fix: a refresh asked for while another runs is no longer dropped (closes #581)

doRefreshAndRender() returned at once when a refresh was already running. An import asks for a refresh after its address scan, and that request was dropped when it came during a refresh, so the addresses the scan found showed 0.0000 until the next ten-second refresh. A request made through ctx while a refresh runs now leads to one more refresh once the running one ends, however many such requests came in. A tick of the ten-second timer during a refresh is still dropped, so the wallet asks the node no more often than before.

Model: opus-5-5

README.md

@@ -1277,22 +1277,18 @@ 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
+- `None (no minimum guaranteed)`: the swap's `Min. received` line, when it shows
-  minimum it shows is zero, whether a V2, V3 or V4 swap's minimum or a
+  a V2, V3 or V4 swap's minimum of zero. The router passes a
-  `BALANCE_CHECK_ERC20` step's `minBalance`. Before
+  `BALANCE_CHECK_ERC20` step whenever the balance is at least `minBalance`, so a
-  [#359](https://git.eeqj.de/sneak/AutistMask/issues/359), a zero `minBalance`
+  zero `minBalance` guarantees nothing. A check with a zero `minBalance` sets
-  read `0.0000` when the token's scale was known. The router passes a balance
+  neither `Token Out` nor `Min. received`. A nonzero `minBalance` sets both
-  check whenever the balance is at least `minBalance`, so a zero `minBalance`
+  lines, as a swap step does. Only a check of the transaction's sender's own
-  guarantees nothing: it sets `Token Out` and `Min. received` only when the
+  balance sets either line; a check of any other address sets neither (see
-  output side holds no minimum, not even a zero one, at the point the check is
+  Transaction Decoding). A `BALANCE_CHECK_ERC20` step that the router lets fail
-  reached, and otherwise leaves the current token and figure in place. A nonzero
+  without reverting the transaction (see Transaction Decoding) guarantees
-  `minBalance` sets both lines, as a swap step does. Only a check of the
+  nothing either, whatever its `minBalance`, and is read as one whose
-  transaction's sender's own balance sets either line; a check of any other
+  `minBalance` is zero. A minimum stated by a V4 swap step the router lets fail
-  address sets neither (see Transaction Decoding). A `BALANCE_CHECK_ERC20` step
+  is likewise read as zero.
-  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
@@ -2281,6 +2277,11 @@ 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
     - Etherscan:
         - "Check recipients on Etherscan" checkbox, unticked until the user
           ticks it
@@ -3395,7 +3396,8 @@ 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
@@ -3477,119 +3479,133 @@ Currently supported:
   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
+  rest taken to another address, reads `5000.0000 USDT`. A later step that pays
-  the router spends what the router holds and takes nothing, and so does a V2
+  an ERC-20 token from the router takes none of that token from the user's
-  exact-in whose `amountIn` is `ALREADY_PAID`. A later take of `Token In` is
+  wallet. A V2 exact-in whose `amountIn` is `ALREADY_PAID` takes nothing either.
-  added to the total while both are quantities: a V3 exact-in of 600 USDT and a
+  A V4 `SETTLE` of ETH paid from the router still takes from the user's wallet,
-  V2 exact-in of 400 USDT, both paid by the user, read `1000.0000 USDT`. When
+  since the router holds the transaction's value. When the decoder does not know
-  the decoder does not know a take's amount, the total is not known and there is
+  the amount of such a `SETTLE`, as for `CONTRACT_BALANCE`, that `SETTLE` counts
-  no `Amount` line. A `PERMIT2_PERMIT` names `Token In` only when its amount,
+  as a later step's take. When an earlier step left ETH in the router, that ETH
-  `Unlimited` included, stands as the `Amount` figure in place of the total,
+  may pay part of a `SETTLE` of ETH paid from the router. That `SETTLE` then
-  which it does only in the plain shape of Uniswap's own routes: it comes before
+  gets lines of its own, with `Up to` before its amount. A later take of
-  the step that sets the input side, it is the only `PERMIT2_PERMIT` in the
+  `Token In` that only the user's wallet pays is added to the total while both
-  transaction and there is no `PERMIT2_PERMIT_BATCH`, its spender is the router,
+  are quantities: a V3 exact-in of 600 USDT and a V2 exact-in of 400 USDT, both
-  the router may not let it fail, no step before it takes its token, a
+  paid by the user, read `1000.0000 USDT`. When the decoder does not know a
-  `PERMIT2_TRANSFER_FROM` of it included, or a token the decoder does not know,
+  take's amount, the total is not known and there is no `Amount` line. A
-  and the decoder reads every step after it in full. Permit2 then lets the
+  `PERMIT2_PERMIT` names `Token In` only when its amount, `Unlimited` included,
-  router take no more of the token than that amount, so the permit covers every
+  stands as the `Amount` figure in place of the total, which it does only in the
-  take of it. A step before the permit takes under whatever allowance the router
+  plain shape of Uniswap's own routes: it comes before the step that sets the
-  already had, so it may take more than the permit's amount, which would then
+  input side, it is the only `PERMIT2_PERMIT` in the transaction and there is no
-  read lower than what leaves the user's wallet: a `PERMIT2_TRANSFER_FROM` of
+  `PERMIT2_PERMIT_BATCH`, its spender is the router, the router may not let it
-  2,000 USDT into the router, then a permit of 600 USDT to the router and a V3
+  fail, no step before it takes its token, a `PERMIT2_TRANSFER_FROM` of it
-  exact-in of 2,000 USDT paid from the router, read `Amount 2000.0000 USDT`. A
+  included, or a token the decoder does not know, and the decoder reads every
-  later permit or batch may raise what Permit2 lets the router take, and so may
+  step after it in full. Permit2 then lets the router take no more of the token
-  a step the decoder does not read in full: a command the decoder does not read
+  than that amount, so the permit covers every take of it. A step before the
-  (listed at the end of this section), a step whose input it cannot read, in
+  permit takes under whatever allowance the router already had, so it may take
-  whole or in part, and a step it fails on. Every other `PERMIT2_PERMIT`, before
+  more than the permit's amount, which would then read lower than what leaves
-  the step that sets the input side or after it, leaves `Token In` and the
+  the user's wallet: a `PERMIT2_TRANSFER_FROM` of 2,000 USDT into the router,
-  `Amount` line as they read with no permit, unless it lets a spender other than
+  then a permit of 600 USDT to the router and a V3 exact-in of 2,000 USDT paid
-  the router take `Token In` (see below): a permit of 5,000 DAI to another
+  from the router, read `Amount 2000.0000 USDT`. A later permit or batch may
-  address and then a V3 exact-in of 600 USDT read `Swap USDT → USDC` with
+  raise what Permit2 lets the router take, and so may a step the decoder does
-  `Amount 600.0000 USDT`, and so do that exact-in and then a permit of 5,000 DAI
+  not read in full: a command the decoder does not read (listed at the end of
-  to the router. When a permit's amount stands and the step that sets the input
+  this section), a step whose input it cannot read, in whole or in part, and a
-  side spends a token other than the permit's, or one the decoder does not know,
+  step it fails on. Every other `PERMIT2_PERMIT`, before the step that sets the
-  that step's amount gets lines of its own, unless it states no amount and the
+  input side or after it, leaves `Token In` and the `Amount` line as they read
-  user pays it none of its input token. Each take the total does not count gives
+  with no permit, unless it lets a spender other than the router take `Token In`
-  three lines after the `Amount` line (after `Token In` when there is none): one
+  (see below): a permit of 5,000 DAI to another address and then a V3 exact-in
-  of a token other than `Token In`; one of `Token In` after an amount that is
+  of 600 USDT read `Swap USDT → USDC` with `Amount 600.0000 USDT`, and so do
-  not a quantity (a V4 open delta, `ALREADY_PAID`, which keep their wording on
+  that exact-in and then a permit of 5,000 DAI to the router. A permit on the
-  the `Amount` line, or no stated amount, as of a V4 exact-out step); and one
+  zero address never stands as the `Amount` figure, because Permit2 has no
-  whose amount the decoder does not know. When there is no `Amount` line, each
+  allowance of ETH. When a permit's amount stands and the step that sets the
-  take the total counts gets them too, so that every amount the decoder reads is
+  input side spends a token other than the permit's, or one the decoder does not
-  shown: the amount the step that sets the input side states, when it is a
+  know, that step's amount gets lines of its own, unless it states no amount and
-  quantity and the user pays that step (a V2 or V3 step whose `payerIsUser` is
+  the user pays it none of its input token. Each take the total does not count
-  true, a V4 step the user pays some of its input token, or a `WRAP_ETH`, whose
+  gives three lines after the `Amount` line (after `Token In` when there is
-  ETH comes from the transaction's value), and each later take of `Token In`
+  none): one of a token other than `Token In`; one of `Token In` after an amount
-  added to it. A step that sets the input side and is paid from the router takes
+  that is not a quantity (a V4 open delta, `ALREADY_PAID`, which keep their
-  nothing from the user's wallet and gets none. A `PERMIT2_PERMIT` the decoder
+  wording on the `Amount` line, or no stated amount, as of a V4 exact-out step);
-  cannot read, then V3 exact-ins of 600 USDT and 400 DAI paid by the user, give
+  an ETH take whose line reads `Up to` (see above); and one whose amount the
-  lines for both amounts. When the step that sets the input side states no
+  decoder does not know. When there is no `Amount` line, each take the total
-  amount, the user pays it some of its input token, and there is no `Amount`
+  counts gets them too, so that every amount the decoder reads is shown: the
-  line, that step gets them too whenever another take's lines give a figure, or
+  amount the step that sets the input side states, when it is a quantity and the
-  a `PERMIT2_TRANSFER_FROM` of its token gives one, on the lines below or, into
+  user pays that step (a V2 or V3 step whose `payerIsUser` is true, a V4 step
-  the router, on its `Paid to` line, so that figure cannot read as all that
+  the user pays some of its input token, or a `WRAP_ETH`, whose ETH comes from
-  leaves. When it states no amount and the user pays it none of its input token,
+  the transaction's value), and each later take of `Token In` added to it. A
-  as when the router pays it, that step takes none of that token from the user's
+  step that sets the input side gets none when the user pays it none of its
-  wallet and never gets them, with a permit or without. They come in step order,
+  input token. A `PERMIT2_PERMIT` the decoder cannot read, then V3 exact-ins of
-  except that the step that sets the input side comes first when it has them,
+  600 USDT and 400 DAI paid by the user, give lines for both amounts. When the
-  followed, when there is no `Amount` line, by the other takes the total counts:
+  step that sets the input side states no amount, the user pays it some of its
-  `Moved from the sender`, its amount, worded as the `Amount` line words one, or
+  input token, and there is no `Amount` line, that step gets them too whenever
-  `Unknown (could not be decoded)` when the decoder does not know it;
+  another take's lines give a figure, or a `PERMIT2_TRANSFER_FROM` of its token
-  `Token moved`, giving the token's address as the `Token In` line does; and
+  gives one, on the lines below or, into the router, on its `Paid to` line, so
-  `Moved to`, which reads `The swap step that spends it`. A token the decoder
+  that figure cannot read as all that leaves. When it states no amount and the
-  does not know gives the `Moved from the sender` line alone. A step may also
+  user pays it none of its input token, that step never gets them, with a permit
-  take from the user's wallet what the decoder did not read: a V4 step whose
+  or without. They come in step order, except that the step that sets the input
-  input or one of whose `SETTLE`s or `SETTLE_ALL`s it cannot read, which the
+  side comes first when it has them, followed, when there is no `Amount` line,
-  router still runs; a V2 or V3 exact-in or exact-out step or a
+  by the other takes the total counts: `Moved from the sender`, its amount,
-  `PERMIT2_TRANSFER_FROM` whose input it cannot read, such as a V3 step whose
+  worded as the `Amount` line words one, or `Unknown (could not be decoded)`
-  path is shorter than one token address or has bytes after its last hop; every
+  when the decoder does not know it; `Token moved`, giving the token's address
-  `PERMIT2_TRANSFER_FROM_BATCH`; every `EXECUTE_SUB_PLAN`, wherever it stands;
+  as the `Token In` line does; and `Moved to`, which reads
-  and every step it fails on. Each such step gives one `Moved from the sender`
+  `The swap step that spends it`. A token the decoder does not know gives the
-  line among those, reading `Unknown (could not be decoded)`. That line, or any
+  `Moved from the sender` line alone. A step may also take from the user's
-  line for a token the decoder does not know, leaves no `Amount` line, whose
+  wallet what the decoder did not read: a V4 step whose input or one of whose
-  figure might be too low, and such a step before a `PERMIT2_PERMIT` keeps the
+  `SETTLE`s or `SETTLE_ALL`s it cannot read, which the router still runs; a V2
-  permit's amount from standing. Then each `PERMIT2_TRANSFER_FROM` but one into
+  or V3 exact-in or exact-out step or a `PERMIT2_TRANSFER_FROM` whose input it
-  the router, in step order, gives three lines: `Moved from the sender`, the
+  cannot read, such as a V3 step whose path is shorter than one token address or
-  amount it moves, for example `1000000.0000 USDT`; `Token moved`, giving the
+  has bytes after its last hop; every `PERMIT2_TRANSFER_FROM_BATCH`; every
-  token's address as the `Token In` line does; and `Moved to`, which reads
+  `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
+  where it goes, and so its amount is shown once. For a move of the zero
-  amount does not stand as the `Amount` figure, before the step that sets the
+  address, `Moved from the sender` gives the amount in base units and
-  input side or after it, gives three lines, in step order, after those for each
+  `Token moved` gives the zero address. For such a move into the router, the
-  `PERMIT2_TRANSFER_FROM`: `Permit2 allowance`, its amount, for example
+  `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
+  three lines, in step order with those of each `PERMIT2_PERMIT`. For an
-  `PERMIT2_PERMIT` or `PERMIT2_PERMIT_BATCH` whose input the decoder cannot
+  allowance of the zero address, `Permit2 allowance` gives the amount in base
-  read, such as one whose token or spender word has a nonzero top byte, may let
+  units and `Allowance token` gives the zero address. A `PERMIT2_PERMIT` or
-  any spender take any amount of any token: it gives one `Permit2 allowance`
+  `PERMIT2_PERMIT_BATCH` whose input the decoder cannot read, such as one whose
-  line alone, reading `Unknown (could not be decoded)`. These lines change no
+  token or spender word has a nonzero top byte, may let any spender take any
-  `Paid to` line: a permit or batch pays nobody. But code that a step runs, such
+  amount of any token: it gives one `Permit2 allowance` line alone, reading
-  as a V4 pool's hook or a token's own code, can call a spender other than the
+  `Unknown (could not be decoded)`. These lines change no `Paid to` line: a
-  router, which can then take up to its allowance from the user's wallet before
+  permit or batch pays nobody. But code that a step runs, such as a V4 pool's
-  the transaction ends. So an allowance to any spender but the router, or a
+  hook or a token's own code, can call a spender other than the router, which
-  permit or batch the decoder cannot read, makes the minimum read
+  can then take up to its allowance from the user's wallet before the
-  `Min. paid out`, and when its token is `Token In`, or the decoder does not
+  transaction ends. So an allowance to any spender but the router, or a permit
-  know its token or `Token In`, it leaves no `Amount` line, whose figure might
+  or batch the decoder cannot read, makes the minimum read `Min. paid out`, and
-  be too low: a permit of 5,000 USDT to another address and then a V3 exact-in
+  when its token is `Token In`, or the decoder does not know its token or
-  of 600 USDT read with no `Amount` line, and the 600 USDT gets lines of its
+  `Token In`, it leaves no `Amount` line, whose figure might be too low: a
-  own. A step goes unread when its recipient does not decode as an address, when
+  permit of 5,000 USDT to another address and then a V3 exact-in of 600 USDT
-  it is a V3 swap step whose path is shorter than one token address or has bytes
+  read with no `Amount` line, and the 600 USDT gets lines of its own. A step
-  after its last hop, or when it is a command the decoder does not read: every
+  goes unread when its recipient does not decode as an address, when it is a V3
-  command other than `PERMIT2_PERMIT`, `PERMIT2_PERMIT_BATCH`,
+  swap step whose path is shorter than one token address or has bytes after its
-  `PERMIT2_TRANSFER_FROM`, `V2_SWAP_EXACT_IN`, `V2_SWAP_EXACT_OUT`,
+  last hop, or when it is a command the decoder does not read: every command
-  `V3_SWAP_EXACT_IN`, `V3_SWAP_EXACT_OUT`, `V4_SWAP`, `SWEEP`, `TRANSFER`,
+  other than `PERMIT2_PERMIT`, `PERMIT2_PERMIT_BATCH`, `PERMIT2_TRANSFER_FROM`,
-  `PAY_PORTION`, `PAY_PORTION_FULL_PRECISION`, `ACROSS_V4_DEPOSIT_V3`,
+  `V2_SWAP_EXACT_IN`, `V2_SWAP_EXACT_OUT`, `V3_SWAP_EXACT_IN`,
-  `WRAP_ETH`, `UNWRAP_WETH` and `BALANCE_CHECK_ERC20`
+  `V3_SWAP_EXACT_OUT`, `V4_SWAP`, `SWEEP`, `TRANSFER`, `PAY_PORTION`,
-  (`PERMIT2_TRANSFER_FROM_BATCH`, `EXECUTE_SUB_PLAN` and the NFT commands among
+  `PAY_PORTION_FULL_PRECISION`, `ACROSS_V4_DEPOSIT_V3`, `WRAP_ETH`,
-  them), or a type its release names no command for.
+  `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
 

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
+        // No caller waits for this function, so it must never reject. An
-        // second interval, and eight views through ctx — so it must never
+        // unhandled rejection reports nothing. The save inside it reports its
-        // reject: an unhandled rejection is not a report of anything. The save
+        // own failure through onSaveFailure() (see src/shared/state.js); what
-        // inside it reports its own failure through onSaveFailure() (see
+        // is left here is a failed network round trip, which the next tick
-        // src/shared/state.js); what is left here is a failed network round
+        // retries.
-        // 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
+// (https://git.eeqj.de/sneak/AutistMask/issues/530). With the ten-second
-// running it starts no second one, and on the recovery screen it does nothing.
+// 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/settings.js

@@ -44,6 +44,12 @@ 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;
+
 // 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 +205,7 @@ function renderWalletListSettings() {
 }
 
 function show() {
+    shownNetwork = currentNetwork();
     $("settings-rpc").value = state.rpcUrl;
     $("settings-blockscout").value = state.blockscoutUrl;
     $("settings-network").value = state.networkId;
@@ -306,6 +313,7 @@ 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;
@@ -319,6 +327,48 @@ 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`.
+async function saveEndpoint(field, input, url, networkId) {
+    let refused = false;
+    let inputChanged = false;
+    await saveState((stored) => {
+        refused =
+            state.networkId !== networkId || stored.networkId !== networkId;
+        inputChanged = $(input).value.trim() !== url;
+        if (refused || inputChanged) return false;
+        state[field] = url;
+        stored[field] = url;
+    });
+    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);
@@ -330,6 +380,8 @@ function init(_ctx) {
             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, {
@@ -348,7 +400,6 @@ function init(_ctx) {
                 showFlash("Endpoint returned an error.");
                 return;
             }
-            const net = currentNetwork();
             if (json.result !== net.chainId) {
                 showFlash("Wrong network: expected " + net.name + ".");
                 return;
@@ -364,9 +415,7 @@ function init(_ctx) {
             showFlash("Could not reach endpoint.");
             return;
         }
-        state.rpcUrl = url;
+        await saveEndpoint("rpcUrl", "settings-rpc", url, net.id);
-        await saveState();
-        showFlash("Saved.");
     });
 
     $("btn-save-blockscout").addEventListener("click", async () => {
@@ -375,6 +424,7 @@ function init(_ctx) {
             showFlash("Please enter a Blockscout API URL.");
             return;
         }
+        const net = shownNetwork;
         showFlash("Testing endpoint...");
         try {
             const resp = await debugFetch(url + "/stats");
@@ -389,9 +439,7 @@ function init(_ctx) {
             showFlash("Could not reach endpoint.");
             return;
         }
-        state.blockscoutUrl = url;
+        await saveEndpoint("blockscoutUrl", "settings-blockscout", url, net.id);
-        await saveState();
-        showFlash("Saved.");
     });
 
     // Each change is made inside the save, holding the lock. So

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 +47,43 @@ 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).
+//
+// 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. When the stored record is on another network, a switch saved
+// elsewhere has not reached this page yet. The stored record's tokens are then
+// that network's, and none are taken.
 async function onChainSwitch(newNetworkId) {
-    const { state, saveState } = require("./state");
+    const { state, saveState, takeStoredTrackedTokens } = require("./state");
     let net = null;
-    await saveState(() => {
+    await saveState((stored) => {
         if (state.networkId === newNetworkId) return false;
+        if (stored.networkId === state.networkId) {
+            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()
+// `baseline` holds the persisted fields as this page held them when its last
-// finished, or when its last successful saveState() began, with any network
+// loadState() finished, or when its last successful saveState() began.
-// switch saved elsewhere that this page has taken since (takeStoredNetwork()).
+// takeStoredNetwork() and takeStoredTrackedTokens() also write into it what
-// saveState() diffs the live state against this to find only the fields THIS
+// this page has taken from the stored record since then. saveState() diffs the
-// page changed since.
+// 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
@@ -442,8 +443,10 @@ 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
+// `fraudContracts`/`viewStack` are arrays of scalars with no per-element
-// per-element identity to merge by; `networkTrackedTokens` is diffed whole like
+// 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
@@ -591,8 +594,10 @@ 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
+// `state`, and this save writes that change. It may also change the stored
-// written; any other return lets the save go ahead.
+// 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
@@ -613,6 +618,28 @@ function takeStoredNetwork(stored) {
     copyChainSwitchFields(baseline, structuredClone(stored));
 }
 
+// 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);
+}
+
 // Rejects with StateUnusableError for a stored record this build cannot make
 // sense of. Nothing is assigned and `loaded` stays false in that case, so a
 // caller that ignores the rejection gets StateNotLoadedError on the first
@@ -659,6 +686,7 @@ module.exports = {
     saveState,
     onSaveFailure,
     takeStoredNetwork,
+    takeStoredTrackedTokens,
     loadState,
     currentAddress,
     currentNetwork,

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.
+// one. `info` is what tokenInfo() or permit2TokenInfo() gives for the token.
-function tokenMovedLine(label, token, sources) {
+// ETH has no address.
-    const info = tokenInfo(token, sources);
+function tokenMovedLine(label, info) {
     if (!present(info.address)) {
         return { label, value: info.symbol };
     }
     return {
         label,
-        value: info.symbol ? info.symbol + " (" + token + ")" : token,
+        value: info.symbol
-        address: token,
+            ? info.symbol + " (" + info.address + ")"
+            : info.address,
+        address: info.address,
         isToken: true,
     };
 }
@@ -1240,9 +1253,10 @@ 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
+        // its input currency (see paidByUser in the loop), or a WRAP_ETH,
-        // comes from the transaction's value. A step paid from the router
+        // whose ETH comes from the transaction's value. A step that pays an
-        // takes nothing from the sender.
+        // 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).
@@ -1338,7 +1352,9 @@ 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
@@ -1613,13 +1629,13 @@ 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
+                        // nothing. A check the router lets fail guarantees
-                        // step stated. A check the router lets fail guarantees
+                        // nothing either, so it is read as a zero one. A zero
-                        // nothing either, so it is read as a zero one. Any
+                        // 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;
@@ -1815,6 +1831,41 @@ 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.
@@ -1845,10 +1896,10 @@ 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
+                    // user pays it of its input currency, or, when the user
-                    // decodeV4Swap()), or, when the user pays none of it,
+                    // pays none of it, what its swap actions spend of it,
-                    // what its swap actions spend of it, whoever pays that.
+                    // whoever pays that.
-                    const paidIn = v4?.paidByUser.find(
+                    const paidIn = paidByUser.find(
                         (p) => p.currency === v4.tokenIn,
                     );
                     const amountIn = paidIn ? paidIn.amount : v4?.amountIn;
@@ -1902,10 +1953,24 @@ 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 paidByUser) {
-                        for (const p of v4.paidByUser) {
+                        if (setInputHere && p === paidIn) continue;
-                            if (setInputHere && p === paidIn) continue;
+                        addUserPaid(p.currency, p.amount);
-                            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 +2078,10 @@ 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
+        // being of another token, coming after an amount that is not a
-        // quantity (a V4 open delta, ALREADY_PAID, or none stated), gets
+        // quantity (a V4 open delta, ALREADY_PAID, or none stated), or having
-        // lines of its own. One whose amount is not known also leaves the
+        // `atMost` set, gets lines of its own. One whose amount is not known
-        // total unknown, with no figure.
+        // 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 +2097,14 @@ 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
+        // they read with no permit, and gets lines of its own below. A permit
-        // that may take from the sender what this decoder did not read leaves
+        // on the zero address never stands as the Amount figure, because
-        // no figure, permit or not (see spentUnread()), and so do a permit
+        // Permit2 has no allowance of ETH. A step that may take from the
-        // or batch whose input it cannot read (see permitUnread()) and an
+        // sender what this decoder did not read leaves no figure, permit or
-        // allowance of Token In to another spender (see toAnotherSpender). An
+        // not (see spentUnread()), and so do a permit or batch whose input it
-        // EXECUTE_SUB_PLAN step leaves both sides unknown (below).
+        // 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 +2114,7 @@ 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 +2125,14 @@ 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
+        // its own (see below). The amount of the step that set the input side
-        // and is paid from the router counts in `total` but is not among them.
+        // 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
+        // some of its input token.
-        // from the sender.
         const hasFirstTake =
             inputEstablished && (present(inputAmount) || inputPaidByUser);
         // The take of the step that set the input side, when the total
@@ -2090,7 +2158,8 @@ 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 +2262,9 @@ 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.
+        // compared with one. `atMost` marks an amount that is only the most a
-        const spentText = (amount, info) => {
+        // 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 +2277,7 @@ 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 +2304,19 @@ 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
+        // too low. An allowance of the zero address is never one of Token In,
-        // lines of its own, first, so that every amount this decoder read is
+        // because Permit2 has no allowance of ETH. With no Amount line, each
-        // shown.
+        // 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) &&
+                    p.token === "0x0000000000000000000000000000000000000000" ||
-                    present(inputToken) &&
+                    (present(p.token) &&
-                    !sameAddress(p.token, inputToken),
+                        present(inputToken) &&
+                        !sameAddress(p.token, inputToken)),
             )
         ) {
             const amount = spentText(inputAmount, inInfo);
@@ -2265,11 +2337,14 @@ 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 +2355,12 @@ 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))
+                value: amountText(m.amount, info).display,
-                    .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 +2390,15 @@ 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))
+                        : amountText(p.amount, info).display,
-                              .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 +2456,7 @@ 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 +2464,7 @@ 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(
+            paidTo.push(tokenMovedLine("Token moved into the router", info));
-                tokenMovedLine("Token moved into the router", m.token, sources),
-            );
         }
         if (outputHeld) {
             paidTo.push({ label: "Paid to", value: STAYS_IN_ROUTER });
@@ -2408,8 +2481,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             paidTo.push(
                 tokenMovedLine(
                     "Token moved into the router",
-                    getAddress(token),
+                    tokenInfo(getAddress(token), sources),
-                    sources,
                 ),
             );
         }

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/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/settingsEndpointSave.test.js

@@ -0,0 +1,169 @@
+// 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.",
+        );
+    },
+);

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 +180,164 @@ 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 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",
+        },
+    ]);
+});
+
 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

@@ -3310,6 +3310,334 @@ 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/359 — the output half, in
@@ -4052,10 +4380,9 @@ 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
+    // A zero balance check sets neither Token Out nor the minimum. The route
-    // output side, and it guarantees nothing. No step pays anyone, so the
+    // pays only the WRAP_ETH's WETH, to the router, where it stays.
-    // minimum is not said to be received.
+    test("a zero balance check after a WRAP_ETH into the router names no output token and no minimum", () => {
-    test("a zero balance check with no earlier minimum states no minimum", () => {
         const data = buildExecute(
             solidityPacked(["uint8", "uint8"], [0x0b, 0x0e]),
             [
@@ -4068,9 +4395,16 @@ 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, "Token Out").value).toBe(
-        expect(detail(result, "Min. paid out").value).toBe(
+            "Unknown (not named in the calldata)",
-            "None (no minimum guaranteed)",
+        );
+        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 reads as a swap paid to the user", ({ data, min }) => {
-            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",
+        const result = decode(data);
-            data: execute(
+        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",
+        );
-        },
+        expect(labels(result)).toEqual([
-    ])("$kind reads as a swap paid to the user", ({ data, min }) => {
+            "Protocol",
-        const result = decode(data);
+            "Token In",
-        expect(labels(result)).toEqual(PAID_TO_USER);
+            "Amount",
-        expect(detail(result, "Min. received").value).toBe(min);
+            "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, "Token Out").value).toBe(UNNAMED);
-        expect(detail(withFlag, "Min. paid out").value).toBe(
+        expect(detail(withFlag, "Min. paid out")).toBeUndefined();
-            "None (no minimum guaranteed)",
+        expect(detail(withFlag, "Min. received")).toBeUndefined();
-        );
     });
 
     // Only the routers from UniversalRouterV2 on let a PERMIT2_PERMIT fail.