
 
+interface ContributionEntry {
+	readonly mimes: readonly string[];
+	readonly codeBlockLanguageIdentifiers: readonly string[];
+}
 
 interface RendererEntry {
 	readonly viewType: string;
@@ -65,9 +81,7 @@ interface RendererEntry {
 export class ChatOutputRendererService extends Disposable implements IChatOutputRendererService {
 	_serviceBrand: undefined;
 
-	private readonly _contributions = new Map</*viewType*/ string, {
-		readonly mimes: readonly string[];
-	}>();
+	private readonly _contributions = new Map</*viewType*/ string, ContributionEntry>();
 
 	private readonly _renderers = new Map</*viewType*/ string, RendererEntry>();
 
@@ -92,8 +106,12 @@ export class ChatOutputRendererService extends Disposable implements IChatOutput
 		};
 	}
 
+	hasCodeBlockRenderer(languageIdentifier: string): boolean {
+		return Array.from(this._contributions.values()).some(value => value.codeBlockLanguageIdentifiers.some(identifier => equalsIgnoreCase(identifier, languageIdentifier)));
+	}
+
 	async renderOutputPart(mime: string, data: Uint8Array, parent: HTMLElement, webviewOptions: RenderOutputPartWebviewOptions, token: CancellationToken): Promise<RenderedOutputPart> {
-		const rendererData = await this.getRenderer(mime, token);
+		const rendererData = await this.getRendererForMime(mime, token);
 		if (token.isCancellationRequested) {
 			throw new CancellationError();
 		}
@@ -102,10 +120,28 @@ export class ChatOutputRendererService extends Disposable implements IChatOutput
 			throw new Error(`No renderer registered found for mime type: ${mime}`);
 		}
 
+		return this.doRenderOutputPart(rendererData, mime, data, {}, parent, webviewOptions, token);
+	}
+
+	async renderCodeBlock(languageIdentifier: string, data: Uint8Array, parent: HTMLElement, webviewOptions: RenderOutputPartWebviewOptions, token: CancellationToken): Promise<RenderedOutputPart> {
+		const rendererData = await this.getRendererForCodeBlock(languageIdentifier, token);
+		if (token.isCancellationRequested) {
+			throw new CancellationError();
+		}
+
+		if (!rendererData) {
+			throw new Error(`No renderer registered found for code block language identifier: ${languageIdentifier}`);
+		}
+
+		return this.doRenderOutputPart(rendererData, 'text/x-vscode-chat-code-block', data, { codeBlockContext: { languageIdentifier } }, parent, webviewOptions, token);
+	}
+
+	private async doRenderOutputPart(rendererData: RendererEntry, mime: string, data: Uint8Array, context: IChatOutputRenderContext, parent: HTMLElement, webviewOptions: RenderOutputPartWebviewOptions, token: CancellationToken): Promise<RenderedOutputPart> {
+
 		const store = new DisposableStore();
 
 		const webview = store.add(this._webviewService.createWebviewElement({
-			title: '',
+			title: webviewOptions.title ?? '',
 			origin: webviewOptions.origin ?? generateUuid(),
 			providedViewType: rendererData.viewType,
 			options: {
@@ -132,7 +168,7 @@ export class ChatOutputRendererService extends Disposable implements IChatOutput
 		}
 
 		webview.mountTo(parent, getWindow(parent));
-		await rendererData.renderer.renderOutputPart(mime, data, webview, token);
+		await rendererData.renderer.renderOutputPart(mime, data, webview, context, token);
 
 		return {
 			get webview() { return webview; },
@@ -146,10 +182,18 @@ export class ChatOutputRendererService extends Disposable implements IChatOutput
 		};
 	}
 
-	private async getRenderer(mime: string, token: CancellationToken): Promise<RendererEntry | undefined> {
+	private async getRendererForMime(mime: string, token: CancellationToken): Promise<RendererEntry | undefined> {
+		return this.getRenderer(value => value.mimes.some(m => matchesMimeType(m, [mime])), token);
+	}
+
+	private async getRendererForCodeBlock(languageIdentifier: string, token: CancellationToken): Promise<RendererEntry | undefined> {
+		return this.getRenderer(value => value.codeBlockLanguageIdentifiers.some(identifier => equalsIgnoreCase(identifier, languageIdentifier)), token);
+	}
+
+	private async getRenderer(matches: (value: ContributionEntry) => boolean, token: CancellationToken): Promise<RendererEntry | undefined> {
 		await raceCancellationError(this._extensionService.whenInstalledExtensionsRegistered(), token);
 		for (const [id, value] of this._contributions) {
-			if (value.mimes.some(m => matchesMimeType(m, [mime]))) {
+			if (matches(value)) {
 				await raceCancellationError(this._extensionService.activateByEvent(`onChatOutputRenderer:${id}`), token);
 				const rendererData = this._renderers.get(id);
 				if (rendererData) {
@@ -174,8 +218,16 @@ export class ChatOutputRendererService extends Disposable implements IChatOutput
 					continue;
 				}
 
+				const mimeTypes = contribution.mimeTypes ?? [];
+				const codeBlockLanguageIdentifiers = contribution.codeBlockLanguageIdentifiers ?? [];
+				if (!mimeTypes.length && !codeBlockLanguageIdentifiers.length) {
+					extension.collector.error(`Chat output renderer with view type '${contribution.viewType}' must specify at least one mime type or code block language identifier`);
+					continue;
+				}
+
 				this._contributions.set(contribution.viewType, {
-					mimes: contribution.mimeTypes,
+					mimes: mimeTypes,
+					codeBlockLanguageIdentifiers,
 				});
 			}
 		}
@@ -185,7 +237,7 @@ export class ChatOutputRendererService extends Disposable implements IChatOutput
 const chatOutputRendererContributionSchema = {
 	type: 'object',
 	additionalProperties: false,
-	required: ['viewType', 'mimeTypes'],
+	required: ['viewType'],
 	properties: {
 		viewType: {
 			type: 'string',
@@ -194,6 +246,15 @@ const chatOutputRendererContributionSchema = {
 		mimeTypes: {
 			type: 'array',
 			description: nls.localize('chatOutputRenderer.mimeTypes', 'MIME types that this renderer can handle'),
+			uniqueItems: true,
+			items: {
+				type: 'string'
+			}
+		},
+		codeBlockLanguageIdentifiers: {
+			type: 'array',
+			description: nls.localize('chatOutputRenderer.codeBlockLanguageIdentifiers', 'Code block language identifiers that this renderer can handle'),
+			uniqueItems: true,
 			items: {
 				type: 'string'
 			}
@@ -211,7 +272,7 @@ const chatOutputRenderContributionPoint = ExtensionsRegistry.registerExtensionPo
 		}
 	},
 	jsonSchema: {
-		description: nls.localize('vscode.extension.contributes.chatOutputRenderer', 'Contributes a renderer for specific MIME types in chat outputs'),
+		description: nls.localize('vscode.extension.contributes.chatOutputRenderer', 'Contributes a renderer for specific MIME types and code block language identifiers in chat outputs'),
 		type: 'array',
 		items: chatOutputRendererContributionSchema,
 	}
diff --git a/src/vs/workbench/contrib/chat/browser/widget/chatContentParts/chatMarkdownContentPart.ts b/src/vs/workbench/contrib/chat/browser/widget/chatContentParts/chatMarkdownContentPart.ts
index 056d9177a3100..934b268c1cbb1 100644
--- a/src/vs/workbench/contrib/chat/browser/widget/chatContentParts/chatMarkdownContentPart.ts
+++ b/src/vs/workbench/contrib/chat/browser/widget/chatContentParts/chatMarkdownContentPart.ts
@@ -13,7 +13,9 @@ import { DomScrollableElement } from '../../../../../../base/browser/ui/scrollba
 import { wrapTablesWithScrollable } from './chatMarkdownTableScrolling.js';
 import { coalesce } from '../../../../../../base/common/arrays.js';
 import { findLast } from '../../../../../../base/common/arraysFind.js';
+import { CancellationTokenSource } from '../../../../../../base/common/cancellation.js';
 import { Codicon } from '../../../../../../base/common/codicons.js';
+import { isCancellationError } from '../../../../../../base/common/errors.js';
 import { MarkdownString } from '../../../../../../base/common/htmlContent.js';
 import { Lazy } from '../../../../../../base/common/lazy.js';
 import { Disposable, DisposableStore, dispose, IDisposable, MutableDisposable } from '../../../../../../base/common/lifecycle.js';
@@ -23,6 +25,7 @@ import { ScrollbarVisibility } from '../../../../../../base/common/scrollable.js
 import { ThemeIcon } from '../../../../../../base/common/themables.js';
 import { isEqual } from '../../../../../../base/common/resources.js';
 import { URI } from '../../../../../../base/common/uri.js';
+import { generateUuid } from '../../../../../../base/common/uuid.js';
 import { Range } from '../../../../../../editor/common/core/range.js';
 import { isLocation, type SymbolTag } from '../../../../../../editor/common/languages.js';
 import { ILanguageService } from '../../../../../../editor/common/languages/language.js';
@@ -51,7 +54,8 @@ import { IChatProgressRenderableResponseContent } from '../../../common/model/ch
 import { IChatContentInlineReference, IChatMarkdownContent, IChatService, IChatUndoStop } from '../../../common/chatService/chatService.js';
 import { isRequestVM, isResponseVM } from '../../../common/model/chatViewModel.js';
 import { ChatConfiguration } from '../../../common/constants.js';
-import { IChatCodeBlockInfo } from '../../chat.js';
+import { IChatCodeBlockInfo, IChatWidgetService } from '../../chat.js';
+import { IChatOutputRendererService, type RenderedOutputPart } from '../../chatOutputItemRenderer.js';
 import { allowedChatMarkdownHtmlTags } from '../chatContentMarkdownRenderer.js';
 import { IMarkdownDiffBlockData, MarkdownDiffBlockPart, parseUnifiedDiff } from './chatDiffBlockPart.js';
 import { ChatEditingActionContext } from '../../chatEditing/chatEditingActions.js';
@@ -62,6 +66,7 @@ import { IDisposableReference } from './chatCollections.js';
 import { EditorPool } from './chatContentCodePools.js';
 import { IChatContentPart, IChatContentPartRenderContext } from './chatContentParts.js';
 import { ChatExtensionsContentPart } from './chatExtensionsContentPart.js';
+import { ChatProgressSubPart } from './chatProgressContentPart.js';
 import { IncrementalDOMMorpher } from './chatIncrementalRendering/chatIncrementalRendering.js';
 import './media/chatMarkdownPart.css';
 
@@ -102,7 +107,7 @@ export class ChatMarkdownContentPart extends Disposable implements IChatContentP
 	 */
 	readonly onDidChangeDiff: Event<IEditSessionDiffStats> = this._onDidChangeDiff.event;
 
-	private readonly allRefs: IDisposableReference<CodeBlockPart | CollapsedCodeBlock | MarkdownDiffBlockPart>[] = [];
+	private readonly allRefs: IDisposableReference<CodeBlockPart | ChatOutputCodeBlockPart | CollapsedCodeBlock | MarkdownDiffBlockPart>[] = [];
 
 	private readonly _codeblocks: IMarkdownPartCodeBlockInfo[] = [];
 	public get codeblocks(): IChatCodeBlockInfo[] {
@@ -128,6 +133,7 @@ export class ChatMarkdownContentPart extends Disposable implements IChatContentP
 		@IConfigurationService configurationService: IConfigurationService,
 		@IInstantiationService private readonly instantiationService: IInstantiationService,
 		@IAiEditTelemetryService private readonly aiEditTelemetryService: IAiEditTelemetryService,
+		@IChatOutputRendererService private readonly chatOutputRendererService: IChatOutputRendererService,
 	) {
 		super();
 
@@ -218,7 +224,11 @@ export class ChatMarkdownContentPart extends Disposable implements IChatContentP
 				fillInIncompleteTokens,
 				codeBlockRendererSync: (languageId, text, raw) => {
 					const isCodeBlockComplete = !isResponseVM(context.element) || context.element.isComplete || !raw || codeblockHasClosingBackticks(raw);
-					if ((!text || (text.startsWith('<vscode_codeblock_uri') && !text.includes('\n'))) && !isCodeBlockComplete) {
+					const hasChatOutputRenderer = !!languageId
+						&& this.chatOutputRendererService.hasCodeBlockRenderer(languageId);
+					if ((!text || (text.startsWith('<vscode_codeblock_uri') && !text.includes('\n')))
+						&& !isCodeBlockComplete
+						&& !hasChatOutputRenderer) {
 						const hideEmptyCodeblock = $('div');
 						hideEmptyCodeblock.style.display = 'none';
 						return hideEmptyCodeblock;
@@ -287,6 +297,23 @@ export class ChatMarkdownContentPart extends Disposable implements IChatContentP
 					};
 
 					if (element.isCompleteAddedRequest || !codemapperUri || !isEdit) {
+						if (hasChatOutputRenderer) {
+							const ref = this.renderChatOutputCodeBlock(languageId, codeBlockText, globalIndex, context, isCodeBlockComplete);
+							this._codeblocks.push({
+								...baseCodeBlockInfo,
+								codemapperUri: codeBlockInfo.codemapperUri,
+								isStreamingEdit: false,
+								get uri() {
+									return undefined;
+								},
+								focus() {
+									ref.object.focus();
+								},
+							});
+							store.add(ref);
+							return ref.object.element;
+						}
+
 						const ref = this.renderCodeBlock(codeBlockInfo, currentWidth);
 						this._codeblocks.push({
 							...baseCodeBlockInfo,
@@ -423,6 +450,31 @@ export class ChatMarkdownContentPart extends Disposable implements IChatContentP
 		return ref;
 	}
 
+	private renderChatOutputCodeBlock(
+		identifier: string,
+		text: string,
+		codeBlockIndex: number,
+		context: IChatContentPartRenderContext,
+		isComplete: boolean
+	): IDisposableReference<ChatOutputCodeBlockPart> {
+		const codeBlock = this.instantiationService.createInstance(
+			ChatOutputCodeBlockPart,
+			identifier,
+			text,
+			codeBlockIndex,
+			context,
+			isComplete,
+			() => this._onDidChangeHeight.fire()
+		);
+		const ref: IDisposableReference<ChatOutputCodeBlockPart> = {
+			object: codeBlock,
+			isStale: () => false,
+			dispose: () => codeBlock.dispose()
+		};
+		this.allRefs.push(ref);
+		return ref;
+	}
+
 	private fireAggregatedDiff(): void {
 		let totalAdded = 0;
 		let totalRemoved = 0;
@@ -516,6 +568,8 @@ export class ChatMarkdownContentPart extends Disposable implements IChatContentP
 		this.allRefs.forEach((ref, index) => {
 			if (ref.object instanceof CodeBlockPart) {
 				ref.object.layout(width);
+			} else if (ref.object instanceof ChatOutputCodeBlockPart) {
+				ref.object.layout(width);
 			} else if (ref.object instanceof MarkdownDiffBlockPart) {
 				ref.object.layout(width);
 			} else if (ref.object instanceof CollapsedCodeBlock) {
@@ -531,7 +585,7 @@ export class ChatMarkdownContentPart extends Disposable implements IChatContentP
 
 	onDidRemount(): void {
 		for (const ref of this.allRefs) {
-			if (ref.object instanceof CodeBlockPart) {
+			if (ref.object instanceof CodeBlockPart || ref.object instanceof ChatOutputCodeBlockPart) {
 				ref.object.onDidRemount();
 			}
 		}
@@ -613,6 +667,126 @@ export function codeblockHasClosingBackticks(str: string): boolean {
 	return !!str.match(/\n```+$/);
 }
 
+class ChatOutputCodeBlockPart extends Disposable {
+
+	readonly element: HTMLElement;
+
+	private readonly _disposeCts = this._register(new CancellationTokenSource());
+	private readonly _renderedOutputPart = this._register(new MutableDisposable<RenderedOutputPart>());
+
+	constructor(
+		identifier: string,
+		text: string,
+		codeBlockIndex: number,
+		private readonly context: IChatContentPartRenderContext,
+		isComplete: boolean,
+		private readonly onDidChangeHeight: () => void,
+		@IInstantiationService private readonly instantiationService: IInstantiationService,
+		@IChatOutputRendererService private readonly chatOutputRendererService: IChatOutputRendererService,
+		@IChatWidgetService private readonly chatWidgetService: IChatWidgetService,
+	) {
+		super();
+
+		const title = localize('chat.renderedCodeBlockLabel', "Rendered code block {0}", codeBlockIndex + 1);
+		this.element = $('.interactive-result-code-block.chat-output-code-block.tool-output-part');
+		this.element.tabIndex = -1;
+		this.element.ariaLabel = title;
+
+		const parent = $('.webview-output');
+		parent.style.maxHeight = '80vh';
+		parent.style.minHeight = '38px';
+		this.element.appendChild(parent);
+
+		const progressMessage = $('span');
+		progressMessage.textContent = localize('chat.codeBlockOutputRendering', "Rendering code block...");
+		const progressPart = this._register(this.instantiationService.createInstance(ChatProgressSubPart, progressMessage, ThemeIcon.modify(Codicon.loading, 'spin'), undefined));
+		parent.appendChild(progressPart.domNode);
+		if (!isComplete) {
+			this.onDidChangeHeight();
+			return;
+		}
+
+		this.chatOutputRendererService.renderCodeBlock(identifier, new TextEncoder().encode(text), parent, { origin: generateUuid(), title }, this._disposeCts.token).then(renderedItem => {
+			if (this._disposeCts.token.isCancellationRequested) {
+				renderedItem.dispose();
+				return;
+			}
+
+			this._renderedOutputPart.value = renderedItem;
+			progressPart.domNode.remove();
+			parent.style.minHeight = '';
+			this.onDidChangeHeight();
+
+			this._register(renderedItem.onDidChangeHeight(() => this.onDidChangeHeight()));
+			this._register(renderedItem.webview.onDidWheel(e => {
+				this.chatWidgetService.getWidgetBySessionResource(this.context.element.sessionResource)?.delegateScrollFromMouseWheelEvent({
+					...e,
+					preventDefault: () => { },
+					stopPropagation: () => { }
+				});
+			}));
+
+			this._register(this.context.onDidChangeVisibility(visible => {
+				if (visible) {
+					renderedItem.reinitialize();
+				}
+			}));
+		}, error => {
+			if (isCancellationError(error)) {
+				return;
+			}
+
+			console.error('Error rendering chat code block:', error);
+			progressPart.domNode.replaceWith(this.renderError(error));
+			parent.style.minHeight = '';
+			this.onDidChangeHeight();
+		});
+	}
+
+	override dispose(): void {
+		this._disposeCts.dispose(true);
+		super.dispose();
+	}
+
+	layout(width: number): void {
+		this.element.style.maxWidth = `${width}px`;
+	}
+
+	onDidRemount(): void {
+		this._renderedOutputPart.value?.reinitialize();
+	}
+
+	focus(): void {
+		const webview = this._renderedOutputPart.value?.webview;
+		if (webview) {
+			webview.focus();
+		} else {
+			this.element.focus();
+		}
+	}
+
+	private renderError(error: Error): HTMLElement {
+		const errorNode = $('.output-error');
+
+		const errorHeaderNode = $('.output-error-header');
+		dom.append(errorNode, errorHeaderNode);
+
+		const iconElement = $('div');
+		iconElement.classList.add(...ThemeIcon.asClassNameArray(Codicon.error));
+		errorHeaderNode.append(iconElement);
+
+		const errorTitleNode = $('.output-error-title');
+		errorTitleNode.textContent = localize('chat.codeBlockOutputError', "Error rendering the code block");
+		errorHeaderNode.append(errorTitleNode);
+
+		const errorMessageNode = $('.output-error-details');
+		errorMessageNode.textContent = error?.message || String(error);
+		errorNode.append(errorMessageNode);
+
+		return errorNode;
+	}
+}
+
 export class CollapsedCodeBlock extends Disposable {
 
 	readonly element: HTMLElement;
diff --git a/src/vs/workbench/contrib/chat/test/browser/widget/chatContentParts/chatMarkdownContentPart.test.ts b/src/vs/workbench/contrib/chat/test/browser/widget/chatContentParts/chatMarkdownContentPart.test.ts
index 36d47ed7be88e..e9b7070cec8ea 100644
--- a/src/vs/workbench/contrib/chat/test/browser/widget/chatContentParts/chatMarkdownContentPart.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/widget/chatContentParts/chatMarkdownContentPart.test.ts
@@ -22,6 +22,7 @@ import { IChatContentPartRenderContext } from '../../../../browser/widget/chatCo
 import { ChatMarkdownContentPart } from '../../../../browser/widget/chatContentParts/chatMarkdownContentPart.js';
 import { EditorPool, DiffEditorPool } from '../../../../browser/widget/chatContentParts/chatContentCodePools.js';
 import { CodeBlockPart, ICodeBlockData } from '../../../../browser/widget/chatContentParts/codeBlockPart.js';
+import { IChatOutputRendererService, type RenderedOutputPart } from '../../../../browser/chatOutputItemRenderer.js';
 import { IChatResponseViewModel } from '../../../../common/model/chatViewModel.js';
 import { IChatContentInlineReference } from '../../../../common/chatService/chatService.js';
 import { ChatConfiguration } from '../../../../common/constants.js';
@@ -39,6 +40,7 @@ suite('ChatMarkdownContentPart', () => {
 
 	/** Data captured from each CodeBlockPart.render() call */
 	const renderedCodeBlocks: ICodeBlockData[] = [];
+	const renderedCodeBlockOutputs: { identifier: string; text: string }[] = [];
 
 	function createMockEditorPool(): EditorPool {
 		return {
@@ -132,6 +134,7 @@ suite('ChatMarkdownContentPart', () => {
 		disposables = store.add(new DisposableStore());
 		instantiationService = workbenchInstantiationService(undefined, disposables);
 		renderedCodeBlocks.length = 0;
+		renderedCodeBlockOutputs.length = 0;
 
 		// Seed configuration values needed by ChatEditorOptions
 		const configService = instantiationService.get(IConfigurationService) as TestConfigurationService;
@@ -171,6 +174,25 @@ suite('ChatMarkdownContentPart', () => {
 			handleCodeRejected: () => { },
 		});
 
+		instantiationService.stub(IChatOutputRendererService, {
+			_serviceBrand: undefined,
+			registerRenderer: () => ({ dispose: () => { } }),
+			hasCodeBlockRenderer: identifier => identifier.toLowerCase() === 'mermaid',
+			renderOutputPart: async () => { throw new Error('Unexpected output render'); },
+			renderCodeBlock: async (identifier, data) => {
+				renderedCodeBlockOutputs.push({ identifier, text: new TextDecoder().decode(data) });
+				return {
+					webview: {
+						focus: () => { },
+						onDidWheel: Event.None,
+					} as RenderedOutputPart['webview'],
+					onDidChangeHeight: Event.None,
+					reinitialize: () => { },
+					dispose: () => { },
+				};
+			},
+		});
+
 		// Stub view descriptor service
 		instantiationService.stub(IViewDescriptorService, {
 			onDidChangeLocation: Event.None,
@@ -209,6 +231,48 @@ suite('ChatMarkdownContentPart', () => {
 		assert.strictEqual(renderedCodeBlocks[0].languageId, 'javascript');
 	});
 
+	test('renders complete code block with contributed chat output renderer', () => {
+		const part = createMarkdownPart('```mermaid\ngraph TD\n```');
+
+		assert.strictEqual(part.codeblocks.length, 1);
+		assert.strictEqual(part.codeblocks[0].languageId, 'mermaid');
+		assert.strictEqual(renderedCodeBlocks.length, 0);
+		assert.deepStrictEqual(renderedCodeBlockOutputs, [{ identifier: 'mermaid', text: 'graph TD' }]);
+		assert.ok(part.domNode.querySelector('.chat-output-code-block'));
+	});
+
+	test('renders complete code block with contributed chat output renderer case-insensitively', () => {
+		const part = createMarkdownPart('```Mermaid\ngraph TD\n```');
+
+		assert.strictEqual(part.codeblocks.length, 1);
+		assert.strictEqual(part.codeblocks[0].languageId, 'Mermaid');
+		assert.strictEqual(renderedCodeBlocks.length, 0);
+		assert.deepStrictEqual(renderedCodeBlockOutputs, [{ identifier: 'Mermaid', text: 'graph TD' }]);
+		assert.ok(part.domNode.querySelector('.chat-output-code-block'));
+	});
+
+	test('does not render initial incomplete code fence', () => {
+		const ctx = createRenderContext(false);
+		const part = createMarkdownPart('```', ctx);
+
+		assert.strictEqual(part.codeblocks.length, 0);
+		assert.strictEqual(renderedCodeBlocks.length, 0);
+		assert.strictEqual(renderedCodeBlockOutputs.length, 0);
+		assert.strictEqual(part.domNode.querySelector('.interactive-result-code-block'), null);
+	});
+
+	test('shows pending chat output renderer for incomplete code block', () => {
+		const ctx = createRenderContext(false);
+		const part = createMarkdownPart('```mermaid\ngraph TD', ctx);
+
+		assert.strictEqual(renderedCodeBlockOutputs.length, 0);
+		assert.strictEqual(renderedCodeBlocks.length, 0);
+		assert.strictEqual(part.codeblocks.length, 1);
+		assert.strictEqual(part.codeblocks[0].languageId, 'mermaid');
+		assert.ok(part.domNode.querySelector('.chat-output-code-block'));
+		assert.ok(part.domNode.textContent?.includes('Rendering code block'));
+	});
+
 	test('renders multiple code blocks with correct indices', () => {
 		const part = createMarkdownPart(
 			'Some text\n```python\nprint("a")\n```\nMore text\n```typescript\nconst x = 1;\n```'
diff --git a/src/vscode-dts/vscode.proposed.chatOutputRenderer.d.ts b/src/vscode-dts/vscode.proposed.chatOutputRenderer.d.ts
index 839ce0bb41ad7..16a26a43bed02 100644
--- a/src/vscode-dts/vscode.proposed.chatOutputRenderer.d.ts
+++ b/src/vscode-dts/vscode.proposed.chatOutputRenderer.d.ts
@@ -59,6 +59,25 @@ declare module 'vscode' {
 		readonly onDidDispose: Event<void>;
 	}
 
+	/**
+	 * Additional context for rendering chat output.
+	 */
+	export interface ChatOutputRenderContext {
+		/**
+		 * Context when a code block is being rendered.
+		 *
+		 * This is set when a renderer contributed through `chatOutputRenderers` renders
+		 * a completed fenced code block whose identifier matches one of the contributed
+		 * `codeBlockLanguageIdentifiers`.
+		 */
+		readonly codeBlockContext?: {
+			/**
+			 * The language identifier of the code block being rendered.
+			 */
+			readonly languageIdentifier: string;
+		};
+	}
+
 	export interface ChatOutputRenderer {
 		/**
 		 * Given an output, render it into the provided webview.
@@ -72,7 +91,7 @@ declare module 'vscode' {
 		 *
 		 * @returns A promise that resolves when the webview has been initialized and is ready to be presented to the user.
 		 */
-		renderChatOutput(data: ChatOutputDataItem, webview: ChatOutputWebview, ctx: {}, token: CancellationToken): Thenable<void>;
+		renderChatOutput(data: ChatOutputDataItem, webview: ChatOutputWebview, ctx: ChatOutputRenderContext, token: CancellationToken): Thenable<void>;
 	}
 
 	export namespace chat {
@@ -84,10 +103,11 @@ declare module 'vscode' {
 		 *
 		 * ```json
 		 * "contributes": {
-		 *   "chatOutputRenderer": [
+		 *   "chatOutputRenderers": [
 		 *     {
 		 *       "viewType": "myExt.myChatOutputRenderer",
-		 *       "mimeTypes": ["application/your-mime-type"]
+		 *       "mimeTypes": ["application/your-mime-type"],
+		 *       "codeBlockLanguageIdentifiers": ["mermaid"]
 		 *     }
 		 *   ]
 		 * }

From 06115d9e8fbc5bfae917509a73cf7d394ae1f2d9 Mon Sep 17 00:00:00 2001
From: Matt Bierner <12821956+mjbvz@users.noreply.github.com>
Date: Tue, 12 May 2026 16:33:15 -0700
Subject: [PATCH 05/27] Add improved markdown front matter rendering

Fixes #316140

Let's try with `table` as the default initially but we can switch to `hide` is we prefer
---
 .../media/markdown.css                        |  44 ++++
 .../package-lock.json                         |  24 ++-
 .../markdown-language-features/package.json   |  20 +-
 .../package.nls.json                          |   4 +
 .../extensions/yamlPreamble/yamlPreamble.ts   | 200 ++++++++++++++++++
 .../src/markdownEngine.ts                     |  16 +-
 .../src/preview/previewConfig.ts              |   2 +
 .../src/test/engine.test.ts                   |  69 ++++++
 .../src/typings/ref.d.ts                      |   6 -
 .../src/util/dom.ts                           |   9 +
 10 files changed, 365 insertions(+), 29 deletions(-)
 create mode 100644 extensions/markdown-language-features/src/extensions/yamlPreamble/yamlPreamble.ts
 delete mode 100644 extensions/markdown-language-features/src/typings/ref.d.ts

diff --git a/extensions/markdown-language-features/media/markdown.css b/extensions/markdown-language-features/media/markdown.css
index 5a02627888dd7..53179e10f816a 100644
--- a/extensions/markdown-language-features/media/markdown.css
+++ b/extensions/markdown-language-features/media/markdown.css
@@ -453,3 +453,47 @@ pre {
 .vscode-dark td {
 	border-color: rgba(255, 255, 255, 0.18);
 }
+
+/* Front matter rendering */
+table.frontmatter {
+	margin-bottom: 16px;
+	border-collapse: collapse;
+}
+
+table.frontmatter th,
+table.frontmatter td {
+	padding: 6px 13px;
+	border: 1px solid var(--vscode-widget-border, rgba(127, 127, 127, 0.35));
+	text-align: left;
+	vertical-align: top;
+}
+
+table.frontmatter th {
+	font-weight: 600;
+	white-space: nowrap;
+}
+
+table.frontmatter td > ul {
+	margin: 0;
+	padding-left: 1.2em;
+}
+
+pre.frontmatter {
+	margin-bottom: 16px;
+}
+
+.frontmatter-error {
+	margin-bottom: 16px;
+	padding: 8px 13px;
+	border-left: 4px solid var(--vscode-editorError-foreground, #f48771);
+	background: var(--vscode-inputValidation-errorBackground, rgba(244, 135, 113, 0.1));
+	color: var(--vscode-editorError-foreground, #f48771);
+}
+
+.frontmatter-error pre {
+	margin: 6px 0 0;
+	white-space: pre-wrap;
+	color: inherit;
+	background: transparent;
+	padding: 0;
+}
diff --git a/extensions/markdown-language-features/package-lock.json b/extensions/markdown-language-features/package-lock.json
index 15fed36ad6319..15c5980ba3864 100644
--- a/extensions/markdown-language-features/package-lock.json
+++ b/extensions/markdown-language-features/package-lock.json
@@ -13,14 +13,14 @@
         "dompurify": "^3.4.1",
         "highlight.js": "^11.8.0",
         "markdown-it": "^12.3.2",
-        "markdown-it-front-matter": "^0.2.4",
         "morphdom": "^2.7.7",
         "picomatch": "^2.3.2",
         "punycode": "^2.3.1",
         "vscode-languageclient": "^8.0.2",
         "vscode-languageserver-textdocument": "^1.0.11",
         "vscode-markdown-languageserver": "0.5.0-alpha.15",
-        "vscode-uri": "^3.0.3"
+        "vscode-uri": "^3.0.3",
+        "yaml": "^2.8.3"
       },
       "devDependencies": {
         "@types/dompurify": "^3.0.5",
@@ -494,11 +494,6 @@
         "markdown-it": "bin/markdown-it.js"
       }
     },
-    "node_modules/markdown-it-front-matter": {
-      "version": "0.2.4",
-      "resolved": "https://registry.npmjs.org/markdown-it-front-matter/-/markdown-it-front-matter-0.2.4.tgz",
-      "integrity": "sha512-25GUs0yjS2hLl8zAemVndeEzThB1p42yxuDEKbd4JlL3jiz+jsm6e56Ya8B0VREOkNxLYB4TTwaoPJ3ElMmW+w=="
-    },
     "node_modules/markdown-it/node_modules/entities": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/entities/-/entities-2.1.0.tgz",
@@ -730,6 +725,21 @@
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/yallist/-/yallist-4.0.0.tgz",
       "integrity": "sha512-3wdGidZyq5PB084XLES5TpOSRA3wjXAlIWMhum2kRcv/41Sn2emQ0dycQW4uZXLejwKvg6EsvbdlVL+FYEct7A=="
+    },
+    "node_modules/yaml": {
+      "version": "2.9.0",
+      "resolved": "https://registry.npmjs.org/yaml/-/yaml-2.9.0.tgz",
+      "integrity": "sha512-2AvhNX3mb8zd6Zy7INTtSpl1F15HW6Wnqj0srWlkKLcpYl/gMIMJiyuGq2KeI2YFxUPjdlB+3Lc10seMLtL4cA==",
+      "license": "ISC",
+      "bin": {
+        "yaml": "bin.mjs"
+      },
+      "engines": {
+        "node": ">= 14.6"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/eemeli"
+      }
     }
   }
 }
diff --git a/extensions/markdown-language-features/package.json b/extensions/markdown-language-features/package.json
index cd2e94bbb48b7..d8232ce221927 100644
--- a/extensions/markdown-language-features/package.json
+++ b/extensions/markdown-language-features/package.json
@@ -771,6 +771,22 @@
               "%configuration.markdown.preview.openMarkdownLinks.inPreview%",
               "%configuration.markdown.preview.openMarkdownLinks.inEditor%"
             ]
+          },
+          "markdown.preview.frontMatter": {
+            "type": "string",
+            "default": "table",
+            "scope": "resource",
+            "markdownDescription": "%configuration.markdown.preview.frontMatter.description%",
+            "enum": [
+              "hide",
+              "codeBlock",
+              "table"
+            ],
+            "enumDescriptions": [
+              "%configuration.markdown.preview.frontMatter.hide%",
+              "%configuration.markdown.preview.frontMatter.codeBlock%",
+              "%configuration.markdown.preview.frontMatter.table%"
+            ]
           }
         }
       },
@@ -860,14 +876,14 @@
     "dompurify": "^3.4.1",
     "highlight.js": "^11.8.0",
     "markdown-it": "^12.3.2",
-    "markdown-it-front-matter": "^0.2.4",
     "morphdom": "^2.7.7",
     "picomatch": "^2.3.2",
     "punycode": "^2.3.1",
     "vscode-languageclient": "^8.0.2",
     "vscode-languageserver-textdocument": "^1.0.11",
     "vscode-markdown-languageserver": "0.5.0-alpha.15",
-    "vscode-uri": "^3.0.3"
+    "vscode-uri": "^3.0.3",
+    "yaml": "^2.8.3"
   },
   "devDependencies": {
     "@types/dompurify": "^3.0.5",
diff --git a/extensions/markdown-language-features/package.nls.json b/extensions/markdown-language-features/package.nls.json
index dc8f65048c998..b4ac4c7f58a78 100644
--- a/extensions/markdown-language-features/package.nls.json
+++ b/extensions/markdown-language-features/package.nls.json
@@ -37,6 +37,10 @@
 	"configuration.markdown.preview.openMarkdownLinks.description": "Controls how links to other Markdown files in the Markdown preview should be opened.",
 	"configuration.markdown.preview.openMarkdownLinks.inEditor": "Try to open links in the editor.",
 	"configuration.markdown.preview.openMarkdownLinks.inPreview": "Try to open links in the Markdown preview.",
+	"configuration.markdown.preview.frontMatter.description": "Controls how YAML front matter (delimited by `---`) at the start of a Markdown file is rendered in the preview.",
+	"configuration.markdown.preview.frontMatter.hide": "Do not render front matter.",
+	"configuration.markdown.preview.frontMatter.codeBlock": "Render front matter as a code block.",
+	"configuration.markdown.preview.frontMatter.table": "Render front matter as a table of keys and values.",
 	"configuration.markdown.links.openLocation.description": "Controls where links in Markdown files should be opened.",
 	"configuration.markdown.links.openLocation.currentGroup": "Open links in the active editor group.",
 	"configuration.markdown.links.openLocation.beside": "Open links beside the active editor.",
diff --git a/extensions/markdown-language-features/src/extensions/yamlPreamble/yamlPreamble.ts b/extensions/markdown-language-features/src/extensions/yamlPreamble/yamlPreamble.ts
new file mode 100644
index 0000000000000..417386e232e40
--- /dev/null
+++ b/extensions/markdown-language-features/src/extensions/yamlPreamble/yamlPreamble.ts
@@ -0,0 +1,200 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import type MarkdownIt from 'markdown-it';
+import type Token from 'markdown-it/lib/token.mjs';
+import * as vscode from 'vscode';
+import * as yaml from 'yaml';
+import { escapeHtml } from '../../util/dom';
+
+export type FrontMatterRenderStyle = 'hide' | 'codeBlock' | 'table';
+
+const FRONT_MATTER_TOKEN = 'front_matter';
+const MARKER = '---';
+
+interface IFrontMatterMeta {
+	readonly content: string;
+}
+
+/**
+ * Extends a `markdown-it` instance with parsing and rendering support for YAML
+ * front matter at the start of a Markdown document.
+ *
+ * Front matter is delimited by lines containing only `---`. How (or whether) the parsed
+ * front matter is rendered in the preview is controlled by the `markdown.preview.frontMatter`
+ * setting.
+ */
+export function extendMarkdownIt(md: MarkdownIt): MarkdownIt {
+	md.block.ruler.before('fence', FRONT_MATTER_TOKEN, frontMatterRule, {
+		alt: ['paragraph', 'reference', 'blockquote', 'list']
+	});
+
+	md.renderer.rules[FRONT_MATTER_TOKEN] = renderFrontMatter;
+
+	return md;
+}
+
+const frontMatterRule = (state: MarkdownIt.StateBlock, startLine: number, endLine: number, silent: boolean): boolean => {
+	if (startLine !== 0 || state.tShift[startLine] !== 0) {
+		return false;
+	}
+
+	const firstLineStart = state.bMarks[startLine];
+	const firstLineEnd = state.eMarks[startLine];
+	const firstLine = state.src.slice(firstLineStart, firstLineEnd).replace(/\s+$/, '');
+
+	if (firstLine !== MARKER) {
+		return false;
+	}
+
+	let nextLine = startLine + 1;
+	let foundEnd = false;
+	for (; nextLine < endLine; nextLine++) {
+		if (state.tShift[nextLine] !== 0) {
+			continue;
+		}
+		const lineStart = state.bMarks[nextLine];
+		const lineEnd = state.eMarks[nextLine];
+		const line = state.src.slice(lineStart, lineEnd).replace(/\s+$/, '');
+		if (line === MARKER) {
+			foundEnd = true;
+			break;
+		}
+	}
+
+	if (!foundEnd) {
+		return false;
+	}
+
+	if (silent) {
+		return true;
+	}
+
+	const contentStart = state.bMarks[startLine + 1];
+	const contentEnd = state.bMarks[nextLine];
+	const rawContent = state.src.slice(contentStart, contentEnd).replace(/\n$/, '');
+
+	const token = state.push(FRONT_MATTER_TOKEN, '', 0);
+	token.block = true;
+	token.hidden = false;
+	token.markup = MARKER;
+	token.map = [startLine, nextLine + 1];
+	const meta: IFrontMatterMeta = { content: rawContent };
+	token.meta = meta;
+
+	state.line = nextLine + 1;
+	return true;
+};
+
+function renderFrontMatter(tokens: Token[], idx: number, options: MarkdownIt.Options, env: unknown): string {
+	const meta = tokens[idx].meta as IFrontMatterMeta | undefined;
+	if (!meta) {
+		return '';
+	}
+
+	const currentDocument = (env as { currentDocument?: vscode.Uri } | undefined)?.currentDocument;
+	const style = getFrontMatterRenderStyle(currentDocument);
+
+	switch (style) {
+		case 'codeBlock':
+			return renderAsCodeBlock(meta, options);
+		case 'table':
+			return renderAsTable(meta);
+		case 'hide':
+		default:
+			return '';
+	}
+}
+
+function getFrontMatterRenderStyle(resource: vscode.Uri | undefined): FrontMatterRenderStyle {
+	const config = vscode.workspace.getConfiguration('markdown', resource ?? null);
+	const value = config.get<string>('preview.frontMatter', 'table');
+	switch (value) {
+		case 'codeBlock':
+		case 'table':
+		case 'hide':
+			return value;
+		default:
+			return 'table';
+	}
+}
+
+function renderAsCodeBlock(meta: IFrontMatterMeta, options: MarkdownIt.Options): string {
+	let highlighted: string | undefined;
+	if (typeof options.highlight === 'function') {
+		try {
+			highlighted = options.highlight(meta.content, 'yaml', '') || undefined;
+		} catch {
+			highlighted = undefined;
+		}
+	}
+	if (highlighted?.startsWith('<pre')) {
+		return highlighted + '\n';
+	}
+	const body = highlighted ?? escapeHtml(meta.content);
+	return `<pre class="frontmatter hljs"><code class="language-yaml">${body}</code></pre>\n`;
+}
+
+function renderAsTable(meta: IFrontMatterMeta): string {
+	const result = parseEntries(meta);
+	if (result.error !== undefined) {
+		return renderError(result.error);
+	}
+	if (!result.entries.length) {
+		return '';
+	}
+	const rows = result.entries.map(([key, value]) =>
+		`<tr><th>${escapeHtml(key)}</th><td>${formatValueHtml(value)}</td></tr>`
+	).join('');
+	return `<table class="frontmatter"><tbody>${rows}</tbody></table>\n`;
+}
+
+function renderError(message: string): string {
+	const label = vscode.l10n.t('Failed to parse front matter');
+	return `<div class="frontmatter-error" role="alert"><strong>${escapeHtml(label)}</strong><pre>${escapeHtml(message)}</pre></div>\n`;
+}
+
+interface IParseResult {
+	readonly entries: readonly [string, unknown][];
+	readonly error?: string;
+}
+
+function parseEntries(meta: IFrontMatterMeta): IParseResult {
+	try {
+		const parsed = yaml.parse(meta.content);
+		if (parsed === null || parsed === undefined) {
+			return { entries: [] };
+		}
+		if (typeof parsed !== 'object' || Array.isArray(parsed)) {
+			return { entries: [['', parsed]] };
+		}
+		return { entries: Object.entries(parsed as Record<string, unknown>) };
+	} catch (e) {
+		return { entries: [], error: e instanceof Error ? e.message : String(e) };
+	}
+}
+
+function formatValueHtml(value: unknown): string {
+	if (value === null || value === undefined) {
+		return '';
+	}
+	if (Array.isArray(value)) {
+		if (!value.length) {
+			return '';
+		}
+		return `<ul>${value.map(v => `<li>${formatValueHtml(v)}</li>`).join('')}</ul>`;
+	}
+	if (typeof value === 'object') {
+		return `<code>${escapeHtml(yaml.stringify(value).trimEnd())}</code>`;
+	}
+	return escapeHtml(formatScalar(value));
+}
+
+function formatScalar(value: unknown): string {
+	if (value instanceof Date) {
+		return value.toISOString();
+	}
+	return String(value);
+}
diff --git a/extensions/markdown-language-features/src/markdownEngine.ts b/extensions/markdown-language-features/src/markdownEngine.ts
index 4ed3186c3807d..d1aacf9a8b171 100644
--- a/extensions/markdown-language-features/src/markdownEngine.ts
+++ b/extensions/markdown-language-features/src/markdownEngine.ts
@@ -5,6 +5,7 @@
 
 import type MarkdownIt from 'markdown-it';
 import * as vscode from 'vscode';
+import { extendMarkdownIt as extendMarkdownItWithFrontMatter } from './extensions/yamlPreamble/yamlPreamble';
 import { ILogger } from './logging';
 import { MarkdownContributionProvider } from './markdownExtensions';
 import { MarkdownPreviewConfiguration } from './preview/previewConfig';
@@ -144,20 +145,7 @@ export class MarkdownItEngine implements IMdParser {
 					}
 				}
 
-				const frontMatterPlugin = await import('markdown-it-front-matter');
-				// Extract rules from front matter plugin and apply at a lower precedence
-				let fontMatterRule: any;
-				frontMatterPlugin.default({
-					block: {
-						ruler: {
-							before: (_id: any, _id2: any, rule: any) => { fontMatterRule = rule; }
-						}
-					}
-				}, () => { /* noop */ });
-
-				md.block.ruler.before('fence', 'front_matter', fontMatterRule, {
-					alt: ['paragraph', 'reference', 'blockquote', 'list']
-				});
+				md = extendMarkdownItWithFrontMatter(md);
 
 				this.#addImageRenderer(md);
 				this.#addFencedRenderer(md);
diff --git a/extensions/markdown-language-features/src/preview/previewConfig.ts b/extensions/markdown-language-features/src/preview/previewConfig.ts
index ac240b97eb71c..821bbb7840595 100644
--- a/extensions/markdown-language-features/src/preview/previewConfig.ts
+++ b/extensions/markdown-language-features/src/preview/previewConfig.ts
@@ -17,6 +17,7 @@ export class MarkdownPreviewConfiguration {
 	public readonly previewLineBreaks: boolean;
 	public readonly previewLinkify: boolean;
 	public readonly previewTypographer: boolean;
+	public readonly previewFrontMatter: string;
 
 	public readonly doubleClickToSwitchToEditor: boolean;
 	public readonly scrollEditorWithPreview: boolean;
@@ -46,6 +47,7 @@ export class MarkdownPreviewConfiguration {
 		this.previewLineBreaks = !!markdownConfig.get<boolean>('preview.breaks', false);
 		this.previewLinkify = !!markdownConfig.get<boolean>('preview.linkify', true);
 		this.previewTypographer = !!markdownConfig.get<boolean>('preview.typographer', false);
+		this.previewFrontMatter = markdownConfig.get<string>('preview.frontMatter', 'table');
 
 		this.doubleClickToSwitchToEditor = !!markdownConfig.get<boolean>('preview.doubleClickToSwitchToEditor', true);
 		this.markEditorSelection = !!markdownConfig.get<boolean>('preview.markEditorSelection', true);
diff --git a/extensions/markdown-language-features/src/test/engine.test.ts b/extensions/markdown-language-features/src/test/engine.test.ts
index cd3322f704ae9..b9f980e19fe43 100644
--- a/extensions/markdown-language-features/src/test/engine.test.ts
+++ b/extensions/markdown-language-features/src/test/engine.test.ts
@@ -49,4 +49,73 @@ suite('markdown.engine', () => {
 			assert.deepStrictEqual([...result.containingImages], ['img.png', 'http://example.org/img.png', './img2.png']);
 		});
 	});
+
+	suite('front-matter', () => {
+		const settingName = 'preview.frontMatter';
+		const input = '---\ntitle: Hello\n---\n\n# World';
+
+		let originalValue: string | undefined;
+
+		suiteSetup(() => {
+			originalValue = vscode.workspace.getConfiguration('markdown').inspect<string>(settingName)?.globalValue;
+		});
+
+		suiteTeardown(async () => {
+			await vscode.workspace.getConfiguration('markdown').update(settingName, originalValue, vscode.ConfigurationTarget.Global);
+		});
+
+		async function setStyle(style: string) {
+			await vscode.workspace.getConfiguration('markdown').update(settingName, style, vscode.ConfigurationTarget.Global);
+		}
+
+		test('Hides front matter when style is "hide"', async () => {
+			await setStyle('hide');
+			const engine = createNewMarkdownEngine();
+			assert.strictEqual(
+				(await engine.render(input)).html,
+				'<h1 data-line="4" class="code-line" dir="auto" id="world">World</h1>\n'
+			);
+		});
+
+		test('Renders front matter as a code block when style is "codeBlock"', async () => {
+			await setStyle('codeBlock');
+			const engine = createNewMarkdownEngine();
+			const html = (await engine.render(input)).html;
+			assert.match(html, /<pre[^>]*class="[^"]*frontmatter[^"]*"[^>]*>[\s\S]*<\/pre>/);
+			assert.ok(html.includes('title'), `Expected front matter content to be rendered. Got: ${html}`);
+			assert.ok(html.includes('<h1 data-line="4"'), `Expected body to render after front matter. Got: ${html}`);
+		});
+
+		test('Renders front matter as a table when style is "table"', async () => {
+			await setStyle('table');
+			const engine = createNewMarkdownEngine();
+			assert.strictEqual(
+				(await engine.render(input)).html,
+				'<table class="frontmatter"><tbody><tr><th>title</th><td>Hello</td></tr></tbody></table>\n'
+				+ '<h1 data-line="4" class="code-line" dir="auto" id="world">World</h1>\n'
+			);
+		});
+
+		test('Shows an error when front matter has invalid YAML', async () => {
+			await setStyle('table');
+			const engine = createNewMarkdownEngine();
+			const html = (await engine.render('---\nfoo: [unclosed\n---\n\n# Body')).html;
+			assert.match(html, /<div class="frontmatter-error"[\s\S]*<\/div>/);
+			assert.ok(html.includes('<h1 data-line="4"'), `Expected body to render after error. Got: ${html}`);
+		});
+
+		test('Ignores front matter that is not at the start of the document', async () => {
+			await setStyle('table');
+			const engine = createNewMarkdownEngine();
+			const html = (await engine.render('# World\n\n---\ntitle: Hello\n---')).html;
+			assert.ok(!html.includes('<table class="frontmatter">'), `Expected no front matter table. Got: ${html}`);
+		});
+
+		test('Ignores front matter without a closing delimiter', async () => {
+			await setStyle('table');
+			const engine = createNewMarkdownEngine();
+			const html = (await engine.render('---\ntitle: Hello\n\n# World')).html;
+			assert.ok(!html.includes('<table class="frontmatter">'), `Expected no front matter table. Got: ${html}`);
+		});
+	});
 });
diff --git a/extensions/markdown-language-features/src/typings/ref.d.ts b/extensions/markdown-language-features/src/typings/ref.d.ts
deleted file mode 100644
index d16ef8dc39701..0000000000000
--- a/extensions/markdown-language-features/src/typings/ref.d.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-/*---------------------------------------------------------------------------------------------
- *  Copyright (c) Microsoft Corporation. All rights reserved.
- *  Licensed under the MIT License. See License.txt in the project root for license information.
- *--------------------------------------------------------------------------------------------*/
-
-declare module 'markdown-it-front-matter';
diff --git a/extensions/markdown-language-features/src/util/dom.ts b/extensions/markdown-language-features/src/util/dom.ts
index 16c825c68ff57..68cd47cdbf16c 100644
--- a/extensions/markdown-language-features/src/util/dom.ts
+++ b/extensions/markdown-language-features/src/util/dom.ts
@@ -11,3 +11,12 @@ export function escapeAttribute(value: string | vscode.Uri): string {
 		.replace(/'/g, '&#39;');
 }
 
+export function escapeHtml(text: string): string {
+	return text
+		.replace(/&/g, '&amp;')
+		.replace(/</g, '&lt;')
+		.replace(/>/g, '&gt;')
+		.replace(/"/g, '&quot;')
+		.replace(/'/g, '&#39;');
+}
+

From 5284fa1d910b15717acf6283eb774c661e4b2034 Mon Sep 17 00:00:00 2001
From: Sandeep Somavarapu <sasomava@microsoft.com>
Date: Wed, 13 May 2026 14:40:25 +0200
Subject: [PATCH 06/27] sessions: use delegation for active session and force
 replace on session swap (#316229)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Replace the spread-based `IActiveSession` construction with an
`ActiveSession` class that delegates all `ISession` property accesses
to the underlying session object. This keeps the active session in sync
with live session state instead of holding a stale shallow copy.

When a session is replaced via `onDidReplaceSession`, pass
`force: true` to `setActiveSession` so the active session is always
fully rebuilt — even when the session ID remains the same.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../browser/sessionsManagementService.ts      | 48 ++++++++++++++++---
 1 file changed, 41 insertions(+), 7 deletions(-)

diff --git a/src/vs/sessions/services/sessions/browser/sessionsManagementService.ts b/src/vs/sessions/services/sessions/browser/sessionsManagementService.ts
index 4331eaaead95f..829e4ac43bba5 100644
--- a/src/vs/sessions/services/sessions/browser/sessionsManagementService.ts
+++ b/src/vs/sessions/services/sessions/browser/sessionsManagementService.ts
@@ -142,7 +142,7 @@ class SessionsManagementService extends Disposable implements ISessionsManagemen
 
 	private onDidReplaceSession(from: ISession, to: ISession): void {
 		if (this._activeSession.get()?.sessionId === from.sessionId) {
-			this.setActiveSession(to);
+			this.setActiveSession(to, /* force */ true);
 		}
 		// Always fire the change event so the SessionsList refreshes even when
 		// the user navigated to a different session while the new one was
@@ -430,9 +430,9 @@ class SessionsManagementService extends Disposable implements ISessionsManagemen
 		this._isNewChatInSessionContext.set(true);
 	}
 
-	private setActiveSession(session: ISession | undefined): void {
+	private setActiveSession(session: ISession | undefined, force?: boolean): void {
 		const previousSession = this._activeSession.get();
-		if (previousSession?.sessionId === session?.sessionId) {
+		if (!force && previousSession?.sessionId === session?.sessionId) {
 			return;
 		}
 
@@ -478,10 +478,7 @@ class SessionsManagementService extends Disposable implements ISessionsManagemen
 			// Create the active chat observable
 			const activeChatObs = observableValue<IChat>(`activeChat-${session.sessionId}`, initialChat);
 			this._activeChatObservable = activeChatObs;
-			const activeSession: IActiveSession = {
-				...session,
-				activeChat: activeChatObs,
-			};
+			const activeSession = new ActiveSession(session, activeChatObs);
 
 			this._activeSession.set(activeSession, undefined);
 
@@ -705,6 +702,43 @@ class SessionsManagementService extends Disposable implements ISessionsManagemen
 	}
 }
 
+/**
+ * Wraps an {@link ISession} with an active chat observable to form an
+ * {@link IActiveSession}. Delegates all {@link ISession} property accesses
+ * to the wrapped session so the active session always reflects the latest
+ * session state without a stale shallow copy.
+ */
+class ActiveSession implements IActiveSession {
+	constructor(
+		private readonly _session: ISession,
+		readonly activeChat: IObservable<IChat>,
+	) { }
+
+	get sessionId() { return this._session.sessionId; }
+	get resource() { return this._session.resource; }
+	get providerId() { return this._session.providerId; }
+	get sessionType() { return this._session.sessionType; }
+	get icon() { return this._session.icon; }
+	get createdAt() { return this._session.createdAt; }
+	get workspace() { return this._session.workspace; }
+	get title() { return this._session.title; }
+	get updatedAt() { return this._session.updatedAt; }
+	get status() { return this._session.status; }
+	get changes() { return this._session.changes; }
+	get changesets() { return this._session.changesets; }
+	get modelId() { return this._session.modelId; }
+	get mode() { return this._session.mode; }
+	get loading() { return this._session.loading; }
+	get isArchived() { return this._session.isArchived; }
+	get isRead() { return this._session.isRead; }
+	get description() { return this._session.description; }
+	get lastTurnEnd() { return this._session.lastTurnEnd; }
+	get chats() { return this._session.chats; }
+	get mainChat() { return this._session.mainChat; }
+	get capabilities() { return this._session.capabilities; }
+	get deduplicationKey() { return this._session.deduplicationKey; }
+}
+
 registerSingleton(ISessionsManagementService, SessionsManagementService, InstantiationType.Delayed);
 
 /**

From 22aa13fb9a97e49a5f58d2f0736b1410b2908f8a Mon Sep 17 00:00:00 2001
From: Logan Ramos <lramos15@gmail.com>
Date: Wed, 13 May 2026 08:41:04 -0400
Subject: [PATCH 07/27] Remove deprecated token fields (#316230)

---
 .../src/platform/authentication/common/copilotToken.ts   | 9 +--------
 .../authentication/test/node/copilotToken.spec.ts        | 3 ---
 2 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/extensions/copilot/src/platform/authentication/common/copilotToken.ts b/extensions/copilot/src/platform/authentication/common/copilotToken.ts
index ae8968f27d406..f20de388488f4 100644
--- a/extensions/copilot/src/platform/authentication/common/copilotToken.ts
+++ b/extensions/copilot/src/platform/authentication/common/copilotToken.ts
@@ -345,8 +345,6 @@ export interface TokenEnvelope {
 	codesearch: boolean;
 	/** Whether content exclusion (.copilotignore) is enabled. */
 	copilotignore_enabled: boolean;
-	/** Whether VS Code electron fetcher v2 is enabled. */
-	vsc_electron_fetcher_v2: boolean;
 
 	// Consent settings
 	/** 'enabled', 'disabled', or 'unconfigured' for public code suggestions. */
@@ -365,8 +363,6 @@ export interface TokenEnvelope {
 	limited_user_reset_date?: number | null;
 	/** Organization tracking IDs if user has org access. */
 	organization_list?: string[];
-	/** Notification to show in editor on successful token retrieval. */
-	user_notification?: NotificationEnvelope;
 }
 
 /**
@@ -419,7 +415,6 @@ const tokenEnvelopeValidator = vObj({
 	code_review_enabled: vBoolean(),
 	codesearch: vBoolean(),
 	copilotignore_enabled: vBoolean(),
-	vsc_electron_fetcher_v2: vBoolean(),
 	public_suggestions: vEnum('enabled', 'disabled', 'unconfigured'),
 	telemetry: vEnum('enabled', 'disabled'),
 	endpoints: vObj({
@@ -434,8 +429,7 @@ const tokenEnvelopeValidator = vObj({
 		completions: vRequired(vNumber()),
 	})),
 	limited_user_reset_date: vNullable(vNumber()),
-	organization_list: vArray(vString()),
-	user_notification: notificationEnvelopeValidator,
+	organization_list: vArray(vString())
 });
 
 const standardErrorEnvelopeValidator = vObj({
@@ -565,7 +559,6 @@ export function createTestExtendedTokenInfo(overrides?: Partial<ExtendedTokenInf
 		code_review_enabled: false,
 		codesearch: false,
 		copilotignore_enabled: false,
-		vsc_electron_fetcher_v2: false,
 		// Consent settings
 		public_suggestions: 'enabled',
 		telemetry: 'enabled',
diff --git a/extensions/copilot/src/platform/authentication/test/node/copilotToken.spec.ts b/extensions/copilot/src/platform/authentication/test/node/copilotToken.spec.ts
index 5125592d57835..bb72c1ef8e67c 100644
--- a/extensions/copilot/src/platform/authentication/test/node/copilotToken.spec.ts
+++ b/extensions/copilot/src/platform/authentication/test/node/copilotToken.spec.ts
@@ -261,7 +261,6 @@ describe('Token envelope validators', function () {
 			code_review_enabled: false,
 			codesearch: false,
 			copilotignore_enabled: false,
-			vsc_electron_fetcher_v2: false,
 			public_suggestions: 'enabled',
 			telemetry: 'enabled',
 		};
@@ -281,7 +280,6 @@ describe('Token envelope validators', function () {
 			code_review_enabled: false,
 			codesearch: false,
 			copilotignore_enabled: false,
-			vsc_electron_fetcher_v2: false,
 			public_suggestions: 'enabled',
 			telemetry: 'enabled',
 			limited_user_quotas: null,
@@ -347,7 +345,6 @@ describe('Token envelope validators', function () {
 				code_review_enabled: false,
 				codesearch: false,
 				copilotignore_enabled: false,
-				vsc_electron_fetcher_v2: false,
 				public_suggestions: 'enabled',
 				telemetry: 'enabled',
 			};

From d4a82f0b337a6b06299ac1f936dffebc08e17100 Mon Sep 17 00:00:00 2001
From: Sandeep Somavarapu <sasomava@microsoft.com>
Date: Wed, 13 May 2026 14:41:42 +0200
Subject: [PATCH 08/27] sessions: fix customization harness layer violation by
 using session types (#316231)

Replace the eslint-disabled import of LOCAL_SESSION_ENABLED_SETTING from
the providers layer with ISessionsManagementService.getAllSessionTypes().
The local harness is now registered when any provider offers a session
type with id 'local', and removed when it disappears.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../browser/customizationHarnessService.ts    | 40 +++++++++++--------
 1 file changed, 23 insertions(+), 17 deletions(-)

diff --git a/src/vs/sessions/contrib/chat/browser/customizationHarnessService.ts b/src/vs/sessions/contrib/chat/browser/customizationHarnessService.ts
index 57201bedf435a..258927e65adab 100644
--- a/src/vs/sessions/contrib/chat/browser/customizationHarnessService.ts
+++ b/src/vs/sessions/contrib/chat/browser/customizationHarnessService.ts
@@ -4,20 +4,25 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { IDisposable } from '../../../../base/common/lifecycle.js';
-import { IConfigurationService } from '../../../../platform/configuration/common/configuration.js';
 import { CustomizationHarnessServiceBase, createVSCodeHarnessDescriptor, IHarnessDescriptor } from '../../../../workbench/contrib/chat/common/customizationHarnessService.js';
 import { IPromptsService, PromptsStorage } from '../../../../workbench/contrib/chat/common/promptSyntax/service/promptsService.js';
 import { BUILTIN_STORAGE } from '../common/builtinPromptsStorage.js';
 import { SessionType } from '../../../../workbench/contrib/chat/common/chatSessionsService.js';
-// eslint-disable-next-line local/code-import-patterns
-import { LOCAL_SESSION_ENABLED_SETTING } from '../../providers/copilotChatSessions/browser/copilotChatSessionsProvider.js';
+import { ISessionsManagementService } from '../../../services/sessions/common/sessionsManagement.js';
+
+/**
+ * The session type that supports local harness customization.
+ * Hardcoded for now — ideally providers would declare harness support explicitly.
+ */
+const LOCAL_HARNESS_SESSION_TYPE = 'local';
 
 /**
  * Sessions-window override of the customization harness service.
  *
- * The Local harness is registered when the `sessions.chat.localAgent.enabled`
- * setting is true (the default). When the setting is toggled, the harness is
- * dynamically added or removed so that the Customizations editor reflects the
+ * The Local harness is registered when a provider offers a session type
+ * matching {@link LOCAL_HARNESS_SESSION_TYPE}. When providers are added or
+ * removed (or their session types change), the harness is dynamically
+ * added or removed so that the Customizations editor reflects the
  * current state.
  *
  * The Copilot CLI extension provides its harness (with `itemProvider`) via
@@ -30,7 +35,7 @@ export class SessionsCustomizationHarnessService extends CustomizationHarnessSer
 
 	constructor(
 		@IPromptsService promptsService: IPromptsService,
-		@IConfigurationService configurationService: IConfigurationService,
+		@ISessionsManagementService private readonly sessionsManagementService: ISessionsManagementService,
 	) {
 		const localExtras = [PromptsStorage.extension, BUILTIN_STORAGE];
 		const localHarness = createVSCodeHarnessDescriptor(localExtras);
@@ -41,17 +46,18 @@ export class SessionsCustomizationHarnessService extends CustomizationHarnessSer
 			promptsService,
 		);
 
-		// Register the local harness dynamically so it can be toggled
-		// when the `sessions.chat.localAgent.enabled` setting changes.
-		if (configurationService.getValue<boolean>(LOCAL_SESSION_ENABLED_SETTING) !== false) {
-			this._localHarnessRegistration = this.registerExternalHarness(localHarness);
-		}
+		const sync = () => this._syncLocalHarness(localHarness, this._hasLocalSessionType());
 
-		configurationService.onDidChangeConfiguration(e => {
-			if (e.affectsConfiguration(LOCAL_SESSION_ENABLED_SETTING)) {
-				this._syncLocalHarness(localHarness, configurationService.getValue<boolean>(LOCAL_SESSION_ENABLED_SETTING) !== false);
-			}
-		});
+		this.sessionsManagementService.onDidChangeSessionTypes(sync);
+
+		// Initial sync
+		sync();
+	}
+
+	private _hasLocalSessionType(): boolean {
+		return this.sessionsManagementService.getAllSessionTypes().some(
+			t => t.id === LOCAL_HARNESS_SESSION_TYPE
+		);
 	}
 
 	private _syncLocalHarness(descriptor: IHarnessDescriptor, enabled: boolean): void {

From 40f8fa49a29a6ead521f88916dddbee16466751b Mon Sep 17 00:00:00 2001
From: BeniBenj <besimmonds@microsoft.com>
Date: Wed, 13 May 2026 15:10:27 +0200
Subject: [PATCH 09/27] fix window controls in agents window

---
 src/vs/sessions/browser/parts/titlebarPart.ts |  6 +-
 .../electron-browser/parts/titlebarPart.ts    | 90 ++++++++++++++++++-
 2 files changed, 89 insertions(+), 7 deletions(-)

diff --git a/src/vs/sessions/browser/parts/titlebarPart.ts b/src/vs/sessions/browser/parts/titlebarPart.ts
index 3a4735f9961bf..d0f492902f056 100644
--- a/src/vs/sessions/browser/parts/titlebarPart.ts
+++ b/src/vs/sessions/browser/parts/titlebarPart.ts
@@ -75,8 +75,8 @@ export class TitlebarPart extends Part implements ITitlebarPart {
 
 	//#endregion
 
-	private rootContainer!: HTMLElement;
-	private windowControlsContainer: HTMLElement | undefined;
+	protected rootContainer!: HTMLElement;
+	protected windowControlsContainer: HTMLElement | undefined;
 
 	private leftContent!: HTMLElement;
 	private leftToolbarContainer!: HTMLElement;
@@ -271,7 +271,7 @@ export class TitlebarPart extends Part implements ITitlebarPart {
 		}
 	}
 
-	private onContextMenu(e: MouseEvent): void {
+	protected onContextMenu(e: MouseEvent): void {
 		const event = new StandardMouseEvent(getWindow(this.element), e);
 		this.contextMenuService.showContextMenu({
 			getAnchor: () => event,
diff --git a/src/vs/sessions/electron-browser/parts/titlebarPart.ts b/src/vs/sessions/electron-browser/parts/titlebarPart.ts
index 638f04ce2c2fa..ae368d1bf22c1 100644
--- a/src/vs/sessions/electron-browser/parts/titlebarPart.ts
+++ b/src/vs/sessions/electron-browser/parts/titlebarPart.ts
@@ -4,7 +4,10 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { getZoomFactor } from '../../../base/browser/browser.js';
-import { getWindow, getWindowId } from '../../../base/browser/dom.js';
+import { $, addDisposableListener, append, EventType, getWindow, getWindowId, hide, show } from '../../../base/browser/dom.js';
+import { Codicon } from '../../../base/common/codicons.js';
+import { Event } from '../../../base/common/event.js';
+import { ThemeIcon } from '../../../base/common/themables.js';
 import { IConfigurationService } from '../../../platform/configuration/common/configuration.js';
 import { IContextKeyService } from '../../../platform/contextkey/common/contextkey.js';
 import { IContextMenuService } from '../../../platform/contextview/browser/contextView.js';
@@ -13,7 +16,7 @@ import { INativeHostService } from '../../../platform/native/common/native.js';
 import { IProductService } from '../../../platform/product/common/productService.js';
 import { IStorageService } from '../../../platform/storage/common/storage.js';
 import { IThemeService } from '../../../platform/theme/common/themeService.js';
-import { useWindowControlsOverlay } from '../../../platform/window/common/window.js';
+import { hasNativeTitlebar, useWindowControlsOverlay } from '../../../platform/window/common/window.js';
 import { IsWindowAlwaysOnTopContext } from '../../../workbench/common/contextkeys.js';
 import { IHostService } from '../../../workbench/services/host/browser/host.js';
 import { IWorkbenchLayoutService, Parts } from '../../../workbench/services/layout/browser/layoutService.js';
@@ -21,11 +24,14 @@ import { IAuxiliaryTitlebarPart } from '../../../workbench/browser/parts/titleba
 import { IEditorGroupsContainer } from '../../../workbench/services/editor/common/editorGroupsService.js';
 import { CodeWindow, mainWindow } from '../../../base/browser/window.js';
 import { TitlebarPart, TitleService } from '../../browser/parts/titlebarPart.js';
-import { isMacintosh } from '../../../base/common/platform.js';
+import { isMacintosh, isWindows } from '../../../base/common/platform.js';
 import { localize } from '../../../nls.js';
 
 export class NativeTitlebarPart extends TitlebarPart {
 
+	private maxRestoreControl: HTMLElement | undefined;
+	private resizer: HTMLElement | undefined;
+
 	private cachedWindowControlStyles: { bgColor: string; fgColor: string } | undefined;
 	private cachedWindowControlHeight: number | undefined;
 
@@ -64,7 +70,83 @@ export class NativeTitlebarPart extends TitlebarPart {
 		}
 		window.document.title = agentsTitle;
 
-		return super.createContentArea(parent);
+		const result = super.createContentArea(parent);
+		const targetWindow = getWindow(parent);
+		const targetWindowId = getWindowId(targetWindow);
+
+		// Custom Window Controls (Native Windows/Linux) when window.controlsStyle is "custom"
+		if (
+			!hasNativeTitlebar(this.configurationService) &&		// not for native title bars
+			!useWindowControlsOverlay(this.configurationService) &&	// not when controls are natively drawn
+			this.windowControlsContainer
+		) {
+
+			// Minimize
+			const minimizeIcon = append(this.windowControlsContainer, $('div.window-icon.window-minimize' + ThemeIcon.asCSSSelector(Codicon.chromeMinimize)));
+			this._register(addDisposableListener(minimizeIcon, EventType.CLICK, () => {
+				this.nativeHostService.minimizeWindow({ targetWindowId });
+			}));
+
+			// Restore
+			this.maxRestoreControl = append(this.windowControlsContainer, $('div.window-icon.window-max-restore'));
+			this._register(addDisposableListener(this.maxRestoreControl, EventType.CLICK, async () => {
+				const maximized = await this.nativeHostService.isMaximized({ targetWindowId });
+				if (maximized) {
+					return this.nativeHostService.unmaximizeWindow({ targetWindowId });
+				}
+
+				return this.nativeHostService.maximizeWindow({ targetWindowId });
+			}));
+
+			// Close
+			const closeIcon = append(this.windowControlsContainer, $('div.window-icon.window-close' + ThemeIcon.asCSSSelector(Codicon.chromeClose)));
+			this._register(addDisposableListener(closeIcon, EventType.CLICK, () => {
+				this.nativeHostService.closeWindow({ targetWindowId });
+			}));
+
+			// Resizer
+			this.resizer = append(this.rootContainer, $('div.resizer'));
+			this._register(Event.runAndSubscribe(this.layoutService.onDidChangeWindowMaximized, ({ windowId, maximized }) => {
+				if (windowId === targetWindowId) {
+					this.onDidChangeWindowMaximized(maximized);
+				}
+			}, { windowId: targetWindowId, maximized: this.layoutService.isWindowMaximized(targetWindow) }));
+		}
+
+		// Window System Context Menu
+		// See https://github.com/electron/electron/issues/24893
+		if (isWindows && !hasNativeTitlebar(this.configurationService)) {
+			this._register(this.nativeHostService.onDidTriggerWindowSystemContextMenu(({ windowId, x, y }) => {
+				if (targetWindowId !== windowId) {
+					return;
+				}
+
+				const zoomFactor = getZoomFactor(getWindow(this.element));
+				this.onContextMenu(new MouseEvent(EventType.MOUSE_UP, { clientX: x / zoomFactor, clientY: y / zoomFactor }));
+			}));
+		}
+
+		return result;
+	}
+
+	private onDidChangeWindowMaximized(maximized: boolean): void {
+		if (this.maxRestoreControl) {
+			if (maximized) {
+				this.maxRestoreControl.classList.remove(...ThemeIcon.asClassNameArray(Codicon.chromeMaximize));
+				this.maxRestoreControl.classList.add(...ThemeIcon.asClassNameArray(Codicon.chromeRestore));
+			} else {
+				this.maxRestoreControl.classList.remove(...ThemeIcon.asClassNameArray(Codicon.chromeRestore));
+				this.maxRestoreControl.classList.add(...ThemeIcon.asClassNameArray(Codicon.chromeMaximize));
+			}
+		}
+
+		if (this.resizer) {
+			if (maximized) {
+				hide(this.resizer);
+			} else {
+				show(this.resizer);
+			}
+		}
 	}
 
 	private async handleWindowsAlwaysOnTop(targetWindowId: number, contextKeyService: IContextKeyService): Promise<void> {

From 104aa078054eb6541849af197a737d310b009a8e Mon Sep 17 00:00:00 2001
From: BeniBenj <besimmonds@microsoft.com>
Date: Wed, 13 May 2026 16:04:47 +0200
Subject: [PATCH 10/27] fix window title in agentTtitleBarStatusWidget

---
 src/vs/sessions/browser/parts/titlebarPart.ts       | 13 +++++++++++++
 .../browser/parts/titlebar/titlebarPart.ts          |  6 +++++-
 .../experiments/agentTitleBarStatusWidget.ts        | 13 +++++--------
 .../services/title/browser/titleService.ts          |  8 ++++++++
 4 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/src/vs/sessions/browser/parts/titlebarPart.ts b/src/vs/sessions/browser/parts/titlebarPart.ts
index 3a4735f9961bf..da1a47f999d5d 100644
--- a/src/vs/sessions/browser/parts/titlebarPart.ts
+++ b/src/vs/sessions/browser/parts/titlebarPart.ts
@@ -29,6 +29,7 @@ import { IEditorGroupsContainer } from '../../../workbench/services/editor/commo
 import { CodeWindow, mainWindow } from '../../../base/browser/window.js';
 import { safeIntl } from '../../../base/common/date.js';
 import { ITitlebarPart, ITitleProperties, ITitleVariable, IAuxiliaryTitlebarPart } from '../../../workbench/browser/parts/titlebar/titlebarPart.js';
+import { WindowTitle } from '../../../workbench/browser/parts/titlebar/windowTitle.js';
 import { Menus } from '../menus.js';
 import { IsNewChatSessionContext } from '../../common/contextkeys.js';
 
@@ -473,5 +474,17 @@ export class TitleService extends MultiWindowParts<TitlebarPart> implements ITit
 		}
 	}
 
+	private _windowTitle: WindowTitle | undefined;
+
+	get windowTitle(): WindowTitle {
+		// The Agents window title bar does not render `window.title`, so we
+		// lazily construct a `WindowTitle` only when a consumer (e.g. a custom
+		// command center widget) actually asks for one.
+		if (!this._windowTitle) {
+			this._windowTitle = this._register(this.instantiationService.createInstance(WindowTitle, mainWindow));
+		}
+		return this._windowTitle;
+	}
+
 	//#endregion
 }
diff --git a/src/vs/workbench/browser/parts/titlebar/titlebarPart.ts b/src/vs/workbench/browser/parts/titlebar/titlebarPart.ts
index d03b23148a500..6a984815807c0 100644
--- a/src/vs/workbench/browser/parts/titlebar/titlebarPart.ts
+++ b/src/vs/workbench/browser/parts/titlebar/titlebarPart.ts
@@ -216,6 +216,10 @@ export class BrowserTitleService extends MultiWindowParts<BrowserTitlebarPart> i
 		}
 	}
 
+	get windowTitle(): WindowTitle {
+		return this.mainPart.windowTitle;
+	}
+
 	//#endregion
 }
 
@@ -292,7 +296,7 @@ export class BrowserTitlebarPart extends Part implements ITitlebarPart {
 
 	private readonly isCompactContextKey: IContextKey<boolean>;
 
-	private readonly windowTitle: WindowTitle;
+	readonly windowTitle: WindowTitle;
 
 	protected readonly instantiationService: IInstantiationService;
 
diff --git a/src/vs/workbench/contrib/chat/browser/agentSessions/experiments/agentTitleBarStatusWidget.ts b/src/vs/workbench/contrib/chat/browser/agentSessions/experiments/agentTitleBarStatusWidget.ts
index f4cadd4aa571a..3c5bb258b92d3 100644
--- a/src/vs/workbench/contrib/chat/browser/agentSessions/experiments/agentTitleBarStatusWidget.ts
+++ b/src/vs/workbench/contrib/chat/browser/agentSessions/experiments/agentTitleBarStatusWidget.ts
@@ -43,6 +43,7 @@ import { ChatConfiguration } from '../../../common/constants.js';
 import { IChatEntitlementService } from '../../../../../services/chat/common/chatEntitlementService.js';
 import { IChatWidgetService } from '../../chat.js';
 import { ITelemetryService } from '../../../../../../platform/telemetry/common/telemetry.js';
+import { ITitleService } from '../../../../../services/title/browser/titleService.js';
 
 // Telemetry types
 type AgentStatusClickAction =
@@ -146,11 +147,9 @@ export class AgentTitleBarStatusWidget extends BaseActionViewItem {
 	/** Menu for ChatTitleBarMenu items (same as chat controls dropdown) */
 	private readonly _chatTitleBarMenu;
 
-	/** WindowTitle instance for honoring the user's window.title setting */
-	private readonly _windowTitle: WindowTitle;
-
 	constructor(
 		action: IAction,
+		private readonly _windowTitle: WindowTitle,
 		options: IBaseActionViewItemOptions | undefined,
 		@IInstantiationService private readonly instantiationService: IInstantiationService,
 		@IAgentTitleBarStatusService private readonly agentTitleBarStatusService: IAgentTitleBarStatusService,
@@ -177,9 +176,6 @@ export class AgentTitleBarStatusWidget extends BaseActionViewItem {
 		// Create menu for ChatTitleBarMenu to show in sparkle section dropdown
 		this._chatTitleBarMenu = this._register(this.menuService.createMenu(MenuId.ChatTitleBarMenu, this.contextKeyService));
 
-		// Create WindowTitle to honor the user's window.title setting
-		this._windowTitle = this._register(this.instantiationService.createInstance(WindowTitle, mainWindow));
-
 		// Re-render when control mode or session info changes
 		this._register(this.agentTitleBarStatusService.onDidChangeMode(() => {
 			this._render();
@@ -1400,7 +1396,8 @@ export class AgentTitleBarStatusRendering extends Disposable implements IWorkben
 		@IActionViewItemService actionViewItemService: IActionViewItemService,
 		@IInstantiationService instantiationService: IInstantiationService,
 		@IConfigurationService configurationService: IConfigurationService,
-		@IContextKeyService contextKeyService: IContextKeyService
+		@IContextKeyService contextKeyService: IContextKeyService,
+		@ITitleService titleService: ITitleService,
 	) {
 		super();
 
@@ -1408,7 +1405,7 @@ export class AgentTitleBarStatusRendering extends Disposable implements IWorkben
 			if (!(action instanceof SubmenuItemAction)) {
 				return undefined;
 			}
-			return instantiationService.createInstance(AgentTitleBarStatusWidget, action, options);
+			return instantiationService.createInstance(AgentTitleBarStatusWidget, action, titleService.windowTitle, options);
 		}, undefined));
 
 		// Add/remove CSS classes on workbench based on settings.
diff --git a/src/vs/workbench/services/title/browser/titleService.ts b/src/vs/workbench/services/title/browser/titleService.ts
index 533160479846e..90dbe8c340e89 100644
--- a/src/vs/workbench/services/title/browser/titleService.ts
+++ b/src/vs/workbench/services/title/browser/titleService.ts
@@ -5,6 +5,7 @@
 
 import { createDecorator, IInstantiationService } from '../../../../platform/instantiation/common/instantiation.js';
 import { IAuxiliaryTitlebarPart, ITitlebarPart } from '../../../browser/parts/titlebar/titlebarPart.js';
+import { WindowTitle } from '../../../browser/parts/titlebar/windowTitle.js';
 import { IEditorGroupsContainer } from '../../editor/common/editorGroupsService.js';
 
 export const ITitleService = createDecorator<ITitleService>('titleService');
@@ -13,6 +14,13 @@ export interface ITitleService extends ITitlebarPart {
 
 	readonly _serviceBrand: undefined;
 
+	/**
+	 * The shared {@link WindowTitle} instance for the main window. Used by
+	 * components that need to render or react to the resolved `window.title`
+	 * (template variables, decorations, etc.) without instantiating their own.
+	 */
+	readonly windowTitle: WindowTitle;
+
 	/**
 	 * Get the status bar part that is rooted in the provided container.
 	 */

From fcbd8875899067f9b6a3e7524bd7f43507673abc Mon Sep 17 00:00:00 2001
From: Logan Ramos <lramos15@gmail.com>
Date: Wed, 13 May 2026 10:05:54 -0400
Subject: [PATCH 11/27] Remove old telemetry pipeline (#316236)

---
 extensions/copilot/package.json                     |  1 -
 .../src/extension/extension/vscode-node/services.ts | 10 ++++------
 .../telemetry/common/msftTelemetrySender.ts         | 13 +++----------
 .../platform/telemetry/test/node/telemetry.spec.ts  |  2 +-
 .../vscode-node/microsoftTelemetrySender.ts         |  7 ++-----
 .../telemetry/vscode-node/telemetryServiceImpl.ts   |  2 --
 6 files changed, 10 insertions(+), 25 deletions(-)

diff --git a/extensions/copilot/package.json b/extensions/copilot/package.json
index a12de99ce35eb..cb607b4be012c 100644
--- a/extensions/copilot/package.json
+++ b/extensions/copilot/package.json
@@ -4,7 +4,6 @@
 	"description": "AI chat features powered by Copilot",
 	"version": "0.49.0",
 	"build": "1",
-	"internalAIKey": "1058ec22-3c95-4951-8443-f26c1f325911",
 	"completionsCoreVersion": "1.378.1799",
 	"internalLargeStorageAriaKey": "ec712b3202c5462fb6877acae7f1f9d7-c19ad55e-3e3c-4f99-984b-827f6d95bd9e-6917",
 	"ariaKey": "0c6ae279ed8443289764825290e4f9e2-1a736e7c-1324-4338-be46-fc2a58ae4d14-7255",
diff --git a/extensions/copilot/src/extension/extension/vscode-node/services.ts b/extensions/copilot/src/extension/extension/vscode-node/services.ts
index 38c4a21925b0f..ed3801b5d132e 100644
--- a/extensions/copilot/src/extension/extension/vscode-node/services.ts
+++ b/extensions/copilot/src/extension/extension/vscode-node/services.ts
@@ -182,11 +182,10 @@ export function registerServices(builder: IInstantiationServiceBuilder, extensio
 	builder.define(IImageService, new SyncDescriptor(VSCodeImageServiceImpl));
 
 	builder.define(ITelemetryUserConfig, new SyncDescriptor(TelemetryUserConfigImpl, [undefined, undefined]));
-	const internalAIKey = extensionContext.extension.packageJSON.internalAIKey ?? '';
-	const internalLargeEventAIKey = extensionContext.extension.packageJSON.internalLargeStorageAriaKey ?? '';
+	const internalAIKey = extensionContext.extension.packageJSON.internalLargeStorageAriaKey ?? '';
 	const ariaKey = extensionContext.extension.packageJSON.ariaKey ?? '';
 	if (isTestMode || isScenarioAutomation) {
-		setupTelemetry(builder, extensionContext, internalAIKey, internalLargeEventAIKey, ariaKey);
+		setupTelemetry(builder, extensionContext, internalAIKey, ariaKey);
 		// If we're in testing mode, then most code will be called from an actual test,
 		// and not from here. However, some objects will capture the `accessor` we pass
 		// here and then re-use it later. This is particularly the case for those objects
@@ -194,7 +193,7 @@ export function registerServices(builder: IInstantiationServiceBuilder, extensio
 		// method parameters.
 		builder.define(ICopilotTokenManager, getOrCreateTestingCopilotTokenManager(env.devDeviceId));
 	} else {
-		setupTelemetry(builder, extensionContext, internalAIKey, internalLargeEventAIKey, ariaKey);
+		setupTelemetry(builder, extensionContext, internalAIKey, ariaKey);
 		builder.define(ICopilotTokenManager, new SyncDescriptor(VSCodeCopilotTokenManager));
 	}
 
@@ -325,13 +324,12 @@ function setupMSFTExperimentationService(builder: IInstantiationServiceBuilder,
 	}
 }
 
-function setupTelemetry(builder: IInstantiationServiceBuilder, extensionContext: ExtensionContext, internalAIKey: string, internalLargeEventAIKey: string, externalAIKey: string) {
+function setupTelemetry(builder: IInstantiationServiceBuilder, extensionContext: ExtensionContext, internalAIKey: string, externalAIKey: string) {
 
 	if (ExtensionMode.Production === extensionContext.extensionMode && !isScenarioAutomation) {
 		builder.define(ITelemetryService, new SyncDescriptor(TelemetryService, [
 			extensionContext.extension.packageJSON.name,
 			internalAIKey,
-			internalLargeEventAIKey,
 			externalAIKey,
 			APP_INSIGHTS_KEY_STANDARD,
 			APP_INSIGHTS_KEY_ENHANCED,
diff --git a/extensions/copilot/src/platform/telemetry/common/msftTelemetrySender.ts b/extensions/copilot/src/platform/telemetry/common/msftTelemetrySender.ts
index 0bbc00c2509dc..a50df50a05ce7 100644
--- a/extensions/copilot/src/platform/telemetry/common/msftTelemetrySender.ts
+++ b/extensions/copilot/src/platform/telemetry/common/msftTelemetrySender.ts
@@ -17,7 +17,6 @@ export interface ITelemetryReporter extends ITelemetrySender {
 export class BaseMsftTelemetrySender implements IMSFTTelemetrySender {
 	// Telemetry reporter used for collecting telemetry on internal Microsoft customers
 	protected _internalTelemetryReporter: ITelemetryReporter | undefined;
-	protected _internalLargeEventTelemetryReporter: ITelemetryReporter | undefined;
 	private _externalTelemetryReporter: ITelemetryReporter;
 
 	protected readonly _disposables: DisposableStore = new DisposableStore();
@@ -29,9 +28,9 @@ export class BaseMsftTelemetrySender implements IMSFTTelemetrySender {
 
 	constructor(
 		copilotTokenStore: ICopilotTokenStore,
-		private readonly _createTelemetryReporter: (internal: boolean, largeEvents: boolean) => ITelemetryReporter
+		private readonly _createTelemetryReporter: (internal: boolean) => ITelemetryReporter
 	) {
-		this._externalTelemetryReporter = this._createTelemetryReporter(false, false);
+		this._externalTelemetryReporter = this._createTelemetryReporter(false);
 		this.processToken(copilotTokenStore.copilotToken);
 		this._disposables.add(copilotTokenStore.onDidStoreUpdate(() => this.processToken(copilotTokenStore.copilotToken)));
 	}
@@ -50,9 +49,6 @@ export class BaseMsftTelemetrySender implements IMSFTTelemetrySender {
 		properties = { ...properties, 'common.tid': this._tid, 'common.userName': this._username ?? 'undefined' };
 		measurements = { ...measurements, 'common.isVscodeTeamMember': this._vscodeTeamMember ? 1 : 0 };
 		this._internalTelemetryReporter.sendRawTelemetryEvent(eventName, properties, measurements);
-		if (this._internalLargeEventTelemetryReporter) { // Also duplicate events to the large data store for testing of the pipeline
-			this._internalLargeEventTelemetryReporter.sendRawTelemetryEvent(eventName, properties, measurements);
-		}
 	}
 
 	/**
@@ -106,15 +102,12 @@ export class BaseMsftTelemetrySender implements IMSFTTelemetrySender {
 		this._isInternal = !!token?.isInternal;
 
 		if (this._isInternal) {
-			this._internalTelemetryReporter ??= this._createTelemetryReporter(true, false);
-			this._internalLargeEventTelemetryReporter ??= this._createTelemetryReporter(true, true);
+			this._internalTelemetryReporter ??= this._createTelemetryReporter(true);
 		}
 
 		if (!token || !this._isInternal) {
 			this._internalTelemetryReporter?.dispose();
 			this._internalTelemetryReporter = undefined;
-			this._internalLargeEventTelemetryReporter?.dispose();
-			this._internalLargeEventTelemetryReporter = undefined;
 			return;
 		}
 	}
diff --git a/extensions/copilot/src/platform/telemetry/test/node/telemetry.spec.ts b/extensions/copilot/src/platform/telemetry/test/node/telemetry.spec.ts
index 07e443c86644b..21ee3eee166fc 100644
--- a/extensions/copilot/src/platform/telemetry/test/node/telemetry.spec.ts
+++ b/extensions/copilot/src/platform/telemetry/test/node/telemetry.spec.ts
@@ -97,7 +97,7 @@ suite('Microsoft Telemetry Sender', function () {
 	test('should send internal telemetry event', () => {
 		sender.sendInternalTelemetryEvent('testInternalEvent', { foo: 'bar' }, { 'testMeasure': 1 });
 
-		expect(mockInternalReporter.sendRawTelemetryEvent).toHaveBeenCalledTimes(2);
+		expect(mockInternalReporter.sendRawTelemetryEvent).toHaveBeenCalledOnce();
 		expect(mockInternalReporter.sendRawTelemetryEvent).toHaveBeenCalledWith(
 			'testInternalEvent',
 			{ foo: 'bar', 'common.tid': 'testTid', 'common.userName': 'testUser' },
diff --git a/extensions/copilot/src/platform/telemetry/vscode-node/microsoftTelemetrySender.ts b/extensions/copilot/src/platform/telemetry/vscode-node/microsoftTelemetrySender.ts
index e6d45bd0a969e..1271f990629dd 100644
--- a/extensions/copilot/src/platform/telemetry/vscode-node/microsoftTelemetrySender.ts
+++ b/extensions/copilot/src/platform/telemetry/vscode-node/microsoftTelemetrySender.ts
@@ -10,16 +10,13 @@ import { BaseMsftTelemetrySender } from '../common/msftTelemetrySender';
 export class MicrosoftTelemetrySender extends BaseMsftTelemetrySender {
 	constructor(
 		internalAIKey: string,
-		internalLargeEventAIKey: string,
 		externalAIKey: string,
 		tokenStore: ICopilotTokenStore,
 		customFetcher: CustomFetcher
 	) {
-		const telemetryReporterFactory = (internal: boolean, largeEventReporter: boolean) => {
-			if (internal && !largeEventReporter) {
+		const telemetryReporterFactory = (internal: boolean) => {
+			if (internal) {
 				return new TelemetryReporter(internalAIKey, undefined, undefined, customFetcher);
-			} else if (internal && largeEventReporter) {
-				return new TelemetryReporter(internalLargeEventAIKey, undefined, undefined, customFetcher);
 			} else {
 				return new TelemetryReporter(externalAIKey, undefined, undefined, customFetcher);
 			}
diff --git a/extensions/copilot/src/platform/telemetry/vscode-node/telemetryServiceImpl.ts b/extensions/copilot/src/platform/telemetry/vscode-node/telemetryServiceImpl.ts
index d5fd0384b9bc9..b03c5e1a747d7 100644
--- a/extensions/copilot/src/platform/telemetry/vscode-node/telemetryServiceImpl.ts
+++ b/extensions/copilot/src/platform/telemetry/vscode-node/telemetryServiceImpl.ts
@@ -23,7 +23,6 @@ export class TelemetryService extends BaseTelemetryService {
 	constructor(
 		extensionName: string,
 		internalMSFTAIKey: string,
-		internalLargeEventMSFTAIKey: string,
 		externalMSFTAIKey: string,
 		externalGHAIKey: string,
 		estrictedGHAIKey: string,
@@ -46,7 +45,6 @@ export class TelemetryService extends BaseTelemetryService {
 		};
 		const microsoftTelemetrySender = new MicrosoftTelemetrySender(
 			internalMSFTAIKey,
-			internalLargeEventMSFTAIKey,
 			externalMSFTAIKey,
 			tokenStore,
 			customFetcher

From 1f66fd7bd5c238570d92e86ec4a5754f936abb74 Mon Sep 17 00:00:00 2001
From: Sandeep Somavarapu <sasomava@microsoft.com>
Date: Wed, 13 May 2026 16:07:38 +0200
Subject: [PATCH 12/27] sessions: improve AI readiness of skill and instruction
 files (#316239)

sessions: improve AI readiness of skill and instructions

- Restructure SKILL.md: remove duplicated content, add mandatory
  pre-change reads (coding guidelines, source-code-organization),
  add 'When to read' column to spec table, make valid-layers-check
  mandatory, add common pitfalls section
- Enhance sessions.instructions.md: add architecture overview,
  internal layer diagram, core services table, key development
  patterns (menus, context keys, observables), and learnings section
- Remove window isolation references (not applicable)
- Remove Development Recipes from skill (already in SESSIONS.md)
- Add explicit 'Before Making Any Changes' mandatory reads block
  to ensure coverage in all harnesses (not just VS Code Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .github/instructions/sessions.instructions.md |  76 +++++++
 .github/skills/sessions/SKILL.md              |  77 +++-----
 src/vs/sessions/SESSIONS.md                   |   4 +
 src/vs/sessions/SESSIONS_LIST.md              | 186 ++++++++++++++++++
 4 files changed, 290 insertions(+), 53 deletions(-)
 create mode 100644 src/vs/sessions/SESSIONS_LIST.md

diff --git a/.github/instructions/sessions.instructions.md b/.github/instructions/sessions.instructions.md
index 88189a950f964..cb56021ab8360 100644
--- a/.github/instructions/sessions.instructions.md
+++ b/.github/instructions/sessions.instructions.md
@@ -11,6 +11,76 @@ When working on files under `src/vs/sessions/`, use these skills for detailed gu
 
 - **`sessions`** skill — covers the full architecture: layering, folder structure, chat widget, menus, contributions, entry points, and development guidelines
 
+## Architecture at a Glance
+
+```
+vs/sessions (Agents Window)  ← this layer
+    ↓ imports from
+vs/workbench                 ← standard VS Code
+    ↓
+vs/editor → vs/platform → vs/base
+```
+
+**Layer rule:** `vs/sessions` imports from `vs/workbench` and below. `vs/workbench` must **never** import from `vs/sessions`.
+
+**Internal layers** (see `src/vs/sessions/LAYERS.md`):
+```
+Entry Points → contrib/* / contrib/providers/* / services/* → browser/ & common/ (core)
+```
+
+**Key constraint:** `contrib/*` must NOT import from `contrib/providers/*`. Providers are the most permissive contrib layer and may import from non-provider contribs, services, core, and sibling providers.
+
+## Core Services
+
+| Service | Interface file | Purpose |
+|---------|---------------|---------|
+| `ISessionsManagementService` | `services/sessions/common/sessionsManagement.ts` | Active session tracking, navigation, CRUD operations |
+| `ISessionsProvidersService` | `services/sessions/common/sessionsProvider.ts` | Provider registry (register/unregister/lookup) |
+| `ISession` / `IChat` | `services/sessions/common/session.ts` | Session and chat data interfaces with observable properties |
+
+## Key Development Patterns
+
+### Registering Contributions
+
+All features register through the contribution model and must be imported in entry points:
+- `sessions.common.main.ts` — cross-platform contributions
+- `sessions.desktop.main.ts` — desktop/Electron-specific
+- `sessions.web.main.ts` — web-specific
+
+### Menu Registration
+
+Always use `Menus.*` from `browser/menus.ts` — never `MenuId.*` from `vs/platform/actions`:
+- `Menus.TitleBarLeftLayout` / `Menus.TitleBarRightLayout` — titlebar actions
+- `Menus.SidebarTitle` — sidebar header actions
+- `Menus.AuxiliaryBarTitle` — auxiliary bar header actions
+- `Menus.ChatBarTitle` — chat bar header actions
+
+### Context Keys
+
+All sessions-specific context keys live in `common/contextkeys.ts`:
+- `IsNewChatSessionContext` — whether showing the new session view
+- `ActiveSessionProviderIdContext` — which provider owns the active session
+- `ActiveSessionTypeContext` — session type of the active session
+- `IsPhoneLayoutContext` — whether in phone layout mode
+- `ChatBarVisibleContext` / `ChatBarFocusContext` — chat bar state
+
+### Observable Patterns
+
+```typescript
+// Subscribe to session state changes
+this._register(autorun(reader => {
+    const session = this.sessionsManagementService.activeSession.read(reader);
+    const title = session?.title.read(reader);
+    // React to changes
+}));
+
+// Batch updates
+transaction(tx => {
+    this._title.set(newTitle, tx);
+    this._status.set(newStatus, tx);
+});
+```
+
 ## Mobile Component Architecture
 
 The Agents window has an established mobile architecture (documented in `src/vs/sessions/MOBILE.md`). When adding phone-specific UI — bottom sheets, action sheets, mobile pickers, or any interaction that differs from desktop — follow these rules:
@@ -34,3 +104,9 @@ The Agents window can run on touch-capable platforms (notably iOS). Follow these
 - Do not use `EventType.MOUSE_DOWN`, `EventType.MOUSE_UP`, or `EventType.MOUSE_MOVE` with `addDisposableListener` directly — on iOS, these events don't fire because the platform uses pointer events. Use `addDisposableGenericMouseDownListener`, `addDisposableGenericMouseUpListener`, or `addDisposableGenericMouseMoveListener` instead, which automatically select the correct event type per platform.
 - For custom clickable elements (e.g. picker triggers, title bar pills, or other `<div>`/`<span>` elements styled as buttons) that open pickers or menus on click, listen to **both** `EventType.CLICK` and `TouchEventType.Tap` and call `Gesture.addTarget` on the element. On touch devices, including iOS, VS Code relies on the gesture system to emit `TouchEventType.Tap`, and `EventType.CLICK` alone may not reliably fire there. The base `Button` class already does this correctly, so this rule applies to custom non-`<button>` trigger elements.
 - Add `touch-action: manipulation` in CSS on custom clickable elements (e.g. picker triggers, title bar pills, or other `<div>`/`<span>` elements styled as buttons) to eliminate the 300ms tap delay on touch devices. This is not needed for native `<button>` elements or standard VS Code widgets (quick picks, context menus, action bar items) which already handle touch behavior.
+
+## Learnings
+
+- Always check `src/vs/sessions/LAYERS.md` before adding cross-module imports — layering violations are enforced by ESLint and will fail CI.
+- When creating new views, remember to import the contribution in the entry point — missing this causes the view to not appear.
+- Session state flows through observables, not events. If you find yourself adding `onDid*` events for session state, convert to `IObservable` instead.
diff --git a/.github/skills/sessions/SKILL.md b/.github/skills/sessions/SKILL.md
index ee2f9f270d841..1e3cdc7385a14 100644
--- a/.github/skills/sessions/SKILL.md
+++ b/.github/skills/sessions/SKILL.md
@@ -3,67 +3,38 @@ name: sessions
 description: Agents window architecture — covers the agents-first app, layering, folder structure, chat widget, menus, contributions, entry points, and development guidelines. Use when implementing features or fixing issues in the Agents window.
 ---
 
-When working on the Agents window (`src/vs/sessions/`), always read the relevant specification document before making changes. If you modify the implementation, you **must** update the corresponding spec to keep it in sync.
+## Before Making Any Changes
 
-## Specification Documents
-
-| Document | Path | Covers |
-|----------|------|--------|
-| Overview | `src/vs/sessions/README.md` | Architecture overview, folder conventions |
-| Layer rules | `src/vs/sessions/LAYERS.md` | Import restriction rules for all sessions layers (enforced by ESLint) |
-| Layout spec | `src/vs/sessions/LAYOUT.md` | Grid structure, parts, titlebar, per-session layout state, CSS |
-| Mobile spec | `src/vs/sessions/MOBILE.md` | Mobile component architecture, phone-specific UI patterns |
-| Sessions spec | `src/vs/sessions/SESSIONS.md` | Sessions architecture — layers, provider model, core interfaces, data flow |
-| AI Customizations | `src/vs/sessions/AI_CUSTOMIZATIONS.md` | AI customization editor and tree view design |
-
-## Engineering Principles
-
-### Layering and Dependencies
-
-- **Respect the layer hierarchy.** `vs/sessions` sits above `vs/workbench` — it may import from workbench and below, but workbench must never import from sessions. See `LAYERS.md` for the full internal layer rules.
-- **Keep providers isolated.** Session providers (`contrib/providers/*`) are implementation details of specific backends. Non-provider contributions (`contrib/*`) must not import from providers — extract shared symbols to `services/` or `common/` instead.
-- **Validate layers before committing.** Run `npm run valid-layers-check` to catch violations. Run `npm run compile-check-ts-native` for TypeScript errors — never use raw `tsc`.
-
-### Separation of Concerns
-
-- **Use the contribution model.** Features register through `registerWorkbenchContribution2` and `registerAction2`, imported by entry points (`sessions.common.main.ts`, `sessions.desktop.main.ts`). Don't wire features directly into core workbench code.
-- **Prefer composition over modification.** Extend existing classes (e.g., `AgentSessionsChatWidget` wraps `ChatWidget`) rather than modifying shared workbench components. This keeps the sessions layer decoupled.
-- **Use services for cross-cutting concerns.** Shared state belongs in services (`ISessionsManagementService`, `ISessionsProvidersService`), not passed through component hierarchies. Declare service dependencies in constructors via dependency injection.
+**MANDATORY:** Before writing or modifying any code in `src/vs/sessions/`, you **must** read these documents:
 
-### Reactive State and Observables
+1. **`.github/instructions/coding-guidelines.instructions.md`** — Naming conventions, code style, string localization, disposable management, and DI patterns.
+2. **`.github/instructions/source-code-organization.instructions.md`** — Layers, target environments, dependency injection, and folder structure conventions.
 
-- **Expose mutable state as observables.** Session properties (`title`, `status`, `changes`, etc.) use `IObservable` for reactive UI binding. Use `observableValue`, `derived`, and `autorun` — not events — for state that drives UI updates.
-- **Batch related state changes in transactions.** When updating multiple observables together, wrap in `transaction(tx => { ... })` to avoid intermediate renders.
+Then read the relevant spec for the area you are changing (see table below). If you modify the implementation, you **must** update the corresponding spec to keep it in sync.
 
-### Window Isolation
-
-- **Scope registrations to the Agents window.** Views and contributions that should not appear in regular VS Code use `WindowVisibility.Sessions` in their registration.
-- **Use dedicated menu IDs.** The Agents window defines its own menus in `browser/menus.ts` (`Menus.*`). Never use shared `MenuId.*` constants for Agents window UI.
-- **Use dedicated storage keys.** Prefix with `workbench.agentsession.*` or `workbench.chatbar.*` to avoid conflicts with regular workbench state.
-
-### Layout Stability
-
-- **Maintain fixed positions.** The Agents layout is intentionally non-configurable — no settings-based position customization. New parts go in the right section of the grid.
-- **Preserve no-op stubs.** Unsupported workbench features (zen mode, centered layout, etc.) remain as no-ops — never throw errors for unsupported API calls.
-- **Manage pane composite lifecycle.** When toggling part visibility, always manage the associated pane composites (open default view container on show, dispose on hide).
-
-### Code Organization
-
-- **Core** (layout, parts, shell services) → `browser/`
-- **Feature contributions** (views, actions, editors) → `contrib/<featureName>/browser/`
-- **Session providers** (compute backends) → `contrib/providers/<providerName>/`
-- **Shared service interfaces** → `services/<serviceName>/common/`
+## Specification Documents
 
-## General VS Code Guidelines
+| Document | Path | When to read |
+|----------|------|-------------|
+| Layer rules | `src/vs/sessions/LAYERS.md` | Before adding any cross-module imports. Defines the internal layer hierarchy (`core` → `services` → `contrib` → `providers`) with ESLint-enforced import restrictions. Key rule: `contrib/*` must NOT import from `contrib/providers/*`. |
+| Layout spec | `src/vs/sessions/LAYOUT.md` | Before changing any part, grid structure, titlebar, or CSS. Documents the fixed grid layout (Sidebar \| ChatBar \| AuxiliaryBar), part positions, the modal editor system, per-session layout state persistence, and the titlebar's three-section design. |
+| Sessions spec | `src/vs/sessions/SESSIONS.md` | Before changing session/provider interfaces or data flow. Covers the pluggable provider model (`ISessionsProvider` → `ISessionsProvidersService` → `ISessionsManagementService`), `ISession`/`IChat` interfaces, observable state propagation, workspace/folder model, and session type system. |
+| Sessions list spec | `src/vs/sessions/SESSIONS_LIST.md` | Before changing the sessions sidebar list. Covers the tree widget (`WorkbenchObjectTree`), renderers, grouping (workspace/date), filtering (type/status/archived/read), pinning, read/unread state, workspace capping, mobile adaptations, storage keys, and registered actions. |
+| Mobile spec | `src/vs/sessions/MOBILE.md` | Before adding any phone-specific UI. Covers the mobile part subclass architecture, viewport classification (phone < 640px), `MobileTitlebarPart`, drawer-based sidebar, `MobilePickerSheet`, view/action gating with `IsPhoneLayoutContext`, and the desktop → mobile component mapping. |
+| AI Customizations | `src/vs/sessions/AI_CUSTOMIZATIONS.md` | Before working on the customization editor or tree view. Documents the management editor (in `vs/workbench`) and the tree view/overview (in `vs/sessions/contrib/aiCustomizationTreeView`). |
 
-The Agents window follows all standard VS Code engineering practices. See these instruction files for the full rules:
+## Common Pitfalls
 
-- **Source Code Organization** — `.github/instructions/source-code-organization.instructions.md` (layers, target environments, DI, contribution rules)
-- **Coding Guidelines** — `.github/instructions/coding-guidelines.instructions.md` (naming conventions, code style, string localization, disposable management, DI patterns)
-- **Writing Tests** — `.github/instructions/writing-tests.instructions.md` (unit/integration tests, `ensureNoDisposablesAreLeakedInTestSuite`, snapshot testing, clean teardown)
+- **Wrong menu IDs**: Never use `MenuId.*` from `vs/platform/actions` for Agents window UI. Always use `Menus.*` from `browser/menus.ts`.
+- **Events instead of observables**: Session state must flow through `IObservable`, not `Event`. Use `autorun`/`derived` for reactive UI, not `onDid*` event listeners.
+- **Importing from providers**: Non-provider `contrib/*` code must never import from `contrib/providers/*`. Extract shared interfaces to `services/` or `common/`.
+- **Missing entry point import**: New contribution files must be imported in the appropriate `sessions.*.main.ts` entry point to be loaded (for example `sessions.common.main.ts`, `sessions.desktop.main.ts`, `sessions.web.main.ts`, or `sessions.web.main.internal.ts`).
+- **Modifying workbench code**: Prefer extending/wrapping workbench classes in the sessions layer over modifying shared workbench components.
 
 ## Validating Changes
 
+You **must** run these checks before declaring work complete:
+
 1. `npm run compile-check-ts-native` — TypeScript compilation check. **Do not run `tsc` directly.**
-2. `npm run valid-layers-check` — layering violations (see `LAYERS.md`)
-3. `scripts/test.sh --grep <pattern>` — unit tests (see Writing Tests instructions)
+2. `npm run valid-layers-check` — **MANDATORY.** Catches layering violations. If this fails, fix the imports before proceeding.
+3. `scripts/test.sh --grep <pattern>` — unit tests for affected areas
diff --git a/src/vs/sessions/SESSIONS.md b/src/vs/sessions/SESSIONS.md
index dce70400a3ed4..74f3d1157011d 100644
--- a/src/vs/sessions/SESSIONS.md
+++ b/src/vs/sessions/SESSIONS.md
@@ -67,6 +67,10 @@ Providers can import from all layers below them (core, services, non-provider co
 - [Copilot Chat Sessions Provider](contrib/providers/copilotChatSessions/COPILOT_CHAT_SESSIONS_PROVIDER.md) — wraps `ChatSessionsService`, metadata contract, workspace derivation
 - [Remote Agent Host Provider](contrib/providers/remoteAgentHost/REMOTE_AGENT_HOST_SESSIONS_PROVIDER.md) — remote connections, per-host provider instances
 
+### Related Specifications
+
+- [Sessions List](SESSIONS_LIST.md) — UI surface for browsing sessions: tree widget, grouping, filtering, pinning, read/unread state, mobile adaptations
+
 ---
 
 ## Key Concepts
diff --git a/src/vs/sessions/SESSIONS_LIST.md b/src/vs/sessions/SESSIONS_LIST.md
new file mode 100644
index 0000000000000..fffac6383522c
--- /dev/null
+++ b/src/vs/sessions/SESSIONS_LIST.md
@@ -0,0 +1,186 @@
+# Sessions List
+
+The sessions list is the primary navigation surface in the Agents Window. It occupies the **Sidebar** and presents all sessions from all registered providers as a grouped, filterable, sortable list.
+
+---
+
+## Overview
+
+The sessions list (`SessionsView` + `SessionsList`) displays every session known to `ISessionsManagementService`. Sessions are aggregated from all registered providers and shown in collapsible **sections**. The user can group, sort, filter, pin, and archive sessions. Selecting a session navigates to it.
+
+### Key Files
+
+| File | Purpose |
+|------|---------|
+| `contrib/sessions/browser/views/sessionsView.ts` | `SessionsView` — ViewPane with header, new-session button, sort/group/filter persistence |
+| `contrib/sessions/browser/views/sessionsList.ts` | `SessionsList` — tree control, grouping/filtering logic, menu IDs, context keys |
+| `contrib/sessions/browser/views/sessionsListModelService.ts` | `ISessionsListModelService` — pin/read state (UI-only, not synced to providers) |
+| `contrib/sessions/browser/views/sessionsViewActions.ts` | All registered actions (sort, group, filter, pin, archive, rename, navigate) |
+
+---
+
+## Features
+
+### Session Row
+
+Each session row displays:
+
+- **Status icon** — animated indicator for InProgress / NeedsInput / Error / Completed / Unread
+- **Title** — the session's display title (observable)
+- **Workspace badge** — folder/worktree/cloud icon + label (hidden when redundant with section header)
+- **Diff stats** — `+insertions −deletions` when the session has pending changes
+- **Status description or timestamp** — InProgress/NeedsInput/Error show a status message; otherwise a relative timestamp
+- **Approval row** (optional) — pending agent approvals with an "Allow" button
+
+### Grouping
+
+Sessions are organized into sections with fixed priority:
+
+```
+1. Pinned        ← always first
+2. Regular       ← grouped by workspace or date
+3. Done/Archived ← always last
+```
+
+Two grouping modes (user-switchable):
+
+- **By Workspace** (default) — one section per workspace label, sorted alphabetically. "Unknown" workspace sorts last.
+- **By Date** — sections: Today, Yesterday, Last 7 Days, Older.
+
+Archived sessions always go to the "Done" section regardless of grouping mode. Archive wins over pin — an archived session is never shown in Pinned.
+
+### Sorting
+
+- **By Created** (default) — `createdAt` descending
+- **By Updated** — `updatedAt` descending
+
+### Workspace Group Capping
+
+When grouping by workspace, the list shows only **primary** workspace sections by default:
+
+- A workspace qualifies as primary if it has recent activity (last 4 days), matches the open window's folder, or contains the most recently updated session
+- Remaining workspaces collapse behind a "Show N more" toggle
+- Within each workspace, sessions beyond 5 also show a "Show more" toggle
+- The find widget bypasses all capping
+
+### Filtering
+
+Multiple filter dimensions combine:
+
+| Filter | Default | Effect |
+|--------|---------|--------|
+| Session type | All shown | Hides sessions of specific types (per available session types) |
+| Status | All shown | Hides sessions by `SessionStatus` (InProgress, NeedsInput, Error, Completed, Untitled) |
+| Archived | Hidden | Shows/hides the Done section |
+| Read | All shown | Optionally shows only unread sessions |
+| Agent host | All | Scopes to a specific agent host provider |
+
+The **active session is always visible** even if it would be excluded by filters.
+
+### Find
+
+A built-in find widget filters the list by session title and section label. When active, it bypasses workspace group capping so all matching sessions are visible.
+
+### Pinning
+
+Pinned sessions appear in a dedicated "Pinned" section at the top. Pin state is managed by `ISessionsListModelService` and persisted locally (not synced to providers).
+
+### Read / Unread
+
+- Sessions start as **unread**
+- A session becomes **read** when the user opens it or explicitly marks it
+- A session becomes **unread** when it completes in the background (transitions from InProgress to a terminal status while not active)
+
+### Navigation
+
+- **Clicking a session** marks it read and calls `SessionsManagementService.openSession()`
+- **Active session tracking** — the list auto-scrolls to and selects the active session via an `autorun` on `activeSession`
+- **Keyboard shortcuts** — `Ctrl/Cmd+1..9` opens sessions by index; `Ctrl+Alt+-` / `Ctrl+Alt+Shift+-` for back/forward navigation
+- **Mobile** — opening a session also closes the sidebar drawer
+
+### Mobile
+
+On phone layout (`IsPhoneLayoutContext`):
+
+- Session rows are taller for touch targets; inline toolbars are always visible (no hover)
+- A **filter chips** row appears below the header with status toggles (Completed, In Progress, Failed) and a Sort chip
+- Sort/Group options open as a **bottom sheet** instead of a menu
+
+---
+
+## Menu Entry Points
+
+The sessions list defines menu IDs that contributions can target to add actions. All are exported from `sessionsList.ts` and `sessionsView.ts`.
+
+### Session Item Menus
+
+| Menu | Constant | Where it appears | Use for |
+|------|----------|------------------|---------|
+| `SessionItemToolbar` | `SessionItemToolbarMenuId` | Inline toolbar on each session row (hover on desktop, always on mobile) | Primary actions like pin, archive. Group `navigation` for icons, other groups for overflow. |
+| `SessionItemContextMenu` | `SessionItemContextMenuId` | Right-click context menu on session rows | Secondary actions like rename, mark read/unread. Groups: `0_pin`, `0_read`, `1_edit`. |
+
+### Section Header Menu
+
+| Menu | Constant | Where it appears | Use for |
+|------|----------|------------------|---------|
+| `SessionSectionToolbar` | `SessionSectionToolbarMenuId` | Toolbar on section headers (Pinned, workspace groups, Done) | Section-scoped actions like "New Session for Workspace", "Archive All", "Restore All". |
+
+### View Title Menus
+
+| Menu | Constant | Where it appears | Use for |
+|------|----------|------------------|---------|
+| `SessionsViewPaneFilterSubMenu` | `SessionsViewFilterSubMenu` | Filter/sort dropdown in the view title bar | Sort, group, and workspace capping toggles. |
+| `SessionsViewPaneFilterOptionsSubMenu` | `SessionsViewFilterOptionsSubMenu` | Nested under the filter sub-menu | Session type and status filter checkboxes. |
+
+### Contributing an Action
+
+Register an `Action2` and target one of the menu IDs above. Use the context keys (below) in `when` clauses to scope the action to the right sessions or sections.
+
+```typescript
+registerAction2(class MySessionAction extends Action2 {
+    constructor() {
+        super({
+            id: 'myExtension.mySessionAction',
+            title: localize2('myAction', "My Action"),
+            menu: {
+                id: SessionItemContextMenuId,
+                group: '1_edit',
+                when: ContextKeyExpr.equals('chatSessionType', 'my-session-type'),
+            },
+        });
+    }
+    run(accessor: ServicesAccessor, ...args: unknown[]): void {
+        // action logic
+    }
+});
+```
+
+---
+
+## Context Keys
+
+Context keys available for `when` clauses when contributing to session list menus.
+
+### Per-Session Item
+
+| Key | Type | Description |
+|-----|------|-------------|
+| `sessionItem.isPinned` | boolean | Whether the session is pinned |
+| `sessionItem.isArchived` | boolean | Whether the session is archived |
+| `sessionItem.isRead` | boolean | Whether the session has been read |
+| `sessionItem.hasBranchName` | boolean | Whether the session has a git branch name |
+| `chatSessionType` | string | Session type ID (use to scope actions to specific providers) |
+| `ChatSessionProviderIdContext` | string | Provider ID |
+
+### Per-Section
+
+| Key | Type | Description |
+|-----|------|-------------|
+| `sessionSection.type` | string | `'pinned'`, `'archived'`, `'workspace:<label>'`, `'today'`, etc. |
+
+### View-Level
+
+| Key | Type | Description |
+|-----|------|-------------|
+| `sessionsViewPane.grouping` | string | Current grouping mode (`'workspace'` or `'date'`) |
+| `sessionsViewPane.sorting` | string | Current sorting mode (`'created'` or `'updated'`) |

From 87241c452c50824291013f89db848f7e6ddd686a Mon Sep 17 00:00:00 2001
From: Dmitry Guketlev <yavanosta@gmail.com>
Date: Wed, 13 May 2026 16:21:58 +0200
Subject: [PATCH 13/27] Make appearedInsideViewport in InlineCompletionsModel
 reactive (#289944) (#289946)

Fixed #289944
---
 .../inlineCompletions/browser/model/inlineCompletionsModel.ts   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/vs/editor/contrib/inlineCompletions/browser/model/inlineCompletionsModel.ts b/src/vs/editor/contrib/inlineCompletions/browser/model/inlineCompletionsModel.ts
index 32ef81ec82071..da9869f11f4c9 100644
--- a/src/vs/editor/contrib/inlineCompletions/browser/model/inlineCompletionsModel.ts
+++ b/src/vs/editor/contrib/inlineCompletions/browser/model/inlineCompletionsModel.ts
@@ -78,7 +78,7 @@ export class InlineCompletionsModel extends Disposable {
 			return false;
 		}
 
-		return isSuggestionInViewport(this._editor, state.inlineSuggestion);
+		return isSuggestionInViewport(this._editor, state.inlineSuggestion, reader);
 	});
 	public get isAcceptingPartially() { return this._isAcceptingPartially; }
 

From f30fb0762746b1470b5df8cadde03864b9d43eee Mon Sep 17 00:00:00 2001
From: Alex Ross <38270282+alexr00@users.noreply.github.com>
Date: Wed, 13 May 2026 17:35:51 +0200
Subject: [PATCH 14/27] Wait longer to get settings in
 `_developer.getConfigurationInformation` (#316249)

* Wait longer to get settings in `_developer.getConfigurationInformation`

* CCR feedback
---
 .../preferences/browser/preferencesActions.ts | 34 ++++++++++++++++---
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/src/vs/workbench/contrib/preferences/browser/preferencesActions.ts b/src/vs/workbench/contrib/preferences/browser/preferencesActions.ts
index d9c48dbbaa0c7..2787e7118f02c 100644
--- a/src/vs/workbench/contrib/preferences/browser/preferencesActions.ts
+++ b/src/vs/workbench/contrib/preferences/browser/preferencesActions.ts
@@ -23,8 +23,9 @@ import { IContextKeyService } from '../../../../platform/contextkey/common/conte
 import { IFileService } from '../../../../platform/files/common/files.js';
 import { IExtensionService } from '../../../services/extensions/common/extensions.js';
 import { EnablementState, IWorkbenchExtensionEnablementService, IWorkbenchExtensionManagementService } from '../../../services/extensionManagement/common/extensionManagement.js';
-import { Event } from '../../../../base/common/event.js';
 import { timeout } from '../../../../base/common/async.js';
+import { ExtensionIdentifierSet } from '../../../../platform/extensions/common/extensions.js';
+import { IDisposable } from '../../../../base/common/lifecycle.js';
 
 export class ConfigureLanguageBasedSettingsAction extends Action {
 
@@ -175,9 +176,34 @@ CommandsRegistry.registerCommand({
 		const installed = await extensionManagementService.getInstalled();
 		const toEnable = installed.filter(e => e.isBuiltin && extensionEnablementService.canChangeEnablement(e) && !extensionEnablementService.isEnabled(e));
 		if (toEnable.length) {
-			const registered = Event.toPromise(extensionService.onDidChangeExtensions);
-			await extensionEnablementService.setEnablement(toEnable, EnablementState.EnabledGlobally);
-			await Promise.race([registered, timeout(5000)]);
+			// Wait until every extension we're about to enable has actually been
+			// registered with the extension service (its contributions, including
+			// configuration, are processed at that point). Racing with a single
+			// `onDidChangeExtensions` event is unreliable because the event may
+			// fire before all of the enabled extensions have joined the registry.
+			const pending = new ExtensionIdentifierSet(toEnable.map(e => e.identifier.id));
+			for (const ext of extensionService.extensions) {
+				pending.delete(ext.identifier);
+			}
+			let sub: IDisposable | undefined;
+			const allRegistered = pending.size === 0
+				? Promise.resolve()
+				: new Promise<void>(resolve => {
+					sub = extensionService.onDidChangeExtensions(({ added }) => {
+						for (const ext of added) {
+							pending.delete(ext.identifier);
+						}
+						if (pending.size === 0) {
+							resolve();
+						}
+					});
+				});
+			try {
+				await extensionEnablementService.setEnablement(toEnable, EnablementState.EnabledGlobally);
+				await Promise.race([allRegistered, timeout(15000)]);
+			} finally {
+				sub?.dispose();
+			}
 			await extensionService.whenInstalledExtensionsRegistered();
 		}
 

From 3016c0cd7e2239d82809f2f46af826b2ecae754b Mon Sep 17 00:00:00 2001
From: Paul <paul_wang347@hotmail.com>
Date: Wed, 13 May 2026 08:51:51 -0700
Subject: [PATCH 15/27] Chat input notification fixes (#316105)

---
 .../chatInputNotification.contribution.ts     | 123 ++++++---
 ...chatInputNotification.contribution.spec.ts | 238 +++++++++++++++---
 .../platform/chat/common/chatQuotaService.ts  |   5 +
 .../chat/common/chatQuotaServiceImpl.ts       |  29 ++-
 .../test/common/chatQuotaServiceImpl.spec.ts  |  20 +-
 5 files changed, 329 insertions(+), 86 deletions(-)

diff --git a/extensions/copilot/src/extension/chatInputNotification/vscode-node/chatInputNotification.contribution.ts b/extensions/copilot/src/extension/chatInputNotification/vscode-node/chatInputNotification.contribution.ts
index 9296a81192919..35863ddf05e12 100644
--- a/extensions/copilot/src/extension/chatInputNotification/vscode-node/chatInputNotification.contribution.ts
+++ b/extensions/copilot/src/extension/chatInputNotification/vscode-node/chatInputNotification.contribution.ts
@@ -40,9 +40,14 @@ export class ChatInputNotificationContribution extends Disposable {
 	/** Whether a copilot token was present on the last {@link _update} call. */
 	private _hadCopilotToken = false;
 
-	private readonly _shownQuotaThresholds = new Set<number>();
-	private readonly _shownSessionThresholds = new Set<number>();
-	private readonly _shownWeeklyThresholds = new Set<number>();
+	/**
+	 * Previous percent-used values for threshold crossing detection.
+	 * `undefined` means no data has been seen yet — the first value
+	 * establishes a baseline without triggering a notification.
+	 */
+	private _prevQuotaPercentUsed: number | undefined;
+	private _prevSessionPercentUsed: number | undefined;
+	private _prevWeeklyPercentUsed: number | undefined;
 
 	constructor(
 		@IAuthenticationService private readonly _authService: IAuthenticationService,
@@ -62,11 +67,11 @@ export class ChatInputNotificationContribution extends Disposable {
 		const wasSignedIn = this._hadCopilotToken;
 		this._hadCopilotToken = hasCopilotToken;
 
-		// Detect signed-in → signed-out transition: clear thresholds and hide.
+		// Detect signed-in → signed-out transition: clear state and hide.
 		if (wasSignedIn && !hasCopilotToken) {
-			this._shownQuotaThresholds.clear();
-			this._shownSessionThresholds.clear();
-			this._shownWeeklyThresholds.clear();
+			this._prevQuotaPercentUsed = undefined;
+			this._prevSessionPercentUsed = undefined;
+			this._prevWeeklyPercentUsed = undefined;
 			this._hideNotification();
 			this._showingExhausted = false;
 			return;
@@ -86,7 +91,7 @@ export class ChatInputNotificationContribution extends Disposable {
 		if (isQuotaNotificationEligible) {
 			const quotaWarning = this._computeQuotaWarning();
 			if (quotaWarning) {
-				this._showQuotaApproachingWarning(quotaWarning);
+				this._fetchAndShowQuotaWarning(quotaWarning);
 				return;
 			}
 		}
@@ -105,60 +110,96 @@ export class ChatInputNotificationContribution extends Disposable {
 		}
 	}
 
-	// --- Threshold computation -----------------------------------------------
+	// --- Fetch and show quota warning ----------------------------------------
+
+	/**
+	 * Fetches up-to-date quota data before showing a threshold notification,
+	 * ensuring the displayed percentage reflects the latest server state.
+	 */
+	private async _fetchAndShowQuotaWarning(fallbackWarning: IQuotaWarning): Promise<void> {
+		try {
+			await this._chatQuotaService.refreshQuota();
+			const freshInfo = this._chatQuotaService.quotaInfo;
+			if (freshInfo && !freshInfo.unlimited) {
+				this._showQuotaApproachingWarning({
+					percentUsed: Math.floor(100 - freshInfo.percentRemaining),
+					resetDate: freshInfo.resetDate,
+				});
+			} else {
+				this._showQuotaApproachingWarning(fallbackWarning);
+			}
+		} catch {
+			this._showQuotaApproachingWarning(fallbackWarning);
+		}
+	}
+
+	// --- Threshold crossing detection ----------------------------------------
 
 	private _computeQuotaWarning(): IQuotaWarning | undefined {
 		const info = this._chatQuotaService.quotaInfo;
 		if (!info || info.unlimited) {
+			this._prevQuotaPercentUsed = undefined;
 			return undefined;
 		}
-		return this._checkThreshold(info, this._shownQuotaThresholds);
+		const percentUsed = 100 - info.percentRemaining;
+		const crossed = this._findCrossedThreshold(percentUsed, this._prevQuotaPercentUsed);
+		this._prevQuotaPercentUsed = percentUsed;
+		if (crossed !== undefined) {
+			return { percentUsed: Math.floor(percentUsed), resetDate: info.resetDate };
+		}
+		return undefined;
 	}
 
 	private _computeRateLimitWarning(): IRateLimitWarning | undefined {
 		const { session, weekly } = this._chatQuotaService.rateLimitInfo;
-		const sessionWarning = this._checkThreshold(session, this._shownSessionThresholds);
-		if (sessionWarning) {
-			return { ...sessionWarning, type: 'session' };
+
+		// Always update both prev values so neither becomes stale.
+		const sessionWarning = this._checkCrossing(session, this._prevSessionPercentUsed);
+		this._prevSessionPercentUsed = sessionWarning.newPrev;
+
+		const weeklyWarning = this._checkCrossing(weekly, this._prevWeeklyPercentUsed);
+		this._prevWeeklyPercentUsed = weeklyWarning.newPrev;
+
+		if (sessionWarning.warning) {
+			return { ...sessionWarning.warning, type: 'session' };
 		}
-		const weeklyWarning = this._checkThreshold(weekly, this._shownWeeklyThresholds);
-		if (weeklyWarning) {
-			return { ...weeklyWarning, type: 'weekly' };
+		if (weeklyWarning.warning) {
+			return { ...weeklyWarning.warning, type: 'weekly' };
 		}
 		return undefined;
 	}
 
-	/**
-	 * Checks whether a quota/rate-limit info has crossed a new threshold
-	 * that hasn't been shown yet. Clears stale thresholds when usage drops.
-	 */
-	private _checkThreshold(info: IChatQuota | undefined, shownThresholds: Set<number>): { percentUsed: number; resetDate: Date } | undefined {
-		if (!info) {
-			shownThresholds.clear();
-			return undefined;
-		}
-		if (info.unlimited) {
-			return undefined;
+	private _checkCrossing(
+		info: IChatQuota | undefined,
+		prevPercentUsed: number | undefined,
+	): { newPrev: number | undefined; warning?: { percentUsed: number; resetDate: Date } } {
+		if (!info || info.unlimited) {
+			return { newPrev: undefined };
 		}
-
 		const percentUsed = 100 - info.percentRemaining;
+		const crossed = this._findCrossedThreshold(percentUsed, prevPercentUsed);
+		return {
+			newPrev: percentUsed,
+			warning: crossed !== undefined
+				? { percentUsed: Math.floor(percentUsed), resetDate: info.resetDate }
+				: undefined,
+		};
+	}
 
-		// Clear thresholds that are no longer crossed (usage dropped)
-		for (const threshold of shownThresholds) {
-			if (percentUsed < threshold) {
-				shownThresholds.delete(threshold);
-			}
+	/**
+	 * Returns the highest threshold that was newly crossed, or `undefined`.
+	 * A threshold is "crossed" when the previous value was below it and the
+	 * current value is at or above it.  When `previous` is `undefined` (first
+	 * data arrival), no crossing is detected — only the baseline is stored.
+	 */
+	private _findCrossedThreshold(current: number, previous: number | undefined): number | undefined {
+		if (previous === undefined) {
+			return undefined;
 		}
-
-		// Walk thresholds highest-first so we report the most severe crossed threshold
 		for (let i = THRESHOLDS.length - 1; i >= 0; i--) {
 			const threshold = THRESHOLDS[i];
-			if (percentUsed >= threshold && !shownThresholds.has(threshold)) {
-				// Mark this and all lower thresholds as shown
-				for (let j = 0; j <= i; j++) {
-					shownThresholds.add(THRESHOLDS[j]);
-				}
-				return { percentUsed: Math.floor(percentUsed), resetDate: info.resetDate };
+			if (previous < threshold && current >= threshold) {
+				return threshold;
 			}
 		}
 		return undefined;
diff --git a/extensions/copilot/src/extension/chatInputNotification/vscode-node/test/chatInputNotification.contribution.spec.ts b/extensions/copilot/src/extension/chatInputNotification/vscode-node/test/chatInputNotification.contribution.spec.ts
index d3ccb49c4279c..d2434e099747b 100644
--- a/extensions/copilot/src/extension/chatInputNotification/vscode-node/test/chatInputNotification.contribution.spec.ts
+++ b/extensions/copilot/src/extension/chatInputNotification/vscode-node/test/chatInputNotification.contribution.spec.ts
@@ -80,6 +80,7 @@ function createQuotaService(opts?: {
 		setLastCopilotUsage: vi.fn(),
 		resetTurnCredits: vi.fn(),
 		clearQuota: vi.fn(),
+		refreshQuota: vi.fn().mockResolvedValue(undefined),
 	} as unknown as IChatQuotaService;
 	return { quotaService, emitter };
 }
@@ -116,7 +117,7 @@ describe('ChatInputNotificationContribution', () => {
 		contribution?.dispose();
 	});
 
-	// --- sign-out behaviour (the PR change) ---------------------------------
+	// --- sign-out behaviour --------------------------------------------------
 
 	describe('sign-out clears state and hides notification', () => {
 		test('hides notification when copilot token disappears (sign out)', () => {
@@ -136,31 +137,34 @@ describe('ChatInputNotificationContribution', () => {
 			expect(mockNotification.hide).toHaveBeenCalled();
 		});
 
-		test('re-shows threshold notification after sign-out + sign-in', () => {
-			setup(
-				{},
-				{ quotaInfo: makeQuota(5) }, // 95% used → crosses 95 threshold
-			);
+		test('shows newly crossed threshold after sign-out + sign-in', async () => {
+			setup({}, { quotaInfo: makeQuota(60) }); // 40% used — baseline
 
-			// First update: threshold notification shown
+			// Establish baseline
 			quotaEmitter.fire();
-			expect(mockNotification.show).toHaveBeenCalledTimes(1);
-			mockNotification.show.mockClear();
 
-			// Fire again — same threshold already shown, no new notification
+			// Cross 50% threshold → notification shown
+			(quotaService as any).quotaInfo = makeQuota(50);
 			quotaEmitter.fire();
-			expect(mockNotification.show).not.toHaveBeenCalled();
+			await Promise.resolve();
+			expect(mockNotification.show).toHaveBeenCalledTimes(1);
+			mockNotification.show.mockClear();
 
-			// Sign out → copilot token cleared → thresholds cleared
+			// Sign out → prev values cleared
 			(authService as any).copilotToken = undefined;
 			authEmitter.fire();
 
-			// Sign back in
+			// Sign back in — quota still at 50% → baseline stored, no notification
 			(authService as any).copilotToken = { isFreeUser: false, isNoAuthUser: false, isUsageBasedBilling: true };
-			authEmitter.fire();
+			quotaEmitter.fire();
+			expect(mockNotification.show).not.toHaveBeenCalled();
 
-			// Threshold was cleared, so it should re-show
+			// Usage increases past 75% → new threshold fires
+			(quotaService as any).quotaInfo = makeQuota(25);
+			quotaEmitter.fire();
+			await Promise.resolve();
 			expect(mockNotification.show).toHaveBeenCalled();
+			expect(mockNotification.message).toBe('Credits at 75%');
 		});
 
 		test('sign-out resets showingExhausted flag', () => {
@@ -169,12 +173,10 @@ describe('ChatInputNotificationContribution', () => {
 				{ quotaExhausted: true },
 			);
 
-			// Show exhausted notification
 			quotaEmitter.fire();
 			expect(mockNotification.show).toHaveBeenCalled();
 			mockNotification.show.mockClear();
 
-			// Sign out — copilot token cleared
 			(authService as any).copilotToken = undefined;
 			authEmitter.fire();
 
@@ -185,20 +187,15 @@ describe('ChatInputNotificationContribution', () => {
 			(quotaService as any).rateLimitInfo = { session: undefined, weekly: undefined };
 			authEmitter.fire();
 
-			// Should NOT call hide again (showingExhausted was reset on sign-out)
-			// and should NOT show a new notification (no thresholds crossed)
 			expect(mockNotification.show).not.toHaveBeenCalled();
 		});
 
 		test('sign-out while no notification was active is harmless', () => {
 			setup();
 
-			// No quota events fired yet → no notification created
 			(authService as any).copilotToken = undefined;
 			authEmitter.fire();
 
-			// hide is only called on the notification object; since none was
-			// created, this should not throw.
 			expect(mockNotification.hide).not.toHaveBeenCalled();
 		});
 
@@ -208,8 +205,6 @@ describe('ChatInputNotificationContribution', () => {
 				{ quotaExhausted: true },
 			);
 
-			// Anonymous UBB user has a copilotToken but no GitHub session.
-			// They should still see the exhausted notification.
 			quotaEmitter.fire();
 
 			expect(mockNotification.show).toHaveBeenCalled();
@@ -229,6 +224,154 @@ describe('ChatInputNotificationContribution', () => {
 		});
 	});
 
+	// --- threshold crossing (window reload / sign-in) ------------------------
+
+	describe('threshold crossing on reload and sign-in', () => {
+		test('first data arrival stores baseline without notification', () => {
+			setup(
+				{ anyGitHubSession: { accessToken: 'tok' } },
+				{ quotaInfo: makeQuota(25) }, // 75% used — already above 50% and 75%
+			);
+
+			quotaEmitter.fire();
+
+			expect(mockNotification.show).not.toHaveBeenCalled();
+		});
+
+		test('notifies when crossing a new threshold after baseline', async () => {
+			setup(
+				{ anyGitHubSession: { accessToken: 'tok' } },
+				{ quotaInfo: makeQuota(40) }, // 60% used — baseline
+			);
+
+			quotaEmitter.fire();
+			expect(mockNotification.show).not.toHaveBeenCalled();
+
+			// Usage crosses 75%
+			(quotaService as any).quotaInfo = makeQuota(25);
+			quotaEmitter.fire();
+			await Promise.resolve();
+
+			expect(mockNotification.show).toHaveBeenCalled();
+			expect(mockNotification.message).toBe('Credits at 75%');
+		});
+
+		test('first rate limit data stores baseline without notification', () => {
+			setup(
+				{ anyGitHubSession: { accessToken: 'tok' } },
+				{ session: makeQuota(10) }, // 90% session used
+			);
+
+			quotaEmitter.fire();
+
+			expect(mockNotification.show).not.toHaveBeenCalled();
+		});
+
+		test('notifies when crossing a threshold from below', async () => {
+			setup(
+				{ anyGitHubSession: { accessToken: 'tok' } },
+				{ quotaInfo: makeQuota(60) }, // 40% used — below all thresholds
+			);
+
+			quotaEmitter.fire();
+			expect(mockNotification.show).not.toHaveBeenCalled();
+
+			(quotaService as any).quotaInfo = makeQuota(50); // 50% used
+			quotaEmitter.fire();
+			await Promise.resolve();
+
+			expect(mockNotification.show).toHaveBeenCalled();
+			expect(mockNotification.message).toBe('Credits at 50%');
+		});
+
+		test('sign-out clears baseline so next sign-in re-establishes it', () => {
+			setup(
+				{},
+				{ quotaInfo: makeQuota(25) }, // 75% used
+			);
+
+			// Establish baseline
+			quotaEmitter.fire();
+			expect(mockNotification.show).not.toHaveBeenCalled();
+
+			// Sign out → prev values cleared
+			(authService as any).copilotToken = undefined;
+			authEmitter.fire();
+
+			// Sign back in — first data stores new baseline, no notification
+			(authService as any).copilotToken = { isFreeUser: false, isNoAuthUser: false, isUsageBasedBilling: true };
+			quotaEmitter.fire();
+			expect(mockNotification.show).not.toHaveBeenCalled();
+		});
+
+		test('late sign-in stores baseline then fires on new crossing', async () => {
+			setup({ copilotToken: undefined }, {});
+
+			// Sign in — quota data arrives at 60%
+			(authService as any).copilotToken = { isFreeUser: false, isNoAuthUser: false, isUsageBasedBilling: true };
+			(quotaService as any).quotaInfo = makeQuota(40); // 60% used
+			quotaEmitter.fire();
+			expect(mockNotification.show).not.toHaveBeenCalled();
+
+			// Usage crosses 75% → notification fires
+			(quotaService as any).quotaInfo = makeQuota(25);
+			quotaEmitter.fire();
+			await Promise.resolve();
+
+			expect(mockNotification.show).toHaveBeenCalled();
+			expect(mockNotification.message).toBe('Credits at 75%');
+		});
+
+		test('not signed in → 0% → sign out → 60% does not fire 50% threshold', async () => {
+			setup({ copilotToken: undefined }, {});
+
+			// Sign in at 0%
+			(authService as any).copilotToken = { isFreeUser: false, isNoAuthUser: false, isUsageBasedBilling: true };
+			(quotaService as any).quotaInfo = makeQuota(100); // 0% used
+			quotaEmitter.fire();
+			expect(mockNotification.show).not.toHaveBeenCalled();
+
+			// Sign out → prev cleared
+			(authService as any).copilotToken = undefined;
+			authEmitter.fire();
+
+			// Sign in at 60% — baseline stored, no notification
+			(authService as any).copilotToken = { isFreeUser: false, isNoAuthUser: false, isUsageBasedBilling: true };
+			(quotaService as any).quotaInfo = makeQuota(40); // 60% used
+			quotaEmitter.fire();
+			expect(mockNotification.show).not.toHaveBeenCalled();
+
+			// Usage crosses 75% → notification fires
+			(quotaService as any).quotaInfo = makeQuota(25);
+			quotaEmitter.fire();
+			await Promise.resolve();
+
+			expect(mockNotification.show).toHaveBeenCalled();
+			expect(mockNotification.message).toBe('Credits at 75%');
+		});
+
+		test('sign-out + sign-in at higher level does not fire stale crossing', () => {
+			setup(
+				{},
+				{ quotaInfo: makeQuota(60) }, // 40% used
+			);
+
+			quotaEmitter.fire();
+			expect(mockNotification.show).not.toHaveBeenCalled();
+
+			// Sign out
+			(authService as any).copilotToken = undefined;
+			authEmitter.fire();
+
+			// Sign into different account at 75% — baseline stored, no notification
+			(authService as any).copilotToken = { isFreeUser: false, isNoAuthUser: false, isUsageBasedBilling: true };
+			(quotaService as any).quotaInfo = makeQuota(25); // 75%
+			quotaEmitter.fire();
+
+			expect(mockNotification.show).not.toHaveBeenCalled();
+		});
+	});
+
 	// --- basic notification lifecycle ----------------------------------------
 
 	describe('quota exhausted', () => {
@@ -253,7 +396,6 @@ describe('ChatInputNotificationContribution', () => {
 			quotaEmitter.fire();
 			expect(mockNotification.show).toHaveBeenCalled();
 
-			// Quota replenished
 			(quotaService as any).quotaExhausted = false;
 			quotaEmitter.fire();
 
@@ -262,44 +404,56 @@ describe('ChatInputNotificationContribution', () => {
 	});
 
 	describe('quota approaching threshold', () => {
-		test('shows warning at 50% used', () => {
+		test('shows warning when crossing 50% threshold', async () => {
 			setup(
 				{ anyGitHubSession: { accessToken: 'tok' } },
-				{ quotaInfo: makeQuota(50) }, // 50% used
+				{ quotaInfo: makeQuota(60) }, // 40% used — baseline
 			);
 
 			quotaEmitter.fire();
 
+			(quotaService as any).quotaInfo = makeQuota(50); // 50% used
+			quotaEmitter.fire();
+			await Promise.resolve();
+
 			expect(mockNotification.show).toHaveBeenCalled();
 			expect(mockNotification.message).toBe('Credits at 50%');
 		});
 
-		test('does not re-show the same threshold', () => {
+		test('does not re-show the same threshold', async () => {
 			setup(
 				{ anyGitHubSession: { accessToken: 'tok' } },
-				{ quotaInfo: makeQuota(50) },
+				{ quotaInfo: makeQuota(60) }, // 40% used — baseline
 			);
 
 			quotaEmitter.fire();
+			(quotaService as any).quotaInfo = makeQuota(50);
+			quotaEmitter.fire();
+			await Promise.resolve();
 			expect(mockNotification.show).toHaveBeenCalledTimes(1);
 
 			mockNotification.show.mockClear();
 			quotaEmitter.fire();
+			await Promise.resolve();
 			expect(mockNotification.show).not.toHaveBeenCalled();
 		});
 
-		test('shows higher threshold when usage increases', () => {
+		test('shows higher threshold when usage increases', async () => {
 			setup(
 				{ anyGitHubSession: { accessToken: 'tok' } },
-				{ quotaInfo: makeQuota(50) }, // 50% used
+				{ quotaInfo: makeQuota(60) }, // 40% used — baseline
 			);
 
 			quotaEmitter.fire();
+			(quotaService as any).quotaInfo = makeQuota(50); // 50% used
+			quotaEmitter.fire();
+			await Promise.resolve();
 			expect(mockNotification.show).toHaveBeenCalledTimes(1);
 
 			mockNotification.show.mockClear();
 			(quotaService as any).quotaInfo = makeQuota(10); // 90% used
 			quotaEmitter.fire();
+			await Promise.resolve();
 
 			expect(mockNotification.show).toHaveBeenCalled();
 			expect(mockNotification.message).toBe('Credits at 90%');
@@ -310,9 +464,11 @@ describe('ChatInputNotificationContribution', () => {
 		test('shows session rate limit warning', () => {
 			setup(
 				{ anyGitHubSession: { accessToken: 'tok' } },
-				{ session: makeQuota(25) }, // 75% used
+				{ session: makeQuota(60) }, // 40% session used — baseline
 			);
 
+			quotaEmitter.fire();
+			(quotaService as any).rateLimitInfo = { session: makeQuota(25), weekly: undefined }; // 75% used
 			quotaEmitter.fire();
 
 			expect(mockNotification.show).toHaveBeenCalled();
@@ -323,9 +479,11 @@ describe('ChatInputNotificationContribution', () => {
 		test('shows weekly rate limit warning', () => {
 			setup(
 				{ anyGitHubSession: { accessToken: 'tok' } },
-				{ weekly: makeQuota(10) }, // 90% used
+				{ weekly: makeQuota(60) }, // 40% weekly used — baseline
 			);
 
+			quotaEmitter.fire();
+			(quotaService as any).rateLimitInfo = { session: undefined, weekly: makeQuota(10) }; // 90% used
 			quotaEmitter.fire();
 
 			expect(mockNotification.show).toHaveBeenCalled();
@@ -346,13 +504,17 @@ describe('ChatInputNotificationContribution', () => {
 			expect(mockNotification.message).toBe('Credit Limit Reached');
 		});
 
-		test('threshold warning takes priority over rate limit', () => {
+		test('threshold warning takes priority over rate limit', async () => {
 			setup(
 				{ anyGitHubSession: { accessToken: 'tok' } },
-				{ quotaInfo: makeQuota(10), session: makeQuota(25) }, // 90% quota, 75% session
+				{ quotaInfo: makeQuota(60), session: makeQuota(60) }, // 40% used — baselines
 			);
 
 			quotaEmitter.fire();
+			(quotaService as any).quotaInfo = makeQuota(10); // 90% quota used
+			(quotaService as any).rateLimitInfo = { session: makeQuota(25), weekly: undefined }; // 75% session used
+			quotaEmitter.fire();
+			await Promise.resolve();
 
 			expect(mockNotification.message).toBe('Credits at 90%');
 		});
@@ -367,8 +529,6 @@ describe('ChatInputNotificationContribution', () => {
 
 			quotaEmitter.fire();
 
-			// User was never signed in, so no transition occurred —
-			// notifications should still flow through normally.
 			expect(mockNotification.show).toHaveBeenCalled();
 			expect(mockNotification.message).toBe('Credit Limit Reached');
 		});
@@ -422,9 +582,11 @@ describe('ChatInputNotificationContribution', () => {
 		test('still shows rate limit warning for PRU user', () => {
 			setup(
 				{ copilotToken: { isFreeUser: false, isNoAuthUser: false, isManagedPlan: false, isUsageBasedBilling: false } },
-				{ session: makeQuota(25) }, // 75% used
+				{ session: makeQuota(60) }, // 40% session used — baseline
 			);
 
+			quotaEmitter.fire();
+			(quotaService as any).rateLimitInfo = { session: makeQuota(25), weekly: undefined }; // 75% used
 			quotaEmitter.fire();
 
 			expect(mockNotification.show).toHaveBeenCalled();
diff --git a/extensions/copilot/src/platform/chat/common/chatQuotaService.ts b/extensions/copilot/src/platform/chat/common/chatQuotaService.ts
index db46a55b6a1b2..8e179cf7c3b54 100644
--- a/extensions/copilot/src/platform/chat/common/chatQuotaService.ts
+++ b/extensions/copilot/src/platform/chat/common/chatQuotaService.ts
@@ -84,6 +84,11 @@ export interface IChatQuotaService {
 	/** Reset accumulated credits for the given turn. */
 	resetTurnCredits(turnId: string): void;
 	clearQuota(): void;
+	/**
+	 * Fetches up-to-date quota data from the `copilot_internal/user` endpoint.
+	 * Errors are caught and logged.
+	 */
+	refreshQuota(): Promise<void>;
 }
 
 export const IChatQuotaService = createServiceIdentifier<IChatQuotaService>('IChatQuotaService');
diff --git a/extensions/copilot/src/platform/chat/common/chatQuotaServiceImpl.ts b/extensions/copilot/src/platform/chat/common/chatQuotaServiceImpl.ts
index ed3bbc0eedde8..b765b6ddf3bbe 100644
--- a/extensions/copilot/src/platform/chat/common/chatQuotaServiceImpl.ts
+++ b/extensions/copilot/src/platform/chat/common/chatQuotaServiceImpl.ts
@@ -3,11 +3,13 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
+import { RequestType } from '@vscode/copilot-api';
 import { Emitter } from '../../../util/vs/base/common/event';
 import { Disposable } from '../../../util/vs/base/common/lifecycle';
 import { IAuthenticationService } from '../../authentication/common/authentication';
+import { ICAPIClientService } from '../../endpoint/common/capiClient';
 import { ILogService } from '../../log/common/logService';
-import { IHeaders } from '../../networking/common/fetcherService';
+import { FetchOptions, IHeaders, Response } from '../../networking/common/fetcherService';
 import { CopilotUserQuotaInfo, IChatQuota, IChatQuotaService, QuotaSnapshots } from './chatQuotaService';
 
 export class ChatQuotaService extends Disposable implements IChatQuotaService {
@@ -23,6 +25,7 @@ export class ChatQuotaService extends Disposable implements IChatQuotaService {
 	constructor(
 		@IAuthenticationService private readonly _authService: IAuthenticationService,
 		@ILogService private readonly _logService: ILogService,
+		@ICAPIClientService private readonly _capiClientService: ICAPIClientService,
 	) {
 		super();
 		this._rateLimitInfo = { session: undefined, weekly: undefined };
@@ -118,6 +121,30 @@ export class ChatQuotaService extends Disposable implements IChatQuotaService {
 		}
 	}
 
+	async refreshQuota(): Promise<void> {
+		const githubToken = this._authService.anyGitHubSession?.accessToken;
+		if (!githubToken) {
+			return;
+		}
+		try {
+			const options: FetchOptions = {
+				callSite: 'copilot-quota-refresh',
+				headers: {
+					Authorization: `token ${githubToken}`,
+					'X-GitHub-Api-Version': '2025-04-01',
+				},
+				retryFallbacks: true,
+				expectJSON: true,
+			};
+			const response = await this._capiClientService.makeRequest<Response>(options, { type: RequestType.CopilotUserInfo });
+			const data: CopilotUserQuotaInfo = await response.json();
+			this._processUserInfoQuotaSnapshot(data);
+			this._logService.trace('[ChatQuota] refreshQuota: fetched up-to-date quota data');
+		} catch (error) {
+			this._logService.trace(`[ChatQuota] refreshQuota: failed to fetch quota data: ${error}`);
+		}
+	}
+
 	private _processHeaderValue(header: string): IChatQuota | undefined {
 		try {
 			// Parse URL encoded string into key-value pairs
diff --git a/extensions/copilot/src/platform/chat/test/common/chatQuotaServiceImpl.spec.ts b/extensions/copilot/src/platform/chat/test/common/chatQuotaServiceImpl.spec.ts
index 1adf5bc814cdc..ae11ab0b7784a 100644
--- a/extensions/copilot/src/platform/chat/test/common/chatQuotaServiceImpl.spec.ts
+++ b/extensions/copilot/src/platform/chat/test/common/chatQuotaServiceImpl.spec.ts
@@ -3,12 +3,20 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import { describe, expect, test } from 'vitest';
+import { describe, expect, test, vi } from 'vitest';
 import { Emitter } from '../../../../util/vs/base/common/event';
 import { IAuthenticationService } from '../../../authentication/common/authentication';
+import { ICAPIClientService } from '../../../endpoint/common/capiClient';
 import { TestLogService } from '../../../testing/common/testLogService';
 import { ChatQuotaService } from '../../common/chatQuotaServiceImpl';
 
+function createMockCapiClientService(): ICAPIClientService {
+	return {
+		_serviceBrand: undefined,
+		makeRequest: vi.fn(),
+	} as unknown as ICAPIClientService;
+}
+
 function createMockAuthService(): IAuthenticationService {
 	return {
 		_serviceBrand: undefined,
@@ -46,7 +54,7 @@ type SnapshotData = { quota_id: string; entitlement: number; remaining: number;
 
 describe('ChatQuotaService', () => {
 	function create() {
-		return new ChatQuotaService(createMockAuthService(), new TestLogService());
+		return new ChatQuotaService(createMockAuthService(), new TestLogService(), createMockCapiClientService());
 	}
 
 	const TURN_A = 'turn-a';
@@ -456,7 +464,7 @@ describe('ChatQuotaService', () => {
 	describe('processUserInfoQuotaSnapshot via auth change', () => {
 		test('free user reads from chat snapshot', () => {
 			const { authService, emitter, setToken } = createMockAuthServiceWithEmitter({ isFreeUser: true });
-			const svc = new ChatQuotaService(authService, new TestLogService());
+			const svc = new ChatQuotaService(authService, new TestLogService(), createMockCapiClientService());
 
 			setToken(makeQuotaInfo({
 				chat: { percent_remaining: 30, overage_permitted: false, overage_count: 0, entitlement: 100 },
@@ -474,7 +482,7 @@ describe('ChatQuotaService', () => {
 
 		test('paid user reads from premium_interactions snapshot', () => {
 			const { authService, emitter, setToken } = createMockAuthServiceWithEmitter({ isFreeUser: false });
-			const svc = new ChatQuotaService(authService, new TestLogService());
+			const svc = new ChatQuotaService(authService, new TestLogService(), createMockCapiClientService());
 
 			setToken(makeQuotaInfo({
 				chat: { percent_remaining: 30, overage_permitted: false, overage_count: 0, entitlement: 100 },
@@ -492,7 +500,7 @@ describe('ChatQuotaService', () => {
 
 		test('fires onDidChange when quota is updated', () => {
 			const { authService, emitter, setToken } = createMockAuthServiceWithEmitter({ isFreeUser: true });
-			const svc = new ChatQuotaService(authService, new TestLogService());
+			const svc = new ChatQuotaService(authService, new TestLogService(), createMockCapiClientService());
 			let changeCount = 0;
 			svc.onDidChange(() => changeCount++);
 
@@ -504,7 +512,7 @@ describe('ChatQuotaService', () => {
 
 		test('no-ops when copilotToken has no quotaInfo', () => {
 			const { authService, emitter } = createMockAuthServiceWithEmitter({ isFreeUser: true });
-			const svc = new ChatQuotaService(authService, new TestLogService());
+			const svc = new ChatQuotaService(authService, new TestLogService(), createMockCapiClientService());
 
 			(authService as any).copilotToken = { isFreeUser: true, quotaInfo: undefined };
 			emitter.fire();

From fec57be8249edaf6462931ec7dcf4a570722c0fa Mon Sep 17 00:00:00 2001
From: Martin Aeschlimann <martinae@microsoft.com>
Date: Wed, 13 May 2026 17:54:09 +0200
Subject: [PATCH 16/27] AgentCustomizationItemProvider for both local and
 remote (#315272)

* AgentCustomizationItemProvider for both local and remote

* update

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* update

* only sync plugin & extension customizations

* fix tests

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
---
 .../browser/remoteAgentHost.contribution.ts   |   4 +-
 .../remoteAgentHostCustomizationHarness.ts    | 448 ++----------------
 ...emoteAgentHostCustomizationHarness.test.ts | 100 +++-
 .../agentCustomizationItemProvider.ts         | 416 ++++++++++++++++
 .../agentHost/agentHostChatContribution.ts    |   7 +-
 .../agentHost/agentHostLocalCustomizations.ts |  85 +---
 ...erateLocalCustomizationsForHarness.test.ts |   6 +-
 .../resolveCustomizationRefs.test.ts          |   2 +-
 8 files changed, 553 insertions(+), 515 deletions(-)
 create mode 100644 src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentCustomizationItemProvider.ts

diff --git a/src/vs/sessions/contrib/providers/remoteAgentHost/browser/remoteAgentHost.contribution.ts b/src/vs/sessions/contrib/providers/remoteAgentHost/browser/remoteAgentHost.contribution.ts
index e166a34e46368..0ffe6c966c80f 100644
--- a/src/vs/sessions/contrib/providers/remoteAgentHost/browser/remoteAgentHost.contribution.ts
+++ b/src/vs/sessions/contrib/providers/remoteAgentHost/browser/remoteAgentHost.contribution.ts
@@ -48,7 +48,7 @@ import { IAuthenticationService } from '../../../../../workbench/services/authen
 import { ISessionsProvidersService } from '../../../../services/sessions/browser/sessionsProvidersService.js';
 import { SessionStatus } from '../../../../services/sessions/common/session.js';
 import { remoteAgentHostSessionTypeId } from '../common/remoteAgentHostSessionType.js';
-import { createRemoteAgentHarnessDescriptor, RemoteAgentCustomizationItemProvider, RemoteAgentPluginController } from './remoteAgentHostCustomizationHarness.js';
+import { createRemoteAgentCustomizationItemProvider, createRemoteAgentHarnessDescriptor, RemoteAgentPluginController } from './remoteAgentHostCustomizationHarness.js';
 import { RemoteAgentHostSessionsProvider } from './remoteAgentHostSessionsProvider.js';
 import { SyncedCustomizationBundler } from './syncedCustomizationBundler.js';
 import { ISSHRemoteAgentHostService } from '../../../../../platform/agentHost/common/sshRemoteAgentHost.js';
@@ -628,7 +628,7 @@ export class RemoteAgentHostContribution extends Disposable implements IWorkbenc
 			this._notificationService,
 			this._customizationWorkspaceService,
 		));
-		const itemProvider = agentStore.add(new RemoteAgentCustomizationItemProvider(agent, loggedConnection, sanitized, pluginController, this._fileService, this._logService));
+		const itemProvider = agentStore.add(createRemoteAgentCustomizationItemProvider(agent, loggedConnection, sanitized, pluginController, this._fileService, this._logService));
 		const syncProvider = agentStore.add(new AgentCustomizationSyncProvider(sessionType, this._storageService));
 		const harnessDescriptor = createRemoteAgentHarnessDescriptor(sessionType, displayName, pluginController, itemProvider, syncProvider);
 		agentStore.add(this._customizationHarnessService.registerExternalHarness(harnessDescriptor));
diff --git a/src/vs/sessions/contrib/providers/remoteAgentHost/browser/remoteAgentHostCustomizationHarness.ts b/src/vs/sessions/contrib/providers/remoteAgentHost/browser/remoteAgentHostCustomizationHarness.ts
index c353a3b38d12b..baa4776bd6cb3 100644
--- a/src/vs/sessions/contrib/providers/remoteAgentHost/browser/remoteAgentHostCustomizationHarness.ts
+++ b/src/vs/sessions/contrib/providers/remoteAgentHost/browser/remoteAgentHostCustomizationHarness.ts
@@ -3,15 +3,10 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import { CancellationToken } from '../../../../../base/common/cancellation.js';
+
 import { Codicon } from '../../../../../base/common/codicons.js';
-import { Emitter, Event } from '../../../../../base/common/event.js';
 import { Disposable } from '../../../../../base/common/lifecycle.js';
-import { ResourceMap } from '../../../../../base/common/map.js';
-import { extname } from '../../../../../base/common/path.js';
-import { basename, joinPath } from '../../../../../base/common/resources.js';
-import { SKILL_FILENAME } from '../../../../../workbench/contrib/chat/common/promptSyntax/config/promptFileLocations.js';
-import { PromptFileParser } from '../../../../../workbench/contrib/chat/common/promptSyntax/promptFileParser.js';
+import { basename } from '../../../../../base/common/resources.js';
 import { ThemeIcon } from '../../../../../base/common/themables.js';
 import { URI } from '../../../../../base/common/uri.js';
 import { localize } from '../../../../../nls.js';
@@ -19,95 +14,24 @@ import { AgentHostConfigKey, getAgentHostConfiguredCustomizations } from '../../
 import { agentHostUri } from '../../../../../platform/agentHost/common/agentHostFileSystemProvider.js';
 import { IFileService } from '../../../../../platform/files/common/files.js';
 import { ILogService } from '../../../../../platform/log/common/log.js';
-import { AGENT_HOST_SCHEME, fromAgentHostUri, toAgentHostUri } from '../../../../../platform/agentHost/common/agentHostUri.js';
+import { AGENT_HOST_SCHEME, fromAgentHostUri } from '../../../../../platform/agentHost/common/agentHostUri.js';
 import type { IAgentConnection } from '../../../../../platform/agentHost/common/agentService.js';
 import { ActionType } from '../../../../../platform/agentHost/common/state/sessionActions.js';
-import { type AgentInfo, type CustomizationRef, type RootState, type SessionCustomization, CustomizationStatus } from '../../../../../platform/agentHost/common/state/sessionState.js';
+import { type AgentInfo, type CustomizationRef } from '../../../../../platform/agentHost/common/state/sessionState.js';
 import { IFileDialogService } from '../../../../../platform/dialogs/common/dialogs.js';
 import { INotificationService } from '../../../../../platform/notification/common/notification.js';
 import { AICustomizationManagementSection, IAICustomizationWorkspaceService, type IStorageSourceFilter } from '../../../../../workbench/contrib/chat/common/aiCustomizationWorkspaceService.js';
-import { type IHarnessDescriptor, type ICustomizationItem, type ICustomizationItemAction, type ICustomizationItemProvider } from '../../../../../workbench/contrib/chat/common/customizationHarnessService.js';
+import { type IHarnessDescriptor, type ICustomizationItem, type ICustomizationItemAction } from '../../../../../workbench/contrib/chat/common/customizationHarnessService.js';
 import { PromptsType } from '../../../../../workbench/contrib/chat/common/promptSyntax/promptTypes.js';
 import { PromptsStorage } from '../../../../../workbench/contrib/chat/common/promptSyntax/service/promptsService.js';
 import { BUILTIN_STORAGE } from '../../../chat/common/builtinPromptsStorage.js';
 import { AgentCustomizationSyncProvider } from '../../../../../workbench/contrib/chat/browser/agentSessions/agentHost/agentCustomizationSyncProvider.js';
-import { SYNCED_CUSTOMIZATION_SCHEME } from '../../../../../workbench/services/agentHost/common/agentHostFileSystemService.js';
-
-export { AgentCustomizationSyncProvider as RemoteAgentSyncProvider } from '../../../../../workbench/contrib/chat/browser/agentSessions/agentHost/agentCustomizationSyncProvider.js';
-
-const REMOTE_HOST_GROUP = 'remote-host';
-const REMOTE_CLIENT_GROUP = 'remote-client';
-
-/**
- * Returns `true` for the synthetic "VS Code Synced Data" bundle plugin,
- * which is an implementation detail of the customization sync pipeline
- * and should not be surfaced as a standalone item in the UI.
- */
-function isSyntheticBundle(customization: CustomizationRef): boolean {
-	try {
-		return URI.parse(customization.uri).scheme === SYNCED_CUSTOMIZATION_SCHEME;
-	} catch {
-		return false;
-	}
-}
-
-/**
- * Maps a plugin sub-directory name to the {@link PromptsType}
- * its files represent. Returns `undefined` for unknown directories.
- */
-function promptsTypeForPluginDir(dir: string): PromptsType | undefined {
-	switch (dir) {
-		case 'rules': return PromptsType.instructions;
-		case 'commands': return PromptsType.prompt;
-		case 'agents': return PromptsType.agent;
-		case 'skills': return PromptsType.skill;
-		default: return undefined;
-	}
-}
-
-/**
- * Strips conventional prompt file extensions so we can show `foo`
- * for `foo.prompt.md`, `foo.instructions.md`, etc.
- */
-function stripPromptFileExtensions(filename: string): string {
-	const ext = extname(filename);
-	if (!ext) {
-		return filename;
-	}
-	const stem = filename.slice(0, -ext.length);
-	const dotInStem = stem.lastIndexOf('.');
-	return dotInStem > 0 ? stem.slice(0, dotInStem) : stem;
-}
-
-interface IExpandedPlugin {
-	readonly nonce: string | undefined;
-	readonly children: readonly ICustomizationItem[];
-}
-
-/**
- * Maps a {@link CustomizationStatus} enum value to the string literal
- * expected by {@link ICustomizationItem.status}.
- */
-function toStatusString(status: CustomizationStatus | undefined): 'loading' | 'loaded' | 'degraded' | 'error' | undefined {
-	switch (status) {
-		case CustomizationStatus.Loading: return 'loading';
-		case CustomizationStatus.Loaded: return 'loaded';
-		case CustomizationStatus.Degraded: return 'degraded';
-		case CustomizationStatus.Error: return 'error';
-		default: return undefined;
-	}
-}
+import { AgentCustomizationItemProvider } from '../../../../../workbench/contrib/chat/browser/agentSessions/agentHost/agentCustomizationItemProvider.js';
 
 function customizationKey(customization: CustomizationRef): string {
 	return customization.uri;
 }
 
-function customizationItemKey(customization: CustomizationRef, clientId: string | undefined): string {
-	return clientId !== undefined
-		? `${customizationKey(customization)}::${clientId}`
-		: customizationKey(customization);
-}
-
 /**
  * Owns the client-side UI commands for configuring plugins on a remote
  * agent host. The actual source of truth lives in the host's root config.
@@ -204,8 +128,9 @@ export class RemoteAgentPluginController extends Disposable {
 }
 
 /**
- * Provider that exposes a remote agent's configured plugins as
- * {@link ICustomizationItem} entries for the plugin management widget.
+ * Creates a {@link AgentCustomizationItemProvider} that exposes a
+ * remote agent's configured plugins as {@link ICustomizationItem}
+ * entries for the plugin management widget.
  *
  * Each plugin is also **expanded** into its individual customization
  * files (agents, skills, instructions, prompts) by reading the plugin
@@ -213,336 +138,33 @@ export class RemoteAgentPluginController extends Disposable {
  * children appear in per-type sections (Skills, Agents, etc.) while
  * the parent plugin item appears in the Plugins section.
  */
-export class RemoteAgentCustomizationItemProvider extends Disposable implements ICustomizationItemProvider {
-	private readonly _onDidChange = this._register(new Emitter<void>());
-	readonly onDidChange: Event<void> = this._onDidChange.event;
-
-	private _agentCustomizations: readonly CustomizationRef[];
-	private _sessionCustomizations: readonly SessionCustomization[] | undefined;
-
-	/** Cache: pluginUri → last expansion (keyed by nonce so we re-fetch on content change). */
-	private readonly _expansionCache = new ResourceMap<IExpandedPlugin>();
-
-	constructor(
-		private readonly _agentInfo: AgentInfo,
-		private readonly _connection: IAgentConnection,
-		private readonly _connectionAuthority: string,
-		private readonly _controller: RemoteAgentPluginController,
-		private readonly _fileService: IFileService,
-		private readonly _logService: ILogService,
-	) {
-		super();
-		this._agentCustomizations = this._readRootCustomizations(this._connection.rootState.value) ?? _agentInfo.customizations ?? [];
-
-		this._register(this._connection.rootState.onDidChange(rootState => {
-			const next = this._readRootCustomizations(rootState) ?? this._readAgentCustomizations(rootState) ?? this._agentCustomizations;
-			if (next !== this._agentCustomizations) {
-				this._agentCustomizations = next;
-				this._onDidChange.fire();
-			}
-		}));
-
-		this._register(this._connection.onDidAction(envelope => {
-			if (envelope.action.type === ActionType.SessionCustomizationsChanged) {
-				const customizations = (envelope.action as { customizations?: SessionCustomization[] }).customizations;
-				if (customizations && customizations !== this._sessionCustomizations) {
-					this._sessionCustomizations = customizations;
-					this._onDidChange.fire();
-				}
-			}
-		}));
-	}
-
-	private _readRootCustomizations(rootState: RootState | Error | undefined): readonly CustomizationRef[] | undefined {
-		if (!rootState || rootState instanceof Error || !rootState.config) {
-			return undefined;
-		}
-
-		return getAgentHostConfiguredCustomizations(rootState.config?.values);
-	}
-
-	private _readAgentCustomizations(rootState: RootState | Error | undefined): readonly CustomizationRef[] | undefined {
-		if (!rootState || rootState instanceof Error) {
-			return undefined;
-		}
-
-		return rootState.agents.find(agent => agent.provider === this._agentInfo.provider)?.customizations;
-	}
-
-	private toRemoteUri(customization: CustomizationRef): URI {
-		const original = URI.parse(customization.uri);
-		// The synthetic synced-customization bundle lives in the client's
-		// in-memory filesystem. Don't wrap it as an agent-host:// URI —
-		// the server doesn't have this scheme registered, so wrapping it
-		// would make expansion (and any direct read) fail.
-		if (original.scheme === SYNCED_CUSTOMIZATION_SCHEME) {
-			return original;
-		}
-		return toAgentHostUri(original, this._connectionAuthority);
-	}
-
-	private toBadge(customization: CustomizationRef, fromClient: boolean): { badge?: string; badgeTooltip?: string; groupKey?: string } {
-		if (fromClient) {
-			return {
-				groupKey: REMOTE_CLIENT_GROUP,
-			};
-		}
-
-		return {
-			groupKey: REMOTE_HOST_GROUP,
-		};
-	}
-
-	private getRemovePluginAction(customization: CustomizationRef): ICustomizationItemAction {
-		return {
-			id: 'remoteAgentHost.removeConfiguredPlugin',
-			label: localize('remoteAgentHost.removeConfiguredPlugin', "Remove from Remote Host"),
-			icon: Codicon.trash,
-			run: () => this._controller.removeConfiguredPlugin(customization),
-		};
-	}
-
-	private toItem(customization: CustomizationRef, sessionCustomization?: SessionCustomization): ICustomizationItem {
-		const clientId = sessionCustomization?.clientId; // set if the configuration came from the client
-		const badge = this.toBadge(customization, clientId !== undefined);
-		const uri = this.toRemoteUri(customization);
-		return {
-			itemKey: customizationItemKey(customization, clientId),
-			uri: uri,
-			type: 'plugin',
-			name: customization.displayName,
-			description: customization.description,
-			storage: PromptsStorage.plugin,
-			status: toStatusString(sessionCustomization?.status),
-			statusMessage: sessionCustomization?.statusMessage,
-			enabled: sessionCustomization?.enabled ?? true,
-			badge: badge.badge,
-			badgeTooltip: badge.badgeTooltip,
-			groupKey: badge.groupKey,
-			extensionId: undefined,
-			pluginUri: uri,
-			userInvocable: undefined,
-			actions: clientId === undefined ? [this.getRemovePluginAction(customization)] : undefined,
-		};
-	}
-
-	async provideChatSessionCustomizations(token: CancellationToken): Promise<ICustomizationItem[]> {
-		const items = new Map<string, ICustomizationItem>();
-
-		// Build parent plugin items keyed by customization ref
-		type PluginMeta = { item: ICustomizationItem; nonce: string | undefined; status: ReturnType<typeof toStatusString>; statusMessage: string | undefined; enabled: boolean | undefined; childGroupKey: string; isBundleItem: boolean };
-		const plugins: PluginMeta[] = [];
-
-		for (const customization of this._agentCustomizations) {
-			const item = this.toItem(customization);
-			items.set(customizationItemKey(customization, undefined), item);
-			plugins.push({ item, nonce: customization.nonce, status: undefined, statusMessage: undefined, enabled: undefined, childGroupKey: REMOTE_HOST_GROUP, isBundleItem: false });
-		}
-
-		for (const sessionCustomization of this._sessionCustomizations ?? []) {
-			const isBundleItem = isSyntheticBundle(sessionCustomization.customization);
-			const isClientSynced = sessionCustomization.clientId !== undefined;
-			const childGroupKey = isClientSynced ? REMOTE_CLIENT_GROUP : REMOTE_HOST_GROUP;
-
-			// Always show session customizations as distinct plugin entries —
-			// client-synced items appear in the "Local" group, host-owned in
-			// the "Remote" group. The synthetic bundle is an implementation
-			// detail and is not shown as a standalone entry, but is still
-			// expanded below so individual user files appear in per-type tabs.
-			let item: ICustomizationItem;
-			if (!isBundleItem) {
-				item = this.toItem(sessionCustomization.customization, sessionCustomization);
-				items.set(customizationItemKey(sessionCustomization.customization, sessionCustomization.clientId), item);
-			} else {
-				// create a dummy parent item for the synthetic bundle, it does not go into the items map, just need it to expand.
-				item = { uri: this.toRemoteUri(sessionCustomization.customization), type: 'plugin', name: '', storage: PromptsStorage.plugin, groupKey: childGroupKey, extensionId: undefined, pluginUri: undefined };
-			}
-
-			// Always expand plugin contents so individual files are visible.
-			plugins.push({
-				item,
-				nonce: sessionCustomization.customization.nonce,
-				status: toStatusString(sessionCustomization.status),
-				statusMessage: sessionCustomization.statusMessage,
-				enabled: sessionCustomization.enabled,
-				childGroupKey,
-				isBundleItem,
-			});
-		}
-
-		// Expand each plugin directory in parallel to discover individual
-		// skills, agents, instructions, and prompts inside.
-		const expansions = await Promise.all(plugins.map(p => this._expandPluginContents(p.item.uri, p.nonce, p.childGroupKey, p.isBundleItem, token)));
-		if (token.isCancellationRequested) {
-			return [];
-		}
-
-		for (let i = 0; i < plugins.length; i++) {
-			const p = plugins[i];
-			for (const child of expansions[i]) {
-				// Children inherit the parent plugin's status/enabled state.
-				items.set(`${p.item.itemKey ?? p.item.uri.toString()}::${child.type}::${child.name}`, {
-					...child,
-					status: p.status,
-					statusMessage: p.statusMessage,
-					enabled: p.enabled,
-				});
-			}
-		}
-
-		return [...items.values()];
-	}
-
-	/**
-	 * Reads a plugin's directory contents through the agent-host
-	 * filesystem provider and returns one {@link ICustomizationItem} per
-	 * supported file (agents/skills/instructions/prompts).
-	 *
-	 * Cached by `(uri, nonce)`; a different nonce invalidates the entry.
-	 */
-	private async _expandPluginContents(pluginUri: URI, nonce: string | undefined, groupKey: string, isBundleItem: boolean, token: CancellationToken): Promise<readonly ICustomizationItem[]> {
-		const cached = this._expansionCache.get(pluginUri);
-		if (cached && cached.nonce === nonce) {
-			return cached.children;
-		}
-
-		// pluginUri is already an agent-host:// URI (from toRemoteUri),
-		// so use it directly as the filesystem root.
-		const fsRoot = pluginUri;
-		const children: ICustomizationItem[] = [];
-		try {
-			if (!await this._fileService.canHandleResource(fsRoot)) {
-				return [];
-			}
-			if (token.isCancellationRequested) {
-				return [];
-			}
-
-			const dirNames = ['agents', 'skills', 'commands', 'rules'] as const;
-			const subdirs = dirNames.map(name => ({ name, resource: URI.joinPath(fsRoot, name) }));
-			const stats = await this._fileService.resolveAll(subdirs.map(s => ({ resource: s.resource })));
-
-			if (token.isCancellationRequested) {
-				return [];
-			}
-
-			for (let i = 0; i < subdirs.length; i++) {
-				const stat = stats[i];
-				if (!stat.success || !stat.stat?.isDirectory || !stat.stat.children) {
-					continue;
-				}
-				const promptType = promptsTypeForPluginDir(subdirs[i].name);
-				if (!promptType) {
-					continue;
-				}
-				children.push(...await this._collectFromTypeDir(stat.stat.children, pluginUri, promptType, groupKey, isBundleItem, token));
-			}
-			children.sort((a, b) => `${a.type}:${a.name}`.localeCompare(`${b.type}:${b.name}`));
-		} catch (err) {
-			this._logService.trace(`[RemoteAgentCustomizationItemProvider] Failed to expand plugin ${pluginUri.toString()}: ${err}`);
-			return [];
-		}
-
-		this._expansionCache.set(pluginUri, { nonce, children });
-		return children;
-	}
-
-	/**
-	 * Emits one {@link ICustomizationItem} per child of a per-type
-	 * sub-folder. Skills are conventionally folders containing
-	 * `SKILL.md`, and synced bundles may preserve per-skill
-	 * subdirectories; flat skill files can still appear for legacy
-	 * bundles, so both layouts are accepted.
-	 *
-	 * For skills, the `SKILL.md` frontmatter is read so that the item's
-	 * description (and a frontmatter-supplied name, when present) can be
-	 * surfaced — without it the UI would only show the folder name with
-	 * no description.
-	 */
-	private async _collectFromTypeDir(entries: readonly { name: string; resource: URI; isDirectory: boolean }[], pluginUri: URI, promptType: PromptsType, groupKey: string, isBundleItem: boolean, token: CancellationToken): Promise<ICustomizationItem[]> {
-		type Entry = { name: string; resource: URI; isDirectory: boolean };
-		const eligible: Entry[] = [];
-		for (const child of entries) {
-			// Skip dotfiles (e.g. .DS_Store)
-			if (child.name.startsWith('.')) {
-				continue;
-			}
-			if (promptType !== PromptsType.skill && child.isDirectory) {
-				continue;
-			}
-			eligible.push(child);
-		}
-
-		const skillMetadata = promptType === PromptsType.skill
-			? await Promise.all(eligible.map(child => this._readSkillMetadata(child, token)))
-			: undefined;
-		if (token.isCancellationRequested) {
-			return [];
-		}
-
-		const items: ICustomizationItem[] = [];
-		for (let i = 0; i < eligible.length; i++) {
-			const child = eligible[i];
-			let displayName: string;
-			let description: string | undefined;
-			let uri = child.resource;
-			let userInvocable: boolean | undefined;
-			if (promptType === PromptsType.skill) {
-				const meta = skillMetadata![i];
-				// For folder-style skills the canonical resource for the skill
-				// is its `SKILL.md`; downstream code (slash-command resolution,
-				// chat input decorations) calls `parseNew(item.uri)` and would
-				// otherwise try to read the directory as a file. If we couldn't
-				// read `SKILL.md`, skip the entry rather than emit a URI that
-				// will fail to parse downstream.
-				if (child.isDirectory) {
-					if (!meta) {
-						continue;
-					}
-					uri = joinPath(child.resource, SKILL_FILENAME);
-				}
-				const fallbackName = child.isDirectory ? child.name : stripPromptFileExtensions(child.name);
-				displayName = meta?.name ?? fallbackName;
-				description = meta?.description;
-				userInvocable = meta?.userInvocable;
-			} else {
-				displayName = stripPromptFileExtensions(child.name);
-			}
-			items.push({
-				uri,
-				type: promptType,
-				name: displayName,
-				description,
-				storage: PromptsStorage.plugin,
-				groupKey,
-				extensionId: undefined,
-				pluginUri: isBundleItem ? undefined : pluginUri,
-				userInvocable
-			} satisfies ICustomizationItem);
-		}
-		return items;
-	}
-
-	/**
-	 * Reads `SKILL.md` for a skill entry and returns its frontmatter
-	 * `name` / `description`. Returns `undefined` when the file cannot
-	 * be read or parsed — the caller falls back to the folder name and
-	 * leaves the description empty.
-	 */
-	private async _readSkillMetadata(entry: { name: string; resource: URI; isDirectory: boolean }, token: CancellationToken): Promise<{ name: string | undefined; description: string | undefined; userInvocable: boolean | undefined } | undefined> {
-		const skillFileUri = entry.isDirectory ? joinPath(entry.resource, SKILL_FILENAME) : entry.resource;
-		try {
-			const content = await this._fileService.readFile(skillFileUri);
-			if (token.isCancellationRequested) {
+export function createRemoteAgentCustomizationItemProvider(
+	agentInfo: AgentInfo,
+	connection: IAgentConnection,
+	connectionAuthority: string,
+	controller: RemoteAgentPluginController,
+	fileService: IFileService,
+	logService: ILogService,
+): AgentCustomizationItemProvider {
+	return new AgentCustomizationItemProvider(
+		agentInfo,
+		connection,
+		connectionAuthority,
+		fileService,
+		logService,
+		(customization, clientId) => {
+			if (clientId !== undefined) {
+				// Customization came from the client; we don't allow actions on these since they're read-only reflections of client state.
 				return undefined;
 			}
-			const parsed = new PromptFileParser().parse(skillFileUri, content.value.toString());
-			return { name: parsed.header?.name, description: parsed.header?.description, userInvocable: parsed.header?.userInvocable };
-		} catch (err) {
-			this._logService.trace(`[RemoteAgentCustomizationItemProvider] Failed to read skill metadata ${skillFileUri.toString()}: ${err}`);
-			return undefined;
-		}
-	}
+			return [{
+				id: 'remoteAgentHost.removeConfiguredPlugin',
+				label: localize('remoteAgentHost.removeConfiguredPlugin', "Remove from Remote Host"),
+				icon: Codicon.trash,
+				run: () => controller.removeConfiguredPlugin(customization),
+			}];
+		},
+	);
 }
 
 /**
@@ -553,7 +175,7 @@ export function createRemoteAgentHarnessDescriptor(
 	harnessId: string,
 	displayName: string,
 	controller: RemoteAgentPluginController,
-	itemProvider: RemoteAgentCustomizationItemProvider,
+	itemProvider: AgentCustomizationItemProvider,
 	syncProvider: AgentCustomizationSyncProvider,
 ): IHarnessDescriptor {
 	const allSources = [PromptsStorage.local, PromptsStorage.user, PromptsStorage.plugin, BUILTIN_STORAGE];
diff --git a/src/vs/sessions/contrib/providers/remoteAgentHost/test/browser/remoteAgentHostCustomizationHarness.test.ts b/src/vs/sessions/contrib/providers/remoteAgentHost/test/browser/remoteAgentHostCustomizationHarness.test.ts
index c6c60f55b7c6a..0f626f66c8a84 100644
--- a/src/vs/sessions/contrib/providers/remoteAgentHost/test/browser/remoteAgentHostCustomizationHarness.test.ts
+++ b/src/vs/sessions/contrib/providers/remoteAgentHost/test/browser/remoteAgentHostCustomizationHarness.test.ts
@@ -20,7 +20,12 @@ import { INotificationService } from '../../../../../../platform/notification/co
 import { URI } from '../../../../../../base/common/uri.js';
 import { IAICustomizationWorkspaceService } from '../../../../../../workbench/contrib/chat/common/aiCustomizationWorkspaceService.js';
 import { SYNCED_CUSTOMIZATION_SCHEME } from '../../../../../../workbench/services/agentHost/common/agentHostFileSystemService.js';
-import { RemoteAgentCustomizationItemProvider, RemoteAgentPluginController } from '../../browser/remoteAgentHostCustomizationHarness.js';
+import { createRemoteAgentCustomizationItemProvider, RemoteAgentPluginController } from '../../browser/remoteAgentHostCustomizationHarness.js';
+import { CustomizationHarnessServiceBase, IHarnessDescriptor } from '../../../../../../workbench/contrib/chat/common/customizationHarnessService.js';
+import { PromptsStorage } from '../../../../../../workbench/contrib/chat/common/promptSyntax/service/promptsService.js';
+import { MockPromptsService } from '../../../../../../workbench/contrib/chat/test/common/promptSyntax/service/mockPromptsService.js';
+import { ThemeIcon } from '../../../../../../base/common/themables.js';
+import { Codicon } from '../../../../../../base/common/codicons.js';
 
 class MockAgentConnection extends mock<IAgentConnection>() {
 	declare readonly _serviceBrand: undefined;
@@ -140,7 +145,7 @@ suite('RemoteAgentHostCustomizationHarness', () => {
 			override async resolveAll() { return []; }
 		};
 
-		const provider = disposables.add(new RemoteAgentCustomizationItemProvider(
+		const provider = disposables.add(createRemoteAgentCustomizationItemProvider(
 			createAgentInfo([pluginA, pluginB]),
 			connection,
 			'test-authority',
@@ -180,7 +185,7 @@ suite('RemoteAgentHostCustomizationHarness', () => {
 			override async resolveAll() { return []; }
 		};
 
-		const provider = disposables.add(new RemoteAgentCustomizationItemProvider(
+		const provider = disposables.add(createRemoteAgentCustomizationItemProvider(
 			createAgentInfo([hostScoped]),
 			connection,
 			'test-authority',
@@ -231,7 +236,7 @@ suite('RemoteAgentHostCustomizationHarness', () => {
 			override async resolveAll() { return []; }
 		};
 
-		const provider = disposables.add(new RemoteAgentCustomizationItemProvider(
+		const provider = disposables.add(createRemoteAgentCustomizationItemProvider(
 			createAgentInfo([hostPlugin]),
 			connection,
 			'test-authority',
@@ -329,7 +334,7 @@ suite('RemoteAgentHostCustomizationHarness', () => {
 			}
 		};
 
-		const provider = disposables.add(new RemoteAgentCustomizationItemProvider(
+		const provider = disposables.add(createRemoteAgentCustomizationItemProvider(
 			createAgentInfo([]),
 			connection,
 			'test-authority',
@@ -383,7 +388,7 @@ suite('RemoteAgentHostCustomizationHarness', () => {
 			override async resolveAll() { return []; }
 		};
 
-		const provider = disposables.add(new RemoteAgentCustomizationItemProvider(
+		const provider = disposables.add(createRemoteAgentCustomizationItemProvider(
 			createAgentInfo([]),
 			connection,
 			'test-authority',
@@ -437,7 +442,7 @@ suite('RemoteAgentHostCustomizationHarness', () => {
 			override async resolveAll() { return []; }
 		};
 
-		const provider = disposables.add(new RemoteAgentCustomizationItemProvider(
+		const provider = disposables.add(createRemoteAgentCustomizationItemProvider(
 			createAgentInfo([pluginRef]),
 			connection,
 			'test-authority',
@@ -483,7 +488,7 @@ suite('RemoteAgentHostCustomizationHarness', () => {
 			override async resolveAll() { return []; }
 		};
 
-		const provider = disposables.add(new RemoteAgentCustomizationItemProvider(
+		const provider = disposables.add(createRemoteAgentCustomizationItemProvider(
 			createAgentInfo([pluginRef]),
 			connection,
 			'test-authority',
@@ -532,7 +537,7 @@ suite('RemoteAgentHostCustomizationHarness', () => {
 			override async resolveAll() { return []; }
 		};
 
-		const provider = disposables.add(new RemoteAgentCustomizationItemProvider(
+		const provider = disposables.add(createRemoteAgentCustomizationItemProvider(
 			createAgentInfo([hostPlugin]),
 			connection,
 			'test-authority',
@@ -620,7 +625,7 @@ suite('RemoteAgentHostCustomizationHarness', () => {
 			override async resolveAll() { return []; }
 		};
 
-		const provider = disposables.add(new RemoteAgentCustomizationItemProvider(
+		const provider = disposables.add(createRemoteAgentCustomizationItemProvider(
 			createAgentInfo([]),
 			connection,
 			'test-authority',
@@ -696,7 +701,7 @@ suite('RemoteAgentHostCustomizationHarness', () => {
 			}
 		};
 
-		const provider = disposables.add(new RemoteAgentCustomizationItemProvider(
+		const provider = disposables.add(createRemoteAgentCustomizationItemProvider(
 			createAgentInfo([plugin]),
 			connection,
 			'test-authority',
@@ -715,5 +720,78 @@ suite('RemoteAgentHostCustomizationHarness', () => {
 				{ name: 'legacy', description: undefined, uri: 'vscode-agent-host://test/plugins/skills-bundle/skills/legacy.skill.md' },
 			].sort((a, b) => a.name.localeCompare(b.name)),
 		);
+
+		// Each expanded (non-bundle) item must carry a `pluginUri` so that
+		// downstream slash-command resolution can build a `plugin:`-prefixed
+		// command id via `getCanonicalPluginCommandId`.
+		const expectedPluginUri = 'vscode-agent-host://test-authority/file/-/plugins/skills-bundle';
+		for (const skillItem of skillItems) {
+			assert.strictEqual(skillItem.pluginUri?.toString(), expectedPluginUri, `skill ${skillItem.name} should carry pluginUri`);
+		}
+	});
+
+	test('CustomizationHarnessService.getSlashCommands prefixes discovered skill names with the plugin id', async () => {
+		const connection = disposables.add(new MockAgentConnection());
+		const controller = disposables.add(new RemoteAgentPluginController(
+			'Test Host',
+			'test-authority',
+			connection,
+			{} as IFileDialogService,
+			createNotificationService(),
+			{} as IAICustomizationWorkspaceService,
+		));
+		const plugin: CustomizationRef = { uri: 'file:///plugins/skills-bundle', displayName: 'Skills Bundle' };
+
+		connection.setRootState({ agents: [createAgentInfo([plugin])] });
+
+		const skillsDirChildren: IFileStat[] = [
+			{ name: 'lint', resource: URI.parse('vscode-agent-host://test/plugins/skills-bundle/skills/lint'), isFile: false, isDirectory: true, isSymbolicLink: false, children: undefined },
+		];
+
+		const fileService = new class extends mock<IFileService>() {
+			override async canHandleResource() { return true; }
+			override async resolveAll(toResolve: { resource: URI }[]): Promise<IFileStatResult[]> {
+				return toResolve.map(({ resource }) => {
+					if (resource.path.endsWith('/skills')) {
+						return {
+							success: true,
+							stat: { name: 'skills', resource, isFile: false, isDirectory: true, isSymbolicLink: false, children: skillsDirChildren },
+						};
+					}
+					return { success: false };
+				});
+			}
+			override async readFile(resource: URI): Promise<IFileContent> {
+				if (resource.path.endsWith('/lint/SKILL.md')) {
+					const content = '---\nname: Lint\ndescription: A lint skill\n---\n';
+					return { resource, name: 'SKILL.md', value: VSBuffer.fromString(content), mtime: 0, ctime: 0, etag: '', size: content.length, readonly: false, locked: false, executable: false };
+				}
+				throw new Error('ENOENT');
+			}
+		};
+
+		const provider = disposables.add(createRemoteAgentCustomizationItemProvider(
+			createAgentInfo([plugin]),
+			connection,
+			'test-authority',
+			controller,
+			fileService,
+			new NullLogService(),
+		));
+
+		const harnessId = 'remote-agent-host-test';
+		const descriptor: IHarnessDescriptor = {
+			id: harnessId,
+			label: 'Remote Agent Host (test)',
+			icon: ThemeIcon.fromId(Codicon.remote.id),
+			getStorageSourceFilter: () => ({ sources: [PromptsStorage.plugin] }),
+			itemProvider: provider,
+		};
+		const harnessService = disposables.add(new CustomizationHarnessServiceBase([descriptor], harnessId, new MockPromptsService()));
+
+		const commands = await harnessService.getSlashCommands(harnessId, CancellationToken.None);
+		const skillCommand = commands.find(c => c.type === PromptsType.skill);
+		assert.ok(skillCommand, 'should have a skill slash command');
+		assert.strictEqual(skillCommand.name, 'skills-bundle:lint', 'skill command name should be plugin-prefixed');
 	});
 });
diff --git a/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentCustomizationItemProvider.ts b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentCustomizationItemProvider.ts
new file mode 100644
index 0000000000000..27a88354d62eb
--- /dev/null
+++ b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentCustomizationItemProvider.ts
@@ -0,0 +1,416 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { CancellationToken } from '../../../../../../base/common/cancellation.js';
+import { Disposable } from '../../../../../../base/common/lifecycle.js';
+import { Emitter, Event } from '../../../../../../base/common/event.js';
+import { ResourceMap } from '../../../../../../base/common/map.js';
+import { extname } from '../../../../../../base/common/path.js';
+import { joinPath } from '../../../../../../base/common/resources.js';
+import { URI } from '../../../../../../base/common/uri.js';
+import { CustomizationStatus, type SessionCustomization, type AgentInfo, type CustomizationRef, type RootState } from '../../../../../../platform/agentHost/common/state/sessionState.js';
+import { ILogService } from '../../../../../../platform/log/common/log.js';
+import { ICustomizationItem, ICustomizationItemAction, ICustomizationItemProvider } from '../../../common/customizationHarnessService.js';
+import { PromptsStorage } from '../../../common/promptSyntax/service/promptsService.js';
+import { SYNCED_CUSTOMIZATION_SCHEME } from '../../../../../services/agentHost/common/agentHostFileSystemService.js';
+import { IFileService } from '../../../../../../platform/files/common/files.js';
+import { type IAgentConnection } from '../../../../../../platform/agentHost/common/agentService.js';
+import { ActionType } from '../../../../../../platform/agentHost/common/state/sessionActions.js';
+import { getAgentHostConfiguredCustomizations } from '../../../../../../platform/agentHost/common/agentHostCustomizationConfig.js';
+import { toAgentHostUri } from '../../../../../../platform/agentHost/common/agentHostUri.js';
+import { SKILL_FILENAME } from '../../../common/promptSyntax/config/promptFileLocations.js';
+import { PromptFileParser } from '../../../common/promptSyntax/promptFileParser.js';
+import { PromptsType } from '../../../common/promptSyntax/promptTypes.js';
+
+
+const REMOTE_HOST_GROUP = 'remote-host';
+const REMOTE_CLIENT_GROUP = 'remote-client';
+
+
+export class AgentCustomizationItemProvider extends Disposable implements ICustomizationItemProvider {
+	private readonly _onDidChange = this._register(new Emitter<void>());
+	readonly onDidChange: Event<void> = this._onDidChange.event;
+
+	private _agentCustomizations: readonly CustomizationRef[];
+	private _sessionCustomizations: readonly SessionCustomization[] | undefined;
+
+	/** Cache: pluginUri → last expansion (keyed by nonce so we re-fetch on content change). */
+	private readonly _expansionCache = new ResourceMap<{ nonce: string | undefined; children: readonly ICustomizationItem[] }>();
+
+	constructor(
+		private readonly _agentInfo: AgentInfo,
+		connection: IAgentConnection,
+		private readonly _connectionAuthority: string,
+		private readonly _fileService: IFileService,
+		private readonly _logService: ILogService,
+		private readonly _getItemActions?: (customization: CustomizationRef, clientId: string | undefined) => ICustomizationItemAction[] | undefined,
+	) {
+		super();
+		const rootStateSubscription = connection.rootState;
+		this._agentCustomizations = this._readRootCustomizations(rootStateSubscription.value) ?? this._agentInfo.customizations ?? [];
+
+		this._register(rootStateSubscription.onDidChange(rootState => {
+			const next = this._readRootCustomizations(rootState) ?? this._readAgentCustomizations(rootState) ?? this._agentCustomizations;
+			if (next !== this._agentCustomizations) {
+				this._agentCustomizations = next;
+				this._onDidChange.fire();
+			}
+		}));
+
+		this._register(connection.onDidAction(envelope => {
+			if (envelope.action.type === ActionType.SessionCustomizationsChanged) {
+				const customizations = envelope.action.customizations;
+				if (customizations !== this._sessionCustomizations) {
+					this._sessionCustomizations = customizations;
+					this._onDidChange.fire();
+				}
+			}
+		}));
+	}
+
+
+	private _readRootCustomizations(rootState: RootState | Error | undefined): readonly CustomizationRef[] | undefined {
+		if (!rootState || rootState instanceof Error || !rootState.config) {
+			return undefined;
+		}
+
+		return getAgentHostConfiguredCustomizations(rootState.config?.values);
+	}
+
+	private _readAgentCustomizations(rootState: RootState | Error | undefined): readonly CustomizationRef[] | undefined {
+		if (!rootState || rootState instanceof Error) {
+			return undefined;
+		}
+
+		return rootState.agents.find(agent => agent.provider === this._agentInfo.provider)?.customizations;
+	}
+
+	private toRemoteUri(customization: CustomizationRef): URI {
+		const original = URI.parse(customization.uri);
+		// The synthetic synced-customization bundle lives in the client's
+		// in-memory filesystem. Don't wrap it as an agent-host:// URI —
+		// the server doesn't have this scheme registered, so wrapping it
+		// would make expansion (and any direct read) fail.
+		if (original.scheme === SYNCED_CUSTOMIZATION_SCHEME) {
+			return original;
+		}
+		return toAgentHostUri(original, this._connectionAuthority);
+	}
+
+	private toBadge(customization: CustomizationRef, fromClient: boolean): { badge?: string; badgeTooltip?: string; groupKey?: string } {
+		if (fromClient) {
+			return {
+				groupKey: REMOTE_CLIENT_GROUP,
+			};
+		}
+
+		return {
+			groupKey: REMOTE_HOST_GROUP,
+		};
+	}
+
+	private toItem(customization: CustomizationRef, sessionCustomization?: SessionCustomization): ICustomizationItem {
+		const clientId = sessionCustomization?.clientId; // set if the configuration came from the client
+		const badge = this.toBadge(customization, clientId !== undefined);
+		const uri = this.toRemoteUri(customization);
+		return {
+			itemKey: customizationItemKey(customization, clientId),
+			uri: uri,
+			type: 'plugin',
+			name: customization.displayName,
+			description: customization.description,
+			storage: PromptsStorage.plugin,
+			status: toStatusString(sessionCustomization?.status),
+			statusMessage: sessionCustomization?.statusMessage,
+			enabled: sessionCustomization?.enabled ?? true,
+			badge: badge.badge,
+			badgeTooltip: badge.badgeTooltip,
+			groupKey: badge.groupKey,
+			extensionId: undefined,
+			pluginUri: uri,
+			userInvocable: undefined,
+			actions: this._getItemActions?.(customization, clientId),
+		};
+	}
+
+	async provideChatSessionCustomizations(token: CancellationToken): Promise<ICustomizationItem[]> {
+		const items = new Map<string, ICustomizationItem>();
+
+		// Build parent plugin items keyed by customization ref
+		type PluginMeta = { item: ICustomizationItem; nonce: string | undefined; status: ReturnType<typeof toStatusString>; statusMessage: string | undefined; enabled: boolean | undefined; childGroupKey: string; isBundleItem: boolean };
+		const plugins: PluginMeta[] = [];
+
+		for (const customization of this._agentCustomizations) {
+			const item = this.toItem(customization);
+			items.set(customizationItemKey(customization, undefined), item);
+			plugins.push({ item, nonce: customization.nonce, status: undefined, statusMessage: undefined, enabled: undefined, childGroupKey: REMOTE_HOST_GROUP, isBundleItem: false });
+		}
+
+		for (const sessionCustomization of this._sessionCustomizations ?? []) {
+			const isBundleItem = isSyntheticBundle(sessionCustomization.customization);
+			const isClientSynced = sessionCustomization.clientId !== undefined;
+			const childGroupKey = isClientSynced ? REMOTE_CLIENT_GROUP : REMOTE_HOST_GROUP;
+
+			// Always show session customizations as distinct plugin entries —
+			// client-synced items appear in the "Local" group, host-owned in
+			// the "Remote" group. The synthetic bundle is an implementation
+			// detail and is not shown as a standalone entry, but is still
+			// expanded below so individual user files appear in per-type tabs.
+			let item: ICustomizationItem;
+			if (!isBundleItem) {
+				item = this.toItem(sessionCustomization.customization, sessionCustomization);
+				items.set(customizationItemKey(sessionCustomization.customization, sessionCustomization.clientId), item);
+			} else {
+				// create a dummy parent item for the synthetic bundle, it does not go into the items map, just need it to expand.
+				item = { uri: this.toRemoteUri(sessionCustomization.customization), type: 'plugin', name: '', storage: PromptsStorage.plugin, groupKey: childGroupKey, extensionId: undefined, pluginUri: undefined };
+			}
+
+			// Always expand plugin contents so individual files are visible.
+			plugins.push({
+				item,
+				nonce: sessionCustomization.customization.nonce,
+				status: toStatusString(sessionCustomization.status),
+				statusMessage: sessionCustomization.statusMessage,
+				enabled: sessionCustomization.enabled,
+				childGroupKey,
+				isBundleItem,
+			});
+		}
+
+		// Expand each plugin directory in parallel to discover individual
+		// skills, agents, instructions, and prompts inside.
+		const expansions = await Promise.all(plugins.map(p => this._expandPluginContents(p.item.uri, p.nonce, p.childGroupKey, p.isBundleItem, token)));
+		if (token.isCancellationRequested) {
+			return [];
+		}
+
+		for (let i = 0; i < plugins.length; i++) {
+			const p = plugins[i];
+			for (const child of expansions[i]) {
+				// Children inherit the parent plugin's status/enabled state.
+				items.set(`${p.item.itemKey ?? p.item.uri.toString()}::${child.type}::${child.name}`, {
+					...child,
+					status: p.status,
+					statusMessage: p.statusMessage,
+					enabled: p.enabled,
+				});
+			}
+		}
+
+		return [...items.values()];
+	}
+
+	/**
+	 * Reads a plugin's directory contents through the agent-host
+	 * filesystem provider and returns one {@link ICustomizationItem} per
+	 * supported file (agents/skills/instructions/prompts).
+	 *
+	 * Cached by `(uri, nonce)`; a different nonce invalidates the entry.
+	 */
+	private async _expandPluginContents(pluginUri: URI, nonce: string | undefined, groupKey: string, isBundleItem: boolean, token: CancellationToken): Promise<readonly ICustomizationItem[]> {
+		const cached = this._expansionCache.get(pluginUri);
+		if (cached && cached.nonce === nonce) {
+			return cached.children;
+		}
+
+		// pluginUri is already an agent-host:// URI (from toRemoteUri),
+		// so use it directly as the filesystem root.
+		const fsRoot = pluginUri;
+		const children: ICustomizationItem[] = [];
+		try {
+			if (!await this._fileService.canHandleResource(fsRoot)) {
+				return [];
+			}
+			if (token.isCancellationRequested) {
+				return [];
+			}
+
+			const dirNames = ['agents', 'skills', 'commands', 'rules'] as const;
+			const subdirs = dirNames.map(name => ({ name, resource: URI.joinPath(fsRoot, name) }));
+			const stats = await this._fileService.resolveAll(subdirs.map(s => ({ resource: s.resource })));
+
+			if (token.isCancellationRequested) {
+				return [];
+			}
+
+			for (let i = 0; i < subdirs.length; i++) {
+				const stat = stats[i];
+				if (!stat.success || !stat.stat?.isDirectory || !stat.stat.children) {
+					continue;
+				}
+				const promptType = promptsTypeForPluginDir(subdirs[i].name);
+				if (!promptType) {
+					continue;
+				}
+				children.push(...await this._collectFromTypeDir(stat.stat.children, pluginUri, promptType, groupKey, isBundleItem, token));
+			}
+			children.sort((a, b) => `${a.type}:${a.name}`.localeCompare(`${b.type}:${b.name}`));
+		} catch (err) {
+			this._logService.trace(`[AgentCustomizationItemProvider] Failed to expand plugin ${pluginUri.toString()}: ${err}`);
+			return [];
+		}
+
+		this._expansionCache.set(pluginUri, { nonce, children });
+		return children;
+	}
+
+	/**
+	 * Emits one {@link ICustomizationItem} per child of a per-type
+	 * sub-folder. Skills are conventionally folders containing
+	 * `SKILL.md`, and synced bundles may preserve per-skill
+	 * subdirectories; flat skill files can still appear for legacy
+	 * bundles, so both layouts are accepted.
+	 *
+	 * For skills, the `SKILL.md` frontmatter is read so that the item's
+	 * description (and a frontmatter-supplied name, when present) can be
+	 * surfaced — without it the UI would only show the folder name with
+	 * no description.
+	 */
+	private async _collectFromTypeDir(entries: readonly { name: string; resource: URI; isDirectory: boolean }[], pluginUri: URI, promptType: PromptsType, groupKey: string, isBundleItem: boolean, token: CancellationToken): Promise<ICustomizationItem[]> {
+		type Entry = { name: string; resource: URI; isDirectory: boolean };
+		const eligible: Entry[] = [];
+		for (const child of entries) {
+			// Skip dotfiles (e.g. .DS_Store)
+			if (child.name.startsWith('.')) {
+				continue;
+			}
+			if (promptType !== PromptsType.skill && child.isDirectory) {
+				continue;
+			}
+			eligible.push(child);
+		}
+
+		const skillMetadata = promptType === PromptsType.skill
+			? await Promise.all(eligible.map(child => this._readSkillMetadata(child, token)))
+			: undefined;
+		if (token.isCancellationRequested) {
+			return [];
+		}
+
+		const items: ICustomizationItem[] = [];
+		for (let i = 0; i < eligible.length; i++) {
+			const child = eligible[i];
+			let displayName: string;
+			let description: string | undefined;
+			let uri = child.resource;
+			let userInvocable: boolean | undefined;
+			if (promptType === PromptsType.skill) {
+				const meta = skillMetadata![i];
+				// For folder-style skills the canonical resource for the skill
+				// is its `SKILL.md`; downstream code (slash-command resolution,
+				// chat input decorations) calls `parseNew(item.uri)` and would
+				// otherwise try to read the directory as a file. If we couldn't
+				// read `SKILL.md`, skip the entry rather than emit a URI that
+				// will fail to parse downstream.
+				if (child.isDirectory) {
+					if (!meta) {
+						continue;
+					}
+					uri = joinPath(child.resource, SKILL_FILENAME);
+				}
+				const fallbackName = child.isDirectory ? child.name : stripPromptFileExtensions(child.name);
+				displayName = meta?.name ?? fallbackName;
+				description = meta?.description;
+				userInvocable = meta?.userInvocable;
+			} else {
+				displayName = stripPromptFileExtensions(child.name);
+			}
+			items.push({
+				uri,
+				type: promptType,
+				name: displayName,
+				description,
+				storage: PromptsStorage.plugin,
+				groupKey,
+				extensionId: undefined,
+				pluginUri: isBundleItem ? undefined : pluginUri,
+				userInvocable
+			} satisfies ICustomizationItem);
+		}
+		return items;
+	}
+
+	/**
+	 * Reads `SKILL.md` for a skill entry and returns its frontmatter
+	 * `name` / `description`. Returns `undefined` when the file cannot
+	 * be read or parsed — the caller falls back to the folder name and
+	 * leaves the description empty.
+	 */
+	private async _readSkillMetadata(entry: { name: string; resource: URI; isDirectory: boolean }, token: CancellationToken): Promise<{ name: string | undefined; description: string | undefined; userInvocable: boolean | undefined } | undefined> {
+		const skillFileUri = entry.isDirectory ? joinPath(entry.resource, SKILL_FILENAME) : entry.resource;
+		try {
+			const content = await this._fileService.readFile(skillFileUri);
+			if (token.isCancellationRequested) {
+				return undefined;
+			}
+			const parsed = new PromptFileParser().parse(skillFileUri, content.value.toString());
+			return { name: parsed.header?.name, description: parsed.header?.description, userInvocable: parsed.header?.userInvocable };
+		} catch (err) {
+			this._logService.trace(`[RemoteAgentCustomizationItemProvider] Failed to read skill metadata ${skillFileUri.toString()}: ${err}`);
+			return undefined;
+		}
+	}
+}
+
+function toStatusString(status: CustomizationStatus | undefined): 'loading' | 'loaded' | 'degraded' | 'error' | undefined {
+	switch (status) {
+		case CustomizationStatus.Loading: return 'loading';
+		case CustomizationStatus.Loaded: return 'loaded';
+		case CustomizationStatus.Degraded: return 'degraded';
+		case CustomizationStatus.Error: return 'error';
+		default: return undefined;
+	}
+}
+
+function customizationKey(customization: CustomizationRef): string {
+	return customization.uri;
+}
+
+function customizationItemKey(customization: CustomizationRef, clientId: string | undefined): string {
+	return clientId !== undefined
+		? `${customizationKey(customization)}::${clientId}`
+		: customizationKey(customization);
+}
+
+/**
+ * Returns `true` for the synthetic "VS Code Synced Data" bundle plugin,
+ * which is an implementation detail of the customization sync pipeline
+ * and should not be surfaced as a standalone item in the UI.
+ */
+function isSyntheticBundle(customization: CustomizationRef): boolean {
+	try {
+		return URI.parse(customization.uri).scheme === SYNCED_CUSTOMIZATION_SCHEME;
+	} catch {
+		return false;
+	}
+}
+
+/**
+ * Maps a plugin sub-directory name to the {@link PromptsType}
+ * its files represent. Returns `undefined` for unknown directories.
+ */
+function promptsTypeForPluginDir(dir: string): PromptsType | undefined {
+	switch (dir) {
+		case 'rules': return PromptsType.instructions;
+		case 'commands': return PromptsType.prompt;
+		case 'agents': return PromptsType.agent;
+		case 'skills': return PromptsType.skill;
+		default: return undefined;
+	}
+}
+
+/**
+ * Strips conventional prompt file extensions so we can show `foo`
+ * for `foo.prompt.md`, `foo.instructions.md`, etc.
+ */
+function stripPromptFileExtensions(filename: string): string {
+	const ext = extname(filename);
+	if (!ext) {
+		return filename;
+	}
+	const stem = filename.slice(0, -ext.length);
+	const dotInStem = stem.lastIndexOf('.');
+	return dotInStem > 0 ? stem.slice(0, dotInStem) : stem;
+}
diff --git a/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostChatContribution.ts b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostChatContribution.ts
index 009d27099fe89..16ec66b3ac622 100644
--- a/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostChatContribution.ts
+++ b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostChatContribution.ts
@@ -14,6 +14,7 @@ import { type ProtectedResourceMetadata } from '../../../../../../platform/agent
 import { type AgentInfo, type CustomizationRef, type RootState } from '../../../../../../platform/agentHost/common/state/sessionState.js';
 import { IConfigurationService } from '../../../../../../platform/configuration/common/configuration.js';
 import { IDefaultAccountService } from '../../../../../../platform/defaultAccount/common/defaultAccount.js';
+import { IFileService } from '../../../../../../platform/files/common/files.js';
 import { IInstantiationService } from '../../../../../../platform/instantiation/common/instantiation.js';
 import { ILogService } from '../../../../../../platform/log/common/log.js';
 import { IStorageService } from '../../../../../../platform/storage/common/storage.js';
@@ -26,8 +27,9 @@ import { ICustomizationHarnessService } from '../../../common/customizationHarne
 import { ILanguageModelsService } from '../../../common/languageModels.js';
 import { IAgentPluginService } from '../../../common/plugins/agentPluginService.js';
 import { IPromptsService, PromptsStorage } from '../../../common/promptSyntax/service/promptsService.js';
+import { AgentCustomizationItemProvider } from './agentCustomizationItemProvider.js';
 import { AgentCustomizationSyncProvider } from './agentCustomizationSyncProvider.js';
-import { LocalAgentHostCustomizationItemProvider, resolveCustomizationRefs } from './agentHostLocalCustomizations.js';
+import { resolveCustomizationRefs } from './agentHostLocalCustomizations.js';
 import { authenticateProtectedResources, AgentHostAuthTokenCache, resolveAuthenticationInteractively } from './agentHostAuth.js';
 import { AgentHostLanguageModelProvider } from './agentHostLanguageModelProvider.js';
 import { AgentHostSessionHandler } from './agentHostSessionHandler.js';
@@ -76,6 +78,7 @@ export class AgentHostContribution extends Disposable implements IWorkbenchContr
 		@IStorageService private readonly _storageService: IStorageService,
 		@IAgentPluginService private readonly _agentPluginService: IAgentPluginService,
 		@IPromptsService private readonly _promptsService: IPromptsService,
+		@IFileService private readonly _fileService: IFileService,
 		@IWorkbenchEnvironmentService environmentService: IWorkbenchEnvironmentService,
 	) {
 		super();
@@ -186,7 +189,7 @@ export class AgentHostContribution extends Disposable implements IWorkbenchContr
 
 		// Customization disable provider + item provider + bundler + observable
 		const syncProvider = store.add(new AgentCustomizationSyncProvider(sessionType, this._storageService));
-		const itemProvider = store.add(new LocalAgentHostCustomizationItemProvider(this._promptsService, sessionType, syncProvider));
+		const itemProvider = store.add(new AgentCustomizationItemProvider(agent, this._loggedConnection!, 'local', this._fileService, this._logService));
 		const bundler = store.add(this._instantiationService.createInstance(SyncedCustomizationBundler, sessionType));
 		// Distinguish from the extension-host Copilot CLI harness, which
 		// registers under the same `Copilot CLI` displayName via the chat
diff --git a/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostLocalCustomizations.ts b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostLocalCustomizations.ts
index 39461a4ce69df..a1f2a142f2af8 100644
--- a/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostLocalCustomizations.ts
+++ b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostLocalCustomizations.ts
@@ -4,21 +4,16 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { CancellationToken } from '../../../../../../base/common/cancellation.js';
-import { Emitter, Event } from '../../../../../../base/common/event.js';
-import { Disposable } from '../../../../../../base/common/lifecycle.js';
-import { ResourceMap } from '../../../../../../base/common/map.js';
-import { basename, isEqualOrParent } from '../../../../../../base/common/resources.js';
+import { isEqualOrParent } from '../../../../../../base/common/resources.js';
 import { URI } from '../../../../../../base/common/uri.js';
 import { type URI as ProtocolURI } from '../../../../../../platform/agentHost/common/state/protocol/state.js';
 import { type CustomizationRef } from '../../../../../../platform/agentHost/common/state/sessionState.js';
 import { AICustomizationPromptsStorage, BUILTIN_STORAGE } from '../../../common/aiCustomizationWorkspaceService.js';
 import { PromptsType } from '../../../common/promptSyntax/promptTypes.js';
 import { IPromptPath, IPromptsService, matchesSessionType, PromptsStorage } from '../../../common/promptSyntax/service/promptsService.js';
-import { type ICustomizationSyncProvider, type ICustomizationItem, type ICustomizationItemProvider } from '../../../common/customizationHarnessService.js';
+import { type ICustomizationSyncProvider } from '../../../common/customizationHarnessService.js';
 import { IAgentPluginService } from '../../../common/plugins/agentPluginService.js';
-import { getFriendlyName } from '../../aiCustomization/aiCustomizationItemSource.js';
 import type { SyncedCustomizationBundler } from './syncedCustomizationBundler.js';
-import { getSkillFolderName } from '../../../common/promptSyntax/config/promptFileLocations.js';
 
 /**
  * Prompt types that participate in auto-sync to an agent host harness.
@@ -39,8 +34,6 @@ export const SYNCABLE_PROMPT_TYPES: readonly PromptsType[] = [
  * instructions, and agents available as the local VS Code client.
  */
 export const SYNCABLE_STORAGE_SOURCES: readonly PromptsStorage[] = [
-	PromptsStorage.local,
-	PromptsStorage.user,
 	PromptsStorage.plugin,
 	PromptsStorage.extension,
 ];
@@ -126,80 +119,6 @@ export async function enumerateLocalCustomizationsForHarness(
 	return result;
 }
 
-/**
- * {@link ICustomizationItemProvider} that surfaces an agent host
- * harness's local customizations as items in the AI Customization view.
- *
- * Each enumerated file is emitted as an {@link ICustomizationItem} with
- * `enabled = !syncProvider.isDisabled(uri)`, so the standard disable
- * affordance in the list widget reflects (and toggles) the
- * per-harness opt-out.
- */
-export class LocalAgentHostCustomizationItemProvider extends Disposable implements ICustomizationItemProvider {
-	private readonly _onDidChange = this._register(new Emitter<void>());
-	readonly onDidChange: Event<void> = this._onDidChange.event;
-
-	constructor(
-		private readonly _promptsService: IPromptsService,
-		private readonly _sessionType: string,
-		private readonly _syncProvider: ICustomizationSyncProvider,
-	) {
-		super();
-		this._register(this._syncProvider.onDidChange(() => this._onDidChange.fire()));
-		this._register(Event.any(
-			this._promptsService.onDidChangeCustomAgents,
-			this._promptsService.onDidChangeSlashCommands,
-			this._promptsService.onDidChangeSkills,
-			this._promptsService.onDidChangeInstructions,
-		)(() => this._onDidChange.fire()));
-	}
-
-	async provideChatSessionCustomizations(token: CancellationToken): Promise<ICustomizationItem[]> {
-		const [enumerated, skills] = await Promise.all([
-			enumerateLocalCustomizationsForHarness(this._promptsService, this._syncProvider, this._sessionType, token),
-			this._promptsService.findAgentSkills(token),
-		]);
-		if (token.isCancellationRequested) {
-			return [];
-		}
-		// Skill files are conventionally named SKILL.md inside a per-skill
-		// folder, so the filename is not a useful display name. Look up the
-		// parsed skill metadata (name + description from frontmatter) and
-		// fall back to the parent folder name when a skill failed to parse.
-		const skillByUri = new ResourceMap<{ name: string; description: string | undefined; userInvocable?: boolean }>();
-		for (const skill of skills ?? []) {
-			skillByUri.set(skill.uri, { name: skill.name, description: skill.description, userInvocable: skill.userInvocable });
-		}
-		return enumerated.map(file => {
-			let name: string;
-			let description: string | undefined;
-			let userInvocable: boolean | undefined;
-			if (file.type === PromptsType.skill) {
-				const parsed = skillByUri.get(file.uri);
-				name = parsed?.name ?? getSkillFolderName(file.uri);
-				description = parsed?.description;
-				userInvocable = parsed?.userInvocable;
-			} else {
-				name = getFriendlyName(basename(file.uri));
-			}
-			return {
-				uri: file.uri,
-				type: file.type,
-				name,
-				description,
-				// Cast through the wider storage union: built-in skills use
-				// `BUILTIN_STORAGE`, which is not a `PromptsStorage` enum
-				// member but is recognized by the AI Customization view.
-				storage: file.storage as PromptsStorage,
-				enabled: !file.disabled,
-				extensionId: file.extensionId,
-				pluginUri: file.pluginUri,
-				userInvocable
-			};
-		});
-	}
-}
-
 /**
  * Resolves the customization refs to include in an `activeClientChanged`
  * message.
diff --git a/src/vs/workbench/contrib/chat/test/browser/agentSessions/enumerateLocalCustomizationsForHarness.test.ts b/src/vs/workbench/contrib/chat/test/browser/agentSessions/enumerateLocalCustomizationsForHarness.test.ts
index 49a7ecb0c56ec..6720d2bb784ee 100644
--- a/src/vs/workbench/contrib/chat/test/browser/agentSessions/enumerateLocalCustomizationsForHarness.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/agentSessions/enumerateLocalCustomizationsForHarness.test.ts
@@ -57,18 +57,18 @@ suite('enumerateLocalCustomizationsForHarness', () => {
 		}]);
 	});
 
-	test('combines core storage entries with built-in skills', async () => {
+	test('combines extension storage entries with built-in skills', async () => {
 		const userAgent = URI.file('/user/agents/foo.agent.md');
 		const builtinSkill = URI.file('/builtin/merge/SKILL.md');
 		const promptsService = makePromptsService(new Map([
-			[`${PromptsType.agent}/${PromptsStorage.user}`, [makePromptPath(userAgent, PromptsType.agent, PromptsStorage.user)]],
+			[`${PromptsType.agent}/${PromptsStorage.extension}`, [makePromptPath(userAgent, PromptsType.agent, PromptsStorage.extension)]],
 			[`${PromptsType.skill}/${BUILTIN_STORAGE}`, [makePromptPath(builtinSkill, PromptsType.skill, BUILTIN_STORAGE as unknown as PromptsStorage)]],
 		]));
 
 		const result = await enumerateLocalCustomizationsForHarness(promptsService, new FakeSyncProvider(), SessionType.CopilotCLI, CancellationToken.None);
 
 		assert.deepStrictEqual(result.map((e: { uri: URI; type: PromptsType; storage: unknown; disabled: boolean }) => ({ uri: e.uri.toString(), type: e.type, storage: e.storage, disabled: e.disabled })), [
-			{ uri: userAgent.toString(), type: PromptsType.agent, storage: PromptsStorage.user, disabled: false },
+			{ uri: userAgent.toString(), type: PromptsType.agent, storage: PromptsStorage.extension, disabled: false },
 			{ uri: builtinSkill.toString(), type: PromptsType.skill, storage: BUILTIN_STORAGE, disabled: false },
 		]);
 	});
diff --git a/src/vs/workbench/contrib/chat/test/browser/agentSessions/resolveCustomizationRefs.test.ts b/src/vs/workbench/contrib/chat/test/browser/agentSessions/resolveCustomizationRefs.test.ts
index ccac5217dc7af..7040cc05e8640 100644
--- a/src/vs/workbench/contrib/chat/test/browser/agentSessions/resolveCustomizationRefs.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/agentSessions/resolveCustomizationRefs.test.ts
@@ -113,7 +113,7 @@ suite('resolveCustomizationRefs - built-in skills', () => {
 		const userAgent = URI.file('/user/agents/foo.agent.md');
 		const builtin = URI.file('/builtin/merge/SKILL.md');
 		const promptsService = makePromptsService(new Map([
-			[`${PromptsType.agent}/${PromptsStorage.user}`, [makePromptPath(userAgent, PromptsType.agent, PromptsStorage.user)]],
+			[`${PromptsType.agent}/${PromptsStorage.extension}`, [makePromptPath(userAgent, PromptsType.agent, PromptsStorage.extension)]],
 			[`${PromptsType.skill}/${BUILTIN_STORAGE}`, [makePromptPath(builtin, PromptsType.skill, BUILTIN_STORAGE as unknown as PromptsStorage)]],
 		]));
 		const bundler = new FakeBundler();

From cb9d6588c507689078ee6d2c716c537bddac18df Mon Sep 17 00:00:00 2001
From: BeniBenj <besimmonds@microsoft.com>
Date: Wed, 13 May 2026 17:57:57 +0200
Subject: [PATCH 17/27] update context keys

---
 src/vs/workbench/browser/parts/editor/editor.contribution.ts | 2 +-
 src/vs/workbench/contrib/chat/common/constants.ts            | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/vs/workbench/browser/parts/editor/editor.contribution.ts b/src/vs/workbench/browser/parts/editor/editor.contribution.ts
index f7f69c514bea5..55b2e78777932 100644
--- a/src/vs/workbench/browser/parts/editor/editor.contribution.ts
+++ b/src/vs/workbench/browser/parts/editor/editor.contribution.ts
@@ -424,7 +424,7 @@ MenuRegistry.appendMenuItem(MenuId.EditorTitle, { command: { id: TOGGLE_DIFF_SID
 MenuRegistry.appendMenuItem(MenuId.EditorTitle, { command: { id: SHOW_EDITORS_IN_GROUP, title: localize('showOpenedEditors', "Show Opened Editors") }, group: '3_open', order: 10, when: EditorPartModalContext.toNegated() /* not applicable to modal editor */ });
 MenuRegistry.appendMenuItem(MenuId.EditorTitle, { command: { id: CLOSE_EDITORS_IN_GROUP_COMMAND_ID, title: localize('closeAll', "Close All") }, group: '5_close', order: 10, when: EditorPartModalContext.toNegated() /* not applicable to modal editor */ });
 MenuRegistry.appendMenuItem(MenuId.EditorTitle, { command: { id: CLOSE_SAVED_EDITORS_COMMAND_ID, title: localize('closeAllSaved', "Close Saved") }, group: '5_close', order: 20, when: EditorPartModalContext.toNegated() /* not applicable to modal editor */ });
-MenuRegistry.appendMenuItem(MenuId.EditorTitle, { command: { id: TOGGLE_KEEP_EDITORS_COMMAND_ID, title: localize('togglePreviewMode', "Enable Preview Editors"), toggled: ContextKeyExpr.has('config.workbench.editor.enablePreview') }, group: '7_settings', order: 10 });
+MenuRegistry.appendMenuItem(MenuId.EditorTitle, { command: { id: TOGGLE_KEEP_EDITORS_COMMAND_ID, title: localize('togglePreviewMode', "Enable Preview Editors"), toggled: ContextKeyExpr.has('config.workbench.editor.enablePreview') }, group: '7_settings', order: 10, when: EditorPartModalContext.toNegated() /* not applicable to modal editor */ });
 MenuRegistry.appendMenuItem(MenuId.EditorTitle, { command: { id: TOGGLE_MAXIMIZE_EDITOR_GROUP, title: localize('maximizeGroup', "Maximize Group") }, group: '8_group_operations', order: 5, when: ContextKeyExpr.and(EditorPartMaximizedEditorGroupContext.negate(), EditorPartMultipleEditorGroupsContext) });
 MenuRegistry.appendMenuItem(MenuId.EditorTitle, { command: { id: TOGGLE_MAXIMIZE_EDITOR_GROUP, title: localize('unmaximizeGroup', "Unmaximize Group") }, group: '8_group_operations', order: 5, when: EditorPartMaximizedEditorGroupContext });
 MenuRegistry.appendMenuItem(MenuId.EditorTitle, { command: { id: TOGGLE_LOCK_GROUP_COMMAND_ID, title: localize('lockGroup', "Lock Group"), toggled: ActiveEditorGroupLockedContext }, group: '8_group_operations', order: 10, when: ContextKeyExpr.and(IsAuxiliaryWindowContext.toNegated(), EditorPartModalContext.toNegated()) /* already a primary action for aux windows, not applicable to modal editor */ });
diff --git a/src/vs/workbench/contrib/chat/common/constants.ts b/src/vs/workbench/contrib/chat/common/constants.ts
index 95cd0c2d165d3..85f19ec298f8a 100644
--- a/src/vs/workbench/contrib/chat/common/constants.ts
+++ b/src/vs/workbench/contrib/chat/common/constants.ts
@@ -8,7 +8,7 @@ import { IChatSessionsService } from './chatSessionsService.js';
 import { ServicesAccessor } from '../../../../platform/instantiation/common/instantiation.js';
 import { ContextKeyExpr, RawContextKey } from '../../../../platform/contextkey/common/contextkey.js';
 import { ChatEntitlementContextKeys } from '../../../services/chat/common/chatEntitlementService.js';
-import { IsSessionsWindowContext } from '../../../common/contextkeys.js';
+import { IsAuxiliaryWindowContext, IsSessionsWindowContext } from '../../../common/contextkeys.js';
 
 export enum ChatConfiguration {
 	AIDisabled = 'chat.disableAIFeatures',
@@ -210,6 +210,7 @@ export const OPEN_AGENTS_WINDOW_PRECONDITION = ContextKeyExpr.and(
 	ChatEntitlementContextKeys.Setup.disabledInWorkspace.negate(),
 	IsSessionsWindowContext.negate(),
 	ContextKeyExpr.has(`config.${ChatConfiguration.AgentEnabled}`),
+	IsAuxiliaryWindowContext.negate()
 );
 
 export const ChatEditorTitleMaxLength = 30;

From e97a9582d66e50e13e44797e453ca760fedd445f Mon Sep 17 00:00:00 2001
From: Anthony Kim <62267334+anthonykim1@users.noreply.github.com>
Date: Wed, 13 May 2026 08:59:35 -0700
Subject: [PATCH 18/27] Prevent alt-buffer hang in agent host terminals
 (#316177)

* Detect Agent Host alternate buffer commands

* wordings

* keep agent host shell held after early command result
---
 .../node/agentHostHeadlessTerminal.ts         |  29 +-
 .../node/agentHostTerminalManager.ts          |   9 +
 .../node/copilot/copilotShellTools.ts         | 151 +++++++---
 .../node/agentHostHeadlessTerminal.test.ts    |  20 ++
 .../node/agentHostTerminalManager.test.ts     |  61 +++++
 .../agentHost/test/node/copilotAgent.test.ts  |   1 +
 .../test/node/copilotShellTools.test.ts       | 257 +++++++++++++++++-
 7 files changed, 490 insertions(+), 38 deletions(-)

diff --git a/src/vs/platform/agentHost/node/agentHostHeadlessTerminal.ts b/src/vs/platform/agentHost/node/agentHostHeadlessTerminal.ts
index 2e7d8f4e94523..32fe36c2138d6 100644
--- a/src/vs/platform/agentHost/node/agentHostHeadlessTerminal.ts
+++ b/src/vs/platform/agentHost/node/agentHostHeadlessTerminal.ts
@@ -4,7 +4,8 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { Emitter, Event } from '../../../base/common/event.js';
-import { Disposable } from '../../../base/common/lifecycle.js';
+import { DeferredPromise } from '../../../base/common/async.js';
+import { Disposable, DisposableStore } from '../../../base/common/lifecycle.js';
 import type { ILogService } from '../../log/common/log.js';
 import pkg from '@xterm/headless';
 
@@ -91,6 +92,32 @@ export class AgentHostHeadlessTerminal extends Disposable {
 		return this._terminal.modes.bracketedPasteMode;
 	}
 
+	isInAltBuffer(): boolean {
+		return this._terminal.buffer.active === this._terminal.buffer.alternate;
+	}
+
+	createAltBufferPromise(store: DisposableStore): Promise<void> {
+		const deferred = new DeferredPromise<void>();
+		const complete = () => {
+			if (!deferred.isSettled) {
+				this._logService.debug('[AgentHostHeadlessTerminal] Detected alternate buffer entry');
+				deferred.complete();
+			}
+		};
+
+		if (this.isInAltBuffer()) {
+			complete();
+		} else {
+			store.add(this._terminal.buffer.onBufferChange(() => {
+				if (this.isInAltBuffer()) {
+					complete();
+				}
+			}));
+		}
+
+		return deferred.p;
+	}
+
 	clear(): void {
 		// xterm.clear() preserves the visible line content; emulate a terminal
 		// clear sequence so future terminal-state reads match a user-visible clear.
diff --git a/src/vs/platform/agentHost/node/agentHostTerminalManager.ts b/src/vs/platform/agentHost/node/agentHostTerminalManager.ts
index 1d745b376950f..a20c31e941cb2 100644
--- a/src/vs/platform/agentHost/node/agentHostTerminalManager.ts
+++ b/src/vs/platform/agentHost/node/agentHostTerminalManager.ts
@@ -113,6 +113,7 @@ export interface IAgentHostTerminalManager {
 	onExit(uri: string, cb: (exitCode: number) => void): IDisposable;
 	onClaimChanged(uri: string, cb: (claim: TerminalClaim) => void): IDisposable;
 	onCommandFinished(uri: string, cb: (event: ICommandFinishedEvent) => void): IDisposable;
+	createAltBufferPromise(uri: string, store: DisposableStore): Promise<void>;
 	getContent(uri: string): string | undefined;
 	getClaim(uri: string): TerminalClaim | undefined;
 	hasTerminal(uri: string): boolean;
@@ -503,6 +504,14 @@ export class AgentHostTerminalManager extends Disposable implements IAgentHostTe
 		return terminal.onCommandFinishedEmitter.event(cb);
 	}
 
+	createAltBufferPromise(uri: string, store: DisposableStore): Promise<void> {
+		const terminal = this._terminals.get(uri);
+		if (!terminal?.headlessTerminal) {
+			return new Promise(() => { });
+		}
+		return terminal.headlessTerminal.createAltBufferPromise(store);
+	}
+
 	/** Get accumulated scrollback content for a terminal as raw text. */
 	getContent(uri: string): string | undefined {
 		const terminal = this._terminals.get(uri);
diff --git a/src/vs/platform/agentHost/node/copilot/copilotShellTools.ts b/src/vs/platform/agentHost/node/copilot/copilotShellTools.ts
index f3ee37ccb25f6..c4813fa8f4780 100644
--- a/src/vs/platform/agentHost/node/copilot/copilotShellTools.ts
+++ b/src/vs/platform/agentHost/node/copilot/copilotShellTools.ts
@@ -29,6 +29,7 @@ const DEFAULT_TIMEOUT_MS = 120_000;
  * The full sentinel format is: `<<<COPILOT_SENTINEL_<uuid>_EXIT_<code>>>`.
  */
 const SENTINEL_PREFIX = '<<<COPILOT_SENTINEL_';
+const ALT_BUFFER_MESSAGE = 'The command opened the alternate buffer and is still running in the terminal. It likely launched an interactive terminal UI. Use write_bash/write_powershell to interact with it, or shutdown the shell to stop it.';
 
 /**
  * Tracks a single persistent shell instance backed by a managed PTY terminal.
@@ -101,6 +102,8 @@ export class ShellManager extends Disposable {
 	private _resolvedExecutable: Promise<string> | undefined;
 	/** Set of shell ids currently executing a command and unsafe to share. */
 	private readonly _busyShellIds = new Set<string>();
+	/** Release listeners for shells held after a tool returns while the command is still running. */
+	private readonly _heldShellReleaseListeners = new Map<string, DisposableStore>();
 
 	private readonly _onDidAssociateTerminal = this._register(new Emitter<{ toolCallId: string; terminalUri: string; displayName: string }>());
 	readonly onDidAssociateTerminal: Event<{ toolCallId: string; terminalUri: string; displayName: string }> = this._onDidAssociateTerminal.event;
@@ -114,6 +117,10 @@ export class ShellManager extends Disposable {
 		super();
 
 		this._register(toDisposable(() => {
+			for (const store of this._heldShellReleaseListeners.values()) {
+				store.dispose();
+			}
+			this._heldShellReleaseListeners.clear();
 			for (const shell of this._shells.values()) {
 				if (this._terminalManager.hasTerminal(shell.terminalUri)) {
 					this._terminalManager.disposeTerminal(shell.terminalUri);
@@ -212,6 +219,22 @@ export class ShellManager extends Disposable {
 		};
 	}
 
+	holdShellUntilCommandFinishes(shell: IManagedShell): void {
+		if (this._heldShellReleaseListeners.has(shell.id)) {
+			return;
+		}
+
+		const store = new DisposableStore();
+		const release = () => {
+			this._busyShellIds.delete(shell.id);
+			this._heldShellReleaseListeners.delete(shell.id);
+			store.dispose();
+		};
+		store.add(this._terminalManager.onCommandFinished(shell.terminalUri, release));
+		store.add(this._terminalManager.onExit(shell.terminalUri, release));
+		this._heldShellReleaseListeners.set(shell.id, store);
+	}
+
 	private _trackToolCall(toolCallId: string, shellId: string): void {
 		this._toolCallShells.set(toolCallId, shellId);
 		const shell = this._shells.get(shellId);
@@ -248,6 +271,8 @@ export class ShellManager extends Disposable {
 		if (!shell) {
 			return false;
 		}
+		this._heldShellReleaseListeners.get(id)?.dispose();
+		this._heldShellReleaseListeners.delete(id);
 		this._terminalManager.disposeTerminal(shell.terminalUri);
 		this._shells.delete(id);
 		this._busyShellIds.delete(id);
@@ -323,6 +348,11 @@ function prepareOutputForModel(rawOutput: string): string {
 // Tool implementations
 // ---------------------------------------------------------------------------
 
+interface IShellExecutionResult {
+	readonly toolResult: ToolResultObject;
+	readonly keepShellBusy?: boolean;
+}
+
 function makeSuccessResult(text: string): ToolResultObject {
 	return { textResultForLlm: text, resultType: 'success' };
 }
@@ -331,19 +361,47 @@ function makeFailureResult(text: string, error?: string): ToolResultObject {
 	return { textResultForLlm: text, resultType: 'failure', error };
 }
 
+function makeExecutionResult(toolResult: ToolResultObject, options?: { keepShellBusy?: boolean }): IShellExecutionResult {
+	return { toolResult, keepShellBusy: options?.keepShellBusy };
+}
+
+function makeBackgroundExecutionResult(text: string): IShellExecutionResult {
+	return makeExecutionResult(makeSuccessResult(text), { keepShellBusy: true });
+}
+
+function makeAltBufferExecutionResult(): IShellExecutionResult {
+	return makeExecutionResult(makeFailureResult(ALT_BUFFER_MESSAGE, 'alternateBuffer'), { keepShellBusy: true });
+}
+
+function registerAltBufferHandler(
+	shell: IManagedShell,
+	terminalManager: IAgentHostTerminalManager,
+	logService: ILogService,
+	disposables: DisposableStore,
+	finish: (result: IShellExecutionResult) => void,
+): void {
+	void terminalManager.createAltBufferPromise(shell.terminalUri, disposables).then(() => {
+		logService.info('[ShellTool] Command entered alternate buffer');
+		finish(makeAltBufferExecutionResult());
+	});
+}
+
 async function executeCommandInShell(
 	shell: IManagedShell,
 	command: string,
 	timeoutMs: number,
 	terminalManager: IAgentHostTerminalManager,
 	logService: ILogService,
-): Promise<ToolResultObject> {
+): Promise<IShellExecutionResult> {
 	const result = terminalManager.supportsCommandDetection(shell.terminalUri)
 		? await executeCommandWithShellIntegration(shell, command, timeoutMs, terminalManager, logService)
 		: await executeCommandWithSentinel(shell, command, timeoutMs, terminalManager, logService);
 	return {
 		...result,
-		textResultForLlm: `Shell ID: ${shell.id}\n${result.textResultForLlm}`,
+		toolResult: {
+			...result.toolResult,
+			textResultForLlm: `Shell ID: ${shell.id}\n${result.toolResult.textResultForLlm}`,
+		},
 	};
 }
 
@@ -358,17 +416,12 @@ async function executeCommandWithShellIntegration(
 	timeoutMs: number,
 	terminalManager: IAgentHostTerminalManager,
 	logService: ILogService,
-): Promise<ToolResultObject> {
+): Promise<IShellExecutionResult> {
 	const disposables = new DisposableStore();
 
-	await terminalManager.sendText(shell.terminalUri, `${prefixForHistorySuppression(shell.shellType)}${command}`, {
-		shouldExecute: true,
-		bracketedPasteMode: shouldUseBracketedPasteMode(command),
-	});
-
-	return new Promise<ToolResultObject>(resolve => {
+	const result = new Promise<IShellExecutionResult>(resolve => {
 		let resolved = false;
-		const finish = (result: ToolResultObject) => {
+		const finish = (result: IShellExecutionResult) => {
 			if (resolved) {
 				return;
 			}
@@ -382,23 +435,25 @@ async function executeCommandWithShellIntegration(
 			const exitCode = event.exitCode ?? 0;
 			logService.info(`[ShellTool] Command completed (shell integration) with exit code ${exitCode}`);
 			if (exitCode === 0) {
-				finish(makeSuccessResult(`Exit code: ${exitCode}\n${output}`));
+				finish(makeExecutionResult(makeSuccessResult(`Exit code: ${exitCode}\n${output}`)));
 			} else {
-				finish(makeFailureResult(`Exit code: ${exitCode}\n${output}`));
+				finish(makeExecutionResult(makeFailureResult(`Exit code: ${exitCode}\n${output}`)));
 			}
 		}));
 
+		registerAltBufferHandler(shell, terminalManager, logService, disposables, finish);
+
 		disposables.add(terminalManager.onExit(shell.terminalUri, (exitCode: number) => {
 			logService.info(`[ShellTool] Shell exited unexpectedly with code ${exitCode}`);
 			const fullContent = terminalManager.getContent(shell.terminalUri) ?? '';
 			const output = prepareOutputForModel(fullContent);
-			finish(makeFailureResult(`Shell exited with code ${exitCode}\n${output}`));
+			finish(makeExecutionResult(makeFailureResult(`Shell exited with code ${exitCode}\n${output}`)));
 		}));
 
 		disposables.add(terminalManager.onClaimChanged(shell.terminalUri, (claim) => {
 			if (claim.kind === TerminalClaimKind.Session && !claim.toolCallId) {
 				logService.info(`[ShellTool] Continuing in background (claim narrowed)`);
-				finish(makeSuccessResult('The user chose to continue this command in the background. The terminal is still running.'));
+				finish(makeBackgroundExecutionResult('The user chose to continue this command in the background. The terminal is still running.'));
 			}
 		}));
 
@@ -406,13 +461,26 @@ async function executeCommandWithShellIntegration(
 			logService.warn(`[ShellTool] Command timed out after ${timeoutMs}ms`);
 			const fullContent = terminalManager.getContent(shell.terminalUri) ?? '';
 			const output = prepareOutputForModel(fullContent);
-			finish(makeFailureResult(
+			finish(makeExecutionResult(makeFailureResult(
 				`Command timed out after ${Math.round(timeoutMs / 1000)}s. Partial output:\n${output}`,
 				'timeout',
-			));
+			)));
 		}, timeoutMs);
 		disposables.add(toDisposable(() => clearTimeout(timer)));
+
 	});
+
+	try {
+		await terminalManager.sendText(shell.terminalUri, `${prefixForHistorySuppression(shell.shellType)}${command}`, {
+			shouldExecute: true,
+			bracketedPasteMode: shouldUseBracketedPasteMode(command),
+		});
+	} catch (err) {
+		disposables.dispose();
+		throw err;
+	}
+
+	return result;
 }
 
 /**
@@ -425,7 +493,7 @@ async function executeCommandWithSentinel(
 	timeoutMs: number,
 	terminalManager: IAgentHostTerminalManager,
 	logService: ILogService,
-): Promise<ToolResultObject> {
+): Promise<IShellExecutionResult> {
 	const sentinelId = makeSentinelId();
 	const sentinelCmd = buildSentinelCommand(sentinelId, shell.shellType);
 	const disposables = new DisposableStore();
@@ -433,15 +501,9 @@ async function executeCommandWithSentinel(
 	const contentBefore = terminalManager.getContent(shell.terminalUri) ?? '';
 	const offsetBefore = contentBefore.length;
 
-	await terminalManager.sendText(shell.terminalUri, `${prefixForHistorySuppression(shell.shellType)}${command}`, {
-		shouldExecute: true,
-		bracketedPasteMode: shouldUseBracketedPasteMode(command),
-	});
-	await terminalManager.sendText(shell.terminalUri, sentinelCmd, { shouldExecute: true });
-
-	return new Promise<ToolResultObject>(resolve => {
+	const result = new Promise<IShellExecutionResult>(resolve => {
 		let resolved = false;
-		const finish = (result: ToolResultObject) => {
+		const finish = (result: IShellExecutionResult) => {
 			if (resolved) {
 				return;
 			}
@@ -462,9 +524,9 @@ async function executeCommandWithSentinel(
 				const output = prepareOutputForModel(parsed.outputBeforeSentinel);
 				logService.info(`[ShellTool] Command completed with exit code ${parsed.exitCode}`);
 				if (parsed.exitCode === 0) {
-					finish(makeSuccessResult(`Exit code: ${parsed.exitCode}\n${output}`));
+					finish(makeExecutionResult(makeSuccessResult(`Exit code: ${parsed.exitCode}\n${output}`)));
 				} else {
-					finish(makeFailureResult(`Exit code: ${parsed.exitCode}\n${output}`));
+					finish(makeExecutionResult(makeFailureResult(`Exit code: ${parsed.exitCode}\n${output}`)));
 				}
 			}
 		};
@@ -473,18 +535,20 @@ async function executeCommandWithSentinel(
 			checkForSentinel();
 		}));
 
+		registerAltBufferHandler(shell, terminalManager, logService, disposables, finish);
+
 		disposables.add(terminalManager.onExit(shell.terminalUri, (exitCode: number) => {
 			logService.info(`[ShellTool] Shell exited unexpectedly with code ${exitCode}`);
 			const fullContent = terminalManager.getContent(shell.terminalUri) ?? '';
 			const newContent = fullContent.substring(offsetBefore);
 			const output = prepareOutputForModel(newContent);
-			finish(makeFailureResult(`Shell exited with code ${exitCode}\n${output}`));
+			finish(makeExecutionResult(makeFailureResult(`Shell exited with code ${exitCode}\n${output}`)));
 		}));
 
 		disposables.add(terminalManager.onClaimChanged(shell.terminalUri, (claim) => {
 			if (claim.kind === TerminalClaimKind.Session && !claim.toolCallId) {
 				logService.info(`[ShellTool] Continuing in background (claim narrowed)`);
-				finish(makeSuccessResult('The user chose to continue this command in the background. The terminal is still running.'));
+				finish(makeBackgroundExecutionResult('The user chose to continue this command in the background. The terminal is still running.'));
 			}
 		}));
 
@@ -493,15 +557,28 @@ async function executeCommandWithSentinel(
 			const fullContent = terminalManager.getContent(shell.terminalUri) ?? '';
 			const newContent = fullContent.substring(offsetBefore);
 			const output = prepareOutputForModel(newContent);
-			finish(makeFailureResult(
+			finish(makeExecutionResult(makeFailureResult(
 				`Command timed out after ${Math.round(timeoutMs / 1000)}s. Partial output:\n${output}`,
 				'timeout',
-			));
+			)));
 		}, timeoutMs);
 		disposables.add(toDisposable(() => clearTimeout(timer)));
 
 		checkForSentinel();
 	});
+
+	try {
+		await terminalManager.sendText(shell.terminalUri, `${prefixForHistorySuppression(shell.shellType)}${command}`, {
+			shouldExecute: true,
+			bracketedPasteMode: shouldUseBracketedPasteMode(command),
+		});
+		await terminalManager.sendText(shell.terminalUri, sentinelCmd, { shouldExecute: true });
+	} catch (err) {
+		disposables.dispose();
+		throw err;
+	}
+
+	return result;
 }
 
 // ---------------------------------------------------------------------------
@@ -558,10 +635,18 @@ export async function createShellTools(
 				invocation.toolCallId,
 				invocation.toolCallId,
 			);
+			let shouldReleaseShell = true;
 			try {
-				return await executeCommandInShell(ref.object, args.command, timeoutMs, terminalManager, logService);
+				const result = await executeCommandInShell(ref.object, args.command, timeoutMs, terminalManager, logService);
+				if (result.keepShellBusy) {
+					shouldReleaseShell = false;
+					shellManager.holdShellUntilCommandFinishes(ref.object);
+				}
+				return result.toolResult;
 			} finally {
-				ref.dispose();
+				if (shouldReleaseShell) {
+					ref.dispose();
+				}
 			}
 		},
 	};
diff --git a/src/vs/platform/agentHost/test/node/agentHostHeadlessTerminal.test.ts b/src/vs/platform/agentHost/test/node/agentHostHeadlessTerminal.test.ts
index 156cc05b877f3..babd3647cd25d 100644
--- a/src/vs/platform/agentHost/test/node/agentHostHeadlessTerminal.test.ts
+++ b/src/vs/platform/agentHost/test/node/agentHostHeadlessTerminal.test.ts
@@ -82,6 +82,26 @@ suite('AgentHostHeadlessTerminal', () => {
 		assert.strictEqual(terminal.isBracketedPasteMode(), false);
 	});
 
+	test('resolves alt-buffer promise on alternate buffer entry', async () => {
+		const terminal = createTerminal();
+		const altBufferStore = disposables.add(new DisposableStore());
+		const altBufferPromise = terminal.createAltBufferPromise(altBufferStore);
+		let resolved = false;
+		void altBufferPromise.then(() => resolved = true);
+
+		assert.strictEqual(terminal.isInAltBuffer(), false);
+		await terminal.writePtyData('\x1b[?1049h');
+		assert.strictEqual(terminal.isInAltBuffer(), true);
+		await altBufferPromise;
+		assert.strictEqual(resolved, true);
+
+		await terminal.writePtyData('\x1b[?1049h');
+		assert.strictEqual(terminal.isInAltBuffer(), true);
+
+		await terminal.writePtyData('\x1b[?1049l');
+		assert.strictEqual(terminal.isInAltBuffer(), false);
+	});
+
 	test('ignores writes after dispose', async () => {
 		const terminal = createTerminal();
 		const responses: string[] = [];
diff --git a/src/vs/platform/agentHost/test/node/agentHostTerminalManager.test.ts b/src/vs/platform/agentHost/test/node/agentHostTerminalManager.test.ts
index ec3c6410f4add..cfdfbf65e9c99 100644
--- a/src/vs/platform/agentHost/test/node/agentHostTerminalManager.test.ts
+++ b/src/vs/platform/agentHost/test/node/agentHostTerminalManager.test.ts
@@ -361,6 +361,67 @@ suite('AgentHostTerminalManager – command detection integration', () => {
 		assert.deepStrictEqual(pty.writes, ['\x1b[1;4R']);
 	});
 
+	test('resolves alt-buffer promise from headless terminal data', async () => {
+		const logService = new NullLogService();
+		const stateManager = disposables.add(new AgentHostStateManager(logService));
+		const configurationService = disposables.add(new AgentConfigurationService(stateManager, logService));
+		const productService = { _serviceBrand: undefined, applicationName: 'vscode' } as IProductService;
+		const pty = new TestPty();
+		const manager = disposables.add(new TestAgentHostTerminalManager(stateManager, logService, productService, configurationService, pty));
+		const uri = 'agenthost-terminal://test/alt-buffer';
+
+		const createTerminal = manager.createTerminal({
+			terminal: uri,
+			claim: { kind: TerminalClaimKind.Client, clientId: 'test-client' },
+			cwd: process.cwd(),
+			cols: 80,
+			rows: 24,
+		}, { shell: '/bin/bash' });
+
+		await pty.dataListenerRegistered.p;
+		pty.fireData('prompt');
+		await createTerminal;
+
+		const altBufferStore = disposables.add(new DisposableStore());
+		const altBufferPromise = manager.createAltBufferPromise(uri, altBufferStore);
+
+		pty.fireData('\x1b[?1049h');
+
+		await altBufferPromise;
+	});
+
+	test('disposed alt-buffer promise listener does not resolve', async () => {
+		const logService = new NullLogService();
+		const stateManager = disposables.add(new AgentHostStateManager(logService));
+		const configurationService = disposables.add(new AgentConfigurationService(stateManager, logService));
+		const productService = { _serviceBrand: undefined, applicationName: 'vscode' } as IProductService;
+		const pty = new TestPty();
+		const manager = disposables.add(new TestAgentHostTerminalManager(stateManager, logService, productService, configurationService, pty));
+		const uri = 'agenthost-terminal://test/alt-buffer-disposed';
+
+		const createTerminal = manager.createTerminal({
+			terminal: uri,
+			claim: { kind: TerminalClaimKind.Client, clientId: 'test-client' },
+			cwd: process.cwd(),
+			cols: 80,
+			rows: 24,
+		}, { shell: '/bin/bash' });
+
+		await pty.dataListenerRegistered.p;
+		pty.fireData('prompt');
+		await createTerminal;
+
+		const altBufferStore = new DisposableStore();
+		const altBufferPromise = manager.createAltBufferPromise(uri, altBufferStore);
+		let didEnterAltBuffer = false;
+		void altBufferPromise.then(() => didEnterAltBuffer = true);
+		altBufferStore.dispose();
+		pty.fireData('\x1b[?1049h');
+		await timeout(10);
+
+		assert.strictEqual(didEnterAltBuffer, false);
+	});
+
 	test('server-handled CPR queries are stripped from client-facing data', () => {
 		function filter(data: string): string {
 			return removeServerHandledTerminalQueries(data, { pendingData: '' });
diff --git a/src/vs/platform/agentHost/test/node/copilotAgent.test.ts b/src/vs/platform/agentHost/test/node/copilotAgent.test.ts
index fc3ccc12e6332..17e695b9a3f34 100644
--- a/src/vs/platform/agentHost/test/node/copilotAgent.test.ts
+++ b/src/vs/platform/agentHost/test/node/copilotAgent.test.ts
@@ -91,6 +91,7 @@ class TestAgentHostTerminalManager implements IAgentHostTerminalManager {
 	onExit(): IDisposable { return Disposable.None; }
 	onClaimChanged(): IDisposable { return Disposable.None; }
 	onCommandFinished(): IDisposable { return Disposable.None; }
+	createAltBufferPromise(_uri: string, _store: DisposableStore): Promise<void> { return new Promise(() => { }); }
 	getContent(): string | undefined { return undefined; }
 	getClaim(): undefined { return undefined; }
 	hasTerminal(): boolean { return false; }
diff --git a/src/vs/platform/agentHost/test/node/copilotShellTools.test.ts b/src/vs/platform/agentHost/test/node/copilotShellTools.test.ts
index d27d40448e8ce..3574568adb2ed 100644
--- a/src/vs/platform/agentHost/test/node/copilotShellTools.test.ts
+++ b/src/vs/platform/agentHost/test/node/copilotShellTools.test.ts
@@ -8,7 +8,7 @@ import type { ToolInvocation, ToolResultObject } from '@github/copilot-sdk';
 import { DeferredPromise } from '../../../../base/common/async.js';
 import { URI } from '../../../../base/common/uri.js';
 import * as platform from '../../../../base/common/platform.js';
-import { Emitter } from '../../../../base/common/event.js';
+import { Emitter, Event } from '../../../../base/common/event.js';
 import { Disposable, DisposableStore, type IDisposable } from '../../../../base/common/lifecycle.js';
 import { ensureNoDisposablesAreLeakedInTestSuite } from '../../../../base/test/common/utils.js';
 import { IInstantiationService } from '../../../instantiation/common/instantiation.js';
@@ -16,7 +16,7 @@ import { InstantiationService } from '../../../instantiation/common/instantiatio
 import { ServiceCollection } from '../../../instantiation/common/serviceCollection.js';
 import { ILogService, NullLogService } from '../../../log/common/log.js';
 import type { CreateTerminalParams } from '../../common/state/protocol/commands.js';
-import type { TerminalClaim, TerminalInfo } from '../../common/state/protocol/state.js';
+import { TerminalClaimKind, type TerminalClaim, type TerminalInfo } from '../../common/state/protocol/state.js';
 import { formatTerminalText, IAgentHostTerminalManager, type ICommandFinishedEvent, type ISendTextOptions } from '../../node/agentHostTerminalManager.js';
 import { createShellTools, isMultilineCommand, ShellManager, prefixForHistorySuppression, shellTypeForExecutable } from '../../node/copilot/copilotShellTools.js';
 
@@ -31,6 +31,11 @@ class TestAgentHostTerminalManager implements IAgentHostTerminalManager {
 	commandDetectionSupported = false;
 	readonly commandFinishedListenerRegistered = new DeferredPromise<void>();
 	private readonly _onCommandFinished = new Emitter<ICommandFinishedEvent>();
+	private readonly _onExit = new Emitter<number>();
+	private readonly _onClaimChanged = new Emitter<TerminalClaim>();
+	private readonly _onDidSendText = new Emitter<void>();
+	readonly onDidSendText = this._onDidSendText.event;
+	private readonly _altBufferPromises: DeferredPromise<void>[] = [];
 
 	async createTerminal(params: CreateTerminalParams, options?: { shell?: string; preventShellHistory?: boolean; nonInteractive?: boolean }): Promise<void> {
 		this.created.push({ params, options: { ...options, shell: options?.shell ?? this.defaultShell } });
@@ -41,14 +46,28 @@ class TestAgentHostTerminalManager implements IAgentHostTerminalManager {
 	async sendText(uri: string, data: string, options: ISendTextOptions): Promise<void> {
 		this.sentTexts.push({ uri, data, options });
 		this.writeInput(uri, formatTerminalText(data, options));
+		this._onDidSendText.fire();
 	}
 	onData(): IDisposable { return Disposable.None; }
-	onExit(): IDisposable { return Disposable.None; }
-	onClaimChanged(): IDisposable { return Disposable.None; }
+	onExit(_uri: string, cb: (exitCode: number) => void): IDisposable { return this._onExit.event(cb); }
+	onClaimChanged(_uri: string, cb: (claim: TerminalClaim) => void): IDisposable { return this._onClaimChanged.event(cb); }
 	onCommandFinished(_uri: string, cb: (event: ICommandFinishedEvent) => void): IDisposable {
 		this.commandFinishedListenerRegistered.complete();
 		return this._onCommandFinished.event(cb);
 	}
+	createAltBufferPromise(_uri: string, store: DisposableStore): Promise<void> {
+		const deferred = new DeferredPromise<void>();
+		this._altBufferPromises.push(deferred);
+		store.add({
+			dispose: () => {
+				const index = this._altBufferPromises.indexOf(deferred);
+				if (index !== -1) {
+					this._altBufferPromises.splice(index, 1);
+				}
+			}
+		});
+		return deferred.p;
+	}
 	getContent(): string | undefined { return undefined; }
 	getClaim(): TerminalClaim | undefined { return undefined; }
 	hasTerminal(uri: string): boolean { return this.existingTerminalUris.has(uri); }
@@ -59,6 +78,13 @@ class TestAgentHostTerminalManager implements IAgentHostTerminalManager {
 	getTerminalState(): undefined { return undefined; }
 	async getDefaultShell(): Promise<string> { return this.defaultShell; }
 	fireCommandFinished(event: ICommandFinishedEvent): void { this._onCommandFinished.fire(event); }
+	fireExit(exitCode: number): void { this._onExit.fire(exitCode); }
+	fireClaimChanged(claim: TerminalClaim): void { this._onClaimChanged.fire(claim); }
+	fireDidEnterAltBuffer(): void {
+		for (const promise of [...this._altBufferPromises]) {
+			promise.complete();
+		}
+	}
 }
 
 suite('CopilotShellTools', () => {
@@ -78,6 +104,33 @@ suite('CopilotShellTools', () => {
 		return { instantiationService, terminalManager };
 	}
 
+	async function waitForSentTexts(terminalManager: TestAgentHostTerminalManager, count: number): Promise<void> {
+		while (terminalManager.sentTexts.length < count) {
+			const didTimeOut = await new Promise<boolean>(resolve => {
+				const disposables = new DisposableStore();
+				const listener = Event.once(terminalManager.onDidSendText)(() => {
+					disposables.dispose();
+					resolve(false);
+				});
+				disposables.add(listener);
+				const handle = setTimeout(() => {
+					disposables.dispose();
+					resolve(true);
+				}, 1000);
+				disposables.add({ dispose: () => clearTimeout(handle) });
+			});
+			if (didTimeOut) {
+				assert.fail(`Timed out waiting for ${count} sendText calls; saw ${terminalManager.sentTexts.length}`);
+			}
+		}
+	}
+
+	function markCreatedTerminalsExist(terminalManager: TestAgentHostTerminalManager): void {
+		for (const created of terminalManager.created) {
+			terminalManager.existingTerminalUris.add(created.params.terminal);
+		}
+	}
+
 	test('uses session working directory for created shells', async () => {
 		const { instantiationService, terminalManager } = createServices();
 		const worktreePath = URI.file('/workspace/worktree').fsPath;
@@ -219,6 +272,202 @@ suite('CopilotShellTools', () => {
 		assert.strictEqual(terminalManager.writes[0].data, ' echo first\recho second\r');
 	});
 
+	test('primary shell tool returns alternateBuffer when shell integration enters alt buffer', async () => {
+		const { instantiationService, terminalManager } = createServices();
+		terminalManager.commandDetectionSupported = true;
+		const shellManager = disposables.add(instantiationService.createInstance(ShellManager, URI.parse('copilot:/session-1'), undefined));
+		const tools = await createShellTools(shellManager, terminalManager, new NullLogService());
+		const bashTool = tools.find(tool => tool.name === 'bash');
+		assert.ok(bashTool);
+
+		const invocation: ToolInvocation = {
+			sessionId: 'session-1',
+			toolCallId: 'tool-1',
+			toolName: 'bash',
+			arguments: { command: 'vim README.md', timeout: 1000 },
+		};
+		const resultPromise = bashTool.handler({ command: 'vim README.md', timeout: 1000 }, invocation) as Promise<ToolResultObject>;
+		await waitForSentTexts(terminalManager, 1);
+		terminalManager.fireDidEnterAltBuffer();
+		const result = await resultPromise;
+
+		assert.strictEqual(result.resultType, 'failure');
+		assert.strictEqual(result.error, 'alternateBuffer');
+		assert.match(result.textResultForLlm, /opened the alternate buffer/);
+	});
+
+	test('primary shell tool returns alternateBuffer when sentinel fallback enters alt buffer', async () => {
+		const { instantiationService, terminalManager } = createServices();
+		const shellManager = disposables.add(instantiationService.createInstance(ShellManager, URI.parse('copilot:/session-1'), undefined));
+		const tools = await createShellTools(shellManager, terminalManager, new NullLogService());
+		const bashTool = tools.find(tool => tool.name === 'bash');
+		assert.ok(bashTool);
+
+		const invocation: ToolInvocation = {
+			sessionId: 'session-1',
+			toolCallId: 'tool-1',
+			toolName: 'bash',
+			arguments: { command: 'vim README.md', timeout: 1000 },
+		};
+		const resultPromise = bashTool.handler({ command: 'vim README.md', timeout: 1000 }, invocation) as Promise<ToolResultObject>;
+		await waitForSentTexts(terminalManager, 2);
+		terminalManager.fireDidEnterAltBuffer();
+		const result = await resultPromise;
+
+		assert.strictEqual(result.resultType, 'failure');
+		assert.strictEqual(result.error, 'alternateBuffer');
+		assert.match(result.textResultForLlm, /opened the alternate buffer/);
+	});
+
+	test('alt-buffer shell is released when command finishes', async () => {
+		const { instantiationService, terminalManager } = createServices();
+		terminalManager.commandDetectionSupported = true;
+		const shellManager = disposables.add(instantiationService.createInstance(ShellManager, URI.parse('copilot:/session-1'), undefined));
+		const tools = await createShellTools(shellManager, terminalManager, new NullLogService());
+		const bashTool = tools.find(tool => tool.name === 'bash');
+		assert.ok(bashTool);
+
+		const invocation: ToolInvocation = {
+			sessionId: 'session-1',
+			toolCallId: 'tool-1',
+			toolName: 'bash',
+			arguments: { command: 'vim README.md', timeout: 1000 },
+		};
+		const resultPromise = bashTool.handler({ command: 'vim README.md', timeout: 1000 }, invocation) as Promise<ToolResultObject>;
+		await waitForSentTexts(terminalManager, 1);
+		terminalManager.fireDidEnterAltBuffer();
+		const result = await resultPromise;
+		assert.strictEqual(result.error, 'alternateBuffer');
+		markCreatedTerminalsExist(terminalManager);
+		const shell = shellManager.listShells()[0];
+
+		terminalManager.fireCommandFinished({ commandId: 'cmd-1', exitCode: 0, command: 'vim README.md', output: '' });
+		const next = await shellManager.getOrCreateShell('bash', 'turn-2', 'tool-2');
+
+		assert.strictEqual(next.object.id, shell.id);
+		assert.strictEqual(terminalManager.created.length, 1);
+		next.dispose();
+	});
+
+	test('alt-buffer shell is not immediately reused', async () => {
+		const { instantiationService, terminalManager } = createServices();
+		terminalManager.commandDetectionSupported = true;
+		const shellManager = disposables.add(instantiationService.createInstance(ShellManager, URI.parse('copilot:/session-1'), undefined));
+		const tools = await createShellTools(shellManager, terminalManager, new NullLogService());
+		const bashTool = tools.find(tool => tool.name === 'bash');
+		assert.ok(bashTool);
+
+		const invocation: ToolInvocation = {
+			sessionId: 'session-1',
+			toolCallId: 'tool-1',
+			toolName: 'bash',
+			arguments: { command: 'vim README.md', timeout: 1000 },
+		};
+		const resultPromise = bashTool.handler({ command: 'vim README.md', timeout: 1000 }, invocation) as Promise<ToolResultObject>;
+		await waitForSentTexts(terminalManager, 1);
+		terminalManager.fireDidEnterAltBuffer();
+		const result = await resultPromise;
+		assert.strictEqual(result.error, 'alternateBuffer');
+		markCreatedTerminalsExist(terminalManager);
+		const shell = shellManager.listShells()[0];
+
+		const next = await shellManager.getOrCreateShell('bash', 'turn-2', 'tool-2');
+
+		assert.notStrictEqual(next.object.id, shell.id);
+		assert.strictEqual(terminalManager.created.length, 2);
+		next.dispose();
+	});
+
+	test('backgrounded shell is not immediately reused', async () => {
+		const { instantiationService, terminalManager } = createServices();
+		terminalManager.commandDetectionSupported = true;
+		const shellManager = disposables.add(instantiationService.createInstance(ShellManager, URI.parse('copilot:/session-1'), undefined));
+		const tools = await createShellTools(shellManager, terminalManager, new NullLogService());
+		const bashTool = tools.find(tool => tool.name === 'bash');
+		assert.ok(bashTool);
+
+		const invocation: ToolInvocation = {
+			sessionId: 'session-1',
+			toolCallId: 'tool-1',
+			toolName: 'bash',
+			arguments: { command: 'sleep 100', timeout: 1000 },
+		};
+		const resultPromise = bashTool.handler({ command: 'sleep 100', timeout: 1000 }, invocation) as Promise<ToolResultObject>;
+		await waitForSentTexts(terminalManager, 1);
+		terminalManager.fireClaimChanged({ kind: TerminalClaimKind.Session, session: 'copilot:/session-1', turnId: 'turn-1' });
+		const result = await resultPromise;
+		assert.strictEqual(result.resultType, 'success');
+		assert.match(result.textResultForLlm, /continue this command in the background/);
+		markCreatedTerminalsExist(terminalManager);
+		const shell = shellManager.listShells()[0];
+
+		const next = await shellManager.getOrCreateShell('bash', 'turn-2', 'tool-2');
+
+		assert.notStrictEqual(next.object.id, shell.id);
+		assert.strictEqual(terminalManager.created.length, 2);
+		next.dispose();
+	});
+
+	test('backgrounded shell is released when command finishes', async () => {
+		const { instantiationService, terminalManager } = createServices();
+		terminalManager.commandDetectionSupported = true;
+		const shellManager = disposables.add(instantiationService.createInstance(ShellManager, URI.parse('copilot:/session-1'), undefined));
+		const tools = await createShellTools(shellManager, terminalManager, new NullLogService());
+		const bashTool = tools.find(tool => tool.name === 'bash');
+		assert.ok(bashTool);
+
+		const invocation: ToolInvocation = {
+			sessionId: 'session-1',
+			toolCallId: 'tool-1',
+			toolName: 'bash',
+			arguments: { command: 'sleep 100', timeout: 1000 },
+		};
+		const resultPromise = bashTool.handler({ command: 'sleep 100', timeout: 1000 }, invocation) as Promise<ToolResultObject>;
+		await waitForSentTexts(terminalManager, 1);
+		terminalManager.fireClaimChanged({ kind: TerminalClaimKind.Session, session: 'copilot:/session-1', turnId: 'turn-1' });
+		const result = await resultPromise;
+		assert.strictEqual(result.resultType, 'success');
+		markCreatedTerminalsExist(terminalManager);
+		const shell = shellManager.listShells()[0];
+
+		terminalManager.fireCommandFinished({ commandId: 'cmd-1', exitCode: 0, command: 'sleep 100', output: '' });
+		const next = await shellManager.getOrCreateShell('bash', 'turn-2', 'tool-2');
+
+		assert.strictEqual(next.object.id, shell.id);
+		assert.strictEqual(terminalManager.created.length, 1);
+		next.dispose();
+	});
+
+	test('backgrounded shell is released when terminal exits', async () => {
+		const { instantiationService, terminalManager } = createServices();
+		terminalManager.commandDetectionSupported = true;
+		const shellManager = disposables.add(instantiationService.createInstance(ShellManager, URI.parse('copilot:/session-1'), undefined));
+		const tools = await createShellTools(shellManager, terminalManager, new NullLogService());
+		const bashTool = tools.find(tool => tool.name === 'bash');
+		assert.ok(bashTool);
+
+		const invocation: ToolInvocation = {
+			sessionId: 'session-1',
+			toolCallId: 'tool-1',
+			toolName: 'bash',
+			arguments: { command: 'sleep 100', timeout: 1000 },
+		};
+		const resultPromise = bashTool.handler({ command: 'sleep 100', timeout: 1000 }, invocation) as Promise<ToolResultObject>;
+		await waitForSentTexts(terminalManager, 1);
+		terminalManager.fireClaimChanged({ kind: TerminalClaimKind.Session, session: 'copilot:/session-1', turnId: 'turn-1' });
+		const result = await resultPromise;
+		assert.strictEqual(result.resultType, 'success');
+		markCreatedTerminalsExist(terminalManager);
+		const shell = shellManager.listShells()[0];
+
+		terminalManager.fireExit(0);
+		const next = await shellManager.getOrCreateShell('bash', 'turn-2', 'tool-2');
+
+		assert.strictEqual(next.object.id, shell.id);
+		assert.strictEqual(terminalManager.created.length, 1);
+		next.dispose();
+	});
+
 	test('primary shell tool only forces bracketed paste for single-line commands on macOS', async () => {
 		const { instantiationService, terminalManager } = createServices();
 		const shellManager = disposables.add(instantiationService.createInstance(ShellManager, URI.parse('copilot:/session-1'), undefined));

From dc3fcfe4766ee3a8f8e689bba1b763460804c9c9 Mon Sep 17 00:00:00 2001
From: Logan Ramos <lramos15@gmail.com>
Date: Wed, 13 May 2026 12:11:27 -0400
Subject: [PATCH 19/27] Support model pinning (#316253)

* Support model pinning

* Cleanup some hardcoded auto logic
---
 .../actionWidget/browser/actionWidget.css     |   1 +
 .../chatManagement/chatModelsWidget.ts        |  66 +++++++++--
 .../browser/widget/input/chatModelPicker.ts   | 110 +++++++++++++++---
 .../contrib/chat/common/languageModels.ts     |  80 ++++++++++++-
 .../chatModelsViewModel.test.ts               |   5 +
 .../widget/input/chatModelPicker.test.ts      |  77 +++++++++++-
 .../chat/test/common/languageModels.ts        |   6 +
 7 files changed, 316 insertions(+), 29 deletions(-)

diff --git a/src/vs/platform/actionWidget/browser/actionWidget.css b/src/vs/platform/actionWidget/browser/actionWidget.css
index 05324b5ba014e..11577533b56f0 100644
--- a/src/vs/platform/actionWidget/browser/actionWidget.css
+++ b/src/vs/platform/actionWidget/browser/actionWidget.css
@@ -89,6 +89,7 @@
 	-webkit-user-select: none;
 	user-select: none;
 	border-radius: 0;
+	pointer-events: none;
 }
 
 .action-widget .monaco-scrollable-element .monaco-list-rows .monaco-list-row.separator:hover,
diff --git a/src/vs/workbench/contrib/chat/browser/chatManagement/chatModelsWidget.ts b/src/vs/workbench/contrib/chat/browser/chatManagement/chatModelsWidget.ts
index 3204fa581e677..427681601a49d 100644
--- a/src/vs/workbench/contrib/chat/browser/chatManagement/chatModelsWidget.ts
+++ b/src/vs/workbench/contrib/chat/browser/chatManagement/chatModelsWidget.ts
@@ -797,21 +797,44 @@ class ActionsColumnRenderer extends ModelsTableColumnRenderer<IActionsColumnTemp
 	}
 
 	override renderModelElement(entry: ILanguageModelEntry, index: number, templateData: IActionsColumnTemplateData): void {
-		const configActions = this.languageModelsService.getModelConfigurationActions(entry.model.identifier);
-		if (configActions.length === 0 && !entry.model.metadata.configurationSchema) {
-			return;
+		const primaryActions: IAction[] = [];
+
+		// Auto model cannot be pinned
+		if (entry.model.metadata.id !== 'auto') {
+			primaryActions.push(this.createPinAction(entry.model.identifier));
 		}
 
+		const configActions = this.languageModelsService.getModelConfigurationActions(entry.model.identifier);
 		const secondaryActions: IAction[] = [...configActions];
 
-		// Always add "Configure..." as fallback for complex properties
-		secondaryActions.push(toAction({
-			id: 'configureModel',
-			label: localize('models.configureModel', 'Configure...'),
-			run: () => this.languageModelsService.configureModel(entry.model.identifier)
-		}));
+		if (configActions.length > 0 || entry.model.metadata.configurationSchema) {
+			secondaryActions.push(toAction({
+				id: 'configureModel',
+				label: localize('models.configureModel', 'Configure...'),
+				run: () => this.languageModelsService.configureModel(entry.model.identifier)
+			}));
+		}
+
+		templateData.actionBar.setActions(primaryActions, secondaryActions);
+	}
 
-		templateData.actionBar.setActions([], secondaryActions);
+	private createPinAction(modelIdentifier: string): IAction {
+		const isPinned = this.languageModelsService.isModelPinned(modelIdentifier);
+		return toAction({
+			id: isPinned ? `unpin.${modelIdentifier}` : `pin.${modelIdentifier}`,
+			label: isPinned
+				? localize('models.unpinModel', "Unpin Model")
+				: localize('models.pinModel', "Pin Model"),
+			class: ThemeIcon.asClassName(isPinned ? Codicon.pinned : Codicon.pin),
+			run: () => {
+				if (isPinned) {
+					this.languageModelsService.unpinModel(modelIdentifier);
+				} else {
+					this.languageModelsService.pinModel(modelIdentifier);
+				}
+				this.viewModel.refresh();
+			}
+		});
 	}
 }
 
@@ -1022,6 +1045,7 @@ export class ChatModelsWidget extends Disposable {
 		}));
 		this._register(this.chatEntitlementService.onDidChangeUsageBasedBilling(() => this.createTable()));
 		this._register(this.languageModelsService.onDidChangeLanguageModelVendors(() => this.updateAddModelsButton()));
+		this._register(this.languageModelsService.onDidChangePinnedModels(() => this.viewModel.refresh()));
 		this._register(this.contextKeyService.onDidChangeContext(e => {
 			if (e.affectsSome(new Set(['github.copilot.clientByokEnabled']))) {
 				this.updateAddModelsButton();
@@ -1190,6 +1214,28 @@ export class ChatModelsWidget extends Disposable {
 			let configureVendor: ILanguageModelProviderDescriptor | undefined;
 
 			if (selectedModelEntries.length) {
+				// Pin/unpin action — single action for all selected models
+				const pinnableEntries = selectedModelEntries.filter(e => e.model.metadata.id !== 'auto');
+				if (pinnableEntries.length > 0) {
+					const allPinned = pinnableEntries.every(e => this.languageModelsService.isModelPinned(e.model.identifier));
+					actions.push(toAction({
+						id: allPinned ? 'unpinModels' : 'pinModels',
+						label: allPinned
+							? localize('models.unpinModel', "Unpin Model")
+							: localize('models.pinModel', "Pin Model"),
+						class: ThemeIcon.asClassName(allPinned ? Codicon.pinned : Codicon.pin),
+						run: () => {
+							for (const entry of pinnableEntries) {
+								if (allPinned) {
+									this.languageModelsService.unpinModel(entry.model.identifier);
+								} else {
+									this.languageModelsService.pinModel(entry.model.identifier);
+								}
+							}
+						}
+					}));
+				}
+
 				// Show per-model configuration actions for a single model
 				if (selectedModelEntries.length === 1) {
 					const configActions = this.languageModelsService.getModelConfigurationActions(selectedModelEntries[0].model.identifier);
diff --git a/src/vs/workbench/contrib/chat/browser/widget/input/chatModelPicker.ts b/src/vs/workbench/contrib/chat/browser/widget/input/chatModelPicker.ts
index 30406a07eba5d..3c85da9b4eddd 100644
--- a/src/vs/workbench/contrib/chat/browser/widget/input/chatModelPicker.ts
+++ b/src/vs/workbench/contrib/chat/browser/widget/input/chatModelPicker.ts
@@ -9,7 +9,7 @@ import { renderMarkdown } from '../../../../../../base/browser/markdownRenderer.
 import { renderIcon } from '../../../../../../base/browser/ui/iconLabel/iconLabels.js';
 import { getBaseLayerHoverDelegate } from '../../../../../../base/browser/ui/hover/hoverDelegate2.js';
 import { getDefaultHoverDelegate } from '../../../../../../base/browser/ui/hover/hoverDelegateFactory.js';
-import { toAction } from '../../../../../../base/common/actions.js';
+import { IAction, toAction } from '../../../../../../base/common/actions.js';
 import { IStringDictionary } from '../../../../../../base/common/collections.js';
 import { Codicon } from '../../../../../../base/common/codicons.js';
 import { Emitter, Event } from '../../../../../../base/common/event.js';
@@ -181,6 +181,7 @@ function createModelItem(
 	vendorLabel?: string,
 	isUBB?: boolean,
 	ariaDescription?: string,
+	pinAction?: IAction,
 ): IActionListItem<IActionWidgetDropdownAction> {
 	const hover = model && openerService ? getModelHoverContent(model, openerService, isUBB) : undefined;
 	return {
@@ -196,10 +197,29 @@ function createModelItem(
 		badge: vendorLabel,
 		hover: hover ? { content: hover.element, disposable: hover.disposable } : undefined,
 		tooltip: action.tooltip,
+		toolbarActions: pinAction ? [pinAction] : undefined,
 		submenuActions: action.toolbarActions?.length ? action.toolbarActions : undefined,
 	};
 }
 
+/**
+ * Creates a pin/unpin toolbar action for a model item in the picker.
+ */
+function createPinAction(
+	modelIdentifier: string,
+	isPinned: boolean,
+	onTogglePin: (modelIdentifier: string, pinned: boolean) => void,
+): IAction {
+	return toAction({
+		id: `pin.${modelIdentifier}`,
+		label: isPinned
+			? localize('chat.modelPicker.unpin', "Unpin Model")
+			: localize('chat.modelPicker.pin', "Pin Model"),
+		class: ThemeIcon.asClassName(isPinned ? Codicon.pinned : Codicon.pin),
+		run: () => onTogglePin(modelIdentifier, !isPinned),
+	});
+}
+
 /**
  * Resolves a configuration property from a model's configurationSchema by group.
  * Returns the key, current value (with default fallback), and schema metadata.
@@ -361,10 +381,12 @@ export function buildModelPickerItems(
 	models: ILanguageModelChatMetadataAndIdentifier[],
 	selectedModelId: string | undefined,
 	recentModelIds: string[],
+	pinnedModelIds: string[],
 	controlModels: IStringDictionary<IModelControlEntry>,
 	currentVSCodeVersion: string,
 	updateStateType: StateType,
 	onSelect: (model: ILanguageModelChatMetadataAndIdentifier) => void,
+	onTogglePin: ((modelIdentifier: string, pinned: boolean) => void) | undefined,
 	manageSettingsUrl: string | undefined,
 	useGroupedModelPicker: boolean,
 	manageModelsAction: IActionWidgetDropdownAction | undefined,
@@ -436,7 +458,47 @@ export function buildModelPickerItems(
 				items.push(createModelItem(autoAction, autoModel, openerService, undefined, isUBB, autoAriaDesc));
 			}
 
-			// --- 2. Promoted section (selected + recently used + featured) ---
+			// Precompute group labels needed for inline badges
+			const allGroupKeys = new Set(
+				models.map(m => {
+					const info = getProviderGroupForModel(m, modelToGroup, languageModelsService!);
+					return getProviderGroupKey(info.vendor, info.groupName);
+				})
+			);
+			const showGroupLabel = allGroupKeys.size > 1;
+
+			// Helper to create a pin/unpin toolbar action for a model
+			const makePinAction = (model: ILanguageModelChatMetadataAndIdentifier) =>
+				onTogglePin ? createPinAction(model.identifier, pinnedModelIds.includes(model.identifier), onTogglePin) : undefined;
+
+			// --- 2. Pinned models ---
+			const pinnedSet = new Set(pinnedModelIds);
+			const pinnedModels: ILanguageModelChatMetadataAndIdentifier[] = [];
+			for (const id of pinnedModelIds) {
+				if (placed.has(id)) {
+					continue;
+				}
+				const model = resolveModel(id);
+				if (model && !placed.has(model.identifier)) {
+					markPlaced(model.identifier, model.metadata.id);
+					pinnedModels.push(model);
+				}
+			}
+			if (pinnedModels.length > 0) {
+				items.push({ kind: ActionListItemKind.Separator, label: localize('chat.modelPicker.pinned', "Pinned") });
+				for (const model of pinnedModels) {
+					const groupLabel = showGroupLabel
+						? getProviderGroupForModel(model, modelToGroup, languageModelsService!).groupName
+						: undefined;
+					const { action: pinnedAction, ariaDescription: pinnedAriaDesc } = createModelAction(model, selectedModelId, onSelect, languageModelsService!, undefined, showGroupLabel, isUBB);
+					items.push(createModelItem(pinnedAction, model, openerService, groupLabel, isUBB, pinnedAriaDesc, makePinAction(model)));
+				}
+			}
+
+			// --- 3. Promoted section (selected + recently used + featured) ---
+			// MRU excludes pinned models and is limited to 3 entries
+			const filteredRecentIds = recentModelIds.filter(id => !pinnedSet.has(id)).slice(0, 3);
+
 			type PromotedItem =
 				| { kind: 'available'; model: ILanguageModelChatMetadataAndIdentifier }
 				| { kind: 'unavailable'; id: string; entry: IModelControlEntry; reason: 'upgrade' | 'update' | 'admin' };
@@ -475,8 +537,8 @@ export function buildModelPickerItems(
 				tryPlaceModel(selectedModelId);
 			}
 
-			// Recently used models
-			for (const id of recentModelIds) {
+			// Recently used models (filtered to exclude pinned, limited to 3)
+			for (const id of filteredRecentIds) {
 				tryPlaceModel(id);
 			}
 
@@ -521,21 +583,13 @@ export function buildModelPickerItems(
 					return aName.localeCompare(bName);
 				});
 
-				const allGroupKeys = new Set(
-					models.map(m => {
-						const info = getProviderGroupForModel(m, modelToGroup, languageModelsService!);
-						return getProviderGroupKey(info.vendor, info.groupName);
-					})
-				);
-				const showPromotedGroupLabel = allGroupKeys.size > 1;
-
 				for (const item of promotedItems) {
 					if (item.kind === 'available') {
-						const groupLabel = showPromotedGroupLabel
+						const groupLabel = showGroupLabel
 							? getProviderGroupForModel(item.model, modelToGroup, languageModelsService!).groupName
 							: undefined;
-						const { action: promotedAction, ariaDescription: promotedAriaDesc } = createModelAction(item.model, selectedModelId, onSelect, languageModelsService!, undefined, showPromotedGroupLabel, isUBB);
-						items.push(createModelItem(promotedAction, item.model, openerService, groupLabel, isUBB, promotedAriaDesc));
+						const { action: promotedAction, ariaDescription: promotedAriaDesc } = createModelAction(item.model, selectedModelId, onSelect, languageModelsService!, undefined, showGroupLabel, isUBB);
+						items.push(createModelItem(promotedAction, item.model, openerService, groupLabel, isUBB, promotedAriaDesc, makePinAction(item.model)));
 					} else {
 						items.push(createUnavailableModelItem(item.id, item.entry, item.reason, manageSettingsUrl, updateStateType, chatEntitlementService));
 					}
@@ -627,7 +681,7 @@ export function buildModelPickerItems(
 							items.push(createUnavailableModelItem(model.metadata.id, entry, 'update', manageSettingsUrl, updateStateType, chatEntitlementService, ModelPickerSection.Other));
 						} else {
 							const { action: bucketAction, ariaDescription: bucketAriaDesc } = createModelAction(model, selectedModelId, onSelect, languageModelsService!, ModelPickerSection.Other, showGroupHeaders, isUBB);
-							items.push(createModelItem(bucketAction, model, openerService, undefined, isUBB, bucketAriaDesc));
+							items.push(createModelItem(bucketAction, model, openerService, undefined, isUBB, bucketAriaDesc, makePinAction(model)));
 						}
 					}
 				}
@@ -949,14 +1003,27 @@ export class ModelPickerWidget extends Disposable {
 			this._telemetryService.publicLog2<ChatModelPickerInteractionEvent, ChatModelPickerInteractionClassification>('chat.modelPickerInteraction', { interaction });
 		};
 		const manageSettingsUrl = this._productService.defaultChatAgent?.manageSettingsUrl;
+		const onTogglePin = (modelIdentifier: string, pinned: boolean) => {
+			if (pinned) {
+				this._languageModelsService.pinModel(modelIdentifier);
+			} else {
+				this._languageModelsService.unpinModel(modelIdentifier);
+			}
+			// Re-show the picker to reflect the updated pin state
+			this._actionWidgetService.hide();
+			this.show(anchorElement);
+		};
+
 		const items = buildModelPickerItems(
 			models,
 			this._selectedModel?.identifier,
 			this._languageModelsService.getRecentlyUsedModelIds(),
+			this._languageModelsService.getPinnedModelIds(),
 			controlModelsForTier,
 			this._productService.version,
 			this._updateService.state.type,
 			onSelect,
+			onTogglePin,
 			manageSettingsUrl,
 			this._delegate.useGroupedModelPicker(),
 			isUBB ? manageModelsAction : undefined,
@@ -968,6 +1035,16 @@ export class ModelPickerWidget extends Disposable {
 			isUBB,
 		);
 
+		// Collect all hover disposables so they are properly cleaned up when the
+		// picker is hidden. The ActionListWidget only tracks the disposable for the
+		// currently-shown hover; all other items' hover disposables would leak.
+		const hoverDisposables = new DisposableStore();
+		for (const item of items) {
+			if (item.hover?.disposable) {
+				hoverDisposables.add(item.hover.disposable);
+			}
+		}
+
 		const listOptions = {
 			// Always show the filter to allow for the secondary heading to show
 			showFilter: true,
@@ -998,6 +1075,7 @@ export class ModelPickerWidget extends Disposable {
 				action.run();
 			},
 			onHide: () => {
+				hoverDisposables.dispose();
 				this._nameButton?.setAttribute('aria-expanded', 'false');
 				if (dom.isHTMLElement(previouslyFocusedElement)) {
 					previouslyFocusedElement.focus();
diff --git a/src/vs/workbench/contrib/chat/common/languageModels.ts b/src/vs/workbench/contrib/chat/common/languageModels.ts
index aa06621056919..a14b17cf05ffb 100644
--- a/src/vs/workbench/contrib/chat/common/languageModels.ts
+++ b/src/vs/workbench/contrib/chat/common/languageModels.ts
@@ -442,6 +442,31 @@ export interface ILanguageModelsService {
 	 */
 	clearRecentlyUsedList(): void;
 
+	/**
+	 * Returns the pinned model identifiers, in the order they were pinned.
+	 */
+	getPinnedModelIds(): string[];
+
+	/**
+	 * Pins a model so it appears in the pinned section of the model picker.
+	 */
+	pinModel(modelIdentifier: string): void;
+
+	/**
+	 * Unpins a model, removing it from the pinned section.
+	 */
+	unpinModel(modelIdentifier: string): void;
+
+	/**
+	 * Returns whether the given model is pinned.
+	 */
+	isModelPinned(modelIdentifier: string): boolean;
+
+	/**
+	 * Fires when the pinned models list changes.
+	 */
+	readonly onDidChangePinnedModels: Event<void>;
+
 	/**
 	 * Returns the models from the control manifest,
 	 * separated into free and paid tiers.
@@ -558,6 +583,13 @@ export const languageModelChatProviderExtensionPoint = ExtensionsRegistry.regist
 });
 
 const CHAT_MODEL_RECENTLY_USED_STORAGE_KEY = 'chatModelRecentlyUsed';
+const CHAT_MODEL_PINNED_STORAGE_KEY = 'chatModelPinned';
+
+/**
+ * The identifier for the Auto model which dynamically routes to the best backend.
+ * Auto should never appear in user-curated lists (MRU, pinned).
+ */
+const AUTO_MODEL_IDENTIFIER = 'copilot/auto';
 const CHAT_PARTICIPANT_NAME_REGISTRY_STORAGE_KEY = 'chat.participantNameRegistry';
 const CHAT_MODELS_CONTROL_STORAGE_KEY = 'chat.modelsControl';
 
@@ -595,10 +627,14 @@ export class LanguageModelsService implements ILanguageModelsService {
 	readonly onDidChangeLanguageModels: Event<string> = this._onLanguageModelChange.event;
 
 	private _recentlyUsedModelIds: string[] = [];
+	private _pinnedModelIds: string[] = [];
 
 	private readonly _onDidChangeModelsControlManifest = this._store.add(new Emitter<IModelsControlManifest>());
 	readonly onDidChangeModelsControlManifest = this._onDidChangeModelsControlManifest.event;
 
+	private readonly _onDidChangePinnedModels = this._store.add(new Emitter<void>());
+	readonly onDidChangePinnedModels = this._onDidChangePinnedModels.event;
+
 	private _modelsControlManifest: IModelsControlManifest = { free: {}, paid: {} };
 	private _modelsControlRawResponse: IChatControlResponse['models'] | undefined;
 
@@ -621,6 +657,7 @@ export class LanguageModelsService implements ILanguageModelsService {
 	) {
 		this._hasUserSelectableModels = ChatContextKeys.languageModelsAreUserSelectable.bindTo(_contextKeyService);
 		this._recentlyUsedModelIds = this._readRecentlyUsedModels();
+		this._pinnedModelIds = this._readPinnedModels();
 		this._initChatControlData();
 
 		this._store.add(this.onDidChangeLanguageModels(() => {
@@ -1655,12 +1692,12 @@ export class LanguageModelsService implements ILanguageModelsService {
 	getRecentlyUsedModelIds(): string[] {
 		// Filter to only include models that still exist in the cache
 		return this._recentlyUsedModelIds
-			.filter(id => this._modelCache.has(id) && id !== 'copilot/auto')
+			.filter(id => this._modelCache.has(id) && id !== AUTO_MODEL_IDENTIFIER)
 			.slice(0, 4);
 	}
 
 	addToRecentlyUsedList(modelIdentifier: string): void {
-		if (modelIdentifier === 'copilot/auto') {
+		if (modelIdentifier === AUTO_MODEL_IDENTIFIER) {
 			return;
 		}
 
@@ -1685,6 +1722,45 @@ export class LanguageModelsService implements ILanguageModelsService {
 
 	//#endregion
 
+	//#region Pinned models
+
+	private _readPinnedModels(): string[] {
+		return this._storageService.getObject<string[]>(CHAT_MODEL_PINNED_STORAGE_KEY, StorageScope.PROFILE, []);
+	}
+
+	private _savePinnedModels(): void {
+		this._storageService.store(CHAT_MODEL_PINNED_STORAGE_KEY, this._pinnedModelIds, StorageScope.PROFILE, StorageTarget.USER);
+	}
+
+	getPinnedModelIds(): string[] {
+		return this._pinnedModelIds.filter(id => id !== AUTO_MODEL_IDENTIFIER && this._modelCache.has(id));
+	}
+
+	pinModel(modelIdentifier: string): void {
+		if (modelIdentifier === AUTO_MODEL_IDENTIFIER || this._pinnedModelIds.includes(modelIdentifier)) {
+			return;
+		}
+		this._pinnedModelIds.push(modelIdentifier);
+		this._savePinnedModels();
+		this._onDidChangePinnedModels.fire();
+	}
+
+	unpinModel(modelIdentifier: string): void {
+		const index = this._pinnedModelIds.indexOf(modelIdentifier);
+		if (index === -1) {
+			return;
+		}
+		this._pinnedModelIds.splice(index, 1);
+		this._savePinnedModels();
+		this._onDidChangePinnedModels.fire();
+	}
+
+	isModelPinned(modelIdentifier: string): boolean {
+		return modelIdentifier !== AUTO_MODEL_IDENTIFIER && this._pinnedModelIds.includes(modelIdentifier);
+	}
+
+	//#endregion
+
 	//#region Models control manifest
 
 	getModelsControlManifest(): IModelsControlManifest {
diff --git a/src/vs/workbench/contrib/chat/test/browser/chatManagement/chatModelsViewModel.test.ts b/src/vs/workbench/contrib/chat/test/browser/chatManagement/chatModelsViewModel.test.ts
index a2258c17d18f1..d07fe96a61836 100644
--- a/src/vs/workbench/contrib/chat/test/browser/chatManagement/chatModelsViewModel.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/chatManagement/chatModelsViewModel.test.ts
@@ -153,6 +153,11 @@ class MockLanguageModelsService implements ILanguageModelsService {
 	getRecentlyUsedModelIds(): string[] { return []; }
 	addToRecentlyUsedList(): void { }
 	clearRecentlyUsedList(): void { }
+	getPinnedModelIds(): string[] { return []; }
+	pinModel(_modelIdentifier: string): void { }
+	unpinModel(_modelIdentifier: string): void { }
+	isModelPinned(_modelIdentifier: string): boolean { return false; }
+	onDidChangePinnedModels = Event.None;
 	getModelsControlManifest(): IModelsControlManifest { return { free: {}, paid: {} }; }
 	restrictedChatParticipants = observableValue('restrictedChatParticipants', Object.create(null));
 }
diff --git a/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelPicker.test.ts b/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelPicker.test.ts
index 404d7587381a3..07f028463c898 100644
--- a/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelPicker.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelPicker.test.ts
@@ -101,6 +101,7 @@ function callBuild(
 	opts: {
 		selectedModelId?: string;
 		recentModelIds?: string[];
+		pinnedModelIds?: string[];
 		controlModels?: IStringDictionary<IModelControlEntry>;
 		entitlement?: ChatEntitlement;
 		currentVSCodeVersion?: string;
@@ -122,10 +123,12 @@ function callBuild(
 		models,
 		opts.selectedModelId,
 		opts.recentModelIds ?? [],
+		opts.pinnedModelIds ?? [],
 		opts.controlModels ?? {},
 		opts.currentVSCodeVersion ?? '1.100.0',
 		opts.updateStateType ?? StateType.Idle,
 		onSelect,
+		undefined,
 		opts.manageSettingsUrl,
 		true,
 		stubManageModelsAction,
@@ -352,7 +355,7 @@ suite('buildModelPickerItems', () => {
 		});
 		// With no selected, no recent, and no featured, both models should be in Other
 		const seps = items.filter(i => i.kind === ActionListItemKind.Separator);
-		// One separator before Other Models section (Manage Models is in the toolbar)
+		// One separator before Other Models section
 		assert.strictEqual(seps.length, 1);
 		const actions = getActionItems(items);
 		assert.strictEqual(actions[0].label, 'Auto');
@@ -601,11 +604,13 @@ suite('buildModelPickerItems', () => {
 			[auto, modelA],
 			undefined,
 			[],
+			[],
 			{},
 			'1.100.0',
 			StateType.Idle,
 			onSelect,
 			undefined,
+			undefined,
 			true,
 			undefined,
 			stubChatEntitlementService,
@@ -687,10 +692,12 @@ suite('buildModelPickerItems', () => {
 			[auto],
 			undefined,
 			['missing-model'],
+			[],
 			{ 'missing-model': { label: 'Missing Model' } as IModelControlEntry },
 			'1.100.0',
 			StateType.Idle,
 			() => { },
+			undefined,
 			'https://aka.ms/github-copilot-settings',
 			true,
 			undefined,
@@ -773,11 +780,13 @@ suite('buildModelPickerItems', () => {
 			[auto, modelA],
 			undefined,
 			[],
+			[],
 			{},
 			'1.100.0',
 			StateType.Idle,
 			onSelect,
 			undefined,
+			undefined,
 			true,
 			undefined,
 			anonymousEntitlementService,
@@ -981,6 +990,72 @@ suite('buildModelPickerItems', () => {
 		assert.ok(claudeItem);
 		assert.strictEqual(claudeItem.item?.description, undefined);
 	});
+
+	test('pinned models appear in dedicated pinned section', () => {
+		const auto = createAutoModel();
+		const modelA = createModel('gpt-4o', 'GPT-4o');
+		const modelB = createModel('claude', 'Claude');
+		const modelC = createModel('gemini', 'Gemini');
+		const items = callBuild([auto, modelA, modelB, modelC], {
+			pinnedModelIds: [modelB.identifier, modelA.identifier],
+		});
+		// Pinned section header exists
+		const pinnedSep = items.find(i => i.kind === ActionListItemKind.Separator && i.label === 'Pinned');
+		assert.ok(pinnedSep, 'Pinned separator header should exist');
+		// Pinned models appear in pin order (Claude first, then GPT-4o)
+		const pinnedSepIndex = items.indexOf(pinnedSep!);
+		const afterPinned = items.slice(pinnedSepIndex + 1);
+		const firstPinned = afterPinned.find(i => i.kind === ActionListItemKind.Action);
+		assert.strictEqual(firstPinned?.label, 'Claude');
+	});
+
+	test('pinned models do not appear in MRU/promoted section', () => {
+		const auto = createAutoModel();
+		const modelA = createModel('gpt-4o', 'GPT-4o');
+		const modelB = createModel('claude', 'Claude');
+		const items = callBuild([auto, modelA, modelB], {
+			pinnedModelIds: [modelA.identifier],
+			recentModelIds: [modelA.identifier, modelB.identifier],
+		});
+		const actions = getActionItems(items);
+		// GPT-4o should only appear once (in pinned, not again in promoted)
+		const gptItems = actions.filter(a => a.label === 'GPT-4o');
+		assert.strictEqual(gptItems.length, 1, 'Pinned model should appear exactly once');
+	});
+
+	test('MRU is capped at 3 after filtering pinned models', () => {
+		const auto = createAutoModel();
+		const models = [
+			auto,
+			createModel('m1', 'Model 1'),
+			createModel('m2', 'Model 2'),
+			createModel('m3', 'Model 3'),
+			createModel('m4', 'Model 4'),
+			createModel('m5', 'Model 5'),
+		];
+		const items = callBuild(models, {
+			recentModelIds: [models[1].identifier, models[2].identifier, models[3].identifier, models[4].identifier, models[5].identifier],
+			pinnedModelIds: [models[1].identifier],
+		});
+		// Model 1 is pinned, MRU should be Model 2, 3, 4 (capped at 3), Model 5 goes to Other
+		const actions = getActionItems(items);
+		const promotedLabels = actions
+			.filter(a => !a.isSectionToggle && a.section !== 'other' && a.item?.id !== 'manageModels' && a.label !== 'Auto' && a.label !== 'Model 1')
+			.map(a => a.label);
+		assert.ok(promotedLabels.length <= 3, 'MRU should be capped at 3');
+		assert.ok(!promotedLabels.includes('Model 1'), 'Pinned model should not be in MRU');
+	});
+
+	test('no pinned section when pinnedModelIds is empty', () => {
+		const auto = createAutoModel();
+		const modelA = createModel('gpt-4o', 'GPT-4o');
+		const items = callBuild([auto, modelA], {
+			pinnedModelIds: [],
+			recentModelIds: [modelA.identifier],
+		});
+		const pinnedSep = items.find(i => i.kind === ActionListItemKind.Separator && i.label === 'Pinned');
+		assert.strictEqual(pinnedSep, undefined, 'No pinned separator when there are no pinned models');
+	});
 });
 
 suite('formatTokenCount', () => {
diff --git a/src/vs/workbench/contrib/chat/test/common/languageModels.ts b/src/vs/workbench/contrib/chat/test/common/languageModels.ts
index a035350133b26..1e2db7b484464 100644
--- a/src/vs/workbench/contrib/chat/test/common/languageModels.ts
+++ b/src/vs/workbench/contrib/chat/test/common/languageModels.ts
@@ -26,6 +26,7 @@ export class NullLanguageModelsService implements ILanguageModelsService {
 	onDidChangeLanguageModels = Event.None;
 	onDidChangeLanguageModelVendors = Event.None;
 	onDidChangeModelsControlManifest = Event.None;
+	onDidChangePinnedModels = Event.None;
 
 	getVendors(): ILanguageModelProviderDescriptor[] {
 		return [];
@@ -109,6 +110,11 @@ export class NullLanguageModelsService implements ILanguageModelsService {
 	addToRecentlyUsedList(): void { }
 	clearRecentlyUsedList(): void { }
 
+	getPinnedModelIds(): string[] { return []; }
+	pinModel(_modelIdentifier: string): void { }
+	unpinModel(_modelIdentifier: string): void { }
+	isModelPinned(_modelIdentifier: string): boolean { return false; }
+
 	getModelsControlManifest(): IModelsControlManifest {
 		return { free: {}, paid: {} };
 	}

From 40fdd83c1374b6368e38a12e0cb99843aea4871a Mon Sep 17 00:00:00 2001
From: "vs-code-engineering[bot]"
 <122617954+vs-code-engineering[bot]@users.noreply.github.com>
Date: Wed, 13 May 2026 16:11:56 +0000
Subject: [PATCH 20/27] fix: correct off-by-one in
 PreferredExtensionsPagedModel page lookup (fixes #316033) (#316042)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The pages array excludes page 0 (pre-resolved via firstPage), so
accessing this.pages[pageIndex] is off by one — pageIndex 1 should
map to pages[0]. This caused 'Cannot read properties of undefined
(reading promise)' when resolving extensions on any page after the
first.

Co-authored-by: vs-code-engineering[bot] <122617954+vs-code-engineering[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 src/vs/workbench/contrib/extensions/browser/extensionsViews.ts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/vs/workbench/contrib/extensions/browser/extensionsViews.ts b/src/vs/workbench/contrib/extensions/browser/extensionsViews.ts
index cf21e94d05958..787100ba37148 100644
--- a/src/vs/workbench/contrib/extensions/browser/extensionsViews.ts
+++ b/src/vs/workbench/contrib/extensions/browser/extensionsViews.ts
@@ -1630,7 +1630,8 @@ export class PreferredExtensionsPagedModel implements IPagedModel<IExtension> {
 
 		const indexInPagedModel = index - this.preferredExtensions.length + this.resolvedGalleryExtensionsFromQuery.length;
 		const pageIndex = Math.floor(indexInPagedModel / this.pager.pageSize);
-		const page = this.pages[pageIndex];
+		// pages array excludes page 0 (pre-resolved via firstPage), so adjust index
+		const page = this.pages[pageIndex - 1];
 
 		if (!page.promise) {
 			page.cts = new CancellationTokenSource();

From 50603358437987a34149565ff0474e7c795ec689 Mon Sep 17 00:00:00 2001
From: Megan Rogge <merogge@microsoft.com>
Date: Wed, 13 May 2026 13:01:44 -0400
Subject: [PATCH 21/27] Set COPILOT_AGENT env var in agent terminals (#316267)

Fixes #311734

Set COPILOT_AGENT=1 in agent terminal sessions so CLI tools can
detect they are running inside an AI agent and adapt their output
(e.g. JSON instead of ANSI, disable interactive prompts, skip
animations). This follows the same pattern as other agents
(CLAUDE_CODE, CURSOR_AGENT, etc.).

Co-authored-by: Megan Rogge <meganrogge@Megans-MacBook-Pro.local>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../chatAgentTools/browser/toolTerminalCreator.ts            | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/toolTerminalCreator.ts b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/toolTerminalCreator.ts
index e97b601337931..82fc56c6669fa 100644
--- a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/toolTerminalCreator.ts
+++ b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/toolTerminalCreator.ts
@@ -148,6 +148,11 @@ export class ToolTerminalCreator {
 		const shellPath = isString(shellOrProfile) ? shellOrProfile : shellOrProfile.path;
 
 		const env: Record<string, string> = {
+			// Let CLI tools detect that they are running inside an AI agent.
+			// This allows programs to adapt their output (e.g. JSON instead of
+			// ANSI, disable interactive prompts, skip animations).
+			// See https://github.com/microsoft/vscode/issues/311734
+			COPILOT_AGENT: '1',
 			// Avoid making `git diff` interactive when called from copilot
 			GIT_PAGER: 'cat',
 			// Prevent git from opening an editor for merge commits

From 44ea3384e9cd8147ee3f30c58cee0290bd882b25 Mon Sep 17 00:00:00 2001
From: Logan Ramos <lramos15@gmail.com>
Date: Wed, 13 May 2026 13:14:46 -0400
Subject: [PATCH 22/27] Fix missing separator (#316270)

---
 .../contrib/chat/browser/widget/input/chatModelPicker.ts       | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/vs/workbench/contrib/chat/browser/widget/input/chatModelPicker.ts b/src/vs/workbench/contrib/chat/browser/widget/input/chatModelPicker.ts
index 3c85da9b4eddd..c897eb39ac5c5 100644
--- a/src/vs/workbench/contrib/chat/browser/widget/input/chatModelPicker.ts
+++ b/src/vs/workbench/contrib/chat/browser/widget/input/chatModelPicker.ts
@@ -572,6 +572,9 @@ export function buildModelPickerItems(
 			// Promoted models show their provider group name inline only when more
 			// than one provider group is configured across all models.
 			if (promotedItems.length > 0) {
+				if (items.length > 0) {
+					items.push({ kind: ActionListItemKind.Separator });
+				}
 				promotedItems.sort((a, b) => {
 					const aAvail = a.kind === 'available' ? 0 : 1;
 					const bAvail = b.kind === 'available' ? 0 : 1;

From 7b65828ff2f41333962864855a6511e70a643329 Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Wed, 13 May 2026 10:33:11 -0700
Subject: [PATCH 23/27] Bump protobufjs from 7.5.5 to 7.5.8 in
 /extensions/copilot (#316074)

Bumps [protobufjs](https://github.com/protobufjs/protobuf.js) from 7.5.5 to 7.5.8.
- [Release notes](https://github.com/protobufjs/protobuf.js/releases)
- [Changelog](https://github.com/protobufjs/protobuf.js/blob/protobufjs-v7.5.8/CHANGELOG.md)
- [Commits](https://github.com/protobufjs/protobuf.js/compare/protobufjs-v7.5.5...protobufjs-v7.5.8)

---
updated-dependencies:
- dependency-name: protobufjs
  dependency-version: 7.5.8
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
---
 extensions/copilot/package-lock.json | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/extensions/copilot/package-lock.json b/extensions/copilot/package-lock.json
index df5570d981151..55fc005e0aab2 100644
--- a/extensions/copilot/package-lock.json
+++ b/extensions/copilot/package-lock.json
@@ -4899,9 +4899,9 @@
 			"license": "BSD-3-Clause"
 		},
 		"node_modules/@protobufjs/codegen": {
-			"version": "2.0.4",
-			"resolved": "https://registry.npmjs.org/@protobufjs/codegen/-/codegen-2.0.4.tgz",
-			"integrity": "sha512-YyFaikqM5sH0ziFZCN3xDC7zeGaB/d0IUb9CATugHWbd1FRFwWwt4ld4OYMPWu5a3Xe01mGAULCdqhMlPl29Jg==",
+			"version": "2.0.5",
+			"resolved": "https://registry.npmjs.org/@protobufjs/codegen/-/codegen-2.0.5.tgz",
+			"integrity": "sha512-zgXFLzW3Ap33e6d0Wlj4MGIm6Ce8O89n/apUaGNB/jx+hw+ruWEp7EwGUshdLKVRCxZW12fp9r40E1mQrf/34g==",
 			"license": "BSD-3-Clause"
 		},
 		"node_modules/@protobufjs/eventemitter": {
@@ -4927,9 +4927,9 @@
 			"license": "BSD-3-Clause"
 		},
 		"node_modules/@protobufjs/inquire": {
-			"version": "1.1.0",
-			"resolved": "https://registry.npmjs.org/@protobufjs/inquire/-/inquire-1.1.0.tgz",
-			"integrity": "sha512-kdSefcPdruJiFMVSbn801t4vFK7KB/5gd2fYvrxhuJYg8ILrmn9SKSX2tZdV6V+ksulWqS7aXjBcRXl3wHoD9Q==",
+			"version": "1.1.1",
+			"resolved": "https://registry.npmjs.org/@protobufjs/inquire/-/inquire-1.1.1.tgz",
+			"integrity": "sha512-mnzgDV26ueAvk7rsbt9L7bE0SuAoqyuys/sMMrmVcN5x9VsxpcG3rqAUSgDyLp0UZlmNfIbQ4fHfCtreVBk8Ew==",
 			"license": "BSD-3-Clause"
 		},
 		"node_modules/@protobufjs/path": {
@@ -14880,22 +14880,22 @@
 			"license": "MIT"
 		},
 		"node_modules/protobufjs": {
-			"version": "7.5.5",
-			"resolved": "https://registry.npmjs.org/protobufjs/-/protobufjs-7.5.5.tgz",
-			"integrity": "sha512-3wY1AxV+VBNW8Yypfd1yQY9pXnqTAN+KwQxL8iYm3/BjKYMNg4i0owhEe26PWDOMaIrzeeF98Lqd5NGz4omiIg==",
+			"version": "7.5.8",
+			"resolved": "https://registry.npmjs.org/protobufjs/-/protobufjs-7.5.8.tgz",
+			"integrity": "sha512-dvpCIeLPbXZS/Ete7yLaO7RenOdken2NHKykBXbsaGxZT0UTltcarBciw+A78SRQs9iMAAVpsYA+l8b1hTePIA==",
 			"hasInstallScript": true,
 			"license": "BSD-3-Clause",
 			"dependencies": {
 				"@protobufjs/aspromise": "^1.1.2",
 				"@protobufjs/base64": "^1.1.2",
-				"@protobufjs/codegen": "^2.0.4",
+				"@protobufjs/codegen": "^2.0.5",
 				"@protobufjs/eventemitter": "^1.1.0",
 				"@protobufjs/fetch": "^1.1.0",
 				"@protobufjs/float": "^1.0.2",
-				"@protobufjs/inquire": "^1.1.0",
+				"@protobufjs/inquire": "^1.1.1",
 				"@protobufjs/path": "^1.1.2",
 				"@protobufjs/pool": "^1.1.0",
-				"@protobufjs/utf8": "^1.1.0",
+				"@protobufjs/utf8": "^1.1.1",
 				"@types/node": ">=13.7.0",
 				"long": "^5.0.0"
 			},

From 3a58860ff3289f916d80bad31fe371ac0ffeec7c Mon Sep 17 00:00:00 2001
From: Megan Rogge <merogge@microsoft.com>
Date: Wed, 13 May 2026 14:11:19 -0400
Subject: [PATCH 24/27] run_in_terminal: promote sync command to background
 after idle silence (#316166)

---
 .../browser/tools/runInTerminalTool.ts        | 63 +++++++++++++++----
 .../terminalChatAgentToolsConfiguration.ts    | 12 ++++
 .../runInTerminalTool.test.ts                 | 29 +++++++++
 3 files changed, 91 insertions(+), 13 deletions(-)

diff --git a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/tools/runInTerminalTool.ts b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/tools/runInTerminalTool.ts
index 5ae01c0fa2073..6fb798c7c658e 100644
--- a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/tools/runInTerminalTool.ts
+++ b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/tools/runInTerminalTool.ts
@@ -4,7 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import type { IMarker as IXtermMarker } from '@xterm/xterm';
-import { DeferredPromise, timeout, type CancelablePromise } from '../../../../../../base/common/async.js';
+import { DeferredPromise, RunOnceScheduler, timeout, type CancelablePromise } from '../../../../../../base/common/async.js';
 import { CancellationToken, CancellationTokenSource } from '../../../../../../base/common/cancellation.js';
 import { Codicon } from '../../../../../../base/common/codicons.js';
 import { CancellationError } from '../../../../../../base/common/errors.js';
@@ -1483,6 +1483,7 @@ export class RunInTerminalTool extends Disposable implements IToolImpl {
 		let exitCode: number | undefined;
 		let altBufferResult: IToolResult | undefined;
 		let didTimeout = false;
+		let didIdleSilence = false;
 		let didInputNeeded = false;
 		let didSensitiveAutoCancelled = false;
 		// Covers both terminals that start as background (persistentSession) and
@@ -1622,7 +1623,7 @@ export class RunInTerminalTool extends Disposable implements IToolImpl {
 						resultText += `${outputAnalyzerMessage}\n`;
 					}
 					resultText += pollingResult.output;
-					resultText += `\n${this._buildInputNeededSteeringText(chatSessionResource, termId, /*mentionTimeout*/ false)}`;
+					resultText += `\n${this._buildInputNeededSteeringText(chatSessionResource, termId, 'none')}`;
 				} else if (pollingResult) {
 					resultText += `\n The command is still running, with output:\n`;
 					if (outputAnalyzerMessage) {
@@ -1672,7 +1673,7 @@ export class RunInTerminalTool extends Disposable implements IToolImpl {
 						));
 					}
 				});
-				const raceCandidates: Promise<{ type: 'completed'; result: ITerminalExecuteStrategyResult } | { type: 'background' } | { type: 'timeout' } | { type: 'inputNeeded' }>[] = [
+				const raceCandidates: Promise<{ type: 'completed'; result: ITerminalExecuteStrategyResult } | { type: 'background' } | { type: 'timeout' } | { type: 'inputNeeded' } | { type: 'idleSilence' }>[] = [
 					executionPromise.then(result => ({ type: 'completed' as const, result })),
 					continueInBackgroundPromise.then(() => ({ type: 'background' as const })),
 					new Promise<{ type: 'inputNeeded' }>(resolve => {
@@ -1686,8 +1687,24 @@ export class RunInTerminalTool extends Disposable implements IToolImpl {
 				if (timeoutRacePromise) {
 					raceCandidates.push(timeoutRacePromise);
 				}
-				const raceResult = await Promise.race(raceCandidates);
-				raceCleanup.dispose();
+				// Idle-silence promotion: if no terminal output arrives for N ms,
+				// hand control back to the model with the terminal ID + output
+				// collected so far. The process keeps running — model can poll,
+				// send input, or kill it. Default 60s; 0 disables.
+				const idleSilenceMs = this._configurationService.getValue<number>(TerminalChatAgentToolsSettingId.IdleSilenceTimeoutMs) ?? 60000;
+				if (idleSilenceMs > 0) {
+					const idleSilenceDeferred = new DeferredPromise<{ type: 'idleSilence' }>();
+					const idleSilenceScheduler = raceCleanup.add(new RunOnceScheduler(() => idleSilenceDeferred.complete({ type: 'idleSilence' as const }), idleSilenceMs));
+					raceCleanup.add(toolTerminal.instance.onData(() => idleSilenceScheduler.schedule()));
+					idleSilenceScheduler.schedule();
+					raceCandidates.push(idleSilenceDeferred.p);
+				}
+				let raceResult: { type: 'completed'; result: ITerminalExecuteStrategyResult } | { type: 'background' } | { type: 'timeout' } | { type: 'inputNeeded' } | { type: 'idleSilence' };
+				try {
+					raceResult = await Promise.race(raceCandidates);
+				} finally {
+					raceCleanup.dispose();
+				}
 
 				if (raceResult.type === 'inputNeeded') {
 					// Output monitor detected the terminal is waiting for input.
@@ -1722,6 +1739,18 @@ export class RunInTerminalTool extends Disposable implements IToolImpl {
 					const timeoutOutput = execution.getOutput();
 					outputLineCount = timeoutOutput ? count(timeoutOutput.trim(), '\n') + 1 : 0;
 					terminalResult = timeoutOutput ?? '';
+				} else if (raceResult.type === 'idleSilence') {
+					// No output for N ms - promote to background and hand back to model. Process keeps running.
+					this._logService.debug(`RunInTerminalTool: Idle silence reached (${idleSilenceMs}ms), promoting to background`);
+					error = 'idleSilence';
+					didIdleSilence = true;
+					isBackgroundExecution = true;
+					toolTerminal.isBackground = true;
+					this._sessionTerminalAssociations.delete(chatSessionResource);
+					await this._associateProcessIdWithSession(toolTerminal.instance, chatSessionResource, termId, toolTerminal.shellIntegrationQuality, true);
+					const idleSilenceOutput = execution.getOutput();
+					outputLineCount = idleSilenceOutput ? count(idleSilenceOutput.trim(), '\n') + 1 : 0;
+					terminalResult = idleSilenceOutput ?? '';
 				} else {
 					const executeResult = raceResult.result;
 					// Reset user input state after command execution completes
@@ -1975,12 +2004,17 @@ export class RunInTerminalTool extends Disposable implements IToolImpl {
 		if (didSensitiveAutoCancelled) {
 			resultText.push(`Note: The command in terminal ID ${termId} was prompting for a password, passphrase, or other secret. The user is unavailable (auto-approve / autopilot mode is on, so no human can focus the terminal to type a secret) and the command has been cancelled. Stop, do NOT retry the command, do NOT call ${TerminalToolId.SendToTerminal}, and do NOT call vscode_askQuestions for the secret. Tell the user to run the command interactively when they are available.\n\n`);
 		} else if (didInputNeeded) {
-			resultText.push(`Note: The command is running in terminal ID ${termId} and may be waiting for input.\n${this._buildInputNeededSteeringText(chatSessionResource, termId, /*mentionTimeout*/ false)}\n\n`);
+			resultText.push(`Note: The command is running in terminal ID ${termId} and may be waiting for input.\n${this._buildInputNeededSteeringText(chatSessionResource, termId, 'none')}\n\n`);
 		} else if (didTimeout && timeoutValue !== undefined && timeoutValue > 0) {
 			const notificationHint = shouldSendNotifications
 				? ' You will be automatically notified on your next turn when it completes.'
 				: '';
-			resultText.push(`Note: Command timed out after ${timeoutValue}ms. The command may still be running in terminal ID ${termId}.${notificationHint}\n${this._buildInputNeededSteeringText(chatSessionResource, termId, /*mentionTimeout*/ true)}\n\n`);
+			resultText.push(`Note: Command timed out after ${timeoutValue}ms. The command may still be running in terminal ID ${termId}.${notificationHint}\n${this._buildInputNeededSteeringText(chatSessionResource, termId, 'timeout')}\n\n`);
+		} else if (didIdleSilence) {
+			const notificationHint = shouldSendNotifications
+				? ' You will be automatically notified on your next turn when it completes.'
+				: '';
+			resultText.push(`Note: The command produced no new output for an extended period and was moved to background terminal ID ${termId}; the process is still running and has not been killed.${notificationHint}\n${this._buildInputNeededSteeringText(chatSessionResource, termId, 'idleSilence')}\n\n`);
 		}
 		const outputAnalyzerMessage = await this._getOutputAnalyzerMessage(exitCode, terminalResult, command, didSandboxWrapCommand);
 		if (outputAnalyzerMessage) {
@@ -2034,11 +2068,12 @@ export class RunInTerminalTool extends Disposable implements IToolImpl {
 	 *      tokens) must never be routed through `vscode_askQuestions`
 	 *      because answers to that tool are sent through the model — the
 	 *      user is told to type those values directly into the terminal.
-	 * `kill_terminal` is only advertised on the timeout branch — suggesting it
-	 * in the general case leads the model to terminate valid interactive
-	 * sessions (e.g. `npm init`) instead of driving them.
+	 * `kill_terminal` is only advertised when the command may be hung
+	 * (`'timeout'` or `'idleSilence'`) — suggesting it in the general case
+	 * leads the model to terminate valid interactive sessions (e.g.
+	 * `npm init`) instead of driving them.
 	 */
-	private _buildInputNeededSteeringText(chatSessionResource: URI, termId: string, mentionTimeout: boolean): string {
+	private _buildInputNeededSteeringText(chatSessionResource: URI, termId: string, hungHint: 'none' | 'timeout' | 'idleSilence'): string {
 		const isAutoApproved = isSessionAutoApproveLevel(chatSessionResource, this._configurationService, this._chatWidgetService, this._chatService);
 		const lines: string[] = [];
 		lines.push(`This note is not a signal to end the turn — pick one of the actions below and continue.`);
@@ -2052,8 +2087,10 @@ export class RunInTerminalTool extends Disposable implements IToolImpl {
 			lines.push(`  1. If the command may still be producing output or the shell prompt has not returned, call ${TerminalToolId.GetTerminalOutput} with id="${termId}" to continue polling. This is the default and safest action when unsure.`);
 			lines.push(`  2. Only if the output clearly ends with a real non-secret input prompt (Continue? (y/n), Enter selection, etc. — a normal shell prompt like \`$\` or \`#\` does NOT count), call the vscode_askQuestions tool to ask the user, then send each answer using ${TerminalToolId.SendToTerminal} with id="${termId}" (which returns the next few lines of output). Repeat one prompt at a time. NEVER route secret prompts (passwords, passphrases, tokens, API keys, etc.) through vscode_askQuestions — answers to that tool are sent through the model. For secret prompts, tell the user to type the value directly into the terminal and stop.`);
 		}
-		if (mentionTimeout) {
+		if (hungHint === 'timeout') {
 			lines.push(`  3. A timeout does not mean the command failed — call ${TerminalToolId.GetTerminalOutput} with id="${termId}" to continue polling. Only call ${TerminalToolId.KillTerminal} if the command is genuinely hung and you need to retry with a different approach.`);
+		} else if (hungHint === 'idleSilence') {
+			lines.push(`  3. Producing no output for an extended period does not mean the command failed — call ${TerminalToolId.GetTerminalOutput} with id="${termId}" to continue polling. Only call ${TerminalToolId.KillTerminal} if the command is genuinely hung and you need to retry with a different approach.`);
 		}
 		return lines.join('\n');
 	}
@@ -2553,7 +2590,7 @@ export class RunInTerminalTool extends Disposable implements IToolImpl {
 				}
 				lastInputNeededOutput = currentOutput;
 				lastInputNeededNotificationTime = now;
-				const inputAction = this._buildInputNeededSteeringText(chatSessionResource, termId, /*mentionTimeout*/ false);
+				const inputAction = this._buildInputNeededSteeringText(chatSessionResource, termId, 'none');
 				const message = `[Terminal ${termId} notification: command may be waiting for input — assess the output below.]\n${inputAction}\nTerminal output:\n${currentOutput}`;
 
 				this._logService.debug(`RunInTerminalTool: Input needed in background terminal ${termId}, notifying chat session`);
diff --git a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/common/terminalChatAgentToolsConfiguration.ts b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/common/terminalChatAgentToolsConfiguration.ts
index f64d76b8b6b30..46d538a42f7bb 100644
--- a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/common/terminalChatAgentToolsConfiguration.ts
+++ b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/common/terminalChatAgentToolsConfiguration.ts
@@ -25,6 +25,7 @@ export const enum TerminalChatAgentToolsSettingId {
 	AgentSandboxAdvancedRuntime = 'chat.agent.sandbox.advanced.runtime',
 	PreventShellHistory = 'chat.tools.terminal.preventShellHistory',
 	EnforceTimeoutFromModel = 'chat.tools.terminal.enforceTimeoutFromModel',
+	IdleSilenceTimeoutMs = 'chat.tools.terminal.idleSilenceTimeoutMs',
 	DetachBackgroundProcesses = 'chat.tools.terminal.detachBackgroundProcesses',
 	BackgroundNotifications = 'chat.tools.terminal.backgroundNotifications',
 	IdlePollInterval = 'chat.tools.terminal.idlePollInterval',
@@ -720,6 +721,17 @@ export const terminalChatAgentToolsConfiguration: IStringDictionary<IConfigurati
 		},
 		markdownDescription: localize('enforceTimeoutFromModel.description', "Whether to enforce the timeout value provided by the model in the run in terminal tool. When enabled, if the model provides a timeout parameter, the tool will stop tracking the command after that duration and return the output collected so far."),
 	},
+	[TerminalChatAgentToolsSettingId.IdleSilenceTimeoutMs]: {
+		restricted: true,
+		type: 'number',
+		default: 60000,
+		minimum: 0,
+		tags: ['experimental'],
+		experiment: {
+			mode: 'auto'
+		},
+		markdownDescription: localize('idleSilenceTimeoutMs.description', "Number of milliseconds the run in terminal tool will wait for new output from a synchronous command before moving it to a background terminal and returning what was collected so far. The process is not killed — the tool returns the terminal ID so the model can poll, send input, or kill it. Set to {0} to disable.", '`0`'),
+	},
 	[TerminalChatAgentToolsSettingId.DetachBackgroundProcesses]: {
 		included: false,
 		restricted: true,
diff --git a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/test/electron-browser/runInTerminalTool.test.ts b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/test/electron-browser/runInTerminalTool.test.ts
index 29d6f5716f98e..cd34c0a05c0ae 100644
--- a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/test/electron-browser/runInTerminalTool.test.ts
+++ b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/test/electron-browser/runInTerminalTool.test.ts
@@ -2427,6 +2427,35 @@ suite('RunInTerminalTool', () => {
 		});
 	});
 
+	suite('input-needed steering text', () => {
+		function buildSteeringText(hungHint: 'none' | 'timeout' | 'idleSilence'): string {
+			const sessionResource = LocalChatSessionUri.forSession('input-needed-steering-session');
+			// eslint-disable-next-line @typescript-eslint/naming-convention
+			return (runInTerminalTool as unknown as { _buildInputNeededSteeringText(s: URI, t: string, h: 'none' | 'timeout' | 'idleSilence'): string })
+				._buildInputNeededSteeringText(sessionResource, 'test-term-id', hungHint);
+		}
+
+		test('none mode does not mention timeout, idle silence, or kill_terminal', () => {
+			const text = buildSteeringText('none');
+			ok(!text.toLowerCase().includes('timeout'), 'Expected no mention of timeout in the input-needed (none) hint');
+			ok(!text.toLowerCase().includes('no output'), 'Expected no mention of idle silence in the input-needed (none) hint');
+			ok(!text.includes(TerminalToolId.KillTerminal), 'Expected kill_terminal not to be advertised in the input-needed (none) hint');
+		});
+
+		test('timeout mode advertises kill_terminal and mentions timeout', () => {
+			const text = buildSteeringText('timeout');
+			ok(text.toLowerCase().includes('timeout'), 'Expected timeout hint to mention "timeout"');
+			ok(text.includes(TerminalToolId.KillTerminal), 'Expected timeout hint to advertise kill_terminal');
+		});
+
+		test('idleSilence mode advertises kill_terminal without saying "timeout"', () => {
+			const text = buildSteeringText('idleSilence');
+			ok(!text.toLowerCase().includes('timeout'), 'Idle-silence hint must not refer to a timeout');
+			ok(text.toLowerCase().includes('no output'), 'Expected idle-silence hint to describe the no-output condition');
+			ok(text.includes(TerminalToolId.KillTerminal), 'Expected idle-silence hint to advertise kill_terminal');
+		});
+	});
+
 	suite('unique rules deduplication', () => {
 		test('should properly deduplicate rules with same sourceText in auto-approve info', async () => {
 			setAutoApprove({

From bc33377584e684a8b1ef98805e1730b229f33f61 Mon Sep 17 00:00:00 2001
From: Megan Rogge <merogge@microsoft.com>
Date: Wed, 13 May 2026 14:11:46 -0400
Subject: [PATCH 25/27] run_in_terminal: fix zsh pitfalls with shell options
 and steering text (#316134)

---
 .../terminal/common/scripts/shellIntegration-rc.zsh      | 9 +++++++++
 .../chatAgentTools/browser/toolTerminalCreator.ts        | 7 +++++++
 .../chatAgentTools/browser/tools/runInTerminalTool.ts    | 6 +++++-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/vs/workbench/contrib/terminal/common/scripts/shellIntegration-rc.zsh b/src/vs/workbench/contrib/terminal/common/scripts/shellIntegration-rc.zsh
index 4869a391ebc37..c43718e335436 100644
--- a/src/vs/workbench/contrib/terminal/common/scripts/shellIntegration-rc.zsh
+++ b/src/vs/workbench/contrib/terminal/common/scripts/shellIntegration-rc.zsh
@@ -106,6 +106,15 @@ if [ "${VSCODE_PREVENT_SHELL_HISTORY:-}" = "1" ]; then
 	builtin unset VSCODE_PREVENT_SHELL_HISTORY
 fi
 
+# Agent terminal zsh fixups: disable bang history expansion so ! in double
+# quotes does not hang on dquote>, and enable inline # comments so the
+# agent can annotate commands.
+if [ "${VSCODE_AGENT_ZSH_FIXUPS:-}" = "1" ]; then
+	builtin setopt NO_BANG_HIST
+	builtin setopt INTERACTIVE_COMMENTS
+	builtin unset VSCODE_AGENT_ZSH_FIXUPS
+fi
+
 # The property (P) and command (E) codes embed values which require escaping.
 # Backslashes are doubled. Non-alphanumeric characters are converted to escaped hex.
 __vsc_escape_value() {
diff --git a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/toolTerminalCreator.ts b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/toolTerminalCreator.ts
index 82fc56c6669fa..c468eb9c5c76f 100644
--- a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/toolTerminalCreator.ts
+++ b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/toolTerminalCreator.ts
@@ -176,6 +176,13 @@ export class ToolTerminalCreator {
 			}
 		}
 
+		// Zsh-specific fixups for agent terminals: disable bang history
+		// expansion (prevents ! in double quotes from hanging on dquote>)
+		// and enable inline # comments (lets the agent annotate commands).
+		if (isZsh(shellPath, os)) {
+			env['VSCODE_AGENT_ZSH_FIXUPS'] = '1';
+		}
+
 		const config: IShellLaunchConfig = {
 			icon: ThemeIcon.fromId(Codicon.chatSparkle.id),
 			hideFromUser: true,
diff --git a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/tools/runInTerminalTool.ts b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/tools/runInTerminalTool.ts
index 6fb798c7c658e..e7ea1507edee2 100644
--- a/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/tools/runInTerminalTool.ts
+++ b/src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/tools/runInTerminalTool.ts
@@ -260,7 +260,11 @@ function createZshModelDescription(isSandboxEnabled: boolean, allowToRunUnsandbo
 		'- Use jobs, fg, bg for job control',
 		'- Use [[ ]] for conditional tests instead of [ ]',
 		'- Prefer $() over backticks for command substitution',
-		'- Take advantage of zsh globbing features (**, extended globs)'
+		'- Take advantage of zsh globbing features (**, extended globs). Note: unmatched globs fail by default (zsh: no matches found) — use a glob qualifier like *(N) or quote the glob if it should be literal',
+		'',
+		'zsh pitfalls — these WILL cause errors or hangs:',
+		'- NEVER use bare == or === as separators (e.g. echo === triggers zsh equals expansion). Quote them: echo \'===\'',
+		'- NEVER use status as a variable name (it is read-only in zsh). Use exit_code or ret instead',
 	].join('\n');
 }
 

From d6576bc8a32be91133820c40d7ba597a342191b7 Mon Sep 17 00:00:00 2001
From: Logan Ramos <lramos15@gmail.com>
Date: Wed, 13 May 2026 14:17:30 -0400
Subject: [PATCH 26/27] Remove model picker category (#316280)

* Remove model picker category

* fix compile
---
 .../vscode-node/languageModelAccess.ts          | 13 -------------
 .../test/browser/agentHostModelPicker.test.ts   |  1 -
 .../api/common/extHostLanguageModels.ts         |  2 --
 .../agentHost/agentHostLanguageModelProvider.ts |  1 -
 .../chat/browser/defaultModelContribution.ts    | 12 +-----------
 .../contrib/chat/common/languageModels.ts       |  1 -
 .../common/widget/input/modelPickerWidget.ts    |  2 --
 .../chatManagement/chatModelsViewModel.test.ts  |  8 --------
 .../promptHeaderAutocompletion.test.ts          |  8 ++++----
 .../languageProviders/promptHovers.test.ts      | 10 +++++-----
 .../languageProviders/promptValidator.test.ts   |  6 +++---
 .../widget/input/chatModelPicker.test.ts        |  1 -
 .../input/chatModelSelectionLogic.test.ts       |  1 -
 .../chat/test/common/languageModels.test.ts     | 17 -----------------
 .../tools/builtinTools/runSubagentTool.test.ts  |  2 --
 .../vscode.proposed.chatProvider.d.ts           |  9 ---------
 16 files changed, 13 insertions(+), 81 deletions(-)

diff --git a/extensions/copilot/src/extension/conversation/vscode-node/languageModelAccess.ts b/extensions/copilot/src/extension/conversation/vscode-node/languageModelAccess.ts
index 205ef34bc1aac..d432a7e6287eb 100644
--- a/extensions/copilot/src/extension/conversation/vscode-node/languageModelAccess.ts
+++ b/extensions/copilot/src/extension/conversation/vscode-node/languageModelAccess.ts
@@ -276,17 +276,6 @@ export class LanguageModelAccess extends Disposable implements IExtensionContrib
 				modelTooltip = getModelCapabilitiesDescription(endpoint);
 			}
 
-			let modelCategory: { label: string; order: number } | undefined;
-			if (endpoint instanceof AutoChatEndpoint) {
-				modelCategory = { label: '', order: Number.MIN_SAFE_INTEGER };
-			} else if (endpoint.isPremium === undefined || this._authenticationService.copilotToken?.isFreeUser) {
-				modelCategory = { label: vscode.l10n.t("Copilot Models"), order: 0 };
-			} else if (endpoint.isPremium) {
-				modelCategory = { label: vscode.l10n.t("Premium Models"), order: 1 };
-			} else {
-				modelCategory = { label: vscode.l10n.t("Standard Models"), order: 0 };
-			}
-
 			// Counting tokens requires instantiating the tokenizers, which makes this process use a lot of memory.
 			// Let's cache the results across extension activations
 			const baseCount = await this._promptBaseCountCache.getBaseCount(endpoint);
@@ -304,7 +293,6 @@ export class LanguageModelAccess extends Disposable implements IExtensionContrib
 				const customModel = endpoint.customModel;
 				modelDetail = customModel.owner_name;
 				modelTooltip = vscode.l10n.t('{0} is contributed by {1} using {2}.', sanitizedModelName, customModel.owner_name, customModel.key_name);
-				modelCategory = { label: vscode.l10n.t("Custom Models"), order: 2 };
 			}
 
 			const session = this._authenticationService.anyGitHubSession;
@@ -322,7 +310,6 @@ export class LanguageModelAccess extends Disposable implements IExtensionContrib
 				multiplierNumeric: endpoint instanceof AutoChatEndpoint ? undefined : endpoint.multiplier,
 				priceCategory: endpoint instanceof AutoChatEndpoint ? undefined : endpoint.priceCategory,
 				detail: modelDetail,
-				category: modelCategory,
 				statusIcon: endpoint.degradationReason ? new vscode.ThemeIcon('warning') : undefined,
 				version: endpoint.version,
 				maxInputTokens: endpoint.modelMaxPromptTokens - baseCount - BaseTokensPerCompletion,
diff --git a/src/vs/sessions/contrib/providers/agentHost/test/browser/agentHostModelPicker.test.ts b/src/vs/sessions/contrib/providers/agentHost/test/browser/agentHostModelPicker.test.ts
index 924c2a0cc7877..74221ca405f0f 100644
--- a/src/vs/sessions/contrib/providers/agentHost/test/browser/agentHostModelPicker.test.ts
+++ b/src/vs/sessions/contrib/providers/agentHost/test/browser/agentHostModelPicker.test.ts
@@ -23,7 +23,6 @@ function makeModel(identifier: string): ILanguageModelChatMetadataAndIdentifier
 			maxOutputTokens: 4096,
 			isDefaultForLocation: {},
 			isUserSelectable: true,
-			modelPickerCategory: undefined,
 			targetChatSessionType: 'agent-host-copilotcli',
 		},
 	};
diff --git a/src/vs/workbench/api/common/extHostLanguageModels.ts b/src/vs/workbench/api/common/extHostLanguageModels.ts
index 17eeef6f4ab98..107cc44b4af9c 100644
--- a/src/vs/workbench/api/common/extHostLanguageModels.ts
+++ b/src/vs/workbench/api/common/extHostLanguageModels.ts
@@ -19,7 +19,6 @@ import { createDecorator } from '../../../platform/instantiation/common/instanti
 import { ILogService } from '../../../platform/log/common/log.js';
 import { Progress } from '../../../platform/progress/common/progress.js';
 import { IChatMessage, IChatResponsePart, ILanguageModelChatInfoOptions, ILanguageModelChatMetadata, ILanguageModelChatMetadataAndIdentifier, ILanguageModelChatRequestOptions } from '../../contrib/chat/common/languageModels.js';
-import { DEFAULT_MODEL_PICKER_CATEGORY } from '../../contrib/chat/common/widget/input/modelPickerWidget.js';
 import { INTERNAL_AUTH_PROVIDER_PREFIX } from '../../services/authentication/common/authentication.js';
 import { checkProposedApiEnabled, isProposedApiEnabled } from '../../services/extensions/common/extensions.js';
 import { SerializableObjectWithBuffers } from '../../services/extensions/common/proxyIdentifier.js';
@@ -235,7 +234,6 @@ export class ExtHostLanguageModels implements ExtHostLanguageModelsShape {
 					statusIcon: m.statusIcon,
 					targetChatSessionType: m.targetChatSessionType,
 					configurationSchema: m.configurationSchema as IJSONSchema | undefined,
-					modelPickerCategory: m.category ?? DEFAULT_MODEL_PICKER_CATEGORY,
 					capabilities: m.capabilities ? {
 						vision: m.capabilities.imageInput,
 						editTools: m.capabilities.editTools,
diff --git a/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostLanguageModelProvider.ts b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostLanguageModelProvider.ts
index fb00b9c855928..1b6098b3f2db3 100644
--- a/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostLanguageModelProvider.ts
+++ b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostLanguageModelProvider.ts
@@ -56,7 +56,6 @@ export class AgentHostLanguageModelProvider extends Disposable implements ILangu
 						isUserSelectable: true,
 						pricing: multiplierNumeric !== undefined ? `${multiplierNumeric}x` : undefined,
 						multiplierNumeric,
-						modelPickerCategory: undefined,
 						targetChatSessionType: this._sessionType,
 						capabilities: {
 							vision: m.supportsVision ?? false,
diff --git a/src/vs/workbench/contrib/chat/browser/defaultModelContribution.ts b/src/vs/workbench/contrib/chat/browser/defaultModelContribution.ts
index 8af7a3622b94e..253914a7495e6 100644
--- a/src/vs/workbench/contrib/chat/browser/defaultModelContribution.ts
+++ b/src/vs/workbench/contrib/chat/browser/defaultModelContribution.ts
@@ -9,7 +9,6 @@ import { IConfigurationRegistry, Extensions as ConfigurationExtensions } from '.
 import { ILogService } from '../../../../platform/log/common/log.js';
 import { Registry } from '../../../../platform/registry/common/platform.js';
 import { ILanguageModelChatMetadata, ILanguageModelsService } from '../common/languageModels.js';
-import { DEFAULT_MODEL_PICKER_CATEGORY } from '../common/widget/input/modelPickerWidget.js';
 
 const configurationRegistry = Registry.as<IConfigurationRegistry>(ConfigurationExtensions.Configuration);
 
@@ -100,16 +99,7 @@ export abstract class DefaultModelContribution extends Disposable {
 				return true;
 			});
 
-			supportedModels.sort((a, b) => {
-				const aCategory = a.metadata.modelPickerCategory ?? DEFAULT_MODEL_PICKER_CATEGORY;
-				const bCategory = b.metadata.modelPickerCategory ?? DEFAULT_MODEL_PICKER_CATEGORY;
-
-				if (aCategory.order !== bCategory.order) {
-					return aCategory.order - bCategory.order;
-				}
-
-				return a.metadata.name.localeCompare(b.metadata.name);
-			});
+			supportedModels.sort((a, b) => a.metadata.name.localeCompare(b.metadata.name));
 
 			for (const model of supportedModels) {
 				try {
diff --git a/src/vs/workbench/contrib/chat/common/languageModels.ts b/src/vs/workbench/contrib/chat/common/languageModels.ts
index a14b17cf05ffb..8784420ba31fc 100644
--- a/src/vs/workbench/contrib/chat/common/languageModels.ts
+++ b/src/vs/workbench/contrib/chat/common/languageModels.ts
@@ -203,7 +203,6 @@ export interface ILanguageModelChatMetadata {
 	readonly isDefaultForLocation: { [K in ChatAgentLocation]?: boolean };
 	readonly isUserSelectable?: boolean;
 	readonly statusIcon?: ThemeIcon;
-	readonly modelPickerCategory: { label: string; order: number } | undefined;
 	readonly auth?: {
 		readonly providerLabel: string;
 		readonly accountLabel?: string;
diff --git a/src/vs/workbench/contrib/chat/common/widget/input/modelPickerWidget.ts b/src/vs/workbench/contrib/chat/common/widget/input/modelPickerWidget.ts
index 5d5f437c1db08..57ff8b2df2fd6 100644
--- a/src/vs/workbench/contrib/chat/common/widget/input/modelPickerWidget.ts
+++ b/src/vs/workbench/contrib/chat/common/widget/input/modelPickerWidget.ts
@@ -3,6 +3,4 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import { localize } from '../../../../../../nls.js';
 
-export const DEFAULT_MODEL_PICKER_CATEGORY = { label: localize('chat.modelPicker.other', "Other Models"), order: Number.MAX_SAFE_INTEGER };
diff --git a/src/vs/workbench/contrib/chat/test/browser/chatManagement/chatModelsViewModel.test.ts b/src/vs/workbench/contrib/chat/test/browser/chatManagement/chatModelsViewModel.test.ts
index d07fe96a61836..88f674aedf0c4 100644
--- a/src/vs/workbench/contrib/chat/test/browser/chatManagement/chatModelsViewModel.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/chatManagement/chatModelsViewModel.test.ts
@@ -196,7 +196,6 @@ suite('ChatModelsViewModel', () => {
 			vendor: 'copilot',
 			maxInputTokens: 8192,
 			maxOutputTokens: 4096,
-			modelPickerCategory: { label: 'Copilot', order: 1 },
 			isUserSelectable: true,
 			capabilities: {
 				toolCalling: true,
@@ -217,7 +216,6 @@ suite('ChatModelsViewModel', () => {
 			vendor: 'copilot',
 			maxInputTokens: 8192,
 			maxOutputTokens: 4096,
-			modelPickerCategory: { label: 'Copilot', order: 1 },
 			isUserSelectable: true,
 			capabilities: {
 				toolCalling: true,
@@ -238,7 +236,6 @@ suite('ChatModelsViewModel', () => {
 			vendor: 'openai',
 			maxInputTokens: 4096,
 			maxOutputTokens: 2048,
-			modelPickerCategory: { label: 'OpenAI', order: 2 },
 			isUserSelectable: true,
 			capabilities: {
 				toolCalling: true,
@@ -259,7 +256,6 @@ suite('ChatModelsViewModel', () => {
 			vendor: 'openai',
 			maxInputTokens: 8192,
 			maxOutputTokens: 4096,
-			modelPickerCategory: { label: 'OpenAI', order: 2 },
 			isUserSelectable: false,
 			capabilities: {
 				toolCalling: false,
@@ -552,7 +548,6 @@ suite('ChatModelsViewModel', () => {
 			vendor: 'copilot',
 			maxInputTokens: 8192,
 			maxOutputTokens: 4096,
-			modelPickerCategory: { label: 'Copilot', order: 1 },
 			isUserSelectable: true,
 			capabilities: {
 				toolCalling: true,
@@ -574,7 +569,6 @@ suite('ChatModelsViewModel', () => {
 				vendor: 'copilot',
 				maxInputTokens: 8192,
 				maxOutputTokens: 4096,
-				modelPickerCategory: { label: 'Copilot', order: 1 },
 				isUserSelectable: true,
 				capabilities: {
 					toolCalling: true,
@@ -658,7 +652,6 @@ suite('ChatModelsViewModel', () => {
 			vendor: 'anthropic',
 			maxInputTokens: 100000,
 			maxOutputTokens: 4096,
-			modelPickerCategory: { label: 'Anthropic', order: 3 },
 			isUserSelectable: true,
 			capabilities: {
 				toolCalling: true,
@@ -687,7 +680,6 @@ suite('ChatModelsViewModel', () => {
 			vendor: 'azure',
 			maxInputTokens: 8192,
 			maxOutputTokens: 4096,
-			modelPickerCategory: { label: 'Azure', order: 4 },
 			isUserSelectable: true,
 			capabilities: {
 				toolCalling: true,
diff --git a/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptHeaderAutocompletion.test.ts b/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptHeaderAutocompletion.test.ts
index 93bd33b636fd6..088780a29a2d6 100644
--- a/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptHeaderAutocompletion.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptHeaderAutocompletion.test.ts
@@ -54,10 +54,10 @@ suite('PromptHeaderAutocompletion', () => {
 		instaService.set(ILanguageModelToolsService, toolService);
 
 		const testModels: ILanguageModelChatMetadata[] = [
-			{ id: 'mae-4', name: 'MAE 4', vendor: 'olama', version: '1.0', family: 'mae', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
-			{ id: 'mae-4.1', name: 'MAE 4.1', vendor: 'copilot', version: '1.0', family: 'mae', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
-			{ id: 'gpt-4', name: 'GPT 4', vendor: 'openai', version: '1.0', family: 'gpt', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: false, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
-			{ id: 'bg-agent-model', name: 'BG Agent Model', vendor: 'copilot', version: '1.0', family: 'bg', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true }, targetChatSessionType: 'background' } satisfies ILanguageModelChatMetadata,
+			{ id: 'mae-4', name: 'MAE 4', vendor: 'olama', version: '1.0', family: 'mae', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
+			{ id: 'mae-4.1', name: 'MAE 4.1', vendor: 'copilot', version: '1.0', family: 'mae', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
+			{ id: 'gpt-4', name: 'GPT 4', vendor: 'openai', version: '1.0', family: 'gpt', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: false, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
+			{ id: 'bg-agent-model', name: 'BG Agent Model', vendor: 'copilot', version: '1.0', family: 'bg', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true }, targetChatSessionType: 'background' } satisfies ILanguageModelChatMetadata,
 		];
 
 		instaService.stub(ILanguageModelsService, {
diff --git a/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptHovers.test.ts b/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptHovers.test.ts
index ccfb6f7afb9b7..bffe8dec8a346 100644
--- a/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptHovers.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptHovers.test.ts
@@ -53,12 +53,12 @@ suite('PromptHoverProvider', () => {
 		instaService.set(ILanguageModelToolsService, toolService);
 
 		const testModels: ILanguageModelChatMetadata[] = [
-			{ id: 'mae-4', name: 'MAE 4', vendor: 'olama', version: '1.0', family: 'mae', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
-			{ id: 'mae-4.1', name: 'MAE 4.1', vendor: 'copilot', version: '1.0', family: 'mae', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
+			{ id: 'mae-4', name: 'MAE 4', vendor: 'olama', version: '1.0', family: 'mae', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
+			{ id: 'mae-4.1', name: 'MAE 4.1', vendor: 'copilot', version: '1.0', family: 'mae', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
 			// Claude model equivalents
-			{ id: 'claude-sonnet-4.5', name: 'Claude Sonnet 4.5', vendor: 'copilot', version: '1.0', family: 'claude', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 200000, maxOutputTokens: 8192, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: {} } satisfies ILanguageModelChatMetadata,
-			{ id: 'claude-opus-4.6', name: 'Claude Opus 4.6', vendor: 'copilot', version: '1.0', family: 'claude', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 200000, maxOutputTokens: 8192, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: {} } satisfies ILanguageModelChatMetadata,
-			{ id: 'claude-haiku-4.5', name: 'Claude Haiku 4.5', vendor: 'copilot', version: '1.0', family: 'claude', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 200000, maxOutputTokens: 8192, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: {} } satisfies ILanguageModelChatMetadata,
+			{ id: 'claude-sonnet-4.5', name: 'Claude Sonnet 4.5', vendor: 'copilot', version: '1.0', family: 'claude', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 200000, maxOutputTokens: 8192, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: {} } satisfies ILanguageModelChatMetadata,
+			{ id: 'claude-opus-4.6', name: 'Claude Opus 4.6', vendor: 'copilot', version: '1.0', family: 'claude', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 200000, maxOutputTokens: 8192, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: {} } satisfies ILanguageModelChatMetadata,
+			{ id: 'claude-haiku-4.5', name: 'Claude Haiku 4.5', vendor: 'copilot', version: '1.0', family: 'claude', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 200000, maxOutputTokens: 8192, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: {} } satisfies ILanguageModelChatMetadata,
 		];
 
 		instaService.stub(ILanguageModelsService, {
diff --git a/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptValidator.test.ts b/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptValidator.test.ts
index 81d88c70934b6..639c09d414e99 100644
--- a/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptValidator.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptValidator.test.ts
@@ -119,9 +119,9 @@ suite('PromptValidator', () => {
 		instaService.set(ILanguageModelToolsService, toolService);
 
 		const testModels: ILanguageModelChatMetadata[] = [
-			{ id: 'mae-4', name: 'MAE 4', vendor: 'olama', version: '1.0', family: 'mae', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
-			{ id: 'mae-4.1', name: 'MAE 4.1', vendor: 'copilot', version: '1.0', family: 'mae', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
-			{ id: 'mae-3.5-turbo', name: 'MAE 3.5 Turbo', vendor: 'copilot', version: '1.0', family: 'mae', modelPickerCategory: undefined, extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata
+			{ id: 'mae-4', name: 'MAE 4', vendor: 'olama', version: '1.0', family: 'mae', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
+			{ id: 'mae-4.1', name: 'MAE 4.1', vendor: 'copilot', version: '1.0', family: 'mae', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, capabilities: { agentMode: true, toolCalling: true }, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata,
+			{ id: 'mae-3.5-turbo', name: 'MAE 3.5 Turbo', vendor: 'copilot', version: '1.0', family: 'mae', extension: new ExtensionIdentifier('a.b'), isUserSelectable: true, maxInputTokens: 8192, maxOutputTokens: 1024, isDefaultForLocation: { [ChatAgentLocation.Chat]: true } } satisfies ILanguageModelChatMetadata
 		];
 
 		instaService.stub(ILanguageModelsService, {
diff --git a/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelPicker.test.ts b/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelPicker.test.ts
index 07f028463c898..18f29d64096a7 100644
--- a/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelPicker.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelPicker.test.ts
@@ -38,7 +38,6 @@ function createModel(id: string, name: string, vendor = 'copilot'): ILanguageMod
 			maxInputTokens: 128000,
 			maxOutputTokens: 4096,
 			isDefaultForLocation: {},
-			modelPickerCategory: undefined,
 		} as ILanguageModelChatMetadata,
 	};
 }
diff --git a/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelSelectionLogic.test.ts b/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelSelectionLogic.test.ts
index 60b976a416de5..639ae66116858 100644
--- a/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelSelectionLogic.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelSelectionLogic.test.ts
@@ -59,7 +59,6 @@ function createModel(
 			maxOutputTokens: 4096,
 			isDefaultForLocation: {},
 			isUserSelectable: true,
-			modelPickerCategory: undefined,
 			capabilities: { toolCalling: true, agentMode: true },
 			...overrides,
 		} as ILanguageModelChatMetadata,
diff --git a/src/vs/workbench/contrib/chat/test/common/languageModels.test.ts b/src/vs/workbench/contrib/chat/test/common/languageModels.test.ts
index 5cc52dd5675a8..5e6c1a171556c 100644
--- a/src/vs/workbench/contrib/chat/test/common/languageModels.test.ts
+++ b/src/vs/workbench/contrib/chat/test/common/languageModels.test.ts
@@ -12,7 +12,6 @@ import { ensureNoDisposablesAreLeakedInTestSuite } from '../../../../../base/tes
 import { NullLogService } from '../../../../../platform/log/common/log.js';
 import { ChatMessageRole, LanguageModelsService, IChatMessage, IChatResponsePart, ILanguageModelChatMetadata } from '../../common/languageModels.js';
 import { IExtensionService, nullExtensionDescription } from '../../../../services/extensions/common/extensions.js';
-import { DEFAULT_MODEL_PICKER_CATEGORY } from '../../common/widget/input/modelPickerWidget.js';
 import { ExtensionIdentifier } from '../../../../../platform/extensions/common/extensions.js';
 import { TestStorageService } from '../../../../test/common/workbenchTestServices.js';
 import { Emitter, Event } from '../../../../../base/common/event.js';
@@ -70,7 +69,6 @@ suite('LanguageModels', function () {
 						vendor: 'test-vendor',
 						family: 'test-family',
 						version: 'test-version',
-						modelPickerCategory: undefined,
 						id: 'test-id-1',
 						maxInputTokens: 100,
 						maxOutputTokens: 100,
@@ -82,7 +80,6 @@ suite('LanguageModels', function () {
 						vendor: 'test-vendor',
 						family: 'test2-family',
 						version: 'test2-version',
-						modelPickerCategory: undefined,
 						id: 'test-id-12',
 						maxInputTokens: 100,
 						maxOutputTokens: 100,
@@ -149,7 +146,6 @@ suite('LanguageModels', function () {
 						id: 'actual-lm',
 						maxInputTokens: 100,
 						maxOutputTokens: 100,
-						modelPickerCategory: DEFAULT_MODEL_PICKER_CATEGORY,
 						isDefaultForLocation: {}
 					} satisfies ILanguageModelChatMetadata
 				];
@@ -358,7 +354,6 @@ suite('LanguageModels - Model Change Events', function () {
 						id: 'model1',
 						maxInputTokens: 100,
 						maxOutputTokens: 100,
-						modelPickerCategory: undefined,
 						isDefaultForLocation: {}
 					} satisfies ILanguageModelChatMetadata,
 					identifier: 'test-vendor/model1'
@@ -386,7 +381,6 @@ suite('LanguageModels - Model Change Events', function () {
 				id: 'model1',
 				maxInputTokens: 100,
 				maxOutputTokens: 100,
-				modelPickerCategory: undefined,
 				isDefaultForLocation: {}
 			} satisfies ILanguageModelChatMetadata,
 			identifier: 'test-vendor/model1'
@@ -430,7 +424,6 @@ suite('LanguageModels - Model Change Events', function () {
 				id: 'model1',
 				maxInputTokens: 100,
 				maxOutputTokens: 100,
-				modelPickerCategory: undefined,
 				isDefaultForLocation: {}
 			} satisfies ILanguageModelChatMetadata,
 			identifier: 'test-vendor/model1'
@@ -484,7 +477,6 @@ suite('LanguageModels - Model Change Events', function () {
 				id: 'model1',
 				maxInputTokens: 100,
 				maxOutputTokens: 100,
-				modelPickerCategory: undefined,
 				isDefaultForLocation: {}
 			} satisfies ILanguageModelChatMetadata,
 			identifier: 'test-vendor/model1'
@@ -531,7 +523,6 @@ suite('LanguageModels - Model Change Events', function () {
 				id: 'model1',
 				maxInputTokens: 100,
 				maxOutputTokens: 100,
-				modelPickerCategory: undefined,
 				isDefaultForLocation: {}
 			} satisfies ILanguageModelChatMetadata,
 			identifier: 'test-vendor/model1'
@@ -571,7 +562,6 @@ suite('LanguageModels - Model Change Events', function () {
 					id: 'model2',
 					maxInputTokens: 100,
 					maxOutputTokens: 100,
-					modelPickerCategory: undefined,
 					isDefaultForLocation: {}
 				} satisfies ILanguageModelChatMetadata,
 				identifier: 'test-vendor/model2'
@@ -602,7 +592,6 @@ suite('LanguageModels - Model Change Events', function () {
 							id: 'model1',
 							maxInputTokens: 100,
 							maxOutputTokens: 100,
-							modelPickerCategory: undefined,
 							isDefaultForLocation: {}
 						} satisfies ILanguageModelChatMetadata,
 						identifier: 'test-vendor/model1'
@@ -619,7 +608,6 @@ suite('LanguageModels - Model Change Events', function () {
 							id: 'model2',
 							maxInputTokens: 200,
 							maxOutputTokens: 200,
-							modelPickerCategory: undefined,
 							isDefaultForLocation: {}
 						} satisfies ILanguageModelChatMetadata,
 						identifier: 'test-vendor/model2'
@@ -813,7 +801,6 @@ suite('LanguageModels - Per-Model Configuration', function () {
 							id: 'model-a',
 							maxInputTokens: 100,
 							maxOutputTokens: 100,
-							modelPickerCategory: DEFAULT_MODEL_PICKER_CATEGORY,
 							isDefaultForLocation: {},
 							configurationSchema: {
 								type: 'object',
@@ -835,7 +822,6 @@ suite('LanguageModels - Per-Model Configuration', function () {
 							id: 'model-b',
 							maxInputTokens: 100,
 							maxOutputTokens: 100,
-							modelPickerCategory: DEFAULT_MODEL_PICKER_CATEGORY,
 							isDefaultForLocation: {}
 						} satisfies ILanguageModelChatMetadata,
 						identifier: 'config-vendor/default/model-b'
@@ -971,7 +957,6 @@ suite('LanguageModels - Provider Group Detail Fallback', function () {
 						id: 'shared-model',
 						maxInputTokens: 100,
 						maxOutputTokens: 100,
-						modelPickerCategory: DEFAULT_MODEL_PICKER_CATEGORY,
 						isDefaultForLocation: {}
 					} satisfies ILanguageModelChatMetadata,
 					identifier: `multi-vendor/${options.group}/shared-model`
@@ -1036,7 +1021,6 @@ suite('LanguageModels - Provider Group Detail Fallback', function () {
 						id: 'solo-model',
 						maxInputTokens: 100,
 						maxOutputTokens: 100,
-						modelPickerCategory: DEFAULT_MODEL_PICKER_CATEGORY,
 						isDefaultForLocation: {}
 					} satisfies ILanguageModelChatMetadata,
 					identifier: `single-vendor/${options.group}/solo-model`
@@ -1103,7 +1087,6 @@ suite('LanguageModels - Provider Group Detail Fallback', function () {
 						detail: `Detailed (${options.group})`,
 						maxInputTokens: 100,
 						maxOutputTokens: 100,
-						modelPickerCategory: DEFAULT_MODEL_PICKER_CATEGORY,
 						isDefaultForLocation: {}
 					} satisfies ILanguageModelChatMetadata,
 					identifier: `detail-vendor/${options.group}/detailed-model`
diff --git a/src/vs/workbench/contrib/chat/test/common/tools/builtinTools/runSubagentTool.test.ts b/src/vs/workbench/contrib/chat/test/common/tools/builtinTools/runSubagentTool.test.ts
index 792edcd2c184a..2c7e4a8787155 100644
--- a/src/vs/workbench/contrib/chat/test/common/tools/builtinTools/runSubagentTool.test.ts
+++ b/src/vs/workbench/contrib/chat/test/common/tools/builtinTools/runSubagentTool.test.ts
@@ -340,7 +340,6 @@ suite('RunSubagentTool', () => {
 				maxInputTokens: 128000,
 				maxOutputTokens: 8192,
 				isDefaultForLocation: {},
-				modelPickerCategory: undefined,
 				multiplierNumeric,
 				capabilities: { toolCalling: true },
 			};
@@ -616,7 +615,6 @@ suite('RunSubagentTool', () => {
 				maxInputTokens: 128000,
 				maxOutputTokens: 8192,
 				isDefaultForLocation: {},
-				modelPickerCategory: undefined,
 				multiplierNumeric,
 				capabilities: { toolCalling: true },
 			};
diff --git a/src/vscode-dts/vscode.proposed.chatProvider.d.ts b/src/vscode-dts/vscode.proposed.chatProvider.d.ts
index 1e73a4172b74f..a3c29ae139e5c 100644
--- a/src/vscode-dts/vscode.proposed.chatProvider.d.ts
+++ b/src/vscode-dts/vscode.proposed.chatProvider.d.ts
@@ -59,15 +59,6 @@ declare module 'vscode' {
 		 */
 		readonly isUserSelectable?: boolean;
 
-		/**
-		 * Optional category to group models by in the model picker.
-		 * The lower the order, the higher the category appears in the list.
-		 * Has no effect if `isUserSelectable` is `false`.
-		 *
-		 * WONT BE FINALIZED
-		 */
-		readonly category?: { label: string; order: number };
-
 		readonly statusIcon?: ThemeIcon;
 
 		/**

From 9df8712e1d8f79b980efcc01a731504464b1db63 Mon Sep 17 00:00:00 2001
From: Raymond Zhao <7199958+rzhao271@users.noreply.github.com>
Date: Wed, 13 May 2026 11:20:31 -0700
Subject: [PATCH 27/27] chore: run npm audit fix (#316150)

---
 build/rspack/package-lock.json       |  6 +++---
 extensions/copilot/package-lock.json |  2 +-
 extensions/copilot/package.json      |  2 +-
 package-lock.json                    | 12 ++++++------
 4 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/build/rspack/package-lock.json b/build/rspack/package-lock.json
index 1fdf97f60eb47..6ce456c7a10a6 100644
--- a/build/rspack/package-lock.json
+++ b/build/rspack/package-lock.json
@@ -2220,9 +2220,9 @@
       "license": "MIT"
     },
     "node_modules/fast-uri": {
-      "version": "3.1.0",
-      "resolved": "https://registry.npmjs.org/fast-uri/-/fast-uri-3.1.0.tgz",
-      "integrity": "sha512-iPeeDKJSWf4IEOasVVrknXpaBV0IApz/gp7S2bb7Z4Lljbl2MGJRqInZiUrQwV16cpzw/D3S5j5Julj/gT52AA==",
+      "version": "3.1.2",
+      "resolved": "https://registry.npmjs.org/fast-uri/-/fast-uri-3.1.2.tgz",
+      "integrity": "sha512-rVjf7ArG3LTk+FS6Yw81V1DLuZl1bRbNrev6Tmd/9RaroeeRRJhAt7jg/6YFxbvAQXUCavSoZhPPj6oOx+5KjQ==",
       "dev": true,
       "funding": [
         {
diff --git a/extensions/copilot/package-lock.json b/extensions/copilot/package-lock.json
index 55fc005e0aab2..87782713621d6 100644
--- a/extensions/copilot/package-lock.json
+++ b/extensions/copilot/package-lock.json
@@ -13,7 +13,7 @@
 				"@anthropic-ai/claude-agent-sdk": "0.2.112",
 				"@anthropic-ai/sdk": "^0.82.0",
 				"@github/blackbird-external-ingest-utils": "^0.3.0",
-				"@github/copilot": "^1.0.39",
+				"@github/copilot": "1.0.39",
 				"@google/genai": "^1.22.0",
 				"@humanwhocodes/gitignore-to-minimatch": "1.0.2",
 				"@microsoft/tiktokenizer": "^1.0.10",
diff --git a/extensions/copilot/package.json b/extensions/copilot/package.json
index cb607b4be012c..3b2f912818c66 100644
--- a/extensions/copilot/package.json
+++ b/extensions/copilot/package.json
@@ -6707,7 +6707,7 @@
 		"@anthropic-ai/claude-agent-sdk": "0.2.112",
 		"@anthropic-ai/sdk": "^0.82.0",
 		"@github/blackbird-external-ingest-utils": "^0.3.0",
-		"@github/copilot": "^1.0.39",
+		"@github/copilot": "1.0.39",
 		"@google/genai": "^1.22.0",
 		"@humanwhocodes/gitignore-to-minimatch": "1.0.2",
 		"@microsoft/tiktokenizer": "^1.0.10",
diff --git a/package-lock.json b/package-lock.json
index 8d2dea8215a6c..59778f0b11223 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -8488,9 +8488,9 @@
       "dev": true
     },
     "node_modules/fast-uri": {
-      "version": "3.1.0",
-      "resolved": "https://registry.npmjs.org/fast-uri/-/fast-uri-3.1.0.tgz",
-      "integrity": "sha512-iPeeDKJSWf4IEOasVVrknXpaBV0IApz/gp7S2bb7Z4Lljbl2MGJRqInZiUrQwV16cpzw/D3S5j5Julj/gT52AA==",
+      "version": "3.1.2",
+      "resolved": "https://registry.npmjs.org/fast-uri/-/fast-uri-3.1.2.tgz",
+      "integrity": "sha512-rVjf7ArG3LTk+FS6Yw81V1DLuZl1bRbNrev6Tmd/9RaroeeRRJhAt7jg/6YFxbvAQXUCavSoZhPPj6oOx+5KjQ==",
       "dev": true,
       "funding": [
         {
@@ -11291,9 +11291,9 @@
       }
     },
     "node_modules/hono": {
-      "version": "4.12.14",
-      "resolved": "https://registry.npmjs.org/hono/-/hono-4.12.14.tgz",
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