fix: read USD prices from Chainlink price feeds through the RPC endpoint (closes #525)

CoinDesk now refuses requests without an API key, so mainnet showed no USD prices. Mainnet prices now come from Chainlink's USD price feeds, read with eth_call through the user's RPC endpoint; no other service is asked. The bundled list pairs each of 53 tokens with its feed by contract address, and ETH and WETH use ETH/USD. The popup reads the feeds of ETH and the tokens the user holds or tracks in one batched request, at most every 5 minutes. A reading older than its heartbeat plus 30 minutes, or not positive, is no price. A token with no feed shows no USD value. CoinDesk is gone.

RULES.md still names the CoinDesk price API.

Model: opus-5-5

src/popup/index.js

@@ -96,7 +96,7 @@ async function doRefreshAndRender() {
         const networkId = state.networkId;
         const wallets = structuredClone(state.wallets);
         await Promise.all([
-            refreshPrices(),
+            refreshPrices(pageClosed.signal),
             refreshBalances(
                 wallets,
                 state.rpcUrl,

src/popup/views/addressToken.js

@@ -69,7 +69,7 @@ function show() {
         // null when the scale is unknown: no quantity to show, and none to
         // price. balanceLine() states that rather than printing 0.0000.
         amount = tb ? unknownableAmount(tb.balance) : 0;
-        price = getPrice(symbol);
+        price = getPrice(tokenId);
     }
 
     currentSymbol = symbol;

src/popup/views/confirmTx.js

@@ -129,7 +129,7 @@ function renderAmount(txInfo) {
     const rawSymbol = isErc20
         ? txInfo.tokenSymbol || "?"
         : nativeCurrencyByChainId(txInfo.chainId);
-    const price = getPrice(isErc20 ? rawSymbol : "ETH", txInfo.chainId);
+    const price = getPrice(txInfo.token, txInfo.chainId);
     const amountUsd = price ? parseFloat(txInfo.amount) * price : null;
     $("confirm-amount").textContent = valueWithUsd(
         shownAmount(txInfo) + " " + displaySymbol(rawSymbol),
@@ -157,7 +157,7 @@ function renderBalance(txInfo) {
         $("confirm-balance").textContent = "unknown (" + symbol + ")";
         return;
     }
-    const price = getPrice(isErc20 ? rawSymbol : "ETH", txInfo.chainId);
+    const price = getPrice(txInfo.token, txInfo.chainId);
     const balUsd = price ? parseFloat(bal) * price : null;
     $("confirm-balance").textContent = valueWithUsd(
         truncateAmountNeverZero(bal) + " " + symbol,

src/popup/views/helpers.js

@@ -439,7 +439,7 @@ function balanceLinesForAddress(addr, trackedTokens, showZero) {
         html += balanceLine(
             t.symbol,
             bal,
-            getPrice(t.symbol),
+            getPrice(t.address),
             t.address.toLowerCase(),
         );
         seen.add(t.address.toLowerCase());
@@ -450,7 +450,7 @@ function balanceLinesForAddress(addr, trackedTokens, showZero) {
             html += balanceLine(
                 t.symbol,
                 0,
-                getPrice(t.symbol),
+                getPrice(t.address),
                 t.address.toLowerCase(),
             );
         }