diff --git a/.eslintplugin/vscode-dts-interface-naming.ts b/.eslintplugin/vscode-dts-interface-naming.ts
index d9ec4e8c34c..59112bcb29d 100644
--- a/.eslintplugin/vscode-dts-interface-naming.ts
+++ b/.eslintplugin/vscode-dts-interface-naming.ts
@@ -8,7 +8,7 @@ import { TSESTree } from '@typescript-eslint/experimental-utils';
 
 export = new class ApiInterfaceNaming implements eslint.Rule.RuleModule {
 
-	private static _nameRegExp = /I[A-Z]/;
+	private static _nameRegExp = /^I[A-Z]/;
 
 	readonly meta: eslint.Rule.RuleMetaData = {
 		messages: {
diff --git a/src/vs/workbench/api/browser/mainThreadDialogs.ts b/src/vs/workbench/api/browser/mainThreadDialogs.ts
index e9ca6d75502..3ac34ea6b7b 100644
--- a/src/vs/workbench/api/browser/mainThreadDialogs.ts
+++ b/src/vs/workbench/api/browser/mainThreadDialogs.ts
@@ -7,6 +7,7 @@ import { URI } from 'vs/base/common/uri';
 import { MainThreadDiaglogsShape, MainContext, MainThreadDialogOpenOptions, MainThreadDialogSaveOptions } from '../common/extHost.protocol';
 import { extHostNamedCustomer, IExtHostContext } from 'vs/workbench/services/extensions/common/extHostCustomers';
 import { IFileDialogService, IOpenDialogOptions, ISaveDialogOptions } from 'vs/platform/dialogs/common/dialogs';
+import { Schemas } from 'vs/base/common/network';
 
 @extHostNamedCustomer(MainContext.MainThreadDialogs)
 export class MainThreadDialogs implements MainThreadDiaglogsShape {
@@ -46,7 +47,7 @@ export class MainThreadDialogs implements MainThreadDiaglogsShape {
 			canSelectMany: options?.canSelectMany,
 			defaultUri: options?.defaultUri ? URI.revive(options.defaultUri) : undefined,
 			title: options?.title || undefined,
-			availableFileSystems: []
+			availableFileSystems: options?.allowUIResources ? [Schemas.vscodeRemote, Schemas.file] : []
 		};
 		if (options?.filters) {
 			result.filters = [];
diff --git a/src/vs/workbench/api/common/extHost.api.impl.ts b/src/vs/workbench/api/common/extHost.api.impl.ts
index c33c3e72bfe..27edca9fa34 100644
--- a/src/vs/workbench/api/common/extHost.api.impl.ts
+++ b/src/vs/workbench/api/common/extHost.api.impl.ts
@@ -679,7 +679,7 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 				return extHostQuickOpen.showInput(options, token);
 			},
 			showOpenDialog(options) {
-				return extHostDialogs.showOpenDialog(options);
+				return extHostDialogs.showOpenDialog(extension, options);
 			},
 			showSaveDialog(options) {
 				return extHostDialogs.showSaveDialog(options);
diff --git a/src/vs/workbench/api/common/extHost.protocol.ts b/src/vs/workbench/api/common/extHost.protocol.ts
index 32078f50af6..414c984240f 100644
--- a/src/vs/workbench/api/common/extHost.protocol.ts
+++ b/src/vs/workbench/api/common/extHost.protocol.ts
@@ -174,6 +174,7 @@ export interface MainThreadDialogOpenOptions {
 	canSelectMany?: boolean;
 	filters?: { [name: string]: string[] };
 	title?: string;
+	allowUIResources?: boolean;
 }
 
 export interface MainThreadDialogSaveOptions {
diff --git a/src/vs/workbench/api/common/extHostDialogs.ts b/src/vs/workbench/api/common/extHostDialogs.ts
index 69de2a3e7f8..c33cb0704dd 100644
--- a/src/vs/workbench/api/common/extHostDialogs.ts
+++ b/src/vs/workbench/api/common/extHostDialogs.ts
@@ -6,6 +6,8 @@
 import type * as vscode from 'vscode';
 import { URI } from 'vs/base/common/uri';
 import { MainContext, MainThreadDiaglogsShape, IMainContext } from 'vs/workbench/api/common/extHost.protocol';
+import { checkProposedApiEnabled } from 'vs/workbench/services/extensions/common/extensions';
+import { IRelaxedExtensionDescription } from 'vs/platform/extensions/common/extensions';
 
 export class ExtHostDialogs {
 
@@ -15,7 +17,10 @@ export class ExtHostDialogs {
 		this._proxy = mainContext.getProxy(MainContext.MainThreadDialogs);
 	}
 
-	showOpenDialog(options?: vscode.OpenDialogOptions): Promise<URI[] | undefined> {
+	showOpenDialog(extension: IRelaxedExtensionDescription, options?: vscode.OpenDialogOptions): Promise<URI[] | undefined> {
+		if (options?.allowUIResources) {
+			checkProposedApiEnabled(extension, 'showLocal');
+		}
 		return this._proxy.$showOpenDialog(options).then(filepaths => {
 			return filepaths ? filepaths.map(p => URI.revive(p)) : undefined;
 		});
diff --git a/src/vs/workbench/services/extensions/common/extensionsApiProposals.ts b/src/vs/workbench/services/extensions/common/extensionsApiProposals.ts
index 8468acd74d6..8929645d6dd 100644
--- a/src/vs/workbench/services/extensions/common/extensionsApiProposals.ts
+++ b/src/vs/workbench/services/extensions/common/extensionsApiProposals.ts
@@ -56,6 +56,7 @@ export const allApiProposals = Object.freeze({
 	scmActionButton: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.scmActionButton.d.ts',
 	scmSelectedProvider: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.scmSelectedProvider.d.ts',
 	scmValidation: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.scmValidation.d.ts',
+	showLocal: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.showLocal.d.ts',
 	tabInputTextMerge: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.tabInputTextMerge.d.ts',
 	taskPresentationGroup: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.taskPresentationGroup.d.ts',
 	telemetry: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.telemetry.d.ts',
diff --git a/src/vscode-dts/vscode.proposed.showLocal.d.ts b/src/vscode-dts/vscode.proposed.showLocal.d.ts
new file mode 100644
index 00000000000..9a9294f596b
--- /dev/null
+++ b/src/vscode-dts/vscode.proposed.showLocal.d.ts
@@ -0,0 +1,19 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+// https://github.com/microsoft/vscode/issues/131138
+
+declare module 'vscode' {
+
+	export interface OpenDialogOptions {
+		/**
+		 * Controls whether the dialog allows users to select local files via the "Show Local" button.
+		 * Extensions that set this to `true` should check the scheme of the selected file.
+		 * Resources with the `file` scheme come from the same extension host as the extension.
+		 * Resources with the `vscode-local` scheme come from an extension host running in the same place as the UI.
+		 */
+		allowUIResources?: boolean;
+	}
+}