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, each 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) from the read to
the write, through withLock() in src/shared/browserApi.js, and the recovery
screen's reset takes it too. A page in a Firefox private window gets locks of
its own and is not covered. 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
@@ -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
@@ -1156,28 +1179,22 @@ number. They can 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 the step that sets the input side: 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 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, as described below. A V2 exact-out step gives its `amountInMax`, and
-  a V4 swap step the `amountIn` of the swap action that spends its input
-  currency.
+  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
@@ -1193,7 +1210,13 @@ number. They can 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
@@ -1221,17 +1244,33 @@ only when no earlier step set it. It finds each side by three rules:
    `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 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.
+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
@@ -1350,6 +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
@@ -1505,9 +1557,11 @@ 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, except
-ConfirmTx, which keeps the network its transaction was reviewed on, and anything
-typed there and not saved, which belonged to the previous network, is dropped.
+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.
 
@@ -1752,14 +1806,18 @@ 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 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
+    - 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
@@ -1793,6 +1851,10 @@ view would leave a wallet one click from deletion.
       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,
@@ -1810,7 +1872,7 @@ view would leave a wallet one click from deletion.
     - "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 the errors box, no screen change. After a switch,
+      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
@@ -1824,13 +1886,21 @@ view would leave a wallet one click from deletion.
       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**
@@ -1850,14 +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 →
@@ -1878,9 +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**
@@ -1900,6 +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**
@@ -1922,7 +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
@@ -1930,7 +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
@@ -2323,19 +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, and unless a swap pays only the From address, a
-      `Paid to` line for each other address it pays, or saying that its output
-      stays in the router or who it pays is unknown (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
@@ -2944,24 +3039,56 @@ Currently supported:
   "Swap USDT → ETH"), token addresses, amounts, execution steps, and deadline.
   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 active network. 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 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 by its command type,
-  which the decoder reads from the command byte with the mask the router at that
-  address uses: `0x1f` for `UniversalRouterV1`, `0x3f` for
+  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 a step's name. 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
+  (`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`
@@ -2973,40 +3100,173 @@ Currently supported:
   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. When a swap
-  step, `TAKE` or `TAKE_PORTION` pays the router the swap's output token, the
-  output stays in the router unless a later step pays all the router holds of it
-  to anyone but the router: a `SWEEP` of that token, an `UNWRAP_WETH` when it is
-  WETH, or a `TRANSFER` of `CONTRACT_BALANCE`, a `PAY_PORTION` of 10,000 bips or
-  a `PAY_PORTION_FULL_PRECISION` of 1e18 of that token. 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), no step
-  pays any other address, no step that may pay an address went unread, and the
-  output does not stay in the router. Otherwise it reads `Min. paid out`, a
-  `Paid to` line after `Token Out` names each other address paid, one reads
-  `The router, where it stays (no later step pays it out)` when the output stays
-  in the router, and one more reads `Unknown (could not be decoded)` when such a
-  step went unread, or `Unknown (not named in the calldata)` when no step pays
-  anyone. A step goes unread when its recipient does not decode as an address,
-  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`, `V4_SWAP`, `SWEEP`, `TRANSFER`,
-  `PAY_PORTION`, `PAY_PORTION_FULL_PRECISION`, `WRAP_ETH`, `UNWRAP_WETH` and
-  `BALANCE_CHECK_ERC20` (`V3_SWAP_EXACT_OUT`, `PERMIT2_TRANSFER_FROM_BATCH`,
-  `EXECUTE_SUB_PLAN` and `ACROSS_V4_DEPOSIT_V3` among them).
+  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
 

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/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/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">
@@ -697,6 +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

src/popup/index.js

@@ -220,7 +220,7 @@ async function widenApprovalWindow() {
 async function init() {
     // First, before anything can save: showView() saves on every navigation
     // without awaiting, so a save that fails from here on has somewhere to be
-    // reported rather than being swallowed by the save queue
+    // reported rather than reaching only the console
     // (https://git.eeqj.de/sneak/AutistMask/issues/362). Registered ahead of
     // the approval-window branch below too, since that window saves as well.
     //

src/popup/viewRouter.js

@@ -127,28 +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(). `chainId`, which
-// show() fills in when it is absent, picks the network whose explorer the
-// address links open, so it has to name one.
+// 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) &&
+        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)
     );
 }
 
@@ -200,11 +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:

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
@@ -85,13 +92,12 @@ function tokenAmountText(rawAmount, decimals, symbol) {
 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 {
@@ -225,10 +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 =
@@ -261,10 +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 = {
@@ -341,27 +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
@@ -388,9 +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

@@ -23,12 +23,10 @@ const {
     goBack,
     onViewLeave,
     formatFee,
+    reviewedNetworkProvider,
 } = require("./helpers");
 const { state, currentNetwork } = require("../../shared/state");
-const {
-    networkByChainId,
-    nativeCurrencyByChainId,
-} = require("../../shared/networks");
+const { nativeCurrencyByChainId } = require("../../shared/networks");
 const { getSignerForAddress } = require("../../shared/wallet");
 const { walletDefect } = require("../../shared/walletDefects");
 const { decryptWithPassword } = require("../../shared/vault");
@@ -45,8 +43,8 @@ const {
     transferAmountUnits,
 } = require("../../shared/transferAmount");
 const { assertWithinCeilings } = require("../../shared/approvalVerify");
-// The balance line and the fee reserve 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,
@@ -100,8 +98,32 @@ 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
@@ -110,7 +132,7 @@ function renderAmount(txInfo) {
     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,
     );
 }
@@ -291,9 +313,13 @@ function show(txInfo) {
 
     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";
@@ -430,20 +456,6 @@ function setVisible(id, visible) {
     $(id).style.visibility = visible ? "visible" : "hidden";
 }
 
-// The node of the network this transaction was reviewed for, which need not be
-// the active one: the popup can reopen onto this screen after Settings switched
-// the network. Its RPC URL is the one Settings has for that network: the
-// active network's is state.rpcUrl, any other's the one remembered for it (see
-// applyChainSwitchFields()).
-function reviewedNetworkProvider(txInfo) {
-    const net = networkByChainId(txInfo.chainId);
-    if (net.id === state.networkId) {
-        return getProvider(state.rpcUrl, net.id);
-    }
-    const remembered = state.networkEndpoints[net.id] || {};
-    return getProvider(remembered.rpcUrl || net.defaultRpcUrl, net.id);
-}
-
 async function estimateGas(txInfo) {
     try {
         const provider = reviewedNetworkProvider(txInfo);
@@ -556,16 +568,17 @@ async function estimateGas(txInfo) {
     }
 }
 
-// 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") {
@@ -593,15 +606,6 @@ 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 the invalid-amount message,
-// 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) {
     try {
         const provider = reviewedNetworkProvider(txInfo);
@@ -609,6 +613,9 @@ async function checkRecipientHistory(txInfo) {
             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";
@@ -637,6 +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.
@@ -651,11 +663,7 @@ function init(_ctx) {
         // 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;
         }
 
@@ -664,11 +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;
         }
 
@@ -700,6 +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);
@@ -716,19 +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/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
@@ -19,6 +22,7 @@ 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");
@@ -128,7 +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.
@@ -295,15 +300,30 @@ 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:
@@ -606,6 +626,30 @@ const EXT_ICON =
     `<path d="M7 1.5h3.5V5M7 5.5L10.5 1.5"/>` +
     `</svg></span>`;
 
+// 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,
+    };
+}
+
+// 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
@@ -746,6 +790,7 @@ module.exports = {
     keyMaterialName,
     unknownableAmount,
     nativeCurrency,
+    tokenSourcesByChainId,
     tokenLabel,
     formatFee,
     addressDotHtml,
@@ -761,6 +806,8 @@ module.exports = {
     attachCopyHandlers,
     etherscanLinkHtml,
     explorerUrl,
+    endpointsByChainId,
+    reviewedNetworkProvider,
     EXT_ICON,
     truncateMiddle,
     isoDate,

src/popup/views/settings.js

@@ -343,11 +343,13 @@ function init(ctx) {
         // switch request.
         notify({ type: "AUTISTMASK_NETWORK_CHANGED", chainId: net.chainId });
         resetRenderedViews();
-        // Settings itself is brought up to date for the new network here.
+        // 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/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 +141,11 @@ 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.
+        // A page in a Firefox private window is the exception: Firefox gives
+        // it locks of its own (README, "Stored state and its version").
+        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

@@ -18,10 +18,11 @@ const {
     copyableHtml,
     etherscanLinkHtml,
     explorerUrl,
+    endpointsByChainId,
     displaySymbol,
     goBack,
 } = require("./helpers");
-const { state, currentNetwork } = require("../../shared/state");
+const { state } = require("../../shared/state");
 const { nativeCurrencyByChainId } = require("../../shared/networks");
 const { formatEther, formatUnits } = require("ethers");
 const { log, debugFetch } = require("../../shared/log");
@@ -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();
@@ -316,12 +329,12 @@ 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.
-        // On the active network, the one whose explorer was just asked, and
-        // from the sender it reports.
+        // 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 || "",
-            currentNetwork().chainId,
+            chainId,
             txData.from?.hash || "",
         );
         if (decoded) {
@@ -340,9 +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/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/prices.js

@@ -38,11 +38,12 @@ function clearPrices() {
 }
 
 // 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 / unknown.
+// 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");
     const network = chainId ? networkByChainId(chainId) : currentNetwork();
-    if (network.isTestnet) return null;
+    if (!network || network.isTestnet) return null;
     return prices[symbol] || null;
 }
 

src/shared/state.js

@@ -35,7 +35,7 @@ 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
@@ -458,8 +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
@@ -529,35 +529,21 @@ async function saveStateOnce() {
     rawState.hasWallet = rawState.wallets.length > 0;
 
     // What this save compared and wrote, not the page's state now: a change
-    // made during the save must still differ from the baseline, or the save
-    // queued after it finds nothing to store
+    // made during the save must still differ from the baseline, or the next
+    // save finds nothing to store
     // (https://git.eeqj.de/sneak/AutistMask/issues/448).
     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
@@ -583,11 +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";

tests/addressKey.test.js

@@ -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/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/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

@@ -189,7 +189,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const {
     BaseWallet,
@@ -333,7 +333,7 @@ function expectNativeTransferOn(networkId) {
         "Native " + symbol + " transfer",
     );
     expect(el("confirm-amount").textContent).toBe(
-        "1 " + symbol + usdOn(networkId, "$2,000.00"),
+        "1.0000 " + symbol + usdOn(networkId, "$2,000.00"),
     );
     expect(el("confirm-balance").textContent).toBe(
         "5.0000 " + symbol + usdOn(networkId, "$10,000.00"),
@@ -440,12 +440,8 @@ 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);
         });
     },
 );
@@ -497,10 +493,7 @@ describe.each([
             expect(mockNode.broadcast).toEqual([]);
             expect(txStatus.showWait).not.toHaveBeenCalled();
             expect(txStatus.showError).not.toHaveBeenCalled();
-            expect(el("confirm-errors").innerHTML).toContain(
-                "The active network changed after this transaction was" +
-                    " reviewed, so it was not sent.",
-            );
+            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 () => {
@@ -579,10 +572,7 @@ describe.each([
 
             expect(signTransaction).not.toHaveBeenCalled();
             expect(mockNode.broadcast).toEqual([]);
-            expect(errors()).toContain(
-                "The active network changed after this transaction was" +
-                    " reviewed, so it was not sent.",
-            );
+            expect(shown("confirm-network-changed-error")).toBe(true);
         });
 
         const tokenSend = {
@@ -629,10 +619,7 @@ describe.each([
 
             expect(signTransaction).not.toHaveBeenCalled();
             expect(mockNode.broadcast).toEqual([]);
-            expect(errors()).toContain(
-                "The active network changed after this transaction was" +
-                    " reviewed, so it was not sent.",
-            );
+            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 () => {
@@ -662,7 +649,7 @@ describe.each([
                 `href="${explorerUrl}/address/${TOKEN}"`,
             );
             expect(el("confirm-amount").textContent).toBe(
-                "10 USDC" + usdOn(reviewedOn, "$10.00"),
+                "10.0000 USDC" + usdOn(reviewedOn, "$10.00"),
             );
             expect(el("confirm-balance").textContent).toBe(
                 "50.0000 USDC" + usdOn(reviewedOn, "$50.00"),

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/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: [],
     };
 }
@@ -481,7 +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
@@ -625,6 +626,8 @@ 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

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, how tall the whole view is, and where Sign & Send sits in it.
+// 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 +2310,9 @@ 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,
@@ -2262,6 +2330,12 @@ async function confirmState(page) {
             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,
         };
     });
@@ -2905,9 +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),
     );
@@ -3057,6 +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
@@ -3157,10 +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
@@ -4752,8 +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",

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);
     });
@@ -429,10 +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/persistedEntryFloors.test.js

@@ -364,7 +364,7 @@ describe("a save that fails", () => {
         return storage;
     }
 
-    test("is reported, not swallowed by the save queue", async () => {
+    test("is reported when the caller does not await it", async () => {
         const storage = failingStorage(unversionedValidProfile());
         const { state, loadState, saveState, onSaveFailure } =
             loadStateModule(storage);

tests/persistedFieldContract.test.js

@@ -441,6 +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" } },
@@ -454,6 +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"],
@@ -477,6 +508,19 @@ 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: {
@@ -799,7 +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,
@@ -808,7 +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

@@ -58,7 +58,7 @@ function restoringOnto(view, 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 },
+            tx: { hash: "0x1", from: ADDRESS, to: ADDRESS, chainId: "0x1" },
         }),
     );
 

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");

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/stateMerge.test.js

@@ -160,7 +160,7 @@ describe("the approval-window reproduction", () => {
         await approvalWindow.state.loadState();
         approvalWindow.helpers.showView("approve-tx");
         // showView() does not await its own saveState(); an extra save
-        // joins the same queue and only resolves once that one has too,
+        // waits for the lock behind that one and so resolves only after it,
         // which is the black-box way to know it landed.
         await approvalWindow.state.saveState();
 

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 +1,96 @@
+// 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 a 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 background and a page outside
+// a Firefox private window 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 +1,27 @@
+// `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 the extension's background and its pages share the browser's,
+// except a page in a Firefox private window (README, "Stored state and its
+// version").
+//
+// 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/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

@@ -313,9 +313,9 @@ describe("Back after a switch from the Settings gear", () => {
         boot.node("confirm-tx-password").value = "any password";
         await boot.click("btn-confirm-send");
         expect(boot.visibleViews()).toEqual(["confirm-tx"]);
-        expect(boot.node("confirm-errors").innerHTML).toContain(
-            "The active network changed after this transaction was reviewed",
-        );
+        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("");
     });

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

@@ -7,6 +7,12 @@
 // 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.
@@ -33,6 +39,7 @@ globalThis.chrome = {
 };
 
 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");
@@ -47,6 +54,8 @@ 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";
@@ -129,8 +138,13 @@ describe("execute() calldata on the approval screen's decoder", () => {
 // 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 },
@@ -186,19 +200,27 @@ function node(id) {
     return globalThis.document.getElementById(id);
 }
 
-// Open the transaction detail screen with Sepolia active, for the
-// transaction the explorer reports sent to `sentTo`, and wait for its
-// decoded details.
-async function showDetailSentTo(sentTo) {
-    mockSentTo = sentTo;
+// 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 = "sepolia";
+    state.networkId = activeNetworkId;
     state.blockscoutUrl = "https://explorer.example/api/v2";
     state.viewData = {};
     state.viewStack = [];
     state.currentView = null;
-    transactionDetail.show({
+    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,
@@ -210,33 +232,94 @@ async function showDetailSentTo(sentTo) {
             directionLabel: "Swap",
             method: "execute",
             chainId: SEPOLIA,
-    });
-    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+        },
+        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);
+        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);
+        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);
+        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) {

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, "0x1", {});
+    const decoded = decode(data);
     expect(decoded).not.toBeNull();
     return decoded.details.find((d) => d.label === label);
 }
@@ -113,9 +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, "0x1", {}).name).toBe(
-            "Uniswap Swap",
-        );
+        expect(decode(data()).name).toBe("Uniswap Swap");
     });
 });
 
@@ -125,9 +130,7 @@ 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, "0x1", {}).name).toBe(
-            "Uniswap Swap",
-        );
+        expect(decode(data()).name).toBe("Uniswap Swap");
     });
 
     test("still states the output it did establish", () => {
@@ -175,9 +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, "0x1", {}).name).toBe(
-            "Swap ETH → USDT",
-        );
+        expect(decode(data).name).toBe("Swap ETH → USDT");
     });
 
     test("WRAP_ETH is still ETH at 18 decimals", () => {

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");

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",