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+balance, formatted at one of those scales, is withdrawn with it.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
 
@@ -1395,7 +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**
@@ -1413,7 +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
@@ -1429,7 +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

TODO.md

@@ -45,6 +45,54 @@ 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

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/popup/index.html

@@ -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/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/send.js

@@ -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 + ")"
@@ -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/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);
             }

tests/e2e/run.js

@@ -1449,6 +1449,81 @@ test("an over-long flash message keeps to one line (#252)", async (env) => {
     }
 });
 
+// --------------------------------------- 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/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");