add preloads to notebook controller, fyi @connor4312 NotebookKernel will go out soon

src/vs/vscode.proposed.d.ts

@@ -1480,9 +1480,10 @@ declare module 'vscode' {
 
 		// UI properties (get/set)
 		label: string;
-		description: string;
 		supportedLanguages: string[];
-		hasExecutionOrder: boolean;
+		description?: string;
+		hasExecutionOrder?: boolean;
+		preloads?: NotebookKernelPreload[];
 
 		/**
 		 * The execute handler is invoked when the run gestures in the UI are selected, e.g Run Cell, Run All,

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

@@ -11,7 +11,7 @@ import { ExtHostNotebookController } from 'vs/workbench/api/common/extHostNotebo
 import { IExtensionDescription } from 'vs/platform/extensions/common/extensions';
 import { URI, UriComponents } from 'vs/base/common/uri';
 import { ICellRange } from 'vs/workbench/contrib/notebook/common/notebookCommon';
-import { NotebookCellRange } from 'vs/workbench/api/common/extHostTypeConverters';
+import * as extHostTypeConverters from 'vs/workbench/api/common/extHostTypeConverters';
 import { isNonEmptyArray } from 'vs/base/common/arrays';
 
 type ExecuteHandler = (cells: vscode.NotebookCell[], controller: vscode.NotebookController) => void;
@@ -105,6 +105,13 @@ export class ExtHostNotebookKernels implements ExtHostNotebookKernelsShape {
 				data.hasExecutionOrder = value;
 				_update();
 			},
+			get preloads() {
+				return data.preloads && data.preloads.map(extHostTypeConverters.NotebookKernelPreload.to);
+			},
+			set preloads(value) {
+				data.preloads = value && value.map(extHostTypeConverters.NotebookKernelPreload.from);
+				_update();
+			},
 			get executeHandler() {
 				return _executeHandler;
 			},
@@ -118,7 +125,7 @@ export class ExtHostNotebookKernels implements ExtHostNotebookKernelsShape {
 			},
 			createNotebookCellExecutionTask(cell) {
 				if (isDisposed) {
-					throw new Error('object disposed');
+					throw new Error('notebook controller is DISPOSED');
 				}
 				//todo@jrieken
 				return that._extHostNotebook.createNotebookCellExecution(cell.notebook.uri, cell.index, data.id)!;
@@ -166,7 +173,7 @@ export class ExtHostNotebookKernels implements ExtHostNotebookKernelsShape {
 
 		const cells: vscode.NotebookCell[] = [];
 		for (let range of ranges) {
-			cells.push(...document.notebookDocument.getCells(NotebookCellRange.to(range)));
+			cells.push(...document.notebookDocument.getCells(extHostTypeConverters.NotebookCellRange.to(range)));
 		}
 
 		try {

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

@@ -1646,6 +1646,23 @@ export namespace NotebookDocumentContentOptions {
 	}
 }
 
+export namespace NotebookKernelPreload {
+	export function from(preload: vscode.NotebookKernelPreload): { uri: UriComponents; provides: string[] } {
+		return {
+			uri: preload.uri,
+			provides: typeof preload.provides === 'string'
+				? [preload.provides]
+				: preload.provides ?? []
+		};
+	}
+	export function to(preload: { uri: UriComponents; provides: string[] }): vscode.NotebookKernelPreload {
+		return {
+			uri: URI.revive(preload.uri),
+			provides: preload.provides
+		};
+	}
+}
+
 export namespace TestMessage {
 	export function from(message: vscode.TestMessage): ITestMessage {
 		return {