fix: a popup save no longer undoes a network switch the background saved during it (closes #641)

The popup's saveState() and the background's updateState() each read the
stored record, change it and write it back, and each was ordered only within
its own context, so a write by one could land between the other's read and
write and be lost. Both now hold the browser's lock (navigator.locks, shared
by every page and the background except a page in a Firefox private window)
from the read to the write, through withLock() in src/shared/browserApi.js;
the recovery screen's reset takes it too. The lock also orders a page's own
saves, so both per-context queues are gone. The unit tests get a small lock
from a Jest setup file.

Model: opus-5-5

README.md

@@ -418,6 +418,10 @@ Each group of these assertions records a coverage key and a final case demands
 the exact set, so a section that silently stopped running reddens the suite
 instead of quietly shrinking it.
 
+It also covers the red banner on the Settings screen: switching the network
+there to Sepolia must put up the `[TESTNET]` banner, and switching back to
+mainnet must take it down, both while Settings is still on screen.
+
 It also covers the confirmation screen, for both a native ETH send and an ERC-20
 send: Send disabled while the fee estimate is in flight, enabled once it lands,
 the fee block quoting the expected cost and the reserve separately, the distinct
@@ -430,6 +434,15 @@ reserve while sitting on the same side of the estimate, so swapping the two in
 what [#154](https://git.eeqj.de/sneak/AutistMask/issues/154) was, and it was
 previously correct by reading only.
 
+It also covers a send that Sign & Send refuses for its network fee: the stub
+node quotes an ordinary fee while the confirmation screen is drawn and one over
+the bound when Sign & Send asks again, and the refusal must broadcast nothing
+and leave the password field and Sign & Send where they were. It checks the same
+for a send refused because the selected wallet does not hold its From address:
+with the confirmation screen showing a send from the HD wallet, the key wallet
+is selected by writing it straight into extension storage, as another popup
+selecting it would save it, and the popup is reopened onto that screen.
+
 It also covers both ways the wait for a sent transaction's receipt ends on the
 error screen: lookups that still find no receipt 60 seconds after the broadcast,
 and six lookups in a row that fail. Each must show its own message, and Done
@@ -487,9 +500,12 @@ papered over:
   forced by clicking Reveal and the settings gear in one page task, which a
   person cannot do; the case a person can hit, the first decrypt after the popup
   opens while libsodium is still loading, is not driven.
-- Approval windows open at 1280x720 whatever size the extension asks for, so
-  whether an approval screen fits its window is checked in the Firefox suite
-  only.
+- Approval windows open at 1280x720 whatever size the extension asks for. The
+  site-connection prompt and the transaction approval are checked for sideways
+  scrolling at 396x600 by sizing the page itself for that measurement only, and
+  the rest of each test runs at 1280x720. That leaves out the window's frame and
+  the page widening its window, so whether an approval screen fits its window is
+  checked in the Firefox suite only.
 
 Any test that drives a failure path on purpose declares the `console.error` it
 is about to provoke, via `errors.expect()`. That is not a mute: the declaration
@@ -1014,15 +1030,15 @@ rendered differently on two screens.
 The native token's label is a network's `nativeCurrency` in
 `src/shared/networks.js`: `ETH` on mainnet, `SepoliaETH` on Sepolia. The
 wallet's balances and the Send screen, which sends on the active network, use
-the active network's. The confirmation screen uses the one of the network it is
-drawn for, the network active when it was shown, even after the network is
-switched in Settings while it is open. A transaction's figures use the one of
-the network its chain id names, whichever network is active: the value and fee
-on the approval screen, the amount on the wait, success and error screens, the
+the active network's. The confirmation screen uses the one of the network its
+transaction was reviewed on, the network active when Send showed it, even after
+the network is switched in Settings. A transaction's figures use the one of the
+network its chain id names, whichever network is active: the value and fee on
+the approval screen, the amount on the wait, success and error screens, the
 transaction history and the transaction detail screen, and the refusal of a fee
 above 1 ETH. A chain id that names no network reads `ETH`. Wherever this
 document shows ETH as the label of a native balance, value or fee, in a "Native
-ETH transfer" type line, in the contract-recipient warning or in that refusal,
+ETH transfer" type line, in the two recipient warnings or in that refusal,
 Sepolia shows `SepoliaETH`. The swap lines keep `ETH`, the router's own name for
 the native currency, and the ETH/USD price line, shown on mainnet only, keeps
 its fixed wording.
@@ -1077,42 +1093,49 @@ The rule and its exception live in `src/shared/amountDisplay.js` as
 confirmation screens display goes through the floored one — the ERC-20 amount,
 the ETH value and max fee (`src/popup/views/approval.js`), the swap's `Amount`
 and `Min. received` lines (`src/shared/uniswap.js`), the Send screen's
-`Current balance` (`src/popup/views/send.js`), and the balance and network fee
-on the confirmation screen for the wallet's own send
-(`src/popup/views/confirmTx.js`). Both screens render a network fee through
-`formatFee()` in `src/popup/views/helpers.js`, which prices the exact fee in USD
-rather than its truncated figure, so the same fee reads the same on both, USD
-value included. Balances are stored exactly (`src/shared/balances.js`), whatever
-decimals a token declares, so a balance below the floor reaches these screens as
-it is. The history list (`src/shared/transactions.js`) uses the unfloored one:
-the transaction detail view is the authoritative record and already shows exact
-precision. The balance lists use neither: they round to four places with
-`toFixed(4)` (`balanceLine()` in `src/popup/views/helpers.js`). The 4-decimal
-rule is unchanged everywhere else, including for amounts at or above the floor
-on the approval screens.
+`Current balance` (`src/popup/views/send.js`), and the amount, balance and
+network fee on the confirmation screen for the wallet's own send
+(`src/popup/views/confirmTx.js`), which hands the wait, success and error
+screens the amount as it showed it. The transaction is still signed for the
+exact amount, and its USD value is priced from it. Both screens render a network
+fee through `formatFee()` in `src/popup/views/helpers.js`, which prices the
+exact fee in USD rather than its truncated figure, so the same fee reads the
+same on both, USD value included. Balances are stored exactly
+(`src/shared/balances.js`), whatever decimals a token declares, so a balance
+below the floor reaches these screens as it is. The history list
+(`src/shared/transactions.js`) uses the unfloored one: the transaction detail
+view is the authoritative record and already shows exact precision. The balance
+lists use neither: they round to four places with `toFixed(4)` (`balanceLine()`
+in `src/popup/views/helpers.js`). The 4-decimal rule is unchanged everywhere
+else, including for amounts at or above the floor on the approval screens.
 
-The floor applies only where the token's scale is known. Where it is not, the
-approval screen states base units instead of a quantity — see Unknown token
-scale below — and no truncation happens at all.
+On the approval screen and the wait, success and error screens that carry its
+amount forward, the floor applies only where the token's scale is known. Where
+it is not, they state base units instead of a quantity — see Unknown token scale
+below — and no truncation happens at all. On ConfirmTx and the wait, success and
+error screens that follow it, the amount of a token whose scale is unknown,
+which cannot be sent, is the text from Send's amount field cut to four decimals
+with the same floor (`.5` reads `.5000`).
 
 **Specific Exception — unknown token scale:** Calldata carries base units and no
 scale, so every amount on the dApp approval screen needs the token's `decimals`.
-It is resolved from the bundled token list, then from the tokens the user
-tracks, then from what the block explorer reported for the contract
-(`resolveTokenDecimals()` in `src/shared/approvalAmount.js`). Where none of them
-answers, the amount is not formatted: the line reads
-`5000000000 base units (decimals unknown)`. A guessed scale is not an
-approximation but a different number — 1,000 units of a 6-decimal token
-formatted at 18 decimals reads `0.000000001` — on the screen whose only job is
-to state what is being authorized. Both amount paths of that screen take this
-rule: the ERC-20 `transfer`/`approve` line (`src/popup/views/approval.js`) and
-the swap's `Amount` and `Min. received` lines (`src/shared/uniswap.js`). The
-token permission warning on the signature screen takes the same rule for its
-amounts. An unbounded allowance or permit needs no scale to describe and is
-still shown as `Unlimited`. A source's answer counts only if it is a whole
-number from 0 to 80: `decimals()` returns a `uint8`, but `formatUnits()` cannot
-format more than 80 decimal places, so a token that reports 81 to 255 is shown
-as one whose scale nothing knows.
+It is resolved from the bundled token list, then from the tokens the user tracks
+on the network the transaction is for, then, when that is the active network,
+from what the block explorer reported for the contract in the wallet's balances,
+which are the active network's only (`resolveTokenDecimals()` in
+`src/shared/approvalAmount.js`). Where none of them answers, the amount is not
+formatted: the line reads `5000000000 base units (decimals unknown)`. A guessed
+scale is not an approximation but a different number — 1,000 units of a
+6-decimal token formatted at 18 decimals reads `0.000000001` — on the screen
+whose only job is to state what is being authorized. Both amount paths of that
+screen take this rule: the ERC-20 `transfer`/`approve` line
+(`src/popup/views/approval.js`) and the swap's `Amount` and `Min. received`
+lines (`src/shared/uniswap.js`). The token permission warning on the signature
+screen takes the same rule for its amounts. An unbounded allowance or permit
+needs no scale to describe and is still shown as `Unlimited`. A source's answer
+counts only if it is a whole number from 0 to 80: `decimals()` returns a
+`uint8`, but `formatUnits()` cannot format more than 80 decimal places, so a
+token that reports 81 to 255 is shown as one whose scale nothing knows.
 
 The rule holds only if nothing invents a scale UPSTREAM of it. Those three
 sources are read as authoritative, so a value written into one of them cannot be
@@ -1144,8 +1167,9 @@ 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
-read:
+decoded swap (see TxApproval below; `Min. received` reads `Min. paid out` unless
+only the user is paid, see Transaction Decoding), do not always read as a
+number. They can read:
 
 - A formatted quantity, e.g. `17.1900 USDT`, when the token's scale is known:
   truncated to four decimals, with the floor and the zero cases described above.
@@ -1155,26 +1179,22 @@ 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,
-  V2 exact-out or `WRAP_ETH` amount that large, which is not an allowance. The
+  amount at that maximum, which is an unbounded permit, or a V2 or V3 exact-in
+  or 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
+- `Up to <amount>`: the swap's `Amount` line, when the transaction has a V2 or
+  V3 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`, `All available (V4 open delta)` and
   `Whatever an earlier step sent to the pair (V2 already paid)` keep their
-  wording. When a V2 exact-out step sets `Min. received`, that line shows its
-  `amountOut`, the exact amount it buys.
+  wording. When a V2 or V3 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,
-  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.
+  whole open delta", so the calldata states no quantity. Transaction Decoding
+  below gives the steps whose amounts the line shows.
 - `Whatever an earlier step sent to the pair (V2 already paid)`: the swap's
   `Amount` line, when the amount it shows is a V2 exact-in `amountIn` of zero.
   The router reads that zero as "the pair already holds the input tokens": the
@@ -1190,22 +1210,67 @@ read:
   guarantees nothing: it sets `Token Out` and `Min. received` only when the
   output side holds no minimum, not even a zero one, at the point the check is
   reached, and otherwise leaves the current token and figure in place. A nonzero
-  `minBalance` sets both lines, as a swap step does.
+  `minBalance` sets both lines, as a swap step does. Only a check of the
+  transaction's sender's own balance sets either line; a check of any other
+  address sets neither (see Transaction Decoding). A `BALANCE_CHECK_ERC20` step
+  that the router lets fail without reverting the transaction (see Transaction
+  Decoding) guarantees nothing either, whatever its `minBalance`, and is read as
+  one whose `minBalance` is zero. A minimum stated by a V4 swap step the router
+  lets fail is likewise read as zero.
 
 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, or `Unknown (could not be decoded)` instead when a V4 swap action in
-the transaction could not be read (see Transaction Decoding below). A V4 step
-whose swap action could not be read still sets each side as a swap step does,
-and a side its `SETTLE` or `TAKE` did not name is then unknown: no other step's
-token or figure is shown for it. 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.
+the transaction could not be read or the transaction has an `EXECUTE_SUB_PLAN`
+step, which leaves both sides unknown (see Transaction Decoding below). A V4
+step with a swap action always sets the output side, and sets the input side
+only when no earlier step set it. It finds each side by three rules:
+
+1. Its input side is the currency its `SETTLE` or `SETTLE_ALL` names, or else
+   the one currency that some swap action in the step spends and none buys. Its
+   output side is the currency its `TAKE` or `TAKE_ALL` names, or else the one
+   currency that some swap action buys and none spends. If there is not exactly
+   one such currency, that side is unknown, and the step sets it as unknown with
+   no figure. A step that buys WETH with USDT and USDC with that WETH, with
+   nothing naming its sides, reads `Swap USDT → USDC`.
+2. Its `Amount` is the `amountIn` of the swap action that spends the input
+   currency. If several exact-in actions spend it, each with a stated amount, it
+   is their sum; in any other case the step gives no `Amount`. The decoder reads
+   no amount from an exact-out action, and an open delta is not a stated amount.
+   Its `Min. received` is found the same way, from the `amountOutMin` of the
+   actions that buy the output currency.
+3. If any swap action in the step could not be read, only `SETTLE`,
+   `SETTLE_ALL`, `TAKE` and `TAKE_ALL` name its sides, and the step gives no
+   `Amount` or `Min. received`. A side they did not name is unknown, and the
+   step sets it as unknown with no figure.
+
+Under each of these rules, when the user pays the step any of the input
+currency, its `Amount` is instead what the user pays it of that currency when
+the decoder knows that amount, and otherwise there is none (see Transaction
+Decoding). So a step whose USDT-for-USDC swap action could not be read, with a
+`SETTLE` of 400 USDT paid by the user, reads `Amount 400.0000 USDT`.
+
+A V4 step with no swap action sets only the sides its `SETTLE`, `SETTLE_ALL`,
+`TAKE` or `TAKE_ALL` names.
+
+An `UNWRAP_WETH` step makes `Token Out` ETH only when no step set the output
+side, or when the output side is WETH, on mainnet or Sepolia, that the step that
+set it paid to the router and that the router still holds when the `UNWRAP_WETH`
+runs (Transaction Decoding below gives what the router holds). The router
+unwraps only the WETH it holds, so WETH that step paid to the user, or to anyone
+else, stays WETH: a swap that pays the router WETH, then a swap that pays the
+user WETH, then an unwrap, shows WETH with the second swap's minimum. The
+minimum reads in ETH when that step paid all its WETH to the router. When it
+paid only part of it to the router, as a V4 step does that `TAKE`s some of its
+WETH to the user and the rest to the router, or paid the router WETH beside a
+payout the decoder cannot read, the swap shows ETH with no minimum: the decoder
+does not count how much of that step's minimum reaches the router, nor read the
+`UNWRAP_WETH`'s own minimum. A later step that sets the output side sets it
+anew. 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.
 
 The swap's `Deadline` line is the router's deadline as a UTC date and time, e.g.
 `2026-02-27 08:25:51`. A JavaScript date reaches only to 275760-09-13 00:00:00
@@ -1324,6 +1389,19 @@ carries a `schemaVersion` — `STATE_SCHEMA_VERSION` in
 `saveState()` and the background's `updateState()` both do, so whichever context
 wrote last, the record says which build's shape it is in.
 
+Each write reads the record, changes it and writes it back, holding a lock from
+the read to the write: the browser's own (`navigator.locks`), taken through
+`withLock()` in `src/shared/browserApi.js`. Every page of the extension and its
+background share it, except a page in a Firefox private window, which Firefox
+gives locks of its own (see https://git.eeqj.de/sneak/AutistMask/issues/646).
+The popup's `saveState()`, the background's `updateState()` and the
+StateRecovery reset all take it, so among the pages and the background that
+share it, no write lands between another write's read and its write, where it
+would be lost. Chrome has it from version 69, older than any Chrome that runs a
+Manifest V3 extension, in pages and in the service worker; Firefox from version
+96, older than the 115 `manifest/firefox.json` declares. Where it is missing, a
+write fails rather than going ahead without it.
+
 Version 1 is the shape that shipped before versions existed, so a stored record
 with no `schemaVersion` is version 1 rather than a defect: it loads normally and
 is migrated in place by being stamped on the first write. An upgrade never shows
@@ -1472,6 +1550,21 @@ such as an edit typed into Settings and not yet saved. Home is the one screen
 "Back" always re-renders, so the wallet list reflects anything that changed
 while the user was away from it.
 
+A network switch in Settings leaves every screen beneath Settings showing the
+previous network, so after it "Back" behaves as in a reopened popup: every
+screen on the stack counts as not yet rendered, and the stack is cut at the
+first screen that cannot be rendered from saved state, such as Send or AddToken,
+or at AddressToken for any token but the native one, because that token was
+picked on the previous network. The cut stack is saved with the switch, so a
+popup closed straight after it and reopened onto Settings lands in the same
+place. "Back" then renders the screen it lands on for the new network, and
+anything typed there and not saved, which belonged to the previous network, is
+dropped. ConfirmTx, WaitTx, SuccessTx, ErrorTx and TransactionDetail are
+rendered instead for the network of the transaction they show: the network it
+was reviewed on for ConfirmTx, and the network it was sent on for the others.
+Without a wallet the stack is not cut, because it starts at Welcome, which shows
+nothing from a network.
+
 Every screen that holds secret material in the page registers a cleanup with
 `onViewLeave()` (`src/popup/views/helpers.js`), which `showView()` runs on every
 exit from that screen rather than only on its "Back" button, so nothing secret
@@ -1713,45 +1806,55 @@ view would leave a wallet one click from deletion.
     - Token contract: full address + etherscan link (ERC-20 only)
     - 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). An ETH amount Send's "Max"
-      filled in is worked out again from this screen's own fee estimate when it
-      arrives, as the balance minus the reserve, and the transaction is signed
-      with that estimate's fee fields, so a fee fetched again at signing cannot
-      exceed what the amount leaves behind. The address keeps whatever part of
-      the reserve the transaction does not use. If the balance no longer covers
-      the fee, the amount is left as it was and the amount-plus-fee error below
-      blocks the send
-    - Your balance: the From address's balance on the network the screen is
-      drawn for, read from that network's RPC endpoint each time the screen is
-      shown, so a screen the popup reopens onto after the network was switched
-      states and checks the balance on the new network. "Loading..." until the
-      read returns, then value + symbol (USD in parentheses), or
+    - Amount: value + symbol (USD in parentheses), the value to four decimal
+      places with the nonzero floor, as on TxApproval (see Display Consistency),
+      however Send's amount field wrote it (`.5` and `0.5` both read `0.5000`).
+      For a token whose scale is unknown, which cannot be sent, the value is the
+      text from Send's amount field cut the same way (`.5` reads `.5000`). An
+      ETH amount Send's "Max" filled in is worked out again from this screen's
+      own fee estimate when it arrives, as the balance minus the reserve, and
+      the transaction is signed with that estimate's fee fields, so a fee
+      fetched again at signing cannot exceed what the amount leaves behind. The
+      address keeps whatever part of the reserve the transaction does not use.
+      If the balance could not be read or no longer covers the fee, the amount
+      is left as it was and one of the errors below blocks the send
+    - Your balance: the From address's balance on the network its transaction
+      was reviewed on, read from that network's RPC endpoint each time the
+      screen is shown, so a screen the popup reopens onto states and checks that
+      network's balance as it is then, whichever network is active. "Loading..."
+      until the read returns, then value + symbol (USD in parentheses), or
       `unknown (SYMBOL)` for a token whose scale is unknown or when the read
       failed. The amount check uses the same balances: the ETH balance, and for
       a token transfer the token balance as well
     - Network fee: "Estimating..." then two lines, or "Unable to estimate",
-      fetched async once the balance is read, from the same RPC endpoint as the
-      balance, even if the network is switched in Settings while the balance is
-      being read. The first line is what the transfer is expected to cost,
-      `gasLimit * gasPrice` (USD in parentheses); the second is the
-      `gasLimit * maxFeePerGas` reserve the node requires, which is what the
-      balance check gates on. The second line is omitted on a network with no
-      type-2 pricing, where the two are the same number, but its space is
-      reserved either way
+      fetched async once the balance is read. The first line is what the
+      transfer is expected to cost, `gasLimit * gasPrice` (USD in parentheses);
+      the second is the `gasLimit * maxFeePerGas` reserve the node requires,
+      which is what the balance check gates on. The second line is omitted on a
+      network with no type-2 pricing, where the two are the same number, but its
+      space is reserved either way
     - Warnings: inline warnings from the local checks (scam address, self-send)
       plus four reserved warning boxes made visible by the async checks —
-      recipient with no transaction history, recipient is a contract, burn
-      address, and an Etherscan phishing/scam label
-    - Errors (insufficient balance, or a balance that could not be read, which
-      asks the user to go back and try again), plus three reserved error boxes —
-      the 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 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
+      recipient that has never sent a transaction and holds no ETH, recipient is
+      a contract, burn address, and an Etherscan phishing/scam label. An address
+      that has received ETH but never sent a transaction still holds that ETH,
+      so it gets no warning
+    - Errors (an invalid amount), plus five reserved error boxes, so the balance
+      and the fee arriving later move nothing — the amount exceeds the balance
+      (for a token whose scale is unknown it says the token's balance is
+      unknown), the balance could not be read (it asks the user to go back and
+      try again), the 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 third and fourth are mutually exclusive
+      per transfer type, so only 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
+    - Three more reserved error boxes, made visible when "Sign & Send" refuses a
+      send because the active network changed, because the selected wallet does
+      not hold the From address, or because of its gas limit or fee (see
+      Transitions), so the refusal moves nothing
     - Password: an inline field on this screen, not a modal, with its own error
       line
     - "Sign & Send" button (disabled if errors, while the balance is being read,
@@ -1766,19 +1869,38 @@ view would leave a wallet one click from deletion.
       the contract's own answer is read at signing time only to be compared with
       it, and a disagreement is a refusal rather than a preference for either
       value (`src/shared/transferAmount.js`)
-    - "Sign & Send" after the active network was switched in Settings while this
-      screen was open → nothing is signed; "The active network changed after
-      this transaction was reviewed, so it was not sent. Please go back and
-      review it again." in the errors box, no screen change. The transaction
-      carries the chain id of the network the screen was shown for, so it cannot
-      be signed for another
+    - "Sign & Send" after the active network was switched in Settings since this
+      transaction was reviewed → nothing is signed; "The active network changed
+      after this transaction was reviewed, so it was not sent. Please go back
+      and review it again." in its own box, no screen change. After a switch,
+      "Back" from Settings draws this screen again from the saved transaction,
+      as a popup reopened onto it does; when Send is beneath it on the stack, as
+      when Send showed it in the same popup, "Back" lands below Send instead
+      (see the top of Screen Map). The transaction carries the chain id of the
+      network active when Send showed this screen, and keeps it when the screen
+      is drawn again from the saved transaction, so it cannot be signed for
+      another. The screen describes it on that network, whichever network is
+      active: its amounts are in that network's native currency, its USD values
+      are that network's, so a testnet transaction shows none, its From, To and
+      token contract links open that network's explorer, the balance read, the
+      fee estimate and the contract and never-sent recipient checks ask that
+      network's RPC endpoint, and the Etherscan label check asks that network's
+      explorer
+    - "Sign & Send" (correct password) when the gas limit, a fee per gas or the
+      total fee the RPC endpoint fills in at signing is over its bound in
+      `assertWithinCeilings()` (`src/shared/approvalVerify.js`) → nothing is
+      signed; "The gas limit or fee the RPC endpoint quoted for this transaction
+      is more than this wallet will sign for, so it was not sent. Please go back
+      and try again." in its own box, the same sentence for all three, no screen
+      change
     - "Sign & Send" (wrong password) → "Wrong password." on the password error
       line, no screen change
     - "Sign & Send" signs as the From address above, not as whichever address is
       selected: the two are saved separately, so the popup can reopen onto this
       screen with another address selected. When the selected wallet does not
-      hold the From address → full-sentence error on the password error line,
-      nothing sent (no screen change)
+      hold the From address → nothing is signed; "The selected wallet does not
+      hold the From address above, so nothing was sent. Please go back and send
+      again." in its own box, no screen change
     - "Sign & Send" (correct password, but the From address's key is refused,
       see Data Model) → nothing is signed → **ErrorTx** saying why
     - "Back" → **Send**
@@ -1798,14 +1920,17 @@ view would leave a wallet one click from deletion.
       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
-  persisted: closing and reopening the popup resumes the poll, with the elapsed
-  counter and the timeout deadline still measured from the original broadcast. A
-  lookup that fails is retried on the next tick rather than counted as a missing
-  receipt, because a failed lookup says nothing about the transaction; but six
-  failures in a row (60 seconds at the poll cadence) end the wait, so an RPC
-  that never answers cannot leave it running indefinitely. Any lookup that
-  answers resets that count.
+- **Behavior**: Polls `getTransactionReceipt` every 10 seconds. The screen
+  describes the transaction on the network it was sent on, whichever network is
+  active: the receipt is asked of that network's RPC endpoint, the one Settings
+  has for it, and the To and hash links open that network's explorer. The wait
+  is persisted: closing and reopening the popup resumes the poll, with the
+  elapsed counter and the timeout deadline still measured from the original
+  broadcast. A lookup that fails is retried on the next tick rather than counted
+  as a missing receipt, because a failed lookup says nothing about the
+  transaction; but six failures in a row (60 seconds at the poll cadence) end
+  the wait, so an RPC that never answers cannot leave it running indefinitely.
+  Any lookup that answers resets that count.
 - **Transitions**:
     - Receipt found → **SuccessTx**
     - A lookup that answers "no receipt" 60 seconds or more after broadcast →
@@ -1826,9 +1951,12 @@ view would leave a wallet one click from deletion.
     - Amount + symbol
     - To: color dot + full address + etherscan link, or for a contract creation
       the same sentence as on WaitTx
-    - Block number
+    - Block number + etherscan link
     - Transaction hash: full hash (tap to copy) + etherscan link
     - "Done" button
+- **Behavior**: As on WaitTx, every etherscan link on the screen opens the
+  explorer of the network the transaction was sent on, whichever network is
+  active.
 - **Transitions**:
     - "Done" in the approval popup → closes the popup window
     - "Done" otherwise → resets the navigation stack, then → **AddressToken**
@@ -1848,6 +1976,9 @@ view would leave a wallet one click from deletion.
     - Transaction hash section (hidden if broadcast failed before getting hash):
       full hash (tap to copy) + etherscan link
     - "Done" button
+- **Behavior**: As on WaitTx, every etherscan link on the screen opens the
+  explorer of the network the transaction was sent on, whichever network is
+  active.
 - **Transitions**:
     - "Done" in the approval popup → closes the popup window
     - "Done" otherwise → resets the navigation stack, then → **AddressToken**
@@ -1870,7 +2001,10 @@ view would leave a wallet one click from deletion.
 #### TransactionDetail (`transaction`)
 
 - **When**: User tapped a transaction row on Home, AddressDetail, or
-  AddressToken.
+  AddressToken. The screen describes the transaction on the network it was sent
+  on, whichever network is active: its block, network details, decoded details
+  and raw data are read from that network's Blockscout, the one Settings has for
+  it, and its etherscan links open that network's explorer.
 - **Elements** (grouped into logical blocks using light well containers; field
   labels are self-explanatory so groups have no headings):
     - "Transaction" heading, "Back" button
@@ -1878,7 +2012,11 @@ view would leave a wallet one click from deletion.
     - Type: transaction classification — one of: Native ETH Transfer, ERC-20
       Token Transfer, Swap, Token Approval, Contract Call, Contract Creation. A
       transfer with a token contract is an ERC-20 Token Transfer whatever symbol
-      the token reports.
+      the token reports. A call named `execute` or `multicall` is a Swap, here
+      and on its history row, only when it was sent to one of the Universal
+      Router addresses Uniswap publishes for the network it was sent on (see
+      Transaction Decoding); sent to any other contract, its history row shows
+      the method name and this line reads Contract Call.
     - Status: "Success" or "Failed"
     - From: blockie + color dot + full address (tap to copy) + etherscan link;
       ENS name if available
@@ -1909,13 +2047,18 @@ view would leave a wallet one click from deletion.
     - Contract address input
     - Status line ("Looking up token...", cleared or replaced on failure)
     - Common token quick-pick buttons (top 25 by market cap), which fill the
-      contract address input
+      contract address input. Shown on Ethereum Mainnet only, because the
+      bundled token list holds mainnet contracts
     - "Add" button
 - **Transitions**:
     - "Add" (valid contract) → tracks the token, pops the stack, and re-renders
       **AddressDetail**
     - "Add" with a token already tracked, a scam-listed address, or a failed
       contract lookup → flash message, no screen change
+    - "Add", then a network switch in Settings before the contract lookup
+      answers → nothing is tracked; "The active network changed before the
+      lookup finished, so the token was not added." flash message, no screen
+      change
     - "Back" → previous screen (AddressDetail)
 
 #### Settings (`settings`)
@@ -1926,16 +2069,19 @@ view would leave a wallet one click from deletion.
     - Wallets: one row per wallet with its name (tap to rename inline), a
       `[recovery phrase]` button on HD wallets only, and an `[x]` delete button,
       plus a "+ Add wallet" button
-    - Tracked Tokens: one row per tracked token with an `[x]` remove button,
-      plus a "+ Add token" button
+    - Tracked Tokens: one row per token tracked on the active network with an
+      `[x]` remove button, plus a "+ Add token" button
     - Display: "Show tracked tokens with zero balance" checkbox, "UTC
       Timestamps" checkbox, and a Theme selector (System / Light / Dark)
     - Network: network selector (Ethereum Mainnet / Sepolia Testnet). The
       network changes only here, or when the user approves a site's request on
       **NetworkApproval**; either way, switching restores the RPC and Blockscout
       endpoints last used on that network, or that network's defaults if it has
-      none, and sends `chainChanged` with the new chain id to every open tab.
-      Choosing the network already active changes nothing and sends nothing
+      none, and the tokens tracked on that network, and sends `chainChanged`
+      with the new chain id to every open tab. A token is tracked only on the
+      network it was added on, because a contract address names a token on one
+      network only. Choosing the network already active changes nothing and
+      sends nothing
     - Ethereum RPC: endpoint URL input + "Save" button (validated against
       `eth_chainId` before being saved)
     - Blockscout API: endpoint URL input + "Save" button (validated against
@@ -1980,7 +2126,8 @@ view would leave a wallet one click from deletion.
     - `[x]` on a denied site → forgets the refusal, in place; it connects
       nothing and tells the background nothing
     - Ten clicks on the version → reveals the Debug well (no screen change)
-    - "Back" (or Settings gear again) → previous screen (Home)
+    - "Back" (or Settings gear again) → previous screen (Home); after a network
+      switch, the stack is cut first (see the top of Screen Map)
 
 #### ShowRecoveryPhrase (`show-phrase`)
 
@@ -2021,7 +2168,9 @@ view would leave a wallet one click from deletion.
 - **Elements**:
     - "Back" button, "Delete Wallet" heading
     - Warning naming the wallet and stating that deletion is permanent and any
-      funds are unrecoverable without the recovery phrase
+      funds are unrecoverable without the recovery phrase, the private key or
+      the extended private key, according to the wallet's kind
+      (`keyMaterialName()` in `src/popup/views/helpers.js`)
     - Password input
     - Error line
     - "Confirm Delete" button
@@ -2062,9 +2211,10 @@ view would leave a wallet one click from deletion.
       cannot be unlocked again, and that no password is needed to delete it
     - What deletion does and does not do: it erases the copy of the key stored
       on this device; nothing on chain changes and no money is moved
-    - The route back — adding the wallet again with the recovery phrase and a
-      new password — and, in bold, that without that phrase written down the
-      deletion loses everything the wallet holds, forever
+    - The route back — adding the wallet again, with a new password, from a kept
+      copy of its recovery phrase, private key or extended private key (named as
+      on DeleteWallet) — and, in bold, that without that copy the deletion loses
+      everything the wallet holds, forever
     - That the other wallets are not touched
     - The wallet's name, and a text input asking for it to be typed back. A name
       that shows nothing at all (only spaces, or only characters that paint
@@ -2122,8 +2272,9 @@ view would leave a wallet one click from deletion.
       the address **only if it has on-chain activity**. An address that was
       never used is not found by that scan. The text is written by
       `recoveryPathText()` rather than sitting in `index.html`, so it can name
-      the wallet's own kind of key material: an xprv wallet has no recovery
-      phrase to re-import.
+      the wallet's own kind of key material through `keyMaterialName()`, as
+      DeleteWallet and DeleteWalletLostPassword do: an xprv wallet has no
+      recovery phrase to re-import.
     - A warning when the address holds anything, ETH or any tracked ERC-20,
       followed by the holdings themselves via `balanceLinesForAddress()` and the
       USD total via `formatAddressTotal()` (see
@@ -2159,7 +2310,8 @@ view would leave a wallet one click from deletion.
 #### SettingsAddToken (`settings-addtoken`)
 
 - **When**: User tapped "+ Add token" in Settings. Tokens added here are tracked
-  across every address, unlike AddToken which is reached from one address.
+  across every address on the active network, unlike AddToken which is reached
+  from one address.
 - **Elements**:
     - "Back" button, "Add Token" heading
     - Instruction text
@@ -2168,11 +2320,19 @@ view would leave a wallet one click from deletion.
     - "Or pick from top 100:" dropdown (already-tracked tokens are disabled) +
       "Add selected" button
     - "Or enter contract address:" input, a status line, and an "Add" button
+    - The two lists from the bundled token list, "Top tokens:" and "Or pick from
+      top 100:", are shown on Ethereum Mainnet only, because that list holds
+      mainnet contracts. On any other network the contract address is the only
+      add path
 - **Transitions**:
-    - Any of the three add paths, on success → adds the token and shows an
+    - Any of the add paths shown, on success → adds the token and shows an
       "Added SYMBOL" flash message (no screen change)
     - A duplicate, a scam-listed address, or a failed contract lookup → flash
       message, no screen change
+    - "Add" by contract address, then a network switch in Settings before the
+      lookup answers → nothing is tracked; "The active network changed before
+      the lookup finished, so the token was not added." flash message, no screen
+      change
     - "Back" → previous screen (Settings)
 
 #### SiteApproval (`approve-site`)
@@ -2186,14 +2346,17 @@ view would leave a wallet one click from deletion.
   code `4100` and opens no prompt. Two such origins are `null`, which the
   browser reports for a page with an opaque origin, such as one its server
   sandboxes with a Content-Security-Policy, and `file://`, which Chrome reports
-  for a local file. The background script prefers the toolbar popup
-  (`action.openPopup()`) and falls back to a separate popup window
-  (`src/background/index.js`, `requestApproval()`). Only one exists per site at
-  a time: a further connection request from a site whose prompt is still
-  unanswered is refused with EIP-1193 code `-32002` and opens no new prompt. If
-  that prompt was in a toolbar popup that closed before it connected, and the
-  toolbar popup has since been set to open something else, the refused request
-  shows that prompt again.
+  for a local file. Nor is such a page told the active address by
+  `accountsChanged`, even at a connected site's URL: the background names the
+  origin of the tab's URL on the event, and the content script passes the
+  address on only to a page whose own origin is that one. The background script
+  prefers the toolbar popup (`action.openPopup()`) and falls back to a separate
+  popup window (`src/background/index.js`, `requestApproval()`). Only one exists
+  per site at a time: a further connection request from a site whose prompt is
+  still unanswered is refused with EIP-1193 code `-32002` and opens no new
+  prompt. If that prompt was in a toolbar popup that closed before it connected,
+  and the toolbar popup has since been set to open something else, the refused
+  request shows that prompt again.
 - **Elements**:
     - "Connection Request" heading
     - Phishing warning banner (shown when the hostname is on the phishing
@@ -2246,17 +2409,28 @@ view would leave a wallet one click from deletion.
     - Site origin (bold, scheme and port included) + "wants to send a
       transaction"
     - Decoded action (if calldata is recognized): action name, token details,
-      amounts, steps, deadline (see Transaction Decoding)
+      amounts, what each swap step spends that the `Amount` line does not give,
+      what each `PERMIT2_TRANSFER_FROM` moves and where to, steps, deadline, and
+      unless a swap pays only the From address, a `Paid to` line for each other
+      address it pays, or saying that a token stays in the router or who it pays
+      is unknown (see Transaction Decoding)
     - From: color dot + full address + etherscan link
     - 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
+    - Value: amount in ETH (4 decimal places with the nonzero floor, USD in
+      parentheses)
+    - Network fee (max): gas limit × fee per gas in ETH (4 decimal places with
+      the nonzero floor, USD in parentheses), with the gas limit and the fee per
+      gas in gwei below it
     - Network and nonce
     - Raw data: full calldata displayed inline (shown if present)
     - Password input and an error line
     - "Confirm" / "Reject" buttons
+- **Behavior**: Every etherscan link on the screen opens the explorer of the
+  network the transaction was populated on, whichever network is active. The
+  Value and Network fee lines each give the USD value of the exact amount at the
+  price on that network, as on ConfirmTx: none for a testnet transaction or one
+  on a chain id that names no network.
 - **Transitions**:
     - "Confirm" (correct password) → decrypts and signs the transaction it was
       shown, exactly as shown, hands the signed transaction to the background to
@@ -2384,8 +2558,9 @@ view would leave a wallet one click from deletion.
 - **Transitions**:
     - "Switch" → closes popup; the background switches the network as
       **Settings** does, restoring the RPC and Blockscout endpoints last used on
-      that network (or that network's defaults if it has none), sends
-      `chainChanged` to every open tab, and answers the site with success
+      that network (or that network's defaults if it has none) and the tokens
+      tracked on that network, sends `chainChanged` to every open tab, and
+      answers the site with success
     - "Reject" → closes popup; the site is answered with EIP-1193 code 4001 and
       nothing changes
     - Popup window closed without answering → the same as "Reject"
@@ -2862,11 +3037,236 @@ Currently supported:
   or recipient, and amount.
 - **Uniswap Universal Router**: `execute()` calls — shows swap direction (e.g.
   "Swap USDT → ETH"), token addresses, amounts, execution steps, and deadline.
-  Decodes Permit2, V2/V3/V4 swaps, wrap/unwrap, and balance checks. A V4 swap
-  action is read only in the parameter shape deployed on mainnet and Sepolia,
-  not in the newer one on `v4-periphery` `main`, which adds a `minHopPriceX36`
-  field. An action in any other shape is not read, and its step is listed as
-  `V4 Swap (could not be decoded)`.
+  The swap summary is shown only for a transaction sent to one of the Universal
+  Router addresses Uniswap publishes for the network: on TxApproval the network
+  the transaction is for, on TransactionDetail the network it was sent on. The
+  same calldata sent to any other address is shown as raw data. Decodes Permit2,
+  V2/V3/V4 swaps, wrap/unwrap, and balance checks. A V3 swap step's path is read
+  as the router reads it: a `V3_SWAP_EXACT_IN` path runs from the token it
+  spends to the token it buys, and a `V3_SWAP_EXACT_OUT` path from the token it
+  buys to the token it spends, so that step's input token is its path's last
+  token and its output token the first. The router reads a path as one token
+  address followed by whole hops of a 3-byte fee and a token address, and
+  ignores any bytes after the last hop, so the decoder does not read a path with
+  such bytes. A V4 swap action is read only in the parameter shape deployed on
+  mainnet and Sepolia, not in the newer one on `v4-periphery` `main`, which adds
+  a `minHopPriceX36` field. An action in any other shape is not read, and its
+  step is listed as `V4 Swap (could not be decoded)`. Each step is named and
+  read as the command that the release of the router at that address runs for
+  its command type, as that release's `contracts/libraries/Commands.sol` names
+  it. The decoder reads the type from the command byte with the mask that router
+  uses: `0x1f` for `UniversalRouterV1`, `0x3f` for
+  `UniversalRouterV1_2_V2Support` and `UniversalRouterV2`, and `0x7f` for
+  `UniversalRouterV2_1_1` and `UniversalRouterV2_1_2`. The allow-revert flag
+  (`0x80`) therefore does not change the command a step is read as. Releases run
+  different commands for some types: on `UniversalRouterV1` and
+  `UniversalRouterV1_2_V2Support`, `0x10` to `0x13` are NFT commands, where the
+  later routers run `V4_SWAP`, `V3_POSITION_MANAGER_PERMIT`,
+  `V3_POSITION_MANAGER_CALL` and `V4_INITIALIZE_POOL`. The decoder does not read
+  those routers' NFT commands, and lists each by its name there, for example
+  `Seaport` for `SEAPORT` (`0x10` on `UniversalRouterV1`). A type a release
+  names no command for is listed by its number, for example `Command 0x0e` on
+  `UniversalRouterV1`, which has no `BALANCE_CHECK_ERC20` and reverts on it. The
+  router reverts the whole transaction when a step fails, unless the step's
+  command byte has that flag set and its command is one the router lets fail, as
+  each release's `contracts/base/Dispatcher.sol` shows: on `UniversalRouterV2`,
+  `UniversalRouterV2_1_1` and `UniversalRouterV2_1_2`, `PERMIT2_PERMIT`,
+  `PERMIT2_PERMIT_BATCH`, `BALANCE_CHECK_ERC20`, `V3_POSITION_MANAGER_PERMIT`,
+  `V3_POSITION_MANAGER_CALL`, `V4_INITIALIZE_POOL`, `V4_POSITION_MANAGER_CALL`
+  and `EXECUTE_SUB_PLAN`; on `UniversalRouterV1_2_V2Support`,
+  `BALANCE_CHECK_ERC20`, `EXECUTE_SUB_PLAN` and its NFT market calls and NFT
+  owner checks; on `UniversalRouterV1`, its NFT market calls and NFT owner
+  checks. Such a step may then fail while the transaction goes on to the next
+  step, and it is listed with ` (allowed to fail)` after its name, for example
+  `Balance Check (allowed to fail)`. On every other command, among them each V2,
+  V3 and V4 swap and each payment of ETH or an ERC-20 token, the flag has no
+  effect: the step succeeds or the whole transaction reverts, so the step reads
+  as it does without the flag. A `BALANCE_CHECK_ERC20` the router lets fail
+  guarantees nothing, so it is read as one whose `minBalance` is zero. Only the
+  routers with the `0x7f` mask have `PAY_PORTION_FULL_PRECISION` (`0x07`),
+  listed as `Pay Portion (Full Precision)`, and `ACROSS_V4_DEPOSIT_V3` (`0x40`),
+  listed as `Across Bridge Deposit`; the other routers revert on `0x07`, and it
+  is listed there as `Command 0x07`. The decoder does not read the commands
+  inside an `EXECUTE_SUB_PLAN` (`0x21`) step, and wherever that step stands they
+  may spend the user's tokens or pay the user. That step is listed as
+  `Execute Sub-Plan (its steps are not shown)`, and whatever the other steps
+  state, the summary names no swap direction, `Token In` and `Token Out` read
+  `Unknown (could not be decoded)`, and there is no `Amount` or `Min. received`
+  line. Each swap step, `SWEEP`, `WRAP_ETH`, `UNWRAP_WETH`, `TRANSFER`,
+  `PAY_PORTION`, `PAY_PORTION_FULL_PRECISION`, `PERMIT2_TRANSFER_FROM` (which
+  moves the user's own tokens) and V4 `TAKE` and `TAKE_PORTION` names the
+  address it pays, and `TAKE_ALL` pays the transaction's sender. The router
+  reads `address(1)` as the transaction's sender, and `address(2)` as the router
+  itself, which holds what it is paid until a later step pays it out; a payment
+  to the router, as `address(2)` or by its own address, is not counted as paid
+  out. `UniversalRouterV1` alone pays a `PERMIT2_TRANSFER_FROM` to `address(1)`
+  or `address(2)` as those addresses, and the decoder names them. A
+  `PERMIT2_TRANSFER_FROM` into the router is named with the amount it moves,
+  because the decoder does not check that later steps spend all of it.
+  `ACROSS_V4_DEPOSIT_V3` pays the bridge, which pays the deposit's recipient on
+  another network and refunds a deposit nobody fills to its depositor; the
+  router passes both on as written, so `address(1)` and `address(2)` there are
+  addresses, and each that is not the transaction's sender is named. A
+  `BALANCE_CHECK_ERC20` pays nobody: the router checks that its owner holds at
+  least `minBalance` of its token, and reads the owner as written, so
+  `address(1)` and `address(2)` there are addresses too. A check of any address
+  but the transaction's sender's says nothing about what the user receives: it
+  sets neither `Token Out` nor the minimum, and it is listed as
+  `Balance Check (of another address)`. A check whose input does not decode,
+  such as one whose owner word has a nonzero top byte (the router reads the
+  owner from the word's last 20 bytes), likewise sets neither, and it is listed
+  as `Balance Check (could not be decoded)`. When a swap step, `TAKE` or
+  `TAKE_PORTION` pays the router any token, the swap's output or another, a
+  `WRAP_ETH` pays it WETH, or an `UNWRAP_WETH` into the router turns WETH a step
+  paid it into ETH, that token stays in the router unless a later step pays out
+  or spends all the router holds of it: a `SWEEP` of that token to anyone but
+  the router, an `UNWRAP_WETH` when it is WETH, a `WRAP_ETH` of
+  `CONTRACT_BALANCE` when it is ETH, a `TRANSFER` of `CONTRACT_BALANCE`, a
+  `PAY_PORTION` of 10,000 bips or a `PAY_PORTION_FULL_PRECISION` of 1e18 of that
+  token to anyone but the router, an `ACROSS_V4_DEPOSIT_V3` of
+  `CONTRACT_BALANCE` of that token, or of ETH when it sets `useNative`, or a V2
+  or V3 exact-in swap step or V4 `SETTLE` that pays `CONTRACT_BALANCE` of that
+  token from the router (`payerIsUser` false). V2 and V3 exact-in swap steps and
+  V4 `SETTLE`s that pay WETH from the router also spend all the WETH a
+  `WRAP_ETH` paid it once together they spend the amount the `WRAP_ETH` states,
+  as a swap paid in ETH does, but only when that amount is not
+  `CONTRACT_BALANCE` and the router held no WETH from an earlier step when the
+  `WRAP_ETH` ran: after two `WRAP_ETH`s of 0.5 ETH into the router, a swap of 1
+  WETH from it reads as leaving the WETH there. A V2 or V3 exact-out step paid
+  from the router spends an amount the calldata does not state, at most its
+  `amountInMax`, so the decoder counts it as spending nothing the router holds.
+  A `SETTLE` of `OPEN_DELTA` (zero), and a `SETTLE_ALL`, pay only what the step
+  still owes of their token when they run. The decoder takes that to be the
+  amounts the step's swap actions state they spend of that token only when every
+  action in the step could be read, every swap action names the token it spends
+  and the token it buys (a swap action with an empty path swaps nothing), the
+  `SETTLE` or `SETTLE_ALL` is the step's only `SETTLE` or `SETTLE_ALL` of that
+  token and comes after every swap action, no swap action buys that token, no
+  `TAKE`, `TAKE_ALL` or `TAKE_PORTION` in the step takes it (a `TAKE` of a
+  stated amount adds to what the step owes), and the swap actions that spend it
+  state a quantity together; otherwise it does not know the amount, and such a
+  `SETTLE` from the router counts as spending nothing. So the rest of a V4
+  `SETTLE` of more than its swap spends, taken to the router, the WETH of a
+  `WRAP_ETH`, and a token a swap pays the router on the way to the output, each
+  stays in the router when later steps do not spend all of it, where anyone can
+  take it in a later transaction. The router sends ETH as written, so a
+  `TRANSFER` of `CONTRACT_BALANCE` of ETH always reverts and pays out nothing. A
+  step paying a token to the V2 pair that the very next step spends, as a V2
+  exact-in of that token whose `amountIn` is `ALREADY_PAID` (zero) or
+  `CONTRACT_BALANCE`, is a hop, not a payout: Uniswap's mixed routes pay the
+  next V2 pair directly, and the router enforces that swap's own minimum. The
+  decoder checks that the address paid is that pair, deriving it from the V2
+  factory and pair init code hash the network's routers were deployed with and
+  the first two tokens of that step's path; a payment to any other address is
+  named. (Sepolia's `UniversalRouterV1_2_V2Support` was deployed with
+  placeholders for both values, so no V2 swap step can succeed on that router.)
+  Every other payment counts, in whichever step and of whatever token, a share
+  of the output included: an interface fee paid to another address by
+  `PAY_PORTION`, `TRANSFER` or `TAKE_PORTION` is named, and the minimum reads
+  `Min. paid out`, because the swap's minimum includes the fee. The minimum
+  reads `Min. received` only when some step pays the transaction's sender (the
+  From address on TxApproval, the sender the explorer reports on
+  TransactionDetail) and no `Paid to` line is shown. `Paid to` lines after
+  `Token Out` name each other address paid; one reads
+  `The bridge, which pays the deposit's recipient on another network` for a
+  bridge deposit; one reads, for example,
+  `The router, 2000.0000 USDT from the sender (later steps may not spend all of it)`
+  for each move into the router, followed by a `Token moved into the router`
+  line that gives the moved token's address as the `Token In` line does; one
+  reads `The router, where it stays (no later step pays it out)` for each token
+  that stays in the router, followed, for any token but the output, by a
+  `Token moved into the router` line giving that token in the same way (ETH by
+  name); and one more reads `Unknown (could not be decoded)` when a step that
+  may pay an address went unread. When no step pays anyone, a single line reads
+  `Unknown (not named in the calldata)`. Wherever there is a `Paid to` line, the
+  minimum reads `Min. paid out`. The `Amount` line gives the total the steps
+  take of `Token In`, from the step that sets the input side on: the first V2 or
+  V3 exact-in or exact-out, `WRAP_ETH` or V4 swap step that names an input token
+  or amount. A V4 step with a swap action sets the input side when no earlier
+  step set it, even when it names neither (see Display Consistency). That step
+  counts its own amount, whoever pays it: a V2 or V3 exact-out step its
+  `amountInMax`, and a V4 step what it takes of its input token from the user's
+  wallet, as below, or, when the user pays it none of that token, the `amountIn`
+  of the swap action that spends it. Each later V2 or V3 exact-in or exact-out
+  step whose `payerIsUser` is true takes its amount, found in the same way, from
+  the user's wallet. Every V4 step, with a swap action or without, takes from
+  the user's wallet what its `SETTLE`s paid by the user (`payerIsUser` true) and
+  its `SETTLE_ALL`s pay, for each token on its own; what the step that sets the
+  input side takes of any other token counts as a later step's take. A `SETTLE`
+  of any amount but `OPEN_DELTA` pays that amount, and a `SETTLE` of
+  `OPEN_DELTA` or a `SETTLE_ALL` pays what the step owes, as above. So a V4 step
+  that swaps 400 USDT, with a `SETTLE` of 5,000 USDT paid by the user and the
+  rest taken to another address, reads `5000.0000 USDT`. A later step paid from
+  the router spends what the router holds and takes nothing, and so does a V2
+  exact-in whose `amountIn` is `ALREADY_PAID`. A later take of `Token In` is
+  added to the total while both are quantities: a V3 exact-in of 600 USDT and a
+  V2 exact-in of 400 USDT, both paid by the user, read `1000.0000 USDT`. When
+  the decoder does not know a take's amount, the total is not known and there is
+  no `Amount` line. `Token In` is the token of the last `PERMIT2_PERMIT` the
+  decoder reads, when there is one. Its amount, `Unlimited` included, stands as
+  the `Amount` figure in place of the total only in the plain shape of Uniswap's
+  own routes: it is the only `PERMIT2_PERMIT`, its spender is the router, the
+  router may not let it fail, no step before it takes its token or a token the
+  decoder does not know, and the decoder reads every step after it in full.
+  Permit2 then lets the router take no more of the token than that amount, so
+  the permit covers every take of it. A step the decoder does not read in full
+  may raise what Permit2 lets the router take, as a `PERMIT2_PERMIT_BATCH` can:
+  a command the decoder does not read (listed at the end of this section), a
+  step whose input it cannot read, in whole or in part, and a step it fails on.
+  In any other case the line gives the total, as with no permit. When the step
+  that sets the input side spends a token other than the permit's, or one the
+  decoder does not know, its amount gets lines of its own, unless it states no
+  amount and the user pays it none of its input token, and the total has no
+  figure to start from: unless the permit's amount stands there is no `Amount`
+  line, and each take of the permit's token gets lines of its own. Each take the
+  total does not count gives three lines after the `Amount` line (after
+  `Token In` when there is none): one of a token other than `Token In`; one of
+  `Token In` after an amount that is not a quantity (a V4 open delta,
+  `ALREADY_PAID`, which keep their wording on the `Amount` line, or no stated
+  amount, as of a V4 exact-out step); and one whose amount the decoder does not
+  know. When the step that sets the input side states no amount, the user pays
+  it some of its input token, and there is no `Amount` line, that step gets them
+  too whenever another take's lines give a figure, or a `PERMIT2_TRANSFER_FROM`
+  of its token gives one, on the lines below or, into the router, on its
+  `Paid to` line, so that figure cannot read as all that leaves. When it states
+  no amount and the user pays it none of its input token, as when the router
+  pays it, that step takes none of that token from the user's wallet and never
+  gets them, with a permit or without. They come in step order, the step that
+  sets the input side first when it has them: `Moved from the sender`, its
+  amount, worded as the `Amount` line words one, or
+  `Unknown (could not be decoded)` when the decoder does not know it;
+  `Token moved`, giving the token's address as the `Token In` line does; and
+  `Moved to`, which reads `The swap step that spends it`. A token the decoder
+  does not know gives the `Moved from the sender` line alone. A step may also
+  take from the user's wallet what the decoder did not read: a V4 step whose
+  input or one of whose `SETTLE`s or `SETTLE_ALL`s it cannot read, which the
+  router still runs; a V2 or V3 exact-in or exact-out step or a
+  `PERMIT2_TRANSFER_FROM` whose input it cannot read, such as a V3 step whose
+  path is shorter than one token address or has bytes after its last hop; every
+  `PERMIT2_TRANSFER_FROM_BATCH`; every `EXECUTE_SUB_PLAN`, wherever it stands;
+  and every step it fails on. Each such step gives one `Moved from the sender`
+  line among those, reading `Unknown (could not be decoded)`. That line, or any
+  line for a token the decoder does not know, leaves no `Amount` line, whose
+  figure might be too low, and such a step before a `PERMIT2_PERMIT` keeps the
+  permit's amount from standing. Then each `PERMIT2_TRANSFER_FROM` but one into
+  the router, in step order, gives three lines: `Moved from the sender`, the
+  amount it moves, for example `1000000.0000 USDT`; `Token moved`, giving the
+  token's address as the `Token In` line does; and `Moved to`, which reads
+  `The V2 pair the next swap spends` for a hop and `The sender` for `address(1)`
+  on every router but `UniversalRouterV1`, and otherwise gives the address. A
+  move into the router needs none of them, because its `Paid to` line and
+  `Token moved into the router` line already give the amount, the token and
+  where it goes, and so its amount is shown once. These lines change neither the
+  `Paid to` lines nor the minimum's label. A step goes unread when its recipient
+  does not decode as an address, when it is a V3 swap step whose path is shorter
+  than one token address or has bytes after its last hop, or when it is a
+  command the decoder does not read: every command other than `PERMIT2_PERMIT`,
+  `PERMIT2_TRANSFER_FROM`, `V2_SWAP_EXACT_IN`, `V2_SWAP_EXACT_OUT`,
+  `V3_SWAP_EXACT_IN`, `V3_SWAP_EXACT_OUT`, `V4_SWAP`, `SWEEP`, `TRANSFER`,
+  `PAY_PORTION`, `PAY_PORTION_FULL_PRECISION`, `ACROSS_V4_DEPOSIT_V3`,
+  `WRAP_ETH`, `UNWRAP_WETH` and `BALANCE_CHECK_ERC20`
+  (`PERMIT2_TRANSFER_FROM_BATCH`, `EXECUTE_SUB_PLAN` and the NFT commands among
+  them), or a type its release names no command for.
 
 ### Non-Goals Forever
 

docs/README.md

@@ -306,7 +306,14 @@ enter your password and click "Confirm" to authorize it. Message and typed-data
 signature requests work the same way, with a "Sign" button, and also require
 your password.
 
-If the requesting site's domain is on the phishing blocklist, all three approval
+A connected site can also ask to switch the wallet's network. A popup shows the
+site's origin, the current network and the requested network. Nothing changes
+unless you click "Switch"; clicking "Reject" or closing the popup leaves
+everything as it was. Switching works exactly as it does in Settings, and
+changes the network for the whole wallet and for every site, not only for the
+one that asked.
+
+If the requesting site's domain is on the phishing blocklist, all four approval
 screens show a red phishing warning before you decide.
 
 You can manage site permissions in Settings. Allowed and denied sites can be
@@ -378,7 +385,8 @@ Click the gear icon on the home screen to access settings:
 - **Display**: Toggle whether tracked tokens with zero balance are shown, switch
   timestamps to UTC, and choose the theme (System, Light, or Dark).
 - **Network**: Switch between Ethereum Mainnet and Sepolia Testnet. Switching
-  resets the RPC and Blockscout endpoints to that network's defaults.
+  restores the RPC and Blockscout endpoints you last used on that network, or
+  that network's defaults if you have not used it before.
 - **Ethereum RPC**: Change the Ethereum node endpoint. Default is a public RPC.
   You can use your own node for maximum privacy.
 - **Blockscout API**: Change the Blockscout instance used for token balances and

package.json

@@ -13,6 +13,11 @@
         "fmt": "prettier --write .",
         "fmt-check": "prettier --check ."
     },
+    "jest": {
+        "setupFiles": [
+            "<rootDir>/tests/support/navigatorLocks.js"
+        ]
+    },
     "devDependencies": {
         "@eslint/js": "10.0.1",
         "@tailwindcss/cli": "4.3.1",

src/background/index.js

@@ -1308,6 +1308,12 @@ async function broadcastAccountsChanged() {
         return;
     }
     for (const tab of tabs) {
+        // The tab's URL is all the background knows of the page in it, and a
+        // page at a site's URL may have another origin: a page its server
+        // sandboxes with a Content-Security-Policy has the origin "null". So
+        // the event names the origin it was judged by, and the content script
+        // passes the address on only to a page whose own origin is that one
+        // (src/content/index.js).
         const origin = tab.url ? new URL(tab.url).origin : "";
         const hasPermission =
             activeAddress &&
@@ -1319,6 +1325,7 @@ async function broadcastAccountsChanged() {
             type: "AUTISTMASK_EVENT",
             eventName: "accountsChanged",
             data: hasPermission ? [activeAddress] : [],
+            origin,
         }).catch(() => {});
     }
 }

src/background/state.js

@@ -16,17 +16,20 @@
 //                     across any number of awaits and no concurrent work can
 //                     move it.
 //   updateState(fn)   read fresh, apply fn to that fresh record, write it
-//                     back — all inside a queue, so two background writes
-//                     never interleave, and the read is one storage round trip
-//                     ahead of the write rather than a page lifetime ahead of
-//                     it (which is what made the popup's saveState() need a
+//                     back — all holding the lock every write of the stored
+//                     record takes, so no other write lands in between, by
+//                     the background or by any page except a page in a
+//                     Firefox private window (README, "Stored state and its
+//                     version"). The read is one storage round trip ahead of
+//                     the write rather than a page lifetime ahead of it
+//                     (which is what made the popup's saveState() need a
 //                     per-field merge against a baseline at all).
 //
 // A handler that must both read and write therefore does its network work
 // against a snapshot it owns, and applies the RESULT inside updateState().
 // It never publishes an object other in-flight work is holding.
 
-const { storageGet, storageSet } = require("../shared/browserApi");
+const { storageGet, storageSet, withLock } = require("../shared/browserApi");
 const { normalizePersisted } = require("../shared/persistedState");
 const {
     STATE_SCHEMA_VERSION,
@@ -51,11 +54,6 @@ async function getState() {
     return normalizePersisted(result.autistmask);
 }
 
-// Serializes the read-modify-write turns below. Two of them interleaved would
-// each read before the other wrote, and the second write would carry the first
-// one's fields back to their pre-turn values.
-let updateQueue = Promise.resolve();
-
 async function updateStateOnce(mutate) {
     const s = await getState();
     await mutate(s);
@@ -70,27 +68,22 @@ async function updateStateOnce(mutate) {
 
 // Apply `mutate` to a record read fresh from storage and write the result
 // back. `mutate` receives a detached, normalized profile and mutates it in
-// place; it may be async, but it must not do anything slow — the window
-// between the read and the write is the window in which another context's
-// write is lost, and keeping it to one storage round trip is what makes a
-// whole-record write safe here. Concretely: the write is the WHOLE record, so
-// a popup write that lands inside that window is reverted, in every field, by
-// the record this turn read before it. That is accepted because the window is
-// one round trip long and the popup is not writing while the worker is;
-// widening it is what would make it a real hazard.
+// place; it may be async, but it must not do anything slow. The write is the
+// WHOLE record, which is safe only because the lock (withLock() in
+// src/shared/browserApi.js) is held from the read to the write: two
+// background turns, or a turn and a page's save, never interleave
+// (https://git.eeqj.de/sneak/AutistMask/issues/641). Every page's save waits
+// while it is held, except a page in a Firefox private window, which Firefox
+// gives locks of its own (README, "Stored state and its version").
 //
 // `mutate` must also not call updateState() itself, directly or through
-// anything it awaits: the queue is strictly serial, so the inner turn waits on
-// the outer one, which is waiting on the inner one. That deadlocks the whole
-// background, not just the caller. Mutate the record you were handed.
+// anything it awaits: the inner turn waits for the lock the outer one holds,
+// and the outer one is waiting on the inner one. That deadlocks every write of
+// the stored record, not just the caller. Mutate the record you were handed.
 //
 // Resolves with the record that was written.
 function updateState(mutate) {
-    const turn = updateQueue.then(() => updateStateOnce(mutate));
-    // The queue must advance even when a turn rejects, or every update after
-    // it queues behind a promise that never settles.
-    updateQueue = turn.catch(() => {});
-    return turn;
+    return withLock("autistmask", () => updateStateOnce(mutate));
 }
 
 module.exports = { getState, updateState };

src/content/index.js

@@ -49,14 +49,23 @@ window.addEventListener("message", (event) => {
 
 // Listen for events pushed from the background (e.g. accountsChanged)
 runtimeApi().onMessage.addListener((msg) => {
-    if (msg.type === "AUTISTMASK_EVENT") {
-        window.postMessage(
-            {
-                type: "AUTISTMASK_EVENT",
-                eventName: msg.eventName,
-                data: msg.data,
-            },
-            "*",
-        );
+    if (msg.type !== "AUTISTMASK_EVENT") return;
+    // The background chooses the addresses in accountsChanged for the site
+    // at the origin the event names, which is the origin of the tab's URL.
+    // This page hears them only when its own origin is that one. A page whose
+    // origin has no host is not a site: one its server sandboxes with a
+    // Content-Security-Policy has the origin "null" whatever its URL, and is
+    // told no address, as its requests are refused.
+    let data = msg.data;
+    if (msg.eventName === "accountsChanged" && msg.origin !== window.origin) {
+        data = [];
     }
+    window.postMessage(
+        {
+            type: "AUTISTMASK_EVENT",
+            eventName: msg.eventName,
+            data,
+        },
+        "*",
+    );
 });

src/popup/index.html

@@ -90,7 +90,7 @@
                 <div id="add-wallet-section-mnemonic">
                     <!-- The die button shares the instruction's row: on a row
                          of its own it pushes Import below the fold at
-                         360x600. -->
+                         396x600. -->
                     <div class="mb-2 flex justify-between items-start gap-2">
                         <p>
                             Enter your 12 or 24 word recovery phrase below, or
@@ -212,7 +212,7 @@
                     />
                 </div>
                 <!-- The error line sits beside Import, not above it: at
-                     360x600 the button already starts near the bottom of
+                     396x600 the button already starts near the bottom of
                      the popup, and a line of its own would push it below
                      the fold. The longest error fits on one line here. -->
                 <div class="flex items-center gap-2">
@@ -634,17 +634,12 @@
                     </div>
                 </div>
                 <div id="confirm-warnings" class="mb-2 invisible"></div>
-                <div id="confirm-recipient-warning" class="mb-2 invisible">
-                    <div
-                        class="border border-red-500 border-dashed p-2 text-xs font-bold text-red-500"
-                    >
-                        WARNING: The recipient address has ZERO transaction
-                        history. This may indicate a fresh or unused address.
-                        Double-check the address before sending.
-                    </div>
-                </div>
-                <!-- Its sentence names the network's native token, so show()
-                in confirmTx.js sets it. -->
+                <!-- These two sentences name the network's native token, so
+                show() in confirmTx.js sets them. -->
+                <div
+                    id="confirm-recipient-warning"
+                    class="mb-2 border border-red-500 border-dashed p-2 text-xs font-bold text-red-500 invisible"
+                ></div>
                 <div
                     id="confirm-contract-warning"
                     class="mb-2 border border-red-500 border-dashed p-2 text-xs font-bold text-red-500 invisible"
@@ -669,6 +664,20 @@
                     id="confirm-errors"
                     class="mb-2 border border-border border-dashed p-2 invisible min-h-[1.25rem]"
                 ></div>
+                <!-- Its sentence names the token, or why the token's balance
+                is unknown, so show() in confirmTx.js sets it. -->
+                <div
+                    id="confirm-balance-error"
+                    class="mb-2 border border-border border-dashed p-2 text-xs invisible"
+                ></div>
+                <div
+                    id="confirm-balance-read-error"
+                    class="mb-2 border border-border border-dashed p-2 text-xs invisible"
+                >
+                    Your balance could not be read from the network, so this
+                    transaction cannot be checked against it. Please go back and
+                    try again.
+                </div>
                 <div
                     id="confirm-amount-fee-error"
                     class="mb-2 border border-border border-dashed p-2 text-xs invisible"
@@ -688,6 +697,33 @@
                     id="confirm-fee-unknown-error"
                     class="mb-2 border border-border border-dashed p-2 text-xs invisible"
                 ></div>
+                <!-- Shown when Sign & Send refuses a send for its network, for
+                a From address the selected wallet does not hold, or for its
+                gas limit or fee. Each holds its space from the first paint, so
+                the refusal moves nothing. -->
+                <div
+                    id="confirm-network-changed-error"
+                    class="mb-2 border border-border border-dashed p-2 text-xs invisible"
+                >
+                    The active network changed after this transaction was
+                    reviewed, so it was not sent. Please go back and review it
+                    again.
+                </div>
+                <div
+                    id="confirm-from-address-error"
+                    class="mb-2 border border-border border-dashed p-2 text-xs invisible"
+                >
+                    The selected wallet does not hold the From address above, so
+                    nothing was sent. Please go back and send again.
+                </div>
+                <div
+                    id="confirm-fee-bound-error"
+                    class="mb-2 border border-border border-dashed p-2 text-xs invisible"
+                >
+                    The gas limit or fee the RPC endpoint quoted for this
+                    transaction is more than this wallet will sign for, so it
+                    was not sent. Please go back and try again.
+                </div>
                 <div class="mb-2">
                     <label class="block mb-1 text-xs">Password</label>
                     <input
@@ -843,7 +879,7 @@
                     id="add-token-info"
                     class="text-xs text-muted mb-2 min-h-[1.25rem] invisible"
                 ></div>
-                <div class="mb-2">
+                <div id="add-token-common" class="mb-2">
                     <label class="block mb-1 text-xs text-muted"
                         >Or pick a common token:</label
                     >
@@ -929,9 +965,9 @@
                 <div class="bg-well p-3 mx-1 mb-3">
                     <h3 class="font-bold mb-1">Network</h3>
                     <p class="text-xs text-muted mb-1">
-                        Select the Ethereum network. Switching networks will
-                        update the RPC and Blockscout endpoints to their
-                        defaults.
+                        Select the Ethereum network. Switching restores the RPC
+                        and Blockscout endpoints last used on that network, or
+                        that network's defaults if it has none.
                     </p>
                     <div class="text-xs flex items-center gap-1">
                         <select
@@ -1128,7 +1164,8 @@
                 <p class="text-xs mb-3">
                     Deleting
                     <strong id="delete-wallet-name"></strong> is permanent. Any
-                    funds will be unrecoverable without your recovery phrase.
+                    funds will be unrecoverable without your
+                    <span id="delete-wallet-key-material"></span>.
                 </p>
                 <div class="mb-2">
                     <label class="block mb-1">Password</label>
@@ -1179,13 +1216,13 @@
                     money at its addresses is not moved or destroyed.
                 </p>
                 <p class="text-xs mb-2">
-                    If you have the recovery phrase for this wallet written
-                    down, add the wallet again afterwards with a new password
-                    and you will have it back.
+                    If you have kept a copy of this wallet's
+                    <span id="delete-wallet-lost-key-material"></span>, add the
+                    wallet again afterwards with a new password and you will
+                    have it back.
                     <strong
-                        >If you do not have it written down, deleting this
-                        wallet means losing everything it holds,
-                        forever.</strong
+                        >If you have not, deleting this wallet means losing
+                        everything it holds, forever.</strong
                     >
                 </p>
                 <p class="text-xs mb-3">Your other wallets are not touched.</p>
@@ -1326,36 +1363,39 @@
                 <h2 class="font-bold mb-2">Add Token</h2>
                 <p class="text-xs text-muted mb-3">
                     Pick a common token or enter a contract address manually.
+                    Common tokens are offered on Ethereum Mainnet only.
                 </p>
 
-                <!-- top 10 quick-pick buttons -->
-                <div class="mb-3">
-                    <label class="block mb-1 text-xs text-muted"
-                        >Top tokens:</label
-                    >
-                    <div
-                        id="settings-addtoken-top10"
-                        class="flex flex-wrap gap-1"
-                    ></div>
-                </div>
+                <div id="settings-addtoken-common">
+                    <!-- top 10 quick-pick buttons -->
+                    <div class="mb-3">
+                        <label class="block mb-1 text-xs text-muted"
+                            >Top tokens:</label
+                        >
+                        <div
+                            id="settings-addtoken-top10"
+                            class="flex flex-wrap gap-1"
+                        ></div>
+                    </div>
 
-                <!-- top 100 dropdown -->
-                <div class="mb-3">
-                    <label class="block mb-1 text-xs text-muted"
-                        >Or pick from top 100:</label
-                    >
-                    <select
-                        id="settings-addtoken-select"
-                        class="border border-border p-1 w-full font-mono text-sm bg-bg text-fg"
-                    >
-                        <option value="">-- select --</option>
-                    </select>
-                    <button
-                        id="btn-settings-addtoken-select"
-                        class="border border-border px-2 py-1 mt-1 hover:bg-fg hover:text-bg cursor-pointer"
-                    >
-                        Add selected
-                    </button>
+                    <!-- top 100 dropdown -->
+                    <div class="mb-3">
+                        <label class="block mb-1 text-xs text-muted"
+                            >Or pick from top 100:</label
+                        >
+                        <select
+                            id="settings-addtoken-select"
+                            class="border border-border p-1 w-full font-mono text-sm bg-bg text-fg"
+                        >
+                            <option value="">-- select --</option>
+                        </select>
+                        <button
+                            id="btn-settings-addtoken-select"
+                            class="border border-border px-2 py-1 mt-1 hover:bg-fg hover:text-bg cursor-pointer"
+                        >
+                            Add selected
+                        </button>
+                    </div>
                 </div>
 
                 <!-- manual contract address -->

src/popup/index.js

@@ -64,8 +64,8 @@ window.addEventListener("pagehide", () => pageClosed.abort());
 
 let refreshInFlight = false;
 
-// The ten-second refresh init() starts, stopped when the popup moves to the
-// recovery screen: there is no profile left to refresh.
+// The ten-second refresh startRefresh() starts, stopped when the popup moves to
+// the recovery screen: there is no profile left to refresh.
 let refreshTimer = null;
 
 async function doRefreshAndRender() {
@@ -99,9 +99,23 @@ async function doRefreshAndRender() {
     }
 }
 
+// Refreshes now and every ten seconds from then on. Called once a wallet
+// exists: by init() when the popup opens with one, and by AddWallet when it
+// adds one, which in a popup that opened on Welcome is the first
+// (https://git.eeqj.de/sneak/AutistMask/issues/530). With the refresh already
+// running it starts no second one, and on the recovery screen it does nothing.
+function startRefresh() {
+    if (!$("view-state-recovery").classList.contains("hidden")) return;
+    doRefreshAndRender();
+    if (refreshTimer === null) {
+        refreshTimer = setInterval(doRefreshAndRender, 10000);
+    }
+}
+
 const ctx = {
     renderWalletList,
     doRefreshAndRender,
+    startRefresh,
     pageClosed: pageClosed.signal,
     showAddWalletView: () => {
         pushCurrentView();
@@ -318,8 +332,7 @@ async function init() {
     } else {
         renderWalletList();
         restoreView();
-        doRefreshAndRender();
-        refreshTimer = setInterval(doRefreshAndRender, 10000);
+        startRefresh();
     }
 }
 

src/popup/viewRouter.js

@@ -13,6 +13,7 @@
 // cannot be required outside a browser.
 
 const { RESTORABLE_VIEWS } = require("../shared/restorableViews");
+const { SUPPORTED_CHAIN_IDS } = require("../shared/networks");
 
 // The views this page load has rendered.
 //
@@ -37,9 +38,11 @@ function markViewRendered(view) {
     if (view) renderedViews.add(view);
 }
 
-// Begin a fresh page-load scope. The popup gets one by being loaded; the
+// Begin a fresh page-load scope. The popup gets one by being loaded, and
+// asks for one when the user switches the network, because every screen
+// then on the page shows the previous network (views/settings.js); the
 // unit tests, which simulate several page loads against one module
-// instance, ask for one.
+// instance, ask for one too.
 function resetRenderedViews() {
     renderedViews.clear();
 }
@@ -124,25 +127,33 @@ function isRenderableDecoded(value) {
 }
 
 // The pending transaction confirmTx.show() renders: `token` reaches
-// renderAddressHtml() when it is not "ETH", and `from`/`to` reach
-// addressTitle(), makeBlockie() and getLocalWarnings().
+// renderAddressHtml() when it is not "ETH", `from`/`to` reach
+// addressTitle(), makeBlockie() and getLocalWarnings(), and `amount` reaches
+// truncateAmountNeverZero(), which splits it. `chainId`, which show() fills in
+// when it is absent, picks the network whose explorer the address links open,
+// so it has to name one.
 function isRenderablePendingTx(value) {
     return (
         isRecord(value) &&
         isText(value.token) &&
         isAddressText(value.from) &&
-        isAddressText(value.to)
+        isAddressText(value.to) &&
+        isText(value.amount) &&
+        (!value.chainId || SUPPORTED_CHAIN_IDS.has(value.chainId))
     );
 }
 
 // The stored transaction transactionDetail.render() shows. contractAddress is
 // optional on an ETH transfer, and reaches addressDotHtml() when it is there.
+// `chainId` picks the network whose explorer the links open and whose
+// Blockscout the transaction is read from, so it has to name one.
 function isRenderableTx(value) {
     return (
         isRecord(value) &&
         isAddressText(value.from) &&
         isAddressText(value.to) &&
-        (!value.contractAddress || isAddressText(value.contractAddress))
+        (!value.contractAddress || isAddressText(value.contractAddress)) &&
+        SUPPORTED_CHAIN_IDS.has(value.chainId)
     );
 }
 
@@ -194,11 +205,19 @@ function renderView(view, state, views) {
             if (!data.hash) return false;
             if (!isAddressText(data.to)) return false;
             if (!isRenderableDecoded(data.decoded)) return false;
+            // `chainId` picks the network whose explorer the links open, so
+            // when it is there it has to name one. Likewise on error-tx.
+            if (data.chainId && !SUPPORTED_CHAIN_IDS.has(data.chainId)) {
+                return false;
+            }
             views.txStatus.renderSuccess();
             return true;
         case "error-tx":
             if (!data.message) return false;
             if (!isAddressText(data.to)) return false;
+            if (data.chainId && !SUPPORTED_CHAIN_IDS.has(data.chainId)) {
+                return false;
+            }
             views.txStatus.renderError();
             return true;
         default:
@@ -213,9 +232,10 @@ function renderView(view, state, views) {
 // in the two cases where the view is known to be on the page already:
 //
 //   - It is not one the popup renders from persisted state. The restored
-//     stack is filtered against RESTORABLE_VIEWS, so such a view can only
-//     be on the stack from this page load, where forward navigation
-//     rendered it on the way in.
+//     stack is filtered against RESTORABLE_VIEWS, and a network switch cuts
+//     it the same way (views/settings.js), so such a view can only be on the
+//     stack from this page load, where forward navigation rendered it on the
+//     way in.
 //   - This page load has rendered it. Re-rendering would re-fetch and
 //     clobber what it holds; Home is rendered anyway, see above.
 //

src/popup/views/addToken.js

@@ -1,6 +1,6 @@
 const { $, showView, showFlash, escapeHtml, goBack } = require("./helpers");
 const { getTopTokens } = require("../../shared/tokenList");
-const { state, saveState } = require("../../shared/state");
+const { state, saveState, currentNetwork } = require("../../shared/state");
 const { lookupTokenInfo } = require("../../shared/balances");
 const { isScamAddress } = require("../../shared/scamlist");
 const { log } = require("../../shared/log");
@@ -9,6 +9,12 @@ function show() {
     $("add-token-address").value = "";
     $("add-token-info").textContent = "";
     $("add-token-info").style.visibility = "hidden";
+    // The bundled list holds Ethereum Mainnet contracts, which name no token
+    // on any other network.
+    $("add-token-common").classList.toggle(
+        "hidden",
+        state.networkId !== "mainnet",
+    );
     const list = $("common-token-list");
     list.innerHTML = getTopTokens(25)
         .map(
@@ -46,6 +52,9 @@ function init(ctx) {
         infoEl.textContent = "Looking up token...";
         infoEl.style.visibility = "visible";
         log.debugf("Looking up token contract", contractAddr);
+        // The network the lookup asks, which Settings may switch away from
+        // before it answers, as for a transaction in confirmTx.js.
+        const chainId = currentNetwork().chainId;
         try {
             const info = await lookupTokenInfo(
                 contractAddr,
@@ -53,6 +62,15 @@ function init(ctx) {
                 state.networkId,
                 ctx.pageClosed,
             );
+            // A contract address names a token on one network only, so an
+            // answer after a switch is not added to the new network's list.
+            if (currentNetwork().chainId !== chainId) {
+                showFlash(
+                    "The active network changed before the lookup finished," +
+                        " so the token was not added.",
+                );
+                return;
+            }
             log.infof("Adding token", info.symbol, contractAddr);
             state.trackedTokens.push({
                 address: contractAddr,

src/popup/views/addWallet.js

@@ -234,7 +234,7 @@ async function importMnemonic(ctx) {
         showFlash("Ready.", 1000);
     }
 
-    ctx.doRefreshAndRender();
+    ctx.startRefresh();
 }
 
 async function importPrivateKey(ctx) {
@@ -274,7 +274,7 @@ async function importPrivateKey(ctx) {
     ctx.renderWalletList();
     showView("main");
 
-    ctx.doRefreshAndRender();
+    ctx.startRefresh();
 }
 
 async function importXprvKey(ctx) {
@@ -368,7 +368,7 @@ async function importXprvKey(ctx) {
         showFlash("Ready.", 1000);
     }
 
-    ctx.doRefreshAndRender();
+    ctx.startRefresh();
 }
 
 function init(ctx) {

src/popup/views/approval.js

@@ -11,6 +11,7 @@ const {
     onViewLeave,
     formatFee,
     tokenLabel,
+    tokenSourcesByChainId,
 } = require("./helpers");
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const {
@@ -57,9 +58,15 @@ const { notify, runtimeApi, sendMessage } = require("../../shared/browserApi");
 
 const erc20Iface = new Interface(ERC20_ABI);
 
-function approvalAddressHtml(address) {
+// The link opens the explorer of the network with `chainId`, or of the active
+// network when none is given. A chain id that names no network has no
+// explorer, so the address is drawn without a link.
+function approvalAddressHtml(address, chainId) {
     const title = addressTitle(address, state.wallets);
-    return renderAddressHtml(address, { title });
+    if (chainId && !networkByChainId(chainId)) {
+        return renderAddressHtml(address, { title, noLink: true });
+    }
+    return renderAddressHtml(address, { title, chainId });
 }
 
 // The amount line for a decoded ERC-20 call. With a known scale it is the
@@ -79,18 +86,18 @@ function tokenAmountText(rawAmount, decimals, symbol) {
     };
 }
 
-// Try to decode calldata using known ABIs.
+// Try to decode calldata sent from `fromAddress` to `toAddress` on the network
+// with chain id `chainId`, using known ABIs.
 // Returns { name, description, details } or null.
-function decodeCalldata(data, toAddress) {
+function decodeCalldata(data, toAddress, chainId, fromAddress) {
     if (!data || data === "0x" || data.length < 10) return null;
 
-    // Where a token's scale is looked for, for every decoder below: the ERC-20
-    // amount line and the swap's Amount and Min. received lines resolve it the
-    // same way, and refuse to format the same way when it is nowhere.
-    const decimalsSources = {
-        trackedTokens: state.trackedTokens,
-        wallets: state.wallets,
-    };
+    // Where a token's name and scale are looked for, for every decoder below:
+    // what the wallet knows of the tokens on the network with `chainId`, which
+    // need not be the active one. The ERC-20 amount line and the swap's Amount
+    // and Min. received lines resolve the scale the same way, and refuse to
+    // format the same way when it is nowhere.
+    const decimalsSources = tokenSourcesByChainId(chainId);
 
     // Try ERC-20 (approve / transfer)
     try {
@@ -185,7 +192,13 @@ function decodeCalldata(data, toAddress) {
     }
 
     // Try Uniswap Universal Router
-    const routerResult = uniswap.decode(data, toAddress, decimalsSources);
+    const routerResult = uniswap.decode(
+        data,
+        toAddress,
+        chainId,
+        decimalsSources,
+        fromAddress,
+    );
     if (routerResult) return routerResult;
 
     return null;
@@ -218,10 +231,11 @@ function showTxFee(approvedTx) {
     const feePerGas = BigInt(approvedTx.maxFeePerGas || approvedTx.gasPrice);
     // Through formatFee(), as the confirmation screen's fee is, so the same
     // fee reads the same on both. In the native currency of the network shown
-    // above, as the value is.
+    // above, and at the price on it, as the value is.
     $("approve-tx-fee").textContent = formatFee(
         gasLimit * feePerGas,
         nativeCurrencyByChainId(approvedTx.chainId),
+        approvedTx.chainId,
     );
 
     let detail =
@@ -254,10 +268,7 @@ function showTxApproval(details) {
 
     const toAddr = approvedTx.to;
     const ethValue = formatEther(approvedTx.value || "0");
-    const sources = {
-        trackedTokens: state.trackedTokens,
-        wallets: state.wallets,
-    };
+    const sources = tokenSourcesByChainId(approvedTx.chainId);
 
     // Build txInfo for status screens
     pendingTxDetails = {
@@ -269,8 +280,15 @@ function showTxApproval(details) {
         chainId: approvedTx.chainId,
     };
 
-    // If this is an ERC-20 call, try to extract the real recipient and amount
-    const decoded = decodeCalldata(approvedTx.data, toAddr || "");
+    // If this is an ERC-20 call, try to extract the real recipient and amount.
+    // Decoded for the network the transaction is for, which the Network line
+    // names, and the address the From line names.
+    const decoded = decodeCalldata(
+        approvedTx.data,
+        toAddr || "",
+        approvedTx.chainId,
+        details.approvedFrom,
+    );
     if (decoded && decoded.details) {
         // The asset the status summary is counted in: an ERC-20 call's Token
         // contract, or a swap's input token. Its symbol is resolved from the
@@ -327,27 +345,35 @@ function showTxApproval(details) {
         };
     }
 
+    // Every address link on this screen opens the explorer of the network the
+    // transaction is for, which the Network line names, whichever network is
+    // active.
     $("approve-tx-origin").textContent = details.origin;
-    $("approve-tx-from").innerHTML = approvalAddressHtml(details.approvedFrom);
+    $("approve-tx-from").innerHTML = approvalAddressHtml(
+        details.approvedFrom,
+        approvedTx.chainId,
+    );
 
-    // Show token symbol next to contract address if known
-    const symbol = toAddr ? tokenLabel(toAddr) : null;
+    // Show token symbol next to contract address if known on the network the
+    // transaction is for
+    const symbol = toAddr ? tokenLabel(toAddr, approvedTx.chainId) : null;
     if (toAddr) {
         let toHtml = "";
         if (symbol) {
             toHtml += `<div class="font-bold mb-1">${escapeHtml(symbol)}</div>`;
         }
-        toHtml += approvalAddressHtml(toAddr);
+        toHtml += approvalAddressHtml(toAddr, approvedTx.chainId);
         $("approve-tx-to").innerHTML = toHtml;
     } else {
         $("approve-tx-to").innerHTML = escapeHtml(CONTRACT_CREATION_TEXT);
     }
 
-    const ethValueFormatted = formatTxValue(
-        formatEther(approvedTx.value || "0"),
-    );
-    const ethPrice = getPrice("ETH");
-    const ethUsd = ethPrice ? parseFloat(ethValueFormatted) * ethPrice : null;
+    const ethValueFormatted = formatTxValue(ethValue);
+    // Priced from the exact value, not the four-decimal figure, at the price
+    // on the network the transaction is for, as the confirmation screen prices
+    // its amount, so the same value reads the same on both.
+    const ethPrice = getPrice("ETH", approvedTx.chainId);
+    const ethUsd = ethPrice ? parseFloat(ethValue) * ethPrice : null;
     const usdStr = formatUsd(ethUsd);
     // In the native currency of the network the transaction is for, which the
     // Network line names, not the active network's: the active network can
@@ -374,9 +400,12 @@ function showTxApproval(details) {
             detailsHtml += `<div class="text-muted">${escapeHtml(d.label)}</div>`;
             if (d.address) {
                 if (d.isToken) {
-                    detailsHtml += `<div class="font-bold">${escapeHtml(tokenLabel(d.address) || "Unknown token")}</div>`;
+                    detailsHtml += `<div class="font-bold">${escapeHtml(tokenLabel(d.address, approvedTx.chainId) || "Unknown token")}</div>`;
                 }
-                detailsHtml += approvalAddressHtml(d.address);
+                detailsHtml += approvalAddressHtml(
+                    d.address,
+                    approvedTx.chainId,
+                );
             } else {
                 detailsHtml += `<div class="font-bold">${escapeHtml(d.value)}</div>`;
             }

src/popup/views/confirmTx.js

@@ -23,6 +23,7 @@ const {
     goBack,
     onViewLeave,
     formatFee,
+    reviewedNetworkProvider,
 } = require("./helpers");
 const { state, currentNetwork } = require("../../shared/state");
 const { nativeCurrencyByChainId } = require("../../shared/networks");
@@ -42,8 +43,8 @@ const {
     transferAmountUnits,
 } = require("../../shared/transferAmount");
 const { assertWithinCeilings } = require("../../shared/approvalVerify");
-// The balance lines, the fee reserve and the insufficient-balance messages go
-// through it, as the approval screen's amounts do.
+// The amount, the balance line and the fee reserve go through it, as the
+// approval screen's amounts do.
 const { truncateAmountNeverZero } = require("../../shared/amountDisplay");
 const {
     CODES,
@@ -68,12 +69,11 @@ let feeWei = null;
 // the node at signing time.
 let maxSendFees = null;
 // The From address's balances on the network this screen is drawn for, read
-// from that network's node by readBalances() each time the screen is shown.
-// The popup can reopen onto this screen after the network was switched, so
-// any balance Send knew may be another network's. Null until the read
-// returns; then `eth` and `token` are decimal strings, `token` null for an
-// ETH send or a token whose scale is unknown, and both null if the read
-// failed.
+// from that network's node by readBalances() each time the screen is shown,
+// so a screen the popup reopens onto states them as they are then, not as
+// Send knew them. Null until the read returns; then `eth` and `token` are
+// decimal strings, `token` null for an ETH send or a token whose scale is
+// unknown, and both null if the read failed.
 let balances = null;
 
 function restore() {
@@ -83,11 +83,11 @@ function restore() {
     }
 }
 
-function confirmAddressHtml(address, ensName, title) {
+function confirmAddressHtml(address, ensName, title, chainId) {
     const blockie = blockieHtml(address);
     return (
         `<div class="mb-1">${blockie}</div>` +
-        renderAddressHtml(address, { title, ensName })
+        renderAddressHtml(address, { title, ensName, chainId })
     );
 }
 
@@ -98,17 +98,41 @@ function valueWithUsd(text, usdAmount) {
     return text;
 }
 
-// The Amount line, with its USD value. A max ETH send's line is drawn again
-// once its amount is re-derived from the fee estimate.
+// The amount as this screen and the wait, success and error screens show it,
+// written as the approval screen writes a site's amount: the amount being
+// signed, parsed at the scale it is encoded with and written back as plain
+// decimal text, then cut to four decimals with the nonzero floor. So `.5` and
+// `00.5` read `0.5000`, as `0.5` does, except for a token whose scale is
+// unknown, which cannot be sent: its amount is cut as typed, so `.5` reads
+// `.5000`. txInfo.amount, which is what gets signed, is left as it is.
+function shownAmount(txInfo) {
+    let exact = txInfo.amount;
+    try {
+        if (txInfo.token === "ETH") {
+            exact = formatEther(parseEther(txInfo.amount));
+        } else {
+            const decimals = displayedDecimals(txInfo.tokenDecimals);
+            exact = formatUnits(parseUnits(txInfo.amount, decimals), decimals);
+        }
+    } catch {
+        // A token whose scale is unknown, which is never signed, or an amount
+        // the amount check refuses: cut as Send's amount field held it.
+    }
+    return truncateAmountNeverZero(exact);
+}
+
+// The Amount line, with its USD value, which is priced from the exact amount.
+// A max ETH send's line is drawn again once its amount is re-derived from the
+// fee estimate.
 function renderAmount(txInfo) {
     const isErc20 = txInfo.token !== "ETH";
     const rawSymbol = isErc20
         ? txInfo.tokenSymbol || "?"
         : nativeCurrencyByChainId(txInfo.chainId);
-    const price = isErc20 ? getPrice(rawSymbol) : getPrice("ETH");
+    const price = getPrice(isErc20 ? rawSymbol : "ETH", txInfo.chainId);
     const amountUsd = price ? parseFloat(txInfo.amount) * price : null;
     $("confirm-amount").textContent = valueWithUsd(
-        txInfo.amount + " " + displaySymbol(rawSymbol),
+        shownAmount(txInfo) + " " + displaySymbol(rawSymbol),
         amountUsd,
     );
 }
@@ -133,7 +157,7 @@ function renderBalance(txInfo) {
         $("confirm-balance").textContent = "unknown (" + symbol + ")";
         return;
     }
-    const price = isErc20 ? getPrice(rawSymbol) : getPrice("ETH");
+    const price = getPrice(isErc20 ? rawSymbol : "ETH", txInfo.chainId);
     const balUsd = price ? parseFloat(bal) * price : null;
     $("confirm-balance").textContent = valueWithUsd(
         truncateAmountNeverZero(bal) + " " + symbol,
@@ -147,14 +171,15 @@ function show(txInfo) {
     feeWei = null;
     maxSendFees = null;
     balances = null;
-    // The network this screen is drawn for, and the only one it sends on:
-    // Settings can switch the active network while the screen is open. This
-    // screen and the wait, success and error screens label amounts by it.
-    txInfo.chainId = currentNetwork().chainId;
-    // That network's node, read here once and passed to every read below, so
-    // a read still in flight when the network is switched, and the fee
-    // estimate that follows the balance read, stay on it.
-    const provider = getProvider(state.rpcUrl, state.networkId);
+    // The network this screen is drawn for, and the only one it sends on: the
+    // one active when Send handed the transaction over. Drawn again from the
+    // saved transaction, as when the popup reopens onto this screen, it keeps
+    // that network, so Sign & Send refuses once Settings has switched to
+    // another. Everything this screen shows is that network's: native
+    // currency, USD values, explorer links, the balance, and the node and
+    // explorer its checks ask. The wait, success and error screens label
+    // amounts by it.
+    if (!txInfo.chainId) txInfo.chainId = currentNetwork().chainId;
 
     const isErc20 = txInfo.token !== "ETH";
     // The raw symbol is the price-table key; the capped one is what the
@@ -178,7 +203,7 @@ function show(txInfo) {
     if (isErc20) {
         $("confirm-token-contract").innerHTML = renderAddressHtml(
             txInfo.token,
-            {},
+            { chainId: txInfo.chainId },
         );
         tokenSection.classList.remove("hidden");
         attachCopyHandlers(tokenSection);
@@ -192,6 +217,7 @@ function show(txInfo) {
         txInfo.from,
         null,
         fromTitle,
+        txInfo.chainId,
     );
 
     // To (with blockie)
@@ -200,6 +226,7 @@ function show(txInfo) {
         txInfo.to,
         txInfo.ensName,
         toTitle,
+        txInfo.chainId,
     );
     $("confirm-to-ens").classList.add("hidden");
 
@@ -243,7 +270,14 @@ function show(txInfo) {
         nativeCurrencyByChainId(txInfo.chainId) +
         " to this address and try again.";
 
-    // Shown later, once checkRecipientHistory() finds a contract.
+    // Both shown later, by checkRecipientHistory(). The first sentence says
+    // exactly what getFullWarnings() checks.
+    $("confirm-recipient-warning").textContent =
+        "WARNING: The recipient address has never sent a transaction and" +
+        " holds no " +
+        nativeCurrencyByChainId(txInfo.chainId) +
+        ". This may indicate a fresh or unused address. Double-check the" +
+        " address before sending.";
     $("confirm-contract-warning").textContent =
         "WARNING: The recipient is a smart contract. Sending " +
         nativeCurrencyByChainId(txInfo.chainId) +
@@ -263,11 +297,29 @@ function show(txInfo) {
               " cannot be checked against your balance. Please go back and" +
               " try again.";
 
+    // So does the message for an amount the balance does not cover. It is
+    // set here, before the first paint, so the balance read returning only
+    // makes it visible and moves nothing, which is why it quotes no balance.
+    // Without the token's scale readBalances() reads no token balance.
+    $("confirm-balance-error").textContent =
+        isErc20 && toDecimals(txInfo.tokenDecimals) === null
+            ? "This token's balance is unknown, because nothing this wallet" +
+              " can consult reports how many decimal places it uses, so the" +
+              " amount you are trying to send cannot be checked against it."
+            : "Your " +
+              symbol +
+              " balance does not cover this amount. Please go back and send" +
+              " a smaller amount.";
+
     renderValidation(txInfo);
 
-    // Reset password field and error
+    // Reset password field and error, and any refusal of an earlier Sign &
+    // Send.
     $("confirm-tx-password").value = "";
     hideError("confirm-tx-password-error");
+    setVisible("confirm-network-changed-error", false);
+    setVisible("confirm-from-address-error", false);
+    setVisible("confirm-fee-bound-error", false);
 
     // Gas estimate — show placeholder then fetch async
     $("confirm-fee").style.visibility = "visible";
@@ -290,17 +342,18 @@ function show(txInfo) {
 
     // The fee is estimated once the balances are read, because a max ETH
     // send's amount is the ETH balance minus the estimate's reserve.
-    readBalances(txInfo, provider).then(() => estimateGas(txInfo, provider));
-    checkRecipientHistory(txInfo, provider);
+    readBalances(txInfo).then(() => estimateGas(txInfo));
+    checkRecipientHistory(txInfo);
 }
 
-// Read the From address's balances from `provider`, the node of the network
-// this screen is drawn for: ETH, and for a token send the token, at the scale
-// the screen renders the amount with. A token whose scale is unknown has no
-// balance to read. Never rejects.
-async function readBalances(txInfo, provider) {
+// Read the From address's balances from the node of the network this
+// transaction was reviewed for: ETH, and for a token send the token, at the
+// scale the screen renders the amount with. A token whose scale is unknown has
+// no balance to read. Never rejects.
+async function readBalances(txInfo) {
     let read;
     try {
+        const provider = reviewedNetworkProvider(txInfo);
         const decimals = toDecimals(txInfo.tokenDecimals);
         const readToken = txInfo.token !== "ETH" && decimals !== null;
         const [ethWei, tokenUnits] = await Promise.all([
@@ -332,13 +385,11 @@ async function readBalances(txInfo, provider) {
 // re-running it never moves anything.
 function renderValidation(txInfo) {
     const isErc20 = txInfo.token !== "ETH";
-    const symbol = isErc20
-        ? displaySymbol(txInfo.tokenSymbol || "?")
-        : nativeCurrencyByChainId(txInfo.chainId);
 
     // Null while the balances are being read and after a read that failed.
     // validateTransfer() takes a missing balance as nothing to spend from, so
-    // sending stays blocked either way, and no message below quotes one.
+    // sending stays blocked either way, and the only message shown for it is
+    // the one saying the read failed.
     const ethBalance = balances ? balances.eth : null;
     const tokenBalance = balances ? balances.token : null;
     const balanceRead = ethBalance !== null;
@@ -353,53 +404,14 @@ function renderValidation(txInfo) {
         feeWei,
     });
 
-    // Messages carrying the user's own numbers are built here; the fixed
-    // sentences live in the reserved elements in index.html, except the
-    // gas and fee-unknown ones, which show() sets.
+    // An invalid amount is known before the first paint, so its message is
+    // written here. Every message a later result brings has a reserved
+    // element, its sentence fixed in index.html or set by show(), and is only
+    // made visible below, so nothing moves when the result arrives.
     const messages = [];
     if (codes.includes(CODES.AMOUNT_INVALID)) {
         messages.push("Please enter a valid amount to send.");
     }
-    if (balances !== null && !balanceRead) {
-        messages.push(
-            "Your balance could not be read from the network, so this" +
-                " transaction cannot be checked against it. Please go back" +
-                " and try again.",
-        );
-    }
-    if (balanceRead && codes.includes(CODES.INSUFFICIENT_TOKEN)) {
-        messages.push(
-            tokenBalance == null
-                ? "This token's balance is unknown, because nothing this" +
-                      " wallet can consult reports how many decimal places it" +
-                      " uses, so the amount you are trying to send cannot be" +
-                      " checked against it."
-                : "Insufficient " +
-                      symbol +
-                      " balance. You have " +
-                      truncateAmountNeverZero(tokenBalance) +
-                      " " +
-                      symbol +
-                      " but are trying to send " +
-                      txInfo.amount +
-                      " " +
-                      symbol +
-                      ".",
-        );
-    }
-    if (balanceRead && codes.includes(CODES.INSUFFICIENT_ETH)) {
-        messages.push(
-            "Insufficient balance. You have " +
-                truncateAmountNeverZero(ethBalance) +
-                " " +
-                symbol +
-                " but are trying to send " +
-                txInfo.amount +
-                " " +
-                symbol +
-                ".",
-        );
-    }
 
     const errorsEl = $("confirm-errors");
     if (messages.length > 0) {
@@ -412,6 +424,13 @@ function renderValidation(txInfo) {
         errorsEl.style.visibility = "hidden";
     }
 
+    setVisible("confirm-balance-read-error", balances !== null && !balanceRead);
+    setVisible(
+        "confirm-balance-error",
+        balanceRead &&
+            (codes.includes(CODES.INSUFFICIENT_TOKEN) ||
+                codes.includes(CODES.INSUFFICIENT_ETH)),
+    );
     setVisible(
         "confirm-amount-fee-error",
         balanceRead && codes.includes(CODES.INSUFFICIENT_ETH_WITH_FEE),
@@ -437,10 +456,9 @@ function setVisible(id, visible) {
     $(id).style.visibility = visible ? "visible" : "hidden";
 }
 
-// Estimate the network fee on `provider`, the node of the network this screen
-// is drawn for.
-async function estimateGas(txInfo, provider) {
+async function estimateGas(txInfo) {
     try {
+        const provider = reviewedNetworkProvider(txInfo);
         const feeData = await provider.getFeeData();
         let gasLimit;
 
@@ -489,7 +507,11 @@ async function estimateGas(txInfo, provider) {
         if (estimateWei !== null && estimateWei < gasCostWei) {
             $("confirm-fee-amount").textContent =
                 "~" +
-                formatFee(estimateWei, nativeCurrencyByChainId(txInfo.chainId));
+                formatFee(
+                    estimateWei,
+                    nativeCurrencyByChainId(txInfo.chainId),
+                    txInfo.chainId,
+                );
             $("confirm-fee-reserve").textContent =
                 "up to " +
                 truncateAmountNeverZero(formatEther(gasCostWei)) +
@@ -504,6 +526,7 @@ async function estimateGas(txInfo, provider) {
             $("confirm-fee-amount").textContent = formatFee(
                 gasCostWei,
                 nativeCurrencyByChainId(txInfo.chainId),
+                txInfo.chainId,
             );
             setVisible("confirm-fee-reserve", false);
         }
@@ -545,16 +568,17 @@ async function estimateGas(txInfo, provider) {
     }
 }
 
-// Populate the transaction this send describes, enforce the fee bound against
-// the fees that were actually filled in, then sign and broadcast it. Apart
-// from a max ETH send, which passes its estimate's fee fields as `fees`, the
-// send pins no fee fields, so ethers fills maxFeePerGas and the gas limit from
-// what the configured RPC node answers, with nothing otherwise bounding what a
-// hostile node can set — the dApp path's ceilings never reached this one.
-// Populating before the check is what makes assertWithinCeilings() see the
-// same numbers that would be signed; it throws an ApprovalMismatchError when
-// the product gasLimit × maxFeePerGas is over the bound, which the caller
-// shows in the reserved error area rather than sending.
+// Populate the transaction this send describes, enforce the bounds against the
+// gas limit and fees that were actually filled in, then sign and broadcast it.
+// Apart from a max ETH send, which passes its estimate's fee fields as `fees`,
+// the send pins no fee fields, so ethers fills maxFeePerGas and the gas limit
+// from what the configured RPC node answers, with nothing otherwise bounding
+// what a hostile node can set — the dApp path's ceilings never reached this
+// one. Populating before the check is what makes assertWithinCeilings() see
+// the same numbers that would be signed; it throws an ApprovalMismatchError
+// when the gas limit, a fee per gas, or the product gasLimit × maxFeePerGas is
+// over its bound, and the caller then shows the one refusal reserved for all
+// three rather than sending.
 async function populateVerifyAndSend(connectedSigner, tx, fees = null) {
     let request;
     if (tx.token === "ETH") {
@@ -582,20 +606,16 @@ async function populateVerifyAndSend(connectedSigner, tx, fees = null) {
     return connectedSigner.sendTransaction(populated);
 }
 
-// Show a full-sentence send failure in the reserved errors box, the same
-// element and markup renderValidation() uses for messages carrying the user's
-// own numbers, so it never moves anything on the screen.
-function showSendError(message) {
-    const el = $("confirm-errors");
-    el.innerHTML = `<div class="text-xs">${escapeHtml(message)}</div>`;
-    el.style.visibility = "visible";
-}
-
-async function checkRecipientHistory(txInfo, provider) {
+async function checkRecipientHistory(txInfo) {
     try {
+        const provider = reviewedNetworkProvider(txInfo);
         const asyncWarnings = await getFullWarnings(txInfo.to, provider, {
             fromAddress: txInfo.from,
+            chainId: txInfo.chainId,
         });
+        // The user may have left this transaction while the checks were in
+        // flight; its warnings must not reach another recipient's screen.
+        if (pendingTx !== txInfo) return;
         for (const w of asyncWarnings) {
             if (w.type === "contract") {
                 $("confirm-contract-warning").style.visibility = "visible";
@@ -624,6 +644,11 @@ function init(_ctx) {
     onViewLeave("confirm-tx", clearPassword);
 
     $("btn-confirm-send").addEventListener("click", async () => {
+        // A press shows only its own refusal, if any.
+        setVisible("confirm-network-changed-error", false);
+        setVisible("confirm-from-address-error", false);
+        setVisible("confirm-fee-bound-error", false);
+
         const wallet = state.wallets[state.selectedWallet];
         // Every Send button refuses a defective wallet before this screen,
         // but the popup also reopens onto it from a saved view.
@@ -633,14 +658,12 @@ function init(_ctx) {
             return;
         }
 
-        // Back from Settings only unhides this screen, still drawn for the
-        // network that was active when it was shown.
+        // The screen describes the network the transaction was reviewed for,
+        // which Settings may have switched away from since: "Back" from
+        // Settings after a switch draws this screen again from the saved
+        // transaction, as a popup reopened onto it does.
         if (currentNetwork().chainId !== pendingTx.chainId) {
-            showSendError(
-                "The active network changed after this transaction was" +
-                    " reviewed, so it was not sent. Please go back and review" +
-                    " it again.",
-            );
+            setVisible("confirm-network-changed-error", true);
             return;
         }
 
@@ -649,11 +672,7 @@ function init(_ctx) {
         // address selected.
         const addr = wallet.addresses.find((a) => a.address === pendingTx.from);
         if (!addr) {
-            showError(
-                "confirm-tx-password-error",
-                "The selected wallet does not hold the From address above, " +
-                    "so nothing was sent. Please go back and send again.",
-            );
+            setVisible("confirm-from-address-error", true);
             return;
         }
 
@@ -685,6 +704,10 @@ function init(_ctx) {
         $("btn-confirm-send").disabled = true;
         $("btn-confirm-send").classList.add("text-muted");
 
+        // The wait, success and error screens show the amount as this screen
+        // does, so they are handed a copy carrying that text. pendingTx keeps
+        // the exact amount, which is the one signed.
+        const shownTx = { ...pendingTx, amount: shownAmount(pendingTx) };
         let tx;
         try {
             const signer = getSignerForAddress(wallet, addr, decryptedSecret);
@@ -701,19 +724,23 @@ function init(_ctx) {
             // Note: JS strings are immutable; this nulls the reference but
             // the original string may persist in memory until GC.
             decryptedSecret = null;
-            txStatus.showWait(pendingTx, tx.hash);
+            txStatus.showWait(shownTx, tx.hash);
         } catch (e) {
             decryptedSecret = null;
-            // A fee over the bound is refused before anything is broadcast, so
-            // there is no transaction that may have reached the network to warn
-            // about: the message stays on the confirmation screen where the
-            // user can go back, rather than routing to the sent/failed screen.
+            // A gas limit or fee over its bound is refused before anything is
+            // broadcast, so there is no transaction that may have reached the
+            // network to warn about: the refusal stays on the confirmation
+            // screen where the user can go back, rather than routing to the
+            // sent/failed screen. Its sentence is fixed in index.html, so that
+            // its box can hold its space from the first paint; the reason in
+            // full, naming the bound, is logged.
             if (e && e.approvalMismatch) {
-                showSendError(e.message);
+                log.errorf("send refused:", e.message);
+                setVisible("confirm-fee-bound-error", true);
                 return;
             }
             const hash = tx ? tx.hash : null;
-            txStatus.showError(pendingTx, hash, e.shortMessage || e.message);
+            txStatus.showError(shownTx, hash, e.shortMessage || e.message);
         } finally {
             $("btn-confirm-send").disabled = false;
             $("btn-confirm-send").classList.remove("text-muted");

src/popup/views/deleteAddress.js

@@ -17,9 +17,9 @@ const {
     attachCopyHandlers,
     addressHoldsFunds,
     balanceLinesForAddress,
+    keyMaterialName,
 } = require("./helpers");
 const { formatAddressTotal, getAddressValue } = require("../../shared/prices");
-const { walletHasRecoveryPhrase } = require("../../shared/wallet");
 const { state, saveState } = require("../../shared/state");
 const {
     canRemoveAddress,
@@ -54,9 +54,7 @@ function setFlash(msg) {
 // The noun follows the wallet: an xprv wallet holds no recovery phrase, and
 // this screen is offered on xprv wallets too.
 function recoveryPathText(wallet) {
-    const secret = walletHasRecoveryPhrase(wallet)
-        ? "recovery phrase"
-        : "extended private key";
+    const secret = keyMaterialName(wallet);
     return (
         "Getting the address back into this list is not easy, so be sure. " +
         "Adding an address derives the next unused one, not this one, and " +

src/popup/views/deleteWallet.js

@@ -7,6 +7,7 @@ const {
     goBack,
     clearViewStack,
     onViewLeave,
+    keyMaterialName,
 } = require("./helpers");
 const { state, saveState } = require("../../shared/state");
 const { decryptWithPassword } = require("../../shared/vault");
@@ -75,6 +76,9 @@ function show(walletIdx) {
     clear();
     deleteWalletIndex = walletIdx;
     $("delete-wallet-name").textContent = displayName(walletIdx);
+    $("delete-wallet-key-material").textContent = keyMaterialName(
+        state.wallets[walletIdx],
+    );
     showView("delete-wallet-confirm");
 }
 
@@ -94,6 +98,9 @@ function showLostPassword() {
     clearLostPassword();
     $("delete-wallet-lost-name").textContent = name;
     $("delete-wallet-lost-name-echo").textContent = name;
+    $("delete-wallet-lost-key-material").textContent = keyMaterialName(
+        state.wallets[walletIdx],
+    );
     // showView() runs the leave hook of delete-wallet-confirm, which nulls
     // deleteWalletIndex, so this screen's own selection is recorded after
     // it and not before.

src/popup/views/helpers.js

@@ -1,4 +1,7 @@
-// Shared DOM helpers used by all views.
+// Helpers the views in this directory share: showing a view and going back,
+// error and flash lines and the warning banners, formatting of amounts, fees,
+// balances, addresses and dates, the RPC and Blockscout URLs, node and tokens
+// of the network a chain id names, explorer links, and click-to-copy.
 //
 // Escaping rule for every view in this directory, since they all build
 // markup by concatenation: any VALUE interpolated into an innerHTML string
@@ -19,12 +22,15 @@ const {
     isBelowOneMillionth,
 } = require("../../shared/amountDisplay");
 const { resolveTokenSymbol } = require("../../shared/approvalAmount");
+const { getProvider } = require("../../shared/balances");
 const { DEBUG } = require("../../shared/constants");
 const { escapeHtml } = require("../../shared/html");
 const { isDebug } = require("../../shared/log");
+const { networkByChainId } = require("../../shared/networks");
 const { formatUsd, getPrice } = require("../../shared/prices");
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const { displaySymbol } = require("../../shared/symbolDisplay");
+const { walletHasRecoveryPhrase } = require("../../shared/wallet");
 const { markViewRendered } = require("../viewRouter");
 
 // When views are added, removed, or transitions between them change,
@@ -126,7 +132,8 @@ function showView(name) {
 }
 
 // Create or update the debug/insecure warning banner.
-// Called on every view switch and after the settings debug toggle changes.
+// Called on every view switch, after the settings debug toggle changes, and
+// after a network switch in Settings.
 // The banner is shown when the compile-time DEBUG constant is true OR when
 // the user has enabled runtime debug mode via the settings easter egg, OR
 // when the active network is a testnet.
@@ -283,34 +290,51 @@ function unknownableAmount(balance) {
 
 // The active network's native token symbol, `ETH` on mainnet and `SepoliaETH`
 // on Sepolia, as src/shared/networks.js names it. The wallet's balances and
-// the Send and confirmation screens, which send on the active network, label a
-// native amount with this; a transaction already made or requested is labelled
-// by its own chain id, through nativeCurrencyByChainId() in networks.js. The
-// "ETH" that state.selectedToken and txInfo.token hold is the native token's
-// id, not its label, and stays "ETH" on every network.
+// the Send screen, which sends on the active network, label a native amount
+// with this; the confirmation screen, and a transaction already made or
+// requested, label it by the transaction's own chain id, through
+// nativeCurrencyByChainId() in networks.js. The "ETH" that state.selectedToken
+// and txInfo.token hold is the native token's id, not its label, and stays
+// "ETH" on every network.
 function nativeCurrency() {
     return currentNetwork().nativeCurrency;
 }
 
-// The symbol shown for a token line, resolved from the bundled list, the
-// tokens the user tracks, and the explorer's report — the same chain the
-// amount line's scale comes from. Null when no source names one, so the token
-// lines keep saying `Unknown token` for a token nothing knows.
-function tokenLabel(address) {
-    return resolveTokenSymbol(address, {
-        trackedTokens: state.trackedTokens,
-        wallets: state.wallets,
-    });
+// What the wallet knows of the tokens on the network with this chain id, or
+// on the active network when no chain id is given, as the `sources` that
+// resolveTokenSymbol() and resolveTokenDecimals() take. A contract address
+// names a token on one network only, and every token balance held is the
+// active network's, so another network gets the tokens tracked on it
+// (state.networkTrackedTokens, see applyChainSwitchFields()) and no balances.
+function tokenSourcesByChainId(chainId) {
+    const net = chainId ? networkByChainId(chainId) : currentNetwork();
+    if (net && net.id === state.networkId) {
+        return { trackedTokens: state.trackedTokens, wallets: state.wallets };
+    }
+    return {
+        trackedTokens: (net && state.networkTrackedTokens[net.id]) || [],
+        wallets: [],
+    };
+}
+
+// The symbol shown for a token line on the network with `chainId`, or on the
+// active network when none is given: from the bundled list, the tokens the
+// user tracks, and the explorer's report, the sources the amount line's scale
+// comes from. Null when no source names one, so the token lines keep saying
+// `Unknown token` for a token nothing knows.
+function tokenLabel(address, chainId) {
+    return resolveTokenSymbol(address, tokenSourcesByChainId(chainId));
 }
 
 // A network fee in wei as the confirmation and approval screens both show it:
 // the ETH figure through truncateAmountNeverZero() and labelled `symbol`, the
 // native currency of the network the fee is paid on, then its USD value when
-// the ETH price is known. The USD value is of the exact fee, not of the
-// truncated figure.
-function formatFee(wei, symbol) {
+// the ETH price is known on the network with `chainId`, or on the active
+// network when no chain id is given. The USD value is of the exact fee, not of
+// the truncated figure.
+function formatFee(wei, symbol, chainId) {
     const eth = formatEther(wei);
-    const ethPrice = getPrice("ETH");
+    const ethPrice = getPrice("ETH", chainId);
     const usd = ethPrice ? formatUsd(parseFloat(eth) * ethPrice) : "";
     return (
         truncateAmountNeverZero(eth) +
@@ -418,6 +442,16 @@ function addressHoldsFunds(addr) {
     return false;
 }
 
+// The name of a wallet's key material, which is also its only backup: the
+// recovery phrase of an HD wallet, the private key of a key wallet, the
+// extended private key of an xprv wallet. DeleteWallet,
+// DeleteWalletLostPassword and DeleteAddress name the backup with it.
+function keyMaterialName(wallet) {
+    if (walletHasRecoveryPhrase(wallet)) return "recovery phrase";
+    if (wallet.type === "key") return "private key";
+    return "extended private key";
+}
+
 // The fewest characters of an address any caller may ask to display. The
 // 10-character cap inside truncateMiddle() is the other half of the same
 // guarantee; this is the half that used to be spelled out at each call
@@ -592,18 +626,44 @@ const EXT_ICON =
     `<path d="M7 1.5h3.5V5M7 5.5L10.5 1.5"/>` +
     `</svg></span>`;
 
-// Block-explorer URLs. The origin is a per-network constant from
-// src/shared/networks.js; only the path segment is data, and it comes out
-// of explorer JSON (a transaction's from/to, a token's address_hash), which
-// nothing upstream validates as hex. percent-encoding it keeps a segment
-// that contains a slash, a query or a fragment from re-pointing the link
-// somewhere else in the explorer.
-function explorerUrl(kind, value) {
-    return `${currentNetwork().explorerUrl}/${kind}/${encodeURIComponent(value)}`;
+// The RPC and Blockscout URLs Settings has for the network with this chain id,
+// which need not be the active one: ConfirmTx, WaitTx and TransactionDetail
+// use the network their transaction's chain id names, and the popup can reopen
+// onto them after Settings switched the network. The active network's are
+// state.rpcUrl and state.blockscoutUrl, any other's the ones remembered for it,
+// or its defaults (see applyChainSwitchFields()).
+function endpointsByChainId(chainId) {
+    const net = networkByChainId(chainId);
+    if (net.id === state.networkId) {
+        return { rpcUrl: state.rpcUrl, blockscoutUrl: state.blockscoutUrl };
+    }
+    const remembered = state.networkEndpoints[net.id] || {};
+    return {
+        rpcUrl: remembered.rpcUrl || net.defaultRpcUrl,
+        blockscoutUrl: remembered.blockscoutUrl || net.defaultBlockscoutUrl,
+    };
 }
 
-function etherscanAddressUrl(address) {
-    return explorerUrl("address", address);
+// The node of the network a transaction was reviewed for.
+function reviewedNetworkProvider(txInfo) {
+    const net = networkByChainId(txInfo.chainId);
+    return getProvider(endpointsByChainId(txInfo.chainId).rpcUrl, net.id);
+}
+
+// Block-explorer URLs. The origin is a per-network constant from
+// src/shared/networks.js, the explorer of the network with `chainId`, or of
+// the active network when no chain id is given; only the path segment is
+// data, and it comes out of explorer JSON (a transaction's from/to, a token's
+// address_hash), which nothing upstream validates as hex. percent-encoding it
+// keeps a segment that contains a slash, a query or a fragment from
+// re-pointing the link somewhere else in the explorer.
+function explorerUrl(kind, value, chainId) {
+    const network = chainId ? networkByChainId(chainId) : currentNetwork();
+    return `${network.explorerUrl}/${kind}/${encodeURIComponent(value)}`;
+}
+
+function etherscanAddressUrl(address, chainId) {
+    return explorerUrl("address", address, chainId);
 }
 
 // The URL still has to be escaped on the way into href="...": encoding
@@ -669,16 +729,18 @@ function attachCopyHandlers(container) {
 //              with them, and the "at least 32 characters" guarantee has
 //              to survive having no current callers to be a guarantee.
 //   noLink   — if true, omit etherscan link
+//   chainId  — the network whose explorer the link opens; the active
+//              network's when absent
 //
 // After inserting the returned HTML into the DOM, call
 // attachCopyHandlers() on the parent to wire up click-to-copy.
 function renderAddressHtml(address, opts) {
-    const { title, ensName, maxLen, noLink } = opts || {};
+    const { title, ensName, maxLen, noLink, chainId } = opts || {};
     const dot = addressDotHtml(address);
     const displayAddr = maxLen
         ? truncateMiddle(address, Math.max(ADDRESS_MIN_DISPLAY_LEN, maxLen))
         : address;
-    const link = etherscanAddressUrl(address);
+    const link = etherscanAddressUrl(address, chainId);
     const extLink = noLink ? "" : etherscanLinkHtml(link);
 
     let html = "";
@@ -725,8 +787,10 @@ module.exports = {
     balanceLine,
     balanceLinesForAddress,
     addressHoldsFunds,
+    keyMaterialName,
     unknownableAmount,
     nativeCurrency,
+    tokenSourcesByChainId,
     tokenLabel,
     formatFee,
     addressDotHtml,
@@ -742,6 +806,8 @@ module.exports = {
     attachCopyHandlers,
     etherscanLinkHtml,
     explorerUrl,
+    endpointsByChainId,
+    reviewedNetworkProvider,
     EXT_ICON,
     truncateMiddle,
     isoDate,

src/popup/views/settings.js

@@ -16,6 +16,8 @@ const {
 } = require("../dustThreshold");
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const { onChainSwitch } = require("../../shared/chainSwitch");
+const { restorableStack } = require("../../shared/persistedState");
+const { resetRenderedViews, markViewRendered } = require("../viewRouter");
 const {
     log,
     debugFetch,
@@ -319,12 +321,35 @@ function init(ctx) {
     networkSelect.addEventListener("change", async () => {
         const newId = networkSelect.value;
         if (newId === state.networkId) return;
+        // The screens beneath Settings show the previous network, so Back
+        // finds them as it does in a reopened popup: each is rendered again
+        // when Back lands on it, and the stack is cut at the first one that
+        // cannot be rendered from saved state, such as Send or AddToken. It
+        // is cut at AddressToken too, unless that shows the native token: any
+        // other token there was picked on the previous network. Without a
+        // wallet the stack starts at Welcome, which that cut would drop, and
+        // Welcome shows nothing from a network. The cut comes before the
+        // switch so that the switch's save keeps it for a popup closed
+        // straight after.
+        if (state.hasWallet) {
+            const tokenView = state.viewStack.indexOf("address-token");
+            if (tokenView !== -1 && state.selectedToken !== "ETH") {
+                state.viewStack = state.viewStack.slice(0, tokenView);
+            }
+            state.viewStack = restorableStack(state.viewStack, "settings");
+        }
         const net = await onChainSwitch(newId);
         // Open pages are told by the background, as after a site's approved
         // switch request.
         notify({ type: "AUTISTMASK_NETWORK_CHANGED", chainId: net.chainId });
+        resetRenderedViews();
+        // Settings itself, and the testnet banner above it, are brought up
+        // to date for the new network here.
+        markViewRendered("settings");
         $("settings-rpc").value = state.rpcUrl;
         $("settings-blockscout").value = state.blockscoutUrl;
+        renderTrackedTokens();
+        updateDebugBanner(state.currentView);
         showFlash("Switched to " + net.name + ".");
     });
 

src/popup/views/settingsAddToken.js

@@ -1,6 +1,6 @@
 const { $, showView, showFlash, escapeHtml, goBack } = require("./helpers");
 const { getTopTokens } = require("../../shared/tokenList");
-const { state, saveState } = require("../../shared/state");
+const { state, saveState, currentNetwork } = require("../../shared/state");
 const { lookupTokenInfo } = require("../../shared/balances");
 const { isScamAddress } = require("../../shared/scamlist");
 const { log } = require("../../shared/log");
@@ -75,6 +75,12 @@ function show() {
     $("settings-addtoken-address").value = "";
     $("settings-addtoken-info").textContent = "";
     $("settings-addtoken-info").style.visibility = "hidden";
+    // The bundled list holds Ethereum Mainnet contracts, which name no token
+    // on any other network.
+    $("settings-addtoken-common").classList.toggle(
+        "hidden",
+        state.networkId !== "mainnet",
+    );
     renderTop10();
     renderDropdown();
     showView("settings-addtoken");
@@ -130,6 +136,9 @@ function init(_ctx) {
         infoEl.textContent = "Looking up token...";
         infoEl.style.visibility = "visible";
         log.debugf("Looking up token contract", addr);
+        // The network the lookup asks, which Settings may switch away from
+        // before it answers, as for a transaction in confirmTx.js.
+        const chainId = currentNetwork().chainId;
         try {
             const info = await lookupTokenInfo(
                 addr,
@@ -137,6 +146,15 @@ function init(_ctx) {
                 state.networkId,
                 ctx.pageClosed,
             );
+            // A contract address names a token on one network only, so an
+            // answer after a switch is not added to the new network's list.
+            if (currentNetwork().chainId !== chainId) {
+                showFlash(
+                    "The active network changed before the lookup finished," +
+                        " so the token was not added.",
+                );
+                return;
+            }
             log.infof("Adding token", info.symbol, addr);
             state.trackedTokens.push({
                 address: addr,

src/popup/views/stateRecovery.js

@@ -24,7 +24,11 @@
 // than written again locally so that tests/popupElementIds.test.js sees these
 // lookups and holds every id below against the markup.
 const { $, VIEWS } = require("./helpers");
-const { storageGet, storageRemove } = require("../../shared/browserApi");
+const {
+    storageGet,
+    storageRemove,
+    withLock,
+} = require("../../shared/browserApi");
 const { log } = require("../../shared/log");
 
 // Typed in full before anything is erased, in the same spirit as the wallet
@@ -137,7 +141,9 @@ async function resetProfile() {
         return;
     }
     try {
-        await storageRemove("autistmask");
+        // Under the lock every write of the stored record takes, so the erase
+        // cannot land between another write's read and its write and be undone.
+        await withLock("autistmask", () => storageRemove("autistmask"));
     } catch (e) {
         log.errorf("state recovery: reset failed:", e);
         setFlash("The saved data could not be erased. Nothing was changed.");

src/popup/views/transactionDetail.js

@@ -18,6 +18,7 @@ const {
     copyableHtml,
     etherscanLinkHtml,
     explorerUrl,
+    endpointsByChainId,
     displaySymbol,
     goBack,
 } = require("./helpers");
@@ -48,16 +49,16 @@ function getTransactionType(tx) {
     return "Native " + nativeCurrencyByChainId(tx.chainId) + " Transfer";
 }
 
-function txAddressHtml(address, ensName, title) {
+function txAddressHtml(address, ensName, title, chainId) {
     const blockie = blockieHtml(address);
     return (
         `<div class="mb-1">${blockie}</div>` +
-        renderAddressHtml(address, { title, ensName })
+        renderAddressHtml(address, { title, ensName, chainId })
     );
 }
 
-function txHashHtml(hash) {
-    const link = explorerUrl("tx", hash);
+function txHashHtml(hash, chainId) {
+    const link = explorerUrl("tx", hash, chainId);
     const extLink = etherscanLinkHtml(link);
     return copyableHtml(hash, "break-all") + extLink;
 }
@@ -83,10 +84,11 @@ function show(tx) {
             method: tx.method || null,
             contractAddress: tx.contractAddress || null,
             // The network the history entry was read from. The type line and
-            // the fee are in its native currency, not the active network's:
-            // the active network can change, in Settings or when the user
-            // approves a site's request, before a later popup shows this
-            // screen again.
+            // the fee are in its native currency, not the active network's,
+            // the links open its explorer, and the block, network details and
+            // calldata are read from its Blockscout: the active network can
+            // change, in Settings or when the user approves a site's request,
+            // before a later popup shows this screen again.
             chainId: tx.chainId,
         },
     };
@@ -96,18 +98,24 @@ function show(tx) {
 function render() {
     const tx = state.viewData.tx;
     if (!tx) return;
-    $("tx-detail-hash").innerHTML = txHashHtml(tx.hash);
+    $("tx-detail-hash").innerHTML = txHashHtml(tx.hash, tx.chainId);
 
     const fromTitle = addressTitle(tx.from, state.wallets);
     $("tx-detail-from").innerHTML = txAddressHtml(
         tx.from,
         tx.fromEns,
         fromTitle,
+        tx.chainId,
     );
     // 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);
+        $("tx-detail-to").innerHTML = txAddressHtml(
+            tx.to,
+            tx.toEns,
+            toTitle,
+            tx.chainId,
+        );
     } else {
         $("tx-detail-to").innerHTML = escapeHtml(CONTRACT_CREATION_TEXT);
     }
@@ -146,7 +154,7 @@ function render() {
     if (tokenContractSection && tokenContractEl) {
         if (tx.contractAddress) {
             const dot = addressDotHtml(tx.contractAddress);
-            const link = explorerUrl("token", tx.contractAddress);
+            const link = explorerUrl("token", tx.contractAddress, tx.chainId);
             // Hand-rolled rather than renderAddressHtml() because the
             // link goes to the explorer's /token/ page, not /address/.
             // Same two-row shape though: dot and link on the strip, the
@@ -204,7 +212,11 @@ function showDetailField(sectionId, contentId, value) {
 function populateOnChainDetails(txData, chainId) {
     // Block number
     if (txData.block_number != null) {
-        const blockLink = explorerUrl("block", String(txData.block_number));
+        const blockLink = explorerUrl(
+            "block",
+            String(txData.block_number),
+            chainId,
+        );
         const blockSection = $("tx-detail-block-section");
         const blockEl = $("tx-detail-block");
         if (blockSection && blockEl) {
@@ -301,8 +313,9 @@ async function loadFullTxDetails(txHash, chainId) {
     if (!section || !actionEl || !detailsEl) return;
 
     try {
+        const { blockscoutUrl } = endpointsByChainId(chainId);
         const resp = await debugFetch(
-            state.blockscoutUrl + "/transactions/" + txHash,
+            blockscoutUrl + "/transactions/" + txHash,
         );
         if (!resp.ok) return;
         const txData = await resp.json();
@@ -316,7 +329,14 @@ async function loadFullTxDetails(txHash, chainId) {
         // Decoded against the address the transaction was sent to, as the
         // explorer reports it, not the history entry's `to`: for a token
         // transfer that is the transfer's recipient, not the token contract.
-        const decoded = decodeCalldata(inputData, txData.to?.hash || "");
+        // On the network the transaction was sent on, whose Blockscout was
+        // just asked, and from the sender it reports.
+        const decoded = decodeCalldata(
+            inputData,
+            txData.to?.hash || "",
+            chainId,
+            txData.from?.hash || "",
+        );
         if (decoded) {
             // Render decoded calldata matching approval view style
             actionEl.textContent = decoded.name;
@@ -333,9 +353,9 @@ async function loadFullTxDetails(txHash, chainId) {
                     if (tokenSymbol) {
                         detailsHtml += `<div class="font-bold">${escapeHtml(displaySymbol(tokenSymbol))}</div>`;
                     }
-                    detailsHtml += renderAddressHtml(d.address);
+                    detailsHtml += renderAddressHtml(d.address, { chainId });
                 } else if (d.address) {
-                    detailsHtml += renderAddressHtml(d.address);
+                    detailsHtml += renderAddressHtml(d.address, { chainId });
                 } else {
                     detailsHtml += `<div class="font-bold">${escapeHtml(d.value)}</div>`;
                 }

src/popup/views/txStatus.js

@@ -14,10 +14,13 @@ const {
     displaySymbol,
     clearViewStack,
     tokenLabel,
+    reviewedNetworkProvider,
 } = require("./helpers");
 const { state } = require("../../shared/state");
-const { nativeCurrencyByChainId } = require("../../shared/networks");
-const { getProvider } = require("../../shared/balances");
+const {
+    SUPPORTED_CHAIN_IDS,
+    nativeCurrencyByChainId,
+} = require("../../shared/networks");
 const { log } = require("../../shared/log");
 
 // Receipt poll cadence and the deadline after which the wait is reported as
@@ -61,21 +64,22 @@ function endWait() {
 }
 
 // A contract creation reaches these screens with `to` as "" (approval.js
-// writes `to: toAddr || ""`).
-function toAddressHtml(address) {
+// writes `to: toAddr || ""`). The links below open the explorer of the network
+// with `chainId`, or of the active network when none is given.
+function toAddressHtml(address, chainId) {
     if (!address) return escapeHtml(CONTRACT_CREATION_TEXT);
     const title = addressTitle(address, state.wallets);
-    return renderAddressHtml(address, { title });
+    return renderAddressHtml(address, { title, chainId });
 }
 
-function txHashHtml(hash) {
-    const link = explorerUrl("tx", hash);
+function txHashHtml(hash, chainId) {
+    const link = explorerUrl("tx", hash, chainId);
     return copyableHtml(hash, "break-all") + etherscanLinkHtml(link);
 }
 
-function blockNumberHtml(blockNumber) {
+function blockNumberHtml(blockNumber, chainId) {
     const num = String(blockNumber);
-    const link = explorerUrl("block", num);
+    const link = explorerUrl("block", num, chainId);
     return copyableHtml(num) + etherscanLinkHtml(link);
 }
 
@@ -91,9 +95,11 @@ function startWait(txInfo, txHash, broadcastTime, pollNow) {
     // native currency of txInfo.chainId, the network the transaction was sent
     // on, not the active network's: the active network can change, in
     // Settings or when the user approves a site's request, while this screen
-    // is open or before a later popup resumes it. A null token is a swap whose
-    // amount was not decoded (see showTxApproval() in approval.js): the amount
-    // says so, and no symbol follows it.
+    // is open or before a later popup resumes it. The links on all three
+    // screens open that network's explorer, and this screen's receipt is
+    // asked of that network's node, for the same reason. A null token is a
+    // swap whose amount was not decoded (see showTxApproval() in
+    // approval.js): the amount says so, and no symbol follows it.
     let symbol = "";
     if (txInfo.token === "ETH") {
         symbol = nativeCurrencyByChainId(txInfo.chainId);
@@ -102,8 +108,8 @@ function startWait(txInfo, txHash, broadcastTime, pollNow) {
     }
     $("wait-tx-summary").textContent =
         txInfo.amount + (symbol ? " " + symbol : "");
-    $("wait-tx-to").innerHTML = toAddressHtml(txInfo.to);
-    $("wait-tx-hash").innerHTML = txHashHtml(txHash);
+    $("wait-tx-to").innerHTML = toAddressHtml(txInfo.to, txInfo.chainId);
+    $("wait-tx-hash").innerHTML = txHashHtml(txHash, txInfo.chainId);
     attachCopyHandlers("view-wait-tx");
 
     // Persisted so closing and reopening the popup resumes this wait
@@ -128,7 +134,7 @@ function startWait(txInfo, txHash, broadcastTime, pollNow) {
         renderElapsed();
     }, 1000);
 
-    const provider = getProvider(state.rpcUrl, state.networkId);
+    const provider = reviewedNetworkProvider(txInfo);
     let consecutiveFailures = 0;
 
     async function poll() {
@@ -207,10 +213,11 @@ function showWait(txInfo, txHash) {
 // an object merely missing one of them throws a TypeError out of
 // restoreView() — which init() does not guard, skipping the rest of popup
 // init and leaving wait-tx on screen with no back control. A non-numeric
-// broadcastTime leaves an unexitable wait counting "NaNs". txInfo.token,
-// txInfo.tokenSymbol and txInfo.chainId are deliberately unchecked: they are
-// compared and coalesced rather than dereferenced, and tokenSymbol is null for
-// ETH.
+// broadcastTime leaves an unexitable wait counting "NaNs". txInfo.chainId picks
+// the node the receipt is asked of and the explorer the links open, so it has
+// to name a network. txInfo.token and txInfo.tokenSymbol are deliberately
+// unchecked: they are compared and coalesced rather than dereferenced, and
+// tokenSymbol is null for ETH.
 function restoreWait() {
     const d = state.viewData;
     if (!d || !d.pendingWait) return false;
@@ -226,6 +233,7 @@ function restoreWait() {
     // path itself created.
     if (typeof info.to !== "string") return false;
     if (typeof info.amount !== "string") return false;
+    if (!SUPPORTED_CHAIN_IDS.has(info.chainId)) return false;
     if (typeof w.broadcastTime !== "number" || !isFinite(w.broadcastTime)) {
         return false;
     }
@@ -250,12 +258,13 @@ function showSuccess(txInfo, txHash, blockNumber) {
         hash: txHash,
         blockNumber: blockNumber,
         decoded: txInfo.decoded || null,
+        chainId: txInfo.chainId,
     };
     renderSuccess();
     ctx.doRefreshAndRender();
 }
 
-function decodedDetailsHtml(decoded) {
+function decodedDetailsHtml(decoded, chainId) {
     if (!decoded || !decoded.details) return "";
     let html = `<div class="border border-border border-dashed p-2 mb-3">`;
     if (decoded.name) {
@@ -271,11 +280,11 @@ function decodedDetailsHtml(decoded) {
         html += `<div class="text-xs text-muted mb-1">${escapeHtml(d.label)}</div>`;
         if (d.address) {
             if (d.isToken) {
-                const sym = tokenLabel(d.address) || "Unknown token";
+                const sym = tokenLabel(d.address, chainId) || "Unknown token";
                 html += `<div class="font-bold">${escapeHtml(sym)}</div>`;
-                html += toAddressHtml(d.address);
+                html += toAddressHtml(d.address, chainId);
             } else {
-                html += toAddressHtml(d.address);
+                html += toAddressHtml(d.address, chainId);
             }
         } else {
             html += `<div class="font-bold">${escapeHtml(d.value)}</div>`;
@@ -304,16 +313,16 @@ function renderSuccess() {
         toSection.classList.remove("hidden");
         $("success-tx-summary").textContent =
             d.amount + (d.symbol ? " " + d.symbol : "");
-        $("success-tx-to").innerHTML = toAddressHtml(d.to);
+        $("success-tx-to").innerHTML = toAddressHtml(d.to, d.chainId);
     }
 
-    $("success-tx-block").innerHTML = blockNumberHtml(d.blockNumber);
-    $("success-tx-hash").innerHTML = txHashHtml(d.hash);
+    $("success-tx-block").innerHTML = blockNumberHtml(d.blockNumber, d.chainId);
+    $("success-tx-hash").innerHTML = txHashHtml(d.hash, d.chainId);
 
     // Show decoded calldata details if present
     const decodedEl = $("success-tx-decoded");
     if (decodedEl && hasDecoded) {
-        decodedEl.innerHTML = decodedDetailsHtml(d.decoded);
+        decodedEl.innerHTML = decodedDetailsHtml(d.decoded, d.chainId);
         decodedEl.classList.remove("hidden");
     } else if (decodedEl) {
         decodedEl.classList.add("hidden");
@@ -339,6 +348,7 @@ function showError(txInfo, txHash, message) {
         to: txInfo.to,
         hash: txHash || null,
         message: message,
+        chainId: txInfo.chainId,
     };
     renderError();
 }
@@ -348,11 +358,11 @@ function renderError() {
     if (!d || !d.message) return;
     $("error-tx-summary").textContent =
         d.amount + (d.symbol ? " " + d.symbol : "");
-    $("error-tx-to").innerHTML = toAddressHtml(d.to);
+    $("error-tx-to").innerHTML = toAddressHtml(d.to, d.chainId);
     $("error-tx-message").textContent = d.message;
 
     if (d.hash) {
-        $("error-tx-hash").innerHTML = txHashHtml(d.hash);
+        $("error-tx-hash").innerHTML = txHashHtml(d.hash, d.chainId);
         $("error-tx-hash-section").classList.remove("hidden");
         attachCopyHandlers("view-error-tx");
     } else {

src/shared/addressWarnings.js

@@ -51,12 +51,15 @@ function getLocalWarnings(address, options = {}) {
 
 /**
  * Check an address against local lists AND via RPC queries.
- * Async — performs network calls to check contract status and tx history.
+ * Async — performs network calls to check contract status, tx count and
+ * balance.
  *
  * @param {string} address - The target address to check.
  * @param {object} provider - An ethers.js provider instance.
  * @param {object} [options] - Optional context.
  * @param {string} [options.fromAddress] - Sender address (for self-send check).
+ * @param {string} [options.chainId] - Chain id of the network whose explorer
+ *   the Etherscan label check asks; the active network's when omitted.
  * @returns {Promise<Array<{type: string, message: string, severity: string}>>}
  */
 async function getFullWarnings(address, provider, options = {}) {
@@ -78,21 +81,30 @@ async function getFullWarnings(address, provider, options = {}) {
         log.errorf("contract check failed:", e.shortMessage || e.message);
     }
 
-    // Skip tx count check for contracts — they may legitimately have
-    // zero inbound EOA transactions.
+    // The transaction count is the number of transactions the address has
+    // sent, so an address that has only ever received has a count of zero.
+    // Native token it received stays in its balance until it sends a
+    // transaction, so the warning also needs a zero balance. A contract is
+    // skipped: it has its own warning above.
     if (!isContract) {
         try {
             const txCount = await provider.getTransactionCount(address);
             if (txCount === 0) {
-                warnings.push({
-                    type: "new-address",
-                    message:
-                        "This address has never sent a transaction. Double-check it is correct.",
-                    severity: "info",
-                });
+                const balance = await provider.getBalance(address);
+                if (balance === 0n) {
+                    warnings.push({
+                        type: "new-address",
+                        message:
+                            "This address has never sent a transaction and holds none of the network's native token. Double-check it is correct.",
+                        severity: "info",
+                    });
+                }
             }
         } catch (e) {
-            log.errorf("tx count check failed:", e.shortMessage || e.message);
+            log.errorf(
+                "tx count or balance check failed:",
+                e.shortMessage || e.message,
+            );
         }
     }
 
@@ -100,7 +112,10 @@ async function getFullWarnings(address, provider, options = {}) {
     // Runs for ALL addresses including contracts, since many dangerous
     // flagged addresses on Etherscan (drainers, phishing contracts) are contracts.
     try {
-        const etherscanWarning = await checkEtherscanLabel(address);
+        const etherscanWarning = await checkEtherscanLabel(
+            address,
+            options.chainId,
+        );
         if (etherscanWarning) {
             warnings.push(etherscanWarning);
         }

src/shared/browserApi.js

@@ -31,6 +31,11 @@
 // Everything is resolved on use rather than captured at module load. The MV3
 // service worker is torn down and re-evaluated repeatedly, and the unit
 // suite installs its stubs on `global.chrome` around a require().
+//
+// The module also holds withLock(), a wrapper around the browser's
+// `navigator.locks`, which is in neither namespace. It sits beside
+// storageGet() and storageSet() because every write of the stored record
+// takes it.
 
 // The extension API namespace, preferring `browser.*` where it exists.
 //
@@ -219,6 +224,33 @@ function storageRemove(keys) {
     return Promise.resolve(storage.remove(keys));
 }
 
+/**
+ * Run `fn` while holding the browser's lock called `name`
+ * (`navigator.locks`), and settle as `fn` settles. Every page of the extension
+ * and its background share these locks, except a page in a Firefox private
+ * window (README, "Stored state and its version"), so while one of them holds
+ * `name` another asking for it waits, in the order they asked. The lock is let
+ * go when `fn` settles, whether it resolved or rejected.
+ *
+ * Every write of the stored record holds the lock named after its key,
+ * "autistmask", from its read to its write: saveState() in
+ * src/shared/state.js, updateState() in src/background/state.js, and the
+ * reset in src/popup/views/stateRecovery.js.
+ *
+ * @param {string} name
+ * @param {function(): Promise<*>} fn
+ * @returns {Promise<*>} what `fn` resolved with.
+ * @throws rejects, without running `fn`, where `navigator.locks` is absent.
+ */
+function withLock(name, fn) {
+    if (typeof navigator === "undefined" || !navigator.locks) {
+        return Promise.reject(
+            new Error("navigator.locks is not available in this context"),
+        );
+    }
+    return navigator.locks.request(name, () => fn());
+}
+
 // `storage.session`, the browser's session storage: what is kept there lasts
 // until the browser closes. It survives the background worker being stopped
 // and started again, which module-level variables do not (README, Background
@@ -373,4 +405,5 @@ module.exports = {
     windowsGetLastFocused,
     windowsRemove,
     windowsUpdate,
+    withLock,
 };

src/shared/chainSwitchFields.js

@@ -38,6 +38,16 @@ function applyChainSwitchFields(s, newNetworkId) {
         blockscoutUrl: s.blockscoutUrl,
     };
     const remembered = s.networkEndpoints[net.id] || {};
+
+    // Tracked tokens are kept per network the same way, because a contract
+    // address names a token on one network only. s.trackedTokens stays the
+    // active network's list, so nothing that reads it changes: the outgoing
+    // list is put away under its network, and the incoming network's list, or
+    // an empty one, takes its place.
+    if (!s.networkTrackedTokens) s.networkTrackedTokens = {};
+    s.networkTrackedTokens[s.networkId] = s.trackedTokens;
+    s.trackedTokens = s.networkTrackedTokens[net.id] || [];
+
     s.networkId = net.id;
     s.rpcUrl = remembered.rpcUrl || net.defaultRpcUrl;
     s.blockscoutUrl = remembered.blockscoutUrl || net.defaultBlockscoutUrl;

src/shared/etherscanLabels.js

@@ -2,6 +2,8 @@
 // Extension users make the requests directly to Etherscan — no proxy needed.
 // This is a best-effort enrichment: network failures return null silently.
 
+const { networkByChainId } = require("./networks");
+
 // Patterns in the page title that indicate a flagged address.
 // Title format: "Fake_Phishing184810 | Address: 0x... | Etherscan"
 const PHISHING_LABEL_PATTERNS = [/^Fake_Phishing/i, /^Phish:/i, /^Exploiter/i];
@@ -72,18 +74,21 @@ function parseEtherscanPage(html) {
  * Returns a warning object if the address is flagged, or null.
  * Network failures return null silently (best-effort check).
  *
- * Uses the current network's explorer URL so the lookup works on both
- * mainnet (etherscan.io) and Sepolia (sepolia.etherscan.io).
+ * Uses the explorer of the network with `chainId`, or of the active network
+ * when it is omitted: etherscan.io on mainnet, sepolia.etherscan.io on
+ * Sepolia.
  *
  * @param {string} address - Ethereum address to check.
+ * @param {string} [chainId] - Chain id of the network to look it up on.
  * @returns {Promise<{type: string, message: string, severity: string}|null>}
  */
-async function checkEtherscanLabel(address) {
+async function checkEtherscanLabel(address, chainId) {
     try {
         // Lazy require to avoid pulling in chrome.storage at module scope
         // (which breaks unit tests that only exercise parseEtherscanPage).
         const { currentNetwork } = require("./state");
-        const etherscanBase = currentNetwork().explorerUrl + "/address/";
+        const network = chainId ? networkByChainId(chainId) : currentNetwork();
+        const etherscanBase = network.explorerUrl + "/address/";
         const resp = await fetch(etherscanBase + address, {
             headers: { Accept: "text/html" },
         });

src/shared/persistedState.js

@@ -23,6 +23,11 @@ const DEFAULT_STATE = {
     hasWallet: false,
     wallets: [],
     trackedTokens: [],
+    // Tracked tokens remembered per network: { [networkId]: [token, ...] }.
+    // trackedTokens above is the active network's list; this is what the
+    // others are restored from when the active network changes. See
+    // applyChainSwitchFields().
+    networkTrackedTokens: {},
     networkId: "mainnet",
     rpcUrl: DEFAULT_RPC_URL,
     blockscoutUrl: DEFAULT_BLOCKSCOUT_URL,
@@ -289,6 +294,20 @@ function normalizePersisted(saved) {
     // profile whose wallets are perfectly fine. An empty list is a legitimate
     // value and survives.
     out.trackedTokens = structuredClone(tokenRefs(saved.trackedTokens));
+    // Each remembered list is floored like trackedTokens, because
+    // applyChainSwitchFields() puts it straight back onto trackedTokens when
+    // its network becomes the active one. A key that is not a network in
+    // networks.js is dropped, which also keeps an own "__proto__" key from
+    // reaching the plain assignment below.
+    out.networkTrackedTokens = {};
+    if (isRecord(saved.networkTrackedTokens)) {
+        for (const netId of Object.keys(saved.networkTrackedTokens)) {
+            if (!isKnownNetworkId(netId)) continue;
+            out.networkTrackedTokens[netId] = structuredClone(
+                tokenRefs(saved.networkTrackedTokens[netId]),
+            );
+        }
+    }
     // The loud refusal for an unknown id is assertStateUsable(); this is the
     // floor under it. networkId is an object KEY into networkEndpoints below,
     // so a value that is not a network in networks.js must never get that far

src/shared/prices.js

@@ -2,6 +2,7 @@
 
 const { getTopTokenPrices } = require("./tokenList");
 const { isBelowOneMillionth } = require("./amountDisplay");
+const { networkByChainId } = require("./networks");
 
 const PRICE_CACHE_TTL = 300000; // 5 minutes
 
@@ -36,10 +37,13 @@ function clearPrices() {
     lastFetchedAt = 0;
 }
 
-// Return the USD price for a symbol, or null on testnet / unknown.
-function getPrice(symbol) {
+// Return the USD price for a symbol on the network with `chainId`, or on the
+// active network when no chain id is given; null on testnet, on a chain id
+// that names no network, or for a symbol with no price.
+function getPrice(symbol, chainId) {
     const { currentNetwork } = require("./state");
-    if (currentNetwork().isTestnet) return null;
+    const network = chainId ? networkByChainId(chainId) : currentNetwork();
+    if (!network || network.isTestnet) return null;
     return prices[symbol] || null;
 }
 

src/shared/state.js

@@ -35,16 +35,18 @@ const {
     migrationNeeded,
 } = require("./stateSchema");
 
-const { storageGet, storageSet } = require("./browserApi");
+const { storageGet, storageSet, withLock } = require("./browserApi");
 const { log } = require("./log");
 
 // The live record the proxy below guards. Everything inside this module reads
 // and writes THIS object, never the proxy: the guard is for callers.
 const rawState = {
     ...DEFAULT_STATE,
-    // Its own object, not the one DEFAULT_STATE holds: applyChainSwitchFields()
-    // mutates this map in place, and a spread copies the reference.
+    // Their own objects, not the ones DEFAULT_STATE holds:
+    // applyChainSwitchFields() mutates these maps in place, and a spread copies
+    // the reference.
     networkEndpoints: {},
+    networkTrackedTokens: {},
     currentView: null,
     selectedWallet: null,
     selectedAddress: null,
@@ -438,12 +440,14 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 //
 // Every other persisted field stays a whole-field diff:
 // `trackedTokens`/`fraudContracts`/`viewStack` are arrays of scalars with no
-// per-element identity to merge by; `tokenHolderCache` is a map shaped like
-// the ones above, but nothing in src/ ever writes an entry into it — it is
-// only ever reset wholesale to `{}` (applyChainSwitchFields()) — so there is
-// no in-place mutation for a whole-field diff to collide with; `viewData` is
-// this page's own UI scratch space, not data another page has any reason to
-// share membership of.
+// per-element identity to merge by; `networkTrackedTokens` is diffed whole like
+// `trackedTokens` and `networkId`, the two fields a network switch moves
+// together with it; `tokenHolderCache` is a map shaped like the ones above,
+// but nothing in src/ ever writes an entry into it — it is only ever reset
+// wholesale to `{}` (applyChainSwitchFields()) — so there is no in-place
+// mutation for a whole-field diff to collide with; `viewData` is this page's
+// own UI scratch space, not data another page has any reason to share
+// membership of.
 //
 // This does not make two pages that both change the SAME leaf concurrently
 // safe: last write wins on that one leaf, same as before. What it removes
@@ -454,8 +458,8 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 // This page's own live `state` is deliberately NOT rehydrated from a field
 // another page changed — only the record written to storage is merged.
 // showView() fires saveState() on every navigation without awaiting it,
-// which is what makes the queue above necessary in the first place, and a
-// save that is slow to come back has no way to tell whether the field it
+// which is why saves from one page wait for each other (see saveState()), and
+// a save that is slow to come back has no way to tell whether the field it
 // is about to hand back is still the current answer or has since been
 // overtaken by something this very page did in the meantime; writing it
 // into `state` regardless reintroduced exactly the clobber this function
@@ -531,29 +535,15 @@ async function saveStateOnce() {
     baseline = current;
 }
 
-// showView() calls saveState() on every navigation without awaiting it, so
-// two saves from the SAME page can be in flight at once — e.g. a screen
-// shown, then immediately replaced before the first save's storageGet()
-// round trip has come back. Left concurrent, the first save's turn would
-// finish after the second's live-state mutation and then re-hydrate `state`
-// from what IT read, stomping the second, later change back to a stale
-// value — the same clobber this function exists to prevent, just between
-// two saves on one page instead of two pages. Queuing makes every save's
-// snapshot-diff-write-rehydrate run start to finish before the next one
-// begins, so each one only ever sees the true live state at its turn.
-let saveQueue = Promise.resolve();
-
 // Where a failed save is REPORTED, set once by the context that has a screen
 // to say it on (src/popup/index.js).
 //
 // A save that fails must not fail silently. showView() fires saveState() on
-// every navigation without awaiting it, and the queue below has to attach a
-// rejection handler to keep advancing — so a failing save was swallowed
-// entirely: no throw, no message, nothing on screen. The wallet kept running
-// against storage that was rejecting every write, which is the data-loss half
-// of https://git.eeqj.de/sneak/AutistMask/issues/362. The awaited callers were
-// no better off: `await saveState()` inside an unguarded event handler surfaces
-// in the console and nowhere the user looks.
+// every navigation without awaiting it, and `await saveState()` inside an
+// unguarded event handler is no better: either way, without this, a failure
+// would reach only the console, where the user never looks, and the wallet
+// would keep running against storage that rejects every write. That is the
+// data-loss half of https://git.eeqj.de/sneak/AutistMask/issues/362.
 //
 // This is the "tell the user" half; the other half is the floor in
 // normalizePersisted(), which stops the malformed-record cause from arising in
@@ -579,11 +569,20 @@ function reportSaveFailure(err) {
     }
 }
 
+// Each save runs start to finish holding the lock every write of the stored
+// record takes (withLock() in src/shared/browserApi.js), so no write by
+// another page or the background lands between its read and its write and is
+// lost (https://git.eeqj.de/sneak/AutistMask/issues/641). A page in a Firefox
+// private window is the exception: Firefox gives it locks of its own (README,
+// "Stored state and its version").
+//
+// The same lock orders this page's own saves. showView() calls saveState() on
+// every navigation without awaiting it, so two saves from one page can be
+// asked for at once; they take the lock in the order they were asked, and each
+// compares the page's state as it stands when its turn begins against the
+// baseline the save before it left.
 function saveState() {
-    const turn = saveQueue.then(saveStateOnce);
-    // The queue must advance even when a save rejects, or every save after
-    // it queues behind a promise that never settles.
-    saveQueue = turn.catch(() => {});
+    const turn = withLock("autistmask", saveStateOnce);
     // Every failed save is reported, whether or not the caller awaited this
     // one. The returned promise still rejects, so a caller that DOES await
     // keeps its own error handling.

src/shared/transactions.js

@@ -20,6 +20,7 @@ const { toDecimals } = require("./transferAmount");
 // truncation without the approval screens' nonzero floor: the transaction
 // detail view is the authoritative record and already shows exact precision.
 const { truncateAmount: formatTxValue } = require("./amountDisplay");
+const { routerRelease } = require("./uniswap");
 
 // Ethereum addresses are case-insensitive: EIP-55 mixed case is a checksum
 // over the address, not part of its identity.  Every address comparison in
@@ -51,7 +52,6 @@ function parseTx(tx, addrLower, chainId) {
         }
         // Map known DEX methods to "Swap" for cleaner display
         const SWAP_METHODS = new Set([
-            "execute",
             "swap",
             "swapExactTokensForTokens",
             "swapTokensForExactTokens",
@@ -59,9 +59,16 @@ function parseTx(tx, addrLower, chainId) {
             "swapTokensForExactETH",
             "swapExactTokensForETH",
             "swapETHForExactTokens",
-            "multicall",
         ]);
-        const label = SWAP_METHODS.has(method)
+        // Multisigs, smart accounts and many other contracts also have an
+        // `execute` or `multicall` method, so either is a swap only when sent
+        // to a Universal Router on this transaction's network: the same
+        // addresses the approval screen decodes a swap for.
+        const isSwap =
+            SWAP_METHODS.has(method) ||
+            ((method === "execute" || method === "multicall") &&
+                routerRelease(to, chainId) !== null);
+        const label = isSwap
             ? "Swap"
             : method.charAt(0).toUpperCase() + method.slice(1);
         direction = "contract";

src/shared/transferAmount.js

@@ -2,11 +2,11 @@
 // encoded with.
 //
 // A token amount is a decimal string plus a scale, and the two come from
-// different places. The confirmation screen renders the amount, the balance and
-// the symbol from the block explorer's cached metadata (see
-// fetchTokenBalances() in balances.js); the transfer used to be encoded from
-// decimals() read off the contract at signing time, and nothing compared the
-// two. A token whose on-chain scale differs from the cached one — an
+// different places. The confirmation screen renders the amount, the symbol and
+// the balance it reads from the node with the block explorer's cached metadata
+// (see fetchTokenBalances() in balances.js); the transfer used to be encoded
+// from decimals() read off the contract at signing time, and nothing compared
+// the two. A token whose on-chain scale differs from the cached one — an
 // upgradeable or proxy token, a caller-dependent one, a stale or wrong explorer
 // entry — therefore signed an amount that was never displayed, off by a power
 // of ten for every decimal place of disagreement.

tests/accountsChangedOpaqueOrigin.test.js

@@ -0,0 +1,167 @@
+// A page whose origin has no host is never told an address by accountsChanged
+// (https://git.eeqj.de/sneak/AutistMask/issues/564).
+//
+// When the user switches address, the background tells each open tab the new
+// active address if the site at the tab's URL is connected. A page at a
+// connected site's URL can still have another origin: one its server
+// sandboxes with a Content-Security-Policy has the origin "null", and every
+// request it makes is refused. Each test here switches the address in the real
+// background, takes the event it sent to a tab at the site's URL, and hands
+// that event to the real content script in a page of the given origin.
+
+const { networkById } = require("../src/shared/networks");
+const { makeStorageStub } = require("./support/storageStub");
+
+const ADDRESS = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
+const SITE = "https://dapp.example";
+
+const EXT_URL = "chrome-extension://autistmask/";
+const FROM_POPUP = { url: EXT_URL + "src/popup/index.html" };
+
+// One address, with SITE remembered as allowed for it.
+function storedProfile() {
+    const mainnet = networkById("mainnet");
+    return {
+        hasWallet: true,
+        wallets: [
+            {
+                name: "Wallet 1",
+                type: "hd",
+                addresses: [
+                    { address: ADDRESS, balance: "0", tokenBalances: [] },
+                ],
+            },
+        ],
+        activeAddress: ADDRESS,
+        networkId: "mainnet",
+        rpcUrl: mainnet.defaultRpcUrl,
+        blockscoutUrl: mainnet.defaultBlockscoutUrl,
+        allowedSites: { [ADDRESS]: [SITE] },
+        deniedSites: {},
+        trackedTokens: [],
+    };
+}
+
+async function settle() {
+    for (let i = 0; i < 50; i++) await Promise.resolve();
+}
+
+afterEach(() => {
+    delete global.chrome;
+    delete global.window;
+    jest.resetModules();
+});
+
+// The popup tells the background the active address changed, and the one
+// open tab, at SITE's URL, is sent an event. That event is returned.
+async function eventSentToSiteTab() {
+    jest.resetModules();
+    jest.doMock("../src/shared/balances", () => ({
+        getProvider: () => ({}),
+        refreshBalances: jest.fn(async () => {}),
+    }));
+    jest.doMock("../src/shared/phishingDomains", () => ({
+        isPhishingDomain: () => false,
+    }));
+    jest.doMock("../src/shared/alarms", () => ({
+        BALANCE_REFRESH_ALARM: "balance",
+        BALANCE_REFRESH_PERIOD_MINUTES: 1,
+        ensureRecurringAlarms: jest.fn(async () => {}),
+        registerAlarmHandlers: jest.fn(),
+    }));
+
+    let messageListener = null;
+    const sentToTabs = [];
+    global.chrome = {
+        storage: makeStorageStub({ autistmask: storedProfile() }),
+        runtime: {
+            getURL: (path) => EXT_URL + path,
+            onMessage: {
+                addListener: (fn) => {
+                    messageListener = fn;
+                },
+            },
+            onConnect: { addListener: () => {} },
+            getPlatformInfo: (cb) => cb({ os: "linux" }),
+            lastError: null,
+        },
+        windows: {
+            remove: (id, cb) => {
+                if (cb) cb();
+            },
+            onRemoved: { addListener: () => {} },
+        },
+        tabs: {
+            query: (q, cb) => cb([{ id: 1, url: SITE + "/app" }]),
+            sendMessage: (tabId, msg, cb) => {
+                sentToTabs.push(msg);
+                if (cb) cb();
+            },
+        },
+        action: { setPopup: () => {} },
+    };
+
+    require("../src/background/index");
+    messageListener(
+        { type: "AUTISTMASK_ACTIVE_CHANGED" },
+        FROM_POPUP,
+        () => {},
+    );
+    await settle();
+
+    expect(sentToTabs).toHaveLength(1);
+    return sentToTabs[0];
+}
+
+// The content script in a page whose origin is `pageOrigin` is handed `event`
+// from the background. What it posts to the page is returned.
+function postedToPage(event, pageOrigin) {
+    jest.resetModules();
+    let eventListener = null;
+    const posted = [];
+    global.chrome = {
+        runtime: {
+            onMessage: {
+                addListener: (fn) => {
+                    eventListener = fn;
+                },
+            },
+        },
+    };
+    global.window = {
+        origin: pageOrigin,
+        addEventListener: () => {},
+        postMessage: (data) => posted.push(data),
+    };
+
+    require("../src/content/index");
+    eventListener(event);
+
+    return posted;
+}
+
+describe("accountsChanged after an address switch, at a connected site's URL", () => {
+    test("the site's own page is told the active address", async () => {
+        const event = await eventSentToSiteTab();
+
+        expect(postedToPage(event, SITE)).toEqual([
+            {
+                type: "AUTISTMASK_EVENT",
+                eventName: "accountsChanged",
+                data: [ADDRESS],
+            },
+        ]);
+    });
+
+    test("a page whose origin has no host is told no address", async () => {
+        const event = await eventSentToSiteTab();
+
+        expect(postedToPage(event, "null")).toEqual([
+            {
+                type: "AUTISTMASK_EVENT",
+                eventName: "accountsChanged",
+                data: [],
+            },
+        ]);
+    });
+});

tests/addressKey.test.js

@@ -230,7 +230,7 @@ beforeEach(() => {
 
     addWallet.init({
         renderWalletList: () => {},
-        doRefreshAndRender: () => {},
+        startRefresh: () => {},
         pageClosed: new AbortController().signal,
     });
     confirmTx.init({});
@@ -442,11 +442,25 @@ describe("a confirmation screen whose From is not the selected address", () => {
         expect(Transaction.from(signed).from).toBe(derived(1).address);
     });
 
+    // The refusal's sentence is fixed in index.html, in a box of its own that
+    // holds its space from the first paint, so showing it moves nothing.
     test("nothing is sent when the selected wallet does not hold it", async () => {
         expect(await confirmSend(derived(5).address, 0)).toBeUndefined();
-        expect(node("confirm-tx-password-error").textContent).toBe(
-            "The selected wallet does not hold the From address above, " +
-                "so nothing was sent. Please go back and send again.",
+        expect(node("confirm-from-address-error").style.visibility).toBe(
+            "visible",
+        );
+        expect(node("confirm-tx-password-error").textContent).toBe("");
+
+        // Reviewing a send again draws the screen again, which hides it.
+        confirmTx.show({
+            from: derived(0).address,
+            to: RECIPIENT,
+            amount: "0.5",
+            token: "ETH",
+        });
+        await settle();
+        expect(node("confirm-from-address-error").style.visibility).toBe(
+            "hidden",
         );
     });
 });

tests/addressScanCancelled.test.js

@@ -94,7 +94,7 @@ describe.each([
     async function create(pageClosed) {
         addWallet.init({
             renderWalletList: () => {},
-            doRefreshAndRender: () => {},
+            startRefresh: () => {},
             pageClosed,
         });
         element("tab-" + mode).listeners.click();

tests/addressWarnings.test.js

@@ -0,0 +1,39 @@
+// The confirmation screen's warning for a recipient that has never sent a
+// transaction (https://git.eeqj.de/sneak/AutistMask/issues/528).
+//
+// The node's transaction count for an address is the number of transactions
+// it has sent, so an address that only ever receives, such as a savings
+// address or an exchange deposit address, has a count of zero. The warning
+// used to fire on that count alone. It now also needs a zero balance: ETH an
+// address received stays in its balance until it sends a transaction.
+
+"use strict";
+
+const { getFullWarnings } = require("../src/shared/addressWarnings");
+
+global.fetch = jest.fn(async () => {
+    throw new Error("tests must not perform network requests");
+});
+
+const RECIPIENT = "0x" + "b".repeat(40);
+
+// The warning types getFullWarnings() returns for RECIPIENT when the node
+// reports it as a regular address with `txCount` sent transactions and a
+// balance of `balance` wei.
+async function warningTypes(txCount, balance) {
+    const provider = {
+        getCode: async () => "0x",
+        getTransactionCount: async () => txCount,
+        getBalance: async () => balance,
+    };
+    const warnings = await getFullWarnings(RECIPIENT, provider);
+    return warnings.map((w) => w.type);
+}
+
+test("a recipient that has received 0.5 ETH and never sent a transaction gets no warning", async () => {
+    expect(await warningTypes(0, 500000000000000000n)).toEqual([]);
+});
+
+test("a recipient that has never sent a transaction and holds no ETH gets the warning", async () => {
+    expect(await warningTypes(0, 0n)).toEqual(["new-address"]);
+});

tests/approvalDisplayFloor.test.js

@@ -68,7 +68,14 @@ function swapData(amountIn, amountOutMin) {
 }
 
 function swapDetail(amountIn, amountOutMin, label) {
-    const decoded = uniswap.decode(swapData(amountIn, amountOutMin), ROUTER);
+    // Sent by the address the swap pays, so the output is the user's.
+    const decoded = uniswap.decode(
+        swapData(amountIn, amountOutMin),
+        ROUTER,
+        "0x1",
+        {},
+        RECIPIENT,
+    );
     return decoded.details.find((d) => d.label === label);
 }
 

tests/approvalTokenNetwork.test.js

@@ -0,0 +1,270 @@
+// The approval screen for a site's Sepolia token transfer while Ethereum
+// Mainnet is active.
+//
+// The screen named the token, and scaled its amount, from the active network's
+// tracked tokens and balances, so a token the wallet tracks on Sepolia read as
+// an unknown token with its amount in base units, and the screens after it
+// labelled the amount `?` (https://git.eeqj.de/sneak/AutistMask/issues/629).
+// It now uses what the wallet knows of the tokens on the network the
+// transaction is for.
+//
+// Its address links opened the active network's explorer
+// (https://git.eeqj.de/sneak/AutistMask/issues/631). They now open the
+// explorer of the network the transaction is for.
+//
+// Driven through the real approval screen, password and Confirm included,
+// against a minimal DOM stub in the shape tests/swapStatusAmount.test.js uses.
+// The vault is mocked so that no password has to be hashed.
+
+jest.mock("../src/shared/vault", () => ({
+    decryptWithPassword: jest.fn(),
+}));
+
+globalThis.chrome = {
+    storage: { local: { get: async () => ({}), set: async () => {} } },
+};
+
+const { Interface } = require("ethers");
+const { state } = require("../src/shared/state");
+const { NETWORKS } = require("../src/shared/networks");
+const { decryptWithPassword } = require("../src/shared/vault");
+const approval = require("../src/popup/views/approval");
+const txStatus = require("../src/popup/views/txStatus");
+
+// A well-known test phrase, and its first address.
+const PHRASE = "test test test test test test test test test test test junk";
+const FROM = "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266";
+const RECIPIENT = "0x711e691962E5c054b78071C789A0C8CE657377aD";
+// A token the bundled token list does not name.
+const TOKEN = "0x74de5d4FCbf63E00296fd95d33236B9794016631";
+
+// FROM sends 1234.5 of the 6-decimal token to RECIPIENT.
+const TRANSFER_DATA = new Interface([
+    "function transfer(address to, uint256 amount)",
+]).encodeFunctionData("transfer", [RECIPIENT, 1234500000n]);
+
+function makeElement(id) {
+    const classes = new Set();
+    const el = {
+        id,
+        textContent: "",
+        value: "",
+        innerHTML: "",
+        disabled: false,
+        style: {},
+        dataset: {},
+        listeners: {},
+        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: (name, fn) => {
+            el.listeners[name] = el.listeners[name] || [];
+            el.listeners[name].push(fn);
+        },
+        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);
+}
+
+function click(id) {
+    return Promise.all((node(id).listeners.click || []).map((fn) => fn()));
+}
+
+// One line of the decoded details: its label and what is drawn under it.
+function decodedLine(label) {
+    return node("approve-tx-decoded-details")
+        .innerHTML.split('<div class="mb-2">')
+        .find((line) =>
+            line.startsWith(`<div class="text-muted">${label}</div>`),
+        );
+}
+
+// Open the approval screen, with Ethereum Mainnet active and FROM holding
+// `tokenBalances` there, for the site's transaction sending TRANSFER_DATA to
+// the token, on Sepolia unless `chainId` names another chain. Confirm answers
+// the signed transaction with a failure, which leads to the error screen.
+async function showTokenTransfer(
+    tokenBalances = [],
+    chainId = NETWORKS.sepolia.chainId,
+) {
+    globalThis.document = makeDocument();
+    globalThis.window = { location: { search: "" }, close: () => {} };
+    globalThis.chrome.runtime = {
+        connect: () => ({ postMessage: () => {} }),
+        sendMessage: (msg, reply) => {
+            if (!reply) return;
+            if (msg.type !== "AUTISTMASK_GET_APPROVAL") {
+                return reply({
+                    error: "The transaction could not be sent.",
+                    retryable: false,
+                });
+            }
+            reply({
+                type: "tx",
+                origin: "https://dapp.example",
+                isPhishingDomain: false,
+                approvedFrom: FROM,
+                approvedTx: {
+                    type: 2,
+                    from: FROM,
+                    chainId,
+                    nonce: "0x7",
+                    gasLimit: "0x30d40",
+                    maxPriorityFeePerGas: "0x3b9aca00",
+                    maxFeePerGas: "0x77359400",
+                    to: TOKEN,
+                    value: "0x0",
+                    data: TRANSFER_DATA,
+                    accessList: [],
+                },
+            });
+        },
+    };
+    state.networkId = "mainnet";
+    state.activeAddress = FROM;
+    state.wallets = [
+        {
+            type: "hd",
+            name: "Wallet 1",
+            xpub: "xpub-wallet-1",
+            encryptedSecret: "encrypted-secret-1",
+            nextIndex: 1,
+            addresses: [
+                { address: FROM, index: 0, balance: "0", tokenBalances },
+            ],
+        },
+    ];
+    state.currentView = null;
+    txStatus.init({ doRefreshAndRender: () => {} });
+    approval.init({});
+    await approval.show(1);
+}
+
+async function confirm() {
+    decryptWithPassword.mockResolvedValue(PHRASE);
+    node("approve-tx-password").value = "any password";
+    await click("btn-approve-tx");
+}
+
+beforeEach(() => {
+    state.trackedTokens = [];
+    state.networkTrackedTokens = {};
+});
+
+describe("a token tracked on Sepolia only", () => {
+    beforeEach(() => {
+        state.networkTrackedTokens = {
+            sepolia: [{ address: TOKEN, symbol: "TDOL", decimals: 6 }],
+        };
+    });
+
+    test("is named on the Contract line and the decoded Token line, with its amount at its scale", async () => {
+        await showTokenTransfer();
+        expect(node("approve-tx-to").innerHTML).toContain(
+            '<div class="font-bold mb-1">TDOL</div>',
+        );
+        expect(decodedLine("Token")).toContain(
+            '<div class="font-bold">TDOL</div>',
+        );
+        expect(decodedLine("Amount")).toContain(
+            '<div class="font-bold">1234.5000 TDOL</div>',
+        );
+    });
+
+    test("labels the amount on the error screen that follows", async () => {
+        await showTokenTransfer();
+        await confirm();
+        expect(state.currentView).toBe("error-tx");
+        expect(node("error-tx-summary").textContent).toBe("1234.5000 TDOL");
+    });
+});
+
+// The same contract address on mainnet is another token, so what the wallet
+// tracks and holds there names nothing on Sepolia.
+test("a token tracked and held on mainnet only is not named, and its amount is in base units", async () => {
+    state.trackedTokens = [{ address: TOKEN, symbol: "MDOL", decimals: 18 }];
+    await showTokenTransfer([
+        { address: TOKEN, symbol: "MDOL", decimals: 18, balance: "1.0" },
+    ]);
+    expect(node("approve-tx-to").innerHTML).not.toContain("MDOL");
+    expect(decodedLine("Token")).toContain(
+        '<div class="font-bold">Unknown token</div>',
+    );
+    expect(decodedLine("Amount")).toContain(
+        '<div class="font-bold">1234500000 base units (decimals unknown)</div>',
+    );
+});
+
+// The From and Contract lines, and the decoded Token and Recipient lines.
+test("every address links to the Sepolia explorer", async () => {
+    await showTokenTransfer();
+    const sepolia = NETWORKS.sepolia.explorerUrl;
+    expect(node("approve-tx-from").innerHTML).toContain(
+        `href="${sepolia}/address/${FROM}"`,
+    );
+    expect(node("approve-tx-to").innerHTML).toContain(
+        `href="${sepolia}/address/${TOKEN}"`,
+    );
+    expect(decodedLine("Token")).toContain(
+        `href="${sepolia}/address/${TOKEN}"`,
+    );
+    expect(decodedLine("Recipient")).toContain(
+        `href="${sepolia}/address/${RECIPIENT}"`,
+    );
+    for (const id of [
+        "approve-tx-from",
+        "approve-tx-to",
+        "approve-tx-decoded-details",
+    ]) {
+        expect(node(id).innerHTML).not.toContain(NETWORKS.mainnet.explorerUrl);
+    }
+});
+
+// Chain id 1337 names no network here, so it has no explorer to link to.
+test("a transaction on a chain id that names no network is shown with no address links", async () => {
+    await showTokenTransfer([], "0x539");
+    expect(state.currentView).toBe("approve-tx");
+    expect(node("approve-tx-network").textContent).toBe(
+        "Unknown network (chain id 1337)",
+    );
+    expect(node("approve-tx-from").innerHTML).toContain(FROM);
+    for (const id of [
+        "approve-tx-from",
+        "approve-tx-to",
+        "approve-tx-decoded-details",
+    ]) {
+        expect(node(id).innerHTML).not.toContain("href=");
+    }
+});

tests/approvalValueUsd.test.js

@@ -0,0 +1,192 @@
+// The USD value on the approval screen's Value and Network fee lines, for a
+// site's ETH send.
+//
+// It was worked out from the four-decimal figure the line shows, at the price
+// on the active network, so the same value read a few cents different here than
+// on the confirmation screen, which prices the exact amount at the price on the
+// transaction's own network, and a transaction on another network than the
+// active one was priced at the active one's rate, its fee too
+// (https://git.eeqj.de/sneak/AutistMask/issues/614).
+//
+// Driven through the real approval screen, against a minimal DOM stub in the
+// shape tests/approvalTokenNetwork.test.js uses.
+
+globalThis.chrome = {
+    storage: { local: { get: async () => ({}), set: async () => {} } },
+};
+
+const { state } = require("../src/shared/state");
+const { NETWORKS } = require("../src/shared/networks");
+const { prices, clearPrices } = require("../src/shared/prices");
+const approval = require("../src/popup/views/approval");
+
+const FROM = "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266";
+const RECIPIENT = "0x711e691962E5c054b78071C789A0C8CE657377aD";
+
+function makeElement(id) {
+    const classes = new Set();
+    const el = {
+        id,
+        textContent: "",
+        value: "",
+        innerHTML: "",
+        disabled: false,
+        style: {},
+        dataset: {},
+        listeners: {},
+        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: (name, fn) => {
+            el.listeners[name] = el.listeners[name] || [];
+            el.listeners[name].push(fn);
+        },
+        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);
+}
+
+// Open the approval screen, with the network `networkId` active, for the
+// site's transaction sending 1.23414 ETH to RECIPIENT on the chain `chainId`.
+async function showEthSend(chainId, networkId) {
+    globalThis.document = makeDocument();
+    globalThis.window = { location: { search: "" }, close: () => {} };
+    globalThis.chrome.runtime = {
+        connect: () => ({ postMessage: () => {} }),
+        sendMessage: (msg, reply) => {
+            if (!reply) return;
+            reply({
+                type: "tx",
+                origin: "https://dapp.example",
+                isPhishingDomain: false,
+                approvedFrom: FROM,
+                approvedTx: {
+                    type: 2,
+                    from: FROM,
+                    chainId,
+                    nonce: "0x7",
+                    gasLimit: "0x5208",
+                    maxPriorityFeePerGas: "0x3b9aca00",
+                    maxFeePerGas: "0x77359400",
+                    to: RECIPIENT,
+                    value: "1234140000000000000",
+                    data: "0x",
+                    accessList: [],
+                },
+            });
+        },
+    };
+    state.networkId = networkId;
+    state.activeAddress = FROM;
+    state.wallets = [
+        {
+            type: "hd",
+            name: "Wallet 1",
+            xpub: "xpub-wallet-1",
+            encryptedSecret: "encrypted-secret-1",
+            nextIndex: 1,
+            addresses: [{ address: FROM, index: 0, balance: "0" }],
+        },
+    ];
+    state.trackedTokens = [];
+    state.networkTrackedTokens = {};
+    state.currentView = null;
+    approval.init({});
+    await approval.show(1);
+}
+
+beforeEach(() => {
+    prices.ETH = 2000;
+});
+
+afterEach(() => {
+    clearPrices();
+});
+
+// 1.23414 ETH reads 1.2341 ETH. At $2,000 the exact value is $2,468.28, the
+// figure the confirmation screen shows for it; the shown figure would be
+// $2,468.20.
+test.each([
+    [
+        "a mainnet transaction is priced from its exact value",
+        NETWORKS.mainnet.chainId,
+        "mainnet",
+        "1.2341 ETH ($2,468.28)",
+    ],
+    [
+        "a mainnet transaction shown with Sepolia active is priced at the mainnet price",
+        NETWORKS.mainnet.chainId,
+        "sepolia",
+        "1.2341 ETH ($2,468.28)",
+    ],
+    [
+        "a Sepolia transaction shown with mainnet active has no USD value",
+        NETWORKS.sepolia.chainId,
+        "mainnet",
+        "1.2341 SepoliaETH",
+    ],
+    // Chain id 1337 names no network here, so nothing knows its price.
+    [
+        "a transaction on a chain id that names no network has no USD value",
+        "0x539",
+        "mainnet",
+        "1.2341 ETH",
+    ],
+])("%s", async (_label, chainId, networkId, expected) => {
+    await showEthSend(chainId, networkId);
+    expect(state.currentView).toBe("approve-tx");
+    expect(node("approve-tx-value").textContent).toBe(expected);
+});
+
+// The Network fee line is priced on the transaction's network too. 21000 gas at
+// up to 2 gwei is 0.000042 ETH, $0.08 at $2,000.
+test.each([
+    [
+        "the fee of a mainnet transaction shown with Sepolia active is priced at the mainnet price",
+        NETWORKS.mainnet.chainId,
+        "sepolia",
+        "0.00004 ETH ($0.08)",
+    ],
+    [
+        "the fee of a Sepolia transaction shown with mainnet active has no USD value",
+        NETWORKS.sepolia.chainId,
+        "mainnet",
+        "0.00004 SepoliaETH",
+    ],
+])("%s", async (_label, chainId, networkId, expected) => {
+    await showEthSend(chainId, networkId);
+    expect(state.currentView).toBe("approve-tx");
+    expect(node("approve-tx-fee").textContent).toBe(expected);
+});

tests/backNavigation.test.js

@@ -154,7 +154,14 @@ describe("Back onto a view the reopened popup never rendered", () => {
 
     test("Back onto the transaction detail renders it", () => {
         reopenedOn("settings", ["main", "transaction"], {
-            viewData: { tx: { hash: "0xdead", from: ADDRESS, to: ADDRESS } },
+            viewData: {
+                tx: {
+                    hash: "0xdead",
+                    from: ADDRESS,
+                    to: ADDRESS,
+                    chainId: "0x1",
+                },
+            },
         });
         goBack();
         expect(calls).toEqual(["transactionDetail"]);

tests/coldWorkerChainSwitch.test.js

@@ -204,17 +204,21 @@ describe("a chain switch on a worker that never loaded state", () => {
         expect(after.rpcUrl).toBe(SEPOLIA.defaultRpcUrl);
 
         // And it took nothing else with it. Without the load these come back
-        // as [], {}, [] and "system" from DEFAULT_STATE — every wallet in the
+        // as [], {}, {} and "system" from DEFAULT_STATE — every wallet in the
         // extension gone, encrypted secrets included.
         expect(after.wallets).toEqual(walletFixture());
         expect(after.hasWallet).toBe(true);
         expect(after.activeAddress).toBe(ADDRESS);
         expect(after.allowedSites).toEqual({ [ADDRESS]: [CONNECTED_ORIGIN] });
-        expect(after.trackedTokens).toEqual([
-            { address: TOKEN, symbol: "DAI", decimals: 18 },
-        ]);
+        expect(after.networkTrackedTokens).toEqual({
+            mainnet: [{ address: TOKEN, symbol: "DAI", decimals: 18 }],
+        });
         expect(after.theme).toBe("dark");
 
+        // The mainnet token is tracked on mainnet only: Sepolia starts with
+        // none of its own.
+        expect(after.trackedTokens).toEqual([]);
+
         // The user's mainnet endpoint is remembered rather than replaced by
         // the public default, so switching back returns it.
         expect(after.networkEndpoints.mainnet).toEqual({
@@ -226,6 +230,9 @@ describe("a chain switch on a worker that never loaded state", () => {
         expect(bg.persisted().rpcUrl).toBe(CUSTOM_RPC);
         expect(bg.persisted().blockscoutUrl).toBe(CUSTOM_BLOCKSCOUT);
         expect(bg.persisted().wallets).toEqual(walletFixture());
+        expect(bg.persisted().trackedTokens).toEqual([
+            { address: TOKEN, symbol: "DAI", decimals: 18 },
+        ]);
     });
 
     test("compares the requested chain against the stored one, not the default", async () => {

tests/confirmTxAmount.test.js

@@ -0,0 +1,415 @@
+// The amount of the wallet's own send on the confirmation, wait, success and
+// error screens (https://git.eeqj.de/sneak/AutistMask/issues/522).
+//
+// These screens printed the text from Send's amount field as it was typed or
+// filled in: `0.5 ETH`, or `1.234147890123456789 ETH` after Max, where the
+// approval screen shows a site's send as `0.5000 ETH`. They now show it to four
+// decimal places with the nonzero floor, as the approval screen does, and the
+// transaction is still signed for the exact amount.
+//
+// Driven through the real Send screen, confirmation screen, Sign & Send and
+// wait screen, with only the node, the explorer and the DOM stubbed.
+
+"use strict";
+
+// What the stub node answers, and the signed transactions it was handed. The
+// token's own decimals() answers 6, as the explorer does.
+const mockNode = {
+    balanceWei: 0n,
+    tokenUnits: 0n,
+    tokenDecimals: 6n,
+    broadcast: [],
+    broadcastError: null,
+    receipt: null,
+};
+
+// The token rows the stub explorer reports for the address.
+const mockExplorer = { items: [] };
+
+jest.mock("ethers", () => {
+    const actual = jest.requireActual("ethers");
+    // The selector of decimals(); every other contract call is balanceOf().
+    const DECIMALS = "0x313ce567";
+    class StubProvider {
+        async getBalance() {
+            return mockNode.balanceWei;
+        }
+        async call(tx) {
+            return actual.AbiCoder.defaultAbiCoder().encode(
+                ["uint256"],
+                [
+                    tx.data.startsWith(DECIMALS)
+                        ? mockNode.tokenDecimals
+                        : mockNode.tokenUnits,
+                ],
+            );
+        }
+        async lookupAddress() {
+            return null;
+        }
+        // 20 gwei reserved per gas.
+        async getFeeData() {
+            return {
+                maxFeePerGas: 20000000000n,
+                maxPriorityFeePerGas: 1000000000n,
+                gasPrice: 10000000000n,
+            };
+        }
+        async estimateGas() {
+            return 21000n;
+        }
+        async getCode() {
+            return "0x";
+        }
+        async getTransactionCount() {
+            return 1;
+        }
+        async getNetwork() {
+            return { chainId: 1n };
+        }
+        async broadcastTransaction(signed) {
+            if (mockNode.broadcastError) throw mockNode.broadcastError;
+            mockNode.broadcast.push(signed);
+            return { hash: "0x" + "ab".repeat(32) };
+        }
+        async getTransactionReceipt() {
+            return mockNode.receipt;
+        }
+    }
+    return {
+        ...actual,
+        JsonRpcProvider: StubProvider,
+        Network: { from: () => ({}) },
+    };
+});
+
+jest.mock("../src/shared/log", () => ({
+    log: {
+        debugf: () => {},
+        infof: () => {},
+        warnf: () => {},
+        errorf: () => {},
+    },
+    // The explorer's token list, which refreshBalances() also fetches.
+    debugFetch: jest.fn(async () => ({
+        ok: true,
+        status: 200,
+        json: async () => mockExplorer.items,
+    })),
+    urlOrigin: () => "",
+    setRuntimeDebug: () => {},
+    isDebug: () => false,
+}));
+
+// The confirmation screen's Etherscan label lookup is the only fetch() these
+// screens make; it fails, as it does offline.
+global.fetch = jest.fn(() => {
+    throw new Error("tests must not perform network requests");
+});
+
+const { makeStorageStub } = require("./support/storageStub");
+global.chrome = { storage: makeStorageStub(), runtime: { sendMessage() {} } };
+
+// A stub DOM: every id resolves to a recording element.
+const elements = new Map();
+
+function makeEl(id) {
+    const handlers = new Map();
+    return {
+        id,
+        textContent: "",
+        innerHTML: "",
+        value: "",
+        disabled: false,
+        style: {},
+        dataset: {},
+        classList: {
+            add() {},
+            remove() {},
+            toggle() {},
+            contains: () => false,
+        },
+        handlers,
+        children: [],
+        addEventListener(name, fn) {
+            handlers.set(name, fn);
+        },
+        appendChild(child) {
+            this.children.push(child);
+            return child;
+        },
+        querySelectorAll: () => [],
+        querySelector: () => null,
+        remove() {},
+        focus() {},
+        // The success screen hides whole sections through .parentElement.
+        get parentElement() {
+            return global.document.getElementById(id + "-parent");
+        },
+    };
+}
+
+global.document = {
+    getElementById(id) {
+        if (!elements.has(id)) elements.set(id, makeEl(id));
+        return elements.get(id);
+    },
+    createElement: (tag) => makeEl(tag),
+    body: { prepend() {}, appendChild() {} },
+    addEventListener() {},
+};
+global.navigator.clipboard = { writeText() {} };
+
+const {
+    Interface,
+    Transaction,
+    Wallet,
+    getAddress,
+    parseEther,
+} = require("ethers");
+const { refreshBalances } = require("../src/shared/balances");
+const { encryptWithPassword } = require("../src/shared/vault");
+const { state } = require("../src/shared/state");
+const { clearPrices } = require("../src/shared/prices");
+const send = require("../src/popup/views/send");
+const confirmTx = require("../src/popup/views/confirmTx");
+const txStatus = require("../src/popup/views/txStatus");
+
+const PRIVATE_KEY = "0x" + "11".repeat(32);
+const HOLDER = new Wallet(PRIVATE_KEY).address;
+const RECIPIENT = "0xC0FfEE0000000000000000000000000000c0fFEe";
+const PASSWORD = "correct horse battery staple";
+
+const GWEI = 1000000000n;
+// 1.234567890123456789 ETH.
+const BALANCE_WEI = 1234567890123456789n;
+
+// A token the bundled list does not know, with enough holders to be listed,
+// at 6 decimal places.
+const TOKEN = "0x" + "d".repeat(40);
+
+const transferIface = new Interface([
+    "function transfer(address to, uint256 amount)",
+]);
+
+let encryptedSecret;
+
+// The confirmation screen Review leads to, once shown.
+let confirmed = null;
+
+function el(id) {
+    return global.document.getElementById(id);
+}
+
+function text(id) {
+    return el(id).textContent;
+}
+
+// show() reads the balance and then estimates the fee without awaiting
+// either; this lets both settle.
+async function settle() {
+    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+}
+
+// The address holds BALANCE_WEI and, when `tokenUnits` is given, that many
+// base units of TOKEN, fetched and stored where the popup stores them. Send
+// is then open for `token` ("ETH" or TOKEN) with the recipient entered.
+async function openSend(token, tokenUnits = null) {
+    mockNode.balanceWei = BALANCE_WEI;
+    mockNode.tokenUnits = tokenUnits ?? 0n;
+    mockExplorer.items =
+        tokenUnits === null
+            ? []
+            : [
+                  {
+                      value: String(tokenUnits),
+                      token: {
+                          type: "ERC-20",
+                          address_hash: TOKEN,
+                          symbol: "TOK",
+                          name: "Token",
+                          decimals: "6",
+                          holders_count: "50000",
+                      },
+                  },
+              ];
+    state.wallets = [
+        {
+            type: "key",
+            name: "Wallet 1",
+            encryptedSecret,
+            addresses: [{ address: HOLDER }],
+        },
+    ];
+    state.selectedWallet = 0;
+    state.selectedAddress = 0;
+    await refreshBalances(
+        state.wallets,
+        "https://rpc.example.invalid",
+        "https://blockscout.example/api/v2",
+        state.trackedTokens,
+        "mainnet",
+    );
+    send.init({
+        showConfirmTx: (info) => (confirmed = info),
+        pageClosed: new AbortController().signal,
+    });
+    confirmTx.init({});
+    send.resetSendValidation();
+    state.currentView = "send";
+    state.selectedToken = token;
+    el("send-to").value = RECIPIENT;
+    el("send-amount").value = "";
+}
+
+// Press Review and show the confirmation screen with its fee estimate settled.
+async function review() {
+    await el("btn-send-review").handlers.get("click")();
+    confirmTx.show(confirmed);
+    await settle();
+}
+
+async function signAndSend() {
+    el("confirm-tx-password").value = PASSWORD;
+    await el("btn-confirm-send").handlers.get("click")();
+}
+
+// The one transaction the stub node was handed.
+function broadcastTx() {
+    expect(mockNode.broadcast).toHaveLength(1);
+    return Transaction.from(mockNode.broadcast[0]);
+}
+
+beforeAll(async () => {
+    encryptedSecret = await encryptWithPassword(PRIVATE_KEY, PASSWORD);
+});
+
+beforeEach(() => {
+    elements.clear();
+    clearPrices();
+    confirmed = null;
+    state.selectedToken = null;
+    state.trackedTokens = [];
+    state.fraudContracts = [];
+    state.currentView = null;
+    mockNode.broadcast = [];
+    mockNode.broadcastError = null;
+    mockNode.receipt = null;
+    txStatus.init({
+        doRefreshAndRender() {},
+        pageClosed: new AbortController().signal,
+    });
+});
+
+afterEach(() => {
+    txStatus.endWait();
+});
+
+describe("the wallet's own send shows its amount to four decimal places", () => {
+    test("for a short amount", async () => {
+        await openSend("ETH");
+        el("send-amount").value = "0.5";
+        await review();
+        expect(text("confirm-amount")).toBe("0.5000 ETH");
+
+        await signAndSend();
+        expect(text("wait-tx-summary")).toBe("0.5000 ETH");
+        expect(broadcastTx().value).toBe(parseEther("0.5"));
+    });
+
+    // Send accepts both. The approval screen writes the same value `0.5000`.
+    test.each([".5", "00.5"])("for an amount typed as %s", async (typed) => {
+        await openSend("ETH");
+        el("send-amount").value = typed;
+        await review();
+        expect(text("confirm-amount")).toBe("0.5000 ETH");
+
+        await signAndSend();
+        expect(text("wait-tx-summary")).toBe("0.5000 ETH");
+        expect(broadcastTx().value).toBe(parseEther("0.5"));
+    });
+
+    test("for a token amount typed as .5", async () => {
+        // 100 TOK.
+        await openSend(TOKEN, 100000000n);
+        el("send-amount").value = ".5";
+        await review();
+        expect(text("confirm-amount")).toBe("0.5000 TOK");
+
+        await signAndSend();
+        expect(text("wait-tx-summary")).toBe("0.5000 TOK");
+        const [, amount] = transferIface.decodeFunctionData(
+            "transfer",
+            broadcastTx().data,
+        );
+        expect(amount).toBe(500000n);
+    });
+
+    test("for a Max amount with many decimals", async () => {
+        await openSend("ETH");
+        await el("btn-send-max").handlers.get("click")();
+        // The balance minus 21000 gas at 20 gwei.
+        expect(el("send-amount").value).toBe("1.234147890123456789");
+        await review();
+        expect(text("confirm-amount")).toBe("1.2341 ETH");
+
+        await signAndSend();
+        expect(text("wait-tx-summary")).toBe("1.2341 ETH");
+        expect(broadcastTx().value).toBe(BALANCE_WEI - 21000n * 20n * GWEI);
+    });
+
+    // Cut to four decimals it would read 0.0000, so it is shown to its first
+    // significant digit instead, and signed in full.
+    test("for a tiny nonzero amount", async () => {
+        await openSend("ETH");
+        el("send-amount").value = "0.000012345";
+        await review();
+        expect(text("confirm-amount")).toBe("0.00001 ETH");
+
+        await signAndSend();
+        expect(text("wait-tx-summary")).toBe("0.00001 ETH");
+        expect(broadcastTx().value).toBe(parseEther("0.000012345"));
+    });
+
+    test("for a token amount", async () => {
+        // 100 TOK.
+        await openSend(TOKEN, 100000000n);
+        el("send-amount").value = "12.345678";
+        await review();
+        expect(text("confirm-amount")).toBe("12.3456 TOK");
+
+        await signAndSend();
+        expect(text("wait-tx-summary")).toBe("12.3456 TOK");
+        const tx = broadcastTx();
+        expect(tx.to).toBe(getAddress(TOKEN));
+        const [to, amount] = transferIface.decodeFunctionData(
+            "transfer",
+            tx.data,
+        );
+        expect(to).toBe(RECIPIENT);
+        expect(amount).toBe(12345678n);
+    });
+
+    test("on the success screen", async () => {
+        await openSend("ETH");
+        el("send-amount").value = "0.5";
+        await review();
+        await signAndSend();
+        // A popup opened later resumes the wait, and the receipt is there.
+        mockNode.receipt = { blockNumber: 21000000 };
+        txStatus.restoreWait();
+        await settle();
+        expect(state.currentView).toBe("success-tx");
+        expect(text("success-tx-summary")).toBe("0.5000 ETH");
+    });
+
+    test("on the error screen", async () => {
+        await openSend("ETH");
+        el("send-amount").value = "0.5";
+        await review();
+        mockNode.broadcastError = new Error("the node refused it");
+        await signAndSend();
+        expect(state.currentView).toBe("error-tx");
+        expect(text("error-tx-summary")).toBe("0.5000 ETH");
+    });
+});

tests/confirmTxFeeBound.test.js

@@ -11,20 +11,115 @@
 //
 // The check is driven here with a fake connected signer rather than a real
 // one: populateTransaction() returns the fees the node would have produced,
-// and sendTransaction() records whether the send actually happened. The real
-// DOM path around it — reading the fee error into the reserved errors box — is
-// covered by the Chrome e2e suite.
+// and sendTransaction() records whether the send actually happened.
+//
+// The last test drives the real confirmation screen instead, with only the
+// node and the DOM stubbed: a gas limit over its own bound at an ordinary fee
+// is refused in the same box as a fee over the bound
+// (https://git.eeqj.de/sneak/AutistMask/issues/583). That the box moves
+// nothing on the screen is checked by the Chrome e2e suite.
 
-globalThis.chrome = {
-    storage: { local: { get: async () => ({}), set: async () => {} } },
+// What the stub node quotes for that test: a gas limit of 150,000,000 at a
+// maximum fee of 2 gwei per gas, 0.3 ETH in all. And the signed transactions
+// it was handed.
+const mockNode = {
+    gasLimit: 150000000n,
+    maxFeePerGas: 2000000000n,
+    broadcast: [],
 };
 
+jest.mock("ethers", () => {
+    const actual = jest.requireActual("ethers");
+    class StubProvider {
+        constructor(url, network) {
+            this.network = network;
+        }
+        async getNetwork() {
+            return this.network;
+        }
+        async getBalance() {
+            return actual.parseEther("5");
+        }
+        async getCode() {
+            return "0x";
+        }
+        async getTransactionCount() {
+            return 1;
+        }
+        async getFeeData() {
+            return {
+                maxFeePerGas: mockNode.maxFeePerGas,
+                maxPriorityFeePerGas: 1000000000n,
+                gasPrice: 1000000000n,
+            };
+        }
+        async estimateGas() {
+            return mockNode.gasLimit;
+        }
+        async broadcastTransaction(signed) {
+            mockNode.broadcast.push(signed);
+            return { hash: "0x" + "ab".repeat(32) };
+        }
+    }
+    return { ...actual, JsonRpcProvider: StubProvider };
+});
+
+// The screens a send that was not refused goes on to.
+jest.mock("../src/popup/views/txStatus", () => ({
+    showWait: jest.fn(),
+    showError: jest.fn(),
+}));
+
+const { makeStorageStub } = require("./support/storageStub");
+global.chrome = { storage: makeStorageStub(), runtime: { sendMessage() {} } };
+
 global.fetch = jest.fn(() => {
     throw new Error("tests must not perform network requests");
 });
 
-const { populateVerifyAndSend } = require("../src/popup/views/confirmTx");
+// A stub DOM: every id resolves to a recording element.
+const elements = new Map();
+
+function makeEl(id) {
+    const handlers = new Map();
+    return {
+        id,
+        textContent: "",
+        innerHTML: "",
+        value: "",
+        disabled: false,
+        style: {},
+        dataset: {},
+        classList: {
+            add() {},
+            remove() {},
+            toggle() {},
+            contains: () => false,
+        },
+        handlers,
+        addEventListener(name, fn) {
+            handlers.set(name, fn);
+        },
+        querySelectorAll: () => [],
+        remove() {},
+    };
+}
+
+global.document = {
+    getElementById(id) {
+        if (!elements.has(id)) elements.set(id, makeEl(id));
+        return elements.get(id);
+    },
+};
+
+const { Wallet } = require("ethers");
+const { encryptWithPassword } = require("../src/shared/vault");
+const { state, loadState } = require("../src/shared/state");
+const txStatus = require("../src/popup/views/txStatus");
+const confirmTx = require("../src/popup/views/confirmTx");
+const { populateVerifyAndSend } = confirmTx;
 const {
+    MAX_GAS_LIMIT,
     MAX_FEE_PER_GAS,
     MAX_TOTAL_FEE,
 } = require("../src/shared/approvalVerify");
@@ -98,3 +193,69 @@ describe("populateVerifyAndSend enforces the combined fee bound", () => {
         expect(signer.sent[0].gasLimit).toBe(under.gasLimit);
     });
 });
+
+describe("Sign & Send on the confirmation screen", () => {
+    const PRIVATE_KEY = "0x" + "11".repeat(32);
+    const PASSWORD = "correct horse battery staple";
+    let encryptedSecret;
+
+    beforeAll(async () => {
+        await loadState();
+        encryptedSecret = await encryptWithPassword(PRIVATE_KEY, PASSWORD);
+    });
+
+    function el(id) {
+        return global.document.getElementById(id);
+    }
+
+    function shown(id) {
+        return el(id).style.visibility === "visible";
+    }
+
+    // show() reads the balance and estimates the fee without awaiting
+    // either; this lets both finish.
+    async function settle() {
+        for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+    }
+
+    test("refuses a gas limit over its bound at an ordinary fee in the box for a refused gas limit or fee, and sends nothing", async () => {
+        expect(mockNode.gasLimit).toBeGreaterThan(MAX_GAS_LIMIT);
+        expect(mockNode.gasLimit * mockNode.maxFeePerGas).toBeLessThan(
+            MAX_TOTAL_FEE,
+        );
+
+        const from = new Wallet(PRIVATE_KEY).address;
+        state.wallets = [
+            {
+                type: "key",
+                name: "Wallet 1",
+                encryptedSecret,
+                addresses: [{ address: from }],
+            },
+        ];
+        state.selectedWallet = 0;
+        state.selectedAddress = 0;
+        confirmTx.init({});
+        confirmTx.show({
+            from,
+            to: RECIPIENT,
+            ensName: null,
+            amount: "1",
+            token: "ETH",
+            tokenSymbol: null,
+            tokenDecimals: null,
+            max: false,
+        });
+        await settle();
+        expect(el("btn-confirm-send").disabled).toBe(false);
+        expect(shown("confirm-fee-bound-error")).toBe(false);
+
+        el("confirm-tx-password").value = PASSWORD;
+        await el("btn-confirm-send").handlers.get("click")();
+
+        expect(shown("confirm-fee-bound-error")).toBe(true);
+        expect(mockNode.broadcast).toEqual([]);
+        expect(txStatus.showWait).not.toHaveBeenCalled();
+        expect(txStatus.showError).not.toHaveBeenCalled();
+    });
+});

tests/confirmTxLateResult.test.js

@@ -0,0 +1,221 @@
+// A late answer for a confirmation screen the user has left changes nothing on
+// the screen shown since (https://git.eeqj.de/sneak/AutistMask/issues/575).
+//
+// The confirmation screen asks the node and the explorer about its transaction
+// without waiting for the answers: the recipient checks, which can show three
+// warning boxes, the balance read and the fee estimate. Back, a new recipient
+// and Review again show the screen for another transaction while those
+// questions may still be open. The recipient checks showed their boxes
+// whenever they answered, so a box about the first recipient could appear on
+// the second recipient's screen.
+//
+// Driven through the real confirmation screen, with only the node, the
+// explorer and the DOM stubbed. Each test holds back the first screen's answer
+// to one question, and gives it once the screen it tests is shown.
+
+"use strict";
+
+// The From address of every transaction here. The jest.mock() factory below
+// may only name outside variables whose names start with "mock".
+const mockFrom = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
+
+jest.mock("ethers", () => {
+    const actual = jest.requireActual("ethers");
+    // Every answer is a mock, so a test can hold one back. Every address has
+    // sent one transaction and has no code, and only the From address holds
+    // anything: 5 ETH.
+    class StubProvider {}
+    Object.assign(StubProvider.prototype, {
+        getBalance: jest.fn(async (address) =>
+            address === mockFrom ? actual.parseEther("5") : 0n,
+        ),
+        getCode: jest.fn(async () => "0x"),
+        getTransactionCount: jest.fn(async () => 1),
+        // 10 gwei expected, 20 gwei reserved per gas.
+        getFeeData: jest.fn(async () => ({
+            maxFeePerGas: 20000000000n,
+            maxPriorityFeePerGas: 1000000000n,
+            gasPrice: 10000000000n,
+        })),
+        estimateGas: jest.fn(async () => 21000n),
+    });
+    return { ...actual, JsonRpcProvider: StubProvider };
+});
+
+// An explorer address page whose title is `title`.
+function explorerPage(title) {
+    return { ok: true, text: async () => "<title>" + title + "</title>" };
+}
+
+// The explorer labels no address.
+global.fetch = jest.fn(async () => explorerPage("Etherscan"));
+
+const { makeStorageStub } = require("./support/storageStub");
+global.chrome = { storage: makeStorageStub(), runtime: { sendMessage() {} } };
+
+// A stub DOM: every id resolves to a recording element.
+const elements = new Map();
+
+function makeEl(id) {
+    return {
+        id,
+        textContent: "",
+        innerHTML: "",
+        value: "",
+        disabled: false,
+        style: {},
+        dataset: {},
+        classList: {
+            add() {},
+            remove() {},
+            toggle() {},
+            contains: () => false,
+        },
+        addEventListener() {},
+        querySelectorAll: () => [],
+        remove() {},
+    };
+}
+
+global.document = {
+    getElementById(id) {
+        if (!elements.has(id)) elements.set(id, makeEl(id));
+        return elements.get(id);
+    },
+};
+
+const { JsonRpcProvider, parseEther } = require("ethers");
+const { loadState } = require("../src/shared/state");
+const confirmTx = require("../src/popup/views/confirmTx");
+
+const node = JsonRpcProvider.prototype;
+const FIRST = "0xC0FfEE0000000000000000000000000000c0fFEe";
+const SECOND = "0xE2E0000000000000000000000000000000000E2e";
+
+function el(id) {
+    return global.document.getElementById(id);
+}
+
+function shown(id) {
+    return el(id).style.visibility === "visible";
+}
+
+// Show the confirmation screen for 1 ETH to `to` on mainnet, as Review on the
+// Send screen does.
+function review(to) {
+    confirmTx.show({
+        from: mockFrom,
+        to,
+        ensName: null,
+        amount: "1",
+        token: "ETH",
+        tokenSymbol: null,
+        tokenDecimals: null,
+        max: false,
+    });
+}
+
+// show() does not wait for its questions; this lets every answer not held
+// back arrive.
+async function settle() {
+    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+}
+
+// Hold back the next answer `question` gives. Returns the function that gives
+// it.
+function holdNextAnswer(question) {
+    let give;
+    question.mockImplementationOnce(() => new Promise((r) => (give = r)));
+    return (answer) => give(answer);
+}
+
+beforeAll(async () => {
+    await loadState();
+});
+
+beforeEach(() => {
+    elements.clear();
+});
+
+// The three boxes the recipient checks show, each with the question whose
+// answer shows it for FIRST, and that answer. FIRST holds no ETH, so the
+// answer that it has sent no transaction is what shows the box saying so.
+describe.each([
+    {
+        box: "confirm-contract-warning",
+        question: node.getCode,
+        answer: "0x6080604052",
+    },
+    {
+        box: "confirm-recipient-warning",
+        question: node.getTransactionCount,
+        answer: 0,
+    },
+    {
+        box: "confirm-etherscan-warning",
+        question: global.fetch,
+        answer: explorerPage(
+            "Fake_Phishing1 | Address: " + FIRST + " | Etherscan",
+        ),
+    },
+])("the $box box", ({ box, question, answer }) => {
+    test("is shown when the answer about the recipient arrives while its screen is shown", async () => {
+        const give = holdNextAnswer(question);
+        review(FIRST);
+        await settle();
+        expect(shown(box)).toBe(false);
+
+        give(answer);
+        await settle();
+        expect(shown(box)).toBe(true);
+    });
+
+    test("is not shown on the next recipient's screen when the answer about the first arrives after that screen is shown", async () => {
+        const give = holdNextAnswer(question);
+        review(FIRST);
+        await settle();
+        review(SECOND);
+        await settle();
+        expect(shown(box)).toBe(false);
+
+        give(answer);
+        await settle();
+        expect(shown(box)).toBe(false);
+    });
+});
+
+test("a balance read answered after the next screen is shown leaves that screen's balance and balance check as they are", async () => {
+    const give = holdNextAnswer(node.getBalance);
+    review(FIRST);
+    await settle();
+    review(SECOND);
+    await settle();
+    expect(el("confirm-balance").textContent).toBe("5.0000 ETH");
+
+    give(parseEther("0.5"));
+    await settle();
+    expect(el("confirm-balance").textContent).toBe("5.0000 ETH");
+    expect(shown("confirm-balance-error")).toBe(false);
+    expect(el("btn-confirm-send").disabled).toBe(false);
+});
+
+test("a fee estimate answered after the next screen is shown leaves that screen's fee as it is", async () => {
+    const give = holdNextAnswer(node.getFeeData);
+    review(FIRST);
+    await settle();
+    review(SECOND);
+    await settle();
+    expect(el("confirm-fee-amount").textContent).toBe("~0.0002 ETH");
+
+    // 100 times the fee the second screen was quoted.
+    give({
+        maxFeePerGas: 2000000000000n,
+        maxPriorityFeePerGas: 100000000000n,
+        gasPrice: 1000000000000n,
+    });
+    await settle();
+    expect(el("confirm-fee-amount").textContent).toBe("~0.0002 ETH");
+    expect(el("confirm-fee-reserve").textContent).toBe(
+        "up to 0.0004 ETH reserved",
+    );
+});

tests/confirmTxNetworkSwitch.test.js

@@ -7,29 +7,39 @@
 // reviewed on Sepolia went out as 1 ETH on mainnet once mainnet was chosen in
 // Settings in between.
 //
-// Its balance line and balance check are that network's too
-// (https://git.eeqj.de/sneak/AutistMask/issues/558). The popup can reopen onto
-// a confirmation screen saved before the network was switched in another
-// popup, and the screen, drawn again for the new network, showed and checked
-// the balance Send had read on the old one. The balance read and the fee
-// estimate after it stay on that network when it is switched while they run.
+// The same holds when the popup was closed after the switch and reopened, and
+// Back drew the screen again from the transaction it saved
+// (https://git.eeqj.de/sneak/AutistMask/issues/586): the screen was drawn for
+// the new network, and Sign & Send sent the reviewed transfer there. Drawn
+// again, the screen describes the transaction entirely on the network it was
+// reviewed for, because choosing that network again in Settings and pressing
+// Back only unhides it, and Sign & Send then sends from it.
+//
+// Its balance line and balance check are that network's balance, read from
+// that network's node each time the screen is drawn
+// (https://git.eeqj.de/sneak/AutistMask/issues/558), not the balance Send
+// handed over. The fee estimate after the read stays on that network when
+// the network is switched while the read runs.
 //
 // Driven through the real confirmation screen, signer and chain switch, with
-// only the node and the DOM stubbed. The stub node is on the network its
-// provider was built for, so a broadcast records the network it went to, and
-// a balance read answers with that network's balance.
+// only the node, fetch and the DOM stubbed. The stub node is on the network
+// its provider was built for, so a broadcast records the network it went to,
+// and a balance read answers with that network's balance.
 
 "use strict";
 
-// The balances the stub node reports on each network, by network name: ETH
-// in wei and the token in its base units. The networks whose node was asked
-// for the fee, in order. And the signed transactions it was handed, with its
-// network's chain id.
+// The questions the stub node was asked for the balance, the fee and the
+// recipient checks, by method, network name and RPC URL, in order. The
+// balances it reports on each network, by network name: ETH in wei and the
+// token in its base units. The signed transactions it was handed, with its
+// network's chain id and RPC URL. And whether it quotes fees as a network
+// with no type-2 pricing does.
 const mockNode = {
+    asked: [],
     balanceWei: {},
     tokenUnits: {},
-    feeAskedOn: [],
     broadcast: [],
+    legacyFees: false,
 };
 
 jest.mock("ethers", () => {
@@ -38,12 +48,21 @@ jest.mock("ethers", () => {
     const BALANCE_OF = "0x70a08231";
     class StubProvider {
         constructor(url, network) {
+            this.url = url;
             this.network = network;
         }
+        record(method) {
+            mockNode.asked.push({
+                method,
+                network: this.network.name,
+                url: this.url,
+            });
+        }
         async getNetwork() {
             return this.network;
         }
         async getBalance() {
+            this.record("getBalance");
             return mockNode.balanceWei[this.network.name];
         }
         // balanceOf() is the one contract call the screen makes before Sign
@@ -52,13 +71,21 @@ jest.mock("ethers", () => {
             if (!tx.data.startsWith(BALANCE_OF)) {
                 throw new Error("the stub node answers only balanceOf()");
             }
+            this.record("balanceOf");
             return actual.AbiCoder.defaultAbiCoder().encode(
                 ["uint256"],
                 [mockNode.tokenUnits[this.network.name]],
             );
         }
         async getFeeData() {
-            mockNode.feeAskedOn.push(this.network.name);
+            this.record("getFeeData");
+            if (mockNode.legacyFees) {
+                return {
+                    maxFeePerGas: null,
+                    maxPriorityFeePerGas: null,
+                    gasPrice: 10000000000n,
+                };
+            }
             return {
                 maxFeePerGas: 20000000000n,
                 maxPriorityFeePerGas: 1000000000n,
@@ -69,16 +96,22 @@ jest.mock("ethers", () => {
             return 21000n;
         }
         async getCode() {
+            this.record("getCode");
             return "0x";
         }
         async getTransactionCount() {
+            this.record("getTransactionCount");
             return 1;
         }
         async lookupAddress() {
             return null;
         }
         async broadcastTransaction(signed) {
-            mockNode.broadcast.push({ chainId: this.network.chainId, signed });
+            mockNode.broadcast.push({
+                chainId: this.network.chainId,
+                url: this.url,
+                signed,
+            });
             return { hash: "0x" + "ab".repeat(32) };
         }
     }
@@ -108,6 +141,8 @@ jest.mock("../src/popup/views/txStatus", () => ({
     showError: jest.fn(),
 }));
 
+// The Etherscan label check is its only caller here: the explorer pages it
+// asks for are recorded, and nothing is fetched.
 global.fetch = jest.fn(() => {
     throw new Error("tests must not perform network requests");
 });
@@ -154,7 +189,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const {
     BaseWallet,
@@ -164,18 +199,28 @@ const {
     parseEther,
 } = require("ethers");
 const { encryptWithPassword } = require("../src/shared/vault");
-const { state, loadState } = require("../src/shared/state");
+const { state, loadState, saveState } = require("../src/shared/state");
 const { onChainSwitch } = require("../src/shared/chainSwitch");
 const { NETWORKS } = require("../src/shared/networks");
+const { prices } = require("../src/shared/prices");
+const {
+    goBack,
+    pushCurrentView,
+    setBackRenderer,
+    showView,
+} = require("../src/popup/views/helpers");
+const {
+    makeBackRenderer,
+    resetRenderedViews,
+} = require("../src/popup/viewRouter");
 const txStatus = require("../src/popup/views/txStatus");
 const confirmTx = require("../src/popup/views/confirmTx");
 
 const PRIVATE_KEY = "0x" + "11".repeat(32);
 const HOLDER = new Wallet(PRIVATE_KEY).address;
 const RECIPIENT = "0xC0FfEE0000000000000000000000000000c0fFEe";
+const TOKEN = "0x7070707070707070707070707070707070707070";
 const PASSWORD = "correct horse battery staple";
-// A token with 6 decimal places, which the bundled list does not know.
-const TOKEN = "0x" + "d".repeat(40);
 
 function el(id) {
     return global.document.getElementById(id);
@@ -191,13 +236,15 @@ beforeAll(async () => {
 
 beforeEach(() => {
     elements.clear();
+    mockNode.asked = [];
     mockNode.balanceWei = {
         mainnet: parseEther("5"),
         sepolia: parseEther("5"),
     };
     mockNode.tokenUnits = { mainnet: 0n, sepolia: 0n };
-    mockNode.feeAskedOn = [];
     mockNode.broadcast = [];
+    mockNode.legacyFees = false;
+    global.fetch.mockClear();
     txStatus.showWait.mockClear();
     txStatus.showError.mockClear();
     signTransaction = jest.spyOn(BaseWallet.prototype, "signTransaction");
@@ -207,17 +254,16 @@ afterEach(() => {
     signTransaction.mockRestore();
 });
 
-// show() reads the balances and estimates the fee without awaiting either;
-// this lets both settle.
-async function settle() {
-    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+// Show the confirmation screen for 1 of the native token on `networkId`, or
+// for the transfer `changes` makes of it, as Review on the Send screen does,
+// with its balance read and its fee estimate settled.
+async function review(networkId, changes = {}) {
+    await onChainSwitch(networkId);
+    await reviewOnActiveNetwork(changes);
 }
 
-// Show the confirmation screen for 1 of the native token on `networkId`, or
-// for what `send` describes instead, as Review on the Send screen does, with
-// its balance read and its fee estimate settled.
-async function review(networkId, send = {}) {
-    await onChainSwitch(networkId);
+// review() on the network already active, without switching to it again.
+async function reviewOnActiveNetwork(changes = {}) {
     state.wallets = [
         {
             type: "key",
@@ -238,27 +284,101 @@ async function review(networkId, send = {}) {
         tokenSymbol: null,
         tokenDecimals: null,
         max: false,
-        ...send,
+        ...changes,
     });
     await settle();
 }
 
-// Switch the network to `networkId` as Settings in another popup does, then
-// open the popup again onto the confirmation screen it saved.
-async function reopenOn(networkId) {
-    const saved = JSON.parse(JSON.stringify(state.viewData));
-    await onChainSwitch(networkId);
+// The user's own node for a network, set in Settings.
+function ownNode(networkId) {
+    return "https://" + networkId + ".node.example.invalid";
+}
+
+// After review() on `reviewedOn`: the user's own node set for it, the Settings
+// gear, `switchedTo` chosen there, the popup closed and reopened onto
+// Settings, and Back, which draws the confirmation screen again from the
+// transaction it saved. The reopened page holds an ETH price of $2,000 and a
+// USDC price of $1 whichever network is active, so each USD value shows which
+// network it was priced for.
+async function switchReopenAndGoBack(reviewedOn, switchedTo) {
+    state.rpcUrl = ownNode(reviewedOn);
+    pushCurrentView();
+    showView("settings");
+    await onChainSwitch(switchedTo);
+
+    await loadState();
     elements.clear();
-    state.viewData = saved;
+    resetRenderedViews();
+    setBackRenderer(makeBackRenderer(state, { confirmTx }));
     confirmTx.init({});
-    confirmTx.restore();
+    prices.ETH = 2000;
+    prices.USDC = 1;
+    mockNode.asked = [];
+    global.fetch.mockClear();
+    goBack();
     await settle();
 }
 
+// The USD value `text` as the screen appends it for `networkId`: nothing on a
+// testnet, which has no USD values.
+function usdOn(networkId, text) {
+    return NETWORKS[networkId].isTestnet ? "" : " (" + text + ")";
+}
+
+// The screen for the transfer review() shows by default, described on
+// `networkId`: in its native currency, priced by it, linking to its explorer.
+function expectNativeTransferOn(networkId) {
+    const { nativeCurrency: symbol, explorerUrl } = NETWORKS[networkId];
+    expect(el("confirm-type").textContent).toBe(
+        "Native " + symbol + " transfer",
+    );
+    expect(el("confirm-amount").textContent).toBe(
+        "1.0000 " + symbol + usdOn(networkId, "$2,000.00"),
+    );
+    expect(el("confirm-balance").textContent).toBe(
+        "5.0000 " + symbol + usdOn(networkId, "$10,000.00"),
+    );
+    expect(el("confirm-fee-amount").textContent).toBe(
+        "~0.0002 " + symbol + usdOn(networkId, "$0.42"),
+    );
+    expect(el("confirm-fee-reserve").textContent).toBe(
+        "up to 0.0004 " + symbol + " reserved",
+    );
+    expect(el("confirm-gas-error").textContent).toBe(
+        "You do not have enough " +
+            symbol +
+            " to pay the network fee for this transfer. Please add " +
+            symbol +
+            " to this address and try again.",
+    );
+    expect(el("confirm-recipient-warning").textContent).toContain(
+        " holds no " + symbol + ". ",
+    );
+    expect(el("confirm-contract-warning").textContent).toContain(
+        " Sending " + symbol + " or tokens ",
+    );
+    expect(el("confirm-from").innerHTML).toContain(
+        `href="${explorerUrl}/address/${HOLDER}"`,
+    );
+    expect(el("confirm-to").innerHTML).toContain(
+        `href="${explorerUrl}/address/${RECIPIENT}"`,
+    );
+}
+
+// show() reads the balance and then estimates the fee, and checks the
+// recipient, without awaiting any of them; this lets all of them finish.
+async function settle() {
+    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+}
+
 function errors() {
     return el("confirm-errors").innerHTML;
 }
 
+function shown(id) {
+    return el(id).style.visibility === "visible";
+}
+
 function sendDisabled() {
     return el("btn-confirm-send").disabled;
 }
@@ -281,6 +401,25 @@ test("a transfer reviewed on Sepolia and sent goes out on Sepolia", async () =>
     expect(txStatus.showWait).toHaveBeenCalledTimes(1);
 });
 
+// Saving an RPC endpoint in Settings (src/popup/views/settings.js) sets only
+// state.rpcUrl: the endpoint remembered for the active network keeps its old
+// value until the next switch away from it.
+test("a transfer reviewed after the active network's RPC endpoint was changed in Settings asks the new endpoint", async () => {
+    const newNode = "https://new.node.example.invalid";
+    await onChainSwitch("sepolia");
+    state.rpcUrl = newNode;
+    await saveState();
+
+    await reviewOnActiveNetwork();
+
+    expect(mockNode.asked).toEqual([
+        { method: "getBalance", network: "sepolia", url: newNode },
+        { method: "getCode", network: "sepolia", url: newNode },
+        { method: "getTransactionCount", network: "sepolia", url: newNode },
+        { method: "getFeeData", network: "sepolia", url: newNode },
+    ]);
+});
+
 describe.each([
     ["sepolia", "mainnet", "SepoliaETH"],
     ["mainnet", "sepolia", "ETH"],
@@ -301,11 +440,219 @@ describe.each([
             expect(mockNode.broadcast).toEqual([]);
             expect(txStatus.showWait).not.toHaveBeenCalled();
             expect(txStatus.showError).not.toHaveBeenCalled();
-            expect(el("confirm-errors").style.visibility).toBe("visible");
-            expect(el("confirm-errors").innerHTML).toContain(
-                "The active network changed after this transaction was" +
-                    " reviewed, so it was not sent. Please go back and review" +
-                    " it again.",
+            expect(shown("confirm-network-changed-error")).toBe(true);
+            expect(shown("confirm-fee-bound-error")).toBe(false);
+        });
+    },
+);
+
+describe.each([
+    ["sepolia", "mainnet"],
+    ["mainnet", "sepolia"],
+])(
+    "a transfer reviewed on %s, with %s chosen in Settings, the popup reopened and Back pressed",
+    (reviewedOn, switchedTo) => {
+        const { nativeCurrency: symbol, explorerUrl } = NETWORKS[reviewedOn];
+
+        test("is described on the network it was reviewed for, and neither signed nor sent", async () => {
+            await review(reviewedOn);
+            await switchReopenAndGoBack(reviewedOn, switchedTo);
+
+            expect(state.currentView).toBe("confirm-tx");
+            expectNativeTransferOn(reviewedOn);
+            expect(mockNode.asked).toEqual([
+                {
+                    method: "getBalance",
+                    network: reviewedOn,
+                    url: ownNode(reviewedOn),
+                },
+                {
+                    method: "getCode",
+                    network: reviewedOn,
+                    url: ownNode(reviewedOn),
+                },
+                {
+                    method: "getTransactionCount",
+                    network: reviewedOn,
+                    url: ownNode(reviewedOn),
+                },
+                {
+                    method: "getFeeData",
+                    network: reviewedOn,
+                    url: ownNode(reviewedOn),
+                },
+            ]);
+            expect(global.fetch.mock.calls.map(([url]) => url)).toEqual([
+                explorerUrl + "/address/" + RECIPIENT,
+            ]);
+            expect(el("btn-confirm-send").disabled).toBe(false);
+
+            await signAndSend();
+
+            expect(signTransaction).not.toHaveBeenCalled();
+            expect(mockNode.broadcast).toEqual([]);
+            expect(txStatus.showWait).not.toHaveBeenCalled();
+            expect(txStatus.showError).not.toHaveBeenCalled();
+            expect(shown("confirm-network-changed-error")).toBe(true);
+        });
+
+        test("is sent on that network, as described, once it is chosen in Settings again and Back pressed", async () => {
+            await review(reviewedOn);
+            await switchReopenAndGoBack(reviewedOn, switchedTo);
+            // The Settings gear, the reviewed network chosen, and Back, which
+            // only unhides the screen as it was drawn.
+            pushCurrentView();
+            showView("settings");
+            await onChainSwitch(reviewedOn);
+            goBack();
+
+            expect(state.currentView).toBe("confirm-tx");
+            expectNativeTransferOn(reviewedOn);
+
+            await signAndSend();
+
+            const chainId = BigInt(NETWORKS[reviewedOn].chainId);
+            expect(mockNode.broadcast).toHaveLength(1);
+            expect(mockNode.broadcast[0].chainId).toBe(chainId);
+            expect(mockNode.broadcast[0].url).toBe(ownNode(reviewedOn));
+            expect(Transaction.from(mockNode.broadcast[0].signed).chainId).toBe(
+                chainId,
+            );
+            expect(txStatus.showWait).toHaveBeenCalledTimes(1);
+        });
+
+        test("for more than the balance, says so in that network's native currency", async () => {
+            await review(reviewedOn, { amount: "10" });
+            await switchReopenAndGoBack(reviewedOn, switchedTo);
+
+            expect(shown("confirm-balance-error")).toBe(true);
+            expect(el("confirm-balance-error").textContent).toBe(
+                "Your " +
+                    symbol +
+                    " balance does not cover this amount. Please go back and" +
+                    " send a smaller amount.",
+            );
+        });
+
+        test("states and checks that network's balance as it is then, which no longer covers the send", async () => {
+            await review(reviewedOn);
+            expect(sendDisabled()).toBe(false);
+            mockNode.balanceWei = {
+                [reviewedOn]: parseEther("0.5"),
+                [switchedTo]: parseEther("5"),
+            };
+            await switchReopenAndGoBack(reviewedOn, switchedTo);
+
+            expect(el("confirm-balance").textContent).toBe(
+                "0.5000 " + symbol + usdOn(reviewedOn, "$1,000.00"),
+            );
+            expect(shown("confirm-balance-error")).toBe(true);
+            expect(sendDisabled()).toBe(true);
+        });
+
+        test("states and checks that network's balance as it is then, which now covers the send, and refuses to send it", async () => {
+            mockNode.balanceWei[reviewedOn] = parseEther("0.5");
+            await review(reviewedOn);
+            expect(sendDisabled()).toBe(true);
+            mockNode.balanceWei = {
+                [reviewedOn]: parseEther("5"),
+                [switchedTo]: parseEther("0.5"),
+            };
+            await switchReopenAndGoBack(reviewedOn, switchedTo);
+
+            expect(el("confirm-balance").textContent).toBe(
+                "5.0000 " + symbol + usdOn(reviewedOn, "$10,000.00"),
+            );
+            expect(errors()).toBe("");
+            expect(shown("confirm-balance-error")).toBe(false);
+            expect(shown("confirm-amount-fee-error")).toBe(false);
+            expect(sendDisabled()).toBe(false);
+
+            await signAndSend();
+
+            expect(signTransaction).not.toHaveBeenCalled();
+            expect(mockNode.broadcast).toEqual([]);
+            expect(shown("confirm-network-changed-error")).toBe(true);
+        });
+
+        const tokenSend = {
+            token: TOKEN,
+            tokenSymbol: "TOK",
+            tokenDecimals: 6,
+        };
+
+        test("of a token, states and checks that network's token balance as it is then, which no longer covers the send", async () => {
+            mockNode.tokenUnits[reviewedOn] = 10000000n;
+            await review(reviewedOn, tokenSend);
+            expect(sendDisabled()).toBe(false);
+            mockNode.tokenUnits = {
+                [reviewedOn]: 500000n,
+                [switchedTo]: 10000000n,
+            };
+            await switchReopenAndGoBack(reviewedOn, switchedTo);
+
+            expect(el("confirm-balance").textContent).toBe("0.5000 TOK");
+            expect(shown("confirm-balance-error")).toBe(true);
+            expect(el("confirm-balance-error").textContent).toBe(
+                "Your TOK balance does not cover this amount. Please go back" +
+                    " and send a smaller amount.",
+            );
+            expect(sendDisabled()).toBe(true);
+        });
+
+        test("of a token, states and checks that network's token balance as it is then, which now covers the send, and refuses to send it", async () => {
+            await review(reviewedOn, tokenSend);
+            expect(sendDisabled()).toBe(true);
+            mockNode.tokenUnits = {
+                [reviewedOn]: 10000000n,
+                [switchedTo]: 0n,
+            };
+            await switchReopenAndGoBack(reviewedOn, switchedTo);
+
+            expect(el("confirm-balance").textContent).toBe("10.0000 TOK");
+            expect(errors()).toBe("");
+            expect(shown("confirm-balance-error")).toBe(false);
+            expect(shown("confirm-gas-error")).toBe(false);
+            expect(sendDisabled()).toBe(false);
+
+            await signAndSend();
+
+            expect(signTransaction).not.toHaveBeenCalled();
+            expect(mockNode.broadcast).toEqual([]);
+            expect(shown("confirm-network-changed-error")).toBe(true);
+        });
+
+        test("with a fee quoted by a node with no type-2 pricing, shows the fee in that network's native currency and price", async () => {
+            await review(reviewedOn);
+            mockNode.legacyFees = true;
+            await switchReopenAndGoBack(reviewedOn, switchedTo);
+
+            expect(el("confirm-fee-amount").textContent).toBe(
+                "0.0002 " + symbol + usdOn(reviewedOn, "$0.42"),
+            );
+        });
+
+        test("of an ERC-20 token, links the token contract to that network's explorer and prices the token by that network", async () => {
+            mockNode.tokenUnits[reviewedOn] = 50000000n;
+            await review(reviewedOn, {
+                token: TOKEN,
+                tokenSymbol: "USDC",
+                tokenDecimals: 6,
+                amount: "10",
+            });
+            await switchReopenAndGoBack(reviewedOn, switchedTo);
+
+            expect(el("confirm-type").textContent).toBe(
+                "ERC-20 token transfer (USDC)",
+            );
+            expect(el("confirm-token-contract").innerHTML).toContain(
+                `href="${explorerUrl}/address/${TOKEN}"`,
+            );
+            expect(el("confirm-amount").textContent).toBe(
+                "10.0000 USDC" + usdOn(reviewedOn, "$10.00"),
+            );
+            expect(el("confirm-balance").textContent).toBe(
+                "50.0000 USDC" + usdOn(reviewedOn, "$50.00"),
             );
         });
     },
@@ -331,79 +678,6 @@ test("the send is refused by a signer on another network's node", async () => {
     expect(mockNode.broadcast).toEqual([]);
 });
 
-describe("a confirmation screen saved on mainnet and reopened after a switch to Sepolia", () => {
-    test("states and checks the Sepolia balance, which covers the send", async () => {
-        mockNode.balanceWei = {
-            mainnet: parseEther("0.5"),
-            sepolia: parseEther("5"),
-        };
-        await review("mainnet");
-        expect(el("confirm-balance").textContent).toBe("0.5000 ETH");
-        expect(sendDisabled()).toBe(true);
-
-        await reopenOn("sepolia");
-        expect(el("confirm-type").textContent).toBe(
-            "Native SepoliaETH transfer",
-        );
-        expect(el("confirm-balance").textContent).toBe("5.0000 SepoliaETH");
-        expect(errors()).toBe("");
-        expect(el("confirm-amount-fee-error").style.visibility).toBe("hidden");
-        expect(sendDisabled()).toBe(false);
-    });
-
-    test("states and checks the Sepolia balance, which does not cover the send", async () => {
-        mockNode.balanceWei = {
-            mainnet: parseEther("5"),
-            sepolia: parseEther("0.5"),
-        };
-        await review("mainnet");
-        expect(el("confirm-balance").textContent).toBe("5.0000 ETH");
-        expect(sendDisabled()).toBe(false);
-
-        await reopenOn("sepolia");
-        expect(el("confirm-balance").textContent).toBe("0.5000 SepoliaETH");
-        expect(errors()).toContain(
-            "Insufficient balance. You have 0.5000 SepoliaETH but are trying" +
-                " to send 1 SepoliaETH.",
-        );
-        expect(sendDisabled()).toBe(true);
-    });
-
-    const tokenSend = {
-        token: TOKEN,
-        tokenSymbol: "TOK",
-        tokenDecimals: 6,
-    };
-
-    test("states and checks the Sepolia token balance, which covers the send", async () => {
-        mockNode.tokenUnits = { mainnet: 0n, sepolia: 10000000n };
-        await review("mainnet", tokenSend);
-        expect(el("confirm-balance").textContent).toBe("0.0000 TOK");
-        expect(sendDisabled()).toBe(true);
-
-        await reopenOn("sepolia");
-        expect(el("confirm-balance").textContent).toBe("10.0000 TOK");
-        expect(errors()).toBe("");
-        expect(el("confirm-gas-error").style.visibility).toBe("hidden");
-        expect(sendDisabled()).toBe(false);
-    });
-
-    test("states and checks the Sepolia token balance, which does not cover the send", async () => {
-        mockNode.tokenUnits = { mainnet: 10000000n, sepolia: 500000n };
-        await review("mainnet", tokenSend);
-        expect(el("confirm-balance").textContent).toBe("10.0000 TOK");
-        expect(sendDisabled()).toBe(false);
-
-        await reopenOn("sepolia");
-        expect(el("confirm-balance").textContent).toBe("0.5000 TOK");
-        expect(errors()).toContain(
-            "Insufficient TOK balance. You have 0.5000 TOK but are trying to" +
-                " send 1 TOK.",
-        );
-        expect(sendDisabled()).toBe(true);
-    });
-});
-
 describe("the balance read", () => {
     test("leaves the balance line Loading... and Sign & Send disabled until it returns", async () => {
         let answer;
@@ -418,6 +692,8 @@ describe("the balance read", () => {
         expect(el("confirm-balance").textContent).toBe("Loading...");
         expect(el("confirm-fee-amount").textContent).toBe("Estimating...");
         expect(el("confirm-errors").style.visibility).toBe("hidden");
+        expect(shown("confirm-balance-error")).toBe(false);
+        expect(shown("confirm-balance-read-error")).toBe(false);
         expect(sendDisabled()).toBe(true);
 
         answer(parseEther("5"));
@@ -426,8 +702,34 @@ describe("the balance read", () => {
         expect(sendDisabled()).toBe(false);
     });
 
-    // The fee is estimated once the read returns, so a node chosen then would
-    // be the new network's.
+    // The Chrome suite measures that nothing moves; this checks the message
+    // is already written, only hidden, before the read returns.
+    test("that finds the amount not covered only makes a message written before it visible", async () => {
+        let answer;
+        const getBalance = jest
+            .spyOn(JsonRpcProvider.prototype, "getBalance")
+            .mockImplementationOnce(() => new Promise((r) => (answer = r)));
+        try {
+            await review("sepolia");
+        } finally {
+            getBalance.mockRestore();
+        }
+        const message =
+            "Your SepoliaETH balance does not cover this amount. Please go" +
+            " back and send a smaller amount.";
+        expect(el("confirm-balance-error").textContent).toBe(message);
+        expect(shown("confirm-balance-error")).toBe(false);
+
+        answer(parseEther("0.5"));
+        await settle();
+        expect(el("confirm-balance-error").textContent).toBe(message);
+        expect(shown("confirm-balance-error")).toBe(true);
+        expect(errors()).toBe("");
+        expect(sendDisabled()).toBe(true);
+    });
+
+    // The fee is estimated once the read returns, after the switch, and still
+    // asks the node of the network the screen was drawn for.
     test("still in flight when Sepolia is chosen in Settings leaves the balance and the fee on mainnet", async () => {
         let answer;
         const getBalance = jest
@@ -438,13 +740,17 @@ describe("the balance read", () => {
         } finally {
             getBalance.mockRestore();
         }
-        expect(mockNode.feeAskedOn).toEqual([]);
+        const feeAskedOn = () =>
+            mockNode.asked
+                .filter((q) => q.method === "getFeeData")
+                .map((q) => q.network);
+        expect(feeAskedOn()).toEqual([]);
 
         await onChainSwitch("sepolia");
         answer(parseEther("5"));
         await settle();
 
-        expect(mockNode.feeAskedOn).toEqual(["mainnet"]);
+        expect(feeAskedOn()).toEqual(["mainnet"]);
         expect(el("confirm-balance").textContent).toBe("5.0000 ETH");
         // 21000 gas at 10 gwei expected, at 20 gwei reserved.
         expect(el("confirm-fee-amount").textContent).toBe("~0.0002 ETH");
@@ -463,11 +769,9 @@ describe("the balance read", () => {
             getBalance.mockRestore();
         }
         expect(el("confirm-balance").textContent).toBe("unknown (SepoliaETH)");
-        expect(errors()).toBe(
-            '<div class="text-xs">Your balance could not be read from the' +
-                " network, so this transaction cannot be checked against it." +
-                " Please go back and try again.</div>",
-        );
+        expect(shown("confirm-balance-read-error")).toBe(true);
+        expect(shown("confirm-balance-error")).toBe(false);
+        expect(errors()).toBe("");
         expect(sendDisabled()).toBe(true);
     });
 });

tests/contractCreation.test.js

@@ -192,6 +192,7 @@ describe("the wait, success and error screens", () => {
         amount: "0.0000",
         token: "ETH",
         tokenSymbol: null,
+        chainId: "0x1",
     };
     const transfer = { ...creation, to: RECIPIENT };
 

tests/deleteWalletLostPassword.test.js

@@ -259,6 +259,36 @@ describe("reaching the screen", () => {
     });
 });
 
+// Both screens tell the user what they need to get the wallet back, and a
+// key or xprv wallet has no recovery phrase: telling its owner to rely on
+// one sends them looking for words that do not exist
+// (https://git.eeqj.de/sneak/AutistMask/issues/529).
+describe("what the screens say the wallet's backup is", () => {
+    test.each([
+        ["hd", "recovery phrase"],
+        ["key", "private key"],
+        ["xprv", "extended private key"],
+    ])(
+        "a wallet of type %s is told about its %s",
+        async (type, keyMaterial) => {
+            const { deleteWallet, state } = load();
+            state.wallets[1].type = type;
+
+            deleteWallet.show(1);
+            expect(state.currentView).toBe("delete-wallet-confirm");
+            expect(node("delete-wallet-key-material").textContent).toBe(
+                keyMaterial,
+            );
+
+            await click("btn-delete-wallet-lost-password");
+            expect(state.currentView).toBe(VIEW);
+            expect(node("delete-wallet-lost-key-material").textContent).toBe(
+                keyMaterial,
+            );
+        },
+    );
+});
+
 describe("the typed confirmation", () => {
     test("a name that is not the wallet's deletes nothing", async () => {
         const { deleteWallet, state, storage } = load();

tests/dustThreshold.test.js

@@ -101,7 +101,7 @@ describe("the flash line the message is shown in", () => {
     //
     // 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
+    // measure that, in a real browser at the documented 396x600 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

tests/e2e/network.js

@@ -226,8 +226,9 @@ const RPC_RESULTS = {
 // The "latest" block, which ethers' getFeeData() reads baseFeePerGas from
 // to derive maxFeePerGas. Without it every fee is a legacy gasPrice, the
 // reserve and the estimate collapse to the same number, and the gate tests
-// stop being able to distinguish them.
-function latestBlock() {
+// stop being able to distinguish them. opts.baseFeeWei replaces its base fee,
+// read at request time like every other fixture switch.
+function latestBlock(opts) {
     return {
         hash: "0x" + "11".repeat(32),
         parentHash: "0x" + "22".repeat(32),
@@ -239,7 +240,7 @@ function latestBlock() {
         gasUsed: "0xf4240",
         miner: STUB_COUNTERPARTY,
         extraData: "0x",
-        baseFeePerGas: hex(BASE_FEE_WEI),
+        baseFeePerGas: opts.baseFeeWei || hex(BASE_FEE_WEI),
         transactions: [],
     };
 }
@@ -428,9 +429,10 @@ const HOLD_MAX_MS = 30000;
 
 // Hold a reply open for as long as the test asks: until opts[name] is false.
 //
-// The switch (holdGasEstimate, holdTransactionCount or holdBlockscout) is read
-// here rather than captured, so a test flips it on the same options object the
-// route was registered with — the same pattern as seedTokenTransfer. This is
+// The switch (holdBalance, holdGasEstimate, holdTransactionCount or
+// holdBlockscout) is read here rather than captured, so a test flips it on the
+// same options object the route was registered with — the same pattern as
+// seedTokenTransfer. This is
 // the only way to observe a screen while its request is genuinely in flight;
 // sampling the screen and hoping to win a race against the network would
 // assert nothing on a slow machine.
@@ -480,7 +482,7 @@ function rpcReply(req, opts, report) {
         });
     }
     if (req.method === "eth_getBlockByNumber") {
-        return Object.assign(envelope, { result: latestBlock() });
+        return Object.assign(envelope, { result: latestBlock(opts) });
     }
     // The end of the dApp transaction round trip: the raw signed transaction
     // the background hands to the node. It is recorded verbatim so a test can
@@ -565,6 +567,9 @@ async function handleRpc(route, postData, opts, report) {
         report("unstubbed request: POST " + route.request().url());
         return route.abort();
     }
+    if (batch.some((req) => req.method === "eth_getBalance")) {
+        await awaitRelease(opts, "holdBalance", report);
+    }
     if (batch.some((req) => req.method === "eth_estimateGas")) {
         await awaitRelease(opts, "holdGasEstimate", report);
     }
@@ -621,8 +626,12 @@ function traceEnabled(raw) {
  * @param {string} [opts.ethBalanceWei]  hex wei answered to eth_getBalance;
  *   defaults to zero, which is what every test that predates the funded
  *   fixture expects.
+ * @param {string} [opts.baseFeeWei]  hex wei answered as the latest block's
+ *   baseFeePerGas; defaults to BASE_FEE_WEI. Read at request time.
  * @param {boolean} [opts.failGasEstimate]  answer eth_estimateGas with a
  *   node-side refusal.
+ * @param {boolean} [opts.holdBalance]  hold every batch containing an
+ *   eth_getBalance until this is cleared again.
  * @param {boolean} [opts.holdGasEstimate]  hold every batch containing an
  *   eth_estimateGas until this is cleared again.
  * @param {boolean} [opts.holdTransactionCount]  hold every batch containing an

tests/e2e/run.js

@@ -60,6 +60,14 @@ const TEST_TIMEOUT_MS = 120000;
 // trailing drain in main().
 const TRAILING_WATCH_MS = 1500;
 
+// The popup's size, as README gives it: `body` in src/popup/styles/main.css
+// is 396px wide, and src/background/index.js opens an approval window at
+// the same 396x600. Pages in this context otherwise get Playwright's
+// 1280x720 default, where the page never scrolls sideways and a button
+// below the popup's fold is still on screen, so a layout measured there
+// passes whatever the page does.
+const POPUP_VIEWPORT = { width: 396, height: 600 };
+
 const tests = [];
 
 function test(name, fn) {
@@ -359,11 +367,14 @@ async function leaveTransactionDetail(page) {
     await openAddressDetail(page);
 }
 
-// Back out to Home from wherever the previous test finished.
+// Back out to Home from wherever the previous test finished, and wait for the
+// save that navigation makes, so a test reading the stored stack next reads
+// the one Home left.
 async function goHome(page) {
     await leaveTransactionDetail(page);
     await page.click("#btn-address-back");
     await visible(page, "#view-main");
+    await waitForPersisted(page, "currentView", "main", "back on Home");
 }
 
 // One field of the popup's state as it was actually persisted, read out of
@@ -1824,13 +1835,66 @@ test("the Settings assertions above all ran (#229)", async (env) => {
     );
 });
 
-// ------------------------------------------------ dust threshold (#233)
+// ------------------------------------------------ testnet banner (#511)
 
-// The popup size README documents the UI as designed for. Pages in this
-// context otherwise get Playwright's 1280x720 default, at which the flash
-// line has room for any plausible message and never wraps — measuring
-// there would pass for every string and prove nothing.
-const POPUP_VIEWPORT = { width: 360, height: 600 };
+// This suite runs a release build, so the red banner at the top reads
+// "[TESTNET]" on Sepolia and is absent on mainnet. A network switch in
+// Settings must change it while Settings is still on screen; it used to
+// change only when the next screen came up
+// (https://git.eeqj.de/sneak/AutistMask/issues/511).
+
+// The banner's text, or null when there is none, once the switch to `net`
+// has finished. The switch's flash is the last thing its handler does, and
+// showView() clears the flash, so the banner read while that flash is up is
+// the one the switch left on the screen it was made from.
+async function bannerAfterSwitch(page, net) {
+    await page.waitForFunction(
+        (text) => document.getElementById("flash-msg").textContent === text,
+        "Switched to " + net.name + ".",
+    );
+    return page.evaluate(() => {
+        const banner = document.getElementById("debug-banner");
+        return {
+            text: banner === null ? null : banner.textContent,
+            onSettings: !document
+                .getElementById("view-settings")
+                .classList.contains("hidden"),
+        };
+    });
+}
+
+test("a network switch in Settings shows and removes the testnet banner at once (#511)", async (env) => {
+    const { mainnet, sepolia } = NETWORKS;
+    await openSettings(env.page);
+    assert(
+        (await env.page.locator("#debug-banner").count()) === 0,
+        "a banner is up on mainnet before the switch",
+    );
+
+    await env.page.selectOption("#settings-network", "sepolia");
+    let after = await bannerAfterSwitch(env.page, sepolia);
+    assert(after.onSettings, "Settings left the screen on the switch");
+    assert(
+        after.text === "[TESTNET]",
+        "after the switch to Sepolia, Settings shows the banner " +
+            JSON.stringify(after.text) +
+            ', expected "[TESTNET]"',
+    );
+
+    await env.page.selectOption("#settings-network", "mainnet");
+    after = await bannerAfterSwitch(env.page, mainnet);
+    assert(after.onSettings, "Settings left the screen on the switch back");
+    assert(
+        after.text === null,
+        "after the switch back to mainnet, Settings still shows the banner " +
+            JSON.stringify(after.text),
+    );
+
+    await env.page.click("#btn-settings-back");
+    await visible(env.page, "#view-main");
+});
+
+// ------------------------------------------------ dust threshold (#233)
 
 // Everything below the flash line that must not move when it fills, plus
 // the height of the line itself. Runs in the page.
@@ -2080,7 +2144,7 @@ test("a password error moves nothing on any screen (#297)", async (env) => {
 
 // ------------------------------------------ add wallet Import button (#493)
 
-// At 360x600 the add wallet screen's Import button already starts near the
+// At 396x600 the add wallet screen's Import button already starts near the
 // bottom of the popup, so its password error line sits beside the button
 // rather than above it. Measures the button and the line empty and again
 // filled with the longest error addWallet.js puts there. Runs in the page.
@@ -2232,7 +2296,8 @@ function feeEth(wei) {
 
 // What the confirmation screen is showing right now, read out of the DOM in
 // one pass: whether sending is allowed, which reason it is giving, what the
-// fee block says, and how tall the whole view is.
+// fee block says, how tall the whole view is, and where the password field and
+// Sign & Send sit in it.
 async function confirmState(page) {
     return page.evaluate(() => {
         const el = (id) => document.getElementById(id);
@@ -2245,6 +2310,12 @@ async function confirmState(page) {
         };
         return {
             height: el("view-confirm-tx").getBoundingClientRect().height,
+            passwordTop:
+                el("confirm-tx-password").getBoundingClientRect().top -
+                el("view-confirm-tx").getBoundingClientRect().top,
+            sendTop:
+                el("btn-confirm-send").getBoundingClientRect().top -
+                el("view-confirm-tx").getBoundingClientRect().top,
             type: el("confirm-type").textContent.trim(),
             balance: el("confirm-balance").textContent.trim(),
             fee: el("confirm-fee-amount").textContent.trim(),
@@ -2253,9 +2324,18 @@ async function confirmState(page) {
             errors: shown("confirm-errors")
                 ? el("confirm-errors").textContent.trim()
                 : "",
+            balanceError: shown("confirm-balance-error")
+                ? el("confirm-balance-error").textContent.trim()
+                : "",
             amountFeeError: shown("confirm-amount-fee-error"),
             gasError: shown("confirm-gas-error"),
             feeUnknownError: shown("confirm-fee-unknown-error"),
+            // Its sentence is wrapped across lines in index.html.
+            feeBoundError: shown("confirm-fee-bound-error")
+                ? el("confirm-fee-bound-error")
+                      .textContent.replace(/\s+/g, " ")
+                      .trim()
+                : "",
             sendDisabled: el("btn-confirm-send").disabled,
         };
     });
@@ -2271,6 +2351,16 @@ async function waitForEstimate(page) {
     );
 }
 
+async function waitForBalance(page) {
+    await page.waitForFunction(
+        () =>
+            document.getElementById("confirm-balance").textContent.trim() !==
+            "Loading...",
+        null,
+        { timeout: 60000 },
+    );
+}
+
 async function backToAddress(page) {
     if (await page.isVisible("#view-confirm-tx")) {
         await page.click("#btn-confirm-back");
@@ -2282,13 +2372,14 @@ async function backToAddress(page) {
     await openAddressDetail(page);
 }
 
-// Drive the popup to the confirmation screen for one send.
+// Drive the popup to the confirmation screen for one send, and return as soon
+// as the screen is shown, its balance read still in flight.
 //
 // It waits for the send screen to be showing `balance`, the fixture's balance
 // as that screen displays it, before filling anything in. Waiting for it —
 // rather than for a refresh to have probably landed — is what keeps every
 // assertion below deterministic after a fixture change.
-async function goToConfirm(page, { token, balance, amount }) {
+async function openConfirm(page, { token, balance, amount }) {
     await backToAddress(page);
     await page.click("#btn-send");
     await visible(page, "#view-send");
@@ -2303,16 +2394,14 @@ async function goToConfirm(page, { token, balance, amount }) {
     await page.fill("#send-amount", amount);
     await page.click("#btn-send-review");
     await visible(page, "#view-confirm-tx");
-    // The screen reads the balance itself before it estimates the fee, so
-    // waiting for it here means every state below is read with the balance
-    // in place, the pending fee included.
-    await page.waitForFunction(
-        () =>
-            document.getElementById("confirm-balance").textContent.trim() !==
-            "Loading...",
-        null,
-        { timeout: 60000 },
-    );
+}
+
+// The same, returning once the screen has read the balance. It reads it
+// before it estimates the fee, so every state below is read with the balance
+// in place, the pending fee included.
+async function goToConfirm(page, send) {
+    await openConfirm(page, send);
+    await waitForBalance(page);
     await assertAddressesFit(page, "the confirmation screen");
 }
 
@@ -2388,7 +2477,10 @@ test("ConfirmTx blocks sending while the fee estimate is pending (#238)", async
         "the estimate-failed message is shown for an estimate that is merely pending",
     );
     assert(
-        !st.amountFeeError && !st.gasError && st.errors === "",
+        !st.amountFeeError &&
+            !st.gasError &&
+            st.errors === "" &&
+            st.balanceError === "",
         "a balance message is shown before the fee is known",
     );
 });
@@ -2419,6 +2511,7 @@ test("ConfirmTx enables Send once the estimate lands, quoting both numbers (#238
     );
     assert(
         st.errors === "" &&
+            st.balanceError === "" &&
             !st.amountFeeError &&
             !st.gasError &&
             !st.feeUnknownError,
@@ -2485,30 +2578,54 @@ test("ConfirmTx gates on the fee RESERVE, not the displayed estimate (#238)", as
     );
 });
 
-test("ConfirmTx refuses a send that exceeds the balance outright (#238)", async (env) => {
-    await goToConfirm(env.page, {
-        token: "ETH",
-        balance: FUNDED_ETH_TEXT + " ETH",
-        amount: OVER_BALANCE_AMOUNT,
-    });
+// The screen is first measured with its balance read held, so the message the
+// read brings must already hold its space when the read returns (#558).
+test("ConfirmTx refuses a send that exceeds the balance outright, and nothing moves when the balance arrives (#238)", async (env) => {
+    env.routeOpts.holdBalance = true;
+    let reading;
+    try {
+        await openConfirm(env.page, {
+            token: "ETH",
+            balance: FUNDED_ETH_TEXT + " ETH",
+            amount: OVER_BALANCE_AMOUNT,
+        });
+        reading = await confirmState(env.page);
+    } finally {
+        env.routeOpts.holdBalance = false;
+    }
+    assert(
+        reading.balance === "Loading...",
+        "the balance read was not held: " + JSON.stringify(reading.balance),
+    );
+    await waitForBalance(env.page);
     await waitForEstimate(env.page);
 
     const st = await confirmState(env.page);
-    const want =
-        "Insufficient balance. You have " +
-        FUNDED_ETH_TEXT +
-        " ETH but are trying to send " +
-        OVER_BALANCE_AMOUNT +
-        " ETH.";
     assert(
-        st.errors === want,
-        "wrong over-balance message: " + JSON.stringify(st.errors),
+        st.balance === FUNDED_ETH_TEXT + " ETH",
+        "the confirmation screen shows the wrong balance: " +
+            JSON.stringify(st.balance),
+    );
+    const want =
+        "Your ETH balance does not cover this amount. Please go back and" +
+        " send a smaller amount.";
+    assert(
+        st.balanceError === want,
+        "wrong over-balance message: " + JSON.stringify(st.balanceError),
     );
     assert(st.sendDisabled, "Send is enabled for a send that exceeds balance");
     assert(
         !st.amountFeeError,
         "the amount-plus-fee message is shown for an amount that alone exceeds the balance",
     );
+    assert(
+        st.sendTop === reading.sendTop,
+        "Sign & Send moved when the balance read returned: " +
+            reading.sendTop +
+            "px -> " +
+            st.sendTop +
+            "px",
+    );
 });
 
 test("ConfirmTx refuses to send when the fee estimate fails, with its own message (#238)", async (env) => {
@@ -2552,7 +2669,10 @@ test("ConfirmTx refuses to send when the fee estimate fails, with its own messag
             "the estimate-failed message is not shown after a failed estimate",
         );
         assert(
-            !st.amountFeeError && !st.gasError && st.errors === "",
+            !st.amountFeeError &&
+                !st.gasError &&
+                st.errors === "" &&
+                st.balanceError === "",
             "a balance message is shown for an estimate that simply failed",
         );
         assert(
@@ -2643,21 +2763,19 @@ test("ConfirmTx refuses an ERC-20 send that exceeds the token balance (#238)", a
     await waitForEstimate(env.page);
 
     const st = await confirmState(env.page);
-    const want =
-        "Insufficient " +
-        STUB_TOKEN.symbol +
-        " balance. You have " +
-        TOKEN_BALANCE_TEXT +
-        " " +
-        STUB_TOKEN.symbol +
-        " but are trying to send " +
-        OVER_TOKEN_AMOUNT +
-        " " +
-        STUB_TOKEN.symbol +
-        ".";
     assert(
-        st.errors === want,
-        "wrong over-token-balance message: " + JSON.stringify(st.errors),
+        st.balance === TOKEN_BALANCE_TEXT + " " + STUB_TOKEN.symbol,
+        "the confirmation screen shows the wrong token balance: " +
+            JSON.stringify(st.balance),
+    );
+    const want =
+        "Your " +
+        STUB_TOKEN.symbol +
+        " balance does not cover this amount. Please go back and send a" +
+        " smaller amount.";
+    assert(
+        st.balanceError === want,
+        "wrong over-token-balance message: " + JSON.stringify(st.balanceError),
     );
     assert(
         st.sendDisabled,
@@ -2713,9 +2831,9 @@ test("ConfirmTx gates the ERC-20 fee on the RESERVE, with the ERC-20 message (#2
         "the native-ETH over-budget message is shown on an ERC-20 transfer",
     );
     assert(
-        st.errors === "",
+        st.errors === "" && st.balanceError === "",
         "a token-balance message is shown for a transfer the token balance covers: " +
-            JSON.stringify(st.errors),
+            JSON.stringify(st.errors + st.balanceError),
     );
     assert(
         st.height === env.erc20PendingHeight,
@@ -2861,9 +2979,10 @@ async function goToTokenConfirm(env) {
         amount: TOKEN_AMOUNT,
     });
     await waitForEstimate(env.page);
+    // TOKEN_AMOUNT to four decimal places (README.md, Display Consistency).
     const shown = await shownAmount(env.page);
     assert(
-        shown === TOKEN_AMOUNT + " " + STUB_TOKEN.symbol,
+        shown === "0.2500 " + STUB_TOKEN.symbol,
         "the confirmation screen is not showing the amount that was entered: " +
             JSON.stringify(shown),
     );
@@ -3013,6 +3132,210 @@ test("a token that lies about decimals() at signing time broadcasts nothing (#30
     }
 });
 
+// ------------------------- a send Sign & Send refuses moves nothing (#583)
+//
+// README, No Layout Shift. Sign & Send refuses a send on the confirmation
+// screen when the active network changed since review and when its gas limit
+// or fee is over its bound, and each refusal's sentence sits in a box that held
+// its space from the first paint. This drives the total fee refusal, the longer
+// of the two sentences.
+
+// The base fee the stub node quotes once Sign & Send is pressed. ethers asks
+// twice it plus the 1 gwei priority fee per gas, 50,001 gwei, so the 21,000-gas
+// send would allow a fee of about 1.05 ETH, over the 1 ETH this wallet signs
+// for (MAX_TOTAL_FEE in src/shared/approvalVerify.js).
+const OVER_BOUND_BASE_FEE_WEI = 25000n * 10n ** 9n;
+
+test("a send refused for its fee leaves the password field and Sign & Send where they were (#583)", async (env) => {
+    env.errors.expect("confirmTx logging the refused send", /send refused/);
+    try {
+        await goToConfirm(env.page, {
+            token: "ETH",
+            balance: FUNDED_ETH_TEXT + " ETH",
+            amount: COMFORTABLE_AMOUNT,
+        });
+        await waitForEstimate(env.page);
+        const before = await confirmState(env.page);
+        assert(
+            !before.sendDisabled && before.feeBoundError === "",
+            "the screen is not ready to send: " + JSON.stringify(before),
+        );
+
+        // Only now, with the screen drawn and its fee estimated, does the
+        // node quote a fee over the bound.
+        env.routeOpts.baseFeeWei = toHexWei(OVER_BOUND_BASE_FEE_WEI);
+        const sent = env.routeOpts.broadcastTransactions.length;
+        await fillPasswordAndSend(env.page);
+        await env.page.waitForFunction(
+            () =>
+                getComputedStyle(
+                    document.getElementById("confirm-fee-bound-error"),
+                ).visibility === "visible",
+            null,
+            { timeout: 60000 },
+        );
+        const after = await confirmState(env.page);
+
+        // Printed pass or fail, as the dust threshold test does.
+        console.log(
+            "# refused send: password field top " +
+                before.passwordTop +
+                " -> " +
+                after.passwordTop +
+                "px, Sign & Send top " +
+                before.sendTop +
+                " -> " +
+                after.sendTop +
+                "px",
+        );
+        assert(
+            env.routeOpts.broadcastTransactions.length === sent,
+            "a send over the fee bound reached the RPC",
+        );
+        assert(
+            after.feeBoundError ===
+                "The gas limit or fee the RPC endpoint quoted for this" +
+                    " transaction is more than this wallet will sign for, so" +
+                    " it was not sent. Please go back and try again.",
+            "wrong fee refusal: " + JSON.stringify(after.feeBoundError),
+        );
+        assert(
+            after.passwordTop === before.passwordTop,
+            "the password field moved " +
+                (after.passwordTop - before.passwordTop) +
+                "px when the send was refused",
+        );
+        assert(
+            after.sendTop === before.sendTop,
+            "Sign & Send moved " +
+                (after.sendTop - before.sendTop) +
+                "px when the send was refused",
+        );
+    } finally {
+        env.routeOpts.baseFeeWei = undefined;
+        await backToAddress(env.page);
+    }
+});
+
+// --------- a send from an address the selected wallet does not hold (#609)
+//
+// The selection is saved apart from the confirmation screen, so the popup can
+// reopen onto the screen with a wallet selected that does not hold its From
+// address, and Sign & Send then refuses the send. Another popup selecting the
+// key wallet would save that selection; here it is written into storage, and
+// the popup reopened.
+
+test("a send from an address the selected wallet does not hold leaves the password field and Sign & Send where they were (#609)", async (env) => {
+    try {
+        // From the HD wallet's address.
+        await goToConfirm(env.page, {
+            token: "ETH",
+            balance: FUNDED_ETH_TEXT + " ETH",
+            amount: COMFORTABLE_AMOUNT,
+        });
+        // The screen's own save lands first, so it cannot write over the
+        // selection below.
+        await waitForPersisted(
+            env.page,
+            "currentView",
+            "confirm-tx",
+            "before selecting the key wallet",
+        );
+        await env.page.evaluate(
+            () =>
+                new Promise((resolve) => {
+                    chrome.storage.local.get("autistmask", (r) => {
+                        const record = {
+                            ...r.autistmask,
+                            selectedWallet: 1,
+                            selectedAddress: 0,
+                        };
+                        chrome.storage.local.set(
+                            { autistmask: record },
+                            resolve,
+                        );
+                    });
+                }),
+        );
+        await reopenPopup(env, "confirm-tx");
+        await waitForEstimate(env.page);
+        // The refusal shown anywhere on the screen, not only in its own box:
+        // shown on the password error line instead, the test fails on the
+        // moves checked below rather than on the wait for it.
+        const refusal = env.page
+            .locator("#view-confirm-tx")
+            .getByText("does not hold the From address above")
+            .filter({ visible: true });
+        const before = await confirmState(env.page);
+        assert(
+            !before.sendDisabled && (await refusal.count()) === 0,
+            "the screen is not ready to send: " + JSON.stringify(before),
+        );
+
+        const sent = env.routeOpts.broadcastTransactions.length;
+        await fillPasswordAndSend(env.page);
+        await refusal.waitFor({ timeout: 60000 });
+        const after = await confirmState(env.page);
+
+        // Printed pass or fail, as the dust threshold test does.
+        console.log(
+            "# refused From address: password field top " +
+                before.passwordTop +
+                " -> " +
+                after.passwordTop +
+                "px, Sign & Send top " +
+                before.sendTop +
+                " -> " +
+                after.sendTop +
+                "px",
+        );
+        assert(
+            env.routeOpts.broadcastTransactions.length === sent,
+            "a send from an address the selected wallet does not hold" +
+                " reached the RPC",
+        );
+        assert(
+            after.passwordTop === before.passwordTop,
+            "the password field moved " +
+                (after.passwordTop - before.passwordTop) +
+                "px when the send was refused",
+        );
+        assert(
+            after.sendTop === before.sendTop,
+            "Sign & Send moved " +
+                (after.sendTop - before.sendTop) +
+                "px when the send was refused",
+        );
+        // Only now, where the refusal is shown. Its sentence is wrapped across
+        // lines in index.html.
+        const shownIn = await refusal.evaluate((el) => ({
+            id: el.id,
+            text: el.textContent.replace(/\s+/g, " ").trim(),
+        }));
+        assert(
+            shownIn.id === "confirm-from-address-error" &&
+                shownIn.text ===
+                    "The selected wallet does not hold the From address above," +
+                        " so nothing was sent. Please go back and send again.",
+            "wrong From address refusal: " + JSON.stringify(shownIn),
+        );
+    } finally {
+        // A reopened popup restores no Send screen beneath this one, so Back
+        // lands on the selected address. Then Home, and the HD wallet's
+        // address, which the later tests send from.
+        if (await env.page.isVisible("#view-confirm-tx")) {
+            await env.page.click("#btn-confirm-back");
+        }
+        if (await env.page.isVisible("#view-send")) {
+            await env.page.click("#btn-send-back");
+        }
+        await visible(env.page, "#view-address");
+        await env.page.click("#btn-address-back");
+        await visible(env.page, "#view-main");
+        await openAddressDetail(env.page);
+    }
+});
+
 // ------------------------------ the wait for a receipt ending in error (#315)
 //
 // README.md (WaitTx) documents two ways the wait ends on the error screen: a
@@ -3113,10 +3436,14 @@ test("six failed receipt lookups in a row end on the unreachable-network message
 // timeout ("<iframe id=\"pwn\"> intercepts pointer events") rather than as
 // anything that names the defect.
 
-// Verbatim from the issue's reproduction.
+// The issue's reproduction, with the frame sized to the popup.
 const HOSTILE_SYMBOL =
     '<iframe id="pwn" src="https://dapp.e2e.test/" ' +
-    'style="position:fixed;left:0;top:0;width:360px;height:600px;z-index:99999"></iframe>';
+    'style="position:fixed;left:0;top:0;width:' +
+    POPUP_VIEWPORT.width +
+    "px;height:" +
+    POPUP_VIEWPORT.height +
+    'px;z-index:99999"></iframe>';
 
 // What a correctly escaped and capped render of it reads as: the first
 // MAX_SYMBOL_LENGTH-1 characters and an ellipsis. Spelled out rather than
@@ -4708,8 +5035,20 @@ function addressRowReport(page) {
     });
 }
 
+// Measured at the popup's 396x600 (POPUP_VIEWPORT). Every page in this
+// context, approval windows included, is otherwise 1280x720 whatever size
+// the extension asks for, and a page that wide never scrolls sideways. The
+// page is then put back to the size it had, so the size a later step runs at
+// does not depend on whether this one ran.
 async function assertAddressesFit(page, where) {
-    const report = await addressRowReport(page);
+    const sizeBefore = page.viewportSize();
+    await page.setViewportSize(POPUP_VIEWPORT);
+    let report;
+    try {
+        report = await addressRowReport(page);
+    } finally {
+        await page.setViewportSize(sizeBefore);
+    }
     assert(
         report.rows.length > 0,
         where + ": no address rows were rendered, so nothing was measured",
@@ -4869,6 +5208,9 @@ async function main() {
         seedTokenBalance: false,
         ethBalanceWei: null,
         failGasEstimate: false,
+        // Whether a JSON-RPC batch asking for a balance is held unanswered:
+        // the confirmation screen's own balance read (#558).
+        holdBalance: false,
         holdGasEstimate: false,
         // Whether a JSON-RPC batch asking for a transaction count is held
         // unanswered: the address scan after creating a wallet (#475).

tests/fabricatedDecimals.test.js

@@ -136,7 +136,7 @@ function erc20AmountLine(data, tokenAddress) {
 }
 
 function swapAmountLine(data) {
-    return decodeCalldata(data, ROUTER).details.find(
+    return decodeCalldata(data, ROUTER, "0x1").details.find(
         (d) => d.label === "Amount",
     ).value;
 }

tests/firstWalletRefresh.test.js

@@ -0,0 +1,135 @@
+// A popup that opened with no wallet never started the ten-second refresh, so
+// after the first wallet was added Home went on showing the balance it had then
+// until the popup was reopened
+// (https://git.eeqj.de/sneak/AutistMask/issues/530). Each test boots the real
+// popup, adds wallets through AddWallet, and runs the intervals the popup set
+// with tick(). The balance stand-in writes what the chain holds onto every
+// address, as the real refreshBalances() does.
+
+const { HDNodeWallet, Mnemonic } = require("ethers");
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+    ADDRESS,
+} = require("./support/popupBoot");
+
+const PHRASE =
+    "abandon abandon abandon abandon abandon abandon " +
+    "abandon abandon abandon abandon abandon about";
+const PRIVATE_KEY = "0x" + "11".repeat(32);
+const XPRV = HDNodeWallet.fromSeed(
+    Mnemonic.fromPhrase(PHRASE).computeSeed(),
+).extendedKey;
+const PASSWORD = "correct horse battery staple";
+
+const TABS = [
+    { tab: "tab-mnemonic", field: "wallet-mnemonic", secret: PHRASE },
+    { tab: "tab-privkey", field: "import-private-key", secret: PRIVATE_KEY },
+    { tab: "tab-xprv", field: "import-xprv-key", secret: XPRV },
+];
+
+// A record this build cannot read: its wallets are a string.
+const UNREADABLE = {
+    hasWallet: true,
+    wallets: ADDRESS,
+    activeAddress: ADDRESS,
+};
+
+// The ETH balance the chain holds for every address, in ether.
+let chainBalance = "0.0";
+
+// Boots the popup over `stored`, with the balance stand-in reading the chain.
+async function boot(stored) {
+    const page = await bootPopup(stored);
+    const { refreshBalances } = require("../src/shared/balances");
+    refreshBalances.mockImplementation(async (wallets) => {
+        for (const wallet of wallets) {
+            for (const addr of wallet.addresses) addr.balance = chainBalance;
+        }
+    });
+    return { page, refreshBalances };
+}
+
+// Fills in the open AddWallet screen and presses "Import".
+async function importOn(page, { tab, field, secret }) {
+    await page.click(tab);
+    page.node(field).value = secret;
+    page.node("add-wallet-password").value = PASSWORD;
+    page.node("add-wallet-password-confirm").value = PASSWORD;
+    await page.click("btn-add-wallet-confirm");
+}
+
+beforeEach(() => {
+    chainBalance = "0.0";
+});
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+describe("a popup that opened on Welcome", () => {
+    test.each(TABS)(
+        "after the first wallet is added from $tab, funds that arrive show on Home",
+        async (entry) => {
+            const { page } = await boot(undefined);
+            expect(page.pageErrors).toEqual([]);
+            await page.click("btn-welcome-add");
+            await importOn(page, entry);
+            expect(page.visibleViews()).toEqual(["main"]);
+            expect(page.text("total-value")).toBe("0.0000 ETH");
+
+            chainBalance = "2.0";
+            await page.tick();
+
+            expect(page.text("total-value")).toBe("2.0000 ETH");
+        },
+    );
+
+    test("a second wallet starts no second refresh", async () => {
+        const { page, refreshBalances } = await boot(undefined);
+        await page.click("btn-welcome-add");
+        await importOn(page, TABS[1]);
+        await page.click("btn-add-wallet-bottom");
+        await importOn(page, TABS[0]);
+        const calls = refreshBalances.mock.calls.length;
+
+        await page.tick();
+
+        expect(refreshBalances).toHaveBeenCalledTimes(calls + 1);
+    });
+
+    test("a wallet added as the recovery screen goes up starts no refresh", async () => {
+        const { page, refreshBalances } = await boot(undefined);
+        // The stored record becomes unreadable during the address scan that
+        // follows the import, and a save finds it.
+        const { scanForAddresses } = require("../src/shared/balances");
+        const { saveState } = require("../src/shared/state");
+        scanForAddresses.mockImplementationOnce(async () => {
+            page.storage.write("autistmask", UNREADABLE);
+            await saveState().catch(() => {});
+            return { addresses: [], nextIndex: 1 };
+        });
+        await page.click("btn-welcome-add");
+        await importOn(page, TABS[0]);
+        expect(page.visibleViews()).toEqual(["state-recovery"]);
+
+        await page.tick();
+
+        expect(refreshBalances).not.toHaveBeenCalled();
+    });
+});
+
+describe("a popup that opened with a wallet", () => {
+    test("adding a wallet starts no second refresh", async () => {
+        const { page, refreshBalances } = await boot(unversionedValidProfile());
+        await page.click("btn-add-wallet-bottom");
+        await importOn(page, TABS[1]);
+        const calls = refreshBalances.mock.calls.length;
+
+        await page.tick();
+
+        expect(refreshBalances).toHaveBeenCalledTimes(calls + 1);
+    });
+});

tests/flashLine.test.js

@@ -80,6 +80,7 @@ describe.each([
         jest.doMock("../src/shared/state", () => ({
             state: { trackedTokens: [] },
             saveState,
+            currentNetwork: () => ({ chainId: 1 }),
         }));
         jest.doMock("../src/popup/views/helpers", () => ({
             $: element,

tests/nativeCurrency.test.js

@@ -151,7 +151,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const { state } = require("../src/shared/state");
 const { NETWORKS } = require("../src/shared/networks");
@@ -245,7 +245,7 @@ describe.each([
     test("the value", async () => {
         await confirmSend("0.1");
         expect(text("confirm-type")).toBe("Native " + symbol + " transfer");
-        expect(text("confirm-amount")).toBe("0.1 " + symbol);
+        expect(text("confirm-amount")).toBe("0.1000 " + symbol);
         await approveTx(NETWORKS[networkId].chainId);
         expect(text("approve-tx-value")).toBe("0.0100 " + symbol);
     });
@@ -271,6 +271,13 @@ describe.each([
         );
     });
 
+    test("the warning for a recipient that has never sent a transaction", async () => {
+        await confirmSend("0.1");
+        expect(text("confirm-recipient-warning")).toContain(
+            "has never sent a transaction and holds no " + symbol + ".",
+        );
+    });
+
     // A token reports whatever symbol it likes. One reporting the label the
     // wallet shows its native token under, on this network or any other, is
     // a fake, exactly as one reporting `ETH` always was.
@@ -336,14 +343,11 @@ describe.each([
 
     test("the insufficient-balance error", async () => {
         await confirmSend("2");
-        expect(
-            global.document.getElementById("confirm-errors").innerHTML,
-        ).toContain(
-            "You have 1.5000 " +
+        expect(text("confirm-balance-error")).toBe(
+            "Your " +
                 symbol +
-                " but are trying to send 2 " +
-                symbol +
-                ".",
+                " balance does not cover this amount. Please go back and send" +
+                " a smaller amount.",
         );
     });
 });
@@ -425,10 +429,10 @@ describe.each([
             await global.document
                 .getElementById("btn-confirm-send")
                 .handlers.get("click")();
-            expect(text("wait-tx-summary")).toBe("0.1 " + symbol);
+            expect(text("wait-tx-summary")).toBe("0.1000 " + symbol);
             state.networkId = activeNetworkId;
             txStatus.restoreWait();
-            expect(text("wait-tx-summary")).toBe("0.1 " + symbol);
+            expect(text("wait-tx-summary")).toBe("0.1000 " + symbol);
         });
 
         test("the transaction detail screen's type line and fee", async () => {

tests/persistedFieldContract.test.js

@@ -97,6 +97,7 @@ const {
     normalizePersisted,
 } = require("../src/shared/persistedState");
 const { stateProblem } = require("../src/shared/stateSchema");
+const { isKnownNetworkId } = require("../src/shared/networks");
 const { RESTORABLE_VIEWS } = require("../src/shared/restorableViews");
 const {
     bootPopup,
@@ -193,6 +194,29 @@ const CONTRACT = [
         floorOnly: [[1, 2], [null], [{}], [[TOKEN_ADDRESS]]],
         holds: (v) => everyEntry(v, (t) => isRecord(t) && isText(t.address)),
     },
+    {
+        field: "networkTrackedTokens",
+        kind: KIND.ENTRIES,
+        hostile: [42, "notarecord", { sepolia: "notalist" }],
+        floorOnly: [
+            [1, 2],
+            { sepolia: [1, 2] },
+            { mainnet: [null, {}, [TOKEN_ADDRESS]] },
+            { notanetwork: [{ address: TOKEN_ADDRESS }] },
+            JSON.parse('{"__proto__":[{"address":"0xabc"}]}'),
+        ],
+        // Each list is put straight back onto trackedTokens by
+        // applyChainSwitchFields() when its network becomes the active one, so
+        // it is floored the same way; a key that names no network is dropped.
+        holds: (v) =>
+            isRecord(v) &&
+            Object.getPrototypeOf(v) === Object.prototype &&
+            Object.keys(v).every(
+                (id) =>
+                    isKnownNetworkId(id) &&
+                    everyEntry(v[id], (t) => isRecord(t) && isText(t.address)),
+            ),
+    },
     {
         field: "allowedSites",
         kind: KIND.ENTRIES,
@@ -417,6 +441,17 @@ const CONTRACT = [
                 views: ["error-tx"],
                 restored: false,
             },
+            // A chain id naming no network has no explorer to link to.
+            {
+                value: { hash: "0x1", to: ADDRESS, chainId: "0x5" },
+                views: ["success-tx"],
+                restored: false,
+            },
+            {
+                value: { message: "boom", to: ADDRESS, chainId: "0x5" },
+                views: ["error-tx"],
+                restored: false,
+            },
             // transaction passes on `data.tx`.
             {
                 value: { tx: { hash: "0x1" } },
@@ -430,6 +465,26 @@ const CONTRACT = [
                         from: ADDRESS,
                         to: ADDRESS,
                         contractAddress: 42,
+                        chainId: "0x1",
+                    },
+                },
+                views: ["transaction"],
+                restored: false,
+            },
+            // A transaction whose chain id is missing or names no network has
+            // no explorer to link to and no Blockscout to be read from.
+            {
+                value: { tx: { hash: "0x1", from: ADDRESS, to: ADDRESS } },
+                views: ["transaction"],
+                restored: false,
+            },
+            {
+                value: {
+                    tx: {
+                        hash: "0x1",
+                        from: ADDRESS,
+                        to: ADDRESS,
+                        chainId: "0x5",
                     },
                 },
                 views: ["transaction"],
@@ -453,6 +508,33 @@ const CONTRACT = [
                 views: ["confirm-tx"],
                 restored: false,
             },
+            // The amount line splits the amount to cut it to four decimals.
+            {
+                value: {
+                    pendingTx: {
+                        token: "ETH",
+                        from: ADDRESS,
+                        to: ADDRESS,
+                        amount: 42,
+                    },
+                },
+                views: ["confirm-tx"],
+                restored: false,
+            },
+            // A chain id naming no network has no explorer to link to.
+            {
+                value: {
+                    pendingTx: {
+                        token: "ETH",
+                        from: ADDRESS,
+                        to: ADDRESS,
+                        amount: "1",
+                        chainId: "0x5",
+                    },
+                },
+                views: ["confirm-tx"],
+                restored: false,
+            },
             // wait-tx passes on `pendingWait.hash`; restoreWait() has checked
             // the fields below it since it was written, and this is the
             // regression guard.
@@ -761,7 +843,13 @@ const WELL_FORMED_DATA = {
     message: "boom",
     to: ADDRESS,
     decoded: { details: [{ address: TOKEN_ADDRESS }] },
-    tx: { hash: "0x1", from: ADDRESS, to: ADDRESS, contractAddress: null },
+    tx: {
+        hash: "0x1",
+        from: ADDRESS,
+        to: ADDRESS,
+        contractAddress: null,
+        chainId: "0x1",
+    },
     pendingTx: {
         token: "ETH",
         from: ADDRESS,
@@ -770,7 +858,7 @@ const WELL_FORMED_DATA = {
     },
     pendingWait: {
         hash: "0x1",
-        txInfo: { to: ADDRESS, amount: "1" },
+        txInfo: { to: ADDRESS, amount: "1", chainId: "0x1" },
         broadcastTime: BROADCAST_TIME,
     },
 };

tests/popupBoot.test.js

@@ -0,0 +1,87 @@
+// A timer the popup started and that fires after cleanupPopup() has removed
+// the page throws "document is not defined", and the throw fails whatever test
+// the jest worker is running by then, in this file or another
+// (https://git.eeqj.de/sneak/AutistMask/issues/578). The flash message's
+// timer is the one that did it. A throw from a timer during a test fails that
+// test, so each test here passes only if nothing throws.
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+    ADDRESS,
+} = require("./support/popupBoot");
+
+const FLASH_MS = 10;
+
+function wait(ms) {
+    return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+test("a flash message clears while the page is up", async () => {
+    const page = await bootPopup(unversionedValidProfile());
+    const { showFlash } = require("../src/popup/views/helpers");
+    showFlash("Copied.", FLASH_MS);
+    expect(page.text("flash-msg")).toBe("Copied.");
+
+    await wait(FLASH_MS * 5);
+
+    expect(page.text("flash-msg")).toBe("");
+});
+
+test("a flash message's timer does not fire after cleanupPopup()", async () => {
+    await bootPopup(unversionedValidProfile());
+    const { showFlash } = require("../src/popup/views/helpers");
+    showFlash("Copied.", FLASH_MS);
+    cleanupPopup();
+
+    await wait(FLASH_MS * 5);
+});
+
+// A boot onto a screen that sends a request no mocked module answers: that
+// request reaches the boot's fetch() stub, never the internet
+// (https://git.eeqj.de/sneak/AutistMask/issues/559).
+function restoringOnto(view, viewData) {
+    return unversionedValidProfile({
+        currentView: view,
+        selectedWallet: 0,
+        selectedAddress: 0,
+        viewStack: ["main"],
+        viewData,
+    });
+}
+
+test("the transaction screen's Blockscout request reaches the stub", async () => {
+    const page = await bootPopup(
+        restoringOnto("transaction", {
+            tx: { hash: "0x1", from: ADDRESS, to: ADDRESS, chainId: "0x1" },
+        }),
+    );
+
+    expect(page.visibleViews()).toEqual(["transaction"]);
+    expect(globalThis.fetch.mock.calls.map((call) => call[0])).toEqual([
+        "https://eth.blockscout.com/api/v2/transactions/0x1",
+    ]);
+});
+
+test("the confirmation screen's Etherscan lookup reaches the stub", async () => {
+    const page = await bootPopup(
+        restoringOnto("confirm-tx", {
+            pendingTx: {
+                token: "ETH",
+                from: ADDRESS,
+                to: ADDRESS,
+                amount: "1",
+            },
+        }),
+    );
+
+    expect(page.visibleViews()).toEqual(["confirm-tx"]);
+    expect(globalThis.fetch.mock.calls.map((call) => call[0])).toEqual([
+        "https://etherscan.io/address/" + ADDRESS,
+    ]);
+});

tests/rpcErrorLog.test.js

@@ -74,7 +74,7 @@ test("ethers puts the URL in the error message, not in the short message", async
 test("the recipient checks before a send", async () => {
     await getFullWarnings(ADDRESS, getProvider(RPC_URL, "mainnet"));
     expectFailureLoggedWithoutKey("contract check failed");
-    expectFailureLoggedWithoutKey("tx count check failed");
+    expectFailureLoggedWithoutKey("tx count or balance check failed");
 });
 
 test("the ENS reverse lookup", async () => {

tests/sendAmountRule.test.js

@@ -97,7 +97,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const { state } = require("../src/shared/state");
 const send = require("../src/popup/views/send");

tests/sendDisplayFloor.test.js

@@ -151,7 +151,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const { refreshBalances } = require("../src/shared/balances");
 const { state } = require("../src/shared/state");
@@ -203,6 +203,12 @@ function errors() {
     return global.document.getElementById("confirm-errors").innerHTML;
 }
 
+// The message for an amount the balance does not cover, while it is shown.
+function balanceError() {
+    const box = global.document.getElementById("confirm-balance-error");
+    return box.style.visibility === "visible" ? box.textContent : "";
+}
+
 // The ETH balance the node reports and the token rows the explorer reports,
 // fetched and stored exactly where the popup stores them. The node reports the
 // token holding the explorer does.
@@ -311,9 +317,10 @@ describe("a tracked token holding below 0.000001 never renders as zero", () => {
         await confirmSend("0.0000005", TOKEN);
         expect(text("confirm-balance")).toBe("0.0000005 TOK");
         expect(errors()).toBe("");
+        expect(balanceError()).toBe("");
         await confirmSend("0.0000006", TOKEN);
-        expect(errors()).toContain(
-            "You have 0.0000005 TOK but are trying to send 0.0000006 TOK.",
+        expect(balanceError()).toContain(
+            "Your TOK balance does not cover this amount.",
         );
     });
 
@@ -327,6 +334,7 @@ describe("a tracked token holding below 0.000001 never renders as zero", () => {
         await confirmSend("1.5", TOKEN);
         expect(text("confirm-balance")).toBe("1.5000 TOK");
         expect(errors()).toBe("");
+        expect(balanceError()).toBe("");
     });
 
     test("with more than 18 decimals and a holding below 10^-18", async () => {
@@ -340,9 +348,8 @@ describe("a tracked token holding below 0.000001 never renders as zero", () => {
         );
         await confirmSend("0.000000000000000001", TOKEN);
         expect(text("confirm-balance")).toBe("0.000000000000000000000001 TOK");
-        expect(errors()).toContain(
-            "You have 0.000000000000000000000001 TOK but are trying to send" +
-                " 0.000000000000000001 TOK.",
+        expect(balanceError()).toContain(
+            "Your TOK balance does not cover this amount.",
         );
     });
 });
@@ -367,9 +374,10 @@ describe("an untracked token holding below 0.000001 never renders as zero", () =
         await confirmSend("0.0000005", TOKEN);
         expect(text("confirm-balance")).toBe("0.0000005 TOK");
         expect(errors()).toBe("");
+        expect(balanceError()).toBe("");
         await confirmSend("0.0000006", TOKEN);
-        expect(errors()).toContain(
-            "You have 0.0000005 TOK but are trying to send 0.0000006 TOK.",
+        expect(balanceError()).toContain(
+            "Your TOK balance does not cover this amount.",
         );
     });
 });

tests/sendMax.test.js

@@ -146,7 +146,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const { Transaction, Wallet, formatEther } = require("ethers");
 const { refreshBalances } = require("../src/shared/balances");
@@ -306,7 +306,8 @@ describe("Max on an ETH send", () => {
         openSend();
         await pressMax();
         await review();
-        expect(text("confirm-amount")).toBe(maxAfter(20n * GWEI) + " ETH");
+        expect(confirmed.amount).toBe(maxAfter(20n * GWEI));
+        expect(text("confirm-amount")).toBe("1.2341 ETH");
         expect(el("confirm-errors").innerHTML).toBe("");
         expect(el("confirm-amount-fee-error").style.visibility).toBe("hidden");
         expect(canSend()).toBe(true);
@@ -322,14 +323,16 @@ describe("Max on an ETH send", () => {
         // Kept, the Send screen's amount would be refused for want of funds.
         mockNode.feeData = fees(30n * GWEI);
         await review();
-        expect(text("confirm-amount")).toBe(maxAfter(30n * GWEI) + " ETH");
+        expect(confirmed.amount).toBe(maxAfter(30n * GWEI));
+        expect(text("confirm-amount")).toBe("1.2339 ETH");
         expect(canSend()).toBe(true);
 
         // And falls when the screen is shown again, as on reopening the popup.
         mockNode.feeData = fees(10n * GWEI);
         confirmTx.restore();
         await settle();
-        expect(text("confirm-amount")).toBe(maxAfter(10n * GWEI) + " ETH");
+        expect(confirmed.amount).toBe(maxAfter(10n * GWEI));
+        expect(text("confirm-amount")).toBe("1.2343 ETH");
         expect(canSend()).toBe(true);
     });
 
@@ -526,7 +529,8 @@ describe("Max on an ETH send", () => {
         el("send-amount").handlers.get("input")();
         mockNode.feeData = fees(30n * GWEI);
         await review();
-        expect(text("confirm-amount")).toBe("0.5 ETH");
+        expect(confirmed.amount).toBe("0.5");
+        expect(text("confirm-amount")).toBe("0.5000 ETH");
     });
 });
 
@@ -540,7 +544,8 @@ describe("Max on a token send", () => {
         await pressMax();
         expect(el("send-amount").value).toBe("1234.567890123456789012");
         await review();
-        expect(text("confirm-amount")).toBe("1234.567890123456789012 TOK");
+        expect(confirmed.amount).toBe("1234.567890123456789012");
+        expect(text("confirm-amount")).toBe("1234.5678 TOK");
         expect(canSend()).toBe(true);
     });
 
@@ -553,7 +558,8 @@ describe("Max on a token send", () => {
         await pressMax();
         expect(el("send-amount").value).toBe("1234.567890123456789012");
         await review();
-        expect(text("confirm-amount")).toBe("1234.567890123456789012 TOK");
+        expect(confirmed.amount).toBe("1234.567890123456789012");
+        expect(text("confirm-amount")).toBe("1234.5678 TOK");
         expect(canSend()).toBe(true);
     });
 

tests/stateRecovery.test.js

@@ -225,7 +225,12 @@ describe("a popup already open when the stored profile becomes unreadable", () =
                 viewData: {
                     pendingWait: {
                         hash: "0x1",
-                        txInfo: { to: ADDRESS, amount: "1", token: "ETH" },
+                        txInfo: {
+                            to: ADDRESS,
+                            amount: "1",
+                            token: "ETH",
+                            chainId: "0x1",
+                        },
                         broadcastTime: Date.now(),
                     },
                 },

tests/stateWriteLock.test.js

@@ -0,0 +1,95 @@
+// A popup save reads the stored record, merges this page's changes into it
+// and writes it back. The background's write of a network the user approved
+// used to be able to land between that read and that write, and the popup's
+// write then put the old network back
+// (https://git.eeqj.de/sneak/AutistMask/issues/641). Every write of the record
+// now holds one lock from its read to its write.
+//
+// The popup and the background run here as the real modules over one shared
+// storage stub, and share the lock the way the extension's pages and its
+// background share the browser's (tests/support/navigatorLocks.js).
+
+const { makeStorageStub } = require("./support/storageStub");
+
+function loadContexts(storage) {
+    jest.resetModules();
+    globalThis.chrome = { storage: { local: storage.local } };
+    return {
+        popup: require("../src/shared/state"),
+        background: require("../src/background/state"),
+        applyChainSwitchFields: require("../src/shared/chainSwitchFields")
+            .applyChainSwitchFields,
+    };
+}
+
+// Lets every pending promise callback run, and then some.
+function nextMacrotask() {
+    return new Promise((resolve) => setImmediate(resolve));
+}
+
+afterEach(() => {
+    delete globalThis.chrome;
+    jest.restoreAllMocks();
+});
+
+test("a network the background switches to during a popup save stays stored", async () => {
+    const storage = makeStorageStub({ autistmask: { networkId: "sepolia" } });
+    const { popup, background, applyChainSwitchFields } = loadContexts(storage);
+    await popup.loadState();
+
+    // The popup navigates, so its save has a change of its own to write.
+    popup.state.currentView = "settings";
+
+    // The popup's save has read the record and is about to write it back when
+    // the user's approval of a site's switch to mainnet reaches the
+    // background. Without the lock the background's whole update runs before
+    // the next macrotask; with it, the update waits for the popup's write.
+    let backgroundSwitch;
+    const realSet = storage.local.set.getMockImplementation();
+    storage.local.set.mockImplementationOnce(async (items) => {
+        backgroundSwitch = background.updateState((fresh) =>
+            applyChainSwitchFields(fresh, "mainnet"),
+        );
+        await nextMacrotask();
+        return realSet(items);
+    });
+
+    await popup.saveState();
+    await backgroundSwitch;
+
+    const stored = storage.read("autistmask");
+    expect(stored.networkId).toBe("mainnet");
+    expect(stored.currentView).toBe("settings");
+});
+
+test("after a save that failed, the next save still keeps a network the background switches to during it", async () => {
+    jest.spyOn(console, "error").mockImplementation(() => {});
+    const storage = makeStorageStub({ autistmask: { networkId: "sepolia" } });
+    const { popup, background, applyChainSwitchFields } = loadContexts(storage);
+    await popup.loadState();
+    popup.state.currentView = "settings";
+
+    // The first save's write is refused, so it gives the lock back having
+    // failed.
+    storage.local.set.mockRejectedValueOnce(new Error("quota exceeded"));
+    await expect(popup.saveState()).rejects.toThrow("quota exceeded");
+
+    // The next save is between its read and its write when the background
+    // switches to mainnet, as in the test above.
+    let backgroundSwitch;
+    const realSet = storage.local.set.getMockImplementation();
+    storage.local.set.mockImplementationOnce(async (items) => {
+        backgroundSwitch = background.updateState((fresh) =>
+            applyChainSwitchFields(fresh, "mainnet"),
+        );
+        await nextMacrotask();
+        return realSet(items);
+    });
+
+    await popup.saveState();
+    await backgroundSwitch;
+
+    const stored = storage.read("autistmask");
+    expect(stored.networkId).toBe("mainnet");
+    expect(stored.currentView).toBe("settings");
+});

tests/support/navigatorLocks.js

@@ -0,0 +1,26 @@
+// `navigator.locks` for the unit tests, which run on node, where there is none.
+//
+// One lock per name: granted in the order it was asked for, and let go when
+// the callback settles, whether it resolved or rejected. That is what the
+// browser's own does for the one call the extension makes,
+// `navigator.locks.request(name, callback)`. Every module a test file loads
+// shares it, as every page of the extension and its background share the
+// browser's.
+//
+// Run before each test file by `setupFiles` in package.json.
+
+// For each name, a promise that settles once the last request for it has
+// let the lock go.
+const released = new Map();
+
+function request(name, callback) {
+    const previous = released.get(name) || Promise.resolve();
+    const result = previous.then(() => callback({ name, mode: "exclusive" }));
+    released.set(
+        name,
+        result.catch(() => {}),
+    );
+    return result;
+}
+
+globalThis.navigator = { locks: { request } };

tests/support/popupBoot.js

@@ -43,6 +43,13 @@ jest.doMock("ethereum-blockies-base64", () => makeBlockie);
 // Taken before any boot replaces them; see bootPopup().
 const realSetInterval = globalThis.setInterval;
 const realClearInterval = globalThis.clearInterval;
+const realSetTimeout = globalThis.setTimeout;
+const realClearTimeout = globalThis.clearTimeout;
+const realFetch = globalThis.fetch;
+
+// Every timeout set since the last cleanupPopup() that has neither fired nor
+// been cleared. cleanupPopup() clears them all.
+const pendingTimeouts = new Set();
 
 const POPUP_HTML = fs.readFileSync(
     path.join(__dirname, "..", "..", "src", "popup", "index.html"),
@@ -254,8 +261,14 @@ async function settle() {
 async function bootPopup(stored, options) {
     jest.resetModules();
 
-    // The three modules that reach the network. None is on the path under
-    // test; all would make the suite hit the internet.
+    // The RPC requests made through src/shared/balances.js go through Node's
+    // own http and https modules, not fetch(), so the fetch() stub below would
+    // not stop them, which is why that module stays mocked.
+    // src/shared/prices.js and src/shared/transactions.js send their requests
+    // through fetch(), and their mocks answer with no prices and no
+    // transactions. Every request the page still sends, such as the
+    // transaction screen's Blockscout lookup and the Etherscan lookup in
+    // src/shared/etherscanLabels.js, meets the fetch() stub.
     jest.doMock("../../src/shared/prices", () => ({
         prices: {},
         refreshPrices: jest.fn(async () => {}),
@@ -328,6 +341,12 @@ async function bootPopup(stored, options) {
             windowListeners[name].push(fn);
         },
     };
+    // Every fetch() the page makes fails, as it does elsewhere in the suite,
+    // instead of reaching the internet. A new stub per boot, so the calls it
+    // records start with that boot. Put back by cleanupPopup().
+    globalThis.fetch = jest.fn(() => {
+        throw new Error("tests must not perform network requests");
+    });
     // The ten-second refresh init() starts, and a transaction wait's timers,
     // would outlive the test. So every interval is recorded rather than
     // started, clearInterval() removes it as a browser would, and tick() below
@@ -342,6 +361,24 @@ async function bootPopup(stored, options) {
     globalThis.clearInterval = (id) => {
         intervals.delete(id);
     };
+    // Timeouts, such as the one that clears a flash message, run for real, but
+    // each is recorded until it fires or is cleared, so cleanupPopup() can
+    // clear the ones still pending. One that fired after the page was removed
+    // would throw "document is not defined" into whatever test the worker runs
+    // by then. jest.useFakeTimers() in a test does not reach them. Put back by
+    // cleanupPopup().
+    globalThis.setTimeout = (fn, ms, ...args) => {
+        const timer = realSetTimeout(() => {
+            pendingTimeouts.delete(timer);
+            fn(...args);
+        }, ms);
+        pendingTimeouts.add(timer);
+        return timer;
+    };
+    globalThis.clearTimeout = (timer) => {
+        pendingTimeouts.delete(timer);
+        realClearTimeout(timer);
+    };
 
     require("../../src/popup/index");
 
@@ -407,6 +444,11 @@ function cleanupPopup() {
     delete globalThis.window;
     globalThis.setInterval = realSetInterval;
     globalThis.clearInterval = realClearInterval;
+    for (const timer of pendingTimeouts) realClearTimeout(timer);
+    pendingTimeouts.clear();
+    globalThis.setTimeout = realSetTimeout;
+    globalThis.clearTimeout = realClearTimeout;
+    globalThis.fetch = realFetch;
 }
 
 module.exports = {

tests/tokenTransferDetail.test.js

@@ -8,6 +8,14 @@
 // tracks. It decodes against the address the explorer reports the transaction
 // was sent to.
 //
+// Its links open the explorer of the network the transaction was sent on,
+// whichever network is active
+// (https://git.eeqj.de/sneak/AutistMask/issues/584), and the transaction is
+// read from that network's Blockscout, the one Settings has for it
+// (https://git.eeqj.de/sneak/AutistMask/issues/623). Its decoded details name
+// the token, and scale its amount, from what the wallet knows of that
+// network's tokens (https://git.eeqj.de/sneak/AutistMask/issues/629).
+//
 // The row is the one the real history parser makes from the explorer's answer,
 // opened through transactionDetail.show(), which is what a click on the row
 // calls. Driven against a minimal DOM stub in the shape
@@ -22,10 +30,10 @@ jest.mock("../src/shared/log", () => ({
         warnf: () => {},
         errorf: () => {},
     },
-    debugFetch: async (url) => ({
-        ok: true,
-        json: async () => mockExplorerAnswer(url),
-    }),
+    debugFetch: async (url) => {
+        mockAsked.push(url);
+        return { ok: true, json: async () => mockExplorerAnswer(url) };
+    },
     setRuntimeDebug: () => {},
     isDebug: () => false,
 }));
@@ -35,10 +43,13 @@ globalThis.chrome = {
 };
 
 const { state } = require("../src/shared/state");
+const { NETWORKS } = require("../src/shared/networks");
 const { fetchRecentTransactions } = require("../src/shared/transactions");
 const transactionDetail = require("../src/popup/views/transactionDetail");
 
 const EXPLORER = "https://explorer.example/api/v2";
+// A Blockscout that knows nothing of the transaction.
+const OTHER_EXPLORER = "https://other-explorer.example/api/v2";
 const HOLDER = "0x0000000000000000000000000000000000000a11";
 const RECIPIENT = "0x711e691962E5c054b78071C789A0C8CE657377aD";
 // A token the wallet tracks and the bundled token list does not name.
@@ -51,6 +62,9 @@ const TRANSFER_DATA = new Interface([
     "function transfer(address to, uint256 amount)",
 ]).encodeFunctionData("transfer", [RECIPIENT, 1234500000n]);
 
+// Every URL asked of a Blockscout, in order.
+const mockAsked = [];
+
 // The explorer's answers: the transfer in HOLDER's token transfers, and the
 // transaction itself, sent to the token contract.
 function mockExplorerAnswer(url) {
@@ -77,7 +91,11 @@ function mockExplorerAnswer(url) {
         };
     }
     if (url === EXPLORER + "/transactions/" + TX_HASH) {
-        return { to: { hash: TOKEN }, raw_input: TRANSFER_DATA };
+        return {
+            to: { hash: TOKEN },
+            raw_input: TRANSFER_DATA,
+            block_number: 100,
+        };
     }
     return { items: [] };
 }
@@ -140,6 +158,7 @@ beforeEach(() => {
     globalThis.document = makeDocument();
     globalThis.window = { location: { search: "" } };
     state.blockscoutUrl = EXPLORER;
+    state.networkEndpoints = {};
     state.wallets = [
         {
             name: "Main",
@@ -148,13 +167,18 @@ beforeEach(() => {
         },
     ];
     state.trackedTokens = [{ address: TOKEN, symbol: "TDOL", decimals: 6 }];
+    state.networkTrackedTokens = {};
     state.viewData = {};
     state.viewStack = [];
     state.currentView = null;
 });
 
 test("a token transfer's decoded details name the token contract and the amount at its scale", async () => {
-    const [row] = await fetchRecentTransactions(HOLDER, EXPLORER, 1);
+    const [row] = await fetchRecentTransactions(
+        HOLDER,
+        EXPLORER,
+        NETWORKS.mainnet.chainId,
+    );
     expect(row.to).toBe(RECIPIENT);
     expect(row.contractAddress).toBe(TOKEN.toLowerCase());
 
@@ -174,3 +198,96 @@ test("a token transfer's decoded details name the token contract and the amount
         '<div class="font-bold">1234.5000 TDOL</div>',
     );
 });
+
+// Mainnet is active, and its Blockscout knows nothing of the transaction. The
+// row was read from the Blockscout Settings remembers for Sepolia, and the
+// screen reads the transaction from there too, so every link on it is drawn.
+test("with mainnet active, a Sepolia transaction is read from Sepolia's Blockscout and its links open the Sepolia explorer", async () => {
+    state.networkId = "mainnet";
+    state.blockscoutUrl = OTHER_EXPLORER;
+    state.networkEndpoints = { sepolia: { blockscoutUrl: EXPLORER } };
+    const [row] = await fetchRecentTransactions(
+        HOLDER,
+        EXPLORER,
+        NETWORKS.sepolia.chainId,
+    );
+
+    transactionDetail.show(row);
+    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+
+    const sepolia = "https://sepolia.etherscan.io";
+    const links = (id) =>
+        [...node(id).innerHTML.matchAll(/href="([^"]*)"/g)].map((m) => m[1]);
+    expect(links("tx-detail-hash")).toEqual([`${sepolia}/tx/${TX_HASH}`]);
+    expect(links("tx-detail-from")).toEqual([`${sepolia}/address/${HOLDER}`]);
+    expect(links("tx-detail-to")).toEqual([`${sepolia}/address/${RECIPIENT}`]);
+    expect(links("tx-detail-token-contract")).toEqual([
+        `${sepolia}/token/${TOKEN.toLowerCase()}`,
+    ]);
+    expect(links("tx-detail-block")).toEqual([`${sepolia}/block/100`]);
+    expect(links("tx-detail-calldata-details")).toEqual([
+        `${sepolia}/address/${TOKEN}`,
+        `${sepolia}/address/${RECIPIENT}`,
+    ]);
+});
+
+test("with mainnet active and no Blockscout remembered for Sepolia, a Sepolia transaction is asked of Sepolia's default Blockscout", async () => {
+    state.networkId = "mainnet";
+    state.blockscoutUrl = OTHER_EXPLORER;
+    const [row] = await fetchRecentTransactions(
+        HOLDER,
+        EXPLORER,
+        NETWORKS.sepolia.chainId,
+    );
+    mockAsked.length = 0;
+
+    transactionDetail.show(row);
+    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+
+    expect(mockAsked).toEqual([
+        NETWORKS.sepolia.defaultBlockscoutUrl + "/transactions/" + TX_HASH,
+    ]);
+});
+
+// Open the Sepolia transfer's detail screen with mainnet active, and wait for
+// its decoded details.
+async function showSepoliaTransferWithMainnetActive() {
+    state.networkId = "mainnet";
+    state.blockscoutUrl = OTHER_EXPLORER;
+    state.networkEndpoints = { sepolia: { blockscoutUrl: EXPLORER } };
+    const [row] = await fetchRecentTransactions(
+        HOLDER,
+        EXPLORER,
+        NETWORKS.sepolia.chainId,
+    );
+    transactionDetail.show(row);
+    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+}
+
+test("with mainnet active, a Sepolia token transfer's decoded details name the token tracked on Sepolia and its amount at its scale", async () => {
+    state.trackedTokens = [];
+    state.networkTrackedTokens = {
+        sepolia: [{ address: TOKEN, symbol: "TDOL", decimals: 6 }],
+    };
+    await showSepoliaTransferWithMainnetActive();
+
+    expect(decodedLine("Token")).toContain('<div class="font-bold">TDOL</div>');
+    expect(decodedLine("Amount")).toContain(
+        '<div class="font-bold">1234.5000 TDOL</div>',
+    );
+});
+
+// The same contract address on mainnet is another token, so what the wallet
+// tracks and holds there names nothing on Sepolia.
+test("with mainnet active, a Sepolia token transfer's decoded details take nothing from mainnet's tracked tokens or balances", async () => {
+    state.trackedTokens = [{ address: TOKEN, symbol: "MDOL", decimals: 18 }];
+    state.wallets[0].addresses[0].tokenBalances = [
+        { address: TOKEN, symbol: "MDOL", decimals: 18, balance: "1.0" },
+    ];
+    await showSepoliaTransferWithMainnetActive();
+
+    expect(decodedLine("Token")).not.toContain("MDOL");
+    expect(decodedLine("Amount")).toContain(
+        '<div class="font-bold">1234500000 base units (decimals unknown)</div>',
+    );
+});

tests/trackedTokensPerNetwork.test.js

@@ -0,0 +1,372 @@
+// Tracked tokens are kept per network, and the two add-token screens offer the
+// bundled token list, which holds Ethereum Mainnet contracts, on Ethereum
+// Mainnet only (https://git.eeqj.de/sneak/AutistMask/issues/523), including on
+// the screen "Back" lands on after a switch made from the Settings gear and for
+// a contract lookup that answers after one. Driven through the real popup over
+// a stored profile; the same switch made by the background is in
+// tests/coldWorkerChainSwitch.test.js.
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+    ADDRESS,
+    TOKEN_ADDRESS,
+} = require("./support/popupBoot");
+const { NETWORKS } = require("../src/shared/networks");
+
+const SEPOLIA_TOKEN = {
+    address: TOKEN_ADDRESS,
+    symbol: "TST",
+    decimals: 18,
+    name: "Test Token",
+};
+const MAINNET_TOKEN = {
+    address: "0x6B175474E89094C44Da98b954EedeAC495271d0F",
+    symbol: "DAI",
+    decimals: 18,
+    name: "Dai Stablecoin",
+};
+// Tracked on neither network.
+const NEW_TOKEN_ADDRESS = "0xBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB";
+const NETWORK_CHANGED_FLASH =
+    "The active network changed before the lookup finished, so the token was" +
+    " not added.";
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+// The popup reopened onto SettingsAddToken, on `networkId`.
+function bootOnAddToken(networkId, extra) {
+    return bootPopup(
+        unversionedValidProfile({
+            networkId,
+            currentView: "settings-addtoken",
+            ...extra,
+        }),
+    );
+}
+
+// The popup reopened onto AddressDetail on Ethereum Mainnet, with DAI tracked
+// there and TST tracked on Sepolia.
+function bootOnAddress() {
+    return bootPopup(
+        unversionedValidProfile({
+            currentView: "address",
+            selectedWallet: 0,
+            selectedAddress: 0,
+            trackedTokens: [MAINNET_TOKEN],
+            networkTrackedTokens: { sepolia: [SEPOLIA_TOKEN] },
+        }),
+    );
+}
+
+// The popup reopened onto AddressToken for `token`, with AddressDetail beneath
+// it, over the same tracked tokens as bootOnAddress().
+function bootOnToken(token) {
+    return bootPopup(
+        unversionedValidProfile({
+            currentView: "address-token",
+            viewStack: ["main", "address"],
+            selectedWallet: 0,
+            selectedAddress: 0,
+            selectedToken: token,
+            trackedTokens: [MAINNET_TOKEN],
+            networkTrackedTokens: { sepolia: [SEPOLIA_TOKEN] },
+        }),
+    );
+}
+
+// AddressToken for `token` opened from AddressDetail, as tapping the token's
+// row there does.
+async function openToken(boot, token) {
+    const { state } = require("../src/shared/state");
+    state.selectedToken = token;
+    require("../src/popup/views/helpers").pushCurrentView();
+    require("../src/popup/views/addressToken").show();
+    await boot.settle();
+}
+
+// Presses `addButton` with a contract lookup that answers only after the
+// Settings gear and a switch to `networkId`.
+async function addAcrossSwitch(boot, addButton, networkId) {
+    const { lookupTokenInfo } = require("../src/shared/balances");
+    let answer;
+    lookupTokenInfo.mockImplementationOnce(
+        () =>
+            new Promise((resolve) => {
+                answer = resolve;
+            }),
+    );
+    const adding = boot.click(addButton);
+    await boot.click("btn-settings");
+    await chooseNetwork(boot, networkId);
+    answer({ symbol: "NEW", decimals: 18, name: "New Token" });
+    await adding;
+}
+
+// Picks `networkId` in the Settings network selector, as the user does.
+async function chooseNetwork(boot, networkId) {
+    const select = boot.node("settings-network");
+    select.value = networkId;
+    for (const fn of select.listeners.change) await fn();
+    await boot.settle();
+}
+
+// The Settings gear, a switch to Sepolia, and Back.
+async function gearSwitchBack(boot) {
+    await boot.click("btn-settings");
+    expect(boot.visibleViews()).toEqual(["settings"]);
+    await chooseNetwork(boot, "sepolia");
+    await boot.click("btn-settings-back");
+}
+
+describe.each([
+    ["mainnet", false],
+    ["sepolia", true],
+])("on %s", (networkId, hidden) => {
+    test(`the common tokens are hidden: ${hidden}`, async () => {
+        const boot = await bootOnAddToken(networkId);
+        expect(boot.pageErrors).toEqual([]);
+        expect(boot.visibleViews()).toEqual(["settings-addtoken"]);
+        expect(boot.hidden("settings-addtoken-common")).toBe(hidden);
+
+        require("../src/popup/views/addToken").show();
+        expect(boot.visibleViews()).toEqual(["add-token"]);
+        expect(boot.hidden("add-token-common")).toBe(hidden);
+    });
+});
+
+test("a token added by contract address on Sepolia is tracked on Sepolia only", async () => {
+    const boot = await bootOnAddToken("sepolia", {
+        networkTrackedTokens: { mainnet: [MAINNET_TOKEN] },
+    });
+    const stored = () => boot.storage.read("autistmask");
+    const { lookupTokenInfo } = require("../src/shared/balances");
+    lookupTokenInfo.mockResolvedValueOnce({
+        symbol: SEPOLIA_TOKEN.symbol,
+        decimals: SEPOLIA_TOKEN.decimals,
+        name: SEPOLIA_TOKEN.name,
+    });
+
+    boot.node("settings-addtoken-address").value = TOKEN_ADDRESS;
+    await boot.click("btn-settings-addtoken-manual");
+
+    expect(lookupTokenInfo).toHaveBeenCalledWith(
+        TOKEN_ADDRESS,
+        expect.any(String),
+        "sepolia",
+        expect.anything(),
+    );
+    expect(stored().trackedTokens).toEqual([SEPOLIA_TOKEN]);
+
+    await chooseNetwork(boot, "mainnet");
+    expect(stored().networkId).toBe("mainnet");
+    expect(stored().trackedTokens).toEqual([MAINNET_TOKEN]);
+    const onMainnet = boot.node("settings-tracked-tokens").innerHTML;
+    expect(onMainnet).toContain("DAI");
+    expect(onMainnet).not.toContain("TST");
+
+    await chooseNetwork(boot, "sepolia");
+    expect(stored().networkId).toBe("sepolia");
+    expect(stored().trackedTokens).toEqual([SEPOLIA_TOKEN]);
+    const onSepolia = boot.node("settings-tracked-tokens").innerHTML;
+    expect(onSepolia).toContain("TST");
+    expect(onSepolia).not.toContain("DAI");
+});
+
+describe("Back after a switch from the Settings gear", () => {
+    test("SettingsAddToken no longer offers the common tokens", async () => {
+        const boot = await bootOnAddToken("mainnet");
+        expect(boot.hidden("settings-addtoken-common")).toBe(false);
+
+        await gearSwitchBack(boot);
+        expect(boot.visibleViews()).toEqual(["settings-addtoken"]);
+        expect(boot.hidden("settings-addtoken-common")).toBe(true);
+    });
+
+    test("AddressDetail lists the new network's tracked tokens", async () => {
+        const boot = await bootOnAddress();
+        expect(boot.node("address-balances").innerHTML).toContain("DAI");
+
+        await gearSwitchBack(boot);
+        expect(boot.visibleViews()).toEqual(["address"]);
+        const balances = boot.node("address-balances").innerHTML;
+        expect(balances).toContain("TST");
+        expect(balances).not.toContain("DAI");
+    });
+
+    // Neither can be rendered from saved state, so neither is landed on.
+    test.each([
+        ["btn-add-token", "add-token"],
+        ["btn-send", "send"],
+    ])("from over %s, it lands on AddressDetail", async (button, view) => {
+        const boot = await bootOnAddress();
+        await boot.click(button);
+        expect(boot.visibleViews()).toEqual([view]);
+
+        await gearSwitchBack(boot);
+        expect(boot.visibleViews()).toEqual(["address"]);
+        expect(boot.node("address-balances").innerHTML).not.toContain("DAI");
+    });
+
+    // DAI was picked on Ethereum Mainnet, where alone it is tracked.
+    test.each([
+        [
+            "opened from AddressDetail",
+            async () => {
+                const boot = await bootOnAddress();
+                await openToken(boot, MAINNET_TOKEN.address);
+                return boot;
+            },
+        ],
+        ["in a reopened popup", () => bootOnToken(MAINNET_TOKEN.address)],
+    ])(
+        "from AddressToken for DAI %s, it lands on AddressDetail",
+        async (_how, open) => {
+            const boot = await open();
+            expect(boot.visibleViews()).toEqual(["address-token"]);
+            expect(boot.text("address-token-title")).toContain("DAI");
+
+            await gearSwitchBack(boot);
+            expect(boot.visibleViews()).toEqual(["address"]);
+            const balances = boot.node("address-balances").innerHTML;
+            expect(balances).toContain("TST");
+            expect(balances).not.toContain("DAI");
+        },
+    );
+
+    // The stack is saved cut with the switch, so a popup closed straight after
+    // it and reopened onto Settings lands where this one would. Loading a
+    // saved stack cuts it at AddToken and Send as well, but not at
+    // AddressToken.
+    test.each([
+        [
+            "AddressToken for DAI",
+            (boot) => openToken(boot, MAINNET_TOKEN.address),
+        ],
+        ["AddToken", (boot) => boot.click("btn-add-token")],
+        ["Send", (boot) => boot.click("btn-send")],
+    ])(
+        "from %s, a popup reopened after the switch lands on AddressDetail",
+        async (_view, open) => {
+            const boot = await bootOnAddress();
+            await open(boot);
+            await boot.click("btn-settings");
+            await chooseNetwork(boot, "sepolia");
+
+            const reopened = await bootPopup(boot.storage.read("autistmask"));
+            expect(reopened.visibleViews()).toEqual(["settings"]);
+            await reopened.click("btn-settings-back");
+            expect(reopened.visibleViews()).toEqual(["address"]);
+            const balances = reopened.node("address-balances").innerHTML;
+            expect(balances).toContain("TST");
+            expect(balances).not.toContain("DAI");
+        },
+    );
+
+    test("AddressToken for the native token is drawn again for the new network", async () => {
+        const boot = await bootOnToken("ETH");
+        expect(boot.visibleViews()).toEqual(["address-token"]);
+
+        await gearSwitchBack(boot);
+        expect(boot.visibleViews()).toEqual(["address-token"]);
+        expect(boot.text("address-token-title")).toContain("SepoliaETH");
+    });
+
+    // A popup reopened onto ConfirmTx has no Send beneath it, so "Back" draws
+    // ConfirmTx again from the saved transaction. It is drawn for the network
+    // the transaction was reviewed on, and Sign & Send refuses it on the new
+    // one.
+    test("ConfirmTx reviewed on Sepolia is not sent on Ethereum Mainnet", async () => {
+        const boot = await bootPopup(
+            unversionedValidProfile({
+                networkId: "sepolia",
+                currentView: "confirm-tx",
+                selectedWallet: 0,
+                selectedAddress: 0,
+                viewData: {
+                    pendingTx: {
+                        token: "ETH",
+                        from: ADDRESS,
+                        to: ADDRESS,
+                        amount: "1",
+                        chainId: NETWORKS.sepolia.chainId,
+                    },
+                },
+            }),
+        );
+        expect(boot.visibleViews()).toEqual(["confirm-tx"]);
+
+        await boot.click("btn-settings");
+        await chooseNetwork(boot, "mainnet");
+        globalThis.fetch.mockClear();
+        await boot.click("btn-settings-back");
+        expect(boot.visibleViews()).toEqual(["confirm-tx"]);
+        // Drawn again: its Etherscan label check asks Sepolia's explorer.
+        expect(globalThis.fetch.mock.calls.map((call) => call[0])).toEqual([
+            NETWORKS.sepolia.explorerUrl + "/address/" + ADDRESS,
+        ]);
+        expect(boot.text("confirm-type")).toBe("Native SepoliaETH transfer");
+
+        boot.node("confirm-tx-password").value = "any password";
+        await boot.click("btn-confirm-send");
+        expect(boot.visibleViews()).toEqual(["confirm-tx"]);
+        expect(
+            boot.node("confirm-network-changed-error").style.visibility,
+        ).toBe("visible");
+        // Refused before the password is even tried.
+        expect(boot.text("confirm-tx-password-error")).toBe("");
+    });
+
+    test("without a wallet, it lands on Welcome", async () => {
+        const boot = await bootPopup(undefined);
+        expect(boot.visibleViews()).toEqual(["welcome"]);
+
+        await gearSwitchBack(boot);
+        expect(boot.visibleViews()).toEqual(["welcome"]);
+    });
+
+    test("a later Back onto Settings keeps what was typed there", async () => {
+        const boot = await bootOnAddress();
+        await boot.click("btn-settings");
+        await chooseNetwork(boot, "sepolia");
+        boot.node("settings-rpc").value = "https://typed.example";
+
+        await boot.click("btn-settings-add-token");
+        expect(boot.visibleViews()).toEqual(["settings-addtoken"]);
+        await boot.click("btn-settings-addtoken-back");
+        expect(boot.visibleViews()).toEqual(["settings"]);
+        expect(boot.value("settings-rpc")).toBe("https://typed.example");
+    });
+});
+
+describe("a contract lookup that answers after a switch adds nothing", () => {
+    test("from SettingsAddToken", async () => {
+        const boot = await bootOnAddToken("sepolia", {
+            networkTrackedTokens: { mainnet: [MAINNET_TOKEN] },
+        });
+        const stored = () => boot.storage.read("autistmask");
+        boot.node("settings-addtoken-address").value = NEW_TOKEN_ADDRESS;
+
+        await addAcrossSwitch(boot, "btn-settings-addtoken-manual", "mainnet");
+        expect(boot.visibleViews()).toEqual(["settings"]);
+        expect(boot.text("flash-msg")).toBe(NETWORK_CHANGED_FLASH);
+        expect(stored().trackedTokens).toEqual([MAINNET_TOKEN]);
+        expect(stored().networkTrackedTokens.sepolia).toEqual([]);
+    });
+
+    test("from AddToken", async () => {
+        const boot = await bootOnAddress();
+        const stored = () => boot.storage.read("autistmask");
+        await boot.click("btn-add-token");
+        boot.node("add-token-address").value = NEW_TOKEN_ADDRESS;
+
+        await addAcrossSwitch(boot, "btn-add-token-confirm", "sepolia");
+        expect(boot.visibleViews()).toEqual(["settings"]);
+        expect(boot.text("flash-msg")).toBe(NETWORK_CHANGED_FLASH);
+        expect(stored().trackedTokens).toEqual([SEPOLIA_TOKEN]);
+        expect(stored().networkTrackedTokens.mainnet).toEqual([MAINNET_TOKEN]);
+    });
+});

tests/txStatus.test.js

@@ -29,8 +29,13 @@ jest.mock("../src/shared/log", () => ({
 }));
 
 const mockReceiptLookup = jest.fn();
+// The RPC URL and network of every node a wait was given.
+const mockNodes = [];
 jest.mock("../src/shared/balances", () => ({
-    getProvider: () => ({ getTransactionReceipt: mockReceiptLookup }),
+    getProvider: (rpcUrl, networkId) => {
+        mockNodes.push({ rpcUrl, networkId });
+        return { getTransactionReceipt: mockReceiptLookup };
+    },
     refreshBalances: jest.fn(),
 }));
 
@@ -107,6 +112,7 @@ global.chrome = { storage };
 
 const txStatus = require("../src/popup/views/txStatus");
 const { state } = require("../src/shared/state");
+const { NETWORKS } = require("../src/shared/networks");
 const { RESTORABLE_VIEWS } = require("../src/shared/restorableViews");
 const { log } = require("../src/shared/log");
 
@@ -118,6 +124,7 @@ const TX_INFO = {
     amount: "0.0050",
     token: "ETH",
     tokenSymbol: null,
+    chainId: NETWORKS.mainnet.chainId,
 };
 
 // True when a view element is not hidden.
@@ -137,8 +144,14 @@ beforeEach(() => {
     jest.setSystemTime(new Date("2026-08-11T12:00:00Z"));
     elements.clear();
     mockReceiptLookup.mockReset();
+    mockNodes.length = 0;
     log.errorf.mockClear();
+    state.networkId = "mainnet";
+    state.rpcUrl = NETWORKS.mainnet.defaultRpcUrl;
+    state.networkEndpoints = {};
     state.wallets = [];
+    state.trackedTokens = [];
+    state.networkTrackedTokens = {};
     state.viewData = {};
     state.viewStack = [];
     state.currentView = null;
@@ -349,14 +362,14 @@ describe("WaitTx persistence across popup close", () => {
             // out of restoreView().
             {
                 hash: TX_HASH,
-                txInfo: { to: 42, amount: "0.0050" },
+                txInfo: { ...TX_INFO, to: 42 },
                 broadcastTime: Date.now(),
             },
             // Otherwise complete but an array: only Array.isArray() rejects
             // it, since typeof [] is "object" and the fields are present.
             {
                 hash: TX_HASH,
-                txInfo: Object.assign([], { to: RECIPIENT, amount: "0.0050" }),
+                txInfo: Object.assign([], TX_INFO),
                 broadcastTime: Date.now(),
             },
             {
@@ -364,6 +377,18 @@ describe("WaitTx persistence across popup close", () => {
                 txInfo: { to: RECIPIENT },
                 broadcastTime: Date.now(),
             },
+            // Otherwise complete but for a chain id naming no network: there
+            // is no node to ask for the receipt, and no explorer to link to.
+            {
+                hash: TX_HASH,
+                txInfo: { ...TX_INFO, chainId: undefined },
+                broadcastTime: Date.now(),
+            },
+            {
+                hash: TX_HASH,
+                txInfo: { ...TX_INFO, chainId: "0x5" },
+                broadcastTime: Date.now(),
+            },
         ]) {
             state.viewData = { pendingWait: bad };
             expect(txStatus.restoreWait()).toBe(false);
@@ -499,6 +524,154 @@ describe("WaitTx when the popup closes", () => {
     });
 });
 
+// The popup can reopen onto WaitTx after Settings switched the network. The
+// wait asked the active network's node for the receipt, never found it, and
+// reported a timeout, and its links went to the active network's explorer
+// (https://git.eeqj.de/sneak/AutistMask/issues/584).
+describe("WaitTx for a Sepolia transaction with mainnet active", () => {
+    const SEPOLIA_NODE = "https://sepolia.node.example.invalid";
+    const sepoliaTx = { ...TX_INFO, chainId: NETWORKS.sepolia.chainId };
+
+    beforeEach(() => {
+        state.rpcUrl = "https://mainnet.node.example.invalid";
+        state.networkEndpoints = { sepolia: { rpcUrl: SEPOLIA_NODE } };
+    });
+
+    test("the receipt is asked of the Sepolia node Settings has", async () => {
+        mockReceiptLookup.mockResolvedValue({ blockNumber: 21000000 });
+        state.viewData = {
+            pendingWait: {
+                txInfo: sepoliaTx,
+                hash: TX_HASH,
+                broadcastTime: Date.now(),
+            },
+        };
+        expect(txStatus.restoreWait()).toBe(true);
+        await jest.advanceTimersByTimeAsync(0);
+
+        expect(mockNodes).toEqual([
+            { rpcUrl: SEPOLIA_NODE, networkId: "sepolia" },
+        ]);
+        expect(state.currentView).toBe("success-tx");
+    });
+
+    test("the recipient and hash link to the Sepolia explorer", () => {
+        mockReceiptLookup.mockResolvedValue(null);
+        txStatus.showWait(sepoliaTx, TX_HASH);
+
+        expect(getElement("wait-tx-to").innerHTML).toContain(
+            `href="https://sepolia.etherscan.io/address/${RECIPIENT}"`,
+        );
+        expect(getElement("wait-tx-hash").innerHTML).toContain(
+            `href="https://sepolia.etherscan.io/tx/${TX_HASH}"`,
+        );
+    });
+});
+
+// SuccessTx and ErrorTx follow WaitTx and describe the same transaction, but
+// their links went to the active network's explorer
+// (https://git.eeqj.de/sneak/AutistMask/issues/622). Each test checks the
+// screen again after rendering it from its stored view data alone, as a
+// reopened popup does.
+describe("SuccessTx and ErrorTx for a Sepolia transaction with mainnet active", () => {
+    const SEPOLIA_EXPLORER = "https://sepolia.etherscan.io";
+    const TOKEN = "0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238";
+    const sepoliaTx = { ...TX_INFO, chainId: NETWORKS.sepolia.chainId };
+
+    test("the recipient, block and hash on SuccessTx link to the Sepolia explorer", async () => {
+        function expectSepoliaLinks() {
+            expect(getElement("success-tx-to").innerHTML).toContain(
+                `href="${SEPOLIA_EXPLORER}/address/${RECIPIENT}"`,
+            );
+            expect(getElement("success-tx-block").innerHTML).toContain(
+                `href="${SEPOLIA_EXPLORER}/block/21000000"`,
+            );
+            expect(getElement("success-tx-hash").innerHTML).toContain(
+                `href="${SEPOLIA_EXPLORER}/tx/${TX_HASH}"`,
+            );
+        }
+        mockReceiptLookup.mockResolvedValue({ blockNumber: 21000000 });
+        txStatus.showWait(sepoliaTx, TX_HASH);
+        await jest.advanceTimersByTimeAsync(10000);
+        expect(state.currentView).toBe("success-tx");
+        expectSepoliaLinks();
+
+        elements.clear();
+        txStatus.renderSuccess();
+        expectSepoliaLinks();
+    });
+
+    test("the addresses in SuccessTx's decoded action link to the Sepolia explorer", async () => {
+        function expectSepoliaLinks() {
+            const html = getElement("success-tx-decoded").innerHTML;
+            expect(html).toContain(
+                `href="${SEPOLIA_EXPLORER}/address/${TOKEN}"`,
+            );
+            expect(html).toContain(
+                `href="${SEPOLIA_EXPLORER}/address/${RECIPIENT}"`,
+            );
+        }
+        const decoded = {
+            name: "Transfer",
+            details: [
+                { label: "Token", address: TOKEN, isToken: true },
+                { label: "Recipient", address: RECIPIENT },
+            ],
+        };
+        mockReceiptLookup.mockResolvedValue({ blockNumber: 21000000 });
+        txStatus.showWait({ ...sepoliaTx, decoded }, TX_HASH);
+        await jest.advanceTimersByTimeAsync(10000);
+        expect(state.currentView).toBe("success-tx");
+        expectSepoliaLinks();
+
+        elements.clear();
+        txStatus.renderSuccess();
+        expectSepoliaLinks();
+    });
+
+    // https://git.eeqj.de/sneak/AutistMask/issues/629
+    test("SuccessTx's decoded action names the token from the tokens tracked on Sepolia", async () => {
+        function expectTokenNamed() {
+            expect(getElement("success-tx-decoded").innerHTML).toContain(
+                '<div class="font-bold">TDOL</div>',
+            );
+        }
+        state.networkTrackedTokens = {
+            sepolia: [{ address: TOKEN, symbol: "TDOL", decimals: 6 }],
+        };
+        const decoded = {
+            name: "Transfer",
+            details: [{ label: "Token", address: TOKEN, isToken: true }],
+        };
+        mockReceiptLookup.mockResolvedValue({ blockNumber: 21000000 });
+        txStatus.showWait({ ...sepoliaTx, decoded }, TX_HASH);
+        await jest.advanceTimersByTimeAsync(10000);
+        expect(state.currentView).toBe("success-tx");
+        expectTokenNamed();
+
+        elements.clear();
+        txStatus.renderSuccess();
+        expectTokenNamed();
+    });
+
+    test("the recipient and hash on ErrorTx link to the Sepolia explorer", () => {
+        function expectSepoliaLinks() {
+            expect(getElement("error-tx-to").innerHTML).toContain(
+                `href="${SEPOLIA_EXPLORER}/address/${RECIPIENT}"`,
+            );
+            expect(getElement("error-tx-hash").innerHTML).toContain(
+                `href="${SEPOLIA_EXPLORER}/tx/${TX_HASH}"`,
+            );
+        }
+        txStatus.showError(sepoliaTx, TX_HASH, "The transaction failed.");
+        expectSepoliaLinks();
+
+        elements.clear();
+        txStatus.renderError();
+        expectSepoliaLinks();
+    });
+});
+
 describe("wait-tx is a view the popup may reopen onto", () => {
     // The resume feature is wired through RESTORABLE_VIEWS: restoreView()
     // refuses any view not in the set, so dropping "wait-tx" from it kills

tests/uniswapRouterAddress.test.js

@@ -0,0 +1,381 @@
+// Which transactions are shown as a swap through the Uniswap Universal Router
+// (https://git.eeqj.de/sneak/AutistMask/issues/520).
+//
+// The decoder used to recognise the router's execute() call by its selector
+// alone, so the same calldata sent to an ordinary address was shown as a swap
+// through the router, with that address as its Protocol. It is now decoded
+// only when the transaction is sent to a Universal Router deployment on the
+// network it is for; anywhere else it is left to the raw data.
+//
+// The transaction history labelled any call named `execute` or `multicall` a
+// Swap, whatever address it went to
+// (https://git.eeqj.de/sneak/AutistMask/issues/580). It now does so only for
+// such a call sent to a Universal Router deployment on the network the
+// transaction is on; any other is labelled by its method name.
+//
+// The transaction detail screen and the approval screen are driven against a
+// minimal DOM stub in the shape tests/tokenTransferDetail.test.js uses, the
+// approval screen opened the way tests/swapStatusAmount.test.js opens it.
+
+const { AbiCoder, Interface, getAddress, solidityPacked } = require("ethers");
+
+jest.mock("../src/shared/log", () => ({
+    log: {
+        debugf: () => {},
+        infof: () => {},
+        warnf: () => {},
+        errorf: () => {},
+    },
+    debugFetch: async (url) => ({
+        ok: true,
+        json: async () => mockExplorerAnswer(url),
+    }),
+    setRuntimeDebug: () => {},
+    isDebug: () => false,
+}));
+
+globalThis.chrome = {
+    storage: { local: { get: async () => ({}), set: async () => {} } },
+};
+
+const { state } = require("../src/shared/state");
+const { fetchRecentTransactions } = require("../src/shared/transactions");
+const approval = require("../src/popup/views/approval");
+const { decodeCalldata } = approval;
+const transactionDetail = require("../src/popup/views/transactionDetail");
+
+const MAINNET = "0x1";
+const SEPOLIA = "0xaa36a7";
+
+// From Uniswap's deployment files: one router on Ethereum Mainnet only, one on
+// Sepolia only, and one at the same address on both.
+const MAINNET_ROUTER = "0x66a9893cc07d91d95644aedd05d03f95e1dba8af";
+const SEPOLIA_ROUTER = "0x3a9d48ab9751398bbfa63ad67599bb04e4bdf98b";
+const ROUTER_ON_BOTH = "0x3fC91A3afd70395Cd496C647d5a6CC9D4B2b7FAD";
+// The address with no code from the issue.
+const ORDINARY = "0x0b0050Da68435b3EcBC236c40F16dB2070bCD79A";
+// A contract that is not a router, such as a multisig.
+const OTHER_CONTRACT = "0x5afe000000000000000000000000000000005afe";
+
+const RECIPIENT = "0xC0FfEE0000000000000000000000000000c0fFEe";
+const SEPOLIA_WETH = "0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14";
+const TOKEN = "0xE2E0000000000000000000000000000000000E2e";
+const HUNDREDTH_ETH = 10000000000000000n;
+
+const coder = AbiCoder.defaultAbiCoder();
+const routerIface = new Interface([
+    "function execute(bytes commands, bytes[] inputs, uint256 deadline)",
+]);
+
+// The calldata from the issue: wrap 0.01 ETH, then a V3 swap of it into a
+// token.
+const SWAP_DATA = routerIface.encodeFunctionData("execute", [
+    solidityPacked(["uint8", "uint8"], [0x0b, 0x00]),
+    [
+        coder.encode(["address", "uint256"], [RECIPIENT, HUNDREDTH_ETH]),
+        coder.encode(
+            ["address", "uint256", "uint256", "bytes", "bool"],
+            [
+                RECIPIENT,
+                HUNDREDTH_ETH,
+                1n,
+                solidityPacked(
+                    ["address", "uint24", "address"],
+                    [SEPOLIA_WETH, 3000, TOKEN],
+                ),
+                false,
+            ],
+        ),
+    ],
+    9999999999n,
+]);
+
+beforeEach(() => {
+    state.trackedTokens = [];
+    state.wallets = [];
+});
+
+describe("execute() calldata on the approval screen's decoder", () => {
+    test("sent to a router on the transaction's network, it is a swap", () => {
+        const onMainnet = decodeCalldata(SWAP_DATA, MAINNET_ROUTER, MAINNET);
+        expect(onMainnet.description).toBe("Swap via Uniswap Universal Router");
+        expect(onMainnet.details[0]).toMatchObject({
+            label: "Protocol",
+            address: MAINNET_ROUTER,
+        });
+        expect(
+            decodeCalldata(SWAP_DATA, SEPOLIA_ROUTER, SEPOLIA).description,
+        ).toBe("Swap via Uniswap Universal Router");
+    });
+
+    test("sent to an ordinary address, it is not decoded", () => {
+        expect(decodeCalldata(SWAP_DATA, ORDINARY, MAINNET)).toBeNull();
+        expect(decodeCalldata(SWAP_DATA, ORDINARY, SEPOLIA)).toBeNull();
+    });
+
+    test("sent to a router of the other network only, it is not decoded", () => {
+        expect(decodeCalldata(SWAP_DATA, SEPOLIA_ROUTER, MAINNET)).toBeNull();
+        expect(decodeCalldata(SWAP_DATA, MAINNET_ROUTER, SEPOLIA)).toBeNull();
+    });
+
+    test("a router deployed at the same address on both networks is one on each", () => {
+        expect(
+            decodeCalldata(SWAP_DATA, ROUTER_ON_BOTH, MAINNET),
+        ).not.toBeNull();
+        expect(
+            decodeCalldata(SWAP_DATA, ROUTER_ON_BOTH, SEPOLIA),
+        ).not.toBeNull();
+    });
+
+    test("the router address matches in any letter case", () => {
+        const upper = "0x" + MAINNET_ROUTER.slice(2).toUpperCase();
+        for (const address of [getAddress(MAINNET_ROUTER), upper]) {
+            expect(decodeCalldata(SWAP_DATA, address, MAINNET)).not.toBeNull();
+        }
+    });
+});
+
+// The transaction the explorer reports: SWAP_DATA, sent to `mockSentTo`.
+const TX_HASH = "0x" + "5".repeat(64);
+let mockSentTo = null;
+// The transactions the explorer reports for RECIPIENT's history.
+let mockHistory = [];
+
+function mockExplorerAnswer(url) {
+    if (url.endsWith("/addresses/" + RECIPIENT + "/transactions")) {
+        return { items: mockHistory };
+    }
+    if (url.endsWith("/transactions/" + TX_HASH)) {
+        return {
+            to: { hash: mockSentTo },
+            raw_input: SWAP_DATA,
+            method: "execute",
+        };
+    }
+    return {};
+}
+
+function makeElement(id) {
+    const classes = new Set();
+    const el = {
+        id,
+        textContent: "",
+        value: "",
+        innerHTML: "",
+        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: () => false,
+        },
+        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 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);
+}
+
+// Open the transaction detail screen with `activeNetworkId` active, for the
+// history row `row`, and wait for its decoded details.
+async function showDetail(row, activeNetworkId) {
+    mockSentTo = row.to;
+    globalThis.document = makeDocument();
+    globalThis.window = { location: { search: "" } };
+    state.networkId = activeNetworkId;
+    state.blockscoutUrl = "https://explorer.example/api/v2";
+    state.viewData = {};
+    state.viewStack = [];
+    state.currentView = null;
+    transactionDetail.show(row);
+    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+}
+
+// Open the transaction detail screen with `activeNetworkId` active, for the
+// Sepolia transaction the explorer reports sent to `sentTo`, and wait for its
+// decoded details.
+async function showDetailSentTo(sentTo, activeNetworkId) {
+    await showDetail(
+        {
+            hash: TX_HASH,
+            from: RECIPIENT,
+            to: sentTo,
+            value: "",
+            symbol: "SepoliaETH",
+            timestamp: 1790000000,
+            isError: false,
+            direction: "contract",
+            directionLabel: "Swap",
+            method: "execute",
+            chainId: SEPOLIA,
+        },
+        activeNetworkId,
+    );
+}
+
+describe("execute() calldata on the transaction detail screen", () => {
+    test("sent to a router on the active network, it is a swap", async () => {
+        await showDetailSentTo(SEPOLIA_ROUTER, "sepolia");
+        expect(node("tx-detail-calldata-details").innerHTML).toContain(
+            "Swap via Uniswap Universal Router",
+        );
+    });
+
+    // https://git.eeqj.de/sneak/AutistMask/issues/623
+    test("sent to a router on its network, with the other network active, it is a swap", async () => {
+        await showDetailSentTo(SEPOLIA_ROUTER, "mainnet");
+        expect(node("tx-detail-calldata-details").innerHTML).toContain(
+            "Swap via Uniswap Universal Router",
+        );
+    });
+
+    test("sent to an ordinary address, it is not decoded", async () => {
+        await showDetailSentTo(ORDINARY, "sepolia");
+        expect(node("tx-detail-calldata-action").textContent).toBe("execute");
+        expect(node("tx-detail-calldata-details").innerHTML).toBe("");
+        expect(node("tx-detail-rawdata").innerHTML).toContain(SWAP_DATA);
+    });
+
+    test("sent to a router of the other network only, it is not decoded", async () => {
+        await showDetailSentTo(MAINNET_ROUTER, "sepolia");
+        expect(node("tx-detail-calldata-action").textContent).toBe("execute");
+        expect(node("tx-detail-calldata-details").innerHTML).toBe("");
+        expect(node("tx-detail-rawdata").innerHTML).toContain(SWAP_DATA);
+    });
+});
+
+// The history row made from the explorer's answer for RECIPIENT's `method`
+// call sent to the contract `sentTo` on the network with `chainId`. The
+// explorer gives the address in checksummed form.
+async function historyRow(method, sentTo, chainId) {
+    mockHistory = [
+        {
+            hash: TX_HASH,
+            block_number: 7000000,
+            timestamp: "2026-09-01T00:00:00Z",
+            from: { hash: RECIPIENT },
+            to: { hash: getAddress(sentTo), is_contract: true },
+            value: "0",
+            method,
+            status: "ok",
+        },
+    ];
+    const rows = await fetchRecentTransactions(
+        RECIPIENT,
+        "https://explorer.example/api/v2",
+        chainId,
+    );
+    return rows[0];
+}
+
+// The history row's label and TransactionDetail's Type line, for a Sepolia
+// transaction. The active network does not decide either.
+describe.each([
+    ["execute", "Execute"],
+    ["multicall", "Multicall"],
+])("a %s() call in the history", (method, methodLabel) => {
+    test("sent to a router on its network, it is a Swap", async () => {
+        const row = await historyRow(method, SEPOLIA_ROUTER, SEPOLIA);
+        expect(row.directionLabel).toBe("Swap");
+        await showDetail(row, "mainnet");
+        expect(node("tx-detail-type").textContent).toBe("Swap");
+    });
+
+    test("sent to another contract, it is labelled by its method name", async () => {
+        const row = await historyRow(method, OTHER_CONTRACT, SEPOLIA);
+        expect(row.directionLabel).toBe(methodLabel);
+        await showDetail(row, "sepolia");
+        expect(node("tx-detail-type").textContent).toBe("Contract Call");
+    });
+
+    test("sent to a router of the other network only, it is labelled by its method name", async () => {
+        const row = await historyRow(method, MAINNET_ROUTER, SEPOLIA);
+        expect(row.directionLabel).toBe(methodLabel);
+        await showDetail(row, "mainnet");
+        expect(node("tx-detail-type").textContent).toBe("Contract Call");
+    });
+});
+
+// Open the approval screen with Ethereum Mainnet active, for a site's Sepolia
+// transaction that sends SWAP_DATA to `sentTo`.
+async function showApprovalSentTo(sentTo) {
+    globalThis.document = makeDocument();
+    globalThis.window = { location: { search: "" }, close: () => {} };
+    globalThis.chrome.runtime = {
+        connect: () => ({ postMessage: () => {} }),
+        sendMessage: (_msg, reply) =>
+            reply({
+                type: "tx",
+                origin: "https://dapp.example",
+                isPhishingDomain: false,
+                approvedFrom: RECIPIENT,
+                approvedTx: {
+                    type: 2,
+                    from: RECIPIENT,
+                    chainId: SEPOLIA,
+                    nonce: "0x7",
+                    gasLimit: "0x30d40",
+                    maxPriorityFeePerGas: "0x3b9aca00",
+                    maxFeePerGas: "0x77359400",
+                    to: sentTo,
+                    value: "0x" + HUNDREDTH_ETH.toString(16),
+                    data: SWAP_DATA,
+                    accessList: [],
+                },
+            }),
+    };
+    state.networkId = "mainnet";
+    state.currentView = null;
+    await approval.show(1);
+}
+
+// The router is on Sepolia's list only, so the swap is shown only if the
+// screen decodes for the transaction's network: on Ethereum Mainnet, the
+// active network, that address is not a router.
+describe("execute() calldata on the approval screen, for a Sepolia transaction while Ethereum Mainnet is active", () => {
+    test("sent to a router on Sepolia, it is a swap", async () => {
+        await showApprovalSentTo(SEPOLIA_ROUTER);
+        expect(node("approve-tx-decoded").classList.contains("hidden")).toBe(
+            false,
+        );
+        expect(node("approve-tx-decoded-details").innerHTML).toContain(
+            "Swap via Uniswap Universal Router",
+        );
+    });
+
+    test("sent to an ordinary address, it is shown as raw data", async () => {
+        await showApprovalSentTo(ORDINARY);
+        expect(node("approve-tx-decoded").classList.contains("hidden")).toBe(
+            true,
+        );
+        expect(node("approve-tx-decoded-details").innerHTML).toBe("");
+        expect(node("approve-tx-data").textContent).toBe(SWAP_DATA);
+        expect(
+            node("approve-tx-data-section").classList.contains("hidden"),
+        ).toBe(false);
+    });
+});

tests/uniswapTokenOut.test.js

@@ -53,7 +53,14 @@ function unwrapData() {
 }
 
 function detail(data, label, sources) {
-    const decoded = uniswap.decode(data, ROUTER, sources || {});
+    // Sent by the address the swap pays, so the output is the user's.
+    const decoded = uniswap.decode(
+        data,
+        ROUTER,
+        "0x1",
+        sources || {},
+        RECIPIENT,
+    );
     return decoded.details.find((d) => d.label === label);
 }
 

tests/uniswapUndeterminedTokenIn.test.js

@@ -71,6 +71,8 @@ function exactInParams(currencyIn, path, amountIn, amountOutMin) {
 
 // BALANCE_CHECK_ERC20 (command 0x0e): (address owner, address token,
 // uint256 minBalance). It names the output token and nothing about the input.
+// Its owner is USER, the transaction's sender: a check of any other address
+// names no output token.
 function balanceCheck(token, minBalance) {
     return coder.encode(
         ["address", "address", "uint256"],
@@ -78,8 +80,13 @@ function balanceCheck(token, minBalance) {
     );
 }
 
+// A transaction from USER.
+function decode(data) {
+    return uniswap.decode(data, ROUTER, "0x1", {}, USER);
+}
+
 function detail(data, label) {
-    const decoded = uniswap.decode(data, ROUTER, {});
+    const decoded = decode(data);
     expect(decoded).not.toBeNull();
     return decoded.details.find((d) => d.label === label);
 }
@@ -87,7 +94,7 @@ function detail(data, label) {
 describe("an execute() whose input currency never decoded", () => {
     // A V4_SWAP whose sub-action params do not decode — an action encoding
     // this decoder does not know — leaves every V4 token null. The
-    // BALANCE_CHECK still names the output, so the screen has a Min. received
+    // BALANCE_CHECK still names the output, so the screen has a minimum
     // figure and a Token Out, and previously claimed the user was paying ETH
     // for them.
     const data = () =>
@@ -113,7 +120,7 @@ describe("an execute() whose input currency never decoded", () => {
     });
 
     test("does not name ETH in the swap title either", () => {
-        expect(uniswap.decode(data(), ROUTER, {}).name).toBe("Uniswap Swap");
+        expect(decode(data()).name).toBe("Uniswap Swap");
     });
 });
 
@@ -123,12 +130,13 @@ describe("an execute() that names only an output token", () => {
 
     test("refuses the input rather than defaulting it to ETH", () => {
         expect(detail(data(), "Token In").value).toBe(REFUSAL);
-        expect(uniswap.decode(data(), ROUTER, {}).name).toBe("Uniswap Swap");
+        expect(decode(data()).name).toBe("Uniswap Swap");
     });
 
     test("still states the output it did establish", () => {
         expect(detail(data(), "Token Out").value).toContain("USDT");
-        expect(detail(data(), "Min. received").value).toBe("2.0000 USDT");
+        // No step pays anyone, so the minimum is not said to be received.
+        expect(detail(data(), "Min. paid out").value).toBe("2.0000 USDT");
     });
 });
 
@@ -170,7 +178,7 @@ describe("native ETH in, which V4 spells as the zero address", () => {
 
         expect(detail(data, "Token In").value).toBe("ETH (native)");
         expect(detail(data, "Amount").value).toBe("1.0000 ETH");
-        expect(uniswap.decode(data, ROUTER, {}).name).toBe("Swap ETH → USDT");
+        expect(decode(data).name).toBe("Swap ETH → USDT");
     });
 
     test("WRAP_ETH is still ETH at 18 decimals", () => {

tests/uniswapUndeterminedTokenOut.test.js

@@ -105,7 +105,7 @@ function v3ExactIn(tokenIn, tokenOut, amountIn, amountOutMin) {
 }
 
 function detail(data, label) {
-    const decoded = uniswap.decode(data, ROUTER, {});
+    const decoded = uniswap.decode(data, ROUTER, "0x1", {}, USER);
     expect(decoded).not.toBeNull();
     return decoded.details.find((d) => d.label === label);
 }
@@ -134,13 +134,15 @@ describe("a V4 step that states a Min. received but no output currency", () => {
     });
 
     test("refuses to scale Min. received rather than assuming 18", () => {
-        expect(detail(data(), "Min. received").value).toBe(
+        // With no TAKE, no step pays the user either, so the line is not
+        // labelled received.
+        expect(detail(data(), "Min. paid out").value).toBe(
             unknownDecimalsAmount(MIN_OUT),
         );
     });
 
     test("does not name ETH in the swap title either", () => {
-        const decoded = uniswap.decode(data(), ROUTER, {});
+        const decoded = uniswap.decode(data(), ROUTER, "0x1", {});
         expect(decoded.name).toBe("Uniswap Swap");
     });
 });
@@ -206,6 +208,8 @@ describe("native ETH out, which V4 spells as the zero address", () => {
     test("is still named ETH and still scaled at 18 decimals", () => {
         expect(detail(data(), "Token Out").value).toBe("ETH");
         expect(detail(data(), "Min. received").value).toBe("0.5000 ETH");
-        expect(uniswap.decode(data(), ROUTER, {}).name).toBe("Swap USDT → ETH");
+        expect(uniswap.decode(data(), ROUTER, "0x1", {}).name).toBe(
+            "Swap USDT → ETH",
+        );
     });
 });

tests/uniswapUnknownDecimals.test.js

@@ -82,7 +82,8 @@ function walletsHolding(token, decimals) {
 // decodeCalldata() rather than uniswap.decode() directly, because the scale
 // sources the screen supplies are part of what is under test.
 function swapDetail(data, label) {
-    const decoded = decodeCalldata(data, ROUTER);
+    // Sent by the address the swap pays, so the output is the user's.
+    const decoded = decodeCalldata(data, ROUTER, "0x1", RECIPIENT);
     return decoded.details.find((d) => d.label === label);
 }
 

tests/unknownScaleSend.test.js

@@ -120,7 +120,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const { AbiCoder, parseUnits } = require("ethers");
 const { fetchTokenBalances } = require("../src/shared/balances");
@@ -249,6 +249,12 @@ function errors() {
     return el("confirm-errors").innerHTML;
 }
 
+// The message for an amount the balance does not cover, while it is shown.
+function balanceError() {
+    const box = el("confirm-balance-error");
+    return box.style.visibility === "visible" ? box.textContent : "";
+}
+
 function sendDisabled() {
     return el("btn-confirm-send").disabled;
 }
@@ -319,7 +325,7 @@ describe("the Send screen resolves the scale rather than reading the stored one"
         confirmTx.show(txInfo);
         await settle();
         expect(text("confirm-balance")).toBe("unknown (NOVEL)");
-        expect(errors()).toContain("This token's balance is unknown");
+        expect(balanceError()).toContain("This token's balance is unknown");
         expect(sendDisabled()).toBe(true);
     });
 });
@@ -376,8 +382,7 @@ describe("a scale the explorer's own rows disagree about", () => {
         // confirm-fee-unknown-error — "the network fee could not be
         // estimated... please go back and try again" — as the only explanation
         // for a screen that can never proceed.
-        expect(errors()).not.toBe("");
-        expect(errors()).toContain("This token's balance is unknown");
+        expect(balanceError()).toContain("This token's balance is unknown");
         expect(text("confirm-balance")).toBe("unknown (NOVEL)");
         expect(sendDisabled()).toBe(true);
         // The fee line still reports the estimate as unavailable, because it
@@ -447,6 +452,7 @@ describe("a scale the explorer's own rows disagree about", () => {
         await settle();
         expect(text("confirm-balance")).toBe("5.0000 NOVEL");
         expect(errors()).toBe("");
+        expect(balanceError()).toBe("");
         expect(sendDisabled()).toBe(false);
     });
 });
@@ -476,7 +482,7 @@ describe("the confirmation screen tells an unknown balance from a zero one", ()
             tokenDecimals,
         });
         await settle();
-        return { balance: text("confirm-balance"), errors: errors() };
+        return { balance: text("confirm-balance"), message: balanceError() };
     }
 
     test("the balance line states unknown rather than a quantity of zero", async () => {
@@ -488,16 +494,18 @@ describe("the confirmation screen tells an unknown balance from a zero one", ()
     });
 
     // Both hit INSUFFICIENT_TOKEN — an unknown balance is treated as nothing to
-    // spend from, which is the fail-closed side — but "you have 0.0" is a claim
-    // about the holding, and this one has no established quantity to claim.
-    test("the insufficient-balance message names the reason, not a figure", async () => {
+    // spend from, which is the fail-closed side — but "your balance does not
+    // cover this amount" is a claim about the holding, and this one has no
+    // established quantity to claim.
+    test("the insufficient-balance message names the reason, not a shortfall", async () => {
         const unknown = await render(null);
         const zero = await render(18);
-        expect(unknown.errors).not.toBe(zero.errors);
-        expect(unknown.errors).toContain("This token's balance is unknown");
-        expect(unknown.errors).not.toContain("You have");
-        expect(zero.errors).toContain("You have 0.0000 NOVEL");
-        expect(zero.errors).not.toContain("balance is unknown");
+        expect(unknown.message).toContain("This token's balance is unknown");
+        expect(unknown.message).not.toContain("does not cover");
+        expect(zero.message).toBe(
+            "Your NOVEL balance does not cover this amount. Please go back and" +
+                " send a smaller amount.",
+        );
     });
 });
 

tests/walletDefects.test.js

@@ -475,7 +475,7 @@ describe("every way to a signature or the private key refuses a defective wallet
                 to: RECIPIENT,
                 value: "0x0",
                 data: "0x",
-                chainId: 1,
+                chainId: "0x1",
                 nonce: 0,
                 gasLimit: "21000",
                 maxFeePerGas: "1000000000",