Set a read-only message from an extension (#185216)

* wip

* Allow extensions to provide a readonly message
Part of #166971

* Address feedback

* Further address feedback

* Fix some nits

* Add test

* Improve tests and respond to feedback

* Don't render editor.readOnlyMessage in the settings UI

* No need to validate the IMarkdownString

---------

Co-authored-by: Benjamin Pasero <benjamin.pasero@microsoft.com>
Co-authored-by: Alex Dima <alexdima@microsoft.com>

extensions/vscode-api-tests/package.json

@@ -26,6 +26,7 @@
     "notebookMime",
     "portsAttributes",
     "quickPickSortByLabel",
+    "readonlyMessage",
     "resolvers",
     "saveEditor",
     "scmActionButton",

extensions/vscode-api-tests/src/singlefolder-tests/readonlyFileSystem.test.ts

@@ -0,0 +1,63 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as assert from 'assert';
+import * as vscode from 'vscode';
+import { TestFS } from '../memfs';
+import { assertNoRpc, closeAllEditors } from '../utils';
+
+suite('vscode API - file system', () => {
+
+	teardown(async function () {
+		assertNoRpc();
+		await closeAllEditors();
+	});
+
+	test('readonly file system - boolean', async function () {
+		const fs = new TestFS('this-fs', false);
+		const reg = vscode.workspace.registerFileSystemProvider(fs.scheme, fs, { isReadonly: true });
+		let error: any | undefined;
+		try {
+			await vscode.workspace.fs.writeFile(vscode.Uri.parse('this-fs:/foo.txt'), Buffer.from('Hello World'));
+		} catch (e) {
+			error = e;
+		}
+		assert.strictEqual(vscode.workspace.fs.isWritableFileSystem('this-fs'), false);
+		assert.strictEqual(error instanceof vscode.FileSystemError, true);
+		const fileError: vscode.FileSystemError = error;
+		assert.strictEqual(fileError.code, 'NoPermissions');
+		reg.dispose();
+	});
+
+	test('readonly file system - markdown', async function () {
+		const fs = new TestFS('this-fs', false);
+		const reg = vscode.workspace.registerFileSystemProvider(fs.scheme, fs, { isReadonly: new vscode.MarkdownString('This file is readonly.') });
+		let error: any | undefined;
+		try {
+			await vscode.workspace.fs.writeFile(vscode.Uri.parse('this-fs:/foo.txt'), Buffer.from('Hello World'));
+		} catch (e) {
+			error = e;
+		}
+		assert.strictEqual(vscode.workspace.fs.isWritableFileSystem('this-fs'), false);
+		assert.strictEqual(error instanceof vscode.FileSystemError, true);
+		const fileError: vscode.FileSystemError = error;
+		assert.strictEqual(fileError.code, 'NoPermissions');
+		reg.dispose();
+	});
+
+	test('writeable file system', async function () {
+		const fs = new TestFS('this-fs', false);
+		const reg = vscode.workspace.registerFileSystemProvider(fs.scheme, fs);
+		let error: any | undefined;
+		try {
+			await vscode.workspace.fs.writeFile(vscode.Uri.parse('this-fs:/foo.txt'), Buffer.from('Hello World'));
+		} catch (e) {
+			error = e;
+		}
+		assert.strictEqual(vscode.workspace.fs.isWritableFileSystem('this-fs'), true);
+		assert.strictEqual(error, undefined);
+		reg.dispose();
+	});
+});

src/vs/editor/common/config/editorOptions.ts

@@ -16,6 +16,7 @@ import * as arrays from 'vs/base/common/arrays';
 import * as objects from 'vs/base/common/objects';
 import { EDITOR_MODEL_DEFAULTS } from 'vs/editor/common/core/textModelDefaults';
 import { IDocumentDiffProvider } from 'vs/editor/common/diff/documentDiffProvider';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 //#region typed options
 
@@ -151,6 +152,10 @@ export interface IEditorOptions {
 	 * Defaults to false.
 	 */
 	readOnly?: boolean;
+	/**
+	 * The message to display when the editor is readonly.
+	 */
+	readOnlyMessage?: IMarkdownString;
 	/**
 	 * Should the textarea used for input use the DOM `readonly` attribute.
 	 * Defaults to false.
@@ -3459,6 +3464,30 @@ class EditorRulers extends BaseEditorOption<EditorOption.rulers, (number | IRule
 
 //#endregion
 
+//#region readonly
+
+/**
+ * Configuration options for readonly message
+ */
+class ReadonlyMessage extends BaseEditorOption<EditorOption.readOnlyMessage, IMarkdownString | undefined, IMarkdownString | undefined> {
+	constructor() {
+		const defaults = undefined;
+
+		super(
+			EditorOption.readOnlyMessage, 'readOnlyMessage', defaults
+		);
+	}
+
+	public validate(_input: any): IMarkdownString | undefined {
+		if (!_input || typeof _input !== 'object') {
+			return this.defaultValue;
+		}
+		return _input as IMarkdownString;
+	}
+}
+
+//#endregion
+
 //#region scrollbar
 
 /**
@@ -5024,6 +5053,7 @@ export const enum EditorOption {
 	quickSuggestions,
 	quickSuggestionsDelay,
 	readOnly,
+	readOnlyMessage,
 	renameOnType,
 	renderControlCharacters,
 	renderFinalNewline,
@@ -5530,6 +5560,7 @@ export const EditorOptions = {
 	readOnly: register(new EditorBooleanOption(
 		EditorOption.readOnly, 'readOnly', false,
 	)),
+	readOnlyMessage: register(new ReadonlyMessage()),
 	renameOnType: register(new EditorBooleanOption(
 		EditorOption.renameOnType, 'renameOnType', false,
 		{ description: nls.localize('renameOnType', "Controls whether the editor auto renames on type."), markdownDeprecationMessage: nls.localize('renameOnTypeDeprecate', "Deprecated, use `editor.linkedEditing` instead.") }

src/vs/editor/common/services/resolverService.ts

@@ -3,6 +3,7 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 import { IDisposable, IReference } from 'vs/base/common/lifecycle';
 import { URI } from 'vs/base/common/uri';
 import { ITextModel, ITextSnapshot } from 'vs/editor/common/model';
@@ -55,7 +56,7 @@ export interface ITextEditorModel extends IEditorModel {
 	/**
 	 * Signals if this model is readonly or not.
 	 */
-	isReadonly(): boolean;
+	isReadonly(): boolean | IMarkdownString;
 
 	/**
 	 * The language id of the text model if known.

src/vs/editor/common/standalone/standaloneEnums.ts

@@ -262,61 +262,62 @@ export enum EditorOption {
 	quickSuggestions = 86,
 	quickSuggestionsDelay = 87,
 	readOnly = 88,
-	renameOnType = 89,
-	renderControlCharacters = 90,
-	renderFinalNewline = 91,
-	renderLineHighlight = 92,
-	renderLineHighlightOnlyWhenFocus = 93,
-	renderValidationDecorations = 94,
-	renderWhitespace = 95,
-	revealHorizontalRightPadding = 96,
-	roundedSelection = 97,
-	rulers = 98,
-	scrollbar = 99,
-	scrollBeyondLastColumn = 100,
-	scrollBeyondLastLine = 101,
-	scrollPredominantAxis = 102,
-	selectionClipboard = 103,
-	selectionHighlight = 104,
-	selectOnLineNumbers = 105,
-	showFoldingControls = 106,
-	showUnused = 107,
-	snippetSuggestions = 108,
-	smartSelect = 109,
-	smoothScrolling = 110,
-	stickyScroll = 111,
-	stickyTabStops = 112,
-	stopRenderingLineAfter = 113,
-	suggest = 114,
-	suggestFontSize = 115,
-	suggestLineHeight = 116,
-	suggestOnTriggerCharacters = 117,
-	suggestSelection = 118,
-	tabCompletion = 119,
-	tabIndex = 120,
-	unicodeHighlighting = 121,
-	unusualLineTerminators = 122,
-	useShadowDOM = 123,
-	useTabStops = 124,
-	wordBreak = 125,
-	wordSeparators = 126,
-	wordWrap = 127,
-	wordWrapBreakAfterCharacters = 128,
-	wordWrapBreakBeforeCharacters = 129,
-	wordWrapColumn = 130,
-	wordWrapOverride1 = 131,
-	wordWrapOverride2 = 132,
-	wrappingIndent = 133,
-	wrappingStrategy = 134,
-	showDeprecated = 135,
-	inlayHints = 136,
-	editorClassName = 137,
-	pixelRatio = 138,
-	tabFocusMode = 139,
-	layoutInfo = 140,
-	wrappingInfo = 141,
-	defaultColorDecorators = 142,
-	colorDecoratorsActivatedOn = 143
+	readOnlyMessage = 89,
+	renameOnType = 90,
+	renderControlCharacters = 91,
+	renderFinalNewline = 92,
+	renderLineHighlight = 93,
+	renderLineHighlightOnlyWhenFocus = 94,
+	renderValidationDecorations = 95,
+	renderWhitespace = 96,
+	revealHorizontalRightPadding = 97,
+	roundedSelection = 98,
+	rulers = 99,
+	scrollbar = 100,
+	scrollBeyondLastColumn = 101,
+	scrollBeyondLastLine = 102,
+	scrollPredominantAxis = 103,
+	selectionClipboard = 104,
+	selectionHighlight = 105,
+	selectOnLineNumbers = 106,
+	showFoldingControls = 107,
+	showUnused = 108,
+	snippetSuggestions = 109,
+	smartSelect = 110,
+	smoothScrolling = 111,
+	stickyScroll = 112,
+	stickyTabStops = 113,
+	stopRenderingLineAfter = 114,
+	suggest = 115,
+	suggestFontSize = 116,
+	suggestLineHeight = 117,
+	suggestOnTriggerCharacters = 118,
+	suggestSelection = 119,
+	tabCompletion = 120,
+	tabIndex = 121,
+	unicodeHighlighting = 122,
+	unusualLineTerminators = 123,
+	useShadowDOM = 124,
+	useTabStops = 125,
+	wordBreak = 126,
+	wordSeparators = 127,
+	wordWrap = 128,
+	wordWrapBreakAfterCharacters = 129,
+	wordWrapBreakBeforeCharacters = 130,
+	wordWrapColumn = 131,
+	wordWrapOverride1 = 132,
+	wordWrapOverride2 = 133,
+	wrappingIndent = 134,
+	wrappingStrategy = 135,
+	showDeprecated = 136,
+	inlayHints = 137,
+	editorClassName = 138,
+	pixelRatio = 139,
+	tabFocusMode = 140,
+	layoutInfo = 141,
+	wrappingInfo = 142,
+	defaultColorDecorators = 143,
+	colorDecoratorsActivatedOn = 144
 }
 
 /**
@@ -920,4 +921,4 @@ export enum WrappingIndent {
 	 * DeepIndent => wrapped lines get +2 indentation toward the parent.
 	 */
 	DeepIndent = 3
-}
+}

src/vs/editor/contrib/message/browser/messageController.css

@@ -37,6 +37,15 @@
 	border: 1px solid var(--vscode-inputValidation-infoBorder);
 }
 
+.monaco-editor .monaco-editor-overlaymessage .message p {
+	margin-block: 0px;
+}
+
+.monaco-editor .monaco-editor-overlaymessage .message a {
+	font-weight: bold;
+	color: var(--vscode-inputValidation-infoForeground);
+}
+
 .monaco-editor.hc-black .monaco-editor-overlaymessage .message,
 .monaco-editor.hc-light .monaco-editor-overlaymessage .message {
 	border-width: 2px;

src/vs/editor/contrib/message/browser/messageController.ts

@@ -3,8 +3,10 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
+import { renderMarkdown } from 'vs/base/browser/markdownRenderer';
 import { alert } from 'vs/base/browser/ui/aria/aria';
 import { TimeoutTimer } from 'vs/base/common/async';
+import { IMarkdownString, isMarkdownString } from 'vs/base/common/htmlContent';
 import { KeyCode } from 'vs/base/common/keyCodes';
 import { DisposableStore, IDisposable, MutableDisposable } from 'vs/base/common/lifecycle';
 import 'vs/css!./messageController';
@@ -14,9 +16,12 @@ import { IPosition } from 'vs/editor/common/core/position';
 import { Range } from 'vs/editor/common/core/range';
 import { IEditorContribution, ScrollType } from 'vs/editor/common/editorCommon';
 import { PositionAffinity } from 'vs/editor/common/model';
+import { openLinkFromMarkdown } from 'vs/editor/contrib/markdownRenderer/browser/markdownRenderer';
 import * as nls from 'vs/nls';
 import { IContextKey, IContextKeyService, RawContextKey } from 'vs/platform/contextkey/common/contextkey';
 import { KeybindingWeight } from 'vs/platform/keybinding/common/keybindingsRegistry';
+import { IOpenerService } from 'vs/platform/opener/common/opener';
+import * as dom from 'vs/base/browser/dom';
 
 export class MessageController implements IEditorContribution {
 
@@ -32,10 +37,13 @@ export class MessageController implements IEditorContribution {
 	private readonly _visible: IContextKey<boolean>;
 	private readonly _messageWidget = new MutableDisposable<MessageWidget>();
 	private readonly _messageListeners = new DisposableStore();
+	private _message: { element: HTMLElement; dispose: () => void } | undefined;
+	private _focus: boolean = false;
 
 	constructor(
 		editor: ICodeEditor,
-		@IContextKeyService contextKeyService: IContextKeyService
+		@IContextKeyService contextKeyService: IContextKeyService,
+		@IOpenerService private readonly _openerService: IOpenerService
 	) {
 
 		this._editor = editor;
@@ -43,6 +51,7 @@ export class MessageController implements IEditorContribution {
 	}
 
 	dispose(): void {
+		this._message?.dispose();
 		this._messageListeners.dispose();
 		this._messageWidget.dispose();
 		this._visible.reset();
@@ -52,20 +61,33 @@ export class MessageController implements IEditorContribution {
 		return this._visible.get();
 	}
 
-	showMessage(message: string, position: IPosition): void {
+	showMessage(message: IMarkdownString | string, position: IPosition): void {
 
-		alert(message);
+		alert(isMarkdownString(message) ? message.value : message);
 
 		this._visible.set(true);
 		this._messageWidget.clear();
 		this._messageListeners.clear();
-		this._messageWidget.value = new MessageWidget(this._editor, position, message);
+		this._message = isMarkdownString(message) ? renderMarkdown(message, {
+			actionHandler: {
+				callback: (url) => openLinkFromMarkdown(this._openerService, url, isMarkdownString(message) ? message.isTrusted : undefined),
+				disposables: this._messageListeners
+			},
+		}) : undefined;
+		this._messageWidget.value = new MessageWidget(this._editor, position, typeof message === 'string' ? message : this._message!.element);
 
 		// close on blur, cursor, model change, dispose
-		this._messageListeners.add(this._editor.onDidBlurEditorText(() => this.closeMessage()));
+		this._messageListeners.add(this._editor.onDidBlurEditorText(() => {
+			if (!this._focus) {
+				this.closeMessage();
+			}
+		}
+		));
 		this._messageListeners.add(this._editor.onDidChangeCursorPosition(() => this.closeMessage()));
 		this._messageListeners.add(this._editor.onDidDispose(() => this.closeMessage()));
 		this._messageListeners.add(this._editor.onDidChangeModel(() => this.closeMessage()));
+		this._messageListeners.add(dom.addDisposableListener(this._messageWidget.value.getDomNode(), dom.EventType.MOUSE_ENTER, () => this._focus = true, true));
+		this._messageListeners.add(dom.addDisposableListener(this._messageWidget.value.getDomNode(), dom.EventType.MOUSE_LEAVE, () => this._focus = false, true));
 
 		// 3sec
 		this._messageListeners.add(new TimeoutTimer(() => this.closeMessage(), 3000));
@@ -132,7 +154,7 @@ class MessageWidget implements IContentWidget {
 		return { dispose };
 	}
 
-	constructor(editor: ICodeEditor, { lineNumber, column }: IPosition, text: string) {
+	constructor(editor: ICodeEditor, { lineNumber, column }: IPosition, text: HTMLElement | string) {
 
 		this._editor = editor;
 		this._editor.revealLinesInCenterIfOutsideViewport(lineNumber, lineNumber, ScrollType.Smooth);
@@ -147,8 +169,13 @@ class MessageWidget implements IContentWidget {
 		this._domNode.appendChild(anchorTop);
 
 		const message = document.createElement('div');
-		message.classList.add('message');
-		message.textContent = text;
+		if (typeof text === 'string') {
+			message.classList.add('message');
+			message.textContent = text;
+		} else {
+			text.classList.add('message');
+			message.appendChild(text);
+		}
 		this._domNode.appendChild(message);
 
 		const anchorBottom = document.createElement('div');

src/vs/editor/contrib/readOnlyMessage/browser/contribution.ts

@@ -3,9 +3,11 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
+import { MarkdownString } from 'vs/base/common/htmlContent';
 import { Disposable } from 'vs/base/common/lifecycle';
 import { ICodeEditor } from 'vs/editor/browser/editorBrowser';
 import { EditorContributionInstantiation, registerEditorContribution } from 'vs/editor/browser/editorExtensions';
+import { EditorOption } from 'vs/editor/common/config/editorOptions';
 import { IEditorContribution } from 'vs/editor/common/editorCommon';
 import { MessageController } from 'vs/editor/contrib/message/browser/messageController';
 import * as nls from 'vs/nls';
@@ -24,11 +26,16 @@ export class ReadOnlyMessageController extends Disposable implements IEditorCont
 	private _onDidAttemptReadOnlyEdit(): void {
 		const messageController = MessageController.get(this.editor);
 		if (messageController && this.editor.hasModel()) {
-			if (this.editor.isSimpleWidget) {
-				messageController.showMessage(nls.localize('editor.simple.readonly', "Cannot edit in read-only input"), this.editor.getPosition());
-			} else {
-				messageController.showMessage(nls.localize('editor.readonly', "Cannot edit in read-only editor"), this.editor.getPosition());
+			let message = this.editor.getOptions().get(EditorOption.readOnlyMessage);
+			if (!message) {
+				if (this.editor.isSimpleWidget) {
+					message = new MarkdownString(nls.localize('editor.simple.readonly', "Cannot edit in read-only input"));
+				} else {
+					message = new MarkdownString(nls.localize('editor.readonly', "Cannot edit in read-only editor"));
+				}
 			}
+
+			messageController.showMessage(message, this.editor.getPosition());
 		}
 	}
 }

src/vs/monaco.d.ts

@@ -3309,6 +3309,10 @@ declare namespace monaco.editor {
 		 * Defaults to false.
 		 */
 		readOnly?: boolean;
+		/**
+		 * The message to display when the editor is readonly.
+		 */
+		readOnlyMessage?: IMarkdownString;
 		/**
 		 * Should the textarea used for input use the DOM `readonly` attribute.
 		 * Defaults to false.
@@ -4934,61 +4938,62 @@ declare namespace monaco.editor {
 		quickSuggestions = 86,
 		quickSuggestionsDelay = 87,
 		readOnly = 88,
-		renameOnType = 89,
-		renderControlCharacters = 90,
-		renderFinalNewline = 91,
-		renderLineHighlight = 92,
-		renderLineHighlightOnlyWhenFocus = 93,
-		renderValidationDecorations = 94,
-		renderWhitespace = 95,
-		revealHorizontalRightPadding = 96,
-		roundedSelection = 97,
-		rulers = 98,
-		scrollbar = 99,
-		scrollBeyondLastColumn = 100,
-		scrollBeyondLastLine = 101,
-		scrollPredominantAxis = 102,
-		selectionClipboard = 103,
-		selectionHighlight = 104,
-		selectOnLineNumbers = 105,
-		showFoldingControls = 106,
-		showUnused = 107,
-		snippetSuggestions = 108,
-		smartSelect = 109,
-		smoothScrolling = 110,
-		stickyScroll = 111,
-		stickyTabStops = 112,
-		stopRenderingLineAfter = 113,
-		suggest = 114,
-		suggestFontSize = 115,
-		suggestLineHeight = 116,
-		suggestOnTriggerCharacters = 117,
-		suggestSelection = 118,
-		tabCompletion = 119,
-		tabIndex = 120,
-		unicodeHighlighting = 121,
-		unusualLineTerminators = 122,
-		useShadowDOM = 123,
-		useTabStops = 124,
-		wordBreak = 125,
-		wordSeparators = 126,
-		wordWrap = 127,
-		wordWrapBreakAfterCharacters = 128,
-		wordWrapBreakBeforeCharacters = 129,
-		wordWrapColumn = 130,
-		wordWrapOverride1 = 131,
-		wordWrapOverride2 = 132,
-		wrappingIndent = 133,
-		wrappingStrategy = 134,
-		showDeprecated = 135,
-		inlayHints = 136,
-		editorClassName = 137,
-		pixelRatio = 138,
-		tabFocusMode = 139,
-		layoutInfo = 140,
-		wrappingInfo = 141,
-		defaultColorDecorators = 142,
-		colorDecoratorsActivatedOn = 143
+		readOnlyMessage = 89,
+		renameOnType = 90,
+		renderControlCharacters = 91,
+		renderFinalNewline = 92,
+		renderLineHighlight = 93,
+		renderLineHighlightOnlyWhenFocus = 94,
+		renderValidationDecorations = 95,
+		renderWhitespace = 96,
+		revealHorizontalRightPadding = 97,
+		roundedSelection = 98,
+		rulers = 99,
+		scrollbar = 100,
+		scrollBeyondLastColumn = 101,
+		scrollBeyondLastLine = 102,
+		scrollPredominantAxis = 103,
+		selectionClipboard = 104,
+		selectionHighlight = 105,
+		selectOnLineNumbers = 106,
+		showFoldingControls = 107,
+		showUnused = 108,
+		snippetSuggestions = 109,
+		smartSelect = 110,
+		smoothScrolling = 111,
+		stickyScroll = 112,
+		stickyTabStops = 113,
+		stopRenderingLineAfter = 114,
+		suggest = 115,
+		suggestFontSize = 116,
+		suggestLineHeight = 117,
+		suggestOnTriggerCharacters = 118,
+		suggestSelection = 119,
+		tabCompletion = 120,
+		tabIndex = 121,
+		unicodeHighlighting = 122,
+		unusualLineTerminators = 123,
+		useShadowDOM = 124,
+		useTabStops = 125,
+		wordBreak = 126,
+		wordSeparators = 127,
+		wordWrap = 128,
+		wordWrapBreakAfterCharacters = 129,
+		wordWrapBreakBeforeCharacters = 130,
+		wordWrapColumn = 131,
+		wordWrapOverride1 = 132,
+		wordWrapOverride2 = 133,
+		wrappingIndent = 134,
+		wrappingStrategy = 135,
+		showDeprecated = 136,
+		inlayHints = 137,
+		editorClassName = 138,
+		pixelRatio = 139,
+		tabFocusMode = 140,
+		layoutInfo = 141,
+		wrappingInfo = 142,
+		defaultColorDecorators = 143,
+		colorDecoratorsActivatedOn = 144
 	}
 
 	export const EditorOptions: {
@@ -5083,6 +5088,7 @@ declare namespace monaco.editor {
 		quickSuggestions: IEditorOption<EditorOption.quickSuggestions, InternalQuickSuggestionsOptions>;
 		quickSuggestionsDelay: IEditorOption<EditorOption.quickSuggestionsDelay, number>;
 		readOnly: IEditorOption<EditorOption.readOnly, boolean>;
+		readOnlyMessage: IEditorOption<EditorOption.readOnlyMessage, any>;
 		renameOnType: IEditorOption<EditorOption.renameOnType, boolean>;
 		renderControlCharacters: IEditorOption<EditorOption.renderControlCharacters, boolean>;
 		renderFinalNewline: IEditorOption<EditorOption.renderFinalNewline, 'on' | 'off' | 'dimmed'>;

src/vs/platform/files/common/files.ts

@@ -18,6 +18,7 @@ import { localize } from 'vs/nls';
 import { createDecorator } from 'vs/platform/instantiation/common/instantiation';
 import { isWeb } from 'vs/base/common/platform';
 import { Schemas } from 'vs/base/common/network';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 //#region file service & providers
 
@@ -583,6 +584,7 @@ export const enum FileSystemProviderCapabilities {
 export interface IFileSystemProvider {
 
 	readonly capabilities: FileSystemProviderCapabilities;
+	readonly readOnlyMessage?: IMarkdownString;
 	readonly onDidChangeCapabilities: Event<void>;
 
 	readonly onDidChangeFile: Event<readonly IFileChange[]>;

src/vs/workbench/api/browser/mainThreadFileSystem.ts

@@ -17,6 +17,7 @@ import { IWorkbenchFileService } from 'vs/workbench/services/files/common/files'
 import { normalizeWatcherPattern } from 'vs/platform/files/common/watcher';
 import { GLOBSTAR } from 'vs/base/common/glob';
 import { rtrim } from 'vs/base/common/strings';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 @extHostNamedCustomer(MainContext.MainThreadFileSystem)
 export class MainThreadFileSystem implements MainThreadFileSystemShape {
@@ -50,8 +51,8 @@ export class MainThreadFileSystem implements MainThreadFileSystemShape {
 		this._watches.dispose();
 	}
 
-	async $registerFileSystemProvider(handle: number, scheme: string, capabilities: FileSystemProviderCapabilities): Promise<void> {
-		this._fileProvider.set(handle, new RemoteFileSystemProvider(this._fileService, scheme, capabilities, handle, this._proxy));
+	async $registerFileSystemProvider(handle: number, scheme: string, capabilities: FileSystemProviderCapabilities, readonlyMessage?: IMarkdownString): Promise<void> {
+		this._fileProvider.set(handle, new RemoteFileSystemProvider(this._fileService, scheme, capabilities, readonlyMessage, handle, this._proxy));
 	}
 
 	$unregisterProvider(handle: number): void {
@@ -273,6 +274,7 @@ class RemoteFileSystemProvider implements IFileSystemProviderWithFileReadWriteCa
 		fileService: IFileService,
 		scheme: string,
 		capabilities: FileSystemProviderCapabilities,
+		public readonly readOnlyMessage: IMarkdownString | undefined,
 		private readonly _handle: number,
 		private readonly _proxy: ExtHostFileSystemShape
 	) {

src/vs/workbench/api/common/extHost.protocol.ts

@@ -1236,7 +1236,7 @@ export interface IFileChangeDto {
 }
 
 export interface MainThreadFileSystemShape extends IDisposable {
-	$registerFileSystemProvider(handle: number, scheme: string, capabilities: files.FileSystemProviderCapabilities): Promise<void>;
+	$registerFileSystemProvider(handle: number, scheme: string, capabilities: files.FileSystemProviderCapabilities, readonlyMessage?: IMarkdownString): Promise<void>;
 	$unregisterProvider(handle: number): void;
 	$onFileSystemChange(handle: number, resource: IFileChangeDto[]): void;
 

src/vs/workbench/api/common/extHostFileSystem.ts

@@ -17,6 +17,7 @@ import { CharCode } from 'vs/base/common/charCode';
 import { VSBuffer } from 'vs/base/common/buffer';
 import { IExtensionDescription } from 'vs/platform/extensions/common/extensions';
 import { checkProposedApiEnabled } from 'vs/workbench/services/extensions/common/extensions';
+import { IMarkdownString, isMarkdownString } from 'vs/base/common/htmlContent';
 
 class FsLinkProvider {
 
@@ -128,7 +129,7 @@ export class ExtHostFileSystem implements ExtHostFileSystemShape {
 		this._linkProviderRegistration?.dispose();
 	}
 
-	registerFileSystemProvider(extension: IExtensionDescription, scheme: string, provider: vscode.FileSystemProvider, options: { isCaseSensitive?: boolean; isReadonly?: boolean } = {}) {
+	registerFileSystemProvider(extension: IExtensionDescription, scheme: string, provider: vscode.FileSystemProvider, options: { isCaseSensitive?: boolean; isReadonly?: boolean | vscode.MarkdownString } = {}) {
 
 		// validate the given provider is complete
 		ExtHostFileSystem._validateFileSystemProvider(provider);
@@ -164,7 +165,20 @@ export class ExtHostFileSystem implements ExtHostFileSystemShape {
 			capabilities += files.FileSystemProviderCapabilities.FileOpenReadWriteClose;
 		}
 
-		this._proxy.$registerFileSystemProvider(handle, scheme, capabilities).catch(err => {
+		let readOnlyMessage: IMarkdownString | undefined;
+		if (options.isReadonly && isMarkdownString(options.isReadonly)) {
+			checkProposedApiEnabled(extension, 'readonlyMessage');
+			readOnlyMessage = {
+				value: options.isReadonly.value,
+				isTrusted: options.isReadonly.isTrusted,
+				supportThemeIcons: options.isReadonly.supportThemeIcons,
+				supportHtml: options.isReadonly.supportHtml,
+				baseUri: options.isReadonly.baseUri,
+				uris: options.isReadonly.uris
+			};
+		}
+
+		this._proxy.$registerFileSystemProvider(handle, scheme, capabilities, readOnlyMessage).catch(err => {
 			console.error(`FAILED to register filesystem provider of ${extension.identifier.value}-extension for the scheme ${scheme}`);
 			console.error(err);
 		});

src/vs/workbench/browser/parts/editor/editorWithViewState.ts

@@ -17,6 +17,7 @@ import { IEditorService } from 'vs/workbench/services/editor/common/editorServic
 import { IExtUri } from 'vs/base/common/resources';
 import { IDisposable, MutableDisposable } from 'vs/base/common/lifecycle';
 import { EditorInput } from 'vs/workbench/common/editor/editorInput';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 /**
  * Base class of editors that want to store and restore view state.
@@ -53,6 +54,12 @@ export abstract class AbstractEditorWithViewState<T extends object> extends Edit
 		super.setEditorVisible(visible, group);
 	}
 
+	protected readonlyValues(isReadonly: boolean | IMarkdownString | undefined): { readOnly: boolean; readOnlyMessage: IMarkdownString | undefined } {
+		const readOnly = !!isReadonly;
+		const readOnlyMessage = typeof isReadonly !== 'boolean' ? isReadonly : undefined;
+		return { readOnly, readOnlyMessage };
+	}
+
 	private onWillCloseEditor(e: IEditorCloseEvent): void {
 		const editor = e.editor;
 		if (editor === this.input) {

src/vs/workbench/browser/parts/editor/textDiffEditor.ts

@@ -160,7 +160,7 @@ export class TextDiffEditor extends AbstractTextEditor<IDiffEditorViewState> imp
 			// a resolved model might have more specific information about being
 			// readonly or not that the input did not have.
 			control.updateOptions({
-				readOnly: resolvedDiffEditorModel.modifiedModel?.isReadonly(),
+				...this.readonlyValues(resolvedDiffEditorModel.modifiedModel?.isReadonly()),
 				originalEditable: !resolvedDiffEditorModel.originalModel?.isReadonly()
 			});
 

src/vs/workbench/browser/parts/editor/textEditor.ts

@@ -144,13 +144,11 @@ export abstract class AbstractTextEditor<T extends IEditorViewState> extends Abs
 	}
 
 	protected getConfigurationOverrides(): ICodeEditorOptions {
-		const readOnly = this.input?.hasCapability(EditorInputCapabilities.Readonly);
-
 		return {
 			overviewRulerLanes: 3,
 			lineNumbersMinChars: 3,
 			fixedOverflowWidgets: true,
-			readOnly,
+			...this.readonlyValues(this.input?.isReadonly()),
 			renderValidationDecorations: 'on' // render problems even in readonly editors (https://github.com/microsoft/vscode/issues/89057)
 		};
 	}

src/vs/workbench/browser/parts/editor/textResourceEditor.ts

@@ -92,7 +92,7 @@ export abstract class AbstractTextResourceEditor extends AbstractTextCodeEditor<
 		// was already asked for being readonly or not. The rationale is that
 		// a resolved model might have more specific information about being
 		// readonly or not that the input did not have.
-		control.updateOptions({ readOnly: resolvedModel.isReadonly() });
+		control.updateOptions(this.readonlyValues(resolvedModel.isReadonly()));
 	}
 
 	/**

src/vs/workbench/common/editor/editorInput.ts

@@ -10,6 +10,7 @@ import { firstOrDefault } from 'vs/base/common/arrays';
 import { EditorInputCapabilities, Verbosity, GroupIdentifier, ISaveOptions, IRevertOptions, IMoveResult, IEditorDescriptor, IEditorPane, IUntypedEditorInput, EditorResourceAccessor, AbstractEditorInput, isEditorInput, IEditorIdentifier } from 'vs/workbench/common/editor';
 import { isEqual } from 'vs/base/common/resources';
 import { ConfirmResult } from 'vs/platform/dialogs/common/dialogs';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 export interface IEditorCloseHandler {
 
@@ -124,6 +125,10 @@ export abstract class EditorInput extends AbstractEditorInput {
 		return (this.capabilities & capability) !== 0;
 	}
 
+	isReadonly(): boolean | IMarkdownString | undefined {
+		return this.hasCapability(EditorInputCapabilities.Readonly);
+	}
+
 	/**
 	 * Returns the display name of this input.
 	 */

src/vs/workbench/common/editor/textDiffEditorModel.ts

@@ -6,6 +6,7 @@
 import { IDiffEditorModel } from 'vs/editor/common/editorCommon';
 import { BaseTextEditorModel } from 'vs/workbench/common/editor/textEditorModel';
 import { DiffEditorModel } from 'vs/workbench/common/editor/diffEditorModel';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 /**
  * The base text editor model for the diff editor. It is made up of two text editor models, the original version
@@ -60,7 +61,7 @@ export class TextDiffEditorModel extends DiffEditorModel {
 		return !!this._textDiffEditorModel;
 	}
 
-	isReadonly(): boolean {
+	isReadonly(): boolean | IMarkdownString {
 		return !!this.modifiedModel && this.modifiedModel.isReadonly();
 	}
 

src/vs/workbench/common/editor/textEditorModel.ts

@@ -17,6 +17,7 @@ import { ILanguageDetectionService, LanguageDetectionLanguageEventSource } from
 import { ThrottledDelayer } from 'vs/base/common/async';
 import { IAccessibilityService } from 'vs/platform/accessibility/common/accessibility';
 import { localize } from 'vs/nls';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 /**
  * The base text editor model leverages the code editor model. This class is only intended to be subclassed and not instantiated.
@@ -71,7 +72,7 @@ export class BaseTextEditorModel extends EditorModel implements ITextEditorModel
 		return this.textEditorModelHandle ? this.modelService.getModel(this.textEditorModelHandle) : null;
 	}
 
-	isReadonly(): boolean {
+	isReadonly(): boolean | IMarkdownString {
 		return true;
 	}
 

src/vs/workbench/contrib/customEditor/common/customTextEditorModel.ts

@@ -64,7 +64,7 @@ export class CustomTextEditorModel extends Disposable implements ICustomEditorMo
 	}
 
 	public isReadonly(): boolean {
-		return this._model.object.isReadonly();
+		return !!this._model.object.isReadonly();
 	}
 
 	public get backupId() {

src/vs/workbench/contrib/files/browser/editors/fileEditorInput.ts

@@ -25,6 +25,7 @@ import { createTextBufferFactory } from 'vs/editor/common/model/textModel';
 import { IPathService } from 'vs/workbench/services/path/common/pathService';
 import { ITextResourceConfigurationService } from 'vs/editor/common/services/textResourceConfiguration';
 import { isConfigured } from 'vs/platform/configuration/common/configuration';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 const enum ForceOpenAs {
 	None,
@@ -192,6 +193,10 @@ export class FileEditorInput extends AbstractTextResourceEditorInput implements
 		return this.preferredName;
 	}
 
+	override isReadonly(): boolean | IMarkdownString | undefined {
+		return this.model ? this.model.isReadonly() : super.isReadonly();
+	}
+
 	override getDescription(verbosity?: Verbosity): string | undefined {
 		return this.preferredDescription || super.getDescription(verbosity);
 	}

src/vs/workbench/contrib/files/browser/editors/textFileEditor.ts

@@ -147,7 +147,7 @@ export class TextFileEditor extends AbstractTextCodeEditor<ICodeEditorViewState>
 			// was already asked for being readonly or not. The rationale is that
 			// a resolved model might have more specific information about being
 			// readonly or not that the input did not have.
-			control.updateOptions({ readOnly: textFileModel.isReadonly() });
+			control.updateOptions(this.readonlyValues(textFileModel.isReadonly()));
 		} catch (error) {
 			await this.handleSetInputError(error, input, options);
 		}

src/vs/workbench/contrib/files/common/explorerModel.ts

@@ -149,7 +149,7 @@ export class ExplorerItem {
 	}
 
 	get isReadonly(): boolean {
-		return this.filesConfigService.isReadonly(this.resource, { resource: this.resource, name: this.name, readonly: this._readonly, locked: this._locked });
+		return !!this.filesConfigService.isReadonly(this.resource, { resource: this.resource, name: this.name, readonly: this._readonly, locked: this._locked });
 	}
 
 	get mtime(): number | undefined {

src/vs/workbench/contrib/notebook/common/notebookCommon.ts

@@ -795,7 +795,7 @@ export interface INotebookEditorModel extends IEditorModel {
 	readonly notebook: INotebookTextModel | undefined;
 	isResolved(): this is IResolvedNotebookEditorModel;
 	isDirty(): boolean;
-	isReadonly(): boolean;
+	isReadonly(): boolean | IMarkdownString;
 	isOrphaned(): boolean;
 	hasAssociatedFilePath(): boolean;
 	load(options?: INotebookLoadOptions): Promise<IResolvedNotebookEditorModel>;

src/vs/workbench/contrib/notebook/common/notebookEditorModel.ts

@@ -7,6 +7,7 @@ import { VSBufferReadableStream, bufferToStream, streamToBuffer } from 'vs/base/
 import { CancellationToken } from 'vs/base/common/cancellation';
 import { CancellationError } from 'vs/base/common/errors';
 import { Emitter, Event } from 'vs/base/common/event';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 import { Disposable, DisposableStore } from 'vs/base/common/lifecycle';
 import { Schemas } from 'vs/base/common/network';
 import { filter } from 'vs/base/common/objects';
@@ -100,13 +101,11 @@ export class SimpleNotebookEditorModel extends EditorModel implements INotebookE
 		return !SimpleNotebookEditorModel._isStoredFileWorkingCopy(this._workingCopy) && !!this._workingCopy?.hasAssociatedFilePath;
 	}
 
-	isReadonly(): boolean {
+	isReadonly(): boolean | IMarkdownString {
 		if (SimpleNotebookEditorModel._isStoredFileWorkingCopy(this._workingCopy)) {
 			return this._workingCopy?.isReadonly();
-		} else if (this._filesConfigurationService.isReadonly(this.resource)) {
-			return true;
 		} else {
-			return false;
+			return this._filesConfigurationService.isReadonly(this.resource);
 		}
 	}
 

src/vs/workbench/services/extensions/common/extensionsApiProposals.ts

@@ -69,6 +69,7 @@ export const allApiProposals = Object.freeze({
 	quickPickItemIcon: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.quickPickItemIcon.d.ts',
 	quickPickItemTooltip: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.quickPickItemTooltip.d.ts',
 	quickPickSortByLabel: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.quickPickSortByLabel.d.ts',
+	readonlyMessage: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.readonlyMessage.d.ts',
 	resolvers: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.resolvers.d.ts',
 	saveEditor: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.saveEditor.d.ts',
 	scmActionButton: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.scmActionButton.d.ts',

src/vs/workbench/services/filesConfiguration/common/filesConfigurationService.ts

@@ -20,6 +20,7 @@ import { IUriIdentityService } from 'vs/platform/uriIdentity/common/uriIdentity'
 import { IEnvironmentService } from 'vs/platform/environment/common/environment';
 import { ResourceMap } from 'vs/base/common/map';
 import { withNullAsUndefined } from 'vs/base/common/types';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 export const AutoSaveAfterShortDelayContext = new RawContextKey<boolean>('autoSaveAfterShortDelayContext', false, true);
 
@@ -59,7 +60,7 @@ export interface IFilesConfigurationService {
 
 	readonly onReadonlyChange: Event<void>;
 
-	isReadonly(resource: URI, stat?: IBaseFileStat): boolean;
+	isReadonly(resource: URI, stat?: IBaseFileStat): boolean | IMarkdownString;
 
 	updateReadonly(resource: URI, readonly: true | false | 'toggle' | 'reset'): Promise<void>;
 
@@ -103,7 +104,7 @@ export class FilesConfigurationService extends Disposable implements IFilesConfi
 	private readonly readonlyExcludeMatcher = this._register(new IdleValue(() => this.createReadonlyMatcher(FILES_READONLY_EXCLUDE_CONFIG)));
 	private configuredReadonlyFromPermissions: boolean | undefined;
 
-	private readonly sessionReadonlyOverrides = new ResourceMap<boolean>(resource => this.uriIdentityService.extUri.getComparisonKey(resource));
+	private readonly sessionReadonlyOverrides = new ResourceMap<boolean | IMarkdownString>(resource => this.uriIdentityService.extUri.getComparisonKey(resource));
 
 	constructor(
 		@IContextKeyService contextKeyService: IContextKeyService,
@@ -140,13 +141,13 @@ export class FilesConfigurationService extends Disposable implements IFilesConfi
 		return matcher;
 	}
 
-	isReadonly(resource: URI, stat?: IBaseFileStat): boolean {
+	isReadonly(resource: URI, stat?: IBaseFileStat): boolean | IMarkdownString {
 
 		// if the entire file system provider is readonly, we respect that
 		// and do not allow to change readonly. we take this as a hint that
 		// the provider has no capabilities of writing.
 		if (this.fileService.hasCapability(resource, FileSystemProviderCapabilities.Readonly)) {
-			return true;
+			return this.fileService.getProvider(resource.scheme)?.readOnlyMessage ?? true;
 		}
 
 		// session override always wins over the others

src/vs/workbench/services/textfile/common/textFileEditorModel.ts

@@ -32,6 +32,7 @@ import { extUri } from 'vs/base/common/resources';
 import { IAccessibilityService } from 'vs/platform/accessibility/common/accessibility';
 import { PLAINTEXT_LANGUAGE_ID } from 'vs/editor/common/languages/modesRegistry';
 import { IExtensionService } from 'vs/workbench/services/extensions/common/extensions';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 interface IBackupMetaData extends IWorkingCopyBackupMeta {
 	mtime: number;
@@ -1163,7 +1164,7 @@ export class TextFileEditorModel extends BaseTextEditorModel implements ITextFil
 		return !!this.textEditorModel;
 	}
 
-	override isReadonly(): boolean {
+	override isReadonly(): boolean | IMarkdownString {
 		return this.filesConfigurationService.isReadonly(this.resource, this.lastResolvedFileStat);
 	}
 

src/vs/workbench/services/workingCopy/common/storedFileWorkingCopy.ts

@@ -28,6 +28,7 @@ import { IEditorService } from 'vs/workbench/services/editor/common/editorServic
 import { IElevatedFileService } from 'vs/workbench/services/files/common/elevatedFileService';
 import { IResourceWorkingCopy, ResourceWorkingCopy } from 'vs/workbench/services/workingCopy/common/resourceWorkingCopy';
 import { IFileWorkingCopy, IFileWorkingCopyModel, IFileWorkingCopyModelFactory } from 'vs/workbench/services/workingCopy/common/fileWorkingCopy';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 /**
  * Stored file specific working copy model factory.
@@ -145,7 +146,7 @@ export interface IStoredFileWorkingCopy<M extends IStoredFileWorkingCopyModel> e
 	/**
 	 * Whether the stored file working copy is readonly or not.
 	 */
-	isReadonly(): boolean;
+	isReadonly(): boolean | IMarkdownString;
 }
 
 export interface IResolvedStoredFileWorkingCopy<M extends IStoredFileWorkingCopyModel> extends IStoredFileWorkingCopy<M> {
@@ -1247,7 +1248,7 @@ export class StoredFileWorkingCopy<M extends IStoredFileWorkingCopyModel> extend
 
 	//#region Utilities
 
-	isReadonly(): boolean {
+	isReadonly(): boolean | IMarkdownString {
 		return this.filesConfigurationService.isReadonly(this.resource, this.lastResolvedFileStat);
 	}
 

src/vscode-dts/vscode.proposed.readonlyMessage.d.ts

@@ -0,0 +1,14 @@
+/*---------------------------------------------------------------------------------------------
+ *  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/166971
+
+declare module 'vscode' {
+
+	export namespace workspace {
+
+		export function registerFileSystemProvider(scheme: string, provider: FileSystemProvider, options?: { readonly isCaseSensitive?: boolean; readonly isReadonly?: boolean | MarkdownString }): Disposable;
+	}
+}