fix: give every address a row of its own, so none wraps or is shortened (closes #380) (#381)

A stored allowedSites whose value was not a list rendered a working popup and then made every subsequent save fail silently, so the user operated a wallet that persisted nothing -- worse than a blank popup, which is at least visibly broken. fraudContracts and selectedToken had the same shape: a container floored by truthiness or not at all, while its entries were dereferenced. Entries are now floored as well as containers, following the idiom #311 established, and a failed save raises a persistent banner instead of vanishing into a swallowed rejection.

The per-field justifications that used to live in a hand-written header are replaced by a contract test that drives each field's hostile and falsy values through a real popup boot, so a claim about a field answers to the code rather than to prose. Its guarantee is stated narrowly and deliberately: no structural dereference on the code paths a wholly-corrupted profile takes, which is not every path a stored record takes. The paths it does not drive are named where the claim is made, and are tracked in #379.

README.md

@@ -800,7 +800,12 @@ discoverable.
   addresses visually, as a security feature.
 - **Tailwind CSS**: Utility-first CSS via Tailwind. No custom CSS classes for
   styling. Tailwind is configured with a minimal monochrome palette. This keeps
-  the styling co-located with the markup and eliminates CSS file management.
+  the styling co-located with the markup and eliminates CSS file management. The
+  handful of classes in `styles/main.css` are not styling: `.copy-flash-*`
+  carries the copy feedback animation, and `.am-address` carries the rule that
+  an address never wraps. Both are invariants that hold in every place they
+  appear, and spelling either out as repeated utilities is how one of those
+  places drifts away from the rest.
 - **Vanilla JS**: No framework (React, Vue, Svelte, etc.). The popup UI is small
   enough that vanilla JS with simple view switching is sufficient. A framework
   would add bundle size, build complexity, and attack surface for no benefit at
@@ -849,6 +854,12 @@ that the portions still displayed will be more than adequate for the user to
 verify addresses even in the case of address spoofing attacks. Clicking an
 address will always copy the full, untruncated value.
 
+As of the address-row layout change, no view invokes that exception: every
+address in the popup is rendered on a row of its own, wide enough for all 42
+characters, and no screen truncates one to fit. The cap is still enforced in
+`truncateMiddle()` and the 32-character floor in `renderAddressHtml()`, so the
+guarantee holds for any future caller; there simply are none today.
+
 **Specific Exception — Transaction Detail view:** The transaction detail screen
 is the authoritative record of a specific transaction and shows the exact,
 untruncated amount with all meaningful decimal places (e.g. "0.00498824598498216
@@ -1182,13 +1193,17 @@ view would leave a wallet one click from deletion.
     - Send / Receive quick-action buttons, both acting on the active address
     - ETH/USD price display
     - Wallet list: each wallet shows its name (tap to rename inline) and a "+"
-      button for HD and xprv wallets, then one block per address with "Address
-      N" (bold when active), the ENS name if resolved, the full address, an
-      `[info]` button, an `[x]` button (only on HD and xprv wallets holding more
-      than one address), the address USD total, and a balance line for ETH and
-      for each token shown for that address
+      button for HD and xprv wallets, then one block per address. The block
+      opens with a row carrying the colour dot, "Address N" (bold when active),
+      an `[info]` button and an `[x]` button (only on HD and xprv wallets
+      holding more than one address); the ENS name, if resolved, is below it;
+      then the full address on a row of its own, followed by the address USD
+      total and a balance line for ETH and for each token shown for that address
     - "Recent Transactions": up to 25 transactions merged across every address
-      of every wallet, deduplicated by hash and filtered
+      of every wallet, deduplicated by hash and filtered. Each row is three
+      lines: age and direction, then the counterparty's colour dot (with our own
+      name for it, where it is one of our addresses) and the amount, then the
+      counterparty's full address on a row of its own
     - "Add additional wallet..." link at bottom
 - **Transitions**:
     - Tap address row → sets the active address and broadcasts

TODO.md

@@ -45,6 +45,22 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-08-30: An address no longer wraps, or is shortened to fit, in any of the
+  common views ([#380](https://git.eeqj.de/sneak/AutistMask/issues/380)). The
+  wallet list was the reported case: the address shared one row with the
+  `[info]` and `[x]` controls and folded onto a second line, which turns one
+  42-character string the user is meant to compare into two shorter ones — the
+  shape an address-poisoning attack wants. The fix is layout, not CSS: every
+  address in the popup now sits alone on a full-width row, with the colour dot,
+  the wallet title, the ENS name and the explorer link moved onto a strip above
+  it, and the transaction rows carry the counterparty's whole address instead of
+  a `truncateMiddle()`d one squeezed in beside the amount. `truncateMiddle()`
+  keeps its 10-character cap and its 32-character floor moved into
+  `renderAddressHtml()`, so the guarantee outlives having no callers. The e2e
+  suite measures every rendered address in a real Chromium — whole, one line
+  box, inside its row and inside the popup — across Home, the address, token,
+  receive, send and transaction detail screens, the confirmation screen and the
+  dApp transaction prompt.
 - 2026-08-23: Both manifests declare toolbar icons, and real PNGs at
   16/32/48/128 ship inside both archives
   ([#371](https://git.eeqj.de/sneak/AutistMask/issues/371)). Neither manifest

src/popup/index.html

@@ -213,10 +213,7 @@
                 </div>
 
                 <!-- active address display -->
-                <div
-                    id="active-address-display"
-                    class="text-xs break-all mb-3"
-                ></div>
+                <div id="active-address-display" class="text-xs mb-3"></div>
 
                 <!-- quick actions for active address -->
                 <div class="flex gap-2 mb-2">
@@ -292,7 +289,7 @@
                     class="font-bold mb-1 hidden flex items-center"
                 ></div>
                 <div
-                    class="text-xs mb-1 cursor-pointer break-all"
+                    class="text-xs mb-1 cursor-pointer"
                     title="Click to copy"
                     id="address-line"
                 >
@@ -380,14 +377,14 @@
                 ></div>
                 <h2 class="font-bold mb-1">Export Private Key</h2>
                 <p class="text-xs mb-1" id="export-privkey-title"></p>
-                <p class="text-xs mb-3">
+                <div class="text-xs mb-3">
                     <span id="export-privkey-dot"></span>
                     <span
                         id="export-privkey-address"
                         class="cursor-pointer"
                         title="Click to copy"
                     ></span>
-                </p>
+                </div>
                 <p class="text-xs mb-3 text-muted">
                     Warning: anyone with this private key can access and
                     transfer all funds from this address. Never share it.
@@ -440,7 +437,7 @@
                 </div>
 
                 <div
-                    class="text-xs mb-1 cursor-pointer break-all"
+                    class="text-xs mb-1 cursor-pointer"
                     title="Click to copy"
                     id="address-token-line"
                 >
@@ -573,19 +570,16 @@
                 <!-- ERC-20 token contract (hidden for ETH) -->
                 <div id="confirm-token-section" class="mb-3 hidden">
                     <div class="text-xs text-muted mb-1">Token contract</div>
-                    <div
-                        id="confirm-token-contract"
-                        class="text-xs break-all"
-                    ></div>
+                    <div id="confirm-token-contract" class="text-xs"></div>
                 </div>
 
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">From</div>
-                    <div id="confirm-from" class="text-xs break-all"></div>
+                    <div id="confirm-from" class="text-xs"></div>
                 </div>
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">To</div>
-                    <div id="confirm-to" class="text-xs break-all"></div>
+                    <div id="confirm-to" class="text-xs"></div>
                     <div
                         id="confirm-to-ens"
                         class="text-xs text-muted hidden"
@@ -728,7 +722,7 @@
                 </div>
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">To</div>
-                    <div id="wait-tx-to" class="text-xs break-all"></div>
+                    <div id="wait-tx-to" class="text-xs"></div>
                 </div>
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">Transaction hash</div>
@@ -747,7 +741,7 @@
                 </div>
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">To</div>
-                    <div id="success-tx-to" class="text-xs break-all"></div>
+                    <div id="success-tx-to" class="text-xs"></div>
                 </div>
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">Block</div>
@@ -774,7 +768,7 @@
                 </div>
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">To</div>
-                    <div id="error-tx-to" class="text-xs break-all"></div>
+                    <div id="error-tx-to" class="text-xs"></div>
                 </div>
                 <div class="mb-3">
                     <div
@@ -811,9 +805,9 @@
                     <canvas id="receive-qr"></canvas>
                 </div>
                 <div
-                    class="border border-border p-2 break-all mb-3 text-xs cursor-pointer"
+                    class="border border-border p-2 mb-3 text-xs cursor-pointer"
                 >
-                    <span id="receive-address-block" class="select-all"></span>
+                    <div id="receive-address-block" class="select-all"></div>
                     <span id="receive-etherscan-link"></span>
                 </div>
                 <button
@@ -1239,7 +1233,7 @@
                 </p>
                 <div
                     id="delete-address-value"
-                    class="text-xs mb-2 break-all min-h-[1rem]"
+                    class="text-xs mb-2 min-h-[1rem]"
                 ></div>
                 <div
                     class="text-xs mb-2 border border-border border-dashed p-2"
@@ -1429,14 +1423,11 @@
                     </div>
                     <div class="mb-2">
                         <div class="text-xs text-muted mb-1">From</div>
-                        <div
-                            id="tx-detail-from"
-                            class="text-xs break-all"
-                        ></div>
+                        <div id="tx-detail-from" class="text-xs"></div>
                     </div>
                     <div class="mb-2">
                         <div class="text-xs text-muted mb-1">To</div>
-                        <div id="tx-detail-to" class="text-xs break-all"></div>
+                        <div id="tx-detail-to" class="text-xs"></div>
                     </div>
                 </div>
 
@@ -1473,7 +1464,7 @@
                         </div>
                         <div
                             id="tx-detail-token-contract"
-                            class="text-xs break-all"
+                            class="text-xs"
                         ></div>
                     </div>
                 </div>
@@ -1567,11 +1558,11 @@
 
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">From</div>
-                    <div id="approve-tx-from" class="text-xs break-all"></div>
+                    <div id="approve-tx-from" class="text-xs"></div>
                 </div>
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">Contract</div>
-                    <div id="approve-tx-to" class="text-xs break-all"></div>
+                    <div id="approve-tx-to" class="text-xs"></div>
                 </div>
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">Value</div>
@@ -1673,7 +1664,7 @@
 
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">From</div>
-                    <div id="approve-sign-from" class="text-xs break-all"></div>
+                    <div id="approve-sign-from" class="text-xs"></div>
                 </div>
 
                 <div class="mb-3">

src/popup/styles/main.css

@@ -44,3 +44,23 @@ body {
         background-color 225ms ease-out,
         color 225ms ease-out;
 }
+
+/* An address is one atomic string, so it gets a row of its own and never
+ * breaks across lines. A wrapped address reads as two shorter strings, and
+ * two shorter strings are exactly what an address-poisoning attack needs
+ * the user to compare instead of the whole thing. Every view that shows an
+ * address puts it in one of these, alone: the colour dot, the wallet title,
+ * the ENS name and the explorer link all live on their own line above, so
+ * nothing competes with the 42 characters for width.
+ *
+ * overflow-x is the escape hatch, not the mechanism. The row is wide enough
+ * for a full address at every nesting depth the popup uses; if that ever
+ * stops being true — a font with wider glyphs, a browser zoom — the row
+ * scrolls and the user can still reach the last character, rather than the
+ * tail being clipped away by #app's overflow-x-hidden with nothing to say
+ * it happened. tests/e2e asserts the scroll is never actually needed. */
+.am-address {
+    display: block;
+    white-space: nowrap;
+    overflow-x: auto;
+}

src/popup/views/addressDetail.js

@@ -7,7 +7,6 @@ const {
     addressTitle,
     escapeHtml,
     displaySymbol,
-    truncateMiddle,
     renderAddressHtml,
     attachCopyHandlers,
     goBack,
@@ -229,10 +228,12 @@ function renderTransactions(txs) {
         const amountStr = tx.value
             ? escapeHtml(tx.value + " " + sym)
             : escapeHtml(sym);
-        const maxAddr = Math.max(32, 36 - Math.max(0, amountStr.length - 10));
-        const displayAddr =
-            title || ensName || truncateMiddle(counterparty, maxAddr);
-        const addrStr = escapeHtml(displayAddr);
+        // The counterparty used to be squeezed in beside the amount and
+        // truncated to whatever was left over. It gets its own row now and
+        // is shown whole; the title or ENS name, where there is one, names
+        // it on the line above rather than replacing it.
+        const nameStr = escapeHtml(title || ensName || "");
+        const addrStr = escapeHtml(counterparty);
         const dot = addressDotHtml(counterparty);
         const err = tx.isError ? " (failed)" : "";
         const opacity = tx.isError ? " opacity:0.5;" : "";
@@ -240,7 +241,8 @@ function renderTransactions(txs) {
         const iso = escapeHtml(isoDate(tx.timestamp));
         html += `<div class="tx-row py-2 border-b border-border-light text-xs cursor-pointer hover:bg-hover" data-tx="${i}" style="${opacity}">`;
         html += `<div class="flex justify-between"><span class="text-muted" title="${iso}">${ago}</span><span>${dirLabel}${err}</span></div>`;
-        html += `<div class="flex justify-between"><span class="flex items-center">${dot}${addrStr}</span><span>${amountStr}</span></div>`;
+        html += `<div class="flex justify-between"><span class="flex items-center">${dot}${nameStr}</span><span>${amountStr}</span></div>`;
+        html += `<div class="am-address">${addrStr}</div>`;
         html += `</div>`;
         i++;
     }

src/popup/views/addressToken.js

@@ -10,7 +10,6 @@ const {
     addressTitle,
     escapeHtml,
     displaySymbol,
-    truncateMiddle,
     balanceLine,
     unknownableAmount,
     renderAddressHtml,
@@ -305,10 +304,12 @@ function renderTransactions(txs) {
         const amountStr = tx.value
             ? escapeHtml(tx.value + " " + sym)
             : escapeHtml(sym);
-        const maxAddr = Math.max(32, 36 - Math.max(0, amountStr.length - 10));
-        const displayAddr =
-            title || ensName || truncateMiddle(counterparty, maxAddr);
-        const addrStr = escapeHtml(displayAddr);
+        // The counterparty used to be squeezed in beside the amount and
+        // truncated to whatever was left over. It gets its own row now and
+        // is shown whole; the title or ENS name, where there is one, names
+        // it on the line above rather than replacing it.
+        const nameStr = escapeHtml(title || ensName || "");
+        const addrStr = escapeHtml(counterparty);
         const dot = addressDotHtml(counterparty);
         const err = tx.isError ? " (failed)" : "";
         const opacity = tx.isError ? " opacity:0.5;" : "";
@@ -316,7 +317,8 @@ function renderTransactions(txs) {
         const iso = escapeHtml(isoDate(tx.timestamp));
         html += `<div class="tx-row py-2 border-b border-border-light text-xs cursor-pointer hover:bg-hover" data-tx="${i}" style="${opacity}">`;
         html += `<div class="flex justify-between"><span class="text-muted" title="${iso}">${ago}</span><span>${dirLabel}${err}</span></div>`;
-        html += `<div class="flex justify-between"><span class="flex items-center">${dot}${addrStr}</span><span>${amountStr}</span></div>`;
+        html += `<div class="flex justify-between"><span class="flex items-center">${dot}${nameStr}</span><span>${amountStr}</span></div>`;
+        html += `<div class="am-address">${addrStr}</div>`;
         html += `</div>`;
         i++;
     }

src/popup/views/helpers.js

@@ -331,6 +331,12 @@ function addressHoldsFunds(addr) {
     return false;
 }
 
+// The fewest characters of an address any caller may ask to display. The
+// 10-character cap inside truncateMiddle() is the other half of the same
+// guarantee; this is the half that used to be spelled out at each call
+// site, and is now enforced once in renderAddressHtml().
+const ADDRESS_MIN_DISPLAY_LEN = 32;
+
 // Truncate the middle of a string, replacing removed characters with "…".
 // Safety: refuses to truncate more than 10 characters, which is the maximum
 // that still prevents address spoofing attacks (see Display Consistency in
@@ -518,17 +524,29 @@ function attachCopyHandlers(container) {
 
 // Unified address rendering.
 //
-// Produces consistent HTML for any Ethereum address:
-//   • Color dot
-//   • Optional title (e.g. "Wallet 1 — Address 2") shown bold above address
-//   • Optional ENS name shown bold above address
-//   • Full address (or truncated via maxLen) with dashed-underline click-to-copy
-//   • Etherscan external link icon
+// Two stacked rows, in this order:
+//   1. Identity strip — colour dot, optional title (e.g. "Wallet 1 —
+//      Address 2") and the explorer link icon. Optional ENS name below it.
+//   2. The address itself, alone on a full-width row that never wraps
+//      (see .am-address in styles/main.css).
+//
+// The split is the point. Everything used to sit on one line: dot, address
+// and link together, with `break-all` to let the address fold when the line
+// ran out. In the wallet list, where the row also carried [info] and [x],
+// it ran out every time — the bug in #380 — and a folded address is a
+// spoofing hazard, not a cosmetic one. Nothing shares the address's row
+// now, so all 42 characters fit at every nesting depth the popup uses and
+// nothing has to be dropped or folded to make room.
 //
 // Options object:
 //   title    — wallet title string (from addressTitle)
 //   ensName  — ENS name string
-//   maxLen   — if set, truncate address display (min 32 chars enforced)
+//   maxLen   — if set, truncate address display. Floored at 32 characters
+//              here rather than by the caller: no view passes it any more
+//              (every address row is wide enough for all 42 characters),
+//              so a floor that lived in the callers would have gone away
+//              with them, and the "at least 32 characters" guarantee has
+//              to survive having no current callers to be a guarantee.
 //   noLink   — if true, omit etherscan link
 //
 // After inserting the returned HTML into the DOM, call
@@ -536,22 +554,22 @@ function attachCopyHandlers(container) {
 function renderAddressHtml(address, opts) {
     const { title, ensName, maxLen, noLink } = opts || {};
     const dot = addressDotHtml(address);
-    const displayAddr = maxLen ? truncateMiddle(address, maxLen) : address;
+    const displayAddr = maxLen
+        ? truncateMiddle(address, Math.max(ADDRESS_MIN_DISPLAY_LEN, maxLen))
+        : address;
     const link = etherscanAddressUrl(address);
     const extLink = noLink ? "" : etherscanLinkHtml(link);
 
     let html = "";
+    html += `<div class="flex items-center">${dot}`;
     if (title) {
-        html += `<div class="flex items-center font-bold">${dot}${escapeHtml(title)}</div>`;
+        html += `<span class="font-bold">${escapeHtml(title)}</span>`;
     }
+    html += `${extLink}</div>`;
     if (ensName) {
-        html += `<div class="flex items-center font-bold">${title ? "" : dot}${escapeHtml(ensName)}</div>`;
-    }
-    if (title || ensName) {
-        html += `<div class="flex items-center">${copyableHtml(displayAddr, "break-all")}${extLink}</div>`;
-    } else {
-        html += `<div class="flex items-center">${dot}${copyableHtml(displayAddr, "break-all")}${extLink}</div>`;
+        html += `<div class="font-bold">${escapeHtml(ensName)}</div>`;
     }
+    html += `<div class="am-address">${copyableHtml(displayAddr)}</div>`;
     return html;
 }
 

src/popup/views/home.js

@@ -9,7 +9,6 @@ const {
     addressTitle,
     escapeHtml,
     displaySymbol,
-    truncateMiddle,
     renderAddressHtml,
     attachCopyHandlers,
     pushCurrentView,
@@ -117,10 +116,13 @@ function renderHomeTxList(ctx) {
         const amountStr = tx.value
             ? escapeHtml(tx.value + " " + sym)
             : escapeHtml(sym);
+        // The counterparty used to be squeezed in beside the amount and
+        // truncated to whatever was left over. It gets its own row now and
+        // is shown whole; the title, when it is one of our own addresses,
+        // names it on the line above rather than replacing it.
         const title = addressTitle(counterparty, state.wallets);
-        const maxAddr = Math.max(32, 36 - Math.max(0, amountStr.length - 10));
-        const displayAddr = title || truncateMiddle(counterparty, maxAddr);
-        const addrStr = escapeHtml(displayAddr);
+        const titleStr = title ? escapeHtml(title) : "";
+        const addrStr = escapeHtml(counterparty);
         const dot = addressDotHtml(counterparty);
         const err = tx.isError ? " (failed)" : "";
         const opacity = tx.isError ? " opacity:0.5;" : "";
@@ -128,7 +130,8 @@ function renderHomeTxList(ctx) {
         const iso = escapeHtml(isoDate(tx.timestamp));
         html += `<div class="home-tx-row py-2 border-b border-border-light text-xs cursor-pointer hover:bg-hover" data-tx="${i}" style="${opacity}">`;
         html += `<div class="flex justify-between"><span class="text-muted" title="${iso}">${ago}</span><span>${dirLabel}${err}</span></div>`;
-        html += `<div class="flex justify-between"><span class="flex items-center">${dot}${addrStr}</span><span>${amountStr}</span></div>`;
+        html += `<div class="flex justify-between"><span class="flex items-center">${dot}${titleStr}</span><span>${amountStr}</span></div>`;
+        html += `<div class="am-address">${addrStr}</div>`;
         html += `</div>`;
         i++;
     }
@@ -252,17 +255,22 @@ function walletListHtml() {
                 : "";
             const dot = addressDotHtml(addr.address);
             const titleBold = isActive ? "font-bold" : "";
-            html += `<div class="text-xs ${titleBold}">Address ${ai + 1}</div>`;
+            // [info] and [x] ride on the "Address N" line, which was empty
+            // to its right, so the address below gets the row to itself.
+            // They used to sit beside the address and take about a third of
+            // the width off it, which is what made a 42-character address
+            // fold onto a second line here and nowhere else (#380).
+            html += `<div class="flex text-xs items-center justify-between">`;
+            html += `<span class="flex items-center ${titleBold}">${dot}Address ${ai + 1}</span>`;
+            html += `<span class="flex-shrink-0 ml-1">${infoBtn}${removeBtn}</span>`;
+            html += `</div>`;
             if (addr.ensName) {
                 // An ENS reverse record is whatever the name owner set it
                 // to; renderAddressHtml() escapes its own copy of this and
                 // this list was the one that did not.
-                html += `<div class="text-xs font-bold flex items-center">${dot}${escapeHtml(addr.ensName)}</div>`;
+                html += `<div class="text-xs font-bold">${escapeHtml(addr.ensName)}</div>`;
             }
-            html += `<div class="flex text-xs items-center justify-between">`;
-            html += `<span class="flex items-center break-all">${addr.ensName ? "" : dot}${escapeHtml(addr.address)}</span>`;
-            html += `<span class="flex-shrink-0 ml-1">${infoBtn}${removeBtn}</span>`;
-            html += `</div>`;
+            html += `<div class="am-address text-xs">${escapeHtml(addr.address)}</div>`;
             const addrTotal = formatAddressTotal(getAddressValue(addr));
             html += `<div class="text-xs text-muted text-right min-h-[1rem]">${addrTotal || "&nbsp;"}</div>`;
             html += balanceLinesForAddress(

src/popup/views/transactionDetail.js

@@ -137,10 +137,16 @@ function render() {
         if (tx.contractAddress) {
             const dot = addressDotHtml(tx.contractAddress);
             const link = explorerUrl("token", tx.contractAddress);
+            // Hand-rolled rather than renderAddressHtml() because the
+            // link goes to the explorer's /token/ page, not /address/.
+            // Same two-row shape though: dot and link on the strip, the
+            // contract address alone on the row below it.
             tokenContractEl.innerHTML =
                 `<div class="flex items-center">${dot}` +
-                copyableHtml(tx.contractAddress, "break-all") +
                 etherscanLinkHtml(link) +
+                `</div>` +
+                `<div class="am-address">` +
+                copyableHtml(tx.contractAddress) +
                 `</div>`;
             tokenContractSection.classList.remove("hidden");
         } else {

tests/e2e/run.js

@@ -1525,6 +1525,7 @@ async function goToConfirm(page, { token, balance, amount }) {
     await page.fill("#send-amount", amount);
     await page.click("#btn-send-review");
     await visible(page, "#view-confirm-tx");
+    await assertAddressesFit(page, "the confirmation screen");
 }
 
 // A balance as the main view renders it: balanceLinesForAddress() writes
@@ -3262,6 +3263,8 @@ test("eth_sendTransaction signs the approved transaction and broadcasts it (#183
             JSON.stringify(screen.data),
     );
 
+    await assertAddressesFit(popup, "the dApp transaction prompt");
+
     const broadcastBefore = env.routeOpts.broadcastTransactions.length;
     await popup.fill("#approve-tx-password", PASSWORD);
     await popup.click("#btn-approve-tx");
@@ -3425,6 +3428,206 @@ test("the password never crossed either boundary in this section (#183)", async
     await env.dapp.close();
 });
 
+// ------------------------------------------- address layout (#380)
+//
+// "addresses should never wrap in the common views. this doesn't mean to
+// just change the css, but update the layout itself so the untruncated
+// addresses are shown in full and don't mess up the layout."
+//
+// Every one of these questions is about glyph advances and the width of
+// the box an address landed in, and nothing in the markup answers any of
+// them: a row can hold `white-space: nowrap` and still be too narrow, and
+// the popup's own `overflow-x-hidden` would then hide the evidence by
+// clipping the tail. So they are measured in a real Chromium, on the real
+// rendered views, one assertion per property #380 names:
+//
+//   - the whole address is there (42 characters, no ellipsis)
+//   - it occupies exactly one line box
+//   - it fits its row, so the overflow-x escape hatch never engages
+//   - its row ends inside the popup's content box
+//   - and the document itself does not scroll sideways
+//
+// The narrowest containers the popup has are covered here — the
+// transaction detail wells (`bg-well p-3 mx-1`) and the token contract
+// well — so the wider ones cannot fail while these pass.
+
+// Everything on screen that carries an address, measured in one pass.
+// Views other than the current one are display:none and measure zero, so
+// filtering on width leaves exactly what a user can see right now.
+function addressRowReport(page) {
+    return page.evaluate(() => {
+        const app = document.getElementById("app");
+        const appRight = app.getBoundingClientRect().right;
+        const rows = [];
+        for (const el of document.querySelectorAll(".am-address")) {
+            const box = el.getBoundingClientRect();
+            if (box.width === 0) continue;
+            // Line boxes are counted off the inline content, because the
+            // element's own rect is one box whether the text inside it
+            // wrapped or not. A Range yields a rect per contained node as
+            // well as per line, so it is the distinct tops that count:
+            // a copyable span and the text inside it share one.
+            const range = document.createRange();
+            range.selectNodeContents(el);
+            const tops = new Set(
+                Array.from(range.getClientRects()).map((r) =>
+                    Math.round(r.top),
+                ),
+            );
+            rows.push({
+                text: el.innerText.trim(),
+                lineBoxes: tops.size,
+                overflow: el.scrollWidth - el.clientWidth,
+                overhang: Math.round(box.right - appRight),
+            });
+        }
+        return {
+            rows,
+            pageOverflow:
+                document.documentElement.scrollWidth -
+                document.documentElement.clientWidth,
+        };
+    });
+}
+
+async function assertAddressesFit(page, where) {
+    const report = await addressRowReport(page);
+    assert(
+        report.rows.length > 0,
+        where + ": no address rows were rendered, so nothing was measured",
+    );
+    for (const row of report.rows) {
+        assert(
+            /^0x[0-9a-fA-F]{40}$/.test(row.text),
+            where +
+                ": the address is not shown whole: " +
+                JSON.stringify(row.text),
+        );
+        assert(
+            row.lineBoxes === 1,
+            where +
+                ": " +
+                row.text +
+                " wrapped onto " +
+                row.lineBoxes +
+                " lines",
+        );
+        assert(
+            row.overflow <= 1,
+            where +
+                ": " +
+                row.text +
+                " is " +
+                row.overflow +
+                "px wider than the row holding it",
+        );
+        assert(
+            row.overhang <= 1,
+            where +
+                ": " +
+                row.text +
+                " reaches " +
+                row.overhang +
+                "px past the popup's content box",
+        );
+    }
+    assert(
+        report.pageOverflow <= 0,
+        where + ": the popup scrolls sideways by " + report.pageOverflow + "px",
+    );
+    return report.rows.length;
+}
+
+// Back to Home from wherever the suite above finished, without assuming
+// which screen that was. Every screen the popup can rest on has a Back
+// button, and Home has none, so unwinding until Home shows is the one
+// route that does not depend on the order of the tests before this point.
+async function unwindToHome(page) {
+    for (let i = 0; i < 12; i++) {
+        if (await page.isVisible("#view-main")) return;
+        const back = page
+            .locator(".view:not(.hidden) button", { hasText: "Back" })
+            .first();
+        if ((await back.count()) === 0) break;
+        await back.click();
+        await page.waitForTimeout(150);
+    }
+    await visible(page, "#view-main");
+}
+
+// The reproduction from the issue: a wallet holding more than one address.
+// Every address in the list is a full 42 characters competing with the
+// [info] and [x] controls for one row's width, which is the state the
+// wallet view was reported wrapping in.
+test("a wallet with two addresses lists both in full, unwrapped (#380)", async (env) => {
+    await unwindToHome(env.page);
+
+    const before = await env.page
+        .locator("#wallet-list .btn-addr-info")
+        .count();
+    await env.page.locator("#wallet-list .btn-add-address").first().click();
+    await env.page.waitForFunction(
+        (n) =>
+            document.querySelectorAll("#wallet-list .btn-addr-info").length > n,
+        before,
+        { timeout: 60000 },
+    );
+
+    const shown = await assertAddressesFit(env.page, "the wallet list");
+    assert(
+        shown >= before + 1,
+        "the wallet list measured " +
+            shown +
+            " addresses, fewer than the " +
+            (before + 1) +
+            " it now holds",
+    );
+
+    // The [x] control only exists on a wallet holding more than one
+    // address, so its presence is also the proof the second one landed.
+    const removable = await env.page
+        .locator("#wallet-list .btn-remove-address")
+        .count();
+    assert(removable > 0, "the second address did not reach the wallet list");
+});
+
+test("every common view shows its addresses in full on one line (#380)", async (env) => {
+    await unwindToHome(env.page);
+    await assertAddressesFit(env.page, "Home");
+
+    await env.page.locator("#wallet-list .btn-addr-info").first().click();
+    await visible(env.page, "#view-address");
+    await visible(env.page, "#tx-list .tx-row");
+    await assertAddressesFit(env.page, "the address screen");
+
+    await env.page.click("#btn-receive");
+    await visible(env.page, "#view-receive");
+    await assertAddressesFit(env.page, "the receive screen");
+    await env.page.click("#btn-receive-back");
+    await visible(env.page, "#view-address");
+
+    await env.page.click("#btn-send");
+    await visible(env.page, "#view-send");
+    await assertAddressesFit(env.page, "the send screen");
+    await env.page.click("#btn-send-back");
+    await visible(env.page, "#view-address");
+
+    // The transaction detail screen carries the narrowest address rows in
+    // the popup: its fields sit inside a well that takes another 24px of
+    // padding and 8px of margin off the content width, and the token
+    // contract row there is narrower still.
+    await env.page.locator("#address-balances .balance-row").first().click();
+    await visible(env.page, "#view-address-token");
+    await assertAddressesFit(env.page, "the token screen");
+    await env.page.click("#btn-address-token-back");
+    await visible(env.page, "#view-address");
+
+    await env.page.locator("#tx-list .tx-row").first().click();
+    await visible(env.page, "#view-transaction");
+    await visible(env.page, "#tx-detail-token-contract-section");
+    await assertAddressesFit(env.page, "the transaction detail screen");
+});
+
 // ---------------------------------------------------------------- runner
 
 async function main() {