fix: a split swap's Min. received is the sum of its steps' minimums (closes #647)

The step that sets the output side gives the minimum. When that step
and earlier swap steps each pay the output token to the sender, the
minimum is now the sum of their minimums. There is no figure when the
decoder reads none from one of them, or when one of them pays part of
that token elsewhere.

These steps drop earlier steps from the sum:

- a V2 or V3 swap step that spends the output token;
- a V4 step with a swap action that spends that token, or with a SETTLE
  or SETTLE_ALL of that token;
- a PERMIT2_TRANSFER_FROM of that token.

A step after the step that sets the output side drops nothing from the
sum.

Model: opus-5-5

Dockerfile

@@ -10,6 +10,7 @@ WORKDIR /app
 
 COPY script/ script/
 COPY package.json yarn.lock ./
+# yarn warns about the workspaces field in eslint and babel-plugin-istanbul; no newer release drops it.
 RUN script/bootstrap
 
 COPY . .

README.md

@@ -905,8 +905,8 @@ src/
     prices.js         — ETH/USD and token/USD from Chainlink price feeds
     scamlist.js       — known fraud contract addresses
     state.js          — persisted state (extension storage)
-    storedSettings.js — "Use Blockscout" and "Check recipients on Etherscan",
-                        read from storage for the requests those settings gate
+    storedSettings.js — "Use Blockscout", "Check recipients on Etherscan" and
+                        the active network, read from storage
     symbolSpoof.js    — the known-symbol spoof rule, shared by all surfaces
     tokenList.js      — top ERC-20 tokens by market cap, and their Chainlink
                         price feeds (hardcoded)
@@ -1266,7 +1266,8 @@ see Transaction Decoding), do not always read as a number. They can read:
   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 or V3 exact-out step sets `Min. received`, that line shows
-  its `amountOut`, the exact amount it buys.
+  its `amountOut`, the exact amount it buys. When earlier swap steps also pay
+  that token to the user, the line shows the sum (see Transaction Decoding).
 - `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. Transaction Decoding
@@ -1277,22 +1278,18 @@ see Transaction Decoding), do not always read as a number. They can read:
   step pays nothing itself and swaps whatever an earlier step sent to the pair,
   so the calldata states no quantity. A V3 exact-in `amountIn` of zero has no
   such meaning and is shown as a zero.
-- `None (no minimum guaranteed)`: the swap's `Min. received` line, when the
-  minimum it shows is zero, whether a V2, V3 or V4 swap's minimum or a
-  `BALANCE_CHECK_ERC20` step's `minBalance`. Before
-  [#359](https://git.eeqj.de/sneak/AutistMask/issues/359), a zero `minBalance`
-  read `0.0000` when the token's scale was known. The router passes a balance
-  check whenever the balance is at least `minBalance`, so a zero `minBalance`
-  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. 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.
+- `None (no minimum guaranteed)`: the swap's `Min. received` line, when it shows
+  a V2, V3 or V4 swap's minimum of zero. The router passes a
+  `BALANCE_CHECK_ERC20` step whenever the balance is at least `minBalance`, so a
+  zero `minBalance` guarantees nothing. A check with a zero `minBalance` sets
+  neither `Token Out` nor `Min. received`. A nonzero `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
@@ -1477,21 +1474,20 @@ tracked.
 
 A tracked token is shown when its balance is nonzero, and any other ERC-20 when
 its balance is nonzero and it is in the bundled known-token list or has 1,000 or
-more holders. A token claiming a symbol from the bundled list from any other
-contract address is always dropped, tracked or not, and so is any token claiming
-a symbol that belongs to the native asset and therefore has no legitimate
-contract at all (`"ETH"`, and every network's `nativeCurrency`, such as
-`"SepoliaETH"`, on every network). That filter is unconditional — the "Hide
-tokens with fewer than 1,000 holders" setting governs the transaction history
-and the send-screen token selector, not this list. A token's holder count is
-unknown when the explorer reports none, or reports anything other than a whole
-number written in digits alone, such as `1,000` or `1e3` (`parseHoldersCount()`
-in `src/shared/holders.js`). This list does not take an unknown count as 1,000
-or more, so such a token is shown only when it is on the bundled list or
-tracked. Every nonzero holding of a token shown is stored exactly, however
-small, but a holding below 0.000001 is left out of the balance lists, the
-send-screen token selector, the address total and the remove-address warning
-(`isBelowOneMillionth()` in `src/shared/amountDisplay.js`). The Send and
+more holders. The balance list always drops a token that claims a bundled-list
+symbol from another contract address, whatever the settings. The list also drops
+every token that claims the native asset's symbol: `"ETH"`, or any network's
+`nativeCurrency`, such as `"SepoliaETH"`. That filter is unconditional — the
+"Hide tokens with fewer than 1,000 holders" setting governs the transaction
+history and the send-screen token selector, not this list. A token's holder
+count is unknown when the explorer reports none, or reports anything other than
+a whole number written in digits alone, such as `1,000` or `1e3`
+(`parseHoldersCount()` in `src/shared/holders.js`). This list does not take an
+unknown count as 1,000 or more, so such a token is shown only when it is on the
+bundled list or tracked. Every nonzero holding of a token shown is stored
+exactly, however small, but a holding below 0.000001 is left out of the balance
+lists, the send-screen token selector, the address total and the remove-address
+warning (`isBelowOneMillionth()` in `src/shared/amountDisplay.js`). The Send and
 confirmation screens show it when its token is the one being sent. Tracked
 tokens with a zero balance are listed as well while "Show tracked tokens with
 zero balance" is on.
@@ -2057,15 +2053,21 @@ 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" (correct password) when the gas limit or a fee is over its
+      bound → 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, no screen change. For
+      an ETH amount that Send's "Max" filled in, the gas limit and fees are
+      those of this screen's own fee estimate (see Amount above). For any other
+      send, the RPC endpoint fills in the gas limit and fees at signing. Just
+      before signing, `assertWithinCeilings()` (`src/shared/approvalVerify.js`)
+      refuses the send when any of these is over its bound:
+        - the gas limit
+        - each fee per gas the transaction sets
+        - the total fee: the gas limit times `maxFeePerGas`, or times `gasPrice`
+          when the transaction has no `maxFeePerGas`
+    - "Sign & Send" (wrong password) → "That password is incorrect. Please try
+      again." 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
@@ -2237,6 +2239,10 @@ view would leave a wallet one click from deletion.
       **AddressDetail**
     - "Add" with a token already tracked, a scam-listed address, or a failed
       contract lookup → flash message, no screen change
+    - "Add" with a token that the spoof rule refuses → nothing is tracked; "Not
+      added: this token fakes a known symbol." flash message, no screen change
+    - "Add", then the contract lookup answers while another screen shows, or
+      after AddToken was opened again → tracks the token, no screen change
     - "Add", then a network switch in Settings before the contract lookup
       answers → nothing is tracked; "The active network changed before the
       lookup finished, so the token was not added." flash message, no screen
@@ -2281,6 +2287,13 @@ view would leave a wallet one click from deletion.
         - Endpoint URL input + "Save" button. "Save" asks the URL for `/stats`
           and saves the URL only if that request succeeds. The request carries
           no user data and is made whether or not "Use Blockscout" is ticked.
+    - If the network changes before either "Save" stores its URL, the URL is not
+      saved and a flash message says so
+    - Either "Save" stores its URL only if the input still shows that URL when
+      the endpoint answers. Otherwise a flash message says that the URL was not
+      saved
+    - If the user taps the same "Save" again before the endpoint answers, the
+      earlier tap stores nothing and shows no flash message
     - Etherscan:
         - "Check recipients on Etherscan" checkbox, unticked until the user
           ticks it
@@ -2538,6 +2551,9 @@ view would leave a wallet one click from deletion.
       "Added SYMBOL" flash message (no screen change)
     - A duplicate, a scam-listed address, or a failed contract lookup → flash
       message, no screen change
+    - "Add" by contract address with a token that the spoof rule refuses →
+      nothing is tracked; "Not added: this token fakes a known symbol." flash
+      message, no screen change
     - "Add" by contract address, then a network switch in Settings before the
       lookup answers → nothing is tracked; "The active network changed before
       the lookup finished, so the token was not added." flash message, no screen
@@ -3395,7 +3411,8 @@ Currently supported:
   `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
+  as `Balance Check (could not be decoded)`. A check with a zero `minBalance`
+  sets neither `Token Out` nor the minimum. 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
@@ -3460,136 +3477,160 @@ Currently supported:
   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
+  minimum reads `Min. paid out`. The step that sets the output side gives the
+  minimum. When that step and earlier swap steps each pay the output token to
+  the transaction's sender, the minimum is the sum of their minimums. There is
+  no minimum when the decoder reads none from one of them, or when one of them
+  pays part of that token elsewhere. There is also no minimum when the decoder
+  did not read one of them, or a step between them, in full. A swap step that
+  spends the output token drops earlier steps from the sum. A V4 step spends
+  each token that its swap actions spend. A V4 `SETTLE` or `SETTLE_ALL` of the
+  output token also drops earlier steps. A `PERMIT2_TRANSFER_FROM` of the output
+  token drops earlier steps too. A step after the step that sets the output side
+  drops nothing from the sum. 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. A `PERMIT2_PERMIT` names `Token In` only when its amount,
-  `Unlimited` included, stands as the `Amount` figure in place of the total,
-  which it does only in the plain shape of Uniswap's own routes: it comes before
-  the step that sets the input side, it is the only `PERMIT2_PERMIT` in the
-  transaction and there is no `PERMIT2_PERMIT_BATCH`, its spender is the router,
-  the router may not let it fail, no step before it takes its token, a
-  `PERMIT2_TRANSFER_FROM` of it included, 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 before the permit takes under whatever allowance the router
-  already had, so it may take more than the permit's amount, which would then
-  read lower than what leaves the user's wallet: a `PERMIT2_TRANSFER_FROM` of
-  2,000 USDT into the router, then a permit of 600 USDT to the router and a V3
-  exact-in of 2,000 USDT paid from the router, read `Amount 2000.0000 USDT`. A
-  later permit or batch may raise what Permit2 lets the router take, and so may
-  a step the decoder does not read in full: 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. Every other `PERMIT2_PERMIT`, before
-  the step that sets the input side or after it, leaves `Token In` and the
-  `Amount` line as they read with no permit, unless it lets a spender other than
-  the router take `Token In` (see below): a permit of 5,000 DAI to another
-  address and then a V3 exact-in of 600 USDT read `Swap USDT → USDC` with
-  `Amount 600.0000 USDT`, and so do that exact-in and then a permit of 5,000 DAI
-  to the router. When a permit's amount stands and the step that sets the input
-  side spends a token other than the permit's, or one the decoder does not know,
-  that step's amount gets lines of its own, unless it states no amount and the
-  user pays it none of its input token. 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 there is no `Amount` line, each
-  take the total counts gets them too, so that every amount the decoder reads is
-  shown: the amount the step that sets the input side states, when it is a
-  quantity and the user pays that step (a V2 or V3 step whose `payerIsUser` is
-  true, a V4 step the user pays some of its input token, or a `WRAP_ETH`, whose
-  ETH comes from the transaction's value), and each later take of `Token In`
-  added to it. A step that sets the input side and is paid from the router takes
-  nothing from the user's wallet and gets none. A `PERMIT2_PERMIT` the decoder
-  cannot read, then V3 exact-ins of 600 USDT and 400 DAI paid by the user, give
-  lines for both amounts. 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,
-  except that the step that sets the input side comes first when it has them,
-  followed, when there is no `Amount` line, by the other takes the total counts:
-  `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
+  rest taken to another address, reads `5000.0000 USDT`. A later step that pays
+  an ERC-20 token from the router takes none of that token from the user's
+  wallet. A V2 exact-in whose `amountIn` is `ALREADY_PAID` takes nothing either.
+  A V4 `SETTLE` of ETH paid from the router still takes from the user's wallet,
+  since the router holds the transaction's value. When the decoder does not know
+  the amount of such a `SETTLE`, as for `CONTRACT_BALANCE`, that `SETTLE` counts
+  as a later step's take. When an earlier step left ETH in the router, that ETH
+  may pay part of a `SETTLE` of ETH paid from the router. That `SETTLE` then
+  gets lines of its own, with `Up to` before its amount. A later take of
+  `Token In` that only the user's wallet pays 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. A
+  `PERMIT2_PERMIT` names `Token In` only when its amount, `Unlimited` included,
+  stands as the `Amount` figure in place of the total, which it does only in the
+  plain shape of Uniswap's own routes: it comes before the step that sets the
+  input side, it is the only `PERMIT2_PERMIT` in the transaction and there is no
+  `PERMIT2_PERMIT_BATCH`, its spender is the router, the router may not let it
+  fail, no step before it takes its token, a `PERMIT2_TRANSFER_FROM` of it
+  included, 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 before the
+  permit takes under whatever allowance the router already had, so it may take
+  more than the permit's amount, which would then read lower than what leaves
+  the user's wallet: a `PERMIT2_TRANSFER_FROM` of 2,000 USDT into the router,
+  then a permit of 600 USDT to the router and a V3 exact-in of 2,000 USDT paid
+  from the router, read `Amount 2000.0000 USDT`. A later permit or batch may
+  raise what Permit2 lets the router take, and so may a step the decoder does
+  not read in full: 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. Every other `PERMIT2_PERMIT`, before the step that sets the
+  input side or after it, leaves `Token In` and the `Amount` line as they read
+  with no permit, unless it lets a spender other than the router take `Token In`
+  (see below): a permit of 5,000 DAI to another address and then a V3 exact-in
+  of 600 USDT read `Swap USDT → USDC` with `Amount 600.0000 USDT`, and so do
+  that exact-in and then a permit of 5,000 DAI to the router. A permit on the
+  zero address never stands as the `Amount` figure, because Permit2 has no
+  allowance of ETH. When a permit's amount stands and the step that sets the
+  input side spends a token other than the permit's, or one the decoder does not
+  know, that step's amount gets lines of its own, unless it states no amount and
+  the user pays it none of its input token. 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);
+  an ETH take whose line reads `Up to` (see above); and one whose amount the
+  decoder does not know. When there is no `Amount` line, each take the total
+  counts gets them too, so that every amount the decoder reads is shown: the
+  amount the step that sets the input side states, when it is a quantity and the
+  user pays that step (a V2 or V3 step whose `payerIsUser` is true, a V4 step
+  the user pays some of its input token, or a `WRAP_ETH`, whose ETH comes from
+  the transaction's value), and each later take of `Token In` added to it. A
+  step that sets the input side gets none when the user pays it none of its
+  input token. A `PERMIT2_PERMIT` the decoder cannot read, then V3 exact-ins of
+  600 USDT and 400 DAI paid by the user, give lines for both amounts. 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, that step never gets them, with a permit
+  or without. They come in step order, except that the step that sets the input
+  side comes first when it has them, followed, when there is no `Amount` line,
+  by the other takes the total counts: `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. Every `PERMIT2_PERMIT` whose
-  amount does not stand as the `Amount` figure, before the step that sets the
-  input side or after it, gives three lines, in step order, after those for each
-  `PERMIT2_TRANSFER_FROM`: `Permit2 allowance`, its amount, for example
+  where it goes, and so its amount is shown once. For a move of the zero
+  address, `Moved from the sender` gives the amount in base units and
+  `Token moved` gives the zero address. For such a move into the router, the
+  `Paid to` line gives the amount in base units and
+  `Token moved into the router` gives the zero address. Every `PERMIT2_PERMIT`
+  whose amount does not stand as the `Amount` figure, before the step that sets
+  the input side or after it, gives three lines, in step order, after those for
+  each `PERMIT2_TRANSFER_FROM`: `Permit2 allowance`, its amount, for example
   `5000.0000 DAI`, or `Unlimited` for Permit2's maximum; `Allowance token`,
   giving the token's address as the `Token In` line does; and
   `Allowance spender`, the address it lets take the token. Only a permit whose
   amount stands gives none: the `Amount` line gives its amount, `Token In` its
   token, and its spender is the router. Each allowance a `PERMIT2_PERMIT_BATCH`
   grants, one for each token it names, all for its one spender, gives the same
-  three lines, in step order with those of each `PERMIT2_PERMIT`. A
-  `PERMIT2_PERMIT` or `PERMIT2_PERMIT_BATCH` whose input the decoder cannot
-  read, such as one whose token or spender word has a nonzero top byte, may let
-  any spender take any amount of any token: it gives one `Permit2 allowance`
-  line alone, reading `Unknown (could not be decoded)`. These lines change no
-  `Paid to` line: a permit or batch pays nobody. But code that a step runs, such
-  as a V4 pool's hook or a token's own code, can call a spender other than the
-  router, which can then take up to its allowance from the user's wallet before
-  the transaction ends. So an allowance to any spender but the router, or a
-  permit or batch the decoder cannot read, makes the minimum read
-  `Min. paid out`, and when its token is `Token In`, or the decoder does not
-  know its token or `Token In`, it leaves no `Amount` line, whose figure might
-  be too low: a permit of 5,000 USDT to another address and then a V3 exact-in
-  of 600 USDT read with no `Amount` line, and the 600 USDT gets lines of its
-  own. 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_PERMIT_BATCH`,
-  `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.
+  three lines, in step order with those of each `PERMIT2_PERMIT`. For an
+  allowance of the zero address, `Permit2 allowance` gives the amount in base
+  units and `Allowance token` gives the zero address. A `PERMIT2_PERMIT` or
+  `PERMIT2_PERMIT_BATCH` whose input the decoder cannot read, such as one whose
+  token or spender word has a nonzero top byte, may let any spender take any
+  amount of any token: it gives one `Permit2 allowance` line alone, reading
+  `Unknown (could not be decoded)`. These lines change no `Paid to` line: a
+  permit or batch pays nobody. But code that a step runs, such as a V4 pool's
+  hook or a token's own code, can call a spender other than the router, which
+  can then take up to its allowance from the user's wallet before the
+  transaction ends. So an allowance to any spender but the router, or a permit
+  or batch the decoder cannot read, makes the minimum read `Min. paid out`, and
+  when its token is `Token In`, or the decoder does not know its token or
+  `Token In`, it leaves no `Amount` line, whose figure might be too low: a
+  permit of 5,000 USDT to another address and then a V3 exact-in of 600 USDT
+  read with no `Amount` line, and the 600 USDT gets lines of its own. 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_PERMIT_BATCH`, `PERMIT2_TRANSFER_FROM`,
+  `V2_SWAP_EXACT_IN`, `V2_SWAP_EXACT_OUT`, `V3_SWAP_EXACT_IN`,
+  `V3_SWAP_EXACT_OUT`, `V4_SWAP`, `SWEEP`, `TRANSFER`, `PAY_PORTION`,
+  `PAY_PORTION_FULL_PRECISION`, `ACROSS_V4_DEPOSIT_V3`, `WRAP_ETH`,
+  `UNWRAP_WETH` and `BALANCE_CHECK_ERC20` (`PERMIT2_TRANSFER_FROM_BATCH`,
+  `EXECUTE_SUB_PLAN` and the NFT commands among them), or a type its release
+  names no command for.
 
 ### Non-Goals Forever
 

docs/README.md

@@ -380,10 +380,8 @@ but comes from an unrecognized contract, it is identified as a spoof and hidden.
 In your transaction history this is the "Hide fake tokens impersonating a known
 symbol" setting, which you can switch off; doing so also stops new entries being
 added to the fraud contract blocklist below, since detecting a spoof is what
-fills it. The send token list always applies the check. Your balances apply it
-too, with one exception: a token claiming the symbol "ETH" is not filtered
-there, so a fake "ETH" token can still show up in your balance list even though
-it is hidden from your transaction history and from the send token list.
+fills it. The send token list always applies the check. Your balance list always
+applies the check too.
 
 **Low-holder token filtering.** Tokens with fewer than 1,000 holders are hidden
 from transaction history and the send token list, and are left out of your

eslint.config.js

@@ -153,8 +153,7 @@ module.exports = [
         },
     },
 
-    // The helpers the script/ entrypoints call: plain node programs too, run
-    // from a shell script rather than from yarn, and never bundled.
+    // The files in script/lib/ run on plain node too, and are never bundled.
     {
         files: ["script/lib/**/*.js"],
         languageOptions: {

package.json

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

script/bootstrap

@@ -118,6 +118,7 @@ ensure_yarn() {
     fi
 }
 
+# yarn warns about the workspaces field in eslint and babel-plugin-istanbul; no newer release drops it.
 install_js_deps() {
     if missing yarn && [ -s "$HOME/.nvm/nvm.sh" ]; then
         nvm_sh "nvm use $NODE_VERSION >/dev/null && cd \"$ROOT\" && \

script/lib/jest.js

@@ -0,0 +1,40 @@
+// Runs jest with the arguments it is given, and fails the run when jest had to
+// force-stop the worker process that ran a test file. Jest itself only prints a
+// warning when that happens, and its run still passes. The warning means a test
+// left a timer or another open handle running. The test scripts in package.json
+// run jest through this file.
+//
+// Jest runs inside this process and writes to the terminal directly, so its
+// output looks the same as a plain jest run. This file only checks each write
+// to stderr for the warning below.
+
+"use strict";
+
+// The start of the warning that jest prints on stderr after it force-stops a
+// worker process.
+const WORKER_WARNING = "A worker process has failed to exit gracefully";
+
+let forceStopped = false;
+
+const writeStderr = process.stderr.write.bind(process.stderr);
+process.stderr.write = (chunk, ...rest) => {
+    if (String(chunk).includes(WORKER_WARNING)) {
+        forceStopped = true;
+    }
+    return writeStderr(chunk, ...rest);
+};
+
+// Runs after jest has finished, as the process exits.
+process.on("exit", () => {
+    if (forceStopped) {
+        console.error(
+            "script/lib/jest.js: failing the run, because jest force-stopped " +
+                "a worker process. A test left a timer or another open " +
+                "handle running.",
+        );
+        process.exitCode = 1;
+    }
+});
+
+// Jest's own command-line program. It reads its arguments from process.argv.
+require("jest/bin/jest");

src/popup/index.js

@@ -65,7 +65,14 @@ function renderWalletList() {
 const pageClosed = new AbortController();
 window.addEventListener("pagehide", () => pageClosed.abort());
 
+// While a refresh runs, a request through ctx is not dropped. The request sets
+// refreshAgain, and one more refresh runs once the running one ends. Several
+// requests in that time lead to one more refresh, not several. An import asks
+// for a refresh after its address scan. A refresh already running does not
+// have the addresses the scan found
+// (https://git.eeqj.de/sneak/AutistMask/issues/581).
 let refreshInFlight = false;
+let refreshAgain = false;
 
 // The ten-second refresh startRefresh() starts, stopped when the popup moves to
 // the recovery screen: there is no profile left to refresh.
@@ -89,7 +96,10 @@ let refreshTimer = null;
 // user turned "Use Blockscout" off. So the save drops every token the user has
 // not tracked if the stored setting is off by then.
 async function doRefreshAndRender() {
-    if (refreshInFlight) return;
+    if (refreshInFlight) {
+        refreshAgain = true;
+        return;
+    }
     refreshInFlight = true;
     try {
         await followStoredSettings();
@@ -132,28 +142,35 @@ async function doRefreshAndRender() {
         });
         renderWalletList();
     } catch (e) {
-        // Every call site fires this and walks away — the boot below, the ten
-        // second interval, and eight views through ctx — so it must never
-        // reject: an unhandled rejection is not a report of anything. The save
-        // inside it reports its own failure through onSaveFailure() (see
-        // src/shared/state.js); what is left here is a failed network round
-        // trip, which the next tick retries.
+        // No caller waits for this function, so it must never reject. An
+        // unhandled rejection reports nothing. The save inside it reports its
+        // own failure through onSaveFailure() (see src/shared/state.js); what
+        // is left here is a failed network round trip, which the next tick
+        // retries.
         log.errorf("popup: background refresh failed:", e);
     } finally {
         refreshInFlight = false;
     }
+    if (refreshAgain) {
+        refreshAgain = false;
+        doRefreshAndRender();
+    }
 }
 
 // Refreshes now and every ten seconds from then on. Called once a wallet
 // exists: by init() when the popup opens with one, and by AddWallet when it
 // adds one, which in a popup that opened on Welcome is the first
-// (https://git.eeqj.de/sneak/AutistMask/issues/530). With the refresh already
-// running it starts no second one, and on the recovery screen it does nothing.
+// (https://git.eeqj.de/sneak/AutistMask/issues/530). With the ten-second
+// refresh already started, it starts no second one. On the recovery screen it
+// does nothing.
 function startRefresh() {
     if (!$("view-state-recovery").classList.contains("hidden")) return;
     doRefreshAndRender();
     if (refreshTimer === null) {
-        refreshTimer = setInterval(doRefreshAndRender, 10000);
+        // A tick that finds a refresh running is dropped.
+        refreshTimer = setInterval(() => {
+            if (!refreshInFlight) return doRefreshAndRender();
+        }, 10000);
     }
 }
 

src/popup/views/addToken.js

@@ -3,9 +3,15 @@ const { getTopTokens } = require("../../shared/tokenList");
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const { lookupTokenInfo } = require("../../shared/balances");
 const { isScamAddress } = require("../../shared/scamlist");
+const { isSpoofedSymbol } = require("../../shared/symbolSpoof");
 const { log } = require("../../shared/log");
 
+// Counts the times AddToken has opened. A contract lookup started before
+// AddToken was last opened changes neither the screen nor the status line.
+let addTokenScreenOpenings = 0;
+
 function show() {
+    addTokenScreenOpenings++;
     $("add-token-address").value = "";
     $("add-token-info").textContent = "";
     $("add-token-info").style.visibility = "hidden";
@@ -55,6 +61,7 @@ function init(ctx) {
         // The network the lookup asks, which Settings may switch away from
         // before it answers, as for a transaction in confirmTx.js.
         const chainId = currentNetwork().chainId;
+        const opening = addTokenScreenOpenings;
         try {
             const info = await lookupTokenInfo(
                 contractAddr,
@@ -71,6 +78,15 @@ function init(ctx) {
                 );
                 return;
             }
+            // The balance list never shows a token that the spoof rule
+            // refuses, so such a token is not tracked.
+            if (isSpoofedSymbol(info.symbol, contractAddr)) {
+                showFlash("Not added: this token fakes a known symbol.");
+                if (addTokenScreenOpenings !== opening) return;
+                infoEl.textContent = "";
+                infoEl.style.visibility = "hidden";
+                return;
+            }
             log.infof("Adding token", info.symbol, contractAddr);
             state.trackedTokens.push({
                 address: contractAddr,
@@ -80,6 +96,17 @@ function init(ctx) {
             });
             await saveState();
             ctx.doRefreshAndRender();
+            // If the lookup answers after AddToken was opened again, the
+            // token is still added, but the screen and the status line stay
+            // as they are.
+            if (addTokenScreenOpenings !== opening) return;
+            // The lookup is over, so a later Back onto AddToken shows no
+            // status.
+            infoEl.textContent = "";
+            infoEl.style.visibility = "hidden";
+            // If the lookup answers while another screen shows, the token is
+            // still added but the screen does not change.
+            if (state.currentView !== "add-token") return;
             // Pop the stack (back to address detail) and re-render it
             // so the newly added token is visible immediately.
             if (state.viewStack.length > 0) {
@@ -100,6 +127,7 @@ function init(ctx) {
                     ? detail
                     : "Could not add the token.",
             );
+            if (addTokenScreenOpenings !== opening) return;
             infoEl.textContent = "";
             infoEl.style.visibility = "hidden";
         }

src/popup/views/addressDetail.js

@@ -22,6 +22,7 @@ const {
     filterTransactions,
 } = require("../../shared/transactions");
 const { resolveEnsNames } = require("../../shared/ens");
+const { storedNetworkIs } = require("../../shared/storedSettings");
 const {
     updateSendBalance,
     renderSendTokenSelect,
@@ -98,6 +99,7 @@ let loadedTxs = [];
 let ensNameMap = new Map();
 
 async function loadTransactions(address) {
+    const networkId = state.networkId;
     try {
         const rawTxs = await fetchRecentTransactions(
             address,
@@ -114,43 +116,74 @@ async function loadTransactions(address) {
         });
         const txs = result.transactions;
 
-        // Persist any newly discovered fraud contracts
-        if (result.newFraudContracts.length > 0) {
-            for (const addr of result.newFraudContracts) {
-                if (!state.fraudContracts.includes(addr)) {
-                    state.fraudContracts.push(addr);
-                }
-            }
-            await saveState();
-        }
-
-        loadedTxs = txs;
-
         // Collect ALL unique addresses (from + to) for ENS resolution so
         // that reverse lookups work for every displayed address, not just
         // the ones that were originally entered as ENS names.
         const counterparties = [
             ...new Set(txs.flatMap((tx) => [tx.from, tx.to].filter(Boolean))),
         ];
+        let names = new Map();
         if (counterparties.length > 0) {
             try {
-                ensNameMap = await resolveEnsNames(
+                names = await resolveEnsNames(
                     counterparties,
                     state.rpcUrl,
                     state.networkId,
                     ctx.pageClosed,
                 );
             } catch {
-                ensNameMap = new Map();
+                // The rows then show no ENS names.
             }
         }
 
+        // If the network changed during the lookups above, or the screen now
+        // shows another address, nothing is saved or drawn. See
+        // src/shared/storedSettings.js.
+        if (
+            state.networkId !== networkId ||
+            !(await storedNetworkIs(networkId)) ||
+            $("address-line").dataset.full !== address
+        ) {
+            return;
+        }
+
+        // Persist any newly discovered fraud contracts, inside the save and
+        // holding the lock. Nothing is added unless this page and the stored
+        // record both still name the request's network.
+        if (result.newFraudContracts.length > 0) {
+            let saved = false;
+            await saveState((stored) => {
+                if (state.networkId !== networkId) return false;
+                if (stored.networkId !== networkId) return false;
+                for (const addr of result.newFraudContracts) {
+                    if (!state.fraudContracts.includes(addr)) {
+                        state.fraudContracts.push(addr);
+                    }
+                }
+                saved = true;
+            });
+            // If the network changed while the save waited for the lock,
+            // nothing is drawn.
+            if (!saved) return;
+        }
+
+        loadedTxs = txs;
+        ensNameMap = names;
         renderTransactions(txs);
     } catch (e) {
         // Cancelled by the popup closing, not failed: see pageClosed in
         // src/popup/index.js.
         if (ctx.pageClosed.aborted) return;
         log.errorf("loadTransactions failed:", e.message);
+        // If the network changed, or the screen now shows another address,
+        // the failure is not shown.
+        if (
+            state.networkId !== networkId ||
+            !(await storedNetworkIs(networkId)) ||
+            $("address-line").dataset.full !== address
+        ) {
+            return;
+        }
         $("tx-list").innerHTML =
             '<div class="text-muted text-xs py-1">Failed to load transactions.</div>';
     }

src/popup/views/addressToken.js

@@ -29,6 +29,7 @@ const {
     filterTransactions,
 } = require("../../shared/transactions");
 const { resolveEnsNames } = require("../../shared/ens");
+const { storedNetworkIs } = require("../../shared/storedSettings");
 const {
     updateSendBalance,
     renderSendTokenSelect,
@@ -170,6 +171,7 @@ function show() {
 }
 
 async function loadTransactions(address, tokenId) {
+    const networkId = state.networkId;
     try {
         const rawTxs = await fetchRecentTransactions(
             address,
@@ -186,16 +188,6 @@ async function loadTransactions(address, tokenId) {
         });
         let txs = result.transactions;
 
-        // Persist any newly discovered fraud contracts
-        if (result.newFraudContracts.length > 0) {
-            for (const addr of result.newFraudContracts) {
-                if (!state.fraudContracts.includes(addr)) {
-                    state.fraudContracts.push(addr);
-                }
-            }
-            await saveState();
-        }
-
         // Filter to this token only
         if (tokenId === "ETH") {
             txs = txs.filter((tx) => tx.contractAddress === null);
@@ -207,32 +199,75 @@ async function loadTransactions(address, tokenId) {
             );
         }
 
-        loadedTxs = txs;
-
         // Collect ALL unique addresses for ENS resolution so reverse
         // lookups work for every displayed address.
         const counterparties = [
             ...new Set(txs.flatMap((tx) => [tx.from, tx.to].filter(Boolean))),
         ];
+        let names = new Map();
         if (counterparties.length > 0) {
             try {
-                ensNameMap = await resolveEnsNames(
+                names = await resolveEnsNames(
                     counterparties,
                     state.rpcUrl,
                     state.networkId,
                     ctx.pageClosed,
                 );
             } catch {
-                ensNameMap = new Map();
+                // The rows then show no ENS names.
             }
         }
 
+        // If the network changed during the lookups above, or the screen now
+        // shows another address or token, nothing is saved or drawn. See
+        // src/shared/storedSettings.js.
+        if (
+            state.networkId !== networkId ||
+            !(await storedNetworkIs(networkId)) ||
+            $("address-token-line").dataset.full !== address ||
+            state.selectedToken !== tokenId
+        ) {
+            return;
+        }
+
+        // Persist any newly discovered fraud contracts, inside the save and
+        // holding the lock. Nothing is added unless this page and the stored
+        // record both still name the request's network.
+        if (result.newFraudContracts.length > 0) {
+            let saved = false;
+            await saveState((stored) => {
+                if (state.networkId !== networkId) return false;
+                if (stored.networkId !== networkId) return false;
+                for (const addr of result.newFraudContracts) {
+                    if (!state.fraudContracts.includes(addr)) {
+                        state.fraudContracts.push(addr);
+                    }
+                }
+                saved = true;
+            });
+            // If the network changed while the save waited for the lock,
+            // nothing is drawn.
+            if (!saved) return;
+        }
+
+        loadedTxs = txs;
+        ensNameMap = names;
         renderTransactions(txs);
     } catch (e) {
         // Cancelled by the popup closing, not failed: see pageClosed in
         // src/popup/index.js.
         if (ctx.pageClosed.aborted) return;
         log.errorf("loadTransactions failed:", e.message);
+        // If the network changed, or the screen now shows another address or
+        // token, the failure is not shown.
+        if (
+            state.networkId !== networkId ||
+            !(await storedNetworkIs(networkId)) ||
+            $("address-token-line").dataset.full !== address ||
+            state.selectedToken !== tokenId
+        ) {
+            return;
+        }
         $("address-token-tx-list").innerHTML =
             '<div class="text-muted text-xs py-1">Failed to load transactions.</div>';
     }

src/popup/views/helpers.js

@@ -33,6 +33,7 @@ const { networkByChainId } = require("../../shared/networks");
 const { formatUsd, getPrice } = require("../../shared/prices");
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const { displaySymbol } = require("../../shared/symbolDisplay");
+const { isSpoofedSymbol } = require("../../shared/symbolSpoof");
 const { walletHasRecoveryPhrase } = require("../../shared/wallet");
 const { markViewRendered } = require("../viewRouter");
 
@@ -447,6 +448,9 @@ function balanceLinesForAddress(addr, trackedTokens, showZero) {
     if (showZero && trackedTokens) {
         for (const t of trackedTokens) {
             if (seen.has(t.address.toLowerCase())) continue;
+            // A token that the spoof rule refuses has no stored balance, and
+            // gets no zero row either.
+            if (isSpoofedSymbol(t.symbol, t.address)) continue;
             html += balanceLine(
                 t.symbol,
                 0,

src/popup/views/home.js

@@ -44,6 +44,7 @@ const {
     fetchRecentTransactions,
     filterTransactions,
 } = require("../../shared/transactions");
+const { storedNetworkIs } = require("../../shared/storedSettings");
 const { log } = require("../../shared/log");
 
 function findActiveAddr() {
@@ -183,6 +184,7 @@ async function loadHomeTxs(ctx) {
     }
     if (allAddresses.length === 0) return;
 
+    const networkId = state.networkId;
     const filters = {
         hideSpoofedSymbols: state.hideSpoofedSymbols,
         hideLowHolderTokens: state.hideLowHolderTokens,
@@ -202,6 +204,15 @@ async function loadHomeTxs(ctx) {
         );
         const results = await Promise.all(fetches);
 
+        // If the network changed during the lookups, nothing is saved or
+        // drawn. See src/shared/storedSettings.js.
+        if (
+            state.networkId !== networkId ||
+            !(await storedNetworkIs(networkId))
+        ) {
+            return;
+        }
+
         // Merge, deduplicate by hash, filter, sort, take 25
         const seen = new Set();
         let merged = [];
@@ -215,14 +226,24 @@ async function loadHomeTxs(ctx) {
 
         const filtered = filterTransactions(merged, filters);
 
-        // Persist any newly discovered fraud contracts
+        // Persist any newly discovered fraud contracts, inside the save and
+        // holding the lock. Nothing is added unless this page and the stored
+        // record both still name the request's network.
         if (filtered.newFraudContracts.length > 0) {
-            for (const addr of filtered.newFraudContracts) {
-                if (!state.fraudContracts.includes(addr)) {
-                    state.fraudContracts.push(addr);
+            let saved = false;
+            await saveState((stored) => {
+                if (state.networkId !== networkId) return false;
+                if (stored.networkId !== networkId) return false;
+                for (const addr of filtered.newFraudContracts) {
+                    if (!state.fraudContracts.includes(addr)) {
+                        state.fraudContracts.push(addr);
+                    }
                 }
-            }
-            await saveState();
+                saved = true;
+            });
+            // If the network changed while the save waited for the lock,
+            // nothing is drawn.
+            if (!saved) return;
         }
 
         merged = filtered.transactions;
@@ -234,6 +255,13 @@ async function loadHomeTxs(ctx) {
         // src/popup/index.js.
         if (ctx.pageClosed.aborted) return;
         log.errorf("loadHomeTxs failed:", e.message);
+        // If the network changed, the failure is not shown.
+        if (
+            state.networkId !== networkId ||
+            !(await storedNetworkIs(networkId))
+        ) {
+            return;
+        }
         const list = $("home-tx-list");
         if (list) {
             list.innerHTML =

src/popup/views/settings.js

@@ -44,6 +44,17 @@ let ctx;
 let versionClickCount = 0;
 let versionClickTimer = null;
 
+// The network that Settings was last drawn for. A follow of a switch saved
+// elsewhere sets `state` to the new network first. Settings is drawn again only
+// once the follow's write returns. So both "Save" buttons take this network,
+// not the one in `state`.
+let shownNetwork = null;
+
+// Each endpoint "Save" counts its taps here, under the field that it stores.
+// Once the user taps the same "Save" again, the earlier tap shows no flash
+// message. The earlier tap stores its URL only if its write had already begun.
+const saveTaps = { rpcUrl: 0, blockscoutUrl: 0 };
+
 // One row per site origin, however many addresses it appears under, each with
 // an [x] that hands it to onRemove.
 function renderSiteList(containerId, origins, onRemove) {
@@ -199,6 +210,7 @@ function renderWalletListSettings() {
 }
 
 function show() {
+    shownNetwork = currentNetwork();
     $("settings-rpc").value = state.rpcUrl;
     $("settings-blockscout").value = state.blockscoutUrl;
     $("settings-network").value = state.networkId;
@@ -306,6 +318,7 @@ function showNewSettings() {
         state.checkRecipientsOnEtherscan;
     if (state.currentView === "settings") {
         markViewRendered("settings");
+        shownNetwork = currentNetwork();
         $("settings-network").value = state.networkId;
         $("settings-rpc").value = state.rpcUrl;
         $("settings-blockscout").value = state.blockscoutUrl;
@@ -319,17 +332,70 @@ function showNewSettings() {
     updateDebugBanner(state.currentView);
 }
 
+// Saves `url` as `field` ("rpcUrl" or "blockscoutUrl") of the network
+// `networkId`, the one that Settings showed when the user tapped "Save". The
+// URL is set in `state` inside the save, holding the lock. So the page cannot
+// follow a switch saved elsewhere (followStoredSettings() in
+// src/popup/index.js) between setting the URL and writing it. If the active
+// network is no longer `networkId`, on this page or in the stored record,
+// nothing is saved. The flash message then says that the network changed.
+//
+// The save writes only the fields that differ from what this page last saved.
+// Another page may have stored a different URL since then. So `url` is set in
+// the stored record too. "Saved." then means that the stored record holds
+// `url`.
+//
+// `input` is the id of the input that the user typed `url` in. When another
+// page changes the network, "Use Blockscout" or "Check recipients on
+// Etherscan", this page draws Settings again. A redraw during the endpoint
+// check puts the URL from `state` back in the input. So if the input no longer
+// shows `url`, nothing is saved. The flash message then says that the URL was
+// changed during the check. The save compares the input and sets `url` in
+// `state` in one step. So a redraw after the comparison shows `url`.
+//
+// `tap` is the number of the "Save" tap that checked `url`. If the user taps
+// the same "Save" again before this save holds the lock, nothing is stored. If
+// the user taps the same "Save" again before the write ends, no flash message
+// is shown.
+async function saveEndpoint(field, input, url, networkId, tap) {
+    let refused = false;
+    let inputChanged = false;
+    await saveState((stored) => {
+        if (saveTaps[field] !== tap) return false;
+        refused =
+            state.networkId !== networkId || stored.networkId !== networkId;
+        inputChanged = $(input).value.trim() !== url;
+        if (refused || inputChanged) return false;
+        state[field] = url;
+        stored[field] = url;
+    });
+    if (saveTaps[field] !== tap) return;
+    if (refused) {
+        showFlash("The URL was not saved because the network changed.");
+    } else if (inputChanged) {
+        showFlash(
+            "The URL was not saved because it was changed during the check.",
+        );
+    } else {
+        showFlash("Saved.");
+    }
+}
+
 function init(_ctx) {
     ctx = _ctx;
     deleteWallet.init(ctx);
     showPhrase.init();
 
     $("btn-save-rpc").addEventListener("click", async () => {
+        saveTaps.rpcUrl++;
+        const tap = saveTaps.rpcUrl;
         const url = $("settings-rpc").value.trim();
         if (!url) {
             showFlash("Please enter an RPC URL.");
             return;
         }
+        // The URL is for the network that Settings shows when "Save" is tapped.
+        const net = shownNetwork;
         showFlash("Testing endpoint...");
         try {
             const resp = await debugFetch(url, {
@@ -343,12 +409,13 @@ function init(_ctx) {
                 }),
             });
             const json = await resp.json();
+            // The user has tapped this "Save" again since the check began.
+            if (tap !== saveTaps.rpcUrl) return;
             if (json.error) {
                 log.errorf("RPC validation error:", json.error);
                 showFlash("Endpoint returned an error.");
                 return;
             }
-            const net = currentNetwork();
             if (json.result !== net.chainId) {
                 showFlash("Wrong network: expected " + net.name + ".");
                 return;
@@ -357,6 +424,7 @@ function init(_ctx) {
             // Cancelled by the popup closing, not failed: see pageClosed in
             // src/popup/index.js.
             if (ctx.pageClosed.aborted) return;
+            if (tap !== saveTaps.rpcUrl) return;
             // Not the error's message: fetch puts the whole URL, password and
             // key included, in the message of the error it throws for a URL
             // with a user name and password or one it cannot parse.
@@ -364,34 +432,41 @@ function init(_ctx) {
             showFlash("Could not reach endpoint.");
             return;
         }
-        state.rpcUrl = url;
-        await saveState();
-        showFlash("Saved.");
+        await saveEndpoint("rpcUrl", "settings-rpc", url, net.id, tap);
     });
 
     $("btn-save-blockscout").addEventListener("click", async () => {
+        saveTaps.blockscoutUrl++;
+        const tap = saveTaps.blockscoutUrl;
         const url = $("settings-blockscout").value.trim();
         if (!url) {
             showFlash("Please enter a Blockscout API URL.");
             return;
         }
+        const net = shownNetwork;
         showFlash("Testing endpoint...");
         try {
             const resp = await debugFetch(url + "/stats");
+            if (tap !== saveTaps.blockscoutUrl) return;
             if (!resp.ok) {
                 showFlash("Endpoint returned HTTP " + resp.status + ".");
                 return;
             }
         } catch {
             if (ctx.pageClosed.aborted) return;
+            if (tap !== saveTaps.blockscoutUrl) return;
             // Not the error's message, as for the RPC check above.
             log.errorf("Blockscout validation failed:", urlOrigin(url));
             showFlash("Could not reach endpoint.");
             return;
         }
-        state.blockscoutUrl = url;
-        await saveState();
-        showFlash("Saved.");
+        await saveEndpoint(
+            "blockscoutUrl",
+            "settings-blockscout",
+            url,
+            net.id,
+            tap,
+        );
     });
 
     // Each change is made inside the save, holding the lock. So

src/popup/views/settingsAddToken.js

@@ -3,6 +3,7 @@ const { getTopTokens } = require("../../shared/tokenList");
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const { lookupTokenInfo } = require("../../shared/balances");
 const { isScamAddress } = require("../../shared/scamlist");
+const { isSpoofedSymbol } = require("../../shared/symbolSpoof");
 const { log } = require("../../shared/log");
 
 let ctx;
@@ -155,6 +156,16 @@ function init(_ctx) {
                 );
                 return;
             }
+            // The balance list never shows a token that the spoof rule
+            // refuses, so such a token is not tracked. The rule never refuses
+            // a bundled token, so the "Top tokens:" buttons and the top 100
+            // dropdown need no such check.
+            if (isSpoofedSymbol(info.symbol, addr)) {
+                showFlash("Not added: this token fakes a known symbol.");
+                infoEl.textContent = "";
+                infoEl.style.visibility = "hidden";
+                return;
+            }
             log.infof("Adding token", info.symbol, addr);
             state.trackedTokens.push({
                 address: addr,

src/popup/views/transactionDetail.js

@@ -311,10 +311,21 @@ function populateOnChainDetails(txData, chainId) {
     }
 }
 
+// Whether TransactionDetail still holds the transaction with `txHash` on
+// `chainId`. Opening another transaction replaces the one TransactionDetail
+// holds. A visit to Settings does not.
+function holdsTransaction(txHash, chainId) {
+    const tx = state.viewData.tx;
+    return tx?.hash === txHash && tx?.chainId === chainId;
+}
+
 // Reads the block, network details and calldata from Blockscout, and decodes
 // the calldata. While the stored "Use Blockscout" is off, Blockscout is not
 // asked. An answer that lands after the setting went off is dropped
 // (src/shared/storedSettings.js). Either way none of them is shown.
+//
+// Blockscout can answer after the user has opened another transaction. That
+// answer is dropped.
 async function loadFullTxDetails(txHash, chainId) {
     if (!(await storedSettingIsOn("useBlockscout"))) return;
     const section = $("tx-detail-calldata-section");
@@ -333,6 +344,7 @@ async function loadFullTxDetails(txHash, chainId) {
         if (!resp.ok) return;
         const txData = await resp.json();
         if (!(await storedSettingIsOn("useBlockscout"))) return;
+        if (!holdsTransaction(txHash, chainId)) return;
 
         // Populate on-chain detail fields (block, nonce, gas, fee)
         populateOnChainDetails(txData, chainId);

src/shared/chainSwitch.js

@@ -47,12 +47,63 @@ function clearPopupCaches() {
 // lock, so it is never switched while a follow of a switch saved elsewhere
 // waits for the lock (followStoredSettings() in src/popup/index.js): that
 // follow runs first, and this switch is made after it.
+//
+// The save writes only the fields that differ from what this page last saved.
+// When this page last saved a balance of "0", clearing that balance is no
+// change. So the switch also resets these fields in the stored record:
+//
+// - every address's balance and token balances;
+// - the time of the last balance refresh;
+// - the fraud contracts.
+//
+// A balance or a fraud contract that the background or another page stored
+// since this page's last save is then not kept under the new network
+// (https://git.eeqj.de/sneak/AutistMask/issues/653,
+// https://git.eeqj.de/sneak/AutistMask/issues/692).
+//
+// When the stored record is on another network, a switch saved elsewhere has
+// not reached this page yet. This page first takes that switch with
+// takeStoredNetwork() (state.js), as followStoredSettings() does. The switch to
+// `newNetworkId` is then made from the stored record's network. So every
+// network's list of tracked tokens in the stored record is kept
+// (https://git.eeqj.de/sneak/AutistMask/issues/701). When the stored record is
+// already on `newNetworkId`, the switch made from there only resets the
+// balances and caches.
+//
+// When the stored record is on this page's network, this page first takes the
+// stored `networkTrackedTokens` (takeStoredNetworkTrackedTokens() in state.js),
+// because another page's save may have changed a list this page holds.
+//
+// Before the switch, `state` takes the tracked tokens that another page stored
+// since this page's last save (takeStoredTrackedTokens() in state.js). The
+// switch then puts them away under the previous network, the network they were
+// added on.
 async function onChainSwitch(newNetworkId) {
-    const { state, saveState } = require("./state");
+    const {
+        state,
+        saveState,
+        takeStoredNetwork,
+        takeStoredTrackedTokens,
+        takeStoredNetworkTrackedTokens,
+    } = require("./state");
     let net = null;
-    await saveState(() => {
+    await saveState((stored) => {
         if (state.networkId === newNetworkId) return false;
+        if (stored.networkId !== state.networkId) {
+            takeStoredNetwork(stored);
+        } else {
+            takeStoredNetworkTrackedTokens(stored);
+        }
+        takeStoredTrackedTokens(stored);
         net = applyChainSwitchFields(state, newNetworkId);
+        stored.lastBalanceRefresh = 0;
+        stored.fraudContracts = [];
+        for (const wallet of stored.wallets) {
+            for (const addr of wallet.addresses) {
+                addr.balance = "0";
+                addr.tokenBalances = [];
+            }
+        }
         clearPopupCaches();
     });
     return net;

src/shared/state.js

@@ -125,11 +125,12 @@ function currentNetwork() {
     return networkById(state.networkId);
 }
 
-// The persisted fields as this page held them when its last loadState()
-// finished, or when its last successful saveState() began, with any network
-// switch saved elsewhere that this page has taken since (takeStoredNetwork()).
-// saveState() diffs the live state against this to find only the fields THIS
-// page changed since.
+// `baseline` holds the persisted fields as this page held them when its last
+// loadState() finished, or when its last successful saveState() began.
+// takeStoredNetwork(), takeStoredTrackedTokens() and
+// takeStoredNetworkTrackedTokens() also write into it what this page has taken
+// from the stored record since then. saveState() diffs the live state against
+// `baseline` to find only the fields THIS page changed since.
 //
 // Deep-cloned, not a reference: callers mutate persisted objects and arrays
 // in place (state.wallets.push(...)), and a reference baseline would mutate
@@ -401,6 +402,23 @@ function mergeNetworkEndpoints(base, ours, theirs) {
     return mergeMapByKey(base, ours, theirs, mergeEndpointEntry);
 }
 
+// Returns a copy of `stored.networkTrackedTokens` for when this page has not yet
+// taken the switch in `stored`. `page` is this page's state. A token that this
+// page tracked or removed since its last save is tracked or removed in the list
+// of `page.networkId`, by contract address.
+function networkTrackedTokensWithChange(stored, page) {
+    return {
+        ...stored.networkTrackedTokens,
+        [page.networkId]: mergeListByIdentity(
+            baseline.trackedTokens,
+            page.trackedTokens,
+            stored.networkTrackedTokens[page.networkId],
+            (token) => token.address.toLowerCase(),
+            (base, ours) => ours,
+        ),
+    };
+}
+
 // Read-modify-write, merged per field, rather than one full-blob write.
 //
 // Every extension page (the toolbar popup, a dApp approval window) holds its
@@ -442,8 +460,10 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 // milder than the other two.
 //
 // Every other persisted field stays a whole-field diff:
-// `trackedTokens`/`fraudContracts`/`viewStack` are arrays of scalars with no
-// per-element identity to merge by; `networkTrackedTokens` is diffed whole like
+// `fraudContracts`/`viewStack` are arrays of scalars with no per-element
+// identity to merge by; a save diffs `trackedTokens` whole, and a switch in
+// Settings first merges that list by contract address
+// (takeStoredTrackedTokens()); `networkTrackedTokens` is diffed whole like
 // `trackedTokens` and `networkId`, the two fields a network switch moves
 // together with it; `tokenHolderCache` is a map shaped like the ones above,
 // but nothing in src/ ever writes an entry into it — it is only ever reset
@@ -452,6 +472,11 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 // own UI scratch space, not data another page has any reason to share
 // membership of.
 //
+// One exception: when the stored record is on another network than this
+// page's, a save keeps the stored `trackedTokens`. It merges this page's change
+// into the list in `networkTrackedTokens` for this page's network, by contract
+// address.
+//
 // This does not make two pages that both change the SAME leaf concurrently
 // safe: last write wins on that one leaf, same as before. What it removes
 // is the cross-field (and now cross-membership-vs-leaf) clobber — a page
@@ -524,6 +549,20 @@ async function saveStateOnce(beforeWrite) {
             merged[key] = current[key];
         }
     }
+    // When the merged record names a network other than this page's, this page
+    // has not yet taken a switch saved elsewhere. This page's `trackedTokens`
+    // is then the list of this page's network. The stored record keeps the
+    // list of this page's network in `networkTrackedTokens`. So a token that
+    // this page added or removed since its last save is added to or removed
+    // from that stored list. The merged record keeps the stored `trackedTokens`
+    // (https://git.eeqj.de/sneak/AutistMask/issues/701).
+    if (merged.networkId !== current.networkId) {
+        merged.trackedTokens = fresh.trackedTokens;
+        merged.networkTrackedTokens = networkTrackedTokensWithChange(
+            fresh,
+            current,
+        );
+    }
     merged.hasWallet = Boolean(merged.wallets && merged.wallets.length > 0);
     // Stamped on every write, never merged or diffed: the record that goes to
     // storage is in THIS build's shape whatever shape it was read in, which is
@@ -591,8 +630,10 @@ function reportSaveFailure(err) {
 //
 // `beforeWrite`, when given, is called inside the lock with the stored record
 // as just read, before this page's state is compared against it. It may change
-// `state`, and this save writes that change. When it returns false, nothing is
-// written; any other return lets the save go ahead.
+// `state`, and this save writes that change. It may also change the stored
+// record. A field that this page did not change is then written as
+// `beforeWrite` left it. When it returns false, nothing is written; any other
+// return lets the save go ahead.
 function saveState(beforeWrite) {
     const turn = withLock("autistmask", () => saveStateOnce(beforeWrite));
     // Every failed save is reported, whether or not the caller awaited this
@@ -602,15 +643,62 @@ function saveState(beforeWrite) {
     return turn;
 }
 
-// Give this page the network switch held by `stored`, a record a save of this
-// page has just read (followStoredSettings() in src/popup/index.js calls this
-// from `beforeWrite`), in `state` and in `baseline` alike, as loadState() does
-// with a whole record. The switch is then not this page's own change, even when
+// Give this page the network switch held by `stored`, in `state` and in
+// `baseline` alike, as loadState() does with a whole record. `stored` is the
+// record that a save of this page has just read. followStoredSettings() in
+// src/popup/index.js and onChainSwitch() in src/shared/chainSwitch.js call this
+// from `beforeWrite`. The switch is then not this page's own change, even when
 // that save fails to write: a later switch back to the previous network still
 // differs from `baseline`, and is stored.
+//
+// A token that this page tracked or removed since its last save was tracked or
+// removed on this page's network before the switch. `state` keeps that change
+// in the list in `networkTrackedTokens` for that network, merged with the
+// stored list by contract address. `baseline` takes the stored list, so the
+// save stores the change (https://git.eeqj.de/sneak/AutistMask/issues/706).
 function takeStoredNetwork(stored) {
+    const networkTrackedTokens = networkTrackedTokensWithChange(
+        stored,
+        rawState,
+    );
     copyChainSwitchFields(rawState, stored);
     copyChainSwitchFields(baseline, structuredClone(stored));
+    rawState.networkTrackedTokens = networkTrackedTokens;
+}
+
+// Give this page the tracked tokens of `stored`, a record on this page's
+// network that a save of this page has just read (onChainSwitch() in
+// src/shared/chainSwitch.js calls this from `beforeWrite`):
+//
+// - A token that another page tracked or removed since this page's last save
+//   is tracked or removed in `state` too.
+// - A token that this page tracked or removed since then stays as this page
+//   has it.
+//
+// `baseline` takes the stored list, so the save stores the list in `state`
+// whenever the two differ.
+function takeStoredTrackedTokens(stored) {
+    rawState.trackedTokens = mergeListByIdentity(
+        baseline.trackedTokens,
+        rawState.trackedTokens,
+        stored.trackedTokens,
+        (token) => token.address.toLowerCase(),
+        (base, ours) => ours,
+    );
+    baseline.trackedTokens = structuredClone(stored.trackedTokens);
+}
+
+// Give `state` and `baseline` each their own copy of the stored
+// `networkTrackedTokens`. `stored` is a record on this page's network that a
+// save of this page has just read. onChainSwitch() in
+// src/shared/chainSwitch.js calls this from `beforeWrite`.
+function takeStoredNetworkTrackedTokens(stored) {
+    rawState.networkTrackedTokens = structuredClone(
+        stored.networkTrackedTokens,
+    );
+    baseline.networkTrackedTokens = structuredClone(
+        stored.networkTrackedTokens,
+    );
 }
 
 // Rejects with StateUnusableError for a stored record this build cannot make
@@ -659,6 +747,8 @@ module.exports = {
     saveState,
     onSaveFailure,
     takeStoredNetwork,
+    takeStoredTrackedTokens,
+    takeStoredNetworkTrackedTokens,
     loadState,
     currentAddress,
     currentNetwork,

src/shared/storedSettings.js

@@ -1,5 +1,5 @@
-// Reads "Use Blockscout" or "Check recipients on Etherscan" from the stored
-// profile.
+// Reads "Use Blockscout", "Check recipients on Etherscan" or the active network
+// from the stored profile.
 //
 // Before each request that sends the user's data to Blockscout or Etherscan, the
 // wallet reads that service's setting from storage. The wallet reads the setting
@@ -7,6 +7,11 @@
 // made, and an answer that lands after the setting went off is dropped. A page's
 // own copy of the setting is not used, because another page may have just
 // changed it.
+//
+// Before asking Blockscout for the transaction history, a screen remembers
+// which network is active. If another network is active on the page or in
+// storage when the answer lands, the screen drops the answer. A switch saved
+// elsewhere reaches storage first and the page later.
 
 const { storageGet } = require("./browserApi");
 const { normalizePersisted } = require("./persistedState");
@@ -24,4 +29,15 @@ async function storedSettingIsOn(name) {
     }
 }
 
-module.exports = { storedSettingIsOn };
+// Whether `networkId` is the active network in the stored profile. A failed
+// read counts as no.
+async function storedNetworkIs(networkId) {
+    try {
+        const { autistmask } = await storageGet("autistmask");
+        return normalizePersisted(autistmask).networkId === networkId;
+    } catch {
+        return false;
+    }
+}
+
+module.exports = { storedSettingIsOn, storedNetworkIs };

src/shared/uniswap.js

@@ -479,6 +479,17 @@ function tokenInfo(address, sources) {
     };
 }
 
+// The token of a Permit2 allowance or of a PERMIT2_TRANSFER_FROM, in the
+// shape tokenInfo() gives. Permit2 has no allowance of ETH and moves no ETH.
+// The zero address there reads as a token nothing knows: its amount in base
+// units, and the zero address as its token.
+function permit2TokenInfo(address, sources) {
+    if (address === "0x0000000000000000000000000000000000000000") {
+        return { symbol: null, decimals: null, address };
+    }
+    return tokenInfo(address, sources);
+}
+
 // A swap amount line. With a scale it is the token quantity; with none it is
 // the base-unit integer with the unknown scale stated, the same refusal the
 // ERC-20 amount line makes, so the screen has one way of saying it. `display`
@@ -497,16 +508,18 @@ function amountText(raw, info) {
 
 // The line giving a moved token, or the token of a permit, under `label`, in
 // the shape of the Token In line, so the screens show it as they show that
-// one. ETH has no address.
-function tokenMovedLine(label, token, sources) {
-    const info = tokenInfo(token, sources);
+// one. `info` is what tokenInfo() or permit2TokenInfo() gives for the token.
+// ETH has no address.
+function tokenMovedLine(label, info) {
     if (!present(info.address)) {
         return { label, value: info.symbol };
     }
     return {
         label,
-        value: info.symbol ? info.symbol + " (" + token + ")" : token,
-        address: token,
+        value: info.symbol
+            ? info.symbol + " (" + info.address + ")"
+            : info.address,
+        address: info.address,
         isToken: true,
     };
 }
@@ -975,6 +988,9 @@ function totalAmount(amounts) {
 // pays it of Token In as the step's amount in place of the rules' Amount, or
 // no amount when this decoder cannot tell what that is.
 //
+// `spent` lists the currency that each swap action spends, for each swap
+// action that this decoder could read.
+//
 // `takes` is every TAKE, TAKE_ALL and TAKE_PORTION, as the currency it takes
 // and its recipient as written, MSG_SENDER for a TAKE_ALL. TAKE_PORTION takes
 // a share of the currency, so it does not name the output side as TAKE does.
@@ -1150,6 +1166,8 @@ function decodeV4Swap(input) {
             }
         }
 
+        const spent = swaps.map((s) => s.tokenIn);
+
         // Rule 3.
         if (swapUndecoded) {
             return {
@@ -1157,6 +1175,7 @@ function decodeV4Swap(input) {
                 tokenOut: takeToken,
                 amountIn: null,
                 amountOutMin: null,
+                spent,
                 takes,
                 settledFromRouter,
                 paidByUser,
@@ -1167,7 +1186,6 @@ function decodeV4Swap(input) {
             };
         }
 
-        const spent = swaps.map((s) => s.tokenIn);
         const bought = swaps.map((s) => s.tokenOut);
 
         // Rules 1 and 2 for Token In.
@@ -1203,6 +1221,7 @@ function decodeV4Swap(input) {
             tokenOut,
             amountIn,
             amountOutMin,
+            spent,
             takes,
             settledFromRouter,
             paidByUser,
@@ -1240,9 +1259,10 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         let inputEstablished = false;
         // Whether the user pays the step that set the input side: a V2 or V3
         // swap step with `payerIsUser` true, a V4 step the user pays some of
-        // its input currency (see decodeV4Swap()), or a WRAP_ETH, whose ETH
-        // comes from the transaction's value. A step paid from the router
-        // takes nothing from the sender.
+        // its input currency (see paidByUser in the loop), or a WRAP_ETH,
+        // whose ETH comes from the transaction's value. A step that pays an
+        // ERC-20 token from the router takes none of that token from the
+        // sender.
         let inputPaidByUser = false;
         // The last PERMIT2_PERMIT this decoder read before a step set the
         // input side, or null (see permitStands after the loop).
@@ -1293,8 +1313,9 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         const commandNames = [];
 
         // THE INVARIANT: an amount and the token it is counted in always come
-        // from the same hop, or from hops that all spend that token. A figure
-        // is never rendered against a token that did not supply it.
+        // from the same hop, or from hops that all spend that token or all buy
+        // it. A figure is never rendered against a token that did not supply
+        // it.
         //
         // Both sides are therefore set as a PAIR — never field by field, and
         // never on truthiness. An address is never falsy once set but an
@@ -1338,7 +1359,9 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // What the steps take from the sender beyond the amount of the step
         // that sets the input side, as { token, amount }, in step order.
         // After the loop each joins the Amount line or gets lines of its own
-        // (see permitStands).
+        // (see permitStands). A take with `atMost` set may take less than
+        // `amount`: it never joins the Amount line, and its line reads
+        // "Up to" and the amount.
         const userPaid = [];
         // A swap step the user pays for (`payerIsUser` true) takes `amount`
         // of `token` from the sender. A V2 exact-in of ALREADY_PAID takes
@@ -1407,6 +1430,10 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             const r = recipient.toLowerCase();
             return r === ADDRESS_THIS || r === toAddress.toLowerCase();
         };
+        const isSender = (recipient) => {
+            const r = recipient.toLowerCase();
+            return r === MSG_SENDER || r === sender;
+        };
         // A swap step or V4 SETTLE pays `amount` of `token` from the router's
         // own balance. CONTRACT_BALANCE pays all of it. Any other quantity
         // counts against the amount a WRAP_ETH stated, and the steps pay all
@@ -1439,17 +1466,73 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // A step pays `recipient`. `output` is the token a swap step or a V4
         // TAKE or TAKE_PORTION pays; other steps pass none.
         const addPayee = (recipient, output) => {
-            const r = recipient.toLowerCase();
             if (isRouter(recipient)) {
                 if (present(output)) {
                     heldByRouter.set(output.toLowerCase(), null);
                 }
-            } else if (r === MSG_SENDER || r === sender) {
+            } else if (isSender(recipient)) {
                 paidToSender = true;
             } else {
                 addPaidElsewhere(recipient);
             }
         };
+        // Each swap step that paid the sender some of the token it bought,
+        // as { step, token, amount, onlyToSender }:
+        // - `step` is the step's index;
+        // - `token` is that token;
+        // - `amount` is the step's stated minimum;
+        // - `onlyToSender` is whether the step paid all of that token to the
+        //   sender.
+        // A later step that spends that token takes the step off this list
+        // (see dropFromSum()).
+        let swapsPayingSender = [];
+        // The step being read spends `token`, so it may spend what an earlier
+        // swap step paid the sender. Each step on swapsPayingSender that
+        // bought `token` leaves the list. A step spends a token as follows:
+        // - a V2 or V3 swap step spends its input token;
+        // - a V4 step spends each token that one of its swap actions spends,
+        //   and each token that one of its SETTLEs or SETTLE_ALLs pays;
+        // - a PERMIT2_TRANSFER_FROM spends the token it moves.
+        const dropFromSum = (token) => {
+            swapsPayingSender = swapsPayingSender.filter(
+                (s) => !sameAddress(s.token, token),
+            );
+        };
+        // The minimum the output side shows for the swap step at `step`. The
+        // step buys `token` with the stated minimum `amount`, and pays
+        // `token` to `recipients`. The minimum is the step's own, unless this
+        // step and an earlier one on swapsPayingSender both pay `token` to
+        // the sender, as a route split across steps does. The minimum is then
+        // the total of all such steps' minimums. There is none when this
+        // decoder reads no minimum from one of them, or when one of them pays
+        // some of `token` elsewhere. There is also none when this decoder did
+        // not read one of them, or a step between them, in full (see
+        // stepsUnread).
+        const swapMinimum = (step, token, amount, recipients) => {
+            const toSender = recipients.filter(
+                (r) => present(r) && isSender(r),
+            );
+            if (toSender.length === 0) return amount;
+            swapsPayingSender.push({
+                step,
+                token,
+                amount,
+                onlyToSender: toSender.length === recipients.length,
+            });
+            const split = swapsPayingSender.filter((s) =>
+                sameAddress(s.token, token),
+            );
+            if (split.length < 2) return amount;
+            if (
+                split.some(
+                    (s) => !s.onlyToSender || typeof s.amount !== "bigint",
+                ) ||
+                stepsUnread.some((unread) => unread >= split[0].step)
+            ) {
+                return null;
+            }
+            return split.reduce((sum, s) => sum + s.amount, 0n);
+        };
         // A step that pays `token` to `recipient` is a hop, not a payout,
         // when the very next step is a V2 exact-in whose input is already
         // paid, whose path starts at `token`, and whose pair (see v2PairFor())
@@ -1591,6 +1674,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                                     : null,
                         });
                     }
+                    if (p) dropFromSum(p.token);
                 } else if (command === "BALANCE_CHECK_ERC20") {
                     const b = decodeBalanceCheck(inputs[i]);
                     if (!b) {
@@ -1613,13 +1697,13 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     } else {
                         // The router passes this check whenever the owner
                         // holds at least minBalance, so a zero one guarantees
-                        // nothing and does not replace a minimum an earlier
-                        // step stated. A check the router lets fail guarantees
-                        // nothing either, so it is read as a zero one. Any
+                        // nothing. A check the router lets fail guarantees
+                        // nothing either, so it is read as a zero one. A zero
+                        // check sets neither Token Out nor the minimum. Any
                         // other minBalance sets the output side as a swap
-                        // does. It pays nobody.
+                        // does. The check pays nobody.
                         const minBalance = allowedToFail ? 0n : b.minBalance;
-                        if (!(minBalance === 0n && present(minOutput))) {
+                        if (minBalance !== 0n) {
                             setOutput(i, b.token, minBalance, []);
                         }
                         keepsRouterWeth = true;
@@ -1633,10 +1717,18 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         } else if (s.payerIsUser) {
                             addUserPaid(s.tokenIn, s.amountIn);
                         }
+                        dropFromSum(s.tokenIn);
                         // Always update output: in multi-step swaps (V3 → V4),
-                        // the last swap step determines the final output token
-                        // and minimum received amount.
-                        setOutput(i, s.tokenOut, s.amountOutMin, [s.recipient]);
+                        // the last swap step determines the final output
+                        // token. swapMinimum() gives the minimum.
+                        setOutput(
+                            i,
+                            s.tokenOut,
+                            swapMinimum(i, s.tokenOut, s.amountOutMin, [
+                                s.recipient,
+                            ]),
+                            [s.recipient],
+                        );
                         if (!s.payerIsUser) {
                             spendFromRouter(s.tokenIn, s.amountIn);
                         }
@@ -1657,7 +1749,15 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         } else if (s.payerIsUser) {
                             addUserPaid(s.tokenIn, s.amountIn);
                         }
-                        setOutput(i, s.tokenOut, s.amountOutMin, [s.recipient]);
+                        dropFromSum(s.tokenIn);
+                        setOutput(
+                            i,
+                            s.tokenOut,
+                            swapMinimum(i, s.tokenOut, s.amountOutMin, [
+                                s.recipient,
+                            ]),
+                            [s.recipient],
+                        );
                         if (!s.payerIsUser) {
                             spendFromRouter(s.tokenIn, s.amountIn);
                         }
@@ -1689,7 +1789,15 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         } else if (s.payerIsUser) {
                             addUserPaid(s.tokenIn, s.amountInMax);
                         }
-                        setOutput(i, s.tokenOut, s.amountOut, [s.recipient]);
+                        dropFromSum(s.tokenIn);
+                        setOutput(
+                            i,
+                            s.tokenOut,
+                            swapMinimum(i, s.tokenOut, s.amountOut, [
+                                s.recipient,
+                            ]),
+                            [s.recipient],
+                        );
                         if (!isHop(i, s.tokenOut, s.recipient)) {
                             addPayee(s.recipient, s.tokenOut);
                         }
@@ -1815,6 +1923,41 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                 } else if (command === "V4_SWAP") {
                     const v4 = decodeV4Swap(inputs[i]);
                     const inputSetBefore = inputEstablished;
+                    // V4Router pays a SETTLE of ETH from the router's own
+                    // ETH, whichever payer the SETTLE names. The router holds
+                    // the transaction's value, and any ETH an earlier step
+                    // left it (see heldByRouter). So the user also pays a
+                    // SETTLE of ETH that names the router as payer. The user
+                    // pays all of its amount when the router holds no other
+                    // ETH, and up to its amount otherwise. CONTRACT_BALANCE
+                    // pays all the router holds, an amount the calldata does
+                    // not state.
+                    const routerHeldEth = heldByRouter.has(
+                        "0x0000000000000000000000000000000000000000",
+                    );
+                    const ethFromRouter = (v4?.settledFromRouter ?? [])
+                        .filter(
+                            (s) =>
+                                s.currency ===
+                                "0x0000000000000000000000000000000000000000",
+                        )
+                        .map((s) => ({
+                            currency: s.currency,
+                            amount:
+                                s.amount === CONTRACT_BALANCE ? null : s.amount,
+                        }));
+                    // What the user pays the step: what decodeV4Swap() says,
+                    // and the ETH of each SETTLE from the router of a known
+                    // amount when the router holds no other ETH.
+                    const paidByUser = v4
+                        ? v4.paidByUser.concat(
+                              routerHeldEth
+                                  ? []
+                                  : ethFromRouter.filter((s) =>
+                                        present(s.amount),
+                                    ),
+                          )
+                        : [];
                     if (v4) {
                         // Each SETTLE paid from the router spends the amount
                         // decodeV4Swap() says it pays.
@@ -1826,6 +1969,11 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                                 addPayee(t.recipient, t.currency);
                             }
                         }
+                        for (const token of v4.spent) dropFromSum(token);
+                        for (const s of v4.paidByUser) dropFromSum(s.currency);
+                        for (const s of v4.settledFromRouter) {
+                            dropFromSum(s.currency);
+                        }
                     }
                     if (!v4 || v4.recipientUnread) {
                         payeeUnread = true;
@@ -1845,10 +1993,10 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         commandNames[i] += " (could not be decoded)";
                     }
                     // The step's amount, if it sets the input side: what the
-                    // user pays it of its input currency (see
-                    // decodeV4Swap()), or, when the user pays none of it,
-                    // what its swap actions spend of it, whoever pays that.
-                    const paidIn = v4?.paidByUser.find(
+                    // user pays it of its input currency, or, when the user
+                    // pays none of it, what its swap actions spend of it,
+                    // whoever pays that.
+                    const paidIn = paidByUser.find(
                         (p) => p.currency === v4.tokenIn,
                     );
                     const amountIn = paidIn ? paidIn.amount : v4?.amountIn;
@@ -1874,7 +2022,12 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                             setInput(v4.tokenIn, amountIn);
                         }
                         outputToken = v4.tokenOut;
-                        minOutput = v4.amountOutMin;
+                        minOutput = swapMinimum(
+                            i,
+                            v4.tokenOut,
+                            v4.amountOutMin,
+                            takeRecipients,
+                        );
                         outputEstablished = true;
                         outputUnwrapped = false;
                         unwrapIntoRouterStep = null;
@@ -1902,10 +2055,24 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     // router still runs it.
                     const setInputHere = inputEstablished && !inputSetBefore;
                     if (setInputHere) inputPaidByUser = paidIn !== undefined;
-                    if (v4) {
-                        for (const p of v4.paidByUser) {
-                            if (setInputHere && p === paidIn) continue;
-                            addUserPaid(p.currency, p.amount);
+                    for (const p of paidByUser) {
+                        if (setInputHere && p === paidIn) continue;
+                        addUserPaid(p.currency, p.amount);
+                    }
+                    // A SETTLE of ETH from the router that `paidByUser` leaves
+                    // out is a take of its own, even on the step that sets
+                    // the input side. Either this decoder does not know its
+                    // amount, or ETH an earlier step left in the router may
+                    // pay part of that amount (see userPaid).
+                    for (const p of ethFromRouter) {
+                        if (!present(p.amount)) {
+                            addUserPaid(p.currency, null);
+                        } else if (routerHeldEth) {
+                            userPaid.push({
+                                token: p.currency,
+                                amount: p.amount,
+                                atMost: true,
+                            });
                         }
                     }
                     if (!v4 || v4.settleUnread) {
@@ -2013,10 +2180,10 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // The total is what the steps take of Token In: the amount of the
         // step that set the input side, with each later take of that token
         // added to it while both are quantities. A take that cannot be added,
-        // being of another token or coming after an amount that is not a
-        // quantity (a V4 open delta, ALREADY_PAID, or none stated), gets
-        // lines of its own. One whose amount is not known also leaves the
-        // total unknown, with no figure.
+        // being of another token, coming after an amount that is not a
+        // quantity (a V4 open delta, ALREADY_PAID, or none stated), or having
+        // `atMost` set, gets lines of its own. One whose amount is not known
+        // also leaves the total unknown, with no figure.
         //
         // A PERMIT2_PERMIT names Token In only when its amount stands as the
         // Amount figure in place of the total, which it does only in the
@@ -2032,12 +2199,14 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // it may take more. A later permit or batch, or a later step this
         // decoder did not read, may raise what Permit2 lets the router take.
         // Every other PERMIT2_PERMIT leaves Token In and the Amount line as
-        // they read with no permit, and gets lines of its own below. A step
-        // that may take from the sender what this decoder did not read leaves
-        // no figure, permit or not (see spentUnread()), and so do a permit
-        // or batch whose input it cannot read (see permitUnread()) and an
-        // allowance of Token In to another spender (see toAnotherSpender). An
-        // EXECUTE_SUB_PLAN step leaves both sides unknown (below).
+        // they read with no permit, and gets lines of its own below. A permit
+        // on the zero address never stands as the Amount figure, because
+        // Permit2 has no allowance of ETH. A step that may take from the
+        // sender what this decoder did not read leaves no figure, permit or
+        // not (see spentUnread()), and so do a permit or batch whose input it
+        // cannot read (see permitUnread()) and an allowance of Token In to
+        // another spender (see toAnotherSpender). An EXECUTE_SUB_PLAN step
+        // leaves both sides unknown (below).
         const stepCommands = Array.from(
             commandsBytes,
             (b) => commands[b & commandTypeMask],
@@ -2047,6 +2216,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             stepCommands.filter((c) => c === "PERMIT2_PERMIT").length === 1 &&
             !stepCommands.includes("PERMIT2_PERMIT_BATCH") &&
             sameAddress(permit.spender, toAddress) &&
+            permit.token !== "0x0000000000000000000000000000000000000000" &&
             !permit.allowedToFail &&
             permit.beforeEveryTake &&
             !stepsUnread.some((step) => step > permit.step);
@@ -2057,14 +2227,14 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         let total = null;
         // The takes from the sender that `total` adds up, each a quantity, as
         // { token, amount }. When there is no Amount line, each gets lines of
-        // its own (see below). The amount of a step that set the input side
-        // and is paid from the router counts in `total` but is not among them.
+        // its own (see below). The amount of the step that set the input side
+        // counts in `total` whoever pays that step. That amount is among them
+        // only when the user pays the step (see inputPaidByUser).
         const inTotal = [];
         // Whether the step that set the input side counts as a take from the
         // sender, which may get lines of its own. The amount it stated counts
         // whoever pays it. Stating none, it counts only when the user pays it
-        // some of its input token: paid from the router, it takes nothing
-        // from the sender.
+        // some of its input token.
         const hasFirstTake =
             inputEstablished && (present(inputAmount) || inputPaidByUser);
         // The take of the step that set the input side, when the total
@@ -2090,7 +2260,8 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             if (
                 ofTokenIn &&
                 typeof total === "bigint" &&
-                typeof t.amount === "bigint"
+                typeof t.amount === "bigint" &&
+                !t.atMost
             ) {
                 total += t.amount;
                 inTotal.push(t);
@@ -2193,8 +2364,9 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // V2's already-paid zero, neither of which is a quantity at all (see
         // OPEN_DELTA and ALREADY_PAID), and an unbounded permit. Those two
         // tests come first — the sentinels are not bigints and cannot be
-        // compared with one.
-        const spentText = (amount, info) => {
+        // compared with one. `atMost` marks an amount that is only the most a
+        // take may be (see userPaid).
+        const spentText = (amount, info, atMost) => {
             if (amount === OPEN_DELTA) {
                 return { raw: OPEN_DELTA_AMOUNT, display: OPEN_DELTA_AMOUNT };
             }
@@ -2207,7 +2379,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             if (amount >= MAX_UINT160) {
                 return { raw: "Unlimited", display: "Unlimited" };
             }
-            if (hasV2OrV3ExactOut) {
+            if (hasV2OrV3ExactOut || atMost) {
                 // A V2 or V3 exact-out swap spends at most this figure,
                 // whichever steps gave it (an amountInMax, the WRAP_ETH of a
                 // swap paid in ETH, a permit, or several steps' total), so it
@@ -2234,17 +2406,19 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // A null token in `spentFromSender`, a step this decoder did not read
         // or a token it does not know, and an allowance to another spender
         // that may be of Token In, leave no Amount figure, which may then be
-        // too low. With no Amount line, each take the total adds up gets
-        // lines of its own, first, so that every amount this decoder read is
-        // shown.
+        // too low. An allowance of the zero address is never one of Token In,
+        // because Permit2 has no allowance of ETH. With no Amount line, each
+        // take the total adds up gets lines of its own, first, so that every
+        // amount this decoder read is shown.
         if (
             present(inputAmount) &&
             spentFromSender.every((s) => present(s.token)) &&
             toAnotherSpender.every(
                 (p) =>
-                    present(p.token) &&
-                    present(inputToken) &&
-                    !sameAddress(p.token, inputToken),
+                    p.token === "0x0000000000000000000000000000000000000000" ||
+                    (present(p.token) &&
+                        present(inputToken) &&
+                        !sameAddress(p.token, inputToken)),
             )
         ) {
             const amount = spentText(inputAmount, inInfo);
@@ -2265,11 +2439,14 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             details.push({
                 label: "Moved from the sender",
                 value: present(s.amount)
-                    ? spentText(s.amount, tokenInfo(s.token, sources)).display
+                    ? spentText(s.amount, tokenInfo(s.token, sources), s.atMost)
+                          .display
                     : UNDECODED_CURRENCY,
             });
             if (present(s.token)) {
-                details.push(tokenMovedLine("Token moved", s.token, sources));
+                details.push(
+                    tokenMovedLine("Token moved", tokenInfo(s.token, sources)),
+                );
                 details.push({
                     label: "Moved to",
                     value: "The swap step that spends it",
@@ -2280,12 +2457,12 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // What each PERMIT2_TRANSFER_FROM moves: its amount, its token and
         // where it goes, an address on a line of its own.
         for (const m of movedFromSender) {
+            const info = permit2TokenInfo(m.token, sources);
             details.push({
                 label: "Moved from the sender",
-                value: amountText(m.amount, tokenInfo(m.token, sources))
-                    .display,
+                value: amountText(m.amount, info).display,
             });
-            details.push(tokenMovedLine("Token moved", m.token, sources));
+            details.push(tokenMovedLine("Token moved", info));
             details.push(
                 present(m.to)
                     ? { label: "Moved to", value: m.to }
@@ -2315,15 +2492,15 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                 });
                 continue;
             }
+            const info = permit2TokenInfo(p.token, sources);
             details.push({
                 label: "Permit2 allowance",
                 value:
                     p.amount >= MAX_UINT160
                         ? "Unlimited"
-                        : amountText(p.amount, tokenInfo(p.token, sources))
-                              .display,
+                        : amountText(p.amount, info).display,
             });
-            details.push(tokenMovedLine("Allowance token", p.token, sources));
+            details.push(tokenMovedLine("Allowance token", info));
             details.push({
                 label: "Allowance spender",
                 value: p.spender,
@@ -2381,7 +2558,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             paidTo.push({ label: "Paid to", value: PAID_TO_BRIDGE });
         }
         for (const m of movedIntoRouter) {
-            const info = tokenInfo(m.token, sources);
+            const info = permit2TokenInfo(m.token, sources);
             paidTo.push({
                 label: "Paid to",
                 value:
@@ -2389,9 +2566,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     amountText(m.amount, info).display +
                     " from the sender (later steps may not spend all of it)",
             });
-            paidTo.push(
-                tokenMovedLine("Token moved into the router", m.token, sources),
-            );
+            paidTo.push(tokenMovedLine("Token moved into the router", info));
         }
         if (outputHeld) {
             paidTo.push({ label: "Paid to", value: STAYS_IN_ROUTER });
@@ -2408,8 +2583,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             paidTo.push(
                 tokenMovedLine(
                     "Token moved into the router",
-                    getAddress(token),
-                    sources,
+                    tokenInfo(getAddress(token), sources),
                 ),
             );
         }

tests/addTokenLateAnswer.test.js

@@ -0,0 +1,137 @@
+// A contract lookup on AddToken can answer after the user has left AddToken.
+// The token is still added, and the screen the user is on does not change
+// (https://git.eeqj.de/sneak/AutistMask/issues/603). An answer while AddToken
+// still shows goes to AddressDetail. Driven through the real popup over a
+// stored profile.
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+    TOKEN_ADDRESS,
+} = require("./support/popupBoot");
+
+const TOKEN = {
+    address: TOKEN_ADDRESS,
+    symbol: "TST",
+    decimals: 18,
+    name: "Test Token",
+};
+
+// A second contract address, typed after AddToken was opened again.
+const OTHER_TOKEN_ADDRESS = "0xBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB";
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+// The popup reopened onto AddressDetail, then AddToken opened from it with
+// TOKEN's contract address typed in.
+async function openAddToken() {
+    const boot = await bootPopup(
+        unversionedValidProfile({
+            currentView: "address",
+            selectedWallet: 0,
+            selectedAddress: 0,
+        }),
+    );
+    expect(boot.pageErrors).toEqual([]);
+    await boot.click("btn-add-token");
+    expect(boot.visibleViews()).toEqual(["add-token"]);
+    boot.node("add-token-address").value = TOKEN.address;
+    return boot;
+}
+
+// Presses Add with a contract lookup that answers only when the function
+// returned here is called. That function waits for Add to finish.
+function addWithPendingLookup(boot) {
+    const { lookupTokenInfo } = require("../src/shared/balances");
+    let answer;
+    lookupTokenInfo.mockImplementationOnce(
+        () =>
+            new Promise((resolve) => {
+                answer = resolve;
+            }),
+    );
+    const adding = boot.click("btn-add-token-confirm");
+    return async () => {
+        answer({
+            symbol: TOKEN.symbol,
+            decimals: TOKEN.decimals,
+            name: TOKEN.name,
+        });
+        await adding;
+    };
+}
+
+test("an answer after the user opened Settings adds the token and Settings stays", async () => {
+    const boot = await openAddToken();
+    const answerLookup = addWithPendingLookup(boot);
+    await boot.click("btn-settings");
+    expect(boot.visibleViews()).toEqual(["settings"]);
+
+    await answerLookup();
+    expect(boot.visibleViews()).toEqual(["settings"]);
+    expect(boot.storage.read("autistmask").trackedTokens).toEqual([TOKEN]);
+});
+
+test("Back from Settings onto AddToken after the lookup answered shows no lookup status", async () => {
+    const boot = await openAddToken();
+    const answerLookup = addWithPendingLookup(boot);
+    expect(boot.text("add-token-info")).toBe("Looking up token...");
+    await boot.click("btn-settings");
+    await answerLookup();
+
+    await boot.click("btn-settings-back");
+    expect(boot.visibleViews()).toEqual(["add-token"]);
+    expect(boot.text("add-token-info")).toBe("");
+    expect(boot.node("add-token-info").style.visibility).toBe("hidden");
+});
+
+test("an answer after AddToken was opened again adds the token and leaves AddToken and its status line as they are", async () => {
+    const boot = await openAddToken();
+    const answerFirstLookup = addWithPendingLookup(boot);
+    await boot.click("btn-add-token-back");
+    await boot.click("btn-add-token");
+    expect(boot.visibleViews()).toEqual(["add-token"]);
+    boot.node("add-token-address").value = OTHER_TOKEN_ADDRESS;
+    // The second lookup is never answered.
+    addWithPendingLookup(boot);
+
+    await answerFirstLookup();
+    expect(boot.visibleViews()).toEqual(["add-token"]);
+    expect(boot.text("add-token-info")).toBe("Looking up token...");
+    expect(boot.storage.read("autistmask").trackedTokens).toEqual([TOKEN]);
+});
+
+test("a lookup that fails after AddToken was opened again leaves the status line as it is", async () => {
+    const boot = await openAddToken();
+    const { lookupTokenInfo } = require("../src/shared/balances");
+    let failFirstLookup;
+    lookupTokenInfo.mockImplementationOnce(
+        () =>
+            new Promise((_, reject) => {
+                failFirstLookup = reject;
+            }),
+    );
+    const firstAdd = boot.click("btn-add-token-confirm");
+    await boot.click("btn-add-token-back");
+    await boot.click("btn-add-token");
+    boot.node("add-token-address").value = OTHER_TOKEN_ADDRESS;
+    // The second lookup is never answered.
+    addWithPendingLookup(boot);
+
+    failFirstLookup(new Error("lookup failed"));
+    await firstAdd;
+    expect(boot.text("add-token-info")).toBe("Looking up token...");
+});
+
+test("an answer while AddToken still shows goes to AddressDetail with the token listed", async () => {
+    const boot = await openAddToken();
+    const answerLookup = addWithPendingLookup(boot);
+
+    await answerLookup();
+    expect(boot.visibleViews()).toEqual(["address"]);
+    expect(boot.node("address-balances").innerHTML).toContain("TST");
+    expect(boot.storage.read("autistmask").trackedTokens).toEqual([TOKEN]);
+});

tests/addressKey.test.js

@@ -161,7 +161,7 @@ function click(element) {
 
 // show() starts the fee estimate without awaiting it; this lets it settle.
 async function settle() {
-    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+    for (let i = 0; i < 10; i++) await jest.advanceTimersByTimeAsync(0);
 }
 
 // ------------------------------------------------------------ harness
@@ -188,7 +188,11 @@ let sent;
 // handler to the buttons it drew, as the browser's fresh list would have.
 let plusButton;
 
+// showFlash() starts a timer that clears the message one or two seconds later.
+// Each test here runs on fake timers and drops them in afterEach, so that timer
+// never outlives the test.
 beforeEach(() => {
+    jest.useFakeTimers();
     approvalDetails = null;
     sent = [];
     mockNode.broadcast = [];
@@ -239,6 +243,7 @@ beforeEach(() => {
 });
 
 afterEach(() => {
+    jest.useRealTimers();
     jest.restoreAllMocks();
 });
 

tests/backgroundApproval.test.js

@@ -537,7 +537,18 @@ async function settleIncludingRejections() {
     await new Promise((resolve) => setImmediate(resolve));
 }
 
+// While an approval is pending, the background starts a 20-second timer to
+// keep itself running. The timer is stubbed and never starts, so no test in
+// this file leaves it running.
+let keepRunningTimer;
+beforeEach(() => {
+    keepRunningTimer = jest
+        .spyOn(global, "setInterval")
+        .mockImplementation(() => 1);
+});
+
 afterEach(() => {
+    keepRunningTimer.mockRestore();
     delete global.chrome;
     jest.resetModules();
 });
@@ -1883,18 +1894,6 @@ describe("a closed approval window leaves the request pending", () => {
         return bg.actionPopups[bg.actionPopups.length - 1];
     }
 
-    // The timer that keeps the worker running while an approval is pending is
-    // stubbed, so no test here leaves that timer running when it ends.
-    let keepRunningTimer;
-    beforeEach(() => {
-        keepRunningTimer = jest
-            .spyOn(global, "setInterval")
-            .mockImplementation(() => 1);
-    });
-    afterEach(() => {
-        keepRunningTimer.mockRestore();
-    });
-
     test("the toolbar popup opens a closed transaction approval, and approving it there sends", async () => {
         const bg = loadBackground();
         const pending = bg.requestTx();

tests/backgroundStateIsolation.test.js

@@ -103,7 +103,18 @@ function deferred() {
     return { promise, resolve };
 }
 
+// While an approval is pending, the background starts a 20-second timer to
+// keep itself running. The timer is stubbed and never starts, so no test in
+// this file leaves it running.
+let keepRunningTimer;
+beforeEach(() => {
+    keepRunningTimer = jest
+        .spyOn(global, "setInterval")
+        .mockImplementation(() => 1);
+});
+
 afterEach(() => {
+    keepRunningTimer.mockRestore();
     delete global.chrome;
 });
 

tests/balanceRefreshNetworkSwitch.test.js

@@ -6,6 +6,10 @@
 // approved a site's request, which changes only the stored record. Driven
 // through the real popup over a stored profile on Ethereum Mainnet. The same
 // refresh in the background is in tests/backgroundStateIsolation.test.js.
+//
+// The last test covers a balance refresh by the background that is saved while
+// a switch in Settings waits for the lock
+// (https://git.eeqj.de/sneak/AutistMask/issues/653).
 
 const {
     bootPopup,
@@ -159,3 +163,50 @@ test("a refresh that returns after the background switched the network writes no
 
     expectNothingStored(page);
 });
+
+// The background's refresh saves Ethereum Mainnet's balances while the switch
+// in Settings waits for the lock. This page last saved a balance of "0" and no
+// token balances, the values that the switch sets.
+test("a background refresh saved while a switch in Settings waits for the lock leaves none of its balances stored", async () => {
+    const profile = unversionedValidProfile();
+    profile.wallets[0].addresses[0].balance = "0";
+    const page = await bootPopup(profile);
+    expect(page.pageErrors).toEqual([]);
+    const background = require("../src/background/state");
+    await page.click("btn-settings");
+
+    // The background takes the lock first and holds it until the test calls
+    // `letGo()`. It then saves balances as backgroundRefresh() in
+    // src/background/index.js does.
+    let letGo;
+    const refreshSave = background.updateState(async (fresh) => {
+        await new Promise((resolve) => {
+            letGo = resolve;
+        });
+        fresh.wallets[0].addresses[0].balance = "7.0";
+        fresh.wallets[0].addresses[0].tokenBalances = [
+            {
+                address: TOKEN_ADDRESS,
+                name: "Test Token",
+                symbol: "TST",
+                decimals: 18,
+                balance: "5.0",
+                holders: null,
+            },
+        ];
+        fresh.lastBalanceRefresh = Date.now();
+    });
+    await page.settle();
+
+    const select = page.node("settings-network");
+    select.value = "sepolia";
+    const switching = Promise.all(select.listeners.change.map((fn) => fn()));
+    await page.settle();
+
+    letGo();
+    await refreshSave;
+    await switching;
+    await page.settle();
+
+    expectNothingStored(page);
+});

tests/chainSwitchGate.test.js

@@ -56,7 +56,18 @@ async function settle() {
     for (let i = 0; i < 50; i++) await Promise.resolve();
 }
 
+// While an approval is pending, the background starts a 20-second timer to
+// keep itself running. The timer is stubbed and never starts, so no test in
+// this file leaves it running.
+let keepRunningTimer;
+beforeEach(() => {
+    keepRunningTimer = jest
+        .spyOn(global, "setInterval")
+        .mockImplementation(() => 1);
+});
+
 afterEach(() => {
+    keepRunningTimer.mockRestore();
     delete global.chrome;
 });
 

tests/coldWorkerChainSwitch.test.js

@@ -64,7 +64,18 @@ async function settle() {
     for (let i = 0; i < 50; i++) await Promise.resolve();
 }
 
+// While an approval is pending, the background starts a 20-second timer to
+// keep itself running. The timer is stubbed and never starts, so no test in
+// this file leaves it running.
+let keepRunningTimer;
+beforeEach(() => {
+    keepRunningTimer = jest
+        .spyOn(global, "setInterval")
+        .mockImplementation(() => 1);
+});
+
 afterEach(() => {
+    keepRunningTimer.mockRestore();
     delete global.chrome;
 });
 

tests/coldWorkerSendTransaction.test.js

@@ -76,7 +76,18 @@ async function settle() {
     for (let i = 0; i < 60; i++) await Promise.resolve();
 }
 
+// While an approval is pending, the background starts a 20-second timer to
+// keep itself running. The timer is stubbed and never starts, so no test in
+// this file leaves it running.
+let keepRunningTimer;
+beforeEach(() => {
+    keepRunningTimer = jest
+        .spyOn(global, "setInterval")
+        .mockImplementation(() => 1);
+});
+
 afterEach(() => {
+    keepRunningTimer.mockRestore();
     delete global.chrome;
 });
 

tests/connectedSitesWorkerRestart.test.js

@@ -57,7 +57,18 @@ async function settle() {
     for (let i = 0; i < 50; i++) await Promise.resolve();
 }
 
+// While an approval is pending, the background starts a 20-second timer to
+// keep itself running. The timer is stubbed and never starts, so no test in
+// this file leaves it running.
+let keepRunningTimer;
+beforeEach(() => {
+    keepRunningTimer = jest
+        .spyOn(global, "setInterval")
+        .mockImplementation(() => 1);
+});
+
 afterEach(() => {
+    keepRunningTimer.mockRestore();
     delete global.chrome;
     jest.resetModules();
 });

tests/deleteWalletLostPassword.test.js

@@ -102,6 +102,17 @@ function makeDocument() {
 
 // ------------------------------------------------------------ harness
 
+// showFlash() starts a timer that clears the message two seconds later. Each
+// test here runs on fake timers and drops them in afterEach, so that timer
+// never outlives the test.
+beforeEach(() => {
+    jest.useFakeTimers();
+});
+
+afterEach(() => {
+    jest.useRealTimers();
+});
+
 function wallet(name, secret, addresses) {
     return {
         type: "hd",

tests/historyAfterNetworkSwitch.test.js

@@ -0,0 +1,498 @@
+// Home, AddressDetail and AddressToken drop a transaction history answer that
+// lands after a network switch. A dropped answer draws no rows and saves no
+// fraud contracts (https://git.eeqj.de/sneak/AutistMask/issues/657).
+//
+// Most tests hold the history request open, switch the network or what the
+// screen shows, and then let the answer land. The views run against a minimal
+// DOM stub, as in tests/transactionListCancelled.test.js, and over
+// tests/support/storageStub.js.
+
+const { makeStorageStub } = require("./support/storageStub");
+const { STATE_SCHEMA_VERSION } = require("../src/shared/stateSchema");
+
+jest.mock("../src/shared/transactions", () => ({
+    ...jest.requireActual("../src/shared/transactions"),
+    fetchRecentTransactions: jest.fn(async () => []),
+}));
+jest.mock("../src/shared/ens", () => ({
+    resolveEnsNames: jest.fn(async () => new Map()),
+}));
+
+const { fetchRecentTransactions } = require("../src/shared/transactions");
+const { resolveEnsNames } = require("../src/shared/ens");
+const { state, loadState } = require("../src/shared/state");
+const { onChainSwitch } = require("../src/shared/chainSwitch");
+const { applyChainSwitchFields } = require("../src/shared/chainSwitchFields");
+const { storedNetworkIs } = require("../src/shared/storedSettings");
+const home = require("../src/popup/views/home");
+const addressDetail = require("../src/popup/views/addressDetail");
+const addressToken = require("../src/popup/views/addressToken");
+
+const ADDRESS = "0x1111111111111111111111111111111111111111";
+const OTHER_ADDRESS = "0x2222222222222222222222222222222222222222";
+const RECIPIENT = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
+// A contract that sends a token claiming USDT's symbol. Spotting the spoof
+// adds this contract to the fraud contracts.
+const SPOOF_CONTRACT = "0x3333333333333333333333333333333333333333";
+const TOKEN = "0x6B175474E89094C44Da98b954EedeAC495271d0F";
+
+// A profile on Ethereum Mainnet with two addresses, "Use Blockscout" on and no
+// fraud contracts.
+function profile() {
+    return {
+        schemaVersion: STATE_SCHEMA_VERSION,
+        hasWallet: true,
+        wallets: [
+            {
+                type: "hd",
+                name: "Main",
+                xpub: "xpub-main",
+                encryptedSecret: "encrypted-secret",
+                nextIndex: 2,
+                addresses: [
+                    { address: ADDRESS, balance: "1.0", tokenBalances: [] },
+                    {
+                        address: OTHER_ADDRESS,
+                        balance: "0.0",
+                        tokenBalances: [],
+                    },
+                ],
+            },
+        ],
+        activeAddress: ADDRESS,
+        networkId: "mainnet",
+        rpcUrl: "https://ethereum-rpc.publicnode.com",
+        blockscoutUrl: "https://eth.blockscout.com/api/v2",
+        useBlockscout: true,
+        fraudContracts: [],
+    };
+}
+
+// What Blockscout answers for ADDRESS on Ethereum Mainnet:
+//
+// - a transfer of ETH from ADDRESS;
+// - a transfer of the fake USDT from SPOOF_CONTRACT.
+function history() {
+    return [
+        {
+            hash: "0x85215772ed26ea8b39c2b3b18779030487efbe0b5fd7e882592b2f62b837be84",
+            blockNumber: 2,
+            from: ADDRESS,
+            to: RECIPIENT,
+            value: "1.0000",
+            exactValue: "1.0",
+            rawAmount: "1000000000000000000",
+            rawUnit: "wei",
+            symbol: "ETH",
+            timestamp: 1790000000,
+            isError: false,
+            directionLabel: "Sent",
+            direction: "sent",
+            contractAddress: null,
+        },
+        {
+            hash: "0x0d6a6e0a0d1b7d4c3b2a19087f6e5d4c3b2a19087f6e5d4c3b2a19087f6e5d4c",
+            blockNumber: 1,
+            from: SPOOF_CONTRACT,
+            to: ADDRESS,
+            value: "100.0000",
+            exactValue: "100.0",
+            rawAmount: "100000000",
+            rawUnit: "base units",
+            symbol: "USDT",
+            timestamp: 1790000000,
+            isError: false,
+            directionLabel: "Received",
+            direction: "received",
+            contractAddress: SPOOF_CONTRACT,
+        },
+    ];
+}
+
+// The next history request waits until the returned function is called, and
+// then answers with `answer`.
+function holdHistory(answer = history()) {
+    let land;
+    fetchRecentTransactions.mockImplementationOnce(
+        () =>
+            new Promise((resolve) => {
+                land = () => resolve(answer);
+            }),
+    );
+    return () => land();
+}
+
+// The next history request waits until the returned function is called, and
+// then fails.
+function holdFailure() {
+    let fail;
+    fetchRecentTransactions.mockImplementationOnce(
+        () =>
+            new Promise((resolve, reject) => {
+                fail = () => reject(new Error("Blockscout is down"));
+            }),
+    );
+    return () => fail();
+}
+
+// Another write holds the lock until the returned function is called. Every
+// save waits until then.
+function holdLock() {
+    let release;
+    const held = navigator.locks.request(
+        "autistmask",
+        () =>
+            new Promise((resolve) => {
+                release = resolve;
+            }),
+    );
+    return async () => {
+        release();
+        await held;
+    };
+}
+
+function makeElement(id) {
+    const el = {
+        id,
+        textContent: "",
+        value: "",
+        innerHTML: "",
+        style: {},
+        dataset: {},
+        classList: {
+            add: () => {},
+            remove: () => {},
+            contains: () => false,
+            toggle: () => false,
+        },
+        addEventListener: () => {},
+        querySelectorAll: () => [],
+        appendChild: () => {},
+    };
+    // Views reach for .parentElement to hide whole sections.
+    Object.defineProperty(el, "parentElement", {
+        get: () => node(id + "-parent"),
+    });
+    return el;
+}
+
+function makeDocument() {
+    const els = new Map();
+    return {
+        getElementById(id) {
+            // The debug banner is created on demand by helpers.js; absent
+            // is the state a non-debug, 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"),
+        addEventListener: () => {},
+        body: { prepend: () => {} },
+    };
+}
+
+function node(id) {
+    return globalThis.document.getElementById(id);
+}
+
+// Lets every promise that is not held open settle.
+function settle() {
+    return new Promise((resolve) => setTimeout(resolve, 0));
+}
+
+let storage;
+
+beforeEach(async () => {
+    storage = makeStorageStub({ autistmask: profile() });
+    globalThis.chrome = {
+        storage: { local: storage.local, onChanged: storage.onChanged },
+    };
+    globalThis.document = makeDocument();
+    globalThis.window = { location: { search: "" } };
+    await loadState();
+    state.viewStack = [];
+    state.selectedWallet = 0;
+    state.selectedAddress = 0;
+    state.selectedToken = "ETH";
+    const ctx = { pageClosed: new AbortController().signal };
+    addressDetail.init(ctx);
+    addressToken.init(ctx);
+});
+
+afterEach(() => {
+    delete globalThis.chrome;
+    delete globalThis.document;
+    delete globalThis.window;
+});
+
+const HOME = {
+    name: "Home",
+    listId: "home-tx-list",
+    open: () => home.render({ pageClosed: new AbortController().signal }),
+};
+const ADDRESS_DETAIL = {
+    name: "AddressDetail",
+    listId: "tx-list",
+    open: () => addressDetail.show(),
+};
+const ADDRESS_TOKEN = {
+    name: "AddressToken",
+    listId: "address-token-tx-list",
+    open: () => addressToken.show(),
+};
+
+// Three ways a test switches the network:
+//
+// - made in Settings: the page and storage have both switched;
+// - saved elsewhere: storage has switched and the page has not;
+// - not yet stored: the page has switched and storage has not.
+const SWITCHES = [
+    {
+        how: "made in Settings",
+        to: (networkId) => onChainSwitch(networkId),
+    },
+    {
+        // Another page or the background stored the switch, and this page has
+        // not followed it yet.
+        how: "saved elsewhere",
+        to: async (networkId) => {
+            const record = storage.read("autistmask");
+            applyChainSwitchFields(record, networkId);
+            storage.write("autistmask", record);
+        },
+    },
+    {
+        // The switch's own save has changed the page and has not yet written
+        // storage.
+        how: "not yet stored",
+        to: async (networkId) => {
+            applyChainSwitchFields(state, networkId);
+        },
+    },
+];
+
+// The list still shows `before`, and neither the page nor storage holds a
+// fraud contract.
+function expectNothingAdded(screen, before) {
+    expect(node(screen.listId).innerHTML).toBe(before);
+    expect(state.fraudContracts).toEqual([]);
+    expect(storage.read("autistmask").fraudContracts).toEqual([]);
+}
+
+describe.each([HOME, ADDRESS_DETAIL, ADDRESS_TOKEN])("$name", (screen) => {
+    test("an answer that lands on the same network is drawn and saved", async () => {
+        const land = holdHistory();
+        screen.open();
+        land();
+        await settle();
+
+        expect(node(screen.listId).innerHTML).toContain("tx-row");
+        expect(state.fraudContracts).toEqual([SPOOF_CONTRACT]);
+        expect(storage.read("autistmask").fraudContracts).toEqual([
+            SPOOF_CONTRACT,
+        ]);
+    });
+
+    test.each(SWITCHES)(
+        "an answer that lands after a switch $how adds nothing",
+        async ({ to }) => {
+            const land = holdHistory();
+            screen.open();
+            await settle();
+            const before = node(screen.listId).innerHTML;
+            await to("sepolia");
+            land();
+            await settle();
+
+            expectNothingAdded(screen, before);
+        },
+    );
+
+    // The answer is the transfer of ETH alone, which adds no fraud contract.
+    // Nothing is saved, so only the check before the save can drop the answer.
+    test.each(SWITCHES)(
+        "an answer without a fraud contract that lands after a switch $how adds nothing",
+        async ({ to }) => {
+            const land = holdHistory(history().slice(0, 1));
+            screen.open();
+            await settle();
+            const before = node(screen.listId).innerHTML;
+            await to("sepolia");
+            land();
+            await settle();
+
+            expectNothingAdded(screen, before);
+        },
+    );
+
+    test.each(SWITCHES)(
+        "a request that fails after a switch $how shows no message",
+        async ({ to }) => {
+            const fail = holdFailure();
+            screen.open();
+            await settle();
+            const before = node(screen.listId).innerHTML;
+            await to("sepolia");
+            fail();
+            await settle();
+
+            expect(node(screen.listId).innerHTML).toBe(before);
+        },
+    );
+
+    // The user picks Sepolia in Settings while another write holds the lock.
+    // The answer lands, and its save waits behind the switch.
+    test("an answer whose save waits behind a switch made in Settings adds nothing", async () => {
+        const land = holdHistory();
+        screen.open();
+        const before = node(screen.listId).innerHTML;
+        const releaseLock = holdLock();
+        const switching = onChainSwitch("sepolia");
+        land();
+        await settle();
+        await releaseLock();
+        await switching;
+        await settle();
+
+        expectNothingAdded(screen, before);
+    });
+
+    // The answer lands and its save waits for the lock. Another page or the
+    // background then stores a switch.
+    test("an answer whose save waits while a switch is saved elsewhere adds nothing", async () => {
+        const land = holdHistory();
+        screen.open();
+        const before = node(screen.listId).innerHTML;
+        const releaseLock = holdLock();
+        land();
+        await settle();
+        const record = storage.read("autistmask");
+        applyChainSwitchFields(record, "sepolia");
+        storage.write("autistmask", record);
+        await releaseLock();
+        await settle();
+
+        expectNothingAdded(screen, before);
+    });
+
+    // The answer lands and its save waits for the lock. The page then switches,
+    // and storage has not.
+    test("an answer whose save waits while the page switches adds nothing", async () => {
+        const land = holdHistory();
+        screen.open();
+        const before = node(screen.listId).innerHTML;
+        const releaseLock = holdLock();
+        land();
+        await settle();
+        applyChainSwitchFields(state, "sepolia");
+        await releaseLock();
+        await settle();
+
+        expectNothingAdded(screen, before);
+    });
+
+    test("a request that fails after a switch leaves the new network's rows", async () => {
+        const fail = holdFailure();
+        screen.open();
+        await onChainSwitch("sepolia");
+        fetchRecentTransactions.mockImplementationOnce(async () => history());
+        screen.open();
+        await settle();
+        const drawn = node(screen.listId).innerHTML;
+        fail();
+        await settle();
+
+        expect(drawn).toContain("tx-row");
+        expect(node(screen.listId).innerHTML).toBe(drawn);
+    });
+});
+
+describe.each([ADDRESS_DETAIL, ADDRESS_TOKEN])("$name", (screen) => {
+    test("an answer that lands once the screen shows another address adds nothing", async () => {
+        const land = holdHistory();
+        screen.open();
+        state.selectedAddress = 1;
+        screen.open();
+        await settle();
+        const before = node(screen.listId).innerHTML;
+        land();
+        await settle();
+
+        expectNothingAdded(screen, before);
+    });
+
+    test("a request that fails once the screen shows another address shows no message", async () => {
+        const fail = holdFailure();
+        screen.open();
+        state.selectedAddress = 1;
+        screen.open();
+        await settle();
+        const before = node(screen.listId).innerHTML;
+        fail();
+        await settle();
+
+        expect(node(screen.listId).innerHTML).toBe(before);
+    });
+
+    // The answer is the transfer of ETH alone, which adds no fraud contract.
+    // Nothing is saved, so only the check after the name lookup can drop the
+    // answer.
+    test("an answer whose name lookup lands after a switch adds nothing", async () => {
+        let landNames;
+        resolveEnsNames.mockImplementationOnce(
+            () =>
+                new Promise((resolve) => {
+                    landNames = () => resolve(new Map());
+                }),
+        );
+        fetchRecentTransactions.mockImplementationOnce(async () =>
+            history().slice(0, 1),
+        );
+        screen.open();
+        await settle();
+        const before = node(screen.listId).innerHTML;
+        await onChainSwitch("sepolia");
+        landNames();
+        await settle();
+
+        expectNothingAdded(screen, before);
+    });
+});
+
+test("AddressToken: an answer that lands once the screen shows another token adds nothing", async () => {
+    const land = holdHistory();
+    addressToken.show();
+    state.selectedToken = TOKEN;
+    addressToken.show();
+    await settle();
+    const before = node(ADDRESS_TOKEN.listId).innerHTML;
+    land();
+    await settle();
+
+    expectNothingAdded(ADDRESS_TOKEN, before);
+});
+
+test("AddressToken: a request that fails once the screen shows another token shows no message", async () => {
+    const fail = holdFailure();
+    addressToken.show();
+    state.selectedToken = TOKEN;
+    addressToken.show();
+    await settle();
+    const before = node(ADDRESS_TOKEN.listId).innerHTML;
+    fail();
+    await settle();
+
+    expect(node(ADDRESS_TOKEN.listId).innerHTML).toBe(before);
+});
+
+test("storedNetworkIs(): a failed read counts as no", async () => {
+    globalThis.chrome.storage.local = {
+        get: async () => {
+            throw new Error("storage is down");
+        },
+    };
+
+    await expect(storedNetworkIs("mainnet")).resolves.toBe(false);
+});

tests/popupFollowsNetworkSwitch.test.js

@@ -253,6 +253,271 @@ test("a switch back in Settings after a follow whose write failed is stored", as
     expect(told.at(-1).chainId).toBe(NETWORKS.mainnet.chainId);
 });
 
+// The user saves an endpoint URL in Settings on Ethereum Mainnet. Before the
+// URL is stored, the background saves a switch to Sepolia. Another write holds
+// the lock, so the popup's follow of that switch and the URL's save both wait
+// for the lock. Either may take it first. The URL is stored for neither
+// network. The flash message says that the network changed.
+test.each([
+    { button: "btn-save-rpc", field: "settings-rpc", first: "follow" },
+    { button: "btn-save-rpc", field: "settings-rpc", first: "save" },
+    {
+        button: "btn-save-blockscout",
+        field: "settings-blockscout",
+        first: "follow",
+    },
+    {
+        button: "btn-save-blockscout",
+        field: "settings-blockscout",
+        first: "save",
+    },
+])(
+    "$button saves nothing when the network changes before the URL is stored ($first first)",
+    async ({ button, field, first }) => {
+        const page = await bootOnAddress();
+        await page.click("btn-settings");
+        // This answer passes both endpoint checks. The RPC check reads
+        // Ethereum Mainnet's chain id from it. The Blockscout check reads `ok`.
+        globalThis.fetch.mockResolvedValue({
+            ok: true,
+            json: async () => ({ result: NETWORKS.mainnet.chainId }),
+        });
+        const url = "https://own-node.example.invalid";
+
+        let releaseLock;
+        const lockHeld = navigator.locks.request(
+            "autistmask",
+            () =>
+                new Promise((resolve) => {
+                    releaseLock = resolve;
+                }),
+        );
+        // The click handler runs until its save waits for the lock.
+        const tapSave = async () => {
+            page.node(field).value = url;
+            const saving = page.node(button).listeners.click.map((fn) => fn());
+            await page.settle();
+            return saving;
+        };
+        let saving;
+        if (first === "save") saving = await tapSave();
+        await backgroundSwitch(page, "sepolia");
+        if (first === "follow") saving = await tapSave();
+        releaseLock();
+        await lockHeld;
+        await Promise.all(saving);
+        await page.settle();
+
+        const { state } = require("../src/shared/state");
+        expect(state.networkId).toBe("sepolia");
+        expect(JSON.stringify(page.storage.read("autistmask"))).not.toContain(
+            url,
+        );
+        expect(page.text("flash-msg")).toBe(
+            "The URL was not saved because the network changed.",
+        );
+    },
+);
+
+// The popup's follow of the background's switch to Sepolia has set `state` to
+// Sepolia. The follow's write has not returned yet, so Settings still shows
+// Ethereum Mainnet. The user taps "Save" there. The URL is for Ethereum
+// Mainnet, so the save stores the URL for neither network.
+test.each([
+    { button: "btn-save-rpc", field: "settings-rpc" },
+    { button: "btn-save-blockscout", field: "settings-blockscout" },
+])(
+    "$button saves nothing when tapped while the follow's write waits",
+    async ({ button, field }) => {
+        const page = await bootOnAddress();
+        await page.click("btn-settings");
+        // This answer passes both endpoint checks on Ethereum Mainnet.
+        globalThis.fetch.mockResolvedValue({
+            ok: true,
+            json: async () => ({ result: NETWORKS.mainnet.chainId }),
+        });
+        const url = "https://own-node.example.invalid";
+
+        const { set } = page.storage.local;
+        const write = set.getMockImplementation();
+        let releaseWrite;
+        const writeHeld = new Promise((resolve) => {
+            releaseWrite = resolve;
+        });
+        // The background's write lands; the next, the follow's, waits.
+        set.mockImplementationOnce(write).mockImplementationOnce(
+            async (items) => {
+                await writeHeld;
+                await write(items);
+            },
+        );
+        await backgroundSwitch(page, "sepolia");
+        const { state } = require("../src/shared/state");
+        expect(state.networkId).toBe("sepolia");
+        expect(page.value("settings-network")).toBe("mainnet");
+
+        page.node(field).value = url;
+        const saving = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        releaseWrite();
+        await Promise.all(saving);
+        await page.settle();
+
+        expect(JSON.stringify(page.storage.read("autistmask"))).not.toContain(
+            url,
+        );
+        expect(page.text("flash-msg")).toBe(
+            "The URL was not saved because the network changed.",
+        );
+    },
+);
+
+// The user taps the RPC "Save" on Ethereum Mainnet. While the check waits for
+// the node's answer, the popup follows the background's switch to Sepolia. The
+// node answers with Sepolia's chain id. So the check refuses the node for
+// Ethereum Mainnet, and nothing is stored.
+test("the RPC check compares the answer with the network at the tap", async () => {
+    const page = await bootOnAddress();
+    await page.click("btn-settings");
+    let answer;
+    globalThis.fetch.mockReturnValue(
+        new Promise((resolve) => {
+            answer = resolve;
+        }),
+    );
+    const url = "https://sepolia-node.example.invalid";
+
+    page.node("settings-rpc").value = url;
+    const saving = page.node("btn-save-rpc").listeners.click.map((fn) => fn());
+    await page.settle();
+    await backgroundSwitch(page, "sepolia");
+    const { state } = require("../src/shared/state");
+    expect(state.networkId).toBe("sepolia");
+    answer({ json: async () => ({ result: NETWORKS.sepolia.chainId }) });
+    await Promise.all(saving);
+    await page.settle();
+
+    expect(JSON.stringify(page.storage.read("autistmask"))).not.toContain(url);
+    expect(page.text("flash-msg")).toBe(
+        "Wrong network: expected Ethereum Mainnet.",
+    );
+});
+
+// The user taps the Blockscout "Save" on Ethereum Mainnet. While the check
+// waits for Blockscout's answer, the popup follows the background's switch to
+// Sepolia. The URL is for Ethereum Mainnet, so nothing is stored.
+test("the Blockscout save is for the network at the tap", async () => {
+    const page = await bootOnAddress();
+    await page.click("btn-settings");
+    let answer;
+    globalThis.fetch.mockReturnValue(
+        new Promise((resolve) => {
+            answer = resolve;
+        }),
+    );
+    const url = "https://own-explorer.example.invalid/api/v2";
+
+    page.node("settings-blockscout").value = url;
+    const saving = page
+        .node("btn-save-blockscout")
+        .listeners.click.map((fn) => fn());
+    await page.settle();
+    await backgroundSwitch(page, "sepolia");
+    expect(page.value("settings-network")).toBe("sepolia");
+    answer({ ok: true });
+    await Promise.all(saving);
+    await page.settle();
+
+    expect(JSON.stringify(page.storage.read("autistmask"))).not.toContain(url);
+    expect(page.text("flash-msg")).toBe(
+        "The URL was not saved because the network changed.",
+    );
+});
+
+// Settings is open when the network changes to Sepolia. The popup follows the
+// background's switch, or the user picks Sepolia in the network selector. Each
+// "Save" after the switch stores its URL for Sepolia.
+test.each([
+    ["a follow", (page) => backgroundSwitch(page, "sepolia")],
+    [
+        "the network selector",
+        async (page) => {
+            const select = page.node("settings-network");
+            select.value = "sepolia";
+            for (const fn of select.listeners.change) await fn();
+            await page.settle();
+        },
+    ],
+])(
+    "after a switch to Sepolia by %s, Settings saves each URL for Sepolia",
+    async (_how, switchToSepolia) => {
+        const page = await bootOnAddress();
+        await page.click("btn-settings");
+        await switchToSepolia(page);
+        // This answer passes both endpoint checks on Sepolia. The RPC check
+        // reads Sepolia's chain id from it. The Blockscout check reads `ok`.
+        globalThis.fetch.mockResolvedValue({
+            ok: true,
+            json: async () => ({ result: NETWORKS.sepolia.chainId }),
+        });
+        const rpcUrl = "https://own-node.example.invalid";
+        const blockscoutUrl = "https://own-explorer.example.invalid/api/v2";
+
+        page.node("settings-rpc").value = rpcUrl;
+        await page.click("btn-save-rpc");
+        expect(page.text("flash-msg")).toBe("Saved.");
+        page.node("settings-blockscout").value = blockscoutUrl;
+        await page.click("btn-save-blockscout");
+        expect(page.text("flash-msg")).toBe("Saved.");
+
+        const stored = page.storage.read("autistmask");
+        expect(stored.networkId).toBe("sepolia");
+        expect(stored.rpcUrl).toBe(rpcUrl);
+        expect(stored.blockscoutUrl).toBe(blockscoutUrl);
+    },
+);
+
+// The user picks Sepolia in Settings, but the switch's write fails. The page is
+// then on Sepolia, while Settings was last drawn for Ethereum Mainnet. A "Save"
+// after the failed switch stores nothing for either network.
+test.each([
+    { button: "btn-save-rpc", field: "settings-rpc" },
+    { button: "btn-save-blockscout", field: "settings-blockscout" },
+])(
+    "$button saves nothing after a switch in Settings whose write failed",
+    async ({ button, field }) => {
+        const page = await bootOnAddress();
+        await page.click("btn-settings");
+        page.storage.local.set.mockRejectedValueOnce(
+            new Error("quota exceeded"),
+        );
+        const select = page.node("settings-network");
+        select.value = "sepolia";
+        for (const fn of select.listeners.change) {
+            await expect(fn()).rejects.toThrow("quota exceeded");
+        }
+        await page.settle();
+        const { state } = require("../src/shared/state");
+        expect(state.networkId).toBe("sepolia");
+        // This answer passes both endpoint checks on Ethereum Mainnet.
+        globalThis.fetch.mockResolvedValue({
+            ok: true,
+            json: async () => ({ result: NETWORKS.mainnet.chainId }),
+        });
+        const url = "https://own-node.example.invalid";
+
+        page.node(field).value = url;
+        await page.click(button);
+
+        expect(JSON.stringify(page.storage.read("autistmask"))).not.toContain(
+            url,
+        );
+        expect(page.text("flash-msg")).toBe(
+            "The URL was not saved because the network changed.",
+        );
+    },
+);
+
 // Such as one a newer build wrote, which this build cannot read. Nothing reads
 // or writes the stored record for it: the popup's next save finds it, as
 // before.

tests/refreshDuringRefresh.test.js

@@ -0,0 +1,157 @@
+// While a refresh runs, a request through ctx is not dropped. One more refresh
+// runs once the running one ends, however many were asked for in that time
+// (https://git.eeqj.de/sneak/AutistMask/issues/581). A tick of the ten-second
+// timer that finds a refresh running is dropped. Each test boots the real popup
+// over a stored profile and holds the ten-second refresh open. `readChain()`
+// sets each address's balance from `CHAIN`, as the real `refreshBalances()`
+// sets it from the node.
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+    ADDRESS,
+} = require("./support/popupBoot");
+const {
+    hdWalletFromMnemonic,
+    deriveAddressFromXpub,
+} = require("../src/shared/wallet");
+
+const PHRASE =
+    "abandon abandon abandon abandon abandon abandon " +
+    "abandon abandon abandon abandon abandon about";
+const PASSWORD = "correct horse battery staple";
+
+// The first two addresses of PHRASE, both used on the chain.
+const { xpub, firstAddress } = hdWalletFromMnemonic(PHRASE);
+const SECOND_ADDRESS = deriveAddressFromXpub(xpub, 1);
+
+// The ETH balance the chain holds for each address, in ether.
+const CHAIN = {
+    [ADDRESS]: "1.5",
+    [firstAddress]: "2.0",
+    [SECOND_ADDRESS]: "3.0",
+};
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+// The balance stand-in for a refresh that returns.
+async function readChain(wallets) {
+    for (const wallet of wallets) {
+        for (const addr of wallet.addresses) {
+            addr.balance = CHAIN[addr.address];
+        }
+    }
+}
+
+// Boots the popup over a profile with one wallet. From then on,
+// `refreshBalances()` never returns unless the test answers it. So an unwanted
+// refresh is counted once and then waits, instead of starting more.
+async function boot() {
+    const page = await bootPopup(unversionedValidProfile());
+    expect(page.pageErrors).toEqual([]);
+    const { refreshBalances } = require("../src/shared/balances");
+    refreshBalances.mockImplementation(() => new Promise(() => {}));
+    return { page, refreshBalances };
+}
+
+// Starts the ten-second refresh and holds it open until finish() is called.
+// The held refresh then writes the chain's balances. finish() resolves once
+// the held refresh has saved them and drawn Home. The one refresh after the
+// held one also returns.
+async function holdRefresh(page) {
+    const { refreshBalances } = require("../src/shared/balances");
+    let answer;
+    refreshBalances
+        .mockImplementationOnce(async (wallets) => {
+            await new Promise((resolve) => {
+                answer = resolve;
+            });
+            await readChain(wallets);
+        })
+        .mockImplementationOnce(readChain);
+    const ticking = page.tick();
+    await page.settle();
+    return {
+        finish: async () => {
+            answer();
+            await ticking;
+        },
+    };
+}
+
+// Imports PHRASE on AddWallet. Its address scan finds the phrase's first two
+// addresses.
+async function importPhrase(page) {
+    const { scanForAddresses } = require("../src/shared/balances");
+    scanForAddresses.mockImplementationOnce(async () => ({
+        addresses: [
+            { address: firstAddress, index: 0 },
+            { address: SECOND_ADDRESS, index: 1 },
+        ],
+        nextIndex: 2,
+    }));
+    await page.click("btn-add-wallet-bottom");
+    await page.click("tab-mnemonic");
+    page.node("wallet-mnemonic").value = PHRASE;
+    page.node("add-wallet-password").value = PASSWORD;
+    page.node("add-wallet-password-confirm").value = PASSWORD;
+    await page.click("btn-add-wallet-confirm");
+}
+
+// Imports the private key `key` on AddWallet.
+async function importKey(page, key) {
+    await page.click("btn-add-wallet-bottom");
+    await page.click("tab-privkey");
+    page.node("import-private-key").value = key;
+    page.node("add-wallet-password").value = PASSWORD;
+    page.node("add-wallet-password-confirm").value = PASSWORD;
+    await page.click("btn-add-wallet-confirm");
+}
+
+test("addresses that an import finds during a refresh show their balances once one more refresh returns", async () => {
+    const { page } = await boot();
+    const refresh = await holdRefresh(page);
+
+    await importPhrase(page);
+    expect(page.visibleViews()).toEqual(["main"]);
+    expect(page.text("flash-msg")).toBe("Found 2 addresses.");
+
+    await refresh.finish();
+    await page.settle();
+
+    const list = page.node("wallet-list").innerHTML;
+    expect(list).toContain("<span>2.0000</span>");
+    expect(list).toContain("<span>3.0000</span>");
+});
+
+test("several requests during a refresh lead to exactly one more refresh", async () => {
+    const { page, refreshBalances } = await boot();
+    const refresh = await holdRefresh(page);
+    const calls = refreshBalances.mock.calls.length;
+
+    await importKey(page, "0x" + "11".repeat(32));
+    await importKey(page, "0x" + "22".repeat(32));
+    await importPhrase(page);
+    expect(refreshBalances).toHaveBeenCalledTimes(calls);
+
+    await refresh.finish();
+    await page.settle();
+
+    expect(refreshBalances).toHaveBeenCalledTimes(calls + 1);
+});
+
+test("a tick of the ten-second timer during a refresh starts no other refresh", async () => {
+    const { page, refreshBalances } = await boot();
+    const refresh = await holdRefresh(page);
+    const calls = refreshBalances.mock.calls.length;
+
+    await page.tick();
+
+    await refresh.finish();
+    await page.settle();
+
+    expect(refreshBalances).toHaveBeenCalledTimes(calls);
+});

tests/sendAmountRule.test.js

@@ -131,10 +131,14 @@ async function review(amount, token) {
 async function confirm(amount, token) {
     const txInfo = await review("0.5", token);
     confirmTx.show({ ...txInfo, amount });
-    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+    for (let i = 0; i < 10; i++) await jest.advanceTimersByTimeAsync(0);
 }
 
+// showFlash() starts a timer that clears the message two seconds later. Each
+// test here runs on fake timers and drops them in afterEach, so that timer
+// never outlives the test.
 beforeEach(() => {
+    jest.useFakeTimers();
     elements.clear();
     state.wallets = [
         {
@@ -167,6 +171,10 @@ beforeEach(() => {
     state.currentView = null;
 });
 
+afterEach(() => {
+    jest.useRealTimers();
+});
+
 describe.each([
     ["1e-3", "ETH"],
     ["1e-3", "TOK"],

tests/sendMax.test.js

@@ -277,14 +277,18 @@ async function review() {
 
 // show() starts the fee estimate without awaiting it; this lets it settle.
 async function settle() {
-    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+    for (let i = 0; i < 10; i++) await jest.advanceTimersByTimeAsync(0);
 }
 
 function canSend() {
     return !el("btn-confirm-send").disabled;
 }
 
+// showFlash() starts a timer that clears the message two seconds later. Each
+// test here runs on fake timers and drops them in afterEach, so that timer
+// never outlives the test.
 beforeEach(() => {
+    jest.useFakeTimers();
     elements.clear();
     log.errorf.mockClear();
     pageClosed = new AbortController();
@@ -297,6 +301,10 @@ beforeEach(() => {
     mockNode.broadcast = [];
 });
 
+afterEach(() => {
+    jest.useRealTimers();
+});
+
 describe("Max on an ETH send", () => {
     test("fills in the exact balance minus the fee reserve", async () => {
         await refreshWith(BALANCE_WEI);

tests/settingsEndpointSave.test.js

@@ -0,0 +1,438 @@
+// Another page stores a different RPC or Blockscout URL for the same network.
+// Then the user taps "Save" in Settings on this page, on the URL that this page
+// loaded. The URL on screen is stored, and the flash message reads "Saved."
+// (https://git.eeqj.de/sneak/AutistMask/issues/688). Driven through the real
+// popup over a stored profile on Ethereum Mainnet.
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+} = require("./support/popupBoot");
+const { NETWORKS } = require("../src/shared/networks");
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+test.each([
+    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+    },
+])(
+    "$button stores the URL on screen after another page stored a different one",
+    async ({ button, input, field }) => {
+        const page = await bootPopup(unversionedValidProfile());
+        await page.click("btn-settings");
+        const url = page.value(input);
+        // This write sends this page no storage change event.
+        page.storage.write("autistmask", {
+            ...page.storage.read("autistmask"),
+            [field]: "https://other-page.example.invalid",
+        });
+        // This answer passes both endpoint checks on Ethereum Mainnet. The RPC
+        // check reads Ethereum Mainnet's chain id from it. The Blockscout check
+        // reads `ok`.
+        globalThis.fetch.mockResolvedValue({
+            ok: true,
+            json: async () => ({ result: NETWORKS.mainnet.chainId }),
+        });
+
+        await page.click(button);
+
+        expect(page.storage.read("autistmask")[field]).toBe(url);
+        expect(page.text("flash-msg")).toBe("Saved.");
+    },
+);
+
+// The user types a URL in Settings and taps "Save". While the check waits for
+// the endpoint's answer, another page turns "Use Blockscout" on. This page
+// follows that change and draws Settings again, with the stored URL in the
+// input. The check then passes. The typed URL is not stored. The flash message
+// says that the URL was changed during the check
+// (https://git.eeqj.de/sneak/AutistMask/issues/695).
+test.each([
+    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+    },
+])(
+    "$button stores nothing when Settings is drawn again during the check",
+    async ({ button, input, field }) => {
+        const page = await bootPopup(unversionedValidProfile());
+        await page.click("btn-settings");
+        const storedUrl = page.value(input);
+        let answer;
+        globalThis.fetch.mockReturnValue(
+            new Promise((resolve) => {
+                answer = resolve;
+            }),
+        );
+
+        page.node(input).value = "https://typed.example.invalid";
+        const saving = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        // The browser announces this write to this page.
+        await page.storage.local.set({
+            autistmask: {
+                ...page.storage.read("autistmask"),
+                useBlockscout: true,
+            },
+        });
+        await page.settle();
+        expect(page.node("settings-use-blockscout").checked).toBe(true);
+        // This answer passes both endpoint checks on Ethereum Mainnet.
+        answer({
+            ok: true,
+            json: async () => ({ result: NETWORKS.mainnet.chainId }),
+        });
+        await Promise.all(saving);
+        await page.settle();
+
+        expect(page.storage.read("autistmask")[field]).toBe(storedUrl);
+        expect(page.value(input)).toBe(storedUrl);
+        expect(page.text("flash-msg")).toBe(
+            "The URL was not saved because it was changed during the check.",
+        );
+    },
+);
+
+// As above, but another write holds the lock. So this page's follow of the
+// change to "Use Blockscout" waits for the lock. The endpoint answers while the
+// input still shows the typed URL. The save then asks for the lock, after the
+// follow did. So the follow draws Settings again before the save compares the
+// input.
+test.each([
+    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+    },
+])(
+    "$button stores nothing when Settings is drawn again while the save waits for the lock",
+    async ({ button, input, field }) => {
+        const page = await bootPopup(unversionedValidProfile());
+        await page.click("btn-settings");
+        const storedUrl = page.value(input);
+        let answer;
+        globalThis.fetch.mockReturnValue(
+            new Promise((resolve) => {
+                answer = resolve;
+            }),
+        );
+        const typedUrl = "https://typed.example.invalid";
+
+        page.node(input).value = typedUrl;
+        const saving = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        let releaseLock;
+        const lockHeld = navigator.locks.request(
+            "autistmask",
+            () =>
+                new Promise((resolve) => {
+                    releaseLock = resolve;
+                }),
+        );
+        // The browser announces this write to this page.
+        await page.storage.local.set({
+            autistmask: {
+                ...page.storage.read("autistmask"),
+                useBlockscout: true,
+            },
+        });
+        await page.settle();
+        // This answer passes both endpoint checks on Ethereum Mainnet.
+        answer({
+            ok: true,
+            json: async () => ({ result: NETWORKS.mainnet.chainId }),
+        });
+        await page.settle();
+        expect(page.value(input)).toBe(typedUrl);
+        releaseLock();
+        await lockHeld;
+        await Promise.all(saving);
+        await page.settle();
+
+        expect(page.node("settings-use-blockscout").checked).toBe(true);
+        expect(page.storage.read("autistmask")[field]).toBe(storedUrl);
+        expect(page.value(input)).toBe(storedUrl);
+        expect(page.text("flash-msg")).toBe(
+            "The URL was not saved because it was changed during the check.",
+        );
+    },
+);
+
+// This answer passes both endpoint checks on Ethereum Mainnet.
+const PASSING_ANSWER = {
+    ok: true,
+    json: async () => ({ result: NETWORKS.mainnet.chainId }),
+};
+
+// Both endpoint checks read this answer as an error. The RPC check reads the
+// answer's `error`. The Blockscout check reads the answer's `ok`.
+const ERROR_ANSWER = {
+    ok: false,
+    status: 500,
+    json: async () => ({ error: { code: -32603, message: "Internal error" } }),
+};
+
+// The user types a URL in Settings and taps "Save". Before the endpoint answers,
+// the user types a second URL and taps "Save" again. The second check passes
+// first. The second URL is stored, and the flash message reads "Saved.". The
+// first check then ends in one of three ways:
+//
+// - It passes.
+// - It fails, because fetch cannot reach the endpoint.
+// - It gets an answer that holds an error.
+//
+// None of the three changes the stored URL or the flash message
+// (https://git.eeqj.de/sneak/AutistMask/issues/698).
+test.each([
+    {
+        button: "btn-save-rpc",
+        input: "settings-rpc",
+        field: "rpcUrl",
+        first: "passes",
+    },
+    {
+        button: "btn-save-rpc",
+        input: "settings-rpc",
+        field: "rpcUrl",
+        first: "fails",
+    },
+    {
+        button: "btn-save-rpc",
+        input: "settings-rpc",
+        field: "rpcUrl",
+        first: "answers with an error",
+    },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+        first: "passes",
+    },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+        first: "fails",
+    },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+        first: "answers with an error",
+    },
+])(
+    "$button keeps the second tap's result when the first check $first last",
+    async ({ button, input, field, first }) => {
+        const page = await bootPopup(unversionedValidProfile());
+        await page.click("btn-settings");
+        const checks = [];
+        globalThis.fetch.mockImplementation(
+            () =>
+                new Promise((resolve, reject) => {
+                    checks.push({ resolve, reject });
+                }),
+        );
+        const secondUrl = "https://second.example.invalid";
+
+        page.node(input).value = "https://first.example.invalid";
+        const firstTap = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        page.node(input).value = secondUrl;
+        const secondTap = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        checks[1].resolve(PASSING_ANSWER);
+        await Promise.all(secondTap);
+        await page.settle();
+        expect(page.text("flash-msg")).toBe("Saved.");
+        if (first === "passes") {
+            checks[0].resolve(PASSING_ANSWER);
+        } else if (first === "answers with an error") {
+            checks[0].resolve(ERROR_ANSWER);
+        } else {
+            // fetch rejects when it cannot reach the endpoint.
+            checks[0].reject(new TypeError("Failed to fetch"));
+        }
+        await Promise.all(firstTap);
+        await page.settle();
+
+        expect(checks).toHaveLength(2);
+        expect(page.storage.read("autistmask")[field]).toBe(secondUrl);
+        expect(page.text("flash-msg")).toBe("Saved.");
+    },
+);
+
+// The user types a URL in Settings and taps "Save". Before the endpoint answers,
+// the user empties the input and taps "Save" again. The flash message asks for
+// a URL. The first check then passes. The flash message still asks for a URL,
+// and the stored URL is unchanged.
+test.each([
+    {
+        button: "btn-save-rpc",
+        input: "settings-rpc",
+        field: "rpcUrl",
+        message: "Please enter an RPC URL.",
+    },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+        message: "Please enter a Blockscout API URL.",
+    },
+])(
+    "$button keeps the empty-input message when the first check passes last",
+    async ({ button, input, field, message }) => {
+        const page = await bootPopup(unversionedValidProfile());
+        await page.click("btn-settings");
+        const storedUrl = page.value(input);
+        let answer;
+        globalThis.fetch.mockReturnValue(
+            new Promise((resolve) => {
+                answer = resolve;
+            }),
+        );
+
+        page.node(input).value = "https://typed.example.invalid";
+        const firstTap = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        page.node(input).value = "";
+        await page.click(button);
+        expect(page.text("flash-msg")).toBe(message);
+        answer(PASSING_ANSWER);
+        await Promise.all(firstTap);
+        await page.settle();
+
+        expect(page.storage.read("autistmask")[field]).toBe(storedUrl);
+        expect(page.text("flash-msg")).toBe(message);
+    },
+);
+
+// The user types a URL in Settings and taps "Save". Another write holds the
+// lock. So the save waits for the lock once the check passes. The user then
+// taps "Save" again on the same URL. When the lock is free, the first save
+// stores nothing and shows no flash message. The second check then passes, and
+// the second save stores the URL.
+test.each([
+    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+    },
+])(
+    "$button stores nothing for an earlier tap still waiting for the lock",
+    async ({ button, input, field }) => {
+        const page = await bootPopup(unversionedValidProfile());
+        await page.click("btn-settings");
+        const storedUrl = page.value(input);
+        const checks = [];
+        globalThis.fetch.mockImplementation(
+            () =>
+                new Promise((resolve) => {
+                    checks.push(resolve);
+                }),
+        );
+        const typedUrl = "https://typed.example.invalid";
+
+        page.node(input).value = typedUrl;
+        const firstTap = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        let releaseLock;
+        const lockHeld = navigator.locks.request(
+            "autistmask",
+            () =>
+                new Promise((resolve) => {
+                    releaseLock = resolve;
+                }),
+        );
+        checks[0](PASSING_ANSWER);
+        await page.settle();
+        const secondTap = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        releaseLock();
+        await lockHeld;
+        await Promise.all(firstTap);
+        await page.settle();
+
+        expect(page.storage.read("autistmask")[field]).toBe(storedUrl);
+        expect(page.text("flash-msg")).toBe("Testing endpoint...");
+
+        checks[1](PASSING_ANSWER);
+        await Promise.all(secondTap);
+        await page.settle();
+
+        expect(checks).toHaveLength(2);
+        expect(page.storage.read("autistmask")[field]).toBe(typedUrl);
+        expect(page.text("flash-msg")).toBe("Saved.");
+    },
+);
+
+// The user taps "Save", and the check passes. The save then begins its storage
+// write, and this test keeps the write waiting. The user taps "Save" again, and
+// the second check cannot reach the endpoint. When the write ends, the flash
+// message still reads "Could not reach endpoint.". The write stores the URL
+// anyway, because the write began before the second tap.
+test.each([
+    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+    },
+])(
+    "$button keeps the second tap's message when tapped again during the write",
+    async ({ button, input, field }) => {
+        const page = await bootPopup(unversionedValidProfile());
+        await page.click("btn-settings");
+        const checks = [];
+        globalThis.fetch.mockImplementation(
+            () =>
+                new Promise((resolve, reject) => {
+                    checks.push({ resolve, reject });
+                }),
+        );
+        const typedUrl = "https://typed.example.invalid";
+
+        page.node(input).value = typedUrl;
+        const firstTap = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        const { set } = page.storage.local;
+        const write = set.getMockImplementation();
+        let writeBegan = false;
+        let releaseWrite;
+        const writeHeld = new Promise((resolve) => {
+            releaseWrite = resolve;
+        });
+        set.mockImplementationOnce(async (items) => {
+            writeBegan = true;
+            await writeHeld;
+            await write(items);
+        });
+        checks[0].resolve(PASSING_ANSWER);
+        await page.settle();
+        expect(writeBegan).toBe(true);
+        const secondTap = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        // fetch rejects when it cannot reach the endpoint.
+        checks[1].reject(new TypeError("Failed to fetch"));
+        await Promise.all(secondTap);
+        await page.settle();
+        expect(page.text("flash-msg")).toBe("Could not reach endpoint.");
+        releaseWrite();
+        await Promise.all(firstTap);
+        await page.settle();
+
+        expect(checks).toHaveLength(2);
+        expect(page.storage.read("autistmask")[field]).toBe(typedUrl);
+        expect(page.text("flash-msg")).toBe("Could not reach endpoint.");
+    },
+);

tests/spoofedTrackedToken.test.js

@@ -0,0 +1,91 @@
+// A token that the spoof rule refuses never shows in the balance list, even
+// tracked at zero balance with "Show tracked tokens with zero balance" on, and
+// the two add-token screens refuse to track one
+// (https://git.eeqj.de/sneak/AutistMask/issues/705). Driven through the real
+// popup over a stored profile.
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+    TOKEN_ADDRESS,
+} = require("./support/popupBoot");
+
+// Claims the symbol of the bundled USDT from another contract.
+const FAKE_USDT = {
+    address: TOKEN_ADDRESS,
+    symbol: "USDT",
+    decimals: 6,
+    name: "Tether USD",
+};
+// A symbol the bundled list does not have, so the spoof rule passes it.
+const TEST_TOKEN = {
+    address: "0xBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB",
+    symbol: "TST",
+    decimals: 18,
+    name: "Test Token",
+};
+const REFUSED_FLASH = "Not added: this token fakes a known symbol.";
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+test("a fake token tracked at zero balance is not listed while zero balances are shown", async () => {
+    const boot = await bootPopup(
+        unversionedValidProfile({
+            currentView: "address",
+            selectedWallet: 0,
+            selectedAddress: 0,
+            trackedTokens: [FAKE_USDT, TEST_TOKEN],
+            showZeroBalanceTokens: true,
+        }),
+    );
+    const rows = boot.node("address-balances").innerHTML;
+    expect(rows).toContain(`data-token="${TEST_TOKEN.address.toLowerCase()}"`);
+    expect(rows).not.toContain(
+        `data-token="${FAKE_USDT.address.toLowerCase()}"`,
+    );
+});
+
+// Each screen is opened from AddressDetail by the buttons named, in order.
+describe.each([
+    [
+        "AddToken",
+        ["btn-add-token"],
+        "add-token",
+        "add-token-address",
+        "btn-add-token-confirm",
+    ],
+    [
+        "SettingsAddToken",
+        ["btn-settings", "btn-settings-add-token"],
+        "settings-addtoken",
+        "settings-addtoken-address",
+        "btn-settings-addtoken-manual",
+    ],
+])("%s", (_, opening, view, field, button) => {
+    test("refuses a fake token by contract address", async () => {
+        const boot = await bootPopup(
+            unversionedValidProfile({
+                currentView: "address",
+                selectedWallet: 0,
+                selectedAddress: 0,
+            }),
+        );
+        for (const id of opening) await boot.click(id);
+        expect(boot.visibleViews()).toEqual([view]);
+        const { lookupTokenInfo } = require("../src/shared/balances");
+        lookupTokenInfo.mockResolvedValueOnce({
+            symbol: FAKE_USDT.symbol,
+            decimals: FAKE_USDT.decimals,
+            name: FAKE_USDT.name,
+        });
+        boot.node(field).value = FAKE_USDT.address;
+
+        await boot.click(button);
+        expect(boot.text("flash-msg")).toBe(REFUSED_FLASH);
+        expect(boot.visibleViews()).toEqual([view]);
+        expect(boot.storage.read("autistmask").trackedTokens).toEqual([]);
+    });
+});

tests/trackedTokensPerNetwork.test.js

@@ -5,6 +5,9 @@
 // a contract lookup that answers after one. Driven through the real popup over
 // a stored profile; the same switch made by the background is in
 // tests/coldWorkerChainSwitch.test.js.
+//
+// The tests of what another page stored before a switch in Settings cover a
+// fraud contract too (https://git.eeqj.de/sneak/AutistMask/issues/692).
 
 const {
     bootPopup,
@@ -177,6 +180,504 @@ test("a token added by contract address on Sepolia is tracked on Sepolia only",
     expect(onSepolia).not.toContain("DAI");
 });
 
+// Another popup page tracks DAI on Ethereum Mainnet after this page's last
+// save. The switch to Sepolia puts DAI away under Ethereum Mainnet.
+test("a token another page tracked before a switch in Settings stays tracked on Ethereum Mainnet", async () => {
+    const boot = await bootPopup(unversionedValidProfile());
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        trackedTokens: [MAINNET_TOKEN],
+    });
+
+    await boot.click("btn-settings");
+    await chooseNetwork(boot, "sepolia");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([MAINNET_TOKEN]);
+});
+
+// Another popup page stops tracking DAI on Ethereum Mainnet after this page's
+// last save. This page still holds DAI. The switch to Sepolia does not store
+// DAI under Ethereum Mainnet again.
+test("a token another page removed before a switch in Settings stays removed", async () => {
+    const boot = await bootPopup(
+        unversionedValidProfile({ trackedTokens: [MAINNET_TOKEN] }),
+    );
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        trackedTokens: [],
+    });
+
+    await boot.click("btn-settings");
+    await chooseNetwork(boot, "sepolia");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([]);
+});
+
+// Another popup page removes DAI after this page's last save. That page then
+// adds DAI again, typing the contract address in lower case. The two pages'
+// entries for DAI match, because contract addresses are compared ignoring
+// letter case. The switch to Sepolia keeps this page's entry under Ethereum
+// Mainnet.
+test("a token another page added again with a lower-case address keeps this page's entry", async () => {
+    const boot = await bootPopup(
+        unversionedValidProfile({ trackedTokens: [MAINNET_TOKEN] }),
+    );
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        trackedTokens: [
+            { ...MAINNET_TOKEN, address: MAINNET_TOKEN.address.toLowerCase() },
+        ],
+    });
+
+    await boot.click("btn-settings");
+    await chooseNetwork(boot, "sepolia");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.networkTrackedTokens.mainnet).toEqual([MAINNET_TOKEN]);
+});
+
+// Another popup page saves a switch to Sepolia after this page's last save.
+// TST is tracked on Sepolia. This page has not taken that switch yet. A switch
+// to Sepolia in this page's Settings keeps TST off Ethereum Mainnet's list.
+test("a token tracked on Sepolia when another page switched there is not tracked on Ethereum Mainnet", async () => {
+    const boot = await bootPopup(unversionedValidProfile());
+    expect(boot.pageErrors).toEqual([]);
+    await boot.click("btn-settings");
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        networkId: "sepolia",
+        trackedTokens: [SEPOLIA_TOKEN],
+    });
+
+    await chooseNetwork(boot, "sepolia");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([SEPOLIA_TOKEN]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([]);
+});
+
+// Another popup page saves a switch to Sepolia, where TST is tracked. Before
+// taking that switch, this page adds a token on Ethereum Mainnet. The add's
+// save adds the token to Ethereum Mainnet's list and leaves Sepolia's list as
+// it was.
+test("a token added before this page takes another page's switch is tracked on Ethereum Mainnet", async () => {
+    const boot = await bootOnAddToken("mainnet", {
+        trackedTokens: [MAINNET_TOKEN],
+        networkTrackedTokens: { sepolia: [SEPOLIA_TOKEN] },
+    });
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        networkId: "sepolia",
+        trackedTokens: [SEPOLIA_TOKEN],
+        networkTrackedTokens: {
+            mainnet: [MAINNET_TOKEN],
+            sepolia: [SEPOLIA_TOKEN],
+        },
+    });
+    const { lookupTokenInfo } = require("../src/shared/balances");
+    lookupTokenInfo.mockResolvedValueOnce({
+        symbol: "NEW",
+        decimals: 18,
+        name: "New Token",
+    });
+
+    boot.node("settings-addtoken-address").value = NEW_TOKEN_ADDRESS;
+    await boot.click("btn-settings-addtoken-manual");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([SEPOLIA_TOKEN]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([
+        MAINNET_TOKEN,
+        {
+            address: NEW_TOKEN_ADDRESS,
+            symbol: "NEW",
+            decimals: 18,
+            name: "New Token",
+        },
+    ]);
+});
+
+// Another popup page tracks DAI on Ethereum Mainnet and then saves a switch to
+// Sepolia. This page does not track DAI. Before taking that switch, this page
+// adds a token on Ethereum Mainnet. The add's save puts both DAI and the new
+// token on Ethereum Mainnet's list.
+test("a token added before this page takes another page's switch joins that page's tokens on Ethereum Mainnet", async () => {
+    const boot = await bootOnAddToken("mainnet");
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        networkId: "sepolia",
+        trackedTokens: [],
+        networkTrackedTokens: { mainnet: [MAINNET_TOKEN] },
+    });
+    const { lookupTokenInfo } = require("../src/shared/balances");
+    lookupTokenInfo.mockResolvedValueOnce({
+        symbol: "NEW",
+        decimals: 18,
+        name: "New Token",
+    });
+
+    boot.node("settings-addtoken-address").value = NEW_TOKEN_ADDRESS;
+    await boot.click("btn-settings-addtoken-manual");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([
+        MAINNET_TOKEN,
+        {
+            address: NEW_TOKEN_ADDRESS,
+            symbol: "NEW",
+            decimals: 18,
+            name: "New Token",
+        },
+    ]);
+});
+
+// Another popup page saves a switch to Sepolia, where TST is tracked. Before
+// taking that switch, this page removes DAI on Ethereum Mainnet, as the `[x]`
+// on a tracked token in Settings does. The removal's save drops DAI from
+// Ethereum Mainnet's list and leaves Sepolia's list as it was.
+test("a token removed before this page takes another page's switch is gone from Ethereum Mainnet", async () => {
+    const boot = await bootPopup(
+        unversionedValidProfile({
+            trackedTokens: [MAINNET_TOKEN],
+            networkTrackedTokens: { sepolia: [SEPOLIA_TOKEN] },
+        }),
+    );
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        networkId: "sepolia",
+        trackedTokens: [SEPOLIA_TOKEN],
+        networkTrackedTokens: {
+            mainnet: [MAINNET_TOKEN],
+            sepolia: [SEPOLIA_TOKEN],
+        },
+    });
+
+    const { state, saveState } = require("../src/shared/state");
+    state.trackedTokens.splice(0, 1);
+    await saveState();
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([SEPOLIA_TOKEN]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([]);
+});
+
+// Another popup page tracks DAI on Ethereum Mainnet and then saves a switch to
+// Sepolia. That switch puts DAI away under Ethereum Mainnet. This page has not
+// taken the switch yet. A switch to Sepolia in this page's Settings keeps DAI
+// on Ethereum Mainnet's list.
+test("a token another page tracked before its own switch stays tracked on Ethereum Mainnet", async () => {
+    const boot = await bootPopup(unversionedValidProfile());
+    expect(boot.pageErrors).toEqual([]);
+    await boot.click("btn-settings");
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        networkId: "sepolia",
+        trackedTokens: [],
+        networkTrackedTokens: { mainnet: [MAINNET_TOKEN] },
+    });
+
+    await chooseNetwork(boot, "sepolia");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.networkTrackedTokens.mainnet).toEqual([MAINNET_TOKEN]);
+});
+
+// This page switches to Sepolia. Another popup page has not taken that switch,
+// and its save adds a token to Ethereum Mainnet's list. This page switches back
+// and tracks that token.
+test("a token another page added on Ethereum Mainnet is tracked when this page switches back there", async () => {
+    const boot = await bootPopup(
+        unversionedValidProfile({ trackedTokens: [MAINNET_TOKEN] }),
+    );
+    expect(boot.pageErrors).toEqual([]);
+    await boot.click("btn-settings");
+    await chooseNetwork(boot, "sepolia");
+    const newToken = {
+        address: NEW_TOKEN_ADDRESS,
+        symbol: "NEW",
+        decimals: 18,
+        name: "New Token",
+    };
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        networkTrackedTokens: { mainnet: [MAINNET_TOKEN, newToken] },
+    });
+
+    await chooseNetwork(boot, "mainnet");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("mainnet");
+    expect(stored.trackedTokens).toEqual([MAINNET_TOKEN, newToken]);
+});
+
+// This page tracks DAI on Ethereum Mainnet and switches to Sepolia. Another
+// popup page has not taken that switch, and its save removes DAI from Ethereum
+// Mainnet's list. This page switches back and does not track DAI again.
+test("a token another page removed on Ethereum Mainnet stays removed when this page switches back there", async () => {
+    const boot = await bootPopup(
+        unversionedValidProfile({ trackedTokens: [MAINNET_TOKEN] }),
+    );
+    expect(boot.pageErrors).toEqual([]);
+    await boot.click("btn-settings");
+    await chooseNetwork(boot, "sepolia");
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        networkTrackedTokens: { mainnet: [] },
+    });
+
+    await chooseNetwork(boot, "mainnet");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("mainnet");
+    expect(stored.trackedTokens).toEqual([]);
+});
+
+// Another popup page records a fraud contract on Ethereum Mainnet after this
+// page's last save. The switch to Sepolia drops that fraud contract, as the
+// switch drops this page's own.
+test("a fraud contract another page recorded before a switch in Settings is not kept on Sepolia", async () => {
+    const boot = await bootPopup(unversionedValidProfile());
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        fraudContracts: [NEW_TOKEN_ADDRESS],
+    });
+
+    await boot.click("btn-settings");
+    await chooseNetwork(boot, "sepolia");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.fraudContracts).toEqual([]);
+});
+
+// The contract lookup on SettingsAddToken answers on Ethereum Mainnet while the
+// switch to Sepolia waits for the lock. The page adds the token to Ethereum
+// Mainnet's list. The switch then keeps that list for Ethereum Mainnet.
+test("a token added while a switch in Settings waits for the lock stays tracked on Ethereum Mainnet", async () => {
+    const boot = await bootOnAddToken("mainnet");
+    expect(boot.pageErrors).toEqual([]);
+    const { lookupTokenInfo } = require("../src/shared/balances");
+    let answer;
+    lookupTokenInfo.mockImplementationOnce(
+        () =>
+            new Promise((resolve) => {
+                answer = resolve;
+            }),
+    );
+    boot.node("settings-addtoken-address").value = NEW_TOKEN_ADDRESS;
+    const adding = boot.click("btn-settings-addtoken-manual");
+    await boot.click("btn-settings");
+
+    // Another write holds the lock, so the switch's save waits for it.
+    let releaseLock;
+    const lockHeld = navigator.locks.request(
+        "autistmask",
+        () =>
+            new Promise((resolve) => {
+                releaseLock = resolve;
+            }),
+    );
+    const select = boot.node("settings-network");
+    select.value = "sepolia";
+    const switching = Promise.all(select.listeners.change.map((fn) => fn()));
+    await boot.settle();
+
+    answer({ symbol: "NEW", decimals: 18, name: "New Token" });
+    await boot.settle();
+    releaseLock();
+    await lockHeld;
+    await switching;
+    await adding;
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([
+        {
+            address: NEW_TOKEN_ADDRESS,
+            symbol: "NEW",
+            decimals: 18,
+            name: "New Token",
+        },
+    ]);
+});
+
+// The contract lookup on SettingsAddToken answers on Ethereum Mainnet while
+// this page's switch to Sepolia waits for the lock. Another popup page holds
+// the lock and stores its own switch to Sepolia, with DAI tracked on Ethereum
+// Mainnet. This page's switch keeps DAI and the new token on Ethereum Mainnet's
+// list.
+test("a token added while a switch in Settings waits for another page's switch stays tracked on Ethereum Mainnet", async () => {
+    const boot = await bootOnAddToken("mainnet");
+    expect(boot.pageErrors).toEqual([]);
+    const { lookupTokenInfo } = require("../src/shared/balances");
+    let answer;
+    lookupTokenInfo.mockImplementationOnce(
+        () =>
+            new Promise((resolve) => {
+                answer = resolve;
+            }),
+    );
+    boot.node("settings-addtoken-address").value = NEW_TOKEN_ADDRESS;
+    const adding = boot.click("btn-settings-addtoken-manual");
+    await boot.click("btn-settings");
+
+    let releaseLock;
+    const lockHeld = navigator.locks.request(
+        "autistmask",
+        () =>
+            new Promise((resolve) => {
+                releaseLock = resolve;
+            }),
+    );
+    const select = boot.node("settings-network");
+    select.value = "sepolia";
+    const switching = Promise.all(select.listeners.change.map((fn) => fn()));
+    await boot.settle();
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        networkId: "sepolia",
+        trackedTokens: [],
+        networkTrackedTokens: { mainnet: [MAINNET_TOKEN] },
+    });
+
+    answer({ symbol: "NEW", decimals: 18, name: "New Token" });
+    await boot.settle();
+    releaseLock();
+    await lockHeld;
+    await switching;
+    await adding;
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([
+        MAINNET_TOKEN,
+        {
+            address: NEW_TOKEN_ADDRESS,
+            symbol: "NEW",
+            decimals: 18,
+            name: "New Token",
+        },
+    ]);
+});
+
+// Another popup page holds the lock and stores its switch to Sepolia, with DAI
+// tracked on Ethereum Mainnet. This page waits for the lock to take that
+// switch. Meanwhile, the contract lookup on SettingsAddToken answers on
+// Ethereum Mainnet. When this page takes that switch, DAI and the new token
+// stay on Ethereum Mainnet's list.
+test("a token added while this page waits to take another page's switch stays tracked on Ethereum Mainnet", async () => {
+    const boot = await bootOnAddToken("mainnet");
+    expect(boot.pageErrors).toEqual([]);
+    let releaseLock;
+    const lockHeld = navigator.locks.request(
+        "autistmask",
+        () =>
+            new Promise((resolve) => {
+                releaseLock = resolve;
+            }),
+    );
+    await boot.storage.local.set({
+        autistmask: {
+            ...boot.storage.read("autistmask"),
+            networkId: "sepolia",
+            trackedTokens: [],
+            networkTrackedTokens: { mainnet: [MAINNET_TOKEN] },
+        },
+    });
+    await boot.settle();
+    const { lookupTokenInfo } = require("../src/shared/balances");
+    lookupTokenInfo.mockResolvedValueOnce({
+        symbol: "NEW",
+        decimals: 18,
+        name: "New Token",
+    });
+
+    boot.node("settings-addtoken-address").value = NEW_TOKEN_ADDRESS;
+    const adding = boot.click("btn-settings-addtoken-manual");
+    await boot.settle();
+    releaseLock();
+    await lockHeld;
+    await adding;
+    await boot.settle();
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([
+        MAINNET_TOKEN,
+        {
+            address: NEW_TOKEN_ADDRESS,
+            symbol: "NEW",
+            decimals: 18,
+            name: "New Token",
+        },
+    ]);
+});
+
+// This page tracks DAI on Ethereum Mainnet. Another popup page holds the lock
+// and stores its switch to Sepolia, with DAI on Ethereum Mainnet's list. This
+// page waits for the lock to take that switch. Meanwhile, the user removes DAI,
+// as the `[x]` on a tracked token in Settings does. When this page takes that
+// switch, DAI is gone from Ethereum Mainnet's list.
+test("a token removed while this page waits to take another page's switch is gone from Ethereum Mainnet", async () => {
+    const boot = await bootPopup(
+        unversionedValidProfile({ trackedTokens: [MAINNET_TOKEN] }),
+    );
+    expect(boot.pageErrors).toEqual([]);
+    let releaseLock;
+    const lockHeld = navigator.locks.request(
+        "autistmask",
+        () =>
+            new Promise((resolve) => {
+                releaseLock = resolve;
+            }),
+    );
+    await boot.storage.local.set({
+        autistmask: {
+            ...boot.storage.read("autistmask"),
+            networkId: "sepolia",
+            trackedTokens: [],
+            networkTrackedTokens: { mainnet: [MAINNET_TOKEN] },
+        },
+    });
+    await boot.settle();
+
+    const { state, saveState } = require("../src/shared/state");
+    state.trackedTokens.splice(0, 1);
+    const removing = saveState();
+    releaseLock();
+    await lockHeld;
+    await removing;
+    await boot.settle();
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([]);
+});
+
 describe("Back after a switch from the Settings gear", () => {
     test("SettingsAddToken no longer offers the common tokens", async () => {
         const boot = await bootOnAddToken("mainnet");

tests/transactionDetailLateAnswer.test.js

@@ -0,0 +1,202 @@
+// TransactionDetail shows only details that Blockscout gave for the
+// transaction on screen (https://git.eeqj.de/sneak/AutistMask/issues/675).
+//
+// The screen asks Blockscout for its transaction and does not wait for the
+// answer. So the user can press Back and open another transaction before
+// Blockscout answers for the first. The first answer must then fill nothing on
+// the second transaction's screen. An answer that lands while Settings is up
+// must still fill TransactionDetail.
+//
+// Driven through the real popup over a stored profile
+// (tests/support/popupBoot.js). Each transaction is opened as a history screen
+// opens it: the current screen is pushed, then transactionDetail.show() draws
+// the transaction.
+
+"use strict";
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+    ADDRESS,
+} = require("./support/popupBoot");
+
+const MAINNET_BLOCKSCOUT = "https://eth.blockscout.com/api/v2";
+const SEPOLIA_BLOCKSCOUT = "https://eth-sepolia.blockscout.com/api/v2";
+const RECIPIENT = "0x2222222222222222222222222222222222222222";
+
+// A history entry for a send of 1 `symbol` from ADDRESS to RECIPIENT, on the
+// network with `chainId`.
+function historyEntry(hash, chainId, symbol) {
+    return {
+        hash,
+        from: ADDRESS,
+        to: RECIPIENT,
+        value: "1.0000",
+        exactValue: "1.0",
+        symbol,
+        timestamp: 1790000000,
+        isError: false,
+        direction: "sent",
+        directionLabel: "Sent",
+        contractAddress: null,
+        chainId,
+    };
+}
+
+const FIRST = historyEntry("0x" + "aa".repeat(32), "0x1", "ETH");
+const SECOND = historyEntry("0x" + "bb".repeat(32), "0x1", "ETH");
+// A transaction on Sepolia with the same hash as FIRST.
+const FIRST_ON_SEPOLIA = historyEntry(FIRST.hash, "0xaa36a7", "SepoliaETH");
+
+// The URL that asks Blockscout for `entry`, on the network it was sent on.
+function requestUrl(entry) {
+    const blockscout =
+        entry.chainId === "0x1" ? MAINNET_BLOCKSCOUT : SEPOLIA_BLOCKSCOUT;
+    return blockscout + "/transactions/" + entry.hash;
+}
+
+// What Blockscout reports for each transaction, by the URL that asks for it.
+const ANSWERS = {
+    [requestUrl(FIRST)]: {
+        block_number: 21000001,
+        nonce: 4441,
+        fee: { value: "21000000000000" },
+        raw_input: "0x11111111",
+        method: "firstMethod",
+    },
+    [requestUrl(SECOND)]: {
+        block_number: 21000002,
+        nonce: 4442,
+        fee: { value: "42000000000000" },
+        raw_input: "0x22222222",
+        method: "secondMethod",
+    },
+    [requestUrl(FIRST_ON_SEPOLIA)]: {
+        block_number: 21000003,
+        nonce: 4443,
+        fee: { value: "63000000000000" },
+        raw_input: "0x33333333",
+        method: "sepoliaMethod",
+    },
+};
+
+// The text each answer puts on screen: its block, nonce, fee, method name and
+// raw data. No text from one answer appears in another.
+const FIRST_SHOWN = [
+    "21000001",
+    "4441",
+    "0.000021 ETH",
+    "firstMethod",
+    "0x11111111",
+];
+const SECOND_SHOWN = [
+    "21000002",
+    "4442",
+    "0.000042 ETH",
+    "secondMethod",
+    "0x22222222",
+];
+const FIRST_ON_SEPOLIA_SHOWN = [
+    "21000003",
+    "4443",
+    "0.000063 SepoliaETH",
+    "sepoliaMethod",
+    "0x33333333",
+];
+
+// Everything drawn in the fields that Blockscout's answer fills.
+function drawnDetails(page) {
+    return [
+        "tx-detail-block",
+        "tx-detail-nonce",
+        "tx-detail-fee",
+        "tx-detail-calldata-action",
+        "tx-detail-rawdata",
+    ]
+        .map((id) => page.node(id).innerHTML + page.node(id).textContent)
+        .join("\n");
+}
+
+// Opens `entry` on TransactionDetail, as a history screen does.
+function open(entry) {
+    require("../src/popup/views/helpers").pushCurrentView();
+    require("../src/popup/views/transactionDetail").show(entry);
+}
+
+// The URLs of every request to Blockscout so far, in order.
+function requestedUrls() {
+    return globalThis.fetch.mock.calls.map(([url]) => url);
+}
+
+// Boots the popup on Home with "Use Blockscout" on. Blockscout answers every
+// request at once from ANSWERS, except the request for `held`. Returns the
+// page and answer(), which lets the answer for `held` land.
+async function bootWithHeldRequest(held) {
+    const page = await bootPopup(
+        unversionedValidProfile({ useBlockscout: true }),
+    );
+    let answer;
+    const heldAnswer = new Promise((resolve) => {
+        answer = resolve;
+    });
+    globalThis.fetch = jest.fn(async (url) => {
+        if (url === requestUrl(held)) await heldAnswer;
+        return { ok: true, status: 200, json: async () => ANSWERS[url] };
+    });
+    return { page, answer: () => answer() };
+}
+
+// The user opens `first`, whose request to Blockscout is held. Then the user
+// presses Back and opens `second`. Then the answer for `first` lands. Returns
+// the page.
+async function firstAnswerLandsOnSecond(first, second) {
+    const { page, answer } = await bootWithHeldRequest(first);
+    open(first);
+    await page.settle();
+    await page.click("btn-tx-back");
+    expect(page.visibleViews()).toEqual(["main"]);
+    open(second);
+    await page.settle();
+    expect(requestedUrls()).toEqual([requestUrl(first), requestUrl(second)]);
+    answer();
+    await page.settle();
+    expect(page.visibleViews()).toEqual(["transaction"]);
+    return page;
+}
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+test("an answer for the first transaction that lands on the second one's screen fills nothing", async () => {
+    const page = await firstAnswerLandsOnSecond(FIRST, SECOND);
+
+    const drawn = drawnDetails(page);
+    for (const text of SECOND_SHOWN) expect(drawn).toContain(text);
+    for (const text of FIRST_SHOWN) expect(drawn).not.toContain(text);
+});
+
+test("an answer for a hash on mainnet that lands on the same hash's screen on Sepolia fills nothing", async () => {
+    const page = await firstAnswerLandsOnSecond(FIRST, FIRST_ON_SEPOLIA);
+
+    const drawn = drawnDetails(page);
+    for (const text of FIRST_ON_SEPOLIA_SHOWN) expect(drawn).toContain(text);
+    for (const text of FIRST_SHOWN) expect(drawn).not.toContain(text);
+});
+
+test("an answer that lands while Settings is up still fills TransactionDetail", async () => {
+    const { page, answer } = await bootWithHeldRequest(FIRST);
+    open(FIRST);
+    await page.settle();
+    await page.click("btn-settings");
+    expect(page.visibleViews()).toEqual(["settings"]);
+    answer();
+    await page.settle();
+    await page.click("btn-settings");
+
+    expect(page.visibleViews()).toEqual(["transaction"]);
+    expect(requestedUrls()).toEqual([requestUrl(FIRST)]);
+    const drawn = drawnDetails(page);
+    for (const text of FIRST_SHOWN) expect(drawn).toContain(text);
+});

tests/uniswap.test.js

@@ -2871,8 +2871,9 @@ describe("uniswap decoder", () => {
                         ...USDT_400_GROUP,
                         ...ONE_USDT_LINES(OTHER_ADDR),
                     ],
-                    // The last swap step's minimum.
-                    minimum: "390.0000 USDC",
+                    // Both swap steps pay USDC to the user, so the minimum
+                    // is the sum of their two minimums.
+                    minimum: "980.0000 USDC",
                 },
             ])(
                 "$kind shows each take's own lines and the allowances, and no Amount figure or Min. received",
@@ -3310,6 +3311,684 @@ describe("uniswap decoder", () => {
 
             expect(detail(result, "Amount").value).toBe("Up to 1000.0000 USDT");
         });
+
+        // https://git.eeqj.de/sneak/AutistMask/issues/660 — Permit2 has no
+        // allowance of ETH, so a permit on the zero address reads as one on a
+        // token nothing knows. On next at 53551c6 such a permit's Allowance
+        // token line read ETH. A permit of 1 wei of the zero address before a
+        // V4 step of 5 ETH made the Amount line read 0.000000000000000001 ETH.
+        // With that permit to another spender and a SETTLE the router pays, no
+        // line gave the 5 ETH.
+        describe("a permit on the zero address", () => {
+            const FIVE_ETH = 5000000000000000000n;
+            // The lines of a permit of `amount` base units of the zero
+            // address for `spender`.
+            const zeroAddressLines = (amount, spender) => [
+                [
+                    "Permit2 allowance",
+                    amount + " base units (decimals unknown)",
+                ],
+                ["Allowance token", ZERO_ADDR],
+                ["Allowance spender", getAddress(spender)],
+            ];
+            // A V4 swap of 5 ETH for USDC. The user pays its SETTLE when
+            // `payerIsUser` is true; otherwise the router pays it from the
+            // transaction's value.
+            const v4FiveEth = (payerIsUser) =>
+                encodeV4Swap(
+                    new Uint8Array([
+                        V4_SWAP_EXACT_IN_SINGLE_ID,
+                        V4_SETTLE_ID,
+                        V4_TAKE_ALL_ID,
+                    ]),
+                    [
+                        encodeV4ExactInSingle(
+                            ZERO_ADDR,
+                            USDC_ADDR,
+                            FIVE_ETH,
+                            1n,
+                        ),
+                        settle(ZERO_ADDR, FIVE_ETH, payerIsUser),
+                        encodeV4TakeAll(USDC_ADDR, 1n),
+                    ],
+                );
+
+            test("a PERMIT2_PERMIT on the zero address names the address", () => {
+                const result = decodeSteps(
+                    [0x00, 0x0a],
+                    [
+                        V3_600,
+                        encodePermit2(
+                            ZERO_ADDR,
+                            1000000000000000000n,
+                            ROUTER_ADDR,
+                        ),
+                    ],
+                );
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "600.0000 USDT"],
+                    ...zeroAddressLines("1000000000000000000", ROUTER_ADDR),
+                ]);
+                expect(detail(result, "Allowance token").address).toBe(
+                    ZERO_ADDR,
+                );
+            });
+
+            test("a PERMIT2_PERMIT_BATCH entry on the zero address names the address", () => {
+                const result = decodeSteps(
+                    [0x03, 0x00],
+                    [
+                        encodePermit2Batch(
+                            [
+                                [USDT_ADDR, USDT_600],
+                                [ZERO_ADDR, 1000000000000000000n],
+                            ],
+                            ROUTER_ADDR,
+                        ),
+                        V3_600,
+                    ],
+                );
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "600.0000 USDT"],
+                    ...USDT_600_LINES,
+                    ...zeroAddressLines("1000000000000000000", ROUTER_ADDR),
+                ]);
+            });
+
+            test("a PERMIT2_PERMIT of 1 wei of the zero address, then a V4 step of 5 ETH the user settles, shows the 5 ETH", () => {
+                const result = decodeSteps(
+                    [0x0a, 0x10],
+                    [
+                        encodePermit2(ZERO_ADDR, 1n, ROUTER_ADDR),
+                        v4FiveEth(true),
+                    ],
+                );
+                expect(detail(result, "Token In").value).toBe("ETH (native)");
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "5.0000 ETH"],
+                    ...zeroAddressLines("1", ROUTER_ADDR),
+                ]);
+            });
+
+            test("a PERMIT2_PERMIT of 1 wei of the zero address to another spender, then a V4 step of 5 ETH the router settles, shows the 5 ETH", () => {
+                const result = decodeSteps(
+                    [0x0a, 0x10],
+                    [
+                        encodePermit2(ZERO_ADDR, 1n, OTHER_ADDR),
+                        v4FiveEth(false),
+                    ],
+                );
+                expect(detail(result, "Token In").value).toBe("ETH (native)");
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "5.0000 ETH"],
+                    ...zeroAddressLines("1", OTHER_ADDR),
+                ]);
+            });
+
+            test("a PERMIT2_PERMIT_BATCH entry of 1 wei of the zero address to another spender, then a V4 step of 5 ETH the router settles, shows the 5 ETH", () => {
+                const result = decodeSteps(
+                    [0x03, 0x10],
+                    [
+                        encodePermit2Batch([[ZERO_ADDR, 1n]], OTHER_ADDR),
+                        v4FiveEth(false),
+                    ],
+                );
+                expect(detail(result, "Token In").value).toBe("ETH (native)");
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "5.0000 ETH"],
+                    ...zeroAddressLines("1", OTHER_ADDR),
+                ]);
+            });
+        });
+
+        // https://git.eeqj.de/sneak/AutistMask/issues/685 — Permit2 moves no
+        // ETH, so a PERMIT2_TRANSFER_FROM of the zero address reads as a move
+        // of a token nothing knows. On next at ec6b6b5 its lines read ETH,
+        // with an ETH figure.
+        describe("a PERMIT2_TRANSFER_FROM of the zero address", () => {
+            const MOVED_AMOUNT =
+                "1000000000000000000 base units (decimals unknown)";
+
+            test("to another address names the address", () => {
+                const result = decodeSteps(
+                    [0x00, 0x02],
+                    [V3_600, transfer(ZERO_ADDR, OTHER_ADDR, ONE_WETH)],
+                );
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "600.0000 USDT"],
+                    ["Moved from the sender", MOVED_AMOUNT],
+                    ["Token moved", ZERO_ADDR],
+                    ["Moved to", OTHER_ADDR],
+                ]);
+                expect(detail(result, "Token moved").address).toBe(ZERO_ADDR);
+            });
+
+            test("into the router names the address", () => {
+                const result = decodeSteps(
+                    [0x02, 0x00],
+                    [transfer(ZERO_ADDR, ROUTER_ADDR, ONE_WETH), V3_600],
+                );
+                expect(detail(result, "Paid to").value).toBe(
+                    "The router, " +
+                        MOVED_AMOUNT +
+                        " from the sender (later steps may not spend all of it)",
+                );
+                expect(detail(result, "Token moved into the router")).toEqual({
+                    label: "Token moved into the router",
+                    value: ZERO_ADDR,
+                    address: ZERO_ADDR,
+                    isToken: true,
+                });
+            });
+
+            // The V4 step's SETTLE names the user as payer and states no
+            // amount. The step's lines say that the ETH amount is not known.
+            test("after a V4 exact-out step of ETH, also shows that the ETH amount is not known", () => {
+                const v4EthExactOut = encodeV4Swap(
+                    new Uint8Array([
+                        V4_SWAP_EXACT_OUT_SINGLE_ID,
+                        V4_SETTLE_ID,
+                        V4_TAKE_ALL_ID,
+                    ]),
+                    [
+                        encodeV4ExactOutSingle(
+                            ZERO_ADDR,
+                            USDC_ADDR,
+                            590000000n,
+                            ONE_WETH,
+                        ),
+                        encodeV4Settle(ZERO_ADDR),
+                        encodeV4TakeAll(USDC_ADDR, 0n),
+                    ],
+                );
+                const result = decodeSteps(
+                    [0x10, 0x02],
+                    [v4EthExactOut, transfer(ZERO_ADDR, OTHER_ADDR, ONE_WETH)],
+                );
+                expect(detail(result, "Token In").value).toBe("ETH (native)");
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Moved from the sender", UNDECODED],
+                    ["Token moved", "ETH"],
+                    ["Moved to", "The swap step that spends it"],
+                    ["Moved from the sender", MOVED_AMOUNT],
+                    ["Token moved", ZERO_ADDR],
+                    ["Moved to", OTHER_ADDR],
+                ]);
+            });
+        });
+
+        // https://git.eeqj.de/sneak/AutistMask/issues/682 — V4 pays a SETTLE
+        // of ETH from the router's own ETH, whichever payer the SETTLE names,
+        // and the router holds the transaction's value. On next at 36b2002 a
+        // SETTLE of 1 ETH that names the router as payer gave no ETH line.
+        describe("a V4 SETTLE of ETH that names the router as payer", () => {
+            const ONE_ETH = 1000000000000000000n;
+            // A V4 swap of `amount` of ETH for USDC. The SETTLE names the
+            // router as payer.
+            const v4EthFromRouter = (amount) =>
+                encodeV4Swap(
+                    new Uint8Array([
+                        V4_SWAP_EXACT_IN_SINGLE_ID,
+                        V4_SETTLE_ID,
+                        V4_TAKE_ALL_ID,
+                    ]),
+                    [
+                        encodeV4ExactInSingle(ZERO_ADDR, USDC_ADDR, amount, 1n),
+                        settle(ZERO_ADDR, amount, false),
+                        encodeV4TakeAll(USDC_ADDR, 1n),
+                    ],
+                );
+
+            test("after a V3 exact-in of 600 USDT, shows the 1 ETH moved from the sender", () => {
+                const result = decodeSteps(
+                    [0x00, 0x10],
+                    [V3_600, v4EthFromRouter(ONE_ETH)],
+                );
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "600.0000 USDT"],
+                    ["Moved from the sender", "1.0000 ETH"],
+                    ["Token moved", "ETH"],
+                    ["Moved to", "The swap step that spends it"],
+                ]);
+            });
+
+            // The UNWRAP_WETH leaves ETH in the router. The SETTLE may spend
+            // that ETH before the transaction's value.
+            test("after an UNWRAP_WETH into the router, shows at most 1 ETH moved from the sender", () => {
+                const result = decodeSteps(
+                    [0x00, 0x0c, 0x10],
+                    [
+                        encodeV3SwapExactIn(ROUTER_ADDR, USDT_600, 1n, [
+                            USDT_ADDR,
+                            WETH_ADDR,
+                        ]),
+                        encodeWrapEth(ROUTER_ADDR, 0n), // UNWRAP_WETH, same encoding
+                        v4EthFromRouter(ONE_ETH),
+                    ],
+                );
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "600.0000 USDT"],
+                    ["Moved from the sender", "Up to 1.0000 ETH"],
+                    ["Token moved", "ETH"],
+                    ["Moved to", "The swap step that spends it"],
+                ]);
+            });
+
+            test("after a WRAP_ETH of 0.5 ETH, adds the SETTLE's 0.5 ETH to the Amount line", () => {
+                const result = decodeSteps(
+                    [0x0b, 0x10],
+                    [
+                        encodeWrapEth(ROUTER_ADDR, ONE_ETH / 2n),
+                        v4EthFromRouter(ONE_ETH / 2n),
+                    ],
+                );
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "1.0000 ETH"],
+                ]);
+            });
+
+            // The WRAP_ETH sets Token In to ETH, and the UNWRAP_WETH leaves
+            // ETH in the router. The SETTLE may spend that ETH before the
+            // transaction's value, so its 1 ETH never joins the Amount line.
+            test("after a WRAP_ETH and an UNWRAP_WETH into the router, keeps the Amount line and shows at most 1 ETH moved from the sender", () => {
+                const result = decodeSteps(
+                    [0x0b, 0x0c, 0x10],
+                    [
+                        encodeWrapEth(ROUTER_ADDR, ONE_ETH / 2n),
+                        encodeWrapEth(ROUTER_ADDR, 0n), // UNWRAP_WETH, same encoding
+                        v4EthFromRouter(ONE_ETH),
+                    ],
+                );
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "0.5000 ETH"],
+                    ["Moved from the sender", "Up to 1.0000 ETH"],
+                    ["Token moved", "ETH"],
+                    ["Moved to", "The swap step that spends it"],
+                ]);
+            });
+
+            // A SETTLE of CONTRACT_BALANCE pays all the router holds, an
+            // amount the calldata does not state.
+            test("of CONTRACT_BALANCE, on the step that sets the input side, shows an unknown amount moved from the sender", () => {
+                const result = decodeSteps(
+                    [0x10],
+                    [
+                        encodeV4Swap(
+                            new Uint8Array([
+                                V4_SWAP_EXACT_IN_SINGLE_ID,
+                                V4_SETTLE_ID,
+                                V4_TAKE_ALL_ID,
+                            ]),
+                            [
+                                encodeV4ExactInSingle(
+                                    ZERO_ADDR,
+                                    USDC_ADDR,
+                                    ONE_ETH,
+                                    1n,
+                                ),
+                                settle(ZERO_ADDR, 2n ** 255n, false), // CONTRACT_BALANCE
+                                encodeV4TakeAll(USDC_ADDR, 1n),
+                            ],
+                        ),
+                    ],
+                );
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Moved from the sender", UNDECODED],
+                    ["Token moved", "ETH"],
+                    ["Moved to", "The swap step that spends it"],
+                ]);
+            });
+        });
+
+        // https://git.eeqj.de/sneak/AutistMask/issues/647 — on next at
+        // f550d8c, a split whose steps each pay WETH to the user showed only
+        // the last step's minimum.
+        describe("the minimum of a split that pays WETH to the user", () => {
+            const WETH_01 = 100000000000000000n;
+            const WETH_02 = 200000000000000000n;
+            const WETH_03 = 300000000000000000n;
+            // A V3 exact-in of 600 USDT for at least 0.3 WETH, and a V2
+            // exact-in of 400 USDT for at least 0.2 WETH, each paid to the
+            // user.
+            const V3_TO_WETH = encodeV3SwapExactIn(
+                USER_ADDR,
+                USDT_600,
+                WETH_03,
+                [USDT_ADDR, WETH_ADDR],
+            );
+            const V2_TO_WETH = encodeV2SwapExactIn(
+                USER_ADDR,
+                USDT_400,
+                WETH_02,
+                [USDT_ADDR, WETH_ADDR],
+            );
+            // A V4 step that swaps 400 USDT for at least 0.2 WETH, with these
+            // TAKEs of the WETH.
+            const v4ToWeth = (...takes) =>
+                encodeV4Swap(
+                    new Uint8Array([
+                        V4_SWAP_EXACT_IN_SINGLE_ID,
+                        V4_SETTLE_ID,
+                        ...takes.map(() => V4_TAKE_ID),
+                    ]),
+                    [
+                        encodeV4ExactInSingle(
+                            USDT_ADDR,
+                            WETH_ADDR,
+                            USDT_400,
+                            WETH_02,
+                        ),
+                        encodeV4Settle(USDT_ADDR), // paid by the user
+                        ...takes,
+                    ],
+                );
+            // The swap's minimum line as [label, value], or undefined.
+            const minimum = (result) =>
+                result.details
+                    .filter(
+                        (d) =>
+                            d.label === "Min. received" ||
+                            d.label === "Min. paid out",
+                    )
+                    .map((d) => [d.label, d.value])[0];
+
+            test("a V3 and a V2 exact-in show the total of their minimums", () => {
+                const result = decodeSteps(
+                    [0x00, 0x08],
+                    [V3_TO_WETH, V2_TO_WETH],
+                );
+                expect(minimum(result)).toEqual([
+                    "Min. received",
+                    "0.5000 WETH",
+                ]);
+            });
+
+            test("a V3 exact-in and a V4 step show the total of their minimums", () => {
+                const result = decodeSteps(
+                    [0x00, 0x10],
+                    [V3_TO_WETH, v4ToWeth(encodeV4Take(WETH_ADDR))],
+                );
+                expect(minimum(result)).toEqual([
+                    "Min. received",
+                    "0.5000 WETH",
+                ]);
+            });
+
+            // The second route buys DAI for the router, then swaps all of it
+            // from the router for at least 0.2 WETH.
+            test("a route that hops through DAI counts its last hop's minimum", () => {
+                const result = decodeSteps(
+                    [0x00, 0x08, 0x00],
+                    [
+                        V3_TO_WETH,
+                        encodeV2SwapExactIn(ROUTER_ADDR, USDT_400, DAI_400, [
+                            USDT_ADDR,
+                            DAI_ADDR,
+                        ]),
+                        coder.encode(
+                            ["address", "uint256", "uint256", "bytes", "bool"],
+                            [
+                                USER_ADDR,
+                                2n ** 255n, // CONTRACT_BALANCE
+                                WETH_02,
+                                encodeV3Path([DAI_ADDR, WETH_ADDR]),
+                                false, // paid from the router
+                            ],
+                        ),
+                    ],
+                );
+                expect(minimum(result)).toEqual([
+                    "Min. received",
+                    "0.5000 WETH",
+                ]);
+            });
+
+            // The middle step swaps 0.3 of the user's WETH for USDC, so the
+            // sum of minimums starts again after it.
+            test.each([
+                {
+                    kind: "a V3 exact-in",
+                    command: 0x00,
+                    input: encodeV3SwapExactIn(USER_ADDR, WETH_03, 1n, [
+                        WETH_ADDR,
+                        USDC_ADDR,
+                    ]),
+                },
+                {
+                    kind: "a V2 exact-in",
+                    command: 0x08,
+                    input: encodeV2SwapExactIn(USER_ADDR, WETH_03, 1n, [
+                        WETH_ADDR,
+                        USDC_ADDR,
+                    ]),
+                },
+                {
+                    kind: "a V2 exact-out",
+                    command: 0x09,
+                    input: encodeV2SwapExactOut(USER_ADDR, 1n, WETH_03, [
+                        WETH_ADDR,
+                        USDC_ADDR,
+                    ]),
+                },
+                {
+                    kind: "a V3 exact-out",
+                    command: 0x01,
+                    input: encodeV3SwapExactOut(USER_ADDR, 1n, WETH_03, [
+                        USDC_ADDR,
+                        WETH_ADDR,
+                    ]),
+                },
+            ])(
+                "$kind that spends WETH between them leaves the last step's minimum",
+                ({ command, input }) => {
+                    const result = decodeSteps(
+                        [0x00, command, 0x08],
+                        [V3_TO_WETH, input, V2_TO_WETH],
+                    );
+                    expect(minimum(result)).toEqual([
+                        "Min. received",
+                        "0.2000 WETH",
+                    ]);
+                },
+            );
+
+            // The middle step swaps 0.3 WETH and 400 DAI for USDC, both paid
+            // by the user. It spends WETH whichever SETTLE comes last.
+            test.each([
+                { order: "WETH first", settled: [WETH_ADDR, DAI_ADDR] },
+                { order: "DAI first", settled: [DAI_ADDR, WETH_ADDR] },
+            ])(
+                "a V4 step that spends WETH and DAI between them leaves the last step's minimum, with the SETTLE of $order",
+                ({ settled }) => {
+                    const wethAndDaiForUsdc = encodeV4Swap(
+                        new Uint8Array([
+                            V4_SWAP_EXACT_IN_SINGLE_ID,
+                            V4_SWAP_EXACT_IN_SINGLE_ID,
+                            V4_SETTLE_ID,
+                            V4_SETTLE_ID,
+                            V4_TAKE_ALL_ID,
+                        ]),
+                        [
+                            encodeV4ExactInSingle(
+                                WETH_ADDR,
+                                USDC_ADDR,
+                                WETH_03,
+                                1n,
+                            ),
+                            encodeV4ExactInSingle(
+                                DAI_ADDR,
+                                USDC_ADDR,
+                                DAI_400,
+                                1n,
+                            ),
+                            ...settled.map((token) => encodeV4Settle(token)),
+                            encodeV4TakeAll(USDC_ADDR, 0n),
+                        ],
+                    );
+                    const result = decodeSteps(
+                        [0x00, 0x10, 0x08],
+                        [V3_TO_WETH, wethAndDaiForUsdc, V2_TO_WETH],
+                    );
+                    expect(minimum(result)).toEqual([
+                        "Min. received",
+                        "0.2000 WETH",
+                    ]);
+                },
+            );
+
+            // The middle step's swap actions buy WETH with the user's USDT,
+            // then swap all of that WETH for USDC.
+            test("a V4 step that swaps through WETH between them leaves the last step's minimum", () => {
+                const usdtToUsdcThroughWeth = encodeV4Swap(
+                    new Uint8Array([
+                        V4_SWAP_EXACT_IN_SINGLE_ID,
+                        V4_SWAP_EXACT_IN_SINGLE_ID,
+                        V4_SETTLE_ID,
+                        V4_TAKE_ALL_ID,
+                    ]),
+                    [
+                        encodeV4ExactInSingle(
+                            USDT_ADDR,
+                            WETH_ADDR,
+                            USDT_400,
+                            WETH_01,
+                        ),
+                        encodeV4ExactInSingle(WETH_ADDR, USDC_ADDR, 0n, 1n),
+                        encodeV4Settle(USDT_ADDR), // paid by the user
+                        encodeV4TakeAll(USDC_ADDR, 0n),
+                    ],
+                );
+                const result = decodeSteps(
+                    [0x00, 0x10, 0x08],
+                    [V3_TO_WETH, usdtToUsdcThroughWeth, V2_TO_WETH],
+                );
+                expect(minimum(result)).toEqual([
+                    "Min. received",
+                    "0.2000 WETH",
+                ]);
+            });
+
+            // The middle step has no swap action. Its SETTLE or SETTLE_ALL
+            // pays 0.3 WETH, and its TAKE pays that WETH to another address.
+            test.each([
+                {
+                    payment: "a SETTLE of WETH paid by the user",
+                    actions: [V4_SETTLE_ID, V4_TAKE_ID],
+                    params: [
+                        settle(WETH_ADDR, WETH_03, true),
+                        take(WETH_ADDR, OTHER_ADDR, 0n),
+                    ],
+                },
+                {
+                    payment: "a SETTLE of WETH paid from the router",
+                    actions: [V4_SETTLE_ID, V4_TAKE_ID],
+                    params: [
+                        settle(WETH_ADDR, WETH_03, false),
+                        take(WETH_ADDR, OTHER_ADDR, 0n),
+                    ],
+                },
+                {
+                    payment: "a SETTLE_ALL of WETH",
+                    actions: [V4_TAKE_ID, V4_SETTLE_ALL_ID],
+                    params: [
+                        take(WETH_ADDR, OTHER_ADDR, WETH_03),
+                        encodeV4SettleAll(WETH_ADDR, WETH_03),
+                    ],
+                },
+            ])(
+                "a V4 step with $payment between them leaves the last step's minimum",
+                ({ actions, params }) => {
+                    const wethToOther = encodeV4Swap(
+                        new Uint8Array(actions),
+                        params,
+                    );
+                    const result = decodeSteps(
+                        [0x00, 0x10, 0x08],
+                        [V3_TO_WETH, wethToOther, V2_TO_WETH],
+                    );
+                    expect(minimum(result)).toEqual([
+                        "Min. paid out",
+                        "0.2000 WETH",
+                    ]);
+                },
+            );
+
+            test("a PERMIT2_TRANSFER_FROM of WETH between them leaves the last step's minimum", () => {
+                const result = decodeSteps(
+                    [0x00, 0x02, 0x08],
+                    [
+                        V3_TO_WETH,
+                        permit2TransferFrom(WETH_ADDR, OTHER_ADDR, WETH_03),
+                        V2_TO_WETH,
+                    ],
+                );
+                expect(minimum(result)).toEqual([
+                    "Min. paid out",
+                    "0.2000 WETH",
+                ]);
+            });
+
+            // The decoder reads no minimum from a V4 exact-out action.
+            test("a step that states no minimum leaves no figure", () => {
+                const exactOut = encodeV4Swap(
+                    new Uint8Array([
+                        V4_SWAP_EXACT_OUT_SINGLE_ID,
+                        V4_SETTLE_ALL_ID,
+                        V4_TAKE_ALL_ID,
+                    ]),
+                    [
+                        encodeV4ExactOutSingle(
+                            USDT_ADDR,
+                            WETH_ADDR,
+                            WETH_02,
+                            USDT_400,
+                        ),
+                        encodeV4SettleAll(USDT_ADDR, USDT_400),
+                        encodeV4TakeAll(WETH_ADDR, 0n),
+                    ],
+                );
+                const result = decodeSteps(
+                    [0x10, 0x00],
+                    [exactOut, V3_TO_WETH],
+                );
+                expect(minimum(result)).toBeUndefined();
+                expect(detail(result, "Paid to")).toBeUndefined();
+            });
+
+            test("a step that pays some of its WETH to the router leaves no figure", () => {
+                const result = decodeSteps(
+                    [0x00, 0x10],
+                    [
+                        V3_TO_WETH,
+                        v4ToWeth(
+                            take(WETH_ADDR, USER_ADDR, WETH_01),
+                            take(WETH_ADDR, ROUTER_ADDR, 0n),
+                        ),
+                    ],
+                );
+                expect(minimum(result)).toBeUndefined();
+            });
+
+            // The router still runs a swap step whose recipient cannot be
+            // read, and that step may spend the WETH the first step paid.
+            test("a step between them that cannot be read leaves no figure", () => {
+                const result = decodeSteps(
+                    [0x00, 0x00, 0x08],
+                    [
+                        V3_TO_WETH,
+                        dirtyWord(
+                            encodeV3SwapExactIn(USER_ADDR, WETH_03, 1n, [
+                                WETH_ADDR,
+                                USDC_ADDR,
+                            ]),
+                            0,
+                        ),
+                        V2_TO_WETH,
+                    ],
+                );
+                expect(minimum(result)).toBeUndefined();
+            });
+        });
     });
 
     // https://git.eeqj.de/sneak/AutistMask/issues/359 — the output half, in
@@ -4052,10 +4731,9 @@ describe("uniswap decoder", () => {
         expect(detail(result, "Min. received").value).toBe("2.0000 USDC");
     });
 
-    // With no minimum stated before it, a zero balance check is what sets the
-    // output side, and it guarantees nothing. No step pays anyone, so the
-    // minimum is not said to be received.
-    test("a zero balance check with no earlier minimum states no minimum", () => {
+    // A zero balance check sets neither Token Out nor the minimum. The route
+    // pays only the WRAP_ETH's WETH, to the router, where it stays.
+    test("a zero balance check after a WRAP_ETH into the router names no output token and no minimum", () => {
         const data = buildExecute(
             solidityPacked(["uint8", "uint8"], [0x0b, 0x0e]),
             [
@@ -4068,9 +4746,16 @@ describe("uniswap decoder", () => {
         const result = uniswap.decode(data, ROUTER_ADDR, "0x1", {}, USER_ADDR);
         expect(result).not.toBeNull();
 
-        expect(detail(result, "Token Out").value).toContain("USDT");
-        expect(detail(result, "Min. paid out").value).toBe(
-            "None (no minimum guaranteed)",
+        expect(detail(result, "Token Out").value).toBe(
+            "Unknown (not named in the calldata)",
+        );
+        expect(detail(result, "Min. paid out")).toBeUndefined();
+        expect(detail(result, "Min. received")).toBeUndefined();
+        expect(detail(result, "Paid to").value).toBe(
+            "The router, where it stays (no later step pays it out)",
+        );
+        expect(detail(result, "Token moved into the router").address).toBe(
+            WETH_ADDR,
         );
     });
 

tests/uniswapRecipient.test.js

@@ -688,6 +688,62 @@ describe("an UNWRAP_WETH makes the output ETH only when the router holds it", ()
         ]);
     });
 
+    // The same route, then a balance check of the sender's USDC with a zero
+    // minimum. The check guarantees nothing, so Token Out stays ETH
+    // (https://git.eeqj.de/sneak/AutistMask/issues/649).
+    test("the same route, then a zero balance check of USDC, still reads as ETH with no minimum", () => {
+        const result = decode(
+            execute(
+                v4Swap(
+                    SWAP_USDT_FOR_WETH,
+                    SETTLE_USDT,
+                    take(WETH, MSG_SENDER, (ONE_WETH * 6n) / 10n),
+                    take(WETH, ADDRESS_THIS),
+                ),
+                unwrapWeth(MSG_SENDER),
+                balanceCheck(USDC, 0n),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → ETH");
+        expect(detail(result, "Token Out").value).toBe("ETH");
+        expect(labels(result)).toEqual([
+            "Protocol",
+            "Token In",
+            "Amount",
+            "Token Out",
+            "Steps",
+            "Deadline",
+        ]);
+    });
+
+    // A PERMIT2_TRANSFER_FROM moves the sender's WETH into the router. An
+    // UNWRAP_WETH pays that WETH to the user as ETH. A zero balance check of
+    // USDC sets neither Token Out nor the minimum, before the UNWRAP_WETH or
+    // after it (https://git.eeqj.de/sneak/AutistMask/issues/649).
+    test.each([
+        {
+            kind: "before the UNWRAP_WETH",
+            steps: [balanceCheck(USDC, 0n), unwrapWeth(MSG_SENDER)],
+        },
+        {
+            kind: "after the UNWRAP_WETH",
+            steps: [unwrapWeth(MSG_SENDER), balanceCheck(USDC, 0n)],
+        },
+    ])(
+        "WETH moved into the router and unwrapped, with a zero balance check of USDC $kind, reads as ETH with no minimum",
+        ({ steps }) => {
+            const result = decode(
+                execute(
+                    permit2TransferFrom(WETH, ADDRESS_THIS, ONE_WETH),
+                    ...steps,
+                ),
+            );
+            expect(detail(result, "Token Out").value).toBe("ETH");
+            expect(detail(result, "Min. received")).toBeUndefined();
+            expect(detail(result, "Min. paid out")).toBeUndefined();
+        },
+    );
+
     // A TAKE the decoder cannot read may pay part of the WETH to the user.
     test("one V4 step paying WETH to the router beside a TAKE that cannot be read, then an UNWRAP_WETH, reads as ETH with no minimum", () => {
         const result = decode(
@@ -1661,9 +1717,18 @@ describe("any token left in the router is not received", () => {
             ),
             min: "1990.0000 USDC",
         },
-        {
-            kind: "a swap paying WETH to the router, an UNWRAP_WETH into the router, then a V4 swap settling all the ETH from the router",
-            data: execute(
+    ])("$kind reads as a swap paid to the user", ({ data, min }) => {
+        const result = decode(data);
+        expect(labels(result)).toEqual(PAID_TO_USER);
+        expect(detail(result, "Min. received").value).toBe(min);
+    });
+
+    // https://git.eeqj.de/sneak/AutistMask/issues/682 — the SETTLE spends all
+    // the router's ETH, the transaction's value included, so the sender pays
+    // an amount the calldata does not state.
+    test("a swap paying WETH to the router, an UNWRAP_WETH into the router, then a V4 swap settling all the ETH from the router reads as a swap paid to the user", () => {
+        const result = decode(
+            execute(
                 swapToWeth(ADDRESS_THIS),
                 unwrapWeth(ADDRESS_THIS),
                 v4Swap(
@@ -1672,12 +1737,23 @@ describe("any token left in the router is not received", () => {
                     takeAll(USDC),
                 ),
             ),
-            min: "1990.0000 USDC",
-        },
-    ])("$kind reads as a swap paid to the user", ({ data, min }) => {
-        const result = decode(data);
-        expect(labels(result)).toEqual(PAID_TO_USER);
-        expect(detail(result, "Min. received").value).toBe(min);
+        );
+        expect(labels(result)).toEqual([
+            "Protocol",
+            "Token In",
+            "Amount",
+            "Moved from the sender",
+            "Token moved",
+            "Moved to",
+            "Token Out",
+            "Min. received",
+            "Steps",
+            "Deadline",
+        ]);
+        expect(detail(result, "Moved from the sender").value).toBe(
+            "Unknown (could not be decoded)",
+        );
+        expect(detail(result, "Min. received").value).toBe("1990.0000 USDC");
     });
 });
 
@@ -2800,17 +2876,16 @@ describe("the allow-revert flag", () => {
         },
     );
 
-    test("a BALANCE_CHECK_ERC20 with the flag, and no minimum before it, states none", () => {
+    test("a BALANCE_CHECK_ERC20 with the flag, and no minimum before it, names no output token and no minimum", () => {
         const check = balanceCheck(WETH, ONE_WETH);
         expect(detail(decode(execute(check)), "Min. paid out").value).toBe(
             "1.0000 WETH",
         );
 
         const withFlag = decode(execute(flagged(check)));
-        expect(detail(withFlag, "Token Out").address).toBe(WETH);
-        expect(detail(withFlag, "Min. paid out").value).toBe(
-            "None (no minimum guaranteed)",
-        );
+        expect(detail(withFlag, "Token Out").value).toBe(UNNAMED);
+        expect(detail(withFlag, "Min. paid out")).toBeUndefined();
+        expect(detail(withFlag, "Min. received")).toBeUndefined();
     });
 
     // Only the routers from UniversalRouterV2 on let a PERMIT2_PERMIT fail.

tests/walletDefects.test.js

@@ -357,6 +357,11 @@ describe("every way to a signature or the private key refuses a defective wallet
     });
 
     beforeEach(() => {
+        // showFlash() starts a timer that clears the message two seconds
+        // later. Each test here runs on fake timers and drops them in
+        // afterEach, so that timer never outlives the test.
+        jest.useFakeTimers();
+
         const broken = brokenXprvWallet();
         // A balance, so that no Send button's zero-balance refusal can stand
         // in for the defect check.
@@ -398,6 +403,7 @@ describe("every way to a signature or the private key refuses a defective wallet
     });
 
     afterEach(() => {
+        jest.useRealTimers();
         state.wallets = [];
         state.activeAddress = null;
         state.selectedWallet = null;