plugins: support flat MCP server map format in .mcp.json

src/vs/workbench/contrib/chat/common/plugins/agentPluginServiceImpl.ts

@@ -137,6 +137,22 @@ export function shellQuotePluginRootInCommand(command: string, fsPath: string, t
 	});
 }
 
+/**
+ * Extracts the MCP server map from a raw JSON value. Accepts both the
+ * wrapped format `{ mcpServers: { … } }` (Claude `.mcp.json`) and the
+ * flat format where server entries are at the top level.
+ * Returns `undefined` when the input is not a usable object.
+ */
+export function resolveMcpServersMap(raw: unknown): Record<string, unknown> | undefined {
+	if (!raw || typeof raw !== 'object' || Array.isArray(raw)) {
+		return undefined;
+	}
+	const obj = raw as Record<string, unknown>;
+	return Object.hasOwn(obj, 'mcpServers')
+		? (obj.mcpServers as Record<string, unknown>)
+		: obj;
+}
+
 /**
  * Replaces `${token}` references in MCP server definition string fields
  * (command, args, cwd, env values, url, envFile, headers) with the plugin
@@ -671,12 +687,13 @@ export abstract class AbstractAgentPluginDiscovery extends Disposable implements
 	}
 
 	private _parseMcpServerDefinitionMap(raw: unknown, pluginFsPath: string, adapter: IAgentPluginFormatAdapter): IAgentPluginMcpServerDefinition[] {
-		if (!raw || typeof raw !== 'object' || !raw.hasOwnProperty('mcpServers')) {
+		const mcpServers = resolveMcpServersMap(raw);
+		if (!mcpServers) {
 			return [];
 		}
 
 		const definitions: IAgentPluginMcpServerDefinition[] = [];
-		for (const [name, configValue] of Object.entries((raw as { mcpServers: Record<string, unknown> }).mcpServers)) {
+		for (const [name, configValue] of Object.entries(mcpServers)) {
 			const configuration = this._normalizeMcpServerConfiguration(configValue);
 			if (!configuration) {
 				continue;

src/vs/workbench/contrib/chat/test/common/plugins/resolveMcpServersMap.test.ts

@@ -0,0 +1,52 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import assert from 'assert';
+import { ensureNoDisposablesAreLeakedInTestSuite } from '../../../../../../base/test/common/utils.js';
+import { resolveMcpServersMap } from '../../../common/plugins/agentPluginServiceImpl.js';
+
+suite('resolveMcpServersMap', () => {
+	ensureNoDisposablesAreLeakedInTestSuite();
+
+	test('returns undefined for null', () => {
+		assert.strictEqual(resolveMcpServersMap(null), undefined);
+	});
+
+	test('returns undefined for undefined', () => {
+		assert.strictEqual(resolveMcpServersMap(undefined), undefined);
+	});
+
+	test('returns undefined for non-object primitives', () => {
+		assert.strictEqual(resolveMcpServersMap('string'), undefined);
+		assert.strictEqual(resolveMcpServersMap(42), undefined);
+		assert.strictEqual(resolveMcpServersMap(true), undefined);
+	});
+
+	test('unwraps mcpServers property when present', () => {
+		const servers = { myServer: { command: 'node' } };
+		const result = resolveMcpServersMap({ mcpServers: servers });
+		assert.deepStrictEqual(result, servers);
+	});
+
+	test('returns the object directly when mcpServers is absent', () => {
+		const servers = { myServer: { command: 'node' }, otherServer: { url: 'http://localhost' } };
+		const result = resolveMcpServersMap(servers);
+		assert.deepStrictEqual(result, servers);
+	});
+
+	test('returns empty object for empty wrapped format', () => {
+		assert.deepStrictEqual(resolveMcpServersMap({ mcpServers: {} }), {});
+	});
+
+	test('returns empty object for empty flat format', () => {
+		assert.deepStrictEqual(resolveMcpServersMap({}), {});
+	});
+
+	test('prefers mcpServers property over other top-level keys', () => {
+		const inner = { realServer: { command: 'python' } };
+		const result = resolveMcpServersMap({ mcpServers: inner, someOtherKey: 'ignored' });
+		assert.deepStrictEqual(result, inner);
+	});
+});