feat: add MetaMask detection functionality

package.json

@@ -79,7 +79,9 @@
     "allowScripts": {
       "@lavamoat/preinstall-always-fail": false,
       "vite>esbuild": false,
-      "@biomejs/biome": false
+      "@biomejs/biome": false,
+      "vitest>vite-node>vite>esbuild": false,
+      "vitest>vite>esbuild": false
     }
   }
 }

src/helpers/metamaskExtensionId.ts → src/helpers/metamask.ts

@@ -49,3 +49,56 @@ function isProviderMessage(event: MessageEvent) {
   const { target, data } = event.data;
   return target === INPAGE && data?.name === METAMASK_PROVIDER_STREAM_NAME && event.origin === location.origin;
 }
+
+// EIP-6963 types
+interface EIP6963ProviderInfo {
+  uuid: string;
+  name: string;
+  icon: string;
+  rdns: string;
+}
+
+interface EIP6963ProviderDetail {
+  info: EIP6963ProviderInfo;
+  provider: unknown;
+}
+
+interface EIP6963AnnounceProviderEvent extends CustomEvent {
+  type: 'eip6963:announceProvider';
+  detail: EIP6963ProviderDetail;
+}
+
+// Augment WindowEventMap to avoid type casting
+declare global {
+  interface WindowEventMap {
+    'eip6963:announceProvider': EIP6963AnnounceProviderEvent;
+    'eip6963:requestProvider': Event;
+  }
+}
+
+/**
+ * Checks if MetaMask is installed by listening for EIP-6963 provider announcements
+ * @param timeout - Maximum time to wait for the announcement (in ms)
+ * @returns Promise that resolves to true if MetaMask is installed, false otherwise
+ */
+export async function isMetamaskInstalled({ timeout = 2000 }: { timeout?: number } = {}): Promise<boolean> {
+  return new Promise((resolve) => {
+    const handleEip6963Announcement = (event: EIP6963AnnounceProviderEvent) => {
+      if (event.detail.info.rdns.includes('io.metamask')) {
+        window.removeEventListener('eip6963:announceProvider', handleEip6963Announcement);
+        clearTimeout(timeoutId);
+        resolve(true);
+      }
+    };
+
+    const timeoutId = setTimeout(() => {
+      window.removeEventListener('eip6963:announceProvider', handleEip6963Announcement);
+      resolve(false);
+    }, timeout);
+
+    // DApp MUST set up listener BEFORE dispatching request event
+    window.addEventListener('eip6963:announceProvider', handleEip6963Announcement);
+    // Dispatch request event to trigger announcements from wallets that loaded earlier
+    window.dispatchEvent(new Event('eip6963:requestProvider'));
+  });
+}

src/helpers/utils.ts

@@ -22,7 +22,7 @@ export const getUniqueId = (): number => {
  * Detects if we're in a Chrome-like environment with extension support
  */
 export const isChromeRuntime = (): boolean => {
-  return typeof chrome !== 'undefined' && chrome.runtime && typeof chrome.runtime.connect === 'function';
+  return typeof chrome !== 'undefined' && !!chrome.runtime && typeof chrome.runtime.connect === 'function';
 };
 
 /**

src/index.ts

@@ -38,3 +38,4 @@ export type * from './types/session';
 export type * from './types/multichainApi';
 export type * from './types/scopes';
 export * from './types/errors';
+export { isMetamaskInstalled } from './helpers/metamask';

src/transports/externallyConnectableTransport.test.ts

@@ -1,6 +1,6 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import { type MockPort, mockSession } from '../../tests/mocks';
-import * as metamaskExtensionId from '../helpers/metamaskExtensionId';
+import * as metamaskHelper from '../helpers/metamask';
 import * as utils from '../helpers/utils';
 import { TransportError } from '../types/errors';
 import { getExternallyConnectableTransport } from './externallyConnectableTransport';
@@ -60,7 +60,7 @@ describe('ExternallyConnectableTransport', () => {
   });
 
   it('should fetch extension id when not provided', async () => {
-    const detectSpy = vi.spyOn(metamaskExtensionId, 'detectMetamaskExtensionId').mockResolvedValue(testExtensionId);
+    const detectSpy = vi.spyOn(metamaskHelper, 'detectMetamaskExtensionId').mockResolvedValue(testExtensionId);
 
     const newTransport = getExternallyConnectableTransport({});
     await newTransport.connect();

src/transports/externallyConnectableTransport.ts

@@ -1,4 +1,4 @@
-import { detectMetamaskExtensionId } from '../helpers/metamaskExtensionId';
+import { detectMetamaskExtensionId } from '../helpers/metamask';
 import { getUniqueId, withTimeout } from '../helpers/utils';
 import { TransportError, TransportTimeoutError } from '../types/errors';
 import type { Transport, TransportResponse } from '../types/transport';