fix: include timezone offset in all ISO timestamp displays

All isoDate() functions now append the local timezone offset (e.g. +02:00)
to displayed timestamps. The Uniswap deadline display now retains the UTC
'Z' suffix instead of stripping it.

Closes #116

src/popup/index.html

@@ -586,6 +586,19 @@
                     <div id="confirm-fee-amount" class="text-xs"></div>
                 </div>
                 <div id="confirm-warnings" class="mb-2 hidden"></div>
+                <div
+                    id="confirm-recipient-warning"
+                    class="mb-2"
+                    style="visibility: hidden"
+                >
+                    <div
+                        class="border border-red-500 border-dashed p-2 text-xs font-bold text-red-500"
+                    >
+                        WARNING: The recipient address has ZERO transaction
+                        history. This may indicate a fresh or unused address.
+                        Double-check the address before sending.
+                    </div>
+                </div>
                 <div
                     id="confirm-errors"
                     class="mb-2 border border-border border-dashed p-2 hidden"

src/popup/styles/main.css

@@ -19,3 +19,16 @@ body {
     width: 396px;
     overflow-x: hidden;
 }
+
+/* Copy-flash feedback: inverts colors then fades back */
+.copy-flash-active {
+    background-color: var(--color-fg) !important;
+    color: var(--color-bg) !important;
+    transition: none;
+}
+
+.copy-flash-fade {
+    transition:
+        background-color 300ms ease-out,
+        color 300ms ease-out;
+}

src/popup/views/addWallet.js

@@ -11,6 +11,25 @@ const { encryptWithPassword } = require("../../shared/vault");
 const { state, saveState } = require("../../shared/state");
 const { scanForAddresses } = require("../../shared/balances");
 
+/**
+ * Check if an address already exists in ANY wallet (hd, xprv, or key).
+ * Returns the wallet object if found, or undefined.
+ */
+function findWalletByAddress(addr) {
+    const lower = addr.toLowerCase();
+    return state.wallets.find((w) =>
+        w.addresses.some((a) => a.address.toLowerCase() === lower),
+    );
+}
+
+/**
+ * Check if an xpub already exists in any HD-type wallet (hd or xprv).
+ * Returns the wallet object if found, or undefined.
+ */
+function findWalletByXpub(xpub) {
+    return state.wallets.find((w) => w.xpub && w.xpub === xpub);
+}
+
 let currentMode = "mnemonic";
 
 const MODES = ["mnemonic", "privkey", "xprv"];
@@ -97,18 +116,18 @@ async function importMnemonic(ctx) {
     const pw = validatePassword();
     if (!pw) return;
     const { xpub, firstAddress } = hdWalletFromMnemonic(mnemonic);
-    const duplicate = state.wallets.find(
-        (w) =>
-            w.type === "hd" &&
-            w.addresses[0] &&
-            w.addresses[0].address.toLowerCase() === firstAddress.toLowerCase(),
-    );
-    if (duplicate) {
+    const xpubDup = findWalletByXpub(xpub);
+    if (xpubDup) {
         showFlash(
-            "This recovery phrase is already added (" + duplicate.name + ").",
+            "This recovery phrase is already added (" + xpubDup.name + ").",
         );
         return;
     }
+    const addrDup = findWalletByAddress(firstAddress);
+    if (addrDup) {
+        showFlash("Address already exists in wallet (" + addrDup.name + ").");
+        return;
+    }
     const encrypted = await encryptWithPassword(mnemonic, pw);
     const walletNum = state.wallets.length + 1;
     const wallet = {
@@ -162,15 +181,10 @@ async function importPrivateKey(ctx) {
     }
     const pw = validatePassword();
     if (!pw) return;
-    const duplicate = state.wallets.find(
-        (w) =>
-            w.type === "key" &&
-            w.addresses[0] &&
-            w.addresses[0].address.toLowerCase() === addr.toLowerCase(),
-    );
+    const duplicate = findWalletByAddress(addr);
     if (duplicate) {
         showFlash(
-            "This private key is already added (" + duplicate.name + ").",
+            "This address already exists in wallet (" + duplicate.name + ").",
         );
         return;
     }
@@ -208,14 +222,14 @@ async function importXprvKey(ctx) {
         return;
     }
     const { xpub, firstAddress } = result;
-    const duplicate = state.wallets.find(
-        (w) =>
-            (w.type === "hd" || w.type === "xprv") &&
-            w.addresses[0] &&
-            w.addresses[0].address.toLowerCase() === firstAddress.toLowerCase(),
-    );
-    if (duplicate) {
-        showFlash("This key is already added (" + duplicate.name + ").");
+    const xpubDup = findWalletByXpub(xpub);
+    if (xpubDup) {
+        showFlash("This key is already added (" + xpubDup.name + ").");
+        return;
+    }
+    const addrDup = findWalletByAddress(firstAddress);
+    if (addrDup) {
+        showFlash("Address already exists in wallet (" + addrDup.name + ").");
         return;
     }
     const pw = validatePassword();

src/popup/views/addressDetail.js

@@ -2,6 +2,7 @@ const {
     $,
     showView,
     showFlash,
+    flashCopyFeedback,
     balanceLinesForAddress,
     addressDotHtml,
     addressTitle,
@@ -94,6 +95,10 @@ function show() {
 function isoDate(timestamp) {
     const d = new Date(timestamp * 1000);
     const pad = (n) => String(n).padStart(2, "0");
+    const off = -d.getTimezoneOffset();
+    const sign = off >= 0 ? "+" : "-";
+    const absOff = Math.abs(off);
+    const tz = sign + pad(Math.floor(absOff / 60)) + ":" + pad(absOff % 60);
     return (
         d.getFullYear() +
         "-" +
@@ -105,7 +110,8 @@ function isoDate(timestamp) {
         ":" +
         pad(d.getMinutes()) +
         ":" +
-        pad(d.getSeconds())
+        pad(d.getSeconds()) +
+        tz
     );
 }
 
@@ -241,6 +247,7 @@ function init(_ctx) {
         if (addr) {
             navigator.clipboard.writeText(addr);
             showFlash("Copied!");
+            flashCopyFeedback($("address-full"));
         }
     });
 
@@ -358,6 +365,7 @@ function init(_ctx) {
         if (key) {
             navigator.clipboard.writeText(key);
             showFlash("Copied!");
+            flashCopyFeedback($("export-privkey-value"));
         }
     });
 
@@ -366,6 +374,7 @@ function init(_ctx) {
         if (full) {
             navigator.clipboard.writeText(full);
             showFlash("Copied!");
+            flashCopyFeedback($("export-privkey-address"));
         }
     });
 

src/popup/views/addressToken.js

@@ -5,6 +5,7 @@ const {
     $,
     showView,
     showFlash,
+    flashCopyFeedback,
     addressDotHtml,
     addressTitle,
     escapeHtml,
@@ -47,6 +48,10 @@ function etherscanAddressLink(address) {
 function isoDate(timestamp) {
     const d = new Date(timestamp * 1000);
     const pad = (n) => String(n).padStart(2, "0");
+    const off = -d.getTimezoneOffset();
+    const sign = off >= 0 ? "+" : "-";
+    const absOff = Math.abs(off);
+    const tz = sign + pad(Math.floor(absOff / 60)) + ":" + pad(absOff % 60);
     return (
         d.getFullYear() +
         "-" +
@@ -58,7 +63,8 @@ function isoDate(timestamp) {
         ":" +
         pad(d.getMinutes()) +
         ":" +
-        pad(d.getSeconds())
+        pad(d.getSeconds()) +
+        tz
     );
 }
 
@@ -317,6 +323,7 @@ function init(_ctx) {
         if (addr) {
             navigator.clipboard.writeText(addr);
             showFlash("Copied!");
+            flashCopyFeedback($("address-token-full"));
         }
     });
 
@@ -325,6 +332,7 @@ function init(_ctx) {
         if (copyEl) {
             navigator.clipboard.writeText(copyEl.dataset.copy);
             showFlash("Copied!");
+            flashCopyFeedback(copyEl);
         }
     });
 
@@ -373,6 +381,7 @@ function init(_ctx) {
             copyEl.addEventListener("click", () => {
                 navigator.clipboard.writeText(copyEl.dataset.copy);
                 showFlash("Copied!");
+                flashCopyFeedback(copyEl);
             });
         }
         updateSendBalance();

src/popup/views/confirmTx.js

@@ -15,6 +15,7 @@ const {
     hideError,
     showView,
     showFlash,
+    flashCopyFeedback,
     addressTitle,
     addressDotHtml,
     escapeHtml,
@@ -117,6 +118,7 @@ function show(txInfo) {
             copyEl.onclick = () => {
                 navigator.clipboard.writeText(copyEl.dataset.copy);
                 showFlash("Copied!");
+                flashCopyFeedback(copyEl);
             };
         }
     } else {
@@ -243,7 +245,11 @@ function show(txInfo) {
     state.viewData = { pendingTx: txInfo };
     showView("confirm-tx");
 
+    // Reset recipient warning to hidden (space always reserved, no layout shift)
+    $("confirm-recipient-warning").style.visibility = "hidden";
+
     estimateGas(txInfo);
+    checkRecipientHistory(txInfo);
 }
 
 async function estimateGas(txInfo) {
@@ -286,6 +292,26 @@ async function estimateGas(txInfo) {
     }
 }
 
+async function checkRecipientHistory(txInfo) {
+    const el = $("confirm-recipient-warning");
+    try {
+        const provider = getProvider(state.rpcUrl);
+        // Skip warning for contract addresses — they may legitimately
+        // have zero outgoing transactions (getTransactionCount returns
+        // the nonce, i.e. sent-tx count only).
+        const code = await provider.getCode(txInfo.to);
+        if (code && code !== "0x") {
+            return;
+        }
+        const txCount = await provider.getTransactionCount(txInfo.to);
+        if (txCount === 0) {
+            el.style.visibility = "visible";
+        }
+    } catch (e) {
+        log.errorf("recipient history check failed:", e.message);
+    }
+}
+
 function init(ctx) {
     $("btn-confirm-send").addEventListener("click", async () => {
         const password = $("confirm-tx-password").value;

src/popup/views/helpers.js

@@ -226,6 +226,10 @@ function formatAddressHtml(address, ensName, maxLen, title) {
 function isoDate(timestamp) {
     const d = new Date(timestamp * 1000);
     const pad = (n) => String(n).padStart(2, "0");
+    const off = -d.getTimezoneOffset();
+    const sign = off >= 0 ? "+" : "-";
+    const absOff = Math.abs(off);
+    const tz = sign + pad(Math.floor(absOff / 60)) + ":" + pad(absOff % 60);
     return (
         d.getFullYear() +
         "-" +
@@ -237,7 +241,8 @@ function isoDate(timestamp) {
         ":" +
         pad(d.getMinutes()) +
         ":" +
-        pad(d.getSeconds())
+        pad(d.getSeconds()) +
+        tz
     );
 }
 
@@ -258,12 +263,26 @@ function timeAgo(timestamp) {
     return years + " year" + (years !== 1 ? "s" : "") + " ago";
 }
 
+function flashCopyFeedback(el) {
+    if (!el) return;
+    el.classList.remove("copy-flash-fade");
+    el.classList.add("copy-flash-active");
+    setTimeout(() => {
+        el.classList.remove("copy-flash-active");
+        el.classList.add("copy-flash-fade");
+        setTimeout(() => {
+            el.classList.remove("copy-flash-fade");
+        }, 350);
+    }, 100);
+}
+
 module.exports = {
     $,
     showError,
     hideError,
     showView,
     showFlash,
+    flashCopyFeedback,
     balanceLine,
     balanceLinesForAddress,
     addressColor,

src/popup/views/home.js

@@ -2,6 +2,7 @@ const {
     $,
     showView,
     showFlash,
+    flashCopyFeedback,
     balanceLinesForAddress,
     isoDate,
     timeAgo,
@@ -85,9 +86,10 @@ function renderActiveAddress() {
         el.innerHTML =
             `<span class="underline decoration-dashed cursor-pointer" id="active-addr-copy">${dot}${escapeHtml(addr)}</span>` +
             `<a href="${link}" target="_blank" rel="noopener" class="inline-flex items-center">${EXT_ICON}</a>`;
-        $("active-addr-copy").addEventListener("click", () => {
+        $("active-addr-copy").addEventListener("click", (e) => {
             navigator.clipboard.writeText(addr);
             showFlash("Copied!");
+            flashCopyFeedback(e.currentTarget);
         });
     } else {
         el.textContent = "";

src/popup/views/receive.js

@@ -2,6 +2,7 @@ const {
     $,
     showView,
     showFlash,
+    flashCopyFeedback,
     formatAddressHtml,
     addressTitle,
 } = require("./helpers");
@@ -60,11 +61,12 @@ function show() {
 }
 
 function init(ctx) {
-    $("receive-address-block").addEventListener("click", () => {
+    $("receive-address-block").addEventListener("click", (e) => {
         const addr = $("receive-address-block").dataset.full;
         if (addr) {
             navigator.clipboard.writeText(addr);
             showFlash("Copied!");
+            flashCopyFeedback(e.currentTarget);
         }
     });
 
@@ -73,6 +75,7 @@ function init(ctx) {
         if (addr) {
             navigator.clipboard.writeText(addr);
             showFlash("Copied!");
+            flashCopyFeedback($("receive-address-block"));
         }
     });
 

src/popup/views/transactionDetail.js

@@ -5,6 +5,7 @@ const {
     $,
     showView,
     showFlash,
+    flashCopyFeedback,
     addressDotHtml,
     addressTitle,
     escapeHtml,
@@ -171,6 +172,7 @@ function render() {
             el.onclick = () => {
                 navigator.clipboard.writeText(el.dataset.copy);
                 showFlash("Copied!");
+                flashCopyFeedback(el);
             };
         });
 }
@@ -248,6 +250,7 @@ async function loadCalldata(txHash, toAddress) {
                 el.onclick = () => {
                     navigator.clipboard.writeText(el.dataset.copy);
                     showFlash("Copied!");
+                    flashCopyFeedback(el);
                 };
             });
         }

src/popup/views/txStatus.js

@@ -4,6 +4,7 @@ const {
     $,
     showView,
     showFlash,
+    flashCopyFeedback,
     addressDotHtml,
     addressTitle,
     escapeHtml,
@@ -77,6 +78,7 @@ function attachCopyHandlers(viewId) {
             el.onclick = () => {
                 navigator.clipboard.writeText(el.dataset.copy);
                 showFlash("Copied!");
+                flashCopyFeedback(el);
             };
         });
 }

src/shared/uniswap.js

@@ -487,7 +487,10 @@ function decode(data, toAddress) {
         const deadlineDate = new Date(Number(deadline) * 1000);
         details.push({
             label: "Deadline",
-            value: deadlineDate.toISOString().replace("T", " ").slice(0, 19),
+            value: deadlineDate
+                .toISOString()
+                .replace("T", " ")
+                .replace(".000Z", "Z"),
         });
 
         return {