Add total portfolio value, cached prices and balances

Total USD value displayed in 2x type above wallet list on Home.
Value aggregation: getAddressValueUsd (ETH + all tokens) →
getWalletValueUsd → getTotalValueUsd. Price API cached for 5
minutes, balance fetches cached for 60 seconds. Both caches
are app-wide — repeated calls to refreshPrices/refreshBalances
are no-ops within the TTL.

src/popup/index.js

@@ -129,16 +129,27 @@ function addressFromPrivateKey(key) {
     return w.address;
 }
 
-// -- price fetching --
+// -- caching layer --
+const PRICE_CACHE_TTL = 300000; // 5 minutes
+const BALANCE_CACHE_TTL = 60000; // 60 seconds
+
+const cache = {
+    prices: { data: {}, fetchedAt: 0 },
+    balances: { fetchedAt: 0 },
+};
+
 // { "ETH": 1234.56, "LINK": 8.60, ... }
 const prices = {};
 
 async function refreshPrices() {
+    const now = Date.now();
+    if (now - cache.prices.fetchedAt < PRICE_CACHE_TTL) return;
     try {
         const fetched = await getTopTokenPrices(25);
         Object.assign(prices, fetched);
+        cache.prices.fetchedAt = now;
     } catch (e) {
-        // prices stay empty on error
+        // prices stay stale on error
     }
 }
 
@@ -187,11 +198,12 @@ function formatBalance(wei) {
 }
 
 async function refreshBalances() {
+    const now = Date.now();
+    if (now - cache.balances.fetchedAt < BALANCE_CACHE_TTL) return;
     const provider = getProvider();
     const updates = [];
     for (const wallet of state.wallets) {
         for (const addr of wallet.addresses) {
-            // Fetch ETH balance
             updates.push(
                 provider
                     .getBalance(addr.address)
@@ -200,7 +212,6 @@ async function refreshBalances() {
                     })
                     .catch(() => {}),
             );
-            // Reverse ENS lookup
             updates.push(
                 provider
                     .lookupAddress(addr.address)
@@ -214,15 +225,54 @@ async function refreshBalances() {
         }
     }
     await Promise.all(updates);
+    cache.balances.fetchedAt = now;
     await saveState();
 }
 
+function getAddressValueUsd(addr) {
+    let total = 0;
+    const ethBal = parseFloat(addr.balance || "0");
+    if (prices.ETH) {
+        total += ethBal * prices.ETH;
+    }
+    for (const token of addr.tokens || []) {
+        const tokenBal = parseFloat(token.balance || "0");
+        if (tokenBal > 0 && prices[token.symbol]) {
+            total += tokenBal * prices[token.symbol];
+        }
+    }
+    return total;
+}
+
+function getWalletValueUsd(wallet) {
+    let total = 0;
+    for (const addr of wallet.addresses) {
+        total += getAddressValueUsd(addr);
+    }
+    return total;
+}
+
+function getTotalValueUsd() {
+    let total = 0;
+    for (const wallet of state.wallets) {
+        total += getWalletValueUsd(wallet);
+    }
+    return total;
+}
+
+function renderTotalValue() {
+    const el = $("total-value");
+    if (!el) return;
+    el.textContent = formatUsd(getTotalValueUsd());
+}
+
 // -- render wallet list on main view --
 function renderWalletList() {
     const container = $("wallet-list");
     if (state.wallets.length === 0) {
         container.innerHTML =
             '<p class="text-muted py-2">No wallets yet. Add one to get started.</p>';
+        renderTotalValue();
         return;
     }
 
@@ -244,12 +294,8 @@ function renderWalletList() {
             html += `<div class="text-xs break-all">${addr.address}</div>`;
             html += `<div class="flex justify-between items-center">`;
             html += `<span class="text-xs">${addr.balance} ETH</span>`;
-            const ethUsd = prices.ETH
-                ? parseFloat(addr.balance) * prices.ETH
-                : null;
-            if (ethUsd !== null) {
-                html += `<span class="text-xs text-muted">${formatUsd(ethUsd)}</span>`;
-            }
+            const addrUsd = getAddressValueUsd(addr);
+            html += `<span class="text-xs text-muted">${formatUsd(addrUsd)}</span>`;
             html += `</div>`;
             html += `</div>`;
         });
@@ -285,6 +331,8 @@ function renderWalletList() {
             renderWalletList();
         });
     });
+
+    renderTotalValue();
 }
 
 function showAddressDetail() {
@@ -294,9 +342,7 @@ function showAddressDetail() {
     $("address-full").textContent = addr.address;
     $("address-copied-msg").textContent = "";
     $("address-eth-balance").textContent = addr.balance;
-    const ethUsd = prices.ETH ? parseFloat(addr.balance) * prices.ETH : null;
-    $("address-usd-value").textContent =
-        ethUsd !== null ? formatUsd(ethUsd) : "";
+    $("address-usd-value").textContent = formatUsd(getAddressValueUsd(addr));
     const ensEl = $("address-ens");
     if (addr.ensName) {
         ensEl.textContent = addr.ensName;