diff --git a/.eslintrc.json b/.eslintrc.json
index 06eeba25e8d..9154bc2f60b 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -322,7 +322,6 @@
 					"vs/editor/~",
 					"vs/editor/contrib/*/~",
 					"vs/workbench/~",
-					"vs/workbench/api/~",
 					"vs/workbench/services/*/~",
 					{ "when": "test", "pattern": "vs/workbench/contrib/*/~" }, // TODO@layers
 					"tas-client-umd", // node module allowed even in /common/
diff --git a/src/vs/workbench/api/browser/mainThreadExtensionService.ts b/src/vs/workbench/api/browser/mainThreadExtensionService.ts
index efe0a38d024..a7d7d850745 100644
--- a/src/vs/workbench/api/browser/mainThreadExtensionService.ts
+++ b/src/vs/workbench/api/browser/mainThreadExtensionService.ts
@@ -44,10 +44,13 @@ export class MainThreadExtensionService implements MainThreadExtensionServiceSha
 		@IWorkbenchEnvironmentService protected readonly _environmentService: IWorkbenchEnvironmentService,
 	) {
 		this._extensionHostKind = extHostContext.extensionHostKind;
-		this._internalExtensionService = (<IInternalExtHostContext>extHostContext).internalExtensionService;
-		(<IInternalExtHostContext>extHostContext)._setExtensionHostProxy(
+
+		const internalExtHostContext = (<IInternalExtHostContext>extHostContext);
+		this._internalExtensionService = internalExtHostContext.internalExtensionService;
+		internalExtHostContext._setExtensionHostProxy(
 			new ExtensionHostProxy(extHostContext.getProxy(ExtHostContext.ExtHostExtensionService))
 		);
+		internalExtHostContext._setAllMainProxyIdentifiers(Object.keys(MainContext).map((key) => (<any>MainContext)[key]));
 	}
 
 	public dispose(): void {
diff --git a/src/vs/workbench/services/extensions/common/extHostCustomers.ts b/src/vs/workbench/services/extensions/common/extHostCustomers.ts
index d33ba1a9ce8..a7d30a680e0 100644
--- a/src/vs/workbench/services/extensions/common/extHostCustomers.ts
+++ b/src/vs/workbench/services/extensions/common/extHostCustomers.ts
@@ -17,6 +17,7 @@ export interface IExtHostContext extends IRPCProtocol {
 export interface IInternalExtHostContext extends IExtHostContext {
 	readonly internalExtensionService: IInternalExtensionService;
 	_setExtensionHostProxy(extensionHostProxy: IExtensionHostProxy): void;
+	_setAllMainProxyIdentifiers(mainProxyIdentifiers: ProxyIdentifier<any>[]): void;
 }
 
 export type IExtHostNamedCustomer<T extends IDisposable> = [ProxyIdentifier<T>, IExtHostCustomerCtor<T>];
diff --git a/src/vs/workbench/services/extensions/common/extensionHostManager.ts b/src/vs/workbench/services/extensions/common/extensionHostManager.ts
index 8e1664e9c99..9e0dc443f4c 100644
--- a/src/vs/workbench/services/extensions/common/extensionHostManager.ts
+++ b/src/vs/workbench/services/extensions/common/extensionHostManager.ts
@@ -10,7 +10,6 @@ import { IMessagePassingProtocol } from 'vs/base/parts/ipc/common/ipc';
 import { IWorkbenchEnvironmentService } from 'vs/workbench/services/environment/common/environmentService';
 import { IInstantiationService, ServicesAccessor } from 'vs/platform/instantiation/common/instantiation';
 import { ExtHostCustomersRegistry, IInternalExtHostContext } from 'vs/workbench/services/extensions/common/extHostCustomers';
-import { MainContext } from 'vs/workbench/api/common/extHost.protocol';
 import { Proxied, ProxyIdentifier } from 'vs/workbench/services/extensions/common/proxyIdentifier';
 import { IRPCProtocolLogger, RPCProtocol, RequestInitiator, ResponsiveState } from 'vs/workbench/services/extensions/common/rpcProtocol';
 import { RemoteAuthorityResolverError, ResolverResult } from 'vs/platform/remote/common/remoteAuthorityResolver';
@@ -261,6 +260,7 @@ class ExtensionHostManager extends Disposable implements IExtensionHostManager {
 		this._rpcProtocol = new RPCProtocol(protocol, logger);
 		this._register(this._rpcProtocol.onDidChangeResponsiveState((responsiveState: ResponsiveState) => this._onDidChangeResponsiveState.fire(responsiveState)));
 		let extensionHostProxy: IExtensionHostProxy | null = null as IExtensionHostProxy | null;
+		let mainProxyIdentifiers: ProxyIdentifier<any>[] = [];
 		const extHostContext: IInternalExtHostContext = {
 			remoteAuthority: this._extensionHost.remoteAuthority,
 			extensionHostKind: this.kind,
@@ -274,6 +274,9 @@ class ExtensionHostManager extends Disposable implements IExtensionHostManager {
 			_setExtensionHostProxy: (value: IExtensionHostProxy): void => {
 				extensionHostProxy = value;
 			},
+			_setAllMainProxyIdentifiers: (value: ProxyIdentifier<any>[]): void => {
+				mainProxyIdentifiers = value;
+			},
 			//#endregion
 		};
 
@@ -298,8 +301,7 @@ class ExtensionHostManager extends Disposable implements IExtensionHostManager {
 		}
 
 		// Check that no named customers are missing
-		const expected: ProxyIdentifier<any>[] = Object.keys(MainContext).map((key) => (<any>MainContext)[key]);
-		this._rpcProtocol.assertRegistered(expected);
+		this._rpcProtocol.assertRegistered(mainProxyIdentifiers);
 
 		return extensionHostProxy;
 	}