mcp: adopt proposed completions fix (microsoft#250050)

Refs modelcontextprotocol/modelcontextprotocol#598

Also fixes a bug I noticed where we sometimes didn't put templates in the quickpick

Author: connor4312

src/vs/workbench/contrib/mcp/browser/mcpResourceQuickAccess.ts

@@ -119,19 +119,15 @@ export class McpResourcePickHelper {
 		const cts = new CancellationTokenSource();
 
 		const vars: Record<string, string | string[]> = {};
-		for (const variable of todo) {
-			vars[variable.name] = `$${variable.name.toUpperCase()}`;
-		}
-
 		quickInput.totalSteps = todo.length;
 		quickInput.ignoreFocusOut = true;
 
-		const initialCompletions = todo.map(variable => rt.complete(variable.name, '', cts.token));
+		const initialCompletions = todo.map(variable => rt.complete(variable.name, '', {}, cts.token));
 
 		try {
 			for (let i = 0; i < todo.length; i++) {
 				const variable = todo[i];
-				const resolved = await this._promptForTemplateValue(quickInput, variable, initialCompletions[i], rt.template.resolve(vars), rt);
+				const resolved = await this._promptForTemplateValue(quickInput, variable, initialCompletions[i], vars, rt);
 				if (resolved === undefined) {
 					return undefined;
 				}
@@ -144,11 +140,18 @@ export class McpResourcePickHelper {
 		}
 	}
 
-	private _promptForTemplateValue(input: IQuickPick<IQuickPickItem>, variable: IUriTemplateVariable, initialCompletions: Promise<string[]>, uriSoFar: string, rt: IMcpResourceTemplate): Promise<string | undefined> {
+	private _promptForTemplateValue(input: IQuickPick<IQuickPickItem>, variable: IUriTemplateVariable, initialCompletions: Promise<string[]>, variablesSoFar: Record<string, string | string[]>, rt: IMcpResourceTemplate): Promise<string | undefined> {
 		const store = new DisposableStore();
 		const completions = new Map<string, Promise<string[]>>([['', initialCompletions]]);
 
-		let placeholder = localize('mcp.resource.template.placeholder', "Value for ${0} in {1}", variable.name.toUpperCase(), uriSoFar.replaceAll('%24', '$'));
+		const variablesWithPlaceholders = { ...variablesSoFar };
+		for (const variable of rt.template.components.flatMap(c => typeof c === 'object' ? c.variables : [])) {
+			if (!variablesWithPlaceholders.hasOwnProperty(variable.name)) {
+				variablesWithPlaceholders[variable.name] = `$${variable.name.toUpperCase()}`;
+			}
+		}
+
+		let placeholder = localize('mcp.resource.template.placeholder', "Value for ${0} in {1}", variable.name.toUpperCase(), rt.template.resolve(variablesWithPlaceholders).replaceAll('%24', '$'));
 		if (variable.optional) {
 			placeholder += ' (' + localize('mcp.resource.template.optional', "Optional") + ')';
 		}
@@ -174,7 +177,7 @@ export class McpResourcePickHelper {
 			const inputValue = input.value;
 			let promise = completions.get(inputValue);
 			if (!promise) {
-				promise = rt.complete(variable.name, inputValue, changeCancellation.token);
+				promise = rt.complete(variable.name, inputValue, variablesSoFar, changeCancellation.token);
 				completions.set(inputValue, promise);
 			}
 
@@ -240,6 +243,7 @@ export class McpResourcePickHelper {
 				})(),
 				server.resourceTemplates(cts.token).then(templates => {
 					writeInto.unshift(...templates);
+					onChange(servers);
 				}).catch(() => {
 					// no templat support, not rare
 				}),

src/vs/workbench/contrib/mcp/common/mcpServer.ts

@@ -8,6 +8,7 @@ import { CancellationToken, CancellationTokenSource } from '../../../../base/com
 import * as json from '../../../../base/common/json.js';
 import { Disposable, DisposableStore, IDisposable, toDisposable } from '../../../../base/common/lifecycle.js';
 import { LRUCache } from '../../../../base/common/map.js';
+import { mapValues } from '../../../../base/common/objects.js';
 import { autorun, autorunWithStore, derived, disposableObservableValue, IDerivedReader, IObservable, ITransaction, observableFromEvent, ObservablePromise, observableValue, transaction } from '../../../../base/common/observable.js';
 import { basename } from '../../../../base/common/resources.js';
 import { URI } from '../../../../base/common/uri.js';
@@ -842,10 +843,11 @@ class McpResourceTemplate implements IMcpResourceTemplate {
 		return McpResourceURI.fromServer(this._server.definition, serverUri);
 	}
 
-	async complete(templatePart: string, prefix: string, token?: CancellationToken): Promise<string[]> {
+	async complete(templatePart: string, prefix: string, alreadyResolved: Record<string, string | string[]>, token?: CancellationToken): Promise<string[]> {
 		const result = await McpServer.callOn(this._server, h => h.complete({
 			ref: { type: 'ref/resource', uri: this._definition.uriTemplate },
-			argument: { name: templatePart, value: prefix, }
+			argument: { name: templatePart, value: prefix },
+			resolved: mapValues(alreadyResolved, v => Array.isArray(v) ? v.join('/') : v),
 		}, token), token);
 		return result.completion.values;
 	}

src/vs/workbench/contrib/mcp/common/mcpServerRequestHandler.ts

@@ -521,7 +521,7 @@ export class McpServerRequestHandler extends Disposable {
 	/**
 	 * Find completions for an argument
 	 */
-	complete(params: MCP.CompleteRequest['params'], token?: CancellationToken): Promise<MCP.CompleteResult> {
-		return this.sendRequest<MCP.CompleteRequest, MCP.CompleteResult>({ method: 'completion/complete', params }, token);
+	complete(params: MCP.CompleteRequest2['params'], token?: CancellationToken): Promise<MCP.CompleteResult> {
+		return this.sendRequest<MCP.CompleteRequest2, MCP.CompleteResult>({ method: 'completion/complete', params }, token);
 	}
 }

src/vs/workbench/contrib/mcp/common/mcpTypes.ts

@@ -295,7 +295,7 @@ export interface IMcpResourceTemplate {
 	readonly template: UriTemplate;
 
 	/** Gets string completions for the given template part. */
-	complete(templatePart: string, prefix: string, token: CancellationToken): Promise<string[]>;
+	complete(templatePart: string, prefix: string, alreadyResolved: Record<string, string | string[]>, token: CancellationToken): Promise<string[]>;
 
 	/** Gets the resolved URI from template parts. */
 	resolveURI(vars: Record<string, unknown>): URI;

src/vs/workbench/contrib/mcp/common/modelContextProtocol.ts

@@ -5,6 +5,29 @@
 
 /* eslint-disable local/code-no-unexternalized-strings */
 
+//#region proposals
+/**
+ * MCP protocol proposals.
+ * - Proposals here MUST have an MCP PR linked to them
+ * - Proposals here are subject to change and SHALL be removed when
+ *   the upstream MCP PR is merged or closed.
+ */
+export namespace MCP {
+
+	// https://github.com/modelcontextprotocol/modelcontextprotocol/pull/598
+	export interface CompleteRequest2 extends MCP.CompleteRequest {
+		params: MCP.CompleteRequest['params'] & {
+			/**
+			 * Previously-resolved variables in a URI template. The keys of the object
+			 * are be the template's variable expressions including surrounding braces.
+			 */
+			resolved?: { [key: string]: string };
+		};
+	}
+}
+
+//#endregion
+
 /**
  * Schema updated from the Model Context Protocol repository at
  * https://github.com/modelcontextprotocol/specification/tree/main/schema