Fix #89462

src/vs/platform/userDataSync/common/extensionsSync.ts

@@ -237,18 +237,22 @@ export class ExtensionsSynchroniser extends AbstractSynchroniser implements IUse
 		}
 
 		if (added.length || updated.length) {
+			const installedExtensions = await this.extensionManagementService.getInstalled(ExtensionType.User);
 			await Promise.all([...added, ...updated].map(async e => {
 				const extension = await this.extensionGalleryService.getCompatibleExtension(e.identifier, e.version);
 				if (extension) {
 					this.logService.info('Extensions: Installing local extension.', e.identifier.id, extension.version);
 					try {
-						await this.extensionManagementService.installFromGallery(extension);
-						removeFromSkipped.push(extension.identifier);
 						if (e.enabled) {
 							await this.extensionEnablementService.enableExtension(extension.identifier);
 						} else {
 							await this.extensionEnablementService.disableExtension(extension.identifier);
 						}
+						// Install only if the extension does not exist
+						if (!installedExtensions.some(installed => areSameExtensions(installed.identifier, extension.identifier) && installed.manifest.version === extension.version)) {
+							await this.extensionManagementService.installFromGallery(extension);
+							removeFromSkipped.push(extension.identifier);
+						}
 					} catch (error) {
 						addToSkipped.push(e);
 						this.logService.error(error);

src/vs/workbench/contrib/extensions/browser/extensionsWorkbenchService.ts

@@ -508,12 +508,10 @@ export class ExtensionsWorkbenchService extends Disposable implements IExtension
 		if (extensionManagementServerService.localExtensionManagementServer) {
 			this.localExtensions = this._register(instantiationService.createInstance(Extensions, extensionManagementServerService.localExtensionManagementServer, ext => this.getExtensionState(ext)));
 			this._register(this.localExtensions.onChange(e => this._onChange.fire(e ? e.extension : undefined)));
-			this._register(Event.filter(this.localExtensions.onChange, e => !!e && e.operation === InstallOperation.Install)(e => this.onDidInstallExtension(e!.extension)));
 		}
 		if (extensionManagementServerService.remoteExtensionManagementServer) {
 			this.remoteExtensions = this._register(instantiationService.createInstance(Extensions, extensionManagementServerService.remoteExtensionManagementServer, ext => this.getExtensionState(ext)));
 			this._register(this.remoteExtensions.onChange(e => this._onChange.fire(e ? e.extension : undefined)));
-			this._register(Event.filter(this.remoteExtensions.onChange, e => !!e && e.operation === InstallOperation.Install)(e => this.onDidInstallExtension(e!.extension)));
 		}
 
 		this.syncDelayer = new ThrottledDelayer<void>(ExtensionsWorkbenchService.SyncPeriod);
@@ -888,10 +886,6 @@ export class ExtensionsWorkbenchService extends Disposable implements IExtension
 		}
 	}
 
-	private onDidInstallExtension(extension: IExtension): void {
-		this.setEnablement(extension, EnablementState.EnabledGlobally);
-	}
-
 	private promptAndSetEnablement(extensions: IExtension[], enablementState: EnablementState): Promise<any> {
 		const enable = enablementState === EnablementState.EnabledGlobally || enablementState === EnablementState.EnabledWorkspace;
 		if (enable) {