fix: show balances and fees below 0.000001 as nonzero on the send screens (closes #343)

The stored ETH and token balances and the send-confirm screen's fee were each
cut to six decimal places, so a value below 0.000001 read as zero. Balances are
now stored exactly, whatever decimals a token declares; the balance check reads
a token balance to its first 18 places, the most an amount can have. A token
holding below 0.000001 is still left off the lists as dust, except for a token
the user tracks. The send and send-confirm screens' balances, reserve and
insufficient-balance messages go through truncateAmountNeverZero(). The
send-confirm and approval screens both render the fee through formatFee(),
which prices the exact fee in USD. The balance lists still round with
toFixed(4).

Model: opus-5-5

src/popup/views/confirmTx.js

@@ -15,6 +15,7 @@ const {
     attachCopyHandlers,
     goBack,
     onViewLeave,
+    formatFee,
 } = require("./helpers");
 const { state } = require("../../shared/state");
 const { getSignerForAddress } = require("../../shared/wallet");
@@ -31,6 +32,9 @@ const {
     transferAmountUnits,
 } = require("../../shared/transferAmount");
 const { assertWithinCeilings } = require("../../shared/approvalVerify");
+// The balance lines, the fee reserve and the insufficient-balance messages go
+// through it, as the approval screen's amounts do.
+const { truncateAmountNeverZero } = require("../../shared/amountDisplay");
 const {
     CODES,
     FEE_PENDING,
@@ -150,11 +154,17 @@ function show(txInfo) {
         $("confirm-balance").textContent =
             bal == null
                 ? "unknown (" + symbol + ")"
-                : valueWithUsd(bal + " " + symbol, balUsd);
+                : valueWithUsd(
+                      truncateAmountNeverZero(bal) + " " + symbol,
+                      balUsd,
+                  );
     } else {
         const bal = txInfo.balance || "0";
         const balUsd = ethPrice ? parseFloat(bal) * ethPrice : null;
-        $("confirm-balance").textContent = valueWithUsd(bal + " ETH", balUsd);
+        $("confirm-balance").textContent = valueWithUsd(
+            truncateAmountNeverZero(bal) + " ETH",
+            balUsd,
+        );
     }
 
     // Check for warnings (synchronous local checks)
@@ -249,7 +259,7 @@ function renderValidation(txInfo) {
                 : "Insufficient " +
                       symbol +
                       " balance. You have " +
-                      txInfo.tokenBalance +
+                      truncateAmountNeverZero(txInfo.tokenBalance) +
                       " " +
                       symbol +
                       " but are trying to send " +
@@ -262,7 +272,7 @@ function renderValidation(txInfo) {
     if (codes.includes(CODES.INSUFFICIENT_ETH)) {
         messages.push(
             "Insufficient balance. You have " +
-                txInfo.balance +
+                truncateAmountNeverZero(txInfo.balance || "0") +
                 " ETH but are trying to send " +
                 txInfo.amount +
                 " ETH.",
@@ -305,14 +315,6 @@ function setVisible(id, visible) {
     $(id).style.visibility = visible ? "visible" : "hidden";
 }
 
-// A fee in wei as an ETH string, truncated to 6 decimal places.
-function formatFeeEth(wei) {
-    const parts = formatEther(wei).split(".");
-    const dec =
-        parts.length > 1 ? parts[1].slice(0, 6).replace(/0+$/, "") || "0" : "0";
-    return parts[0] + "." + dec + " ETH";
-}
-
 async function estimateGas(txInfo) {
     try {
         const provider = getProvider(state.rpcUrl, state.networkId);
@@ -359,26 +361,20 @@ async function estimateGas(txInfo) {
         // flight; a stale fee must not reach the screen or the balance check.
         if (pendingTx !== txInfo) return;
 
-        const ethPrice = getPrice("ETH");
-        const usd = (wei) =>
-            ethPrice ? parseFloat(formatEther(wei)) * ethPrice : null;
-
+        // The fee line goes through formatFee(), as the approval screen's
+        // does, so the same fee reads the same on both.
         if (estimateWei !== null && estimateWei < gasCostWei) {
-            $("confirm-fee-amount").textContent = valueWithUsd(
-                "~" + formatFeeEth(estimateWei),
-                usd(estimateWei),
-            );
+            $("confirm-fee-amount").textContent = "~" + formatFee(estimateWei);
             $("confirm-fee-reserve").textContent =
-                "up to " + formatFeeEth(gasCostWei) + " reserved";
+                "up to " +
+                truncateAmountNeverZero(formatEther(gasCostWei)) +
+                " ETH reserved";
             setVisible("confirm-fee-reserve", true);
         } else {
             // No spread to report: either there is no estimate, or the node
             // quotes a gas price at or above maxFeePerGas, so the expected
             // cost is not below the reserve. Show the reserve alone.
-            $("confirm-fee-amount").textContent = valueWithUsd(
-                formatFeeEth(gasCostWei),
-                usd(gasCostWei),
-            );
+            $("confirm-fee-amount").textContent = formatFee(gasCostWei);
             setVisible("confirm-fee-reserve", false);
         }
         feeStatus = FEE_KNOWN;