feat: multi-wallet architecture with localStorage state, EIP-712 verification, cross-tab WS leadership

- wallets.js: WalletManager state management with chain validation
- verifier.js: WalletVerifier EIP-712 signing via window.ethereum
- stream.js: WalletStreamManager with BroadcastChannel leader election, backoff + jitter
- AGENTS.md: updated with coding guidelines

test/test_verifier.js

@@ -0,0 +1,76 @@
+import { WalletManager } from '../wallets.js';
+import { WalletVerifier } from '../verifier.js';
+
+// Setup basic environment mocks
+const mockStorage = {};
+globalThis.localStorage = {
+  getItem: (key) => mockStorage[key] || null,
+  setItem: (key, value) => { mockStorage[key] = String(value); }
+};
+
+function assertError(result, expectedMsg, testName) {
+  if (result.success === false && result.error.includes(expectedMsg)) {
+    console.log(`✅ PASS: ${testName}`);
+  } else {
+    console.error(`❌ FAIL: ${testName} (Got: "${result.error ?? 'success'}", Expected: "${expectedMsg}")`);
+  }
+}
+
+async function runVerifierTests() {
+  console.log("🚀 Starting WalletVerifier Error State Test Suite...\n");
+
+  // --- TEST 1: Missing Extension ---
+  globalThis.window = {}; // No ethereum provider defined
+  const wm1 = new WalletManager();
+  let verifier = new WalletVerifier(wm1);
+  assertError(
+    await verifier.triggerWalletVerification('base', 'Test'),
+    "No Web3 wallet extension found",
+    "Missing Extension Detection"
+  );
+
+  // --- TEST 2: User Rejects Account Connection (EIP-1193 Error 4001) ---
+  globalThis.window = {
+    ethereum: {
+      request: async ({ method }) => {
+        if (method === 'eth_requestAccounts') {
+          const err = new Error("User denied connection");
+          err.code = 4001;
+          throw err;
+        }
+      }
+    }
+  };
+  const wm2 = new WalletManager();
+  verifier = new WalletVerifier(wm2);
+  assertError(
+    await verifier.triggerWalletVerification('base', 'Test'),
+    "Verification cancelled",
+    "Account Rejection (Code 4001)"
+  );
+
+  // --- TEST 3: User Rejects Signature ---
+  globalThis.window = {
+    ethereum: {
+      request: async ({ method }) => {
+        if (method === 'eth_requestAccounts') return ['0x04f728C520C438A000f7A5E9d904F0e725FFAEFE'];
+        if (method === 'eth_signTypedData_v4') {
+          const err = new Error("User rejected the signature request");
+          err.code = 4001;
+          throw err;
+        }
+      }
+    }
+  };
+  const wm3 = new WalletManager();
+  verifier = new WalletVerifier(wm3);
+  assertError(
+    await verifier.triggerWalletVerification('base', 'Test'),
+    "rejected",
+    "Signature Rejection Mapping"
+  );
+
+  console.log("\n🏁 Test Suite Complete.");
+}
+
+runVerifierTests();