fix: say an unknown-scale balance the same way on Send and on confirm (closes #377)

When two addresses' explorer reports disagree on a token's decimals, the
Send screen showed the stored figure while the confirmation screen said
the balance was unknown. One function in send.js now gives both the
balance and scale, so both read `unknown (SYMBOL)`.

The confirmation screen's fee-unknown message names its cause: for an
unknown scale it says the wallet does not know the token's decimal
places and the transaction cannot be sent, instead of asking for a
retry that cannot help. Other causes keep the old sentence.

Model: opus-5-5

Dockerfile

@@ -9,9 +9,9 @@ WORKDIR /app
 ENV AUTISTMASK_LINT_NATIVE=1
 
 # script/test's default 30s bound is the host figure, against a suite that
-# runs in about 8s there. In here the same suite starts on a cold jest cache
-# and shares the runner with the rest of the build, so 30s is marginal rather
-# than a bound — it killed a healthy suite at 30.6s on a cold CI cache. 180s
+# takes 23-29s there with three jest workers. In here the same suite starts on
+# a cold jest cache and shares the runner with the rest of the build, so 30s
+# is too tight — it killed a healthy suite at 30.6s on a cold CI cache. 180s
 # still catches a hang in three minutes and cannot be tripped by a suite that
 # is merely running on contended hardware.
 ENV AUTISTMASK_TEST_TIMEOUT=180

README.md

@@ -949,6 +949,13 @@ and compare against. Reading the stored field directly instead answers `null`
 for a bundled or tracked token the explorer merely omitted, which is not a
 refusal the wallet has any reason to make.
 
+The Send screen also consults every address's explorer reports, so a contract
+two addresses report different `decimals` for has no scale there, and the stored
+balance, formatted at one of those scales, is withdrawn with it. The Send
+screen's `Current balance` and the confirmation screen's balance line then both
+read `unknown (SYMBOL)`. The balance list formats each explorer row as it is
+fetched, without that cross-address check, and shows the row's figure.
+
 **Decoded amount lines on the transaction approval screen:** the `Amount` line
 of a decoded ERC-20 call, and the `Amount` and `Min. received` lines of a
 decoded swap (see TxApproval below), do not always read as a number. They can
@@ -962,16 +969,25 @@ read:
 - `Unlimited`: on the ERC-20 `Amount` line, an `approve` of the `uint256`
   maximum, an unbounded allowance. On the swap's `Amount` line, any amount at or
   above the `uint160` maximum, whichever step set the line: a `PERMIT2_PERMIT`
-  amount at that maximum, which is an unbounded permit, or a V2 or V3 exact-in
-  or `WRAP_ETH` amount that large, which is not an allowance. The router's
-  whole-balance value, `CONTRACT_BALANCE` (`2^255`), is one such amount.
+  amount at that maximum, which is an unbounded permit, or a V2 or V3 exact-in,
+  V2 exact-out or `WRAP_ETH` amount that large, which is not an allowance. The
+  router's whole-balance value, `CONTRACT_BALANCE` (`2^255`), is one such
+  amount.
+- `Up to <amount>`: the swap's `Amount` line, when the transaction has a V2
+  exact-out step, whichever step set the line, including the `WRAP_ETH` of a
+  swap paid in ETH and a `PERMIT2_PERMIT`. The swap spends at most that figure,
+  not necessarily all of it; the wait, success and error screens show it with
+  the same words. `Unlimited` and `All available (V4 open delta)` keep their
+  wording. When a V2 exact-out step sets `Min. received`, that line shows its
+  `amountOut`, the exact amount it buys.
 - `All available (V4 open delta)`: the swap's `Amount` line, when the amount it
   shows is a V4 exact-in `amountIn` of zero. V4 reads that zero as "use the
   whole open delta", so the calldata states no quantity. The line shows the
   amount of one step that names an input token or amount: the last
   `PERMIT2_PERMIT` step if there is one, otherwise the first V2 or V3 exact-in,
-  `WRAP_ETH` or V4 swap step, a V4 swap step giving the `amountIn` of its first
-  readable exact-in action.
+  V2 exact-out, `WRAP_ETH` or V4 swap step. A V2 exact-out step gives its
+  `amountInMax`, and a V4 swap step the `amountIn` of its first readable
+  exact-in action.
 - `None (no minimum guaranteed)`: the swap's `Min. received` line, when the
   minimum it shows is zero, whether a V2, V3 or V4 swap's minimum or a
   `BALANCE_CHECK_ERC20` step's `minBalance`. Before
@@ -980,9 +996,14 @@ read:
 
 The swap's `Token In` and `Token Out` lines name a currency, not an amount; each
 reads `Unknown (not named in the calldata)` when the decoder found no token for
-that side. The token permission warning on the signature screen has its own
-amount wording, including `Unknown`; the SignApproval section below describes
-it.
+that side. An `UNWRAP_WETH` step makes `Token Out` ETH only when the output side
+is WETH, on mainnet or Sepolia, or when no step set the output side; a WETH
+`Min. received` figure then reads in ETH. Otherwise `Token Out` and
+`Min. received` keep the output side's own token and figure, whether the swap
+was paid in ETH or in a token: a V2 exact-out swap that buys USDC and then
+unwraps the WETH it did not spend shows USDC. The token permission warning on
+the signature screen has its own amount wording, including `Unknown`; the
+SignApproval section below describes it.
 
 #### Partial USD totals
 
@@ -1065,9 +1086,9 @@ claiming a symbol that belongs to the native asset and therefore has no
 legitimate contract at all (`"ETH"`). That filter is unconditional — the "Hide
 tokens with fewer than 1,000 holders" setting governs the transaction history
 and the send-screen token selector, not this list. `fetchTokenBalances()` stores
-every nonzero holding of a token it admits exactly, however small, but a holding
-below 0.000001 is left out of the balance lists, the send-screen token selector,
-the address total and the remove-address warning (`isBelowOneMillionth()` in
+every nonzero holding of a token it admits, however small, but a holding below
+0.000001 is left out of the balance lists, the send-screen token selector, the
+address total and the remove-address warning (`isBelowOneMillionth()` in
 `src/shared/amountDisplay.js`). The Send and confirmation screens show it when
 its token is the one being sent. Tracked tokens with a zero balance are listed
 as well while "Show tracked tokens with zero balance" is on.
@@ -1258,7 +1279,10 @@ view would leave a wallet one click from deletion.
       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
+      counterparty's full address on a row of its own. A contract creation has
+      no counterparty: its second line is the amount alone and its third line
+      says "This transaction creates a new contract. It has no recipient." The
+      transaction lists on AddressDetail and AddressToken draw the same rows
     - "Add additional wallet..." link at bottom
 - **Transitions**:
     - Tap address row → sets the active address and broadcasts
@@ -1392,7 +1416,9 @@ view would leave a wallet one click from deletion.
     - What to send: token dropdown (or static display with contract address when
       locked from AddressToken)
     - To: address or ENS name input, with an inline validation message
-    - Amount input with current balance display
+    - Amount input with current balance display, which reads
+      `Current balance: unknown (SYMBOL)` for a token whose scale is unknown, as
+      ConfirmTx's balance line does (see Unknown token scale)
     - "Review" button, disabled until the recipient validates
 - **Transitions**:
     - "Review" (valid inputs, ENS resolved) → **ConfirmTx**
@@ -1410,7 +1436,8 @@ view would leave a wallet one click from deletion.
     - From: blockie + color dot + full address + etherscan link + wallet title
     - To: blockie + color dot + full address + etherscan link + ENS name
     - Amount: value + symbol (USD in parentheses)
-    - Your balance: value + symbol (USD in parentheses)
+    - Your balance: value + symbol (USD in parentheses), or `unknown (SYMBOL)`
+      for a token whose scale is unknown
     - Network fee: "Estimating..." then two lines, or "Unable to estimate",
       fetched async. The first line is what the transfer is expected to cost,
       `gasLimit * gasPrice` (USD in parentheses); the second is the
@@ -1426,7 +1453,11 @@ view would leave a wallet one click from deletion.
       amount plus the fee exceeds the balance (ETH transfers), not enough ETH to
       pay the fee for the transfer (ERC-20 transfers), and the fee could not be
       estimated. The first two are mutually exclusive per transfer type, so only
-      the applicable one holds space
+      the applicable one holds space. The last names its cause: for a token
+      whose scale is unknown the fee can never be estimated, and it says the
+      wallet does not know how many decimal places the token uses and that the
+      transaction cannot be sent; for any other failure it asks the user to go
+      back and try again
     - Password: an inline field on this screen, not a modal, with its own error
       line
     - "Sign & Send" button (disabled if errors, and while the network fee
@@ -1451,7 +1482,9 @@ view would leave a wallet one click from deletion.
 - **Elements**:
     - "Transaction Broadcast" heading (no back button — tx is irreversible)
     - Amount + symbol
-    - To: color dot + full address + etherscan link
+    - To: color dot + full address + etherscan link; for a contract creation,
+      which has no recipient, "This transaction creates a new contract. It has
+      no recipient." instead
     - Transaction hash: full hash (tap to copy) + etherscan link
     - Count-up timer: "Waiting for confirmation... Ns"
 - **Behavior**: Polls `getTransactionReceipt` every 10 seconds. The wait is
@@ -1480,7 +1513,8 @@ view would leave a wallet one click from deletion.
     - Decoded action well (shown when the transaction carried recognized
       calldata; the top-level Amount and To are hidden in that case)
     - Amount + symbol
-    - To: color dot + full address + etherscan link
+    - To: color dot + full address + etherscan link, or for a contract creation
+      the same sentence as on WaitTx
     - Block number
     - Transaction hash: full hash (tap to copy) + etherscan link
     - "Done" button
@@ -1495,7 +1529,8 @@ view would leave a wallet one click from deletion.
 - **Elements**:
     - "Transaction Failed" heading
     - Amount + symbol
-    - To: color dot + full address + etherscan link
+    - To: color dot + full address + etherscan link, or for a contract creation
+      the same sentence as on WaitTx
     - Error message (dashed border box)
     - Transaction hash section (hidden if broadcast failed before getting hash):
       full hash (tap to copy) + etherscan link
@@ -1533,7 +1568,7 @@ view would leave a wallet one click from deletion.
     - From: blockie + color dot + full address (tap to copy) + etherscan link;
       ENS name if available
     - To: blockie + color dot + full address (tap to copy) + etherscan link; ENS
-      name if available
+      name if available. For a contract creation, the same sentence as on WaitTx
     - Time: ISO datetime + relative age in parentheses
     - Block: block number (tap to copy) + etherscan block link
     - Amount: value + symbol (bold)
@@ -1844,8 +1879,8 @@ view would leave a wallet one click from deletion.
     - Decoded action (if calldata is recognized): action name, token details,
       amounts, steps, deadline (see Transaction Decoding)
     - From: color dot + full address + etherscan link
-    - Contract: color dot + full address + etherscan link (or "contract
-      creation"), token symbol label if known
+    - Contract: color dot + full address + etherscan link, token symbol label if
+      known; for a contract creation, the same sentence as on WaitTx
     - Value: amount in ETH (4 decimal places, USD in parentheses)
     - Network fee (max): gas limit × fee per gas in ETH (4 decimal places, USD
       in parentheses), with the gas limit and the fee per gas in gwei below it

TODO.md

@@ -45,6 +45,62 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-10-04: A token whose scale is unknown reads the same on the Send screen
+  as on the confirmation screen
+  ([#377](https://git.eeqj.de/sneak/AutistMask/issues/377)). When two addresses'
+  explorer reports disagree on a token's `decimals`, the Send screen showed the
+  stored figure while the confirmation screen it leads to said
+  `unknown (SYMBOL)`; both now say `unknown (SYMBOL)`, from one function in
+  `src/popup/views/send.js`. The confirmation screen's fee-unknown message names
+  its cause: for an unknown scale it says the wallet does not know how many
+  decimal places the token uses and that the transaction cannot be sent, instead
+  of asking the user to go back and try again, which cannot help. For any other
+  cause it is unchanged.
+
+- 2026-10-04: A Uniswap V2 exact-out swap (Universal Router command `0x09`) is
+  decoded on the approval screen
+  ([#283](https://git.eeqj.de/sneak/AutistMask/issues/283)). `decode()` in
+  `src/shared/uniswap.js` had no arm for it, so the screen named the step and
+  showed no token or amount. The input side is the path's first token with
+  `amountInMax`, the output side the last token with `amountOut`. When the
+  transaction has such a step, the `Amount` figure reads `Up to <amount>`,
+  whichever step set it, there and on the wait, success and error screens,
+  except where it reads `Unlimited` (an unbounded `PERMIT2_PERMIT`, or any
+  amount at or above the `uint160` maximum) or `All available (V4 open delta)`.
+  In every swap, `UNWRAP_WETH` makes `Token Out` ETH only when the output side
+  is WETH, on mainnet or Sepolia, or when no step set the output side; otherwise
+  `Token Out` and `Min. received` keep the output side's own token and figure.
+  V3 exact-out (`0x01`) is still not decoded.
+
+- 2026-10-04: `make test` runs jest in three worker processes
+  ([#426](https://git.eeqj.de/sneak/AutistMask/issues/426)). The `test` and
+  `test:verbose` scripts in `package.json` ran `jest --forceExit`, which starts
+  one worker per CPU core: about 47 processes and 7-8 GiB per run on the shared
+  48-core build host. They now pass `--maxWorkers=3`, and the suite takes 23-29s
+  there: inside the 30-second cap in `script/test`, which is unchanged, but not
+  by much, because `tests/persistedFieldContract.test.js` alone takes most of it
+  ([#428](https://git.eeqj.de/sneak/AutistMask/issues/428)). One or two workers
+  went past the cap. `make check`, the pre-commit hook and `script/cibuild` all
+  run the suite through these scripts.
+
+- 2026-10-04: The error container on each dApp approval screen keeps its height
+  when an error appears
+  ([#297](https://git.eeqj.de/sneak/AutistMask/issues/297)). `#approve-tx-error`
+  and `#approve-sign-error` reserved 20px, but their border and padding took
+  10px of it, so a one-line error grew them to 26px and pushed the buttons below
+  down 6px. They now reserve 30px. A new test in `tests/e2e/run.js` shows each
+  of the six password error containers on its own screen, empty and then with an
+  error, and fails if one changes height or the element below it moves. Some of
+  the longer messages these two containers can show still take two lines.
+
+- 2026-10-04: A transaction with no `to` says "This transaction creates a new
+  contract. It has no recipient." on its recipient line and in its transaction
+  history row ([#250](https://git.eeqj.de/sneak/AutistMask/issues/250)). The
+  wait, success and error screens, the transaction detail view and the history
+  rows on Home, AddressDetail and AddressToken showed a blank address there,
+  with a colour dot whose colour was `undefined`; the approval screen showed
+  "(contract creation)". A transaction with a real `to` is unchanged.
+
 - 2026-10-04: The Send and confirmation screens no longer show an ETH balance, a
   token balance or a network fee below 0.000001 as zero
   ([#343](https://git.eeqj.de/sneak/AutistMask/issues/343)). The stored balances
@@ -62,6 +118,26 @@ but the review is broader than any of them.
   render the fee through `formatFee()` in `src/popup/views/helpers.js`, which
   prices the exact fee in USD, so the same fee reads the same on both, USD value
   included.
+
+- 2026-10-04: The flash line keeps to the one line it reserves at any message
+  length ([#252](https://git.eeqj.de/sneak/AutistMask/issues/252)). A message
+  that wrapped pushed the whole screen below it down. `#flash-msg` no longer
+  wraps: text too long for the line is cut with an ellipsis, and `showFlash()`
+  puts the whole message in the line's title. Every message is also reworded to
+  at most 50 characters so none is cut; none carries a wallet name or text from
+  a server, and the add-token screens flash a fixed line for any error other
+  than a contract that is not a token. A new test in `tests/e2e/run.js` puts a
+  message several lines long on the line and fails if the line or the screen
+  below it moves. The two approval-screen error boxes are left to
+  [#297](https://git.eeqj.de/sneak/AutistMask/issues/297).
+
+- 2026-10-04: A method the wallet does not implement is refused with EIP-1193
+  code `4200` ([#279](https://git.eeqj.de/sneak/AutistMask/issues/279)). The
+  background's `Unsupported method: <method>` error carried no code, so a site
+  probing for an optional method could not tell "not implemented" from "the call
+  failed". The message is unchanged; the background's other errors with no code
+  are untouched.
+
 - 2026-10-04: Settings lists the sites connected without "Remember", and
   removing a site there disconnects it
   ([#406](https://git.eeqj.de/sneak/AutistMask/issues/406)). Such a connection

package.json

@@ -6,8 +6,8 @@
     "license": "GPL-3.0",
     "private": true,
     "scripts": {
-        "test": "jest --forceExit",
-        "test:verbose": "jest --forceExit --verbose",
+        "test": "jest --forceExit --maxWorkers=3",
+        "test:verbose": "jest --forceExit --maxWorkers=3 --verbose",
         "build": "node build.js",
         "lint": "eslint . && prettier --check .",
         "fmt": "prettier --write .",

script/test

@@ -1,13 +1,16 @@
 #!/bin/sh
 # script/test: run the test suite.
 #
-# The timeout bounds a hung suite; it is not a performance budget. On a
-# developer host the suite finishes in about 8s and REPO_POLICIES' 30s cap is
-# the bound. Inside the image the same suite also pays a cold jest cache and
-# shares the runner with the rest of the build, which is not what that budget
-# describes, so the Dockerfile raises the bound through
-# AUTISTMASK_TEST_TIMEOUT. A cap a healthy suite can trip on a cold cache
-# produces a red that means nothing, and teaches "just run it again".
+# jest runs three worker processes (package.json), not one per CPU core: on a
+# many-core shared host one per core took gigabytes of RAM per run.
+#
+# The timeout bounds a hung suite; it is not a performance budget. On the busy
+# shared build host the suite takes 23-29s with three workers, so
+# REPO_POLICIES' 30s cap is tight there, not comfortable. Inside the image the
+# same suite also pays a cold jest cache and shares the runner with the rest of
+# the build, which is not what that budget describes, so the Dockerfile raises
+# the bound through AUTISTMASK_TEST_TIMEOUT. A cap a healthy suite can trip on a
+# cold cache produces a red that means nothing, and teaches "just run it again".
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"

src/background/index.js

@@ -932,7 +932,9 @@ async function handleRpc(method, params, origin) {
         }
     }
 
-    return { error: { message: "Unsupported method: " + method } };
+    // EIP-1193 4200 lets a site tell "this wallet does not implement that"
+    // from "that call failed", and fall back.
+    return { error: { code: 4200, message: "Unsupported method: " + method } };
 }
 
 // The body of eth_sendTransaction, from the connection check through to the

src/content/inpage.js

@@ -31,11 +31,12 @@
     // an error instead of accepting the refusal.
     //
     // Whatever code arrived is passed through verbatim rather than being
-    // matched against a list: the extension emits 4001, 4100 and 4902 today,
-    // and a code this file has never heard of is still the truth about what
-    // happened. An error reported with no code at all stays a plain Error —
-    // a ProviderRpcError whose `code` is undefined would advertise a
-    // conformance it does not have. `message` is untouched in every case.
+    // matched against a list: the extension emits codes such as 4001, 4100,
+    // 4200 and 4902, and a code this file has never heard of is still the
+    // truth about what happened. An error reported with no code at all stays
+    // a plain Error — a ProviderRpcError whose `code` is undefined would
+    // advertise a conformance it does not have. `message` is untouched in
+    // every case.
     function toPageError(error) {
         const message = (error && error.message) || "Request failed";
         if (error && error.code !== undefined && error.code !== null) {

src/popup/dustThreshold.js

@@ -19,13 +19,9 @@
 // that the user did not type — the same silent substitution the visible
 // rejection message exists to end.
 
-// Must render on ONE line of #flash-msg, whose reserved height
-// (min-h-[1.25rem]) is exactly one line at text-xs. A string long enough to
-// wrap to two lines pushes the settings view down, which the No Layout Shift
-// policy forbids. Do not lengthen this without re-running the layout test in
-// tests/e2e/run.js, which measures the flash line and goes red on a shift.
-const DUST_THRESHOLD_MESSAGE =
-    "Please enter a whole number of gwei, zero or greater.";
+// Must render on ONE line of #flash-msg; see showFlash() in
+// src/popup/views/helpers.js for how long that is.
+const DUST_THRESHOLD_MESSAGE = "Enter a whole number of gwei, zero or greater.";
 
 // Returns the threshold in gwei, or null if the input is not one.
 function parseDustThresholdGwei(raw) {

src/popup/index.html

@@ -33,7 +33,7 @@
             <!-- ============ FLASH MESSAGE AREA ============ -->
             <div
                 id="flash-msg"
-                class="text-xs text-muted min-h-[1.25rem] mb-1"
+                class="text-xs text-muted min-h-[1.25rem] mb-1 truncate"
             ></div>
 
             <!-- ============ WELCOME / FIRST USE ============ -->
@@ -698,15 +698,13 @@
                     You do not have enough ETH to pay the network fee for this
                     transfer. Please add ETH to this address and try again.
                 </div>
+                <!-- Its sentence names why the fee could not be estimated,
+                so show() in confirmTx.js sets it. -->
                 <div
                     id="confirm-fee-unknown-error"
                     class="mb-2 border border-border border-dashed p-2 text-xs"
                     style="visibility: hidden"
-                >
-                    The network fee could not be estimated, so this transaction
-                    cannot be checked against your balance. Please go back and
-                    try again.
-                </div>
+                ></div>
                 <div class="mb-2">
                     <label class="block mb-1 text-xs">Password</label>
                     <input
@@ -1633,7 +1631,7 @@
                 </div>
                 <div
                     id="approve-tx-error"
-                    class="text-xs mb-2 border border-border border-dashed p-1 min-h-[1.25rem]"
+                    class="text-xs mb-2 border border-border border-dashed p-1 min-h-[1.875rem]"
                     style="visibility: hidden"
                 ></div>
                 <div class="flex justify-between">
@@ -1710,7 +1708,7 @@
                 </div>
                 <div
                     id="approve-sign-error"
-                    class="text-xs mb-2 border border-border border-dashed p-1 min-h-[1.25rem]"
+                    class="text-xs mb-2 border border-border border-dashed p-1 min-h-[1.875rem]"
                     style="visibility: hidden"
                 ></div>
                 <div class="flex justify-between">

src/popup/views/addToken.js

@@ -28,9 +28,7 @@ function init(ctx) {
     $("btn-add-token-confirm").addEventListener("click", async () => {
         const contractAddr = $("add-token-address").value.trim();
         if (!contractAddr || !contractAddr.startsWith("0x")) {
-            showFlash(
-                "Please enter a valid contract address starting with 0x.",
-            );
+            showFlash("Enter a valid contract address starting with 0x.");
             return;
         }
         const already = state.trackedTokens.find(
@@ -71,8 +69,15 @@ function init(ctx) {
             require("./addressDetail").show();
         } catch (e) {
             const detail = e.shortMessage || e.message || String(e);
-            log.errorf("Token lookup failed for", contractAddr, detail);
-            showFlash(detail);
+            log.errorf("Adding token failed for", contractAddr, detail);
+            // lookupTokenInfo() rejects a contract with a one-line message
+            // starting "Not a valid ERC-20 token". Any other error, such as a
+            // failed save, can be far longer, so it is only logged.
+            showFlash(
+                detail.startsWith("Not a valid ERC-20 token")
+                    ? detail
+                    : "Could not add the token.",
+            );
             infoEl.textContent = "";
             infoEl.style.visibility = "hidden";
         }

src/popup/views/addWallet.js

@@ -142,15 +142,13 @@ function validatePassword() {
 async function importMnemonic(ctx) {
     const mnemonic = $("wallet-mnemonic").value.trim();
     if (!mnemonic) {
-        showFlash("Enter a recovery phrase or press the die to generate one.");
+        showFlash("Enter a recovery phrase, or press the die.");
         return;
     }
     const words = mnemonic.split(/\s+/);
     if (words.length !== 12 && words.length !== 24) {
         showFlash(
-            "Recovery phrase must be 12 or 24 words. You entered " +
-                words.length +
-                ".",
+            "Recovery phrase must be 12 or 24 words, not " + words.length + ".",
         );
         return;
     }
@@ -163,14 +161,12 @@ async function importMnemonic(ctx) {
     const { xpub, firstAddress } = hdWalletFromMnemonic(mnemonic);
     const xpubDup = findWalletByXpub(xpub);
     if (xpubDup) {
-        showFlash(
-            "This recovery phrase is already added (" + xpubDup.name + ").",
-        );
+        showFlash("This recovery phrase is already added.");
         return;
     }
     const addrDup = findWalletByAddress(firstAddress);
     if (addrDup) {
-        showFlash("Address already exists in wallet (" + addrDup.name + ").");
+        showFlash("Address already exists in a wallet.");
         return;
     }
     const encrypted = await encryptWithPassword(mnemonic, pw);
@@ -229,9 +225,7 @@ async function importPrivateKey(ctx) {
     if (!pw) return;
     const duplicate = findWalletByAddress(addr);
     if (duplicate) {
-        showFlash(
-            "This address already exists in wallet (" + duplicate.name + ").",
-        );
+        showFlash("This address already exists in a wallet.");
         return;
     }
     const encrypted = await encryptWithPassword(key, pw);
@@ -258,36 +252,29 @@ async function importXprvKey(ctx) {
         return;
     }
     if (!isValidXprv(xprv)) {
-        showFlash(
-            "That extended private key is not valid. Please check it and try again.",
-        );
+        showFlash("That extended private key is not valid.");
         return;
     }
     if (!isMasterExtendedKey(xprv)) {
-        showFlash(
-            "That is an account-level or child key, which cannot be imported. " +
-                "Please paste the master extended private key for the wallet.",
-        );
+        showFlash("Please paste the master key, not a child key.");
         return;
     }
     let result;
     try {
         result = hdWalletFromXprv(xprv);
     } catch {
-        showFlash(
-            "That extended private key is not valid. Please check it and try again.",
-        );
+        showFlash("That extended private key is not valid.");
         return;
     }
     const { xpub, firstAddress } = result;
     const xpubDup = findWalletByXpub(xpub);
     if (xpubDup) {
-        showFlash("This key is already added (" + xpubDup.name + ").");
+        showFlash("This key is already added.");
         return;
     }
     const addrDup = findWalletByAddress(firstAddress);
     if (addrDup) {
-        showFlash("Address already exists in wallet (" + addrDup.name + ").");
+        showFlash("Address already exists in a wallet.");
         return;
     }
     const pw = validatePassword();

src/popup/views/addressDetail.js

@@ -3,7 +3,7 @@ const {
     showView,
     showFlash,
     balanceLinesForAddress,
-    addressDotHtml,
+    txCounterpartyHtml,
     addressTitle,
     escapeHtml,
     displaySymbol,
@@ -233,16 +233,13 @@ function renderTransactions(txs) {
         // 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;" : "";
         const ago = escapeHtml(timeAgo(tx.timestamp));
         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">${dot}${nameStr}</span><span>${amountStr}</span></div>`;
-        html += `<div class="am-address">${addrStr}</div>`;
+        html += txCounterpartyHtml(counterparty, nameStr, amountStr);
         html += `</div>`;
         i++;
     }

src/popup/views/addressToken.js

@@ -6,7 +6,7 @@ const {
     showView,
     showFlash,
     flashCopyFeedback,
-    addressDotHtml,
+    txCounterpartyHtml,
     addressTitle,
     escapeHtml,
     displaySymbol,
@@ -309,16 +309,13 @@ function renderTransactions(txs) {
         // 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;" : "";
         const ago = escapeHtml(timeAgo(tx.timestamp));
         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">${dot}${nameStr}</span><span>${amountStr}</span></div>`;
-        html += `<div class="am-address">${addrStr}</div>`;
+        html += txCounterpartyHtml(counterparty, nameStr, amountStr);
         html += `</div>`;
         i++;
     }

src/popup/views/approval.js

@@ -1,6 +1,7 @@
 const {
     $,
     addressTitle,
+    CONTRACT_CREATION_TEXT,
     escapeHtml,
     showView,
     showError,
@@ -318,7 +319,7 @@ function showTxApproval(details) {
         toHtml += approvalAddressHtml(toAddr);
         $("approve-tx-to").innerHTML = toHtml;
     } else {
-        $("approve-tx-to").innerHTML = escapeHtml("(contract creation)");
+        $("approve-tx-to").innerHTML = escapeHtml(CONTRACT_CREATION_TEXT);
     }
 
     const ethValueFormatted = formatTxValue(

src/popup/views/confirmTx.js

@@ -198,6 +198,19 @@ function show(txInfo) {
     $("confirm-amount-fee-error").classList.toggle("hidden", isErc20);
     $("confirm-gas-error").classList.toggle("hidden", !isErc20);
 
+    // The fee-unknown message names its cause, which is also known here.
+    // Without the token's scale estimateGas() cannot encode the transfer, so
+    // the estimate fails every time and going back cannot help; any other
+    // failure may clear on a retry.
+    $("confirm-fee-unknown-error").textContent =
+        isErc20 && txInfo.tokenDecimals == null
+            ? "The network fee could not be estimated, because this wallet" +
+              " does not know how many decimal places this token uses, so" +
+              " this transaction cannot be sent."
+            : "The network fee could not be estimated, so this transaction" +
+              " cannot be checked against your balance. Please go back and" +
+              " try again.";
+
     renderValidation(txInfo);
 
     // Reset password field and error
@@ -244,7 +257,8 @@ function renderValidation(txInfo) {
     });
 
     // Messages carrying the user's own numbers are built here; the fixed
-    // sentences live in the reserved elements in index.html.
+    // sentences live in the reserved elements in index.html, except the
+    // fee-unknown one, which show() sets.
     const messages = [];
     if (codes.includes(CODES.AMOUNT_INVALID)) {
         messages.push("Please enter a valid amount to send.");

src/popup/views/helpers.js

@@ -228,15 +228,19 @@ function clearFlash() {
         flashTimer = null;
     }
     $("flash-msg").textContent = "";
+    $("flash-msg").title = "";
 }
 
+// The flash line reserves exactly one line, and a message that wrapped would
+// push the screen below it down (README, No Layout Shift). So #flash-msg never
+// wraps: text too long for the line is cut with an ellipsis, and the whole
+// message is also put in the line's title. Write messages to fit, at most 50
+// characters, so none is cut.
 function showFlash(msg, duration = 2000) {
     clearFlash();
     $("flash-msg").textContent = msg;
-    flashTimer = setTimeout(() => {
-        $("flash-msg").textContent = "";
-        flashTimer = null;
-    }, duration);
+    $("flash-msg").title = msg;
+    flashTimer = setTimeout(clearFlash, duration);
 }
 
 // A stored token balance as a number, or null when there is no number in it.
@@ -427,6 +431,29 @@ function addressTitle(address, wallets) {
     return null;
 }
 
+// What every recipient line and history row says for a transaction with no
+// `to`. Such a transaction creates a contract, so there is no address to show,
+// and a blank line on these screens reads as a rendering fault.
+const CONTRACT_CREATION_TEXT =
+    "This transaction creates a new contract. It has no recipient.";
+
+// The last two lines of a transaction history row: the counterparty's colour
+// dot and name beside the amount, then its full address. A contract creation
+// the user sent has no counterparty (its `to` is ""), so its row has the
+// amount alone and the contract creation sentence in place of the address.
+function txCounterpartyHtml(address, nameHtml, amountHtml) {
+    if (!address) {
+        return (
+            `<div class="flex justify-between"><span></span><span>${amountHtml}</span></div>` +
+            `<div>${escapeHtml(CONTRACT_CREATION_TEXT)}</div>`
+        );
+    }
+    return (
+        `<div class="flex justify-between"><span class="flex items-center">${addressDotHtml(address)}${nameHtml}</span><span>${amountHtml}</span></div>` +
+        `<div class="am-address">${escapeHtml(address)}</div>`
+    );
+}
+
 // Render an address with color dot, optional ENS name, optional title,
 // and optional truncation. Title and ENS are shown as bold labels above
 // the full address.
@@ -639,6 +666,8 @@ module.exports = {
     escapeHtml,
     displaySymbol,
     addressTitle,
+    CONTRACT_CREATION_TEXT,
+    txCounterpartyHtml,
     formatAddressHtml,
     renderAddressHtml,
     copyableHtml,

src/popup/views/home.js

@@ -6,6 +6,7 @@ const {
     isoDate,
     timeAgo,
     addressDotHtml,
+    txCounterpartyHtml,
     addressTitle,
     escapeHtml,
     displaySymbol,
@@ -122,16 +123,13 @@ function renderHomeTxList(ctx) {
         // names it on the line above rather than replacing it.
         const title = addressTitle(counterparty, state.wallets);
         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;" : "";
         const ago = escapeHtml(timeAgo(tx.timestamp));
         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">${dot}${titleStr}</span><span>${amountStr}</span></div>`;
-        html += `<div class="am-address">${addrStr}</div>`;
+        html += txCounterpartyHtml(counterparty, titleStr, amountStr);
         html += `</div>`;
         i++;
     }

src/popup/views/send.js

@@ -67,13 +67,13 @@ function validateToAddress(value) {
             if (checksummed !== v) {
                 return {
                     valid: false,
-                    error: "Address checksum is invalid. Please double-check the address.",
+                    error: "Address checksum is invalid. Check the address.",
                 };
             }
         } catch {
             return {
                 valid: false,
-                error: "Address checksum is invalid. Please double-check the address.",
+                error: "Address checksum is invalid. Check the address.",
             };
         }
     }
@@ -146,6 +146,50 @@ function renderSendTokenSelect(addr) {
     }
 }
 
+// The token balance and scale the Send screen states and hands the
+// confirmation screen, so the two screens describe the holding the same way.
+//
+// The scale is resolved the same way balances.js resolved the scale it
+// DISPLAYED this token's balance at: bundled list, then the user's tracked
+// tokens, then the explorer. The stored tokenBalances[].decimals is the
+// explorer's own answer alone, so reading it raw carries a null forward for a
+// token the wallet does know the scale of — and displayedDecimals() then throws
+// inside estimateGas(), which the confirmation screen reports as an unestimable
+// fee. Unsendable, over a scale that was never in doubt
+// (https://git.eeqj.de/sneak/AutistMask/issues/349). Still null when nothing
+// knows: no fallback.
+//
+// Resolved WITH `wallets`, which balances.js does not pass: that adds
+// explorerDecimals()'s cross-address check, so a contract two addresses report
+// different scales for answers null rather than picking one. That check has to
+// apply here, because this scale encodes the transfer — it is carried forward
+// so the transfer is encoded with the number the user read rather than with
+// whatever the contract answers at signing time (see
+// src/shared/transferAmount.js). balances.js is formatting one explorer row at
+// fetch time and cannot consult a state it is in the middle of replacing.
+//
+// The two resolutions can therefore differ, and where they do, the stored
+// `balance` is a quantity computed at a scale this screen has just declined to
+// stand behind. Stating it would leave validateTransfer() checking the amount
+// against a number the wallet does not vouch for, so it is withdrawn: unknown
+// scale means unknown balance. It is null rather than "0": both screens state
+// an unknown balance as unknown, and validateTransfer() treats it as no balance
+// to spend from, which is the fail-closed side of an amount nobody can check.
+// Only a stored quantity is withdrawn: the "0" for a token that has no row at
+// all is an absence of holdings, which is true at every scale.
+function tokenBalanceAndDecimals(addr, token) {
+    const tb = (addr.tokenBalances || []).find(
+        (t) => t.address.toLowerCase() === token.toLowerCase(),
+    );
+    const tokenDecimals = resolveTokenDecimals(token, {
+        trackedTokens: state.trackedTokens,
+        wallets: state.wallets,
+    });
+    if (!tb) return { tokenBalance: "0", tokenDecimals };
+    if (tokenDecimals === null) return { tokenBalance: null, tokenDecimals };
+    return { tokenBalance: tb.balance ?? null, tokenDecimals };
+}
+
 function updateSendBalance() {
     const addr = currentAddress();
     if (!addr) return;
@@ -162,18 +206,16 @@ function updateSendBalance() {
             truncateAmountNeverZero(addr.balance || "0") +
             " ETH";
     } else {
-        const tb = (addr.tokenBalances || []).find(
-            (t) => t.address.toLowerCase() === token.toLowerCase(),
-        );
         const symbol = resolveSymbol(
             token,
             addr.tokenBalances,
             state.trackedTokens,
         );
-        // A null balance is a holding whose scale nothing knows. Saying "0"
-        // for it would be a claim about the amount; the send itself is
+        // A null balance is a holding whose scale is unknown. Saying a figure
+        // for it would be a claim about the amount, so it reads as the
+        // confirmation screen's balance line reads it; the send itself is
         // refused later by transferAmountUnits() for the same missing scale.
-        const bal = tb ? tb.balance : "0";
+        const bal = tokenBalanceAndDecimals(addr, token).tokenBalance;
         $("send-balance").textContent =
             bal == null
                 ? "Current balance: unknown (" + symbol + ")"
@@ -224,7 +266,7 @@ function init(_ctx) {
                 const provider = getProvider(state.rpcUrl, state.networkId);
                 const resolved = await provider.resolveName(to);
                 if (!resolved) {
-                    showFlash("Could not resolve " + to);
+                    showFlash("That ENS name has no address.");
                     return;
                 }
                 resolvedTo = resolved;
@@ -240,59 +282,17 @@ function init(_ctx) {
 
         let tokenSymbol = null;
         let tokenBalance = null;
-        // The scale the amount and the balance below are rendered at, carried
-        // forward so the transfer is encoded with the number the user read
-        // rather than with whatever the contract answers at signing time. See
-        // src/shared/transferAmount.js.
         let tokenDecimals = null;
         if (token !== "ETH") {
-            const tb = (addr.tokenBalances || []).find(
-                (t) => t.address.toLowerCase() === token.toLowerCase(),
-            );
             tokenSymbol = resolveSymbol(
                 token,
                 addr.tokenBalances,
                 state.trackedTokens,
             );
-            // null carried through rather than flattened to "0": the confirm
-            // screen states an unknown balance as unknown, and
-            // validateTransfer() treats it as no balance to spend from, which
-            // is the fail-closed side of an amount nobody can check.
-            tokenBalance = tb ? (tb.balance ?? null) : "0";
-            // Resolved the same way balances.js resolved the scale it
-            // DISPLAYED this token's balance at: bundled list, then the user's
-            // tracked tokens, then the explorer. The stored
-            // tokenBalances[].decimals is the explorer's own answer alone, so
-            // reading it raw carries a null forward for a token the wallet
-            // does know the scale of — and displayedDecimals() then throws
-            // inside estimateGas(), which the confirmation screen reports as
-            // an unestimable fee. Unsendable, over a scale that was never in
-            // doubt (https://git.eeqj.de/sneak/AutistMask/issues/349).
-            // Still null when nothing knows: no fallback.
-            //
-            // Resolved WITH `wallets`, which balances.js does not pass: that
-            // adds explorerDecimals()'s cross-address check, so a contract two
-            // addresses report different scales for answers null rather than
-            // picking one. That check has to apply here, because this value
-            // encodes a transfer; balances.js is formatting one explorer row
-            // at fetch time and cannot consult a state it is in the middle of
-            // replacing.
-            tokenDecimals = resolveTokenDecimals(token, {
-                trackedTokens: state.trackedTokens,
-                wallets: state.wallets,
-            });
-            // The two resolutions can therefore differ, and where they do, the
-            // stored `balance` is a quantity computed at a scale this screen
-            // has just declined to stand behind. Stating it would leave
-            // validateTransfer() checking the amount against a number the
-            // wallet does not vouch for, and — since the unknown-balance path
-            // is gated on the balance, not on the scale — would leave the
-            // fee-estimate failure as the only thing on the confirmation
-            // screen, which says nothing about decimals. Unknown scale means
-            // unknown balance. Only a stored quantity is withdrawn: the "0"
-            // for a token that has no row at all is an absence of holdings,
-            // which is true at every scale.
-            if (tb && tokenDecimals === null) tokenBalance = null;
+            ({ tokenBalance, tokenDecimals } = tokenBalanceAndDecimals(
+                addr,
+                token,
+            ));
         }
 
         ctx.showConfirmTx({

src/popup/views/settings.js

@@ -264,18 +264,12 @@ function init(ctx) {
             const json = await resp.json();
             if (json.error) {
                 log.errorf("RPC validation error:", json.error);
-                showFlash("Endpoint returned error: " + json.error.message);
+                showFlash("Endpoint returned an error.");
                 return;
             }
             const net = currentNetwork();
             if (json.result !== net.chainId) {
-                showFlash(
-                    "Wrong network (expected " +
-                        net.name +
-                        ", got chain " +
-                        json.result +
-                        ").",
-                );
+                showFlash("Wrong network: expected " + net.name + ".");
                 return;
             }
         } catch (e) {

src/popup/views/settingsAddToken.js

@@ -115,9 +115,7 @@ function init(_ctx) {
     $("btn-settings-addtoken-manual").addEventListener("click", async () => {
         const addr = $("settings-addtoken-address").value.trim();
         if (!addr || !addr.startsWith("0x")) {
-            showFlash(
-                "Please enter a valid contract address starting with 0x.",
-            );
+            showFlash("Enter a valid contract address starting with 0x.");
             return;
         }
         if (isTracked(addr)) {
@@ -155,8 +153,15 @@ function init(_ctx) {
             ctx.doRefreshAndRender();
         } catch (e) {
             const detail = e.shortMessage || e.message || String(e);
-            log.errorf("Token lookup failed for", addr, detail);
-            showFlash(detail);
+            log.errorf("Adding token failed for", addr, detail);
+            // lookupTokenInfo() rejects a contract with a one-line message
+            // starting "Not a valid ERC-20 token". Any other error, such as a
+            // failed save, can be far longer, so it is only logged.
+            showFlash(
+                detail.startsWith("Not a valid ERC-20 token")
+                    ? detail
+                    : "Could not add the token.",
+            );
             infoEl.textContent = "";
             infoEl.style.visibility = "hidden";
         }

src/popup/views/transactionDetail.js

@@ -7,6 +7,7 @@ const {
     showFlash,
     flashCopyFeedback,
     addressTitle,
+    CONTRACT_CREATION_TEXT,
     addressDotHtml,
     escapeHtml,
     isoDate,
@@ -94,13 +95,18 @@ function render() {
     $("tx-detail-hash").innerHTML = txHashHtml(tx.hash);
 
     const fromTitle = addressTitle(tx.from, state.wallets);
-    const toTitle = addressTitle(tx.to, state.wallets);
     $("tx-detail-from").innerHTML = txAddressHtml(
         tx.from,
         tx.fromEns,
         fromTitle,
     );
-    $("tx-detail-to").innerHTML = txAddressHtml(tx.to, tx.toEns, toTitle);
+    // A contract creation has no recipient: transactions.js gives it `to: ""`.
+    if (tx.to) {
+        const toTitle = addressTitle(tx.to, state.wallets);
+        $("tx-detail-to").innerHTML = txAddressHtml(tx.to, tx.toEns, toTitle);
+    } else {
+        $("tx-detail-to").innerHTML = escapeHtml(CONTRACT_CREATION_TEXT);
+    }
 
     // Exact amount (full precision, copyable)
     const detailSym = displaySymbol(tx.symbol);

src/popup/views/txStatus.js

@@ -4,6 +4,7 @@ const {
     $,
     showView,
     addressTitle,
+    CONTRACT_CREATION_TEXT,
     escapeHtml,
     renderAddressHtml,
     attachCopyHandlers,
@@ -58,7 +59,10 @@ function endWait() {
     }
 }
 
+// A contract creation reaches these screens with `to` as "" (approval.js
+// writes `to: toAddr || ""`).
 function toAddressHtml(address) {
+    if (!address) return escapeHtml(CONTRACT_CREATION_TEXT);
     const title = addressTitle(address, state.wallets);
     return renderAddressHtml(address, { title });
 }
@@ -202,8 +206,9 @@ function restoreWait() {
     if (!info || typeof info !== "object" || Array.isArray(info)) return false;
     // A string is the whole requirement: the empty string is what a
     // contract-deployment approval persists (approval.js writes `to: toAddr
-    // || ""`), and both fields render harmlessly when empty, so refusing it
-    // would abandon a wait the live path itself created.
+    // || ""`), an empty `to` renders as a contract creation and an empty
+    // amount renders harmlessly, so refusing it would abandon a wait the live
+    // path itself created.
     if (typeof info.to !== "string") return false;
     if (typeof info.amount !== "string") return false;
     if (typeof w.broadcastTime !== "number" || !isFinite(w.broadcastTime)) {

src/shared/uniswap.js

@@ -100,6 +100,13 @@ const NO_MINIMUM = "None (no minimum guaranteed)";
 // Permit2 amounts are uint160; the maximum is Permit2's "unbounded".
 const MAX_UINT160 = BigInt("0xffffffffffffffffffffffffffffffffffffffff");
 
+// WETH, the token UNWRAP_WETH turns into ETH: on mainnet, then on Sepolia.
+// decode() is not told the network, so it takes either.
+const WETH_ADDRESSES = [
+    "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
+    "0xfff9976782d46cc05630d1f6ebab18b2324d6b14",
+];
+
 // `decimals` is null when nothing knows this token's scale. It is not
 // defaulted to 18: the swap lines land on the same approval screen as the
 // ERC-20 line, and a scale guessed there is what showed a 1,000 USDT swap as
@@ -198,11 +205,6 @@ function decodeV2SwapExactIn(input) {
 // Decode V2_SWAP_EXACT_OUT (command 0x09) input bytes.
 // ABI: (address recipient, uint256 amountOut, uint256 amountInMax,
 //        address[] path, bool payerIsUser)
-//
-// Nothing calls this: decode() has no 0x09 arm, so a V2 exact-out swap gets
-// its command name and no token or amount detail. Kept for the fix, which is
-// https://git.eeqj.de/sneak/AutistMask/issues/283.
-// eslint-disable-next-line no-unused-vars
 function decodeV2SwapExactOut(input) {
     try {
         const d = coder.decode(
@@ -447,6 +449,7 @@ function decode(data, toAddress, sources) {
         let outputToken = null;
         let minOutput = null;
         let hasUnwrapWeth = false;
+        let hasV2ExactOut = false;
         const commandNames = [];
 
         // THE INVARIANT: an amount and the token it is counted in always come
@@ -521,6 +524,16 @@ function decode(data, toAddress, sources) {
                     }
                 }
 
+                if (cmdId === 0x09) {
+                    // Buys exactly amountOut and spends at most amountInMax.
+                    hasV2ExactOut = true;
+                    const s = decodeV2SwapExactOut(inputs[i]);
+                    if (s) {
+                        setInputOnce(s.tokenIn, s.amountInMax);
+                        setOutput(s.tokenOut, s.amountOut);
+                    }
+                }
+
                 if (cmdId === 0x0b) {
                     const w = decodeWrapEth(inputs[i]);
                     if (w) {
@@ -559,12 +572,19 @@ function decode(data, toAddress, sources) {
 
         // Resolve token info. A null token on either side means the calldata
         // named no currency for it; tokenInfo() refuses rather than calling it
-        // ETH. UNWRAP_WETH is the one output that is ETH without a currency to
-        // decode, and it is answered here rather than left to that rule.
+        // ETH. UNWRAP_WETH turns WETH into ETH, so it makes the output ETH
+        // when the output side is WETH, or when no step set the output side.
+        // Any other output keeps its own token and figure: a swap that buys
+        // USDC and then unwraps the WETH it did not spend receives USDC.
+        const outputIsWeth =
+            present(outputToken) &&
+            WETH_ADDRESSES.includes(outputToken.toLowerCase());
+        const outputUnset = !present(outputToken) && !present(minOutput);
         const inInfo = tokenInfo(inputToken, sources);
-        const outInfo = hasUnwrapWeth
-            ? { symbol: "ETH", decimals: 18, address: null }
-            : tokenInfo(outputToken, sources);
+        const outInfo =
+            hasUnwrapWeth && (outputIsWeth || outputUnset)
+                ? { symbol: "ETH", decimals: 18, address: null }
+                : tokenInfo(outputToken, sources);
 
         const inSymbol = inInfo.symbol;
         const outSymbol = outInfo.symbol;
@@ -613,6 +633,17 @@ function decode(data, toAddress, sources) {
                 amount = { raw: OPEN_DELTA_AMOUNT, display: OPEN_DELTA_AMOUNT };
             } else if (inputAmount >= MAX_UINT160) {
                 amount = { raw: "Unlimited", display: "Unlimited" };
+            } else if (hasV2ExactOut) {
+                // A V2 exact-out swap spends at most this figure, whichever
+                // step set the line (its amountInMax, the WRAP_ETH of a swap
+                // paid in ETH, a permit), so it is said to be a maximum, in
+                // `raw` too: the wait, success and error screens show `raw` as
+                // the transaction's amount.
+                const most = amountText(inputAmount, inInfo);
+                amount = {
+                    raw: "Up to " + most.raw,
+                    display: "Up to " + most.display,
+                };
             } else {
                 amount = amountText(inputAmount, inInfo);
             }

src/shared/walletDefects.js

@@ -41,12 +41,10 @@ const DEFECTS = {
                 "changed or removed, and this wallet stays until you delete " +
                 "it yourself.",
         ],
-        // One sentence for the places that have room for one: the flash on a
-        // blocked Send, the inline error on the approval screens.
-        shortMessage:
-            "This wallet cannot sign, because it was imported from an " +
-            "extended private key that is not a master key. The wallet list " +
-            "explains what happened.",
+        // One line, for the flash on a blocked Send and the inline error on
+        // the approval screens. It must fit on the flash line; see showFlash()
+        // in src/popup/views/helpers.js.
+        shortMessage: "This wallet cannot sign. See the wallet list.",
     },
 };
 

tests/contractCreation.test.js

@@ -0,0 +1,315 @@
+// The recipient line of a contract creation
+// (https://git.eeqj.de/sneak/AutistMask/issues/250).
+//
+// A transaction with no `to` creates a contract. The approval screen, the
+// wait, success and error screens, the transaction detail view and the
+// transaction history rows each say so in a sentence, where they used to show
+// a blank line (an empty address, with a colour dot whose colour was
+// `undefined`) or, on the approval screen, "(contract creation)". A
+// transaction with a real `to` still shows that address.
+//
+// Driven against a minimal DOM stub in the shape
+// tests/typedDataPermit.test.js uses.
+
+jest.mock("../src/shared/log", () => ({
+    log: {
+        debugf: () => {},
+        infof: () => {},
+        warnf: () => {},
+        errorf: () => {},
+    },
+    // The transaction detail view fetches on-chain details after drawing; an
+    // answer that is not ok leaves the drawn lines as they are.
+    debugFetch: async () => ({ ok: false }),
+    setRuntimeDebug: () => {},
+    isDebug: () => false,
+}));
+
+// The wait screen polls for a receipt; this one never arrives.
+jest.mock("../src/shared/balances", () => ({
+    getProvider: () => ({ getTransactionReceipt: () => new Promise(() => {}) }),
+    refreshBalances: () => {},
+}));
+
+// The history lists ask the explorer for their transactions and resolve ENS
+// names for them; here the explorer answers with mockHistory and no name
+// resolves.
+let mockHistory = [];
+jest.mock("../src/shared/transactions", () => ({
+    ...jest.requireActual("../src/shared/transactions"),
+    fetchRecentTransactions: async () => mockHistory,
+}));
+jest.mock("../src/shared/ens", () => ({
+    ...jest.requireActual("../src/shared/ens"),
+    resolveEnsNames: async () => new Map(),
+}));
+
+globalThis.chrome = {
+    storage: { local: { get: async () => ({}), set: async () => {} } },
+};
+
+const { state } = require("../src/shared/state");
+const approval = require("../src/popup/views/approval");
+const txStatus = require("../src/popup/views/txStatus");
+const transactionDetail = require("../src/popup/views/transactionDetail");
+const home = require("../src/popup/views/home");
+const addressDetail = require("../src/popup/views/addressDetail");
+const addressToken = require("../src/popup/views/addressToken");
+
+const SENTENCE =
+    "This transaction creates a new contract. It has no recipient.";
+
+const FROM = "0x0000000000000000000000000000000000000a11";
+const RECIPIENT = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
+const TX_HASH =
+    "0x85215772ed26ea8b39c2b3b18779030487efbe0b5fd7e882592b2f62b837be84";
+// Init code for a contract creation's data.
+const INIT_CODE = "0x600160005500";
+
+function makeElement(id) {
+    const classes = new Set();
+    const el = {
+        id,
+        textContent: "",
+        value: "",
+        innerHTML: "",
+        disabled: false,
+        style: {},
+        dataset: {},
+        classList: {
+            add: (...names) => names.forEach((n) => classes.add(n)),
+            remove: (...names) => names.forEach((n) => classes.delete(n)),
+            contains: (n) => classes.has(n),
+            toggle: (n, force) => {
+                const on = force === undefined ? !classes.has(n) : force;
+                if (on) classes.add(n);
+                else classes.delete(n);
+                return on;
+            },
+        },
+        addEventListener: () => {},
+        querySelectorAll: () => [],
+        appendChild: () => {},
+    };
+    // Views reach for .parentElement to hide whole sections.
+    Object.defineProperty(el, "parentElement", {
+        get: () => node(id + "-parent"),
+    });
+    return el;
+}
+
+function makeDocument() {
+    const els = new Map();
+    return {
+        getElementById(id) {
+            // The debug banner is created on demand by helpers.js; absent
+            // is the state a non-debug, non-testnet popup is in.
+            if (id === "debug-banner") return null;
+            if (!els.has(id)) els.set(id, makeElement(id));
+            return els.get(id);
+        },
+        createElement: () => makeElement("created"),
+        body: { prepend: () => {} },
+    };
+}
+
+function node(id) {
+    return globalThis.document.getElementById(id);
+}
+
+// The line a transaction with a real `to` shows: that address, and nothing
+// left over from an empty one.
+function expectAddressLine(html) {
+    expect(html).toContain(RECIPIENT);
+    expect(html).not.toContain(SENTENCE);
+    expect(html).not.toContain("undefined");
+}
+
+beforeEach(() => {
+    globalThis.document = makeDocument();
+    globalThis.window = { location: { search: "" } };
+    state.wallets = [];
+    state.trackedTokens = [];
+    state.viewData = {};
+    state.viewStack = [];
+    state.currentView = null;
+    txStatus.init({ doRefreshAndRender: () => {} });
+});
+
+afterEach(() => {
+    txStatus.endWait();
+});
+
+// Open the transaction approval screen the way the popup does: the background
+// hands over the populated transaction and show() draws it.
+async function openTxApproval(to, data) {
+    globalThis.chrome.runtime = {
+        connect: () => ({ postMessage: () => {} }),
+        sendMessage: (msg, reply) => {
+            if (!reply) return;
+            if (msg.type !== "AUTISTMASK_GET_APPROVAL") return reply(null);
+            reply({
+                type: "tx",
+                hostname: "dapp.example",
+                isPhishingDomain: false,
+                approvedFrom: FROM,
+                approvedTx: {
+                    type: 2,
+                    from: FROM,
+                    chainId: "0x1",
+                    nonce: "0x7",
+                    gasLimit: "0x5208",
+                    maxPriorityFeePerGas: "0x3b9aca00",
+                    maxFeePerGas: "0x77359400",
+                    to,
+                    value: "0x0",
+                    data,
+                    accessList: [],
+                },
+            });
+        },
+    };
+    approval.init({});
+    await approval.show(1);
+}
+
+describe("the transaction approval screen", () => {
+    test("a contract creation says so instead of naming a contract", async () => {
+        await openTxApproval(null, INIT_CODE);
+        expect(node("approve-tx-to").innerHTML).toBe(SENTENCE);
+    });
+
+    test("a transaction with a recipient shows its address", async () => {
+        await openTxApproval(RECIPIENT, "0x");
+        expectAddressLine(node("approve-tx-to").innerHTML);
+    });
+});
+
+// approval.js carries a contract creation to these screens with `to` as "".
+describe("the wait, success and error screens", () => {
+    const creation = {
+        to: "",
+        amount: "0.0000",
+        token: "ETH",
+        tokenSymbol: null,
+    };
+    const transfer = { ...creation, to: RECIPIENT };
+
+    test("a contract creation says so on the wait screen", () => {
+        txStatus.showWait(creation, TX_HASH);
+        expect(node("wait-tx-to").innerHTML).toBe(SENTENCE);
+    });
+
+    test("a transaction with a recipient shows its address on the wait screen", () => {
+        txStatus.showWait(transfer, TX_HASH);
+        expectAddressLine(node("wait-tx-to").innerHTML);
+    });
+
+    test("a contract creation says so on the success and error screens", () => {
+        state.viewData = {
+            amount: "0.0000",
+            symbol: "ETH",
+            to: "",
+            hash: TX_HASH,
+            blockNumber: 1,
+        };
+        txStatus.renderSuccess();
+        expect(node("success-tx-to").innerHTML).toBe(SENTENCE);
+
+        txStatus.showError(creation, TX_HASH, "The transaction failed.");
+        expect(node("error-tx-to").innerHTML).toBe(SENTENCE);
+    });
+
+    test("a transaction with a recipient shows its address on the success and error screens", () => {
+        state.viewData = {
+            amount: "0.0050",
+            symbol: "ETH",
+            to: RECIPIENT,
+            hash: TX_HASH,
+            blockNumber: 1,
+        };
+        txStatus.renderSuccess();
+        expectAddressLine(node("success-tx-to").innerHTML);
+
+        txStatus.showError(transfer, TX_HASH, "The transaction failed.");
+        expectAddressLine(node("error-tx-to").innerHTML);
+    });
+});
+
+// A transaction FROM sent, as the history lists hold it. The explorer reports a
+// contract creation with no `to`, which src/shared/transactions.js turns into
+// `to: ""`.
+function historyTx(to) {
+    return {
+        hash: TX_HASH,
+        from: FROM,
+        to,
+        value: "0.0000",
+        exactValue: "0.0",
+        rawAmount: "0",
+        rawUnit: "wei",
+        symbol: "ETH",
+        timestamp: 1790000000,
+        isError: false,
+        directionLabel: "Sent",
+        direction: "sent",
+        contractAddress: null,
+    };
+}
+
+// The detail view is opened with the transaction a history row holds.
+describe("the transaction detail view", () => {
+    test("a contract creation says so", () => {
+        transactionDetail.show(historyTx(""));
+        expect(node("tx-detail-to").innerHTML).toBe(SENTENCE);
+        expect(node("tx-detail-type").textContent).toBe("Contract Creation");
+    });
+
+    test("a transaction with a recipient shows its address", () => {
+        transactionDetail.show(historyTx(RECIPIENT));
+        expectAddressLine(node("tx-detail-to").innerHTML);
+    });
+});
+
+// The same rows are drawn on Home, AddressDetail and AddressToken (for ETH).
+describe.each([
+    ["Home", "home-tx-list", () => home.render({})],
+    ["AddressDetail", "tx-list", () => addressDetail.show()],
+    ["AddressToken", "address-token-tx-list", () => addressToken.show()],
+])("the transaction history on %s", (_name, listId, open) => {
+    async function rowsFor(tx) {
+        mockHistory = [tx];
+        open();
+        // The list is drawn once the history has been fetched.
+        await new Promise((resolve) => setTimeout(resolve, 0));
+        return node(listId).innerHTML;
+    }
+
+    beforeEach(() => {
+        state.wallets = [
+            {
+                name: "Main",
+                type: "key",
+                addresses: [{ address: FROM, balance: "0.0000" }],
+            },
+        ];
+        state.selectedWallet = 0;
+        state.selectedAddress = 0;
+        state.selectedToken = "ETH";
+    });
+
+    test("a contract creation's row says so, with no colour dot and no address line", async () => {
+        const html = await rowsFor(historyTx(""));
+        expect(html).toContain(SENTENCE);
+        expect(html).not.toContain("background:");
+        expect(html).not.toContain("am-address");
+        expect(html).not.toContain("undefined");
+    });
+
+    test("a transaction with a recipient shows its colour dot and address", async () => {
+        const html = await rowsFor(historyTx(RECIPIENT));
+        expectAddressLine(html);
+        expect(html).toContain("background:#");
+        expect(html).toContain(`<div class="am-address">${RECIPIENT}</div>`);
+    });
+});

tests/dustThreshold.test.js

@@ -99,12 +99,13 @@ describe("the flash line the message is shown in", () => {
     // length, including one that wrapped to two lines and pushed the
     // settings view down 12px.
     //
-    // The assertion that actually measures — empty line vs. the message,
-    // real Chromium, documented 360x600 popup — is
-    // "a rejected dust threshold shifts no layout (#233)" in
-    // tests/e2e/run.js, run by make test-e2e. It is not in make check
-    // because REPO_POLICIES.md caps make test at 20 seconds and a browser
-    // suite does not fit; run it before changing the wording.
+    // The line cuts a message too long for it with an ellipsis (see
+    // showFlash() in src/popup/views/helpers.js). The assertions that
+    // measure that, in a real browser at the documented 360x600 popup, are
+    // "a rejected dust threshold shifts no layout (#233)" and "an over-long
+    // flash message keeps to one line (#252)" in tests/e2e/run.js, run by
+    // make test-e2e. They are not in make check because REPO_POLICIES.md
+    // caps make test at 20 seconds and a browser suite does not fit.
     test("reserves its height in the markup", () => {
         const flashLine = POPUP_HTML.match(
             /<div\s+id="flash-msg"\s+class="([^"]*)"/,

tests/e2e/run.js

@@ -1320,17 +1320,13 @@ async function waitForFilledFlashLine(page) {
 }
 
 // README, No Layout Shift: the rejection message goes into #flash-msg,
-// whose min-h-[1.25rem] reserves exactly ONE line at text-xs. Reserving
-// the space is not enough on its own — a message too long for one line
-// wraps and pushes everything below it down anyway, which is what the
-// first version of this change shipped: 75 characters, 32px, the settings
-// view and the threshold field 12px lower than with an empty line.
-//
-// So this measures rather than inspects markup. It is the only assertion
-// in the repo that can see the wording grow: the unit suite runs on the
-// node environment with no layout engine, where every height is zero (see
-// the note in tests/dustThreshold.test.js). Lengthen
-// DUST_THRESHOLD_MESSAGE past one line and this test goes red.
+// whose min-h-[1.25rem] reserves exactly ONE line at text-xs, and which
+// cuts a message too long for that line with an ellipsis rather than wrap
+// it. This shows the real message and measures that nothing moves; the
+// test after it does the same with a message several lines long. Both
+// measure rather than inspect markup: the unit suite runs on the node
+// environment with no layout engine, where every height is zero (see the
+// note in tests/dustThreshold.test.js).
 test("a rejected dust threshold shifts no layout (#233)", async (env) => {
     const page = await openPopup(env.ctx, env.popupUrl);
     try {
@@ -1377,11 +1373,11 @@ test("a rejected dust threshold shifts no layout (#233)", async (env) => {
         );
         assert(
             after.flashHeight === before.flashHeight,
-            "the message does not fit the reserved line: " +
+            "the message does not keep to the reserved line: " +
                 before.flashHeight +
                 "px empty vs " +
                 after.flashHeight +
-                "px with the message. Shorten DUST_THRESHOLD_MESSAGE",
+                "px with the message",
         );
         assert(
             after.settingsTop === before.settingsTop,
@@ -1400,6 +1396,134 @@ test("a rejected dust threshold shifts no layout (#233)", async (env) => {
     }
 });
 
+// ------------------------------------------------ the flash line (#252)
+
+// #flash-msg never wraps: a message too long for its one line is cut with an
+// ellipsis (see showFlash() in src/popup/views/helpers.js). This puts a
+// message several lines long into it and measures that the line and the
+// screen below it stay where they were.
+test("an over-long flash message keeps to one line (#252)", async (env) => {
+    const page = await openPopup(env.ctx, env.popupUrl);
+    try {
+        await page.setViewportSize(POPUP_VIEWPORT);
+        await openSettings(page);
+
+        const before = await page.evaluate(measureFlashLine);
+        const overflows = await page.evaluate(() => {
+            const line = document.getElementById("flash-msg");
+            line.textContent =
+                "This message is far too long for one line. ".repeat(5);
+            return line.scrollWidth > line.clientWidth;
+        });
+        const after = await page.evaluate(measureFlashLine);
+
+        assert(
+            after.flashHeight === before.flashHeight,
+            "the flash line is " +
+                before.flashHeight +
+                "px before and " +
+                after.flashHeight +
+                "px with an over-long message, so it wraps",
+        );
+        assert(
+            after.settingsTop === before.settingsTop,
+            "the settings view moved " +
+                (after.settingsTop - before.settingsTop) +
+                "px when the message appeared",
+        );
+        assert(
+            after.fieldTop === before.fieldTop,
+            "the dust threshold field moved " +
+                (after.fieldTop - before.fieldTop) +
+                "px when the message appeared",
+        );
+        // Checked last: a line that wraps does not run past its right edge,
+        // so this only shows the message really was cut once nothing moved.
+        assert(
+            overflows,
+            "the message fits on the line, so it proves nothing: " +
+                JSON.stringify(after.text),
+        );
+    } finally {
+        await page.close();
+    }
+});
+
+// --------------------------------------- password error containers (#297)
+
+// Every screen that asks for a password reserves room for one line of error.
+// The two on the dApp approval screens also have a border and padding, which
+// that reserved height has to cover too.
+const PASSWORD_ERROR_CONTAINERS = [
+    "approve-tx-error",
+    "approve-sign-error",
+    "export-privkey-flash",
+    "show-phrase-flash",
+    "delete-wallet-flash",
+    "confirm-tx-password-error",
+];
+
+// Shows only the screen holding the container, then measures the container
+// and the element below it empty and again filled the way showError() in
+// src/popup/views/helpers.js fills it. Runs in the page.
+function measurePasswordError(id) {
+    const container = document.getElementById(id);
+    const screen = container.closest(".view");
+    for (const view of document.querySelectorAll(".view")) {
+        view.classList.toggle("hidden", view !== screen);
+    }
+    const below = container.nextElementSibling;
+    const measure = () => ({
+        height: container.getBoundingClientRect().height,
+        belowTop: below.getBoundingClientRect().top + window.scrollY,
+        belowHeight: below.getBoundingClientRect().height,
+    });
+    const empty = measure();
+    container.textContent = "Please enter your password.";
+    container.style.visibility = "visible";
+    const filled = measure();
+    container.textContent = "";
+    container.style.visibility = "hidden";
+    return { empty, filled };
+}
+
+test("a password error moves nothing on any screen (#297)", async (env) => {
+    const page = await openPopup(env.ctx, env.popupUrl);
+    try {
+        await page.setViewportSize(POPUP_VIEWPORT);
+        for (const id of PASSWORD_ERROR_CONTAINERS) {
+            const { empty, filled } = await page.evaluate(
+                measurePasswordError,
+                id,
+            );
+            assert(
+                empty.belowHeight > 0,
+                "nothing is shown below #" + id + ", so nothing was measured",
+            );
+            assert(
+                filled.height === empty.height,
+                "#" +
+                    id +
+                    " is " +
+                    empty.height +
+                    "px empty and " +
+                    filled.height +
+                    "px with an error",
+            );
+            assert(
+                filled.belowTop === empty.belowTop,
+                "the element below #" +
+                    id +
+                    " moved " +
+                    (filled.belowTop - empty.belowTop) +
+                    "px when the error appeared",
+            );
+        }
+    } finally {
+        await page.close();
+    }
+});
+
 // --------------------------------------------- confirmation screen (#238)
 //
 // The screen that decides what gets signed. The arithmetic underneath it

tests/flashLine.test.js

@@ -0,0 +1,130 @@
+// The flash line (#252). #flash-msg reserves one line and cuts a message too
+// long for it with an ellipsis; that is measured in a real browser by
+// tests/e2e/run.js. Here: showFlash() keeps the whole message readable in the
+// line's title, and the two add-token screens flash a fixed line, not the text
+// of whatever error adding the token threw.
+
+const ADDRESS = "0x1111111111111111111111111111111111111111";
+
+let elements;
+
+function fakeElement() {
+    return {
+        value: "",
+        textContent: "",
+        title: "",
+        style: {},
+        listeners: {},
+        addEventListener(event, handler) {
+            this.listeners[event] = handler;
+        },
+    };
+}
+
+// Stands in for document.getElementById(): one fake element per id.
+function element(id) {
+    return (elements[id] ||= fakeElement());
+}
+
+beforeEach(() => {
+    jest.resetModules();
+    elements = {};
+    globalThis.document = { getElementById: element };
+    // state.js reads chrome.storage.local at load.
+    globalThis.chrome = {
+        storage: { local: { get: async () => ({}), set: async () => {} } },
+    };
+});
+
+afterEach(() => {
+    jest.dontMock("../src/popup/views/helpers");
+    jest.dontMock("../src/shared/state");
+    jest.dontMock("../src/shared/balances");
+    jest.restoreAllMocks();
+    jest.useRealTimers();
+    delete globalThis.document;
+    delete globalThis.chrome;
+});
+
+test("showFlash() puts the whole message in the title, and clears both", () => {
+    jest.useFakeTimers();
+    const { showFlash } = require("../src/popup/views/helpers");
+
+    showFlash("Saved.");
+    expect(element("flash-msg").textContent).toBe("Saved.");
+    expect(element("flash-msg").title).toBe("Saved.");
+
+    jest.advanceTimersByTime(2000);
+    expect(element("flash-msg").textContent).toBe("");
+    expect(element("flash-msg").title).toBe("");
+});
+
+describe.each([
+    ["addToken", "add-token-address", "btn-add-token-confirm"],
+    [
+        "settingsAddToken",
+        "settings-addtoken-address",
+        "btn-settings-addtoken-manual",
+    ],
+])("adding a token on %s", (view, field, button) => {
+    let flashes;
+    let errors;
+
+    // Clicks the screen's add button with lookupTokenInfo() and saveState()
+    // replaced by the given functions.
+    async function add(lookupTokenInfo, saveState) {
+        flashes = [];
+        errors = jest.spyOn(console, "error").mockImplementation(() => {});
+        jest.spyOn(console, "log").mockImplementation(() => {});
+        jest.doMock("../src/shared/balances", () => ({ lookupTokenInfo }));
+        jest.doMock("../src/shared/state", () => ({
+            state: { trackedTokens: [] },
+            saveState,
+        }));
+        jest.doMock("../src/popup/views/helpers", () => ({
+            $: element,
+            showView: () => {},
+            showFlash: (msg) => flashes.push(msg),
+            escapeHtml: (s) => s,
+            goBack: () => {},
+        }));
+
+        require("../src/popup/views/" + view).init({
+            doRefreshAndRender: () => {},
+        });
+        element(field).value = ADDRESS;
+        await element(button).listeners.click();
+    }
+
+    test("a failed save flashes a fixed line and logs the error", async () => {
+        const detail = "A sentence about the stored record. ".repeat(4);
+
+        await add(
+            async () => ({ symbol: "TKN", decimals: 18, name: "Token" }),
+            async () => {
+                throw new Error(detail);
+            },
+        );
+
+        expect(flashes).toEqual(["Could not add the token."]);
+        expect(errors).toHaveBeenCalledWith(
+            "[AutistMask]",
+            "Adding token failed for",
+            ADDRESS,
+            detail,
+        );
+    });
+
+    test("a contract that is not a token flashes the lookup message", async () => {
+        const detail = "Not a valid ERC-20 token (symbol() failed).";
+
+        await add(
+            async () => {
+                throw new Error(detail);
+            },
+            async () => {},
+        );
+
+        expect(flashes).toEqual([detail]);
+    });
+});

tests/inpageErrors.test.js

@@ -49,11 +49,12 @@ class StubCustomEvent extends StubEvent {
     }
 }
 
-// Every code the background emits on the RPC path today, read out of
-// src/background/index.js. The provider must not know this list — it passes
-// through whatever arrived — but the cases below are the real ones.
+// Examples of codes the background emits on the RPC path, read out of
+// src/background/index.js. The provider must not know any list of codes — it
+// passes through whatever arrived — but the cases below are real ones.
 const REJECTED = 4001; // user rejected the request
 const UNAUTHORIZED = 4100; // site not connected / wrong address
+const UNSUPPORTED_METHOD = 4200; // a method the wallet does not implement
 const UNRECOGNIZED_CHAIN = 4902; // switch/add to an unsupported chain
 
 // A stub window with the four things inpage.js touches: message listeners,
@@ -115,6 +116,41 @@ async function rejectionFrom(start, response) {
     return outcome.error;
 }
 
+// The reply the real background worker (src/background/index.js) sends for
+// `method`, loaded against just enough of the extension API to receive one
+// RPC message. Same shape as tests/coldWorkerChainId.test.js.
+function backgroundReply(method) {
+    jest.resetModules();
+    jest.doMock("../src/shared/alarms", () => ({
+        BALANCE_REFRESH_ALARM: "balance",
+        BALANCE_REFRESH_PERIOD_MINUTES: 1,
+        ensureRecurringAlarms: async () => {},
+        registerAlarmHandlers: () => {},
+    }));
+
+    let messageListener = null;
+    global.chrome = {
+        runtime: {
+            onMessage: {
+                addListener: (fn) => {
+                    messageListener = fn;
+                },
+            },
+            onConnect: { addListener: () => {} },
+        },
+    };
+
+    require("../src/background/index");
+
+    return new Promise((resolve) => {
+        messageListener(
+            { type: "AUTISTMASK_RPC", method, params: [] },
+            { origin: "https://dapp.example" },
+            resolve,
+        );
+    });
+}
+
 describe("an EIP-1193 code reaches the page", () => {
     test("a user rejection arrives as code 4001", async () => {
         const err = await rejectionFrom(
@@ -164,8 +200,9 @@ describe("an EIP-1193 code reaches the page", () => {
         expect(err.message).toBe(message);
     });
 
-    // The provider is not allowed to know the list above: a code added to the
-    // background later must reach the page without this file being edited.
+    // The provider is not allowed to know the codes above: any other code,
+    // including one added to the background later, must reach the page
+    // without inpage.js being edited.
     test("a code the provider has never heard of is passed through", async () => {
         const err = await rejectionFrom(
             (p) => p.request({ method: "eth_accounts" }),
@@ -203,6 +240,26 @@ describe("an EIP-1193 code reaches the page", () => {
     });
 });
 
+// The reply here is the background's own, not one written in this file: it
+// used to carry no code for a method the wallet does not implement
+// (https://git.eeqj.de/sneak/AutistMask/issues/279), so a site probing for an
+// optional method could not tell "not implemented" from "the call failed".
+describe("a method the wallet does not implement", () => {
+    afterEach(() => {
+        delete global.chrome;
+    });
+
+    test("reaches the page as code 4200", async () => {
+        const method = "wallet_noSuchMethod";
+        const err = await rejectionFrom(
+            (p) => p.request({ method }),
+            await backgroundReply(method),
+        );
+        expect(err.code).toBe(UNSUPPORTED_METHOD);
+        expect(err.message).toBe("Unsupported method: " + method);
+    });
+});
+
 describe("the message is untouched", () => {
     test("a coded error keeps the message byte for byte", async () => {
         const message =

tests/uniswap.test.js

@@ -5,6 +5,8 @@ const ROUTER_ADDR = "0x66a9893cc07d91d95644aedd05d03f95e1dba8af";
 const USDT_ADDR = "0xdAC17F958D2ee523a2206206994597C13D831ec7";
 const WETH_ADDR = "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2";
 const USDC_ADDR = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
+const DAI_ADDR = "0x6B175474E89094C44Da98b954EedeAC495271d0F";
+const SEPOLIA_WETH_ADDR = "0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14";
 const USER_ADDR = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
 
 // AutistMask's first-ever swap, 2026-02-27.
@@ -75,6 +77,14 @@ function encodeV2SwapExactIn(recipient, amountIn, amountOutMin, pathAddrs) {
     );
 }
 
+// Helper: encode a V2_SWAP_EXACT_OUT input (command 0x09)
+function encodeV2SwapExactOut(recipient, amountOut, amountInMax, pathAddrs) {
+    return coder.encode(
+        ["address", "uint256", "uint256", "address[]", "bool"],
+        [recipient, amountOut, amountInMax, pathAddrs, true],
+    );
+}
+
 // Helper: encode a V3_SWAP_EXACT_IN input (command 0x00)
 function encodeV3SwapExactIn(recipient, amountIn, amountOutMin, pathTokens) {
     // V3 path: token(20) + fee(3) + token(20) ...
@@ -223,6 +233,233 @@ describe("uniswap decoder", () => {
         expect(minOut.value).toContain("WETH");
     });
 
+    // Buy exactly 0.5 WETH for at most 1,500 USDC, paid by the user, sent to
+    // the caller (the router's MSG_SENDER recipient, address(1)).
+    test("decodes V2_SWAP_EXACT_OUT, stating the input amount as a maximum", () => {
+        const data = buildExecute(
+            "0x09", // V2_SWAP_EXACT_OUT
+            [
+                encodeV2SwapExactOut(
+                    "0x0000000000000000000000000000000000000001",
+                    500000000000000000n, // amountOut: 0.5 WETH
+                    1500000000n, // amountInMax: 1,500 USDC (6 decimals)
+                    [USDC_ADDR, WETH_ADDR],
+                ),
+            ],
+            1767225600n,
+        );
+
+        const result = uniswap.decode(data, ROUTER_ADDR);
+        expect(result.name).toBe("Swap USDC → WETH");
+        expect(detail(result, "Token In").address).toBe(USDC_ADDR);
+        expect(detail(result, "Token Out").address).toBe(WETH_ADDR);
+
+        // The wait, success and error screens show rawValue as the amount, so
+        // it says "Up to" as well.
+        const amount = detail(result, "Amount");
+        expect(amount.value).toBe("Up to 1500.0000 USDC");
+        expect(amount.rawValue).toBe("Up to 1500.0000");
+
+        expect(detail(result, "Min. received").value).toBe("0.5000 WETH");
+    });
+
+    // Buy exactly 1,500 USDC for at most 0.5 ETH: WRAP_ETH of the maximum, the
+    // swap, then UNWRAP_WETH of 0, which returns the ETH the swap did not spend.
+    test("a V2 exact-out swap paid in ETH shows the token it buys and a maximum", () => {
+        const data = buildExecute(
+            solidityPacked(["uint8", "uint8", "uint8"], [0x0b, 0x09, 0x0c]),
+            [
+                encodeWrapEth(ROUTER_ADDR, 500000000000000000n),
+                encodeV2SwapExactOut(
+                    USER_ADDR,
+                    1500000000n, // amountOut: 1,500 USDC
+                    500000000000000000n, // amountInMax: 0.5 WETH
+                    [WETH_ADDR, USDC_ADDR],
+                ),
+                encodeWrapEth(USER_ADDR, 0n), // UNWRAP_WETH same encoding
+            ],
+            9999999999n,
+        );
+
+        const result = uniswap.decode(data, ROUTER_ADDR);
+        expect(result.name).toBe("Swap ETH → USDC");
+
+        const amount = detail(result, "Amount");
+        expect(amount.value).toBe("Up to 0.5000 ETH");
+        expect(amount.rawValue).toBe("Up to 0.5000");
+
+        expect(detail(result, "Token Out").address).toBe(USDC_ADDR);
+        expect(detail(result, "Min. received").value).toBe("1500.0000 USDC");
+    });
+
+    // Buy exactly 0.5 ETH for at most 1,500 USDC under a permit: the swap buys
+    // WETH and UNWRAP_WETH turns it into ETH.
+    test("a V2 exact-out swap that buys ETH shows ETH and the permit as a maximum", () => {
+        const data = buildExecute(
+            solidityPacked(["uint8", "uint8", "uint8"], [0x0a, 0x09, 0x0c]),
+            [
+                encodePermit2(USDC_ADDR, 1500000000n, ROUTER_ADDR),
+                encodeV2SwapExactOut(
+                    ROUTER_ADDR,
+                    500000000000000000n, // amountOut: 0.5 WETH
+                    1500000000n, // amountInMax: 1,500 USDC
+                    [USDC_ADDR, WETH_ADDR],
+                ),
+                encodeWrapEth(USER_ADDR, 500000000000000000n), // UNWRAP_WETH
+            ],
+            9999999999n,
+        );
+
+        const result = uniswap.decode(data, ROUTER_ADDR);
+        expect(result.name).toBe("Swap USDC → ETH");
+        expect(detail(result, "Amount").value).toBe("Up to 1500.0000 USDC");
+        expect(detail(result, "Token Out").value).toBe("ETH");
+        expect(detail(result, "Min. received").value).toBe("0.5000 ETH");
+    });
+
+    // Paid in a token, an UNWRAP_WETH of 0 after a swap that buys something
+    // other than WETH leaves the output side as it is: Token Out and Min.
+    // received are the token bought and its figure, not ETH.
+    test.each([
+        {
+            paidIn: "WETH",
+            tokenIn: WETH_ADDR,
+            amountInMax: 500000000000000000n, // 0.5 WETH
+            tokenOut: USDC_ADDR,
+            amountOut: 1300000000n, // 1,300 USDC
+            minReceived: "1300.0000 USDC",
+        },
+        {
+            paidIn: "USDC",
+            tokenIn: USDC_ADDR,
+            amountInMax: 8000000n, // 8 USDC
+            tokenOut: DAI_ADDR,
+            amountOut: 7000000000000000000n, // 7 DAI
+            minReceived: "7.0000 DAI",
+        },
+    ])(
+        "a V2 exact-out swap paid in $paidIn, then UNWRAP_WETH, shows the token it buys",
+        ({ tokenIn, amountInMax, tokenOut, amountOut, minReceived }) => {
+            const data = buildExecute(
+                solidityPacked(["uint8", "uint8", "uint8"], [0x0a, 0x09, 0x0c]),
+                [
+                    encodePermit2(tokenIn, amountInMax, ROUTER_ADDR),
+                    encodeV2SwapExactOut(USER_ADDR, amountOut, amountInMax, [
+                        tokenIn,
+                        tokenOut,
+                    ]),
+                    encodeWrapEth(USER_ADDR, 0n), // UNWRAP_WETH
+                ],
+                9999999999n,
+            );
+
+            const result = uniswap.decode(data, ROUTER_ADDR);
+            expect(detail(result, "Token Out").address).toBe(tokenOut);
+            expect(detail(result, "Min. received").value).toBe(minReceived);
+        },
+    );
+
+    // An exact-in swap is held to the same rule: buying USDC, then UNWRAP_WETH,
+    // receives USDC.
+    test("an exact-in swap to a token other than WETH, then UNWRAP_WETH, shows that token", () => {
+        const data = buildExecute(
+            solidityPacked(["uint8", "uint8"], [0x08, 0x0c]),
+            [
+                encodeV2SwapExactIn(USER_ADDR, 2000000n, 1900000n, [
+                    USDT_ADDR,
+                    USDC_ADDR,
+                ]),
+                encodeWrapEth(USER_ADDR, 0n), // UNWRAP_WETH
+            ],
+            9999999999n,
+        );
+
+        const result = uniswap.decode(data, ROUTER_ADDR);
+        expect(result.name).toBe("Swap USDT → USDC");
+        expect(detail(result, "Token Out").address).toBe(USDC_ADDR);
+        expect(detail(result, "Min. received").value).toBe("1.9000 USDC");
+    });
+
+    // Paid in ETH, with an exact-out step, the last swap step buys WETH, so
+    // UNWRAP_WETH makes the output ETH.
+    test("an ETH-paid swap whose last step buys WETH, then UNWRAP_WETH, shows ETH", () => {
+        const data = buildExecute(
+            solidityPacked(
+                ["uint8", "uint8", "uint8", "uint8"],
+                [0x0b, 0x09, 0x08, 0x0c],
+            ),
+            [
+                encodeWrapEth(ROUTER_ADDR, 500000000000000000n),
+                encodeV2SwapExactOut(
+                    ROUTER_ADDR,
+                    1500000000n, // amountOut: 1,500 USDC
+                    500000000000000000n, // amountInMax: 0.5 WETH
+                    [WETH_ADDR, USDC_ADDR],
+                ),
+                encodeV2SwapExactIn(
+                    ROUTER_ADDR,
+                    1500000000n, // amountIn: 1,500 USDC
+                    400000000000000000n, // amountOutMin: 0.4 WETH
+                    [USDC_ADDR, WETH_ADDR],
+                ),
+                encodeWrapEth(USER_ADDR, 0n), // UNWRAP_WETH
+            ],
+            9999999999n,
+        );
+
+        const result = uniswap.decode(data, ROUTER_ADDR);
+        expect(detail(result, "Token Out").value).toBe("ETH");
+        expect(detail(result, "Min. received").value).toBe("0.4000 ETH");
+    });
+
+    // Sepolia's WETH is a different contract; UNWRAP_WETH makes it ETH too.
+    test("a swap to Sepolia WETH, then UNWRAP_WETH, shows ETH", () => {
+        const data = buildExecute(
+            solidityPacked(["uint8", "uint8"], [0x08, 0x0c]),
+            [
+                encodeV2SwapExactIn(USER_ADDR, 1000000n, 500000000000000n, [
+                    USDC_ADDR,
+                    SEPOLIA_WETH_ADDR,
+                ]),
+                encodeWrapEth(USER_ADDR, 0n), // UNWRAP_WETH
+            ],
+            9999999999n,
+        );
+
+        const result = uniswap.decode(data, ROUTER_ADDR);
+        expect(detail(result, "Token Out").value).toBe("ETH");
+        expect(detail(result, "Min. received").value).toBe("0.0005 ETH");
+    });
+
+    // A step that states a Min. received figure but names no output token has
+    // set the output side, so UNWRAP_WETH does not make it ETH: nothing says
+    // the figure is counted in WETH.
+    test("a step with a minimum but no output token, then UNWRAP_WETH, names no token", () => {
+        const data = buildExecute(
+            solidityPacked(["uint8", "uint8"], [0x10, 0x0c]),
+            [
+                encodeV4Swap(new Uint8Array([V4_SWAP_EXACT_IN]), [
+                    encodeV4ExactIn(
+                        USDC_ADDR,
+                        [], // no path: this step names no output currency
+                        1000000000n, // 1,000 USDC
+                        400000000000000000n, // amountOutMin
+                    ),
+                ]),
+                encodeWrapEth(USER_ADDR, 0n), // UNWRAP_WETH
+            ],
+            9999999999n,
+        );
+
+        const result = uniswap.decode(data, ROUTER_ADDR);
+        expect(detail(result, "Token Out").value).toBe(
+            "Unknown (not named in the calldata)",
+        );
+        expect(detail(result, "Min. received").value).toBe(
+            "400000000000000000 base units (decimals unknown)",
+        );
+    });
+
     test("decodes V3_SWAP_EXACT_IN with known tokens", () => {
         const data = buildExecute(
             "0x00", // V3_SWAP_EXACT_IN

tests/unknownScaleSend.test.js

@@ -382,8 +382,56 @@ describe("a scale the explorer's own rows disagree about", () => {
         );
     });
 
+    // https://git.eeqj.de/sneak/AutistMask/issues/377. The Send screen read the
+    // stored balance and said "5.0000 NOVEL", the confirmation screen it leads
+    // to said "unknown (NOVEL)", and the fee message asked the user to go back
+    // and try again, which cannot supply a scale.
+    test("reads the same on the Send screen and the confirmation screen, and the fee message names the scale", async () => {
+        await fetchOntoBoth([novel("6", 5000000n)], [novel("18", FIVE_WETH)]);
+        state.selectedToken = NOVEL;
+        send.updateSendBalance();
+        expect(text("send-balance")).toBe("Current balance: unknown (NOVEL)");
+
+        const txInfo = await reviewSend(NOVEL, "1.5");
+        confirmTx.show(txInfo);
+        await settle();
+        expect(text("confirm-balance")).toBe("unknown (NOVEL)");
+        expect(text("confirm-fee-unknown-error")).toBe(
+            "The network fee could not be estimated, because this wallet" +
+                " does not know how many decimal places this token uses, so" +
+                " this transaction cannot be sent.",
+        );
+        expect(el("confirm-fee-unknown-error").style.visibility).toBe(
+            "visible",
+        );
+    });
+
+    test("while a fee that fails for any other reason keeps its retry", async () => {
+        await fetchOntoBoth([novel("6", 5000000n)], [novel("6", 5000000n)]);
+        const txInfo = await reviewSend(NOVEL, "1.5");
+        const getFeeData = mockProvider.getFeeData;
+        mockProvider.getFeeData = async () => {
+            throw new Error("the node did not answer");
+        };
+        try {
+            confirmTx.show(txInfo);
+            await settle();
+        } finally {
+            mockProvider.getFeeData = getFeeData;
+        }
+        expect(text("confirm-fee-amount")).toBe("Unable to estimate");
+        expect(text("confirm-fee-unknown-error")).toBe(
+            "The network fee could not be estimated, so this transaction" +
+                " cannot be checked against your balance. Please go back and" +
+                " try again.",
+        );
+    });
+
     test("while agreeing rows leave the scale usable", async () => {
         await fetchOntoBoth([novel("6", 5000000n)], [novel("6", 5000000n)]);
+        state.selectedToken = NOVEL;
+        send.updateSendBalance();
+        expect(text("send-balance")).toBe("Current balance: 5.0000 NOVEL");
         const txInfo = await reviewSend(NOVEL, "1.5");
         expect(txInfo.tokenDecimals).toBe(6);
         expect(txInfo.tokenBalance).toBe("5.0");