fix: only a permit whose amount is the Amount figure names Token In (closes #370)

A PERMIT2_PERMIT named Token In whether or not its amount stood as the
Amount figure, so the approval screen could show a permit's token, or an
allowance, where the swap's own input belonged.

Now only a permit whose amount stands names Token In. Every other
permit, before the swap steps or after them, leaves Token In and Amount
as they read with no permit and gets three lines of its own: Permit2
allowance, Allowance token and Allowance spender. A V3 swap step's
tokens are checksummed, as every other decoded address is, so a token's
address reads the same on every line. README Transaction Decoding, its
unknown token scale passage and the TxApproval element list match.

Model: opus-5-5

README.md

@@ -500,9 +500,12 @@ papered over:
   forced by clicking Reveal and the settings gear in one page task, which a
   person cannot do; the case a person can hit, the first decrypt after the popup
   opens while libsodium is still loading, is not driven.
-- Approval windows open at 1280x720 whatever size the extension asks for, so
-  whether an approval screen fits its window is checked in the Firefox suite
-  only.
+- Approval windows open at 1280x720 whatever size the extension asks for. The
+  site-connection prompt and the transaction approval are checked for sideways
+  scrolling at 396x600 by sizing the page itself for that measurement only, and
+  the rest of each test runs at 1280x720. That leaves out the window's frame and
+  the page widening its window, so whether an approval screen fits its window is
+  checked in the Firefox suite only.
 
 Any test that drives a failure path on purpose declares the `console.error` it
 is about to provoke, via `errors.expect()`. That is not a mute: the declaration
@@ -1116,22 +1119,25 @@ with the same floor (`.5` reads `.5000`).
 
 **Specific Exception — unknown token scale:** Calldata carries base units and no
 scale, so every amount on the dApp approval screen needs the token's `decimals`.
-It is resolved from the bundled token list, then from the tokens the user
-tracks, then from what the block explorer reported for the contract
-(`resolveTokenDecimals()` in `src/shared/approvalAmount.js`). Where none of them
-answers, the amount is not formatted: the line reads
-`5000000000 base units (decimals unknown)`. A guessed scale is not an
-approximation but a different number — 1,000 units of a 6-decimal token
-formatted at 18 decimals reads `0.000000001` — on the screen whose only job is
-to state what is being authorized. Both amount paths of that screen take this
-rule: the ERC-20 `transfer`/`approve` line (`src/popup/views/approval.js`) and
-the swap's `Amount` and `Min. received` lines (`src/shared/uniswap.js`). The
-token permission warning on the signature screen takes the same rule for its
-amounts. An unbounded allowance or permit needs no scale to describe and is
-still shown as `Unlimited`. A source's answer counts only if it is a whole
-number from 0 to 80: `decimals()` returns a `uint8`, but `formatUnits()` cannot
-format more than 80 decimal places, so a token that reports 81 to 255 is shown
-as one whose scale nothing knows.
+It is resolved from the bundled token list, then from the tokens the user tracks
+on the network the transaction is for, then, when that is the active network,
+from what the block explorer reported for the contract in the wallet's balances,
+which are the active network's only (`resolveTokenDecimals()` in
+`src/shared/approvalAmount.js`). Where none of them answers, the amount is not
+formatted: the line reads `5000000000 base units (decimals unknown)`. A guessed
+scale is not an approximation but a different number — 1,000 units of a
+6-decimal token formatted at 18 decimals reads `0.000000001` — on the screen
+whose only job is to state what is being authorized. Both amount paths of that
+screen take this rule: the ERC-20 `transfer`/`approve` line
+(`src/popup/views/approval.js`) and the swap's `Amount`, `Min. received`,
+`Moved from the sender` and `Permit2 allowance` lines and the `Paid to` line of
+a move into the router (`src/shared/uniswap.js`). The token permission warning
+on the signature screen takes the same rule for its amounts. An unbounded
+allowance or permit needs no scale to describe and is still shown as
+`Unlimited`. A source's answer counts only if it is a whole number from 0 to 80:
+`decimals()` returns a `uint8`, but `formatUnits()` cannot format more than 80
+decimal places, so a token that reports 81 to 255 is shown as one whose scale
+nothing knows.
 
 The rule holds only if nothing invents a scale UPSTREAM of it. Those three
 sources are read as authoritative, so a value written into one of them cannot be
@@ -1175,18 +1181,18 @@ number. They can read:
 - `Unlimited`: on the ERC-20 `Amount` line, an `approve` of the `uint256`
   maximum, an unbounded allowance. On the swap's `Amount` line, any amount at or
   above the `uint160` maximum, whichever step set the line: a `PERMIT2_PERMIT`
-  amount at that maximum, which is an unbounded permit, or a V2 or V3 exact-in,
-  V2 exact-out or `WRAP_ETH` amount that large, which is not an allowance. The
+  amount at that maximum, which is an unbounded permit, or a V2 or V3 exact-in
+  or exact-out or `WRAP_ETH` amount that large, which is not an allowance. The
   router's whole-balance value, `CONTRACT_BALANCE` (`2^255`), is one such
   amount.
-- `Up to <amount>`: the swap's `Amount` line, when the transaction has a V2
-  exact-out step, whichever step set the line, including the `WRAP_ETH` of a
+- `Up to <amount>`: the swap's `Amount` line, when the transaction has a V2 or
+  V3 exact-out step, whichever step set the line, including the `WRAP_ETH` of a
   swap paid in ETH and a `PERMIT2_PERMIT`. The swap spends at most that figure,
   not necessarily all of it; the wait, success and error screens show it with
   the same words. `Unlimited`, `All available (V4 open delta)` and
   `Whatever an earlier step sent to the pair (V2 already paid)` keep their
-  wording. When a V2 exact-out step sets `Min. received`, that line shows its
-  `amountOut`, the exact amount it buys.
+  wording. When a V2 or V3 exact-out step sets `Min. received`, that line shows
+  its `amountOut`, the exact amount it buys.
 - `All available (V4 open delta)`: the swap's `Amount` line, when the amount it
   shows is a V4 exact-in `amountIn` of zero. V4 reads that zero as "use the
   whole open delta", so the calldata states no quantity. Transaction Decoding
@@ -1240,12 +1246,40 @@ only when no earlier step set it. It finds each side by three rules:
    `Amount` or `Min. received`. A side they did not name is unknown, and the
    step sets it as unknown with no figure.
 
+Under each of these rules, when the user pays the step any of the input
+currency, its `Amount` is instead what the user pays it of that currency when
+the decoder knows that amount, and otherwise there is none (see Transaction
+Decoding). So a step whose USDT-for-USDC swap action could not be read, with a
+`SETTLE` of 400 USDT paid by the user, reads `Amount 400.0000 USDT`.
+
 A V4 step with no swap action sets only the sides its `SETTLE`, `SETTLE_ALL`,
 `TAKE` or `TAKE_ALL` names.
 
-An `UNWRAP_WETH` step makes `Token Out` ETH only when the output side is WETH,
-on mainnet or Sepolia, or when no step set the output side; a WETH
-`Min. received` figure then reads in ETH. Otherwise `Token Out` and
+An `UNWRAP_WETH` step makes `Token Out` ETH only when no step set the output
+side, or when the output side is WETH, on mainnet or Sepolia, that the step that
+set it paid to the router and that the router still holds when the `UNWRAP_WETH`
+runs (Transaction Decoding below gives what the router holds). The router
+unwraps only the WETH it holds, so WETH that step paid to the user, or to anyone
+else, stays WETH: a swap that pays the router WETH, then a swap that pays the
+user WETH, then an unwrap, shows WETH with the second swap's minimum. The
+minimum reads in ETH only when that step paid all its WETH to the router and
+every step between it and the `UNWRAP_WETH` is one the decoder read of these: a
+`PERMIT2_PERMIT`, a `BALANCE_CHECK_ERC20`, or a `SWEEP`, `TRANSFER`,
+`PAY_PORTION` or `PAY_PORTION_FULL_PRECISION` of a token other than WETH, but
+not of ETH to a WETH contract, which pays the router WETH. None of these can
+take WETH out of the router or pay anyone WETH; the decoder treats every other
+step as one that may. Otherwise the swap shows ETH with no minimum, as it does
+after a V4 step that `TAKE`s some of its WETH to the user and the rest to the
+router, or that pays the router WETH beside a payout the decoder cannot read,
+and with a WETH interface fee paid by `PAY_PORTION` before the `UNWRAP_WETH`:
+the decoder does not count how much of that step's minimum reaches the
+`UNWRAP_WETH`, nor read the `UNWRAP_WETH`'s own minimum. When an `UNWRAP_WETH`
+of that WETH pays the router, or its recipient cannot be read, the router may
+hold the ETH, and a later step may pay it out as WETH, as a `WRAP_ETH` of it to
+the user does: after any later step but those listed, the swap shows WETH with
+no minimum. Once the swap shows no minimum, or shows WETH this way, no later
+step, a later `UNWRAP_WETH` included, brings back the minimum or ETH; only a
+later step that sets the output side sets it anew. Otherwise `Token Out` and
 `Min. received` keep the output side's own token and figure, whether the swap
 was paid in ETH or in a token: a V2 exact-out swap that buys USDC and then
 unwraps the WETH it did not spend shows USDC. The token permission warning on
@@ -1369,6 +1403,19 @@ carries a `schemaVersion` — `STATE_SCHEMA_VERSION` in
 `saveState()` and the background's `updateState()` both do, so whichever context
 wrote last, the record says which build's shape it is in.
 
+Each write reads the record, changes it and writes it back, holding a lock from
+the read to the write: the browser's own (`navigator.locks`), taken through
+`withLock()` in `src/shared/browserApi.js`. Every page of the extension and its
+background share it, except a page in a Firefox private window, which Firefox
+gives locks of its own (see https://git.eeqj.de/sneak/AutistMask/issues/646).
+The popup's `saveState()`, the background's `updateState()` and the
+StateRecovery reset all take it, so among the pages and the background that
+share it, no write lands between another write's read and its write, where it
+would be lost. Chrome has it from version 69, older than any Chrome that runs a
+Manifest V3 extension, in pages and in the service worker; Firefox from version
+96, older than the 115 `manifest/firefox.json` declares. Where it is missing, a
+write fails rather than going ahead without it.
+
 Version 1 is the shape that shipped before versions existed, so a stored record
 with no `schemaVersion` is version 1 rather than a defect: it loads normally and
 is migrated in place by being stamped on the first write. An upgrade never shows
@@ -1524,9 +1571,11 @@ first screen that cannot be rendered from saved state, such as Send or AddToken,
 or at AddressToken for any token but the native one, because that token was
 picked on the previous network. The cut stack is saved with the switch, so a
 popup closed straight after it and reopened onto Settings lands in the same
-place. "Back" then renders the screen it lands on for the new network, except
-ConfirmTx, which keeps the network its transaction was reviewed on, and anything
-typed there and not saved, which belonged to the previous network, is dropped.
+place. "Back" then renders the screen it lands on for the new network, and
+anything typed there and not saved, which belonged to the previous network, is
+dropped. ConfirmTx, WaitTx, SuccessTx, ErrorTx and TransactionDetail are
+rendered instead for the network of the transaction they show: the network it
+was reviewed on for ConfirmTx, and the network it was sent on for the others.
 Without a wallet the stack is not cut, because it starts at Welcome, which shows
 nothing from a network.
 
@@ -1966,8 +2015,10 @@ view would leave a wallet one click from deletion.
 #### TransactionDetail (`transaction`)
 
 - **When**: User tapped a transaction row on Home, AddressDetail, or
-  AddressToken. Its etherscan links open the explorer of the network the
-  transaction was sent on, whichever network is active.
+  AddressToken. The screen describes the transaction on the network it was sent
+  on, whichever network is active: its block, network details, decoded details
+  and raw data are read from that network's Blockscout, the one Settings has for
+  it, and its etherscan links open that network's explorer.
 - **Elements** (grouped into logical blocks using light well containers; field
   labels are self-explanatory so groups have no headings):
     - "Transaction" heading, "Back" button
@@ -1975,7 +2026,11 @@ view would leave a wallet one click from deletion.
     - Type: transaction classification — one of: Native ETH Transfer, ERC-20
       Token Transfer, Swap, Token Approval, Contract Call, Contract Creation. A
       transfer with a token contract is an ERC-20 Token Transfer whatever symbol
-      the token reports.
+      the token reports. A call named `execute` or `multicall` is a Swap, here
+      and on its history row, only when it was sent to one of the Universal
+      Router addresses Uniswap publishes for the network it was sent on (see
+      Transaction Decoding); sent to any other contract, its history row shows
+      the method name and this line reads Contract Call.
     - Status: "Success" or "Failed"
     - From: blockie + color dot + full address (tap to copy) + etherscan link;
       ENS name if available
@@ -2039,8 +2094,11 @@ view would leave a wallet one click from deletion.
       none, and the tokens tracked on that network, and sends `chainChanged`
       with the new chain id to every open tab. A token is tracked only on the
       network it was added on, because a contract address names a token on one
-      network only. Choosing the network already active changes nothing and
-      sends nothing
+      network only. Switching also clears every address's balances. A balance
+      refresh, by the popup or the background, stores what it fetched only if
+      the stored network is still the one it fetched on when it returns, so the
+      previous network's balances never reach the new one. Choosing the network
+      already active changes nothing and sends nothing
     - Ethereum RPC: endpoint URL input + "Save" button (validated against
       `eth_chainId` before being saved)
     - Blockscout API: endpoint URL input + "Save" button (validated against
@@ -2369,10 +2427,11 @@ view would leave a wallet one click from deletion.
       transaction"
     - Decoded action (if calldata is recognized): action name, token details,
       amounts, what each swap step spends that the `Amount` line does not give,
-      what each `PERMIT2_TRANSFER_FROM` moves and where to, steps, deadline, and
-      unless a swap pays only the From address, a `Paid to` line for each other
-      address it pays, or saying that a token stays in the router or who it pays
-      is unknown (see Transaction Decoding)
+      what each `PERMIT2_TRANSFER_FROM` moves and where to, what each
+      `PERMIT2_PERMIT` whose amount is not the `Amount` figure lets its spender
+      take, steps, deadline, and unless a swap pays only the From address, a
+      `Paid to` line for each other address it pays, or saying that a token
+      stays in the router or who it pays is unknown (see Transaction Decoding)
     - From: color dot + full address + etherscan link
     - Contract: color dot + full address + etherscan link, token symbol label if
       known; for a contract creation, the same sentence as on WaitTx
@@ -2385,6 +2444,11 @@ view would leave a wallet one click from deletion.
     - Raw data: full calldata displayed inline (shown if present)
     - Password input and an error line
     - "Confirm" / "Reject" buttons
+- **Behavior**: Every etherscan link on the screen opens the explorer of the
+  network the transaction was populated on, whichever network is active. The
+  Value and Network fee lines each give the USD value of the exact amount at the
+  price on that network, as on ConfirmTx: none for a testnet transaction or one
+  on a chain id that names no network.
 - **Transitions**:
     - "Confirm" (correct password) → decrypts and signs the transaction it was
       shown, exactly as shown, hands the signed transaction to the background to
@@ -2993,31 +3057,37 @@ Currently supported:
   "Swap USDT → ETH"), token addresses, amounts, execution steps, and deadline.
   The swap summary is shown only for a transaction sent to one of the Universal
   Router addresses Uniswap publishes for the network: on TxApproval the network
-  the transaction is for, on TransactionDetail the active network. The same
-  calldata sent to any other address is shown as raw data. Decodes Permit2,
-  V2/V3/V4 swaps, wrap/unwrap, and balance checks. A V4 swap action is read only
-  in the parameter shape deployed on mainnet and Sepolia, not in the newer one
-  on `v4-periphery` `main`, which adds a `minHopPriceX36` field. An action in
-  any other shape is not read, and its step is listed as
-  `V4 Swap (could not be decoded)`. Each step is named and read as the command
-  that the release of the router at that address runs for its command type, as
-  that release's `contracts/libraries/Commands.sol` names it. The decoder reads
-  the type from the command byte with the mask that router uses: `0x1f` for
-  `UniversalRouterV1`, `0x3f` for `UniversalRouterV1_2_V2Support` and
-  `UniversalRouterV2`, and `0x7f` for `UniversalRouterV2_1_1` and
-  `UniversalRouterV2_1_2`. The allow-revert flag (`0x80`) therefore does not
-  change the command a step is read as. Releases run different commands for some
-  types: on `UniversalRouterV1` and `UniversalRouterV1_2_V2Support`, `0x10` to
-  `0x13` are NFT commands, where the later routers run `V4_SWAP`,
-  `V3_POSITION_MANAGER_PERMIT`, `V3_POSITION_MANAGER_CALL` and
-  `V4_INITIALIZE_POOL`. The decoder does not read those routers' NFT commands,
-  and lists each by its name there, for example `Seaport` for `SEAPORT` (`0x10`
-  on `UniversalRouterV1`). A type a release names no command for is listed by
-  its number, for example `Command 0x0e` on `UniversalRouterV1`, which has no
-  `BALANCE_CHECK_ERC20` and reverts on it. The router reverts the whole
-  transaction when a step fails, unless the step's command byte has that flag
-  set and its command is one the router lets fail, as each release's
-  `contracts/base/Dispatcher.sol` shows: on `UniversalRouterV2`,
+  the transaction is for, on TransactionDetail the network it was sent on. The
+  same calldata sent to any other address is shown as raw data. Decodes Permit2,
+  V2/V3/V4 swaps, wrap/unwrap, and balance checks. A V3 swap step's path is read
+  as the router reads it: a `V3_SWAP_EXACT_IN` path runs from the token it
+  spends to the token it buys, and a `V3_SWAP_EXACT_OUT` path from the token it
+  buys to the token it spends, so that step's input token is its path's last
+  token and its output token the first. The router reads a path as one token
+  address followed by whole hops of a 3-byte fee and a token address, and
+  ignores any bytes after the last hop, so the decoder does not read a path with
+  such bytes. A V4 swap action is read only in the parameter shape deployed on
+  mainnet and Sepolia, not in the newer one on `v4-periphery` `main`, which adds
+  a `minHopPriceX36` field. An action in any other shape is not read, and its
+  step is listed as `V4 Swap (could not be decoded)`. Each step is named and
+  read as the command that the release of the router at that address runs for
+  its command type, as that release's `contracts/libraries/Commands.sol` names
+  it. The decoder reads the type from the command byte with the mask that router
+  uses: `0x1f` for `UniversalRouterV1`, `0x3f` for
+  `UniversalRouterV1_2_V2Support` and `UniversalRouterV2`, and `0x7f` for
+  `UniversalRouterV2_1_1` and `UniversalRouterV2_1_2`. The allow-revert flag
+  (`0x80`) therefore does not change the command a step is read as. Releases run
+  different commands for some types: on `UniversalRouterV1` and
+  `UniversalRouterV1_2_V2Support`, `0x10` to `0x13` are NFT commands, where the
+  later routers run `V4_SWAP`, `V3_POSITION_MANAGER_PERMIT`,
+  `V3_POSITION_MANAGER_CALL` and `V4_INITIALIZE_POOL`. The decoder does not read
+  those routers' NFT commands, and lists each by its name there, for example
+  `Seaport` for `SEAPORT` (`0x10` on `UniversalRouterV1`). A type a release
+  names no command for is listed by its number, for example `Command 0x0e` on
+  `UniversalRouterV1`, which has no `BALANCE_CHECK_ERC20` and reverts on it. The
+  router reverts the whole transaction when a step fails, unless the step's
+  command byte has that flag set and its command is one the router lets fail, as
+  each release's `contracts/base/Dispatcher.sol` shows: on `UniversalRouterV2`,
   `UniversalRouterV2_1_1` and `UniversalRouterV2_1_2`, `PERMIT2_PERMIT`,
   `PERMIT2_PERMIT_BATCH`, `BALANCE_CHECK_ERC20`, `V3_POSITION_MANAGER_PERMIT`,
   `V3_POSITION_MANAGER_CALL`, `V4_INITIALIZE_POOL`, `V4_POSITION_MANAGER_CALL`
@@ -3080,40 +3150,42 @@ Currently supported:
   as a swap paid in ETH does, but only when that amount is not
   `CONTRACT_BALANCE` and the router held no WETH from an earlier step when the
   `WRAP_ETH` ran: after two `WRAP_ETH`s of 0.5 ETH into the router, a swap of 1
-  WETH from it reads as leaving the WETH there. A `SETTLE` of `OPEN_DELTA`
-  (zero), and a `SETTLE_ALL`, pay only what the step still owes of their token
-  when they run. The decoder takes that to be the amounts the step's swap
-  actions state they spend of that token only when every action in the step
-  could be read, every swap action names the token it spends and the token it
-  buys (a swap action with an empty path swaps nothing), the `SETTLE` or
-  `SETTLE_ALL` is the step's only `SETTLE` or `SETTLE_ALL` of that token and
-  comes after every swap action, no swap action buys that token, no `TAKE`,
-  `TAKE_ALL` or `TAKE_PORTION` in the step takes it (a `TAKE` of a stated amount
-  adds to what the step owes), and the swap actions that spend it state a
-  quantity together; otherwise it does not know the amount, and such a `SETTLE`
-  from the router counts as spending nothing. So the rest of a V4 `SETTLE` of
-  more than its swap spends, taken to the router, the WETH of a `WRAP_ETH`, and
-  a token a swap pays the router on the way to the output, each stays in the
-  router when later steps do not spend all of it, where anyone can take it in a
-  later transaction. The router sends ETH as written, so a `TRANSFER` of
-  `CONTRACT_BALANCE` of ETH always reverts and pays out nothing. A step paying a
-  token to the V2 pair that the very next step spends, as a V2 exact-in of that
-  token whose `amountIn` is `ALREADY_PAID` (zero) or `CONTRACT_BALANCE`, is a
-  hop, not a payout: Uniswap's mixed routes pay the next V2 pair directly, and
-  the router enforces that swap's own minimum. The decoder checks that the
-  address paid is that pair, deriving it from the V2 factory and pair init code
-  hash the network's routers were deployed with and the first two tokens of that
-  step's path; a payment to any other address is named. (Sepolia's
-  `UniversalRouterV1_2_V2Support` was deployed with placeholders for both
-  values, so no V2 swap step can succeed on that router.) Every other payment
-  counts, in whichever step and of whatever token, a share of the output
-  included: an interface fee paid to another address by `PAY_PORTION`,
-  `TRANSFER` or `TAKE_PORTION` is named, and the minimum reads `Min. paid out`,
-  because the swap's minimum includes the fee. The minimum reads `Min. received`
-  only when some step pays the transaction's sender (the From address on
-  TxApproval, the sender the explorer reports on TransactionDetail) and no
-  `Paid to` line is shown. `Paid to` lines after `Token Out` name each other
-  address paid; one reads
+  WETH from it reads as leaving the WETH there. A V2 or V3 exact-out step paid
+  from the router spends an amount the calldata does not state, at most its
+  `amountInMax`, so the decoder counts it as spending nothing the router holds.
+  A `SETTLE` of `OPEN_DELTA` (zero), and a `SETTLE_ALL`, pay only what the step
+  still owes of their token when they run. The decoder takes that to be the
+  amounts the step's swap actions state they spend of that token only when every
+  action in the step could be read, every swap action names the token it spends
+  and the token it buys (a swap action with an empty path swaps nothing), the
+  `SETTLE` or `SETTLE_ALL` is the step's only `SETTLE` or `SETTLE_ALL` of that
+  token and comes after every swap action, no swap action buys that token, no
+  `TAKE`, `TAKE_ALL` or `TAKE_PORTION` in the step takes it (a `TAKE` of a
+  stated amount adds to what the step owes), and the swap actions that spend it
+  state a quantity together; otherwise it does not know the amount, and such a
+  `SETTLE` from the router counts as spending nothing. So the rest of a V4
+  `SETTLE` of more than its swap spends, taken to the router, the WETH of a
+  `WRAP_ETH`, and a token a swap pays the router on the way to the output, each
+  stays in the router when later steps do not spend all of it, where anyone can
+  take it in a later transaction. The router sends ETH as written, so a
+  `TRANSFER` of `CONTRACT_BALANCE` of ETH always reverts and pays out nothing. A
+  step paying a token to the V2 pair that the very next step spends, as a V2
+  exact-in of that token whose `amountIn` is `ALREADY_PAID` (zero) or
+  `CONTRACT_BALANCE`, is a hop, not a payout: Uniswap's mixed routes pay the
+  next V2 pair directly, and the router enforces that swap's own minimum. The
+  decoder checks that the address paid is that pair, deriving it from the V2
+  factory and pair init code hash the network's routers were deployed with and
+  the first two tokens of that step's path; a payment to any other address is
+  named. (Sepolia's `UniversalRouterV1_2_V2Support` was deployed with
+  placeholders for both values, so no V2 swap step can succeed on that router.)
+  Every other payment counts, in whichever step and of whatever token, a share
+  of the output included: an interface fee paid to another address by
+  `PAY_PORTION`, `TRANSFER` or `TAKE_PORTION` is named, and the minimum reads
+  `Min. paid out`, because the swap's minimum includes the fee. The minimum
+  reads `Min. received` only when some step pays the transaction's sender (the
+  From address on TxApproval, the sender the explorer reports on
+  TransactionDetail) and no `Paid to` line is shown. `Paid to` lines after
+  `Token Out` name each other address paid; one reads
   `The bridge, which pays the deposit's recipient on another network` for a
   bridge deposit; one reads, for example,
   `The router, 2000.0000 USDT from the sender (later steps may not spend all of it)`
@@ -3127,72 +3199,102 @@ Currently supported:
   `Unknown (not named in the calldata)`. Wherever there is a `Paid to` line, the
   minimum reads `Min. paid out`. The `Amount` line gives the total the steps
   take of `Token In`, from the step that sets the input side on: the first V2 or
-  V3 exact-in, V2 exact-out, `WRAP_ETH` or V4 swap step that names an input
-  token or amount. A V4 step with a swap action sets the input side when no
-  earlier step set it, even when it names neither (see Display Consistency).
-  That step counts its own amount, whoever pays it: a V2 exact-out step its
-  `amountInMax`, and a V4 swap step the `amountIn` of the swap action that
-  spends its input currency. Each later V2 or V3 exact-in or V2 exact-out step
-  whose `payerIsUser` is true takes its amount, found in the same way, from the
-  user's wallet. So does every V4 step but the one that sets the input side,
-  with a swap action or without: it takes what its `SETTLE`s paid by the user
-  (`payerIsUser` true) and its `SETTLE_ALL`s pay, for each token on its own. A
-  `SETTLE` of any amount but `OPEN_DELTA` pays that amount, and a `SETTLE` of
-  `OPEN_DELTA` or a `SETTLE_ALL` pays what the step owes, as above. A later step
-  paid from the router spends what the router holds and takes nothing, and so
-  does a V2 exact-in whose `amountIn` is `ALREADY_PAID`. A later take of
-  `Token In` is added to the total while both are quantities: a V3 exact-in of
-  600 USDT and a V2 exact-in of 400 USDT, both paid by the user, read
-  `1000.0000 USDT`. When the decoder does not know a take's amount, the total is
-  not known and there is no `Amount` line. `Token In` is the token of the last
-  `PERMIT2_PERMIT` the decoder reads, when there is one. Its amount, `Unlimited`
-  included, stands as the `Amount` figure in place of the total only in the
-  plain shape of Uniswap's own routes: it is the only `PERMIT2_PERMIT`, its
-  spender is the router, the router may not let it fail, no step before it takes
-  its token or a token the decoder does not know, and no `PERMIT2_PERMIT_BATCH`
-  comes after it. Permit2 then lets the router take no more of the token than
-  that amount, so the permit covers every take of it. In any other case the line
-  gives the total, as with no permit. When the step that sets the input side
-  spends a token other than the permit's, or one the decoder does not know, its
-  amount gets lines of its own and the total has no figure to start from: unless
-  the permit's amount stands there is no `Amount` line, and each take of the
-  permit's token gets lines of its own. Each take the total does not count gives
-  three lines after the `Amount` line (after `Token In` when there is none): one
-  of a token other than `Token In`; one of `Token In` after an amount that is
-  not a quantity (a V4 open delta, `ALREADY_PAID`, which keep their wording on
-  the `Amount` line, or no stated amount, as of a V4 exact-out step); and one
-  whose amount the decoder does not know. They come in step order, the step that
-  sets the input side first when it has them: `Moved from the sender`, its
-  amount, worded as the `Amount` line words one, or
-  `Unknown (could not be decoded)` when the decoder does not know it;
-  `Token moved`, giving the token's address as the `Token In` line does; and
+  V3 exact-in or exact-out, `WRAP_ETH` or V4 swap step that names an input token
+  or amount. A V4 step with a swap action sets the input side when no earlier
+  step set it, even when it names neither (see Display Consistency). That step
+  counts its own amount, whoever pays it: a V2 or V3 exact-out step its
+  `amountInMax`, and a V4 step what it takes of its input token from the user's
+  wallet, as below, or, when the user pays it none of that token, the `amountIn`
+  of the swap action that spends it. Each later V2 or V3 exact-in or exact-out
+  step whose `payerIsUser` is true takes its amount, found in the same way, from
+  the user's wallet. Every V4 step, with a swap action or without, takes from
+  the user's wallet what its `SETTLE`s paid by the user (`payerIsUser` true) and
+  its `SETTLE_ALL`s pay, for each token on its own; what the step that sets the
+  input side takes of any other token counts as a later step's take. A `SETTLE`
+  of any amount but `OPEN_DELTA` pays that amount, and a `SETTLE` of
+  `OPEN_DELTA` or a `SETTLE_ALL` pays what the step owes, as above. So a V4 step
+  that swaps 400 USDT, with a `SETTLE` of 5,000 USDT paid by the user and the
+  rest taken to another address, reads `5000.0000 USDT`. A later step paid from
+  the router spends what the router holds and takes nothing, and so does a V2
+  exact-in whose `amountIn` is `ALREADY_PAID`. A later take of `Token In` is
+  added to the total while both are quantities: a V3 exact-in of 600 USDT and a
+  V2 exact-in of 400 USDT, both paid by the user, read `1000.0000 USDT`. When
+  the decoder does not know a take's amount, the total is not known and there is
+  no `Amount` line. A `PERMIT2_PERMIT` names `Token In` only when its amount,
+  `Unlimited` included, stands as the `Amount` figure in place of the total,
+  which it does only in the plain shape of Uniswap's own routes: it comes before
+  the step that sets the input side, it is the only `PERMIT2_PERMIT` in the
+  transaction, its spender is the router, the router may not let it fail, no
+  step before it takes its token or a token the decoder does not know, and the
+  decoder reads every step after it in full. Permit2 then lets the router take
+  no more of the token than that amount, so the permit covers every take of it.
+  A step the decoder does not read in full may raise what Permit2 lets the
+  router take, as a `PERMIT2_PERMIT_BATCH` can: a command the decoder does not
+  read (listed at the end of this section), a step whose input it cannot read,
+  in whole or in part, and a step it fails on. Every other `PERMIT2_PERMIT`,
+  before the step that sets the input side or after it, leaves `Token In` and
+  the `Amount` line as they read with no permit: a permit of 5,000 DAI to
+  another address and then a V3 exact-in of 600 USDT read `Swap USDT → USDC`
+  with `Amount 600.0000 USDT`, and so do that exact-in and then a permit of
+  5,000 DAI to the router. When a permit's amount stands and the step that sets
+  the input side spends a token other than the permit's, or one the decoder does
+  not know, that step's amount gets lines of its own, unless it states no amount
+  and the user pays it none of its input token. Each take the total does not
+  count gives three lines after the `Amount` line (after `Token In` when there
+  is none): one of a token other than `Token In`; one of `Token In` after an
+  amount that is not a quantity (a V4 open delta, `ALREADY_PAID`, which keep
+  their wording on the `Amount` line, or no stated amount, as of a V4 exact-out
+  step); and one whose amount the decoder does not know. When the step that sets
+  the input side states no amount, the user pays it some of its input token, and
+  there is no `Amount` line, that step gets them too whenever another take's
+  lines give a figure, or a `PERMIT2_TRANSFER_FROM` of its token gives one, on
+  the lines below or, into the router, on its `Paid to` line, so that figure
+  cannot read as all that leaves. When it states no amount and the user pays it
+  none of its input token, as when the router pays it, that step takes none of
+  that token from the user's wallet and never gets them, with a permit or
+  without. They come in step order, the step that sets the input side first when
+  it has them: `Moved from the sender`, its amount, worded as the `Amount` line
+  words one, or `Unknown (could not be decoded)` when the decoder does not know
+  it; `Token moved`, giving the token's address as the `Token In` line does; and
   `Moved to`, which reads `The swap step that spends it`. A token the decoder
   does not know gives the `Moved from the sender` line alone. A step may also
-  take from the user's wallet what the decoder did not read: a V4 step, other
-  than the one that sets the input side, whose input or one of whose `SETTLE`s
-  or `SETTLE_ALL`s it cannot read, which the router still runs; a V2 or V3
-  exact-in or V2 exact-out step or a `PERMIT2_TRANSFER_FROM` whose input it
-  cannot read; and every `PERMIT2_TRANSFER_FROM_BATCH`. 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.
-  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
+  take from the user's wallet what the decoder did not read: a V4 step whose
+  input or one of whose `SETTLE`s or `SETTLE_ALL`s it cannot read, which the
+  router still runs; a V2 or V3 exact-in or exact-out step or a
+  `PERMIT2_TRANSFER_FROM` whose input it cannot read, such as a V3 step whose
+  path is shorter than one token address or has bytes after its last hop; every
+  `PERMIT2_TRANSFER_FROM_BATCH`; every `EXECUTE_SUB_PLAN`, wherever it stands;
+  and every step it fails on. Each such step gives one `Moved from the sender`
+  line among those, reading `Unknown (could not be decoded)`. That line, or any
+  line for a token the decoder does not know, leaves no `Amount` line, whose
+  figure might be too low, and such a step before a `PERMIT2_PERMIT` keeps the
+  permit's amount from standing. Then each `PERMIT2_TRANSFER_FROM` but one into
+  the router, in step order, gives three lines: `Moved from the sender`, the
+  amount it moves, for example `1000000.0000 USDT`; `Token moved`, giving the
+  token's address as the `Token In` line does; and `Moved to`, which reads
   `The V2 pair the next swap spends` for a hop and `The sender` for `address(1)`
   on every router but `UniversalRouterV1`, and otherwise gives the address. A
   move into the router needs none of them, because its `Paid to` line and
   `Token moved into the router` line already give the amount, the token and
-  where it goes, and so its amount is shown once. These lines change neither the
-  `Paid to` lines nor the minimum's label. A step goes unread when its recipient
-  does not decode as an address, or when it is a command the decoder does not
-  read: every command other than `PERMIT2_PERMIT`, `PERMIT2_TRANSFER_FROM`,
-  `V2_SWAP_EXACT_IN`, `V2_SWAP_EXACT_OUT`, `V3_SWAP_EXACT_IN`, `V4_SWAP`,
-  `SWEEP`, `TRANSFER`, `PAY_PORTION`, `PAY_PORTION_FULL_PRECISION`,
-  `ACROSS_V4_DEPOSIT_V3`, `WRAP_ETH`, `UNWRAP_WETH` and `BALANCE_CHECK_ERC20`
-  (`V3_SWAP_EXACT_OUT`, `PERMIT2_TRANSFER_FROM_BATCH`, `EXECUTE_SUB_PLAN` and
-  the NFT commands among them), or a type its release names no command for.
+  where it goes, and so its amount is shown once. Every `PERMIT2_PERMIT` whose
+  amount does not stand as the `Amount` figure, before the step that sets the
+  input side or after it, gives three lines, in step order, after those for each
+  `PERMIT2_TRANSFER_FROM`: `Permit2 allowance`, its amount, for example
+  `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. These lines change neither the `Paid to`
+  lines nor the minimum's label. A step goes unread when its recipient does not
+  decode as an address, when it is a V3 swap step whose path is shorter than one
+  token address or has bytes after its last hop, or when it is a command the
+  decoder does not read: every command other than `PERMIT2_PERMIT`,
+  `PERMIT2_TRANSFER_FROM`, `V2_SWAP_EXACT_IN`, `V2_SWAP_EXACT_OUT`,
+  `V3_SWAP_EXACT_IN`, `V3_SWAP_EXACT_OUT`, `V4_SWAP`, `SWEEP`, `TRANSFER`,
+  `PAY_PORTION`, `PAY_PORTION_FULL_PRECISION`, `ACROSS_V4_DEPOSIT_V3`,
+  `WRAP_ETH`, `UNWRAP_WETH` and `BALANCE_CHECK_ERC20`
+  (`PERMIT2_TRANSFER_FROM_BATCH`, `EXECUTE_SUB_PLAN` and the NFT commands among
+  them), or a type its release names no command for.
 
 ### Non-Goals Forever
 

package.json

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

src/background/index.js

@@ -1379,6 +1379,13 @@ const RECENT_BALANCE_REFRESH_MS = Math.floor(BALANCE_REFRESH_PERIOD_MS / 2);
 // balances that came back — by address, onto whatever storage holds NOW.
 // Applying by address rather than writing the array back is what keeps a
 // wallet or address added, renamed or deleted during the round trip.
+//
+// Nothing is applied when the network stored NOW is not the one the refresh
+// ran on. A network switch during the round trip cleared every address's
+// balances (applyChainSwitchFields()), and the previous network's must not come
+// back over them (https://git.eeqj.de/sneak/AutistMask/issues/577).
+// lastBalanceRefresh is left as the switch set it, so the next tick refreshes
+// the new network.
 async function backgroundRefresh() {
     const s = await getState();
     const now = Date.now();
@@ -1402,6 +1409,7 @@ async function backgroundRefresh() {
     }
 
     await updateState((fresh) => {
+        if (fresh.networkId !== s.networkId) return;
         for (const wallet of fresh.wallets) {
             for (const addr of wallet.addresses || []) {
                 const got = refreshed.get(String(addr.address).toLowerCase());

src/background/state.js

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

src/popup/index.html

@@ -90,7 +90,7 @@
                 <div id="add-wallet-section-mnemonic">
                     <!-- The die button shares the instruction's row: on a row
                          of its own it pushes Import below the fold at
-                         360x600. -->
+                         396x600. -->
                     <div class="mb-2 flex justify-between items-start gap-2">
                         <p>
                             Enter your 12 or 24 word recovery phrase below, or
@@ -212,7 +212,7 @@
                     />
                 </div>
                 <!-- The error line sits beside Import, not above it: at
-                     360x600 the button already starts near the bottom of
+                     396x600 the button already starts near the bottom of
                      the popup, and a line of its own would push it below
                      the fold. The longest error fits on one line here. -->
                 <div class="flex items-center gap-2">

src/popup/index.js

@@ -68,23 +68,54 @@ let refreshInFlight = false;
 // the recovery screen: there is no profile left to refresh.
 let refreshTimer = null;
 
+// The refresh writes into a copy of the wallets. Inside the save, under the
+// lock, its results are copied onto the address records in `state` only if the
+// network it ran on is still the active one, on this page and in the stored
+// record; the background's switch, after the user approves a site's request,
+// changes only the stored record. A switch while the refresh ran cleared every
+// address's balances (applyChainSwitchFields() in
+// src/shared/chainSwitchFields.js), and the previous network's must not come
+// back over them (https://git.eeqj.de/sneak/AutistMask/issues/577). A dropped
+// refresh is not recorded as done. Results are copied by address, so an address
+// added or removed meanwhile is left as it is.
 async function doRefreshAndRender() {
     if (refreshInFlight) return;
     refreshInFlight = true;
     try {
+        const networkId = state.networkId;
+        const wallets = structuredClone(state.wallets);
         await Promise.all([
             refreshPrices(),
             refreshBalances(
-                state.wallets,
+                wallets,
                 state.rpcUrl,
                 state.blockscoutUrl,
                 state.trackedTokens,
-                state.networkId,
+                networkId,
                 pageClosed.signal,
             ),
         ]);
-        state.lastBalanceRefresh = Date.now();
-        await saveState();
+        const refreshed = new Map();
+        for (const wallet of wallets) {
+            for (const addr of wallet.addresses) {
+                refreshed.set(addr.address, addr);
+            }
+        }
+        await saveState((stored) => {
+            if (state.networkId !== networkId) return false;
+            if (stored.networkId !== networkId) return false;
+            for (const wallet of state.wallets) {
+                for (const addr of wallet.addresses) {
+                    const got = refreshed.get(addr.address);
+                    if (!got) continue;
+                    for (const key of ["balance", "ensName", "tokenBalances"]) {
+                        if (got[key] !== undefined) addr[key] = got[key];
+                    }
+                }
+            }
+            state.lastBalanceRefresh = Date.now();
+            return true;
+        });
         renderWalletList();
     } catch (e) {
         // Every call site fires this and walks away — the boot below, the ten
@@ -220,7 +251,7 @@ async function widenApprovalWindow() {
 async function init() {
     // First, before anything can save: showView() saves on every navigation
     // without awaiting, so a save that fails from here on has somewhere to be
-    // reported rather than being swallowed by the save queue
+    // reported rather than reaching only the console
     // (https://git.eeqj.de/sneak/AutistMask/issues/362). Registered ahead of
     // the approval-window branch below too, since that window saves as well.
     //

src/popup/viewRouter.js

@@ -145,15 +145,15 @@ function isRenderablePendingTx(value) {
 
 // The stored transaction transactionDetail.render() shows. contractAddress is
 // optional on an ETH transfer, and reaches addressDotHtml() when it is there.
-// `chainId` picks the network whose explorer the links open, so when it is
-// there it has to name one.
+// `chainId` picks the network whose explorer the links open and whose
+// Blockscout the transaction is read from, so it has to name one.
 function isRenderableTx(value) {
     return (
         isRecord(value) &&
         isAddressText(value.from) &&
         isAddressText(value.to) &&
         (!value.contractAddress || isAddressText(value.contractAddress)) &&
-        (!value.chainId || SUPPORTED_CHAIN_IDS.has(value.chainId))
+        SUPPORTED_CHAIN_IDS.has(value.chainId)
     );
 }
 

src/popup/views/approval.js

@@ -11,6 +11,7 @@ const {
     onViewLeave,
     formatFee,
     tokenLabel,
+    tokenSourcesByChainId,
 } = require("./helpers");
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const {
@@ -57,9 +58,15 @@ const { notify, runtimeApi, sendMessage } = require("../../shared/browserApi");
 
 const erc20Iface = new Interface(ERC20_ABI);
 
-function approvalAddressHtml(address) {
+// The link opens the explorer of the network with `chainId`, or of the active
+// network when none is given. A chain id that names no network has no
+// explorer, so the address is drawn without a link.
+function approvalAddressHtml(address, chainId) {
     const title = addressTitle(address, state.wallets);
-    return renderAddressHtml(address, { title });
+    if (chainId && !networkByChainId(chainId)) {
+        return renderAddressHtml(address, { title, noLink: true });
+    }
+    return renderAddressHtml(address, { title, chainId });
 }
 
 // The amount line for a decoded ERC-20 call. With a known scale it is the
@@ -85,13 +92,12 @@ function tokenAmountText(rawAmount, decimals, symbol) {
 function decodeCalldata(data, toAddress, chainId, fromAddress) {
     if (!data || data === "0x" || data.length < 10) return null;
 
-    // Where a token's scale is looked for, for every decoder below: the ERC-20
-    // amount line and the swap's Amount and Min. received lines resolve it the
-    // same way, and refuse to format the same way when it is nowhere.
-    const decimalsSources = {
-        trackedTokens: state.trackedTokens,
-        wallets: state.wallets,
-    };
+    // Where a token's name and scale are looked for, for every decoder below:
+    // what the wallet knows of the tokens on the network with `chainId`, which
+    // need not be the active one. The ERC-20 amount line and the swap's Amount
+    // and Min. received lines resolve the scale the same way, and refuse to
+    // format the same way when it is nowhere.
+    const decimalsSources = tokenSourcesByChainId(chainId);
 
     // Try ERC-20 (approve / transfer)
     try {
@@ -225,10 +231,11 @@ function showTxFee(approvedTx) {
     const feePerGas = BigInt(approvedTx.maxFeePerGas || approvedTx.gasPrice);
     // Through formatFee(), as the confirmation screen's fee is, so the same
     // fee reads the same on both. In the native currency of the network shown
-    // above, as the value is.
+    // above, and at the price on it, as the value is.
     $("approve-tx-fee").textContent = formatFee(
         gasLimit * feePerGas,
         nativeCurrencyByChainId(approvedTx.chainId),
+        approvedTx.chainId,
     );
 
     let detail =
@@ -261,10 +268,7 @@ function showTxApproval(details) {
 
     const toAddr = approvedTx.to;
     const ethValue = formatEther(approvedTx.value || "0");
-    const sources = {
-        trackedTokens: state.trackedTokens,
-        wallets: state.wallets,
-    };
+    const sources = tokenSourcesByChainId(approvedTx.chainId);
 
     // Build txInfo for status screens
     pendingTxDetails = {
@@ -341,27 +345,35 @@ function showTxApproval(details) {
         };
     }
 
+    // Every address link on this screen opens the explorer of the network the
+    // transaction is for, which the Network line names, whichever network is
+    // active.
     $("approve-tx-origin").textContent = details.origin;
-    $("approve-tx-from").innerHTML = approvalAddressHtml(details.approvedFrom);
+    $("approve-tx-from").innerHTML = approvalAddressHtml(
+        details.approvedFrom,
+        approvedTx.chainId,
+    );
 
-    // Show token symbol next to contract address if known
-    const symbol = toAddr ? tokenLabel(toAddr) : null;
+    // Show token symbol next to contract address if known on the network the
+    // transaction is for
+    const symbol = toAddr ? tokenLabel(toAddr, approvedTx.chainId) : null;
     if (toAddr) {
         let toHtml = "";
         if (symbol) {
             toHtml += `<div class="font-bold mb-1">${escapeHtml(symbol)}</div>`;
         }
-        toHtml += approvalAddressHtml(toAddr);
+        toHtml += approvalAddressHtml(toAddr, approvedTx.chainId);
         $("approve-tx-to").innerHTML = toHtml;
     } else {
         $("approve-tx-to").innerHTML = escapeHtml(CONTRACT_CREATION_TEXT);
     }
 
-    const ethValueFormatted = formatTxValue(
-        formatEther(approvedTx.value || "0"),
-    );
-    const ethPrice = getPrice("ETH");
-    const ethUsd = ethPrice ? parseFloat(ethValueFormatted) * ethPrice : null;
+    const ethValueFormatted = formatTxValue(ethValue);
+    // Priced from the exact value, not the four-decimal figure, at the price
+    // on the network the transaction is for, as the confirmation screen prices
+    // its amount, so the same value reads the same on both.
+    const ethPrice = getPrice("ETH", approvedTx.chainId);
+    const ethUsd = ethPrice ? parseFloat(ethValue) * ethPrice : null;
     const usdStr = formatUsd(ethUsd);
     // In the native currency of the network the transaction is for, which the
     // Network line names, not the active network's: the active network can
@@ -388,9 +400,12 @@ function showTxApproval(details) {
             detailsHtml += `<div class="text-muted">${escapeHtml(d.label)}</div>`;
             if (d.address) {
                 if (d.isToken) {
-                    detailsHtml += `<div class="font-bold">${escapeHtml(tokenLabel(d.address) || "Unknown token")}</div>`;
+                    detailsHtml += `<div class="font-bold">${escapeHtml(tokenLabel(d.address, approvedTx.chainId) || "Unknown token")}</div>`;
                 }
-                detailsHtml += approvalAddressHtml(d.address);
+                detailsHtml += approvalAddressHtml(
+                    d.address,
+                    approvedTx.chainId,
+                );
             } else {
                 detailsHtml += `<div class="font-bold">${escapeHtml(d.value)}</div>`;
             }

src/popup/views/helpers.js

@@ -1,4 +1,7 @@
-// Shared DOM helpers used by all views.
+// Helpers the views in this directory share: showing a view and going back,
+// error and flash lines and the warning banners, formatting of amounts, fees,
+// balances, addresses and dates, the RPC and Blockscout URLs, node and tokens
+// of the network a chain id names, explorer links, and click-to-copy.
 //
 // Escaping rule for every view in this directory, since they all build
 // markup by concatenation: any VALUE interpolated into an innerHTML string
@@ -297,15 +300,30 @@ function nativeCurrency() {
     return currentNetwork().nativeCurrency;
 }
 
-// The symbol shown for a token line, resolved from the bundled list, the
-// tokens the user tracks, and the explorer's report — the same chain the
-// amount line's scale comes from. Null when no source names one, so the token
-// lines keep saying `Unknown token` for a token nothing knows.
-function tokenLabel(address) {
-    return resolveTokenSymbol(address, {
-        trackedTokens: state.trackedTokens,
-        wallets: state.wallets,
-    });
+// What the wallet knows of the tokens on the network with this chain id, or
+// on the active network when no chain id is given, as the `sources` that
+// resolveTokenSymbol() and resolveTokenDecimals() take. A contract address
+// names a token on one network only, and every token balance held is the
+// active network's, so another network gets the tokens tracked on it
+// (state.networkTrackedTokens, see applyChainSwitchFields()) and no balances.
+function tokenSourcesByChainId(chainId) {
+    const net = chainId ? networkByChainId(chainId) : currentNetwork();
+    if (net && net.id === state.networkId) {
+        return { trackedTokens: state.trackedTokens, wallets: state.wallets };
+    }
+    return {
+        trackedTokens: (net && state.networkTrackedTokens[net.id]) || [],
+        wallets: [],
+    };
+}
+
+// The symbol shown for a token line on the network with `chainId`, or on the
+// active network when none is given: from the bundled list, the tokens the
+// user tracks, and the explorer's report, the sources the amount line's scale
+// comes from. Null when no source names one, so the token lines keep saying
+// `Unknown token` for a token nothing knows.
+function tokenLabel(address, chainId) {
+    return resolveTokenSymbol(address, tokenSourcesByChainId(chainId));
 }
 
 // A network fee in wei as the confirmation and approval screens both show it:
@@ -608,18 +626,28 @@ const EXT_ICON =
     `<path d="M7 1.5h3.5V5M7 5.5L10.5 1.5"/>` +
     `</svg></span>`;
 
-// The node of the network a transaction was reviewed for, the one its chain id
-// names, which need not be the active one: the popup can reopen onto ConfirmTx
-// or WaitTx after Settings switched the network. Its RPC URL is the one
-// Settings has for that network: the active network's is state.rpcUrl, any
-// other's the one remembered for it (see applyChainSwitchFields()).
-function reviewedNetworkProvider(txInfo) {
-    const net = networkByChainId(txInfo.chainId);
+// The RPC and Blockscout URLs Settings has for the network with this chain id,
+// which need not be the active one: ConfirmTx, WaitTx and TransactionDetail
+// use the network their transaction's chain id names, and the popup can reopen
+// onto them after Settings switched the network. The active network's are
+// state.rpcUrl and state.blockscoutUrl, any other's the ones remembered for it,
+// or its defaults (see applyChainSwitchFields()).
+function endpointsByChainId(chainId) {
+    const net = networkByChainId(chainId);
     if (net.id === state.networkId) {
-        return getProvider(state.rpcUrl, net.id);
+        return { rpcUrl: state.rpcUrl, blockscoutUrl: state.blockscoutUrl };
     }
     const remembered = state.networkEndpoints[net.id] || {};
-    return getProvider(remembered.rpcUrl || net.defaultRpcUrl, net.id);
+    return {
+        rpcUrl: remembered.rpcUrl || net.defaultRpcUrl,
+        blockscoutUrl: remembered.blockscoutUrl || net.defaultBlockscoutUrl,
+    };
+}
+
+// The node of the network a transaction was reviewed for.
+function reviewedNetworkProvider(txInfo) {
+    const net = networkByChainId(txInfo.chainId);
+    return getProvider(endpointsByChainId(txInfo.chainId).rpcUrl, net.id);
 }
 
 // Block-explorer URLs. The origin is a per-network constant from
@@ -762,6 +790,7 @@ module.exports = {
     keyMaterialName,
     unknownableAmount,
     nativeCurrency,
+    tokenSourcesByChainId,
     tokenLabel,
     formatFee,
     addressDotHtml,
@@ -777,6 +806,7 @@ module.exports = {
     attachCopyHandlers,
     etherscanLinkHtml,
     explorerUrl,
+    endpointsByChainId,
     reviewedNetworkProvider,
     EXT_ICON,
     truncateMiddle,

src/popup/views/stateRecovery.js

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

src/popup/views/transactionDetail.js

@@ -18,10 +18,11 @@ const {
     copyableHtml,
     etherscanLinkHtml,
     explorerUrl,
+    endpointsByChainId,
     displaySymbol,
     goBack,
 } = require("./helpers");
-const { state, currentNetwork } = require("../../shared/state");
+const { state } = require("../../shared/state");
 const { nativeCurrencyByChainId } = require("../../shared/networks");
 const { formatEther, formatUnits } = require("ethers");
 const { log, debugFetch } = require("../../shared/log");
@@ -84,9 +85,10 @@ function show(tx) {
             contractAddress: tx.contractAddress || null,
             // The network the history entry was read from. The type line and
             // the fee are in its native currency, not the active network's,
-            // and the links open its explorer: the active network can change,
-            // in Settings or when the user approves a site's request, before
-            // a later popup shows this screen again.
+            // the links open its explorer, and the block, network details and
+            // calldata are read from its Blockscout: the active network can
+            // change, in Settings or when the user approves a site's request,
+            // before a later popup shows this screen again.
             chainId: tx.chainId,
         },
     };
@@ -311,8 +313,9 @@ async function loadFullTxDetails(txHash, chainId) {
     if (!section || !actionEl || !detailsEl) return;
 
     try {
+        const { blockscoutUrl } = endpointsByChainId(chainId);
         const resp = await debugFetch(
-            state.blockscoutUrl + "/transactions/" + txHash,
+            blockscoutUrl + "/transactions/" + txHash,
         );
         if (!resp.ok) return;
         const txData = await resp.json();
@@ -326,12 +329,12 @@ async function loadFullTxDetails(txHash, chainId) {
         // Decoded against the address the transaction was sent to, as the
         // explorer reports it, not the history entry's `to`: for a token
         // transfer that is the transfer's recipient, not the token contract.
-        // On the active network, the one whose explorer was just asked, and
-        // from the sender it reports.
+        // On the network the transaction was sent on, whose Blockscout was
+        // just asked, and from the sender it reports.
         const decoded = decodeCalldata(
             inputData,
             txData.to?.hash || "",
-            currentNetwork().chainId,
+            chainId,
             txData.from?.hash || "",
         );
         if (decoded) {

src/popup/views/txStatus.js

@@ -280,7 +280,7 @@ function decodedDetailsHtml(decoded, chainId) {
         html += `<div class="text-xs text-muted mb-1">${escapeHtml(d.label)}</div>`;
         if (d.address) {
             if (d.isToken) {
-                const sym = tokenLabel(d.address) || "Unknown token";
+                const sym = tokenLabel(d.address, chainId) || "Unknown token";
                 html += `<div class="font-bold">${escapeHtml(sym)}</div>`;
                 html += toAddressHtml(d.address, chainId);
             } else {

src/shared/browserApi.js

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

src/shared/prices.js

@@ -38,11 +38,12 @@ function clearPrices() {
 }
 
 // Return the USD price for a symbol on the network with `chainId`, or on the
-// active network when no chain id is given; null on testnet / unknown.
+// active network when no chain id is given; null on testnet, on a chain id
+// that names no network, or for a symbol with no price.
 function getPrice(symbol, chainId) {
     const { currentNetwork } = require("./state");
     const network = chainId ? networkByChainId(chainId) : currentNetwork();
-    if (network.isTestnet) return null;
+    if (!network || network.isTestnet) return null;
     return prices[symbol] || null;
 }
 

src/shared/state.js

@@ -35,7 +35,7 @@ const {
     migrationNeeded,
 } = require("./stateSchema");
 
-const { storageGet, storageSet } = require("./browserApi");
+const { storageGet, storageSet, withLock } = require("./browserApi");
 const { log } = require("./log");
 
 // The live record the proxy below guards. Everything inside this module reads
@@ -458,8 +458,8 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 // This page's own live `state` is deliberately NOT rehydrated from a field
 // another page changed — only the record written to storage is merged.
 // showView() fires saveState() on every navigation without awaiting it,
-// which is what makes the queue above necessary in the first place, and a
-// save that is slow to come back has no way to tell whether the field it
+// which is why saves from one page wait for each other (see saveState()), and
+// a save that is slow to come back has no way to tell whether the field it
 // is about to hand back is still the current answer or has since been
 // overtaken by something this very page did in the meantime; writing it
 // into `state` regardless reintroduced exactly the clobber this function
@@ -467,11 +467,7 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 // (caught by tests/txStatus.test.js). A page's live picture of a field it
 // does not own goes on being whatever its last loadState() saw, same as
 // before this fix; only the persisted record is guaranteed current.
-async function saveStateOnce() {
-    // A copy, so what this save compares and writes is the page's state as it
-    // stood when the save began. A change made while it waits on storage is
-    // left for the next save, which compares against this copy.
-    const current = structuredClone(snapshotPersisted());
+async function saveStateOnce(beforeWrite) {
     const result = await storageGet("autistmask");
     // The record in storage right now is about to be merged into and written
     // back, so it is validated exactly like a load validates it. Without this,
@@ -485,6 +481,12 @@ async function saveStateOnce() {
     // come from storage in its loaded (self-healed) shape. See
     // normalizePersisted() in persistedState.js.
     const fresh = normalizePersisted(result.autistmask);
+    if (beforeWrite && beforeWrite(fresh) === false) return;
+
+    // A copy, so what this save compares and writes is the page's state as it
+    // stood once the stored record was read. A change made while it waits on
+    // the write is left for the next save, which compares against this copy.
+    const current = structuredClone(snapshotPersisted());
 
     const merged = { ...fresh };
     for (const key of PERSISTED_FIELDS) {
@@ -529,35 +531,21 @@ async function saveStateOnce() {
     rawState.hasWallet = rawState.wallets.length > 0;
 
     // What this save compared and wrote, not the page's state now: a change
-    // made during the save must still differ from the baseline, or the save
-    // queued after it finds nothing to store
+    // made during the save must still differ from the baseline, or the next
+    // save finds nothing to store
     // (https://git.eeqj.de/sneak/AutistMask/issues/448).
     baseline = current;
 }
 
-// showView() calls saveState() on every navigation without awaiting it, so
-// two saves from the SAME page can be in flight at once — e.g. a screen
-// shown, then immediately replaced before the first save's storageGet()
-// round trip has come back. Left concurrent, the first save's turn would
-// finish after the second's live-state mutation and then re-hydrate `state`
-// from what IT read, stomping the second, later change back to a stale
-// value — the same clobber this function exists to prevent, just between
-// two saves on one page instead of two pages. Queuing makes every save's
-// snapshot-diff-write-rehydrate run start to finish before the next one
-// begins, so each one only ever sees the true live state at its turn.
-let saveQueue = Promise.resolve();
-
 // Where a failed save is REPORTED, set once by the context that has a screen
 // to say it on (src/popup/index.js).
 //
 // A save that fails must not fail silently. showView() fires saveState() on
-// every navigation without awaiting it, and the queue below has to attach a
-// rejection handler to keep advancing — so a failing save was swallowed
-// entirely: no throw, no message, nothing on screen. The wallet kept running
-// against storage that was rejecting every write, which is the data-loss half
-// of https://git.eeqj.de/sneak/AutistMask/issues/362. The awaited callers were
-// no better off: `await saveState()` inside an unguarded event handler surfaces
-// in the console and nowhere the user looks.
+// every navigation without awaiting it, and `await saveState()` inside an
+// unguarded event handler is no better: either way, without this, a failure
+// would reach only the console, where the user never looks, and the wallet
+// would keep running against storage that rejects every write. That is the
+// data-loss half of https://git.eeqj.de/sneak/AutistMask/issues/362.
 //
 // This is the "tell the user" half; the other half is the floor in
 // normalizePersisted(), which stops the malformed-record cause from arising in
@@ -583,11 +571,25 @@ function reportSaveFailure(err) {
     }
 }
 
-function saveState() {
-    const turn = saveQueue.then(saveStateOnce);
-    // The queue must advance even when a save rejects, or every save after
-    // it queues behind a promise that never settles.
-    saveQueue = turn.catch(() => {});
+// Each save runs start to finish holding the lock every write of the stored
+// record takes (withLock() in src/shared/browserApi.js), so no write by
+// another page or the background lands between its read and its write and is
+// lost (https://git.eeqj.de/sneak/AutistMask/issues/641). A page in a Firefox
+// private window is the exception: Firefox gives it locks of its own (README,
+// "Stored state and its version").
+//
+// The same lock orders this page's own saves. showView() calls saveState() on
+// every navigation without awaiting it, so two saves from one page can be
+// asked for at once; they take the lock in the order they were asked, and each
+// compares the page's state, as it stands once the stored record has been read
+// and `beforeWrite` has run, against the baseline the save before it left.
+//
+// `beforeWrite`, when given, is called inside the lock with the stored record
+// as just read, before this page's state is compared against it. It may change
+// `state`, and this save writes that change. When it returns false, nothing is
+// written; any other return lets the save go ahead.
+function saveState(beforeWrite) {
+    const turn = withLock("autistmask", () => saveStateOnce(beforeWrite));
     // Every failed save is reported, whether or not the caller awaited this
     // one. The returned promise still rejects, so a caller that DOES await
     // keeps its own error handling.

src/shared/transactions.js

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

src/shared/uniswap.js

@@ -494,8 +494,9 @@ function amountText(raw, info) {
     };
 }
 
-// The line giving a moved token under `label`, in the shape of the Token In
-// line, so the screens show it as they show that one. ETH has no address.
+// The line giving a moved token, or the token of a permit, under `label`, in
+// the shape of the Token In line, so the screens show it as they show that
+// one. ETH has no address.
 function tokenMovedLine(label, token, sources) {
     const info = tokenInfo(token, sources);
     if (!present(info.address)) {
@@ -592,13 +593,19 @@ function decodeV2SwapExactOut(input) {
     }
 }
 
-// Decode V3 swap path (packed: token(20) + fee(3) + token(20) ...)
+// The first and last token of a V3 swap path (packed: token(20) + fee(3) +
+// token(20) ...), or null when it is not one token followed by whole hops of
+// a fee and a token (40 hex digits, then 46 per hop). The router reads only
+// whole hops and ignores any bytes after the last one, so the last 20 bytes
+// of such a path are not the token it reads there. Both are checksummed, as
+// the ABI decoder gives every other address, so a token reads the same on
+// every line.
 function decodeV3Path(pathHex) {
     const hex = pathHex.startsWith("0x") ? pathHex.slice(2) : pathHex;
-    if (hex.length < 40) return null;
-    const tokenIn = "0x" + hex.slice(0, 40);
-    const tokenOut = "0x" + hex.slice(-40);
-    return { tokenIn, tokenOut };
+    if (hex.length < 40 || (hex.length - 40) % 46 !== 0) return null;
+    const first = getAddress("0x" + hex.slice(0, 40));
+    const last = getAddress("0x" + hex.slice(-40));
+    return { first, last };
 }
 
 // Decode V3_SWAP_EXACT_IN (command 0x00) input bytes.
@@ -617,8 +624,39 @@ function decodeV3SwapExactIn(input) {
             recipient: d[0],
             amountIn: d[1],
             amountOutMin: d[2],
-            tokenIn: path.tokenIn,
-            tokenOut: path.tokenOut,
+            tokenIn: path.first,
+            tokenOut: path.last,
+            payerIsUser: d[4],
+        };
+    } catch {
+        return null;
+    }
+}
+
+// Decode V3_SWAP_EXACT_OUT (command 0x01) input bytes.
+// ABI: (address recipient, uint256 amountOut, uint256 amountInMax,
+//        bytes path, bool payerIsUser)
+// The router reads an exact-out path from the token it buys to the token it
+// spends: it buys `amountOut` of the path's first token from the path's first
+// pool and pays at most `amountInMax` of its last token to its last pool
+// (`v3SwapExactOutput()` and `uniswapV3SwapCallback()` in each release's
+// `contracts/modules/uniswap/v3/V3SwapRouter.sol`, at the commit linked for
+// it above).
+// With `payerIsUser` false the router pays the input from its own balance.
+function decodeV3SwapExactOut(input) {
+    try {
+        const d = coder.decode(
+            ["address", "uint256", "uint256", "bytes", "bool"],
+            input,
+        );
+        const path = decodeV3Path(d[3]);
+        if (!path) return null;
+        return {
+            recipient: d[0],
+            amountOut: d[1],
+            amountInMax: d[2],
+            tokenIn: path.last,
+            tokenOut: path.first,
             payerIsUser: d[4],
         };
     } catch {
@@ -903,7 +941,10 @@ function totalAmount(amounts) {
 // input side from it only when no earlier step set it. A side it sets that
 // these rules leave unknown is set unknown, with no figure. A step with no
 // swap action sets only the sides SETTLE, SETTLE_ALL, TAKE and TAKE_ALL
-// name.
+// name. Under each of the three rules, rule 3 included, when the user pays
+// the step any of Token In (`paidByUser` below), decode() takes what the user
+// pays it of Token In as the step's amount in place of the rules' Amount, or
+// no amount when this decoder cannot tell what that is.
 //
 // `takes` is every TAKE, TAKE_ALL and TAKE_PORTION, as the currency it takes
 // and its recipient as written, MSG_SENDER for a TAKE_ALL. TAKE_PORTION takes
@@ -1166,14 +1207,52 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         let inputToken = null;
         let inputAmount = null;
         let inputEstablished = false;
-        // The last PERMIT2_PERMIT this decoder read, or null (see
-        // permitStands after the loop).
+        // Whether the user pays the V4 step that set the input side any of
+        // its input currency (see decodeV4Swap()). Only a V4 step can set the
+        // input side with no amount, the one case in which this is read.
+        let inputPaidByUser = false;
+        // The last PERMIT2_PERMIT this decoder read before a step set the
+        // input side, or null (see permitStands after the loop).
         let permit = null;
+        // Every PERMIT2_PERMIT this decoder read, before a step set the input
+        // side or after, in step order, as { token, amount, spender, step }.
+        // Each whose amount is not the Amount figure gets lines of its own
+        // (see after the PERMIT2_TRANSFER_FROM lines).
+        const permits = [];
+        // The index of each step this decoder did not read in full: a
+        // command it does not read, a step whose input it cannot read, in
+        // whole or in part, and one it fails on (see permitStands).
+        const stepsUnread = [];
         let outputToken = null;
         let minOutput = null;
         let outputEstablished = false;
         let hasUnwrapWeth = false;
-        let hasV2ExactOut = false;
+        // Set when an UNWRAP_WETH pays out, as ETH, the output side's WETH,
+        // which the router holds; cleared whenever the output side is set
+        // again, or a later step may pay that ETH out as WETH (see after the
+        // loop). `unwrapIntoRouterStep` is the index of the first such
+        // UNWRAP_WETH that may have paid the ETH to the router, which then
+        // holds it: its recipient is the router or cannot be read. A later
+        // UNWRAP_WETH does not replace it. It is null when there is none, and
+        // is cleared with `outputUnwrapped` when the output side is set again.
+        let outputUnwrapped = false;
+        let unwrapIntoRouterStep = null;
+        // The index of the step that set the output side.
+        let outputStep = -1;
+        // The index of the last step this decoder treats as one that may take
+        // WETH out of the router or pay anyone WETH: any step but one it read
+        // that is a PERMIT2_PERMIT, a BALANCE_CHECK_ERC20, or a SWEEP,
+        // TRANSFER, PAY_PORTION or PAY_PORTION_FULL_PRECISION of a token
+        // other than WETH, and not of ETH to a WETH contract, which pays the
+        // router WETH (see keepsRouterWeth in the loop). None of those can.
+        let lastWethStep = -1;
+        // Where the step that set the output side paid its output: the
+        // recipient of a swap step, as written, or of each TAKE, TAKE_ALL and
+        // TAKE_PORTION of it in a V4 step, a TAKE_ALL as paid to the sender,
+        // with null for a payout of that step this decoder did not read. A
+        // BALANCE_CHECK_ERC20 pays nobody.
+        let outputRecipients = [];
+        let hasV2OrV3ExactOut = false;
         let swapUndecoded = false;
         let hasSubPlan = false;
         const commandNames = [];
@@ -1197,8 +1276,9 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // when no earlier hop set it. A half the establishing hop did not
         // state stays null and the line says so, rather than being filled in
         // from a different hop. A PERMIT2_PERMIT sets no side here: after the
-        // loop, the last one read names Token In, and the Amount line is
-        // formed there, in one place (see permitStands).
+        // loop, one whose amount stands as the Amount figure names Token In,
+        // and the Amount line is formed there, in one place (see
+        // permitStands).
         const setInput = (token, amount) => {
             inputToken = present(token) ? token : null;
             inputAmount = present(amount) ? amount : null;
@@ -1209,16 +1289,21 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             if (!present(token) && !present(amount)) return;
             setInput(token, amount);
         };
-        const setOutput = (token, amount) => {
+        const setOutput = (step, token, amount, recipients) => {
             if (!present(token) && !present(amount)) return;
             outputToken = present(token) ? token : null;
             minOutput = present(amount) ? amount : null;
             outputEstablished = true;
+            outputUnwrapped = false;
+            unwrapIntoRouterStep = null;
+            outputRecipients = recipients;
+            outputStep = step;
         };
 
-        // What each step but the one that sets the input side takes from the
-        // sender, as { token, amount }, in step order. After the loop each
-        // joins the Amount line or gets lines of its own (see permitStands).
+        // 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).
         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
@@ -1227,12 +1312,13 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             if (amount !== ALREADY_PAID) userPaid.push({ token, amount });
         };
         // A step may take from the sender what this decoder did not read: a
-        // V4 step, other than the one that sets the input side, whose input
-        // or one of whose SETTLEs or SETTLE_ALLs it cannot read; a V2 or V3
-        // swap step or PERMIT2_TRANSFER_FROM whose input it cannot read; or a
-        // PERMIT2_TRANSFER_FROM_BATCH. It is recorded with a null token and
-        // amount: one line says so, and there is no Amount line, whose figure
-        // may then be too low.
+        // V4 step whose input or one of whose SETTLEs or SETTLE_ALLs it
+        // cannot read; a V2 or V3 swap step or PERMIT2_TRANSFER_FROM whose
+        // input it cannot read; a PERMIT2_TRANSFER_FROM_BATCH; an
+        // EXECUTE_SUB_PLAN; and a step it fails on. It is recorded with a null
+        // token and amount: one line says so, there is no Amount line, whose
+        // figure may then be too low, and the amount of a permit after it
+        // does not stand (see permitStands).
         const spentUnread = () => {
             userPaid.push({ token: null, amount: null });
         };
@@ -1345,6 +1431,14 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     v2PairFor(chainId, next.path[0], next.path[1]).toLowerCase()
             );
         };
+        // Whether a SWEEP, TRANSFER, PAY_PORTION or PAY_PORTION_FULL_PRECISION
+        // of `token` to `recipient` pays anyone WETH (see lastWethStep): it
+        // does when `token` is WETH, and when it pays ETH to a WETH contract,
+        // which pays the router WETH for it.
+        const paysWeth = (token, recipient) =>
+            WETH_ADDRESSES.includes(token.toLowerCase()) ||
+            (token === "0x0000000000000000000000000000000000000000" &&
+                WETH_ADDRESSES.includes(recipient.toLowerCase()));
 
         for (let i = 0; i < commandsBytes.length; i++) {
             const cmdId = commandsBytes[i] & commandTypeMask;
@@ -1361,28 +1455,46 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     ? COMMAND_NAMES[command]
                     : "Command 0x" + cmdId.toString(16).padStart(2, "0"),
             );
+            // Set by a branch below that reads a step that cannot take WETH
+            // out of the router or pay anyone WETH (see lastWethStep).
+            let keepsRouterWeth = false;
 
             try {
                 if (command === "EXECUTE_SUB_PLAN") {
                     // EXECUTE_SUB_PLAN runs a further list of commands held in
                     // its input, which this decoder does not read. The step
                     // says so, and after this loop neither side is named.
-                    // Those commands may pay any address.
+                    // Those commands may pay any address and take from the
+                    // sender.
                     hasSubPlan = true;
                     commandNames[i] += " (its steps are not shown)";
                     payeeUnread = true;
+                    stepsUnread.push(i);
+                    spentUnread();
                 } else if (command === "PERMIT2_PERMIT") {
                     const p = decodePermit2(inputs[i]);
                     if (p) {
+                        permits.push({ ...p, step: i });
+                        keepsRouterWeth = true;
+                    } else {
+                        stepsUnread.push(i);
+                    }
+                    // Only a permit whose amount stands as the Amount figure
+                    // names Token In (see permitStands). Every other permit,
+                    // before the step that sets the input side or after it,
+                    // leaves Token In and Amount as they read with no permit
+                    // and gets lines of its own. One after a step set the input
+                    // side never stands, so only one before it is kept here.
+                    if (p && !inputEstablished) {
                         // Whether a step before it took its token, or may
-                        // have: the step that set the input side or one in
-                        // `userPaid`, when its token is the permit's or not
-                        // known.
+                        // have: one in `userPaid`, when its token is the
+                        // permit's or not known. No step has set the input
+                        // side yet.
                         const mayBeItsToken = (token) =>
                             !present(token) || sameAddress(token, p.token);
-                        const tookBefore =
-                            (inputEstablished && mayBeItsToken(inputToken)) ||
-                            userPaid.some((t) => mayBeItsToken(t.token));
+                        const tookBefore = userPaid.some((t) =>
+                            mayBeItsToken(t.token),
+                        );
                         permit = {
                             ...p,
                             step: i,
@@ -1394,6 +1506,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     const p = decodePermit2TransferFrom(inputs[i]);
                     if (!p) {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                         spentUnread();
                     } else if (
                         commandTypeMask === 0x1f &&
@@ -1432,6 +1545,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         // owner may be any address. It sets no side, and the
                         // step says so.
                         commandNames[i] += " (could not be decoded)";
+                        stepsUnread.push(i);
                     } else if (b.owner.toLowerCase() !== sender) {
                         // The router reads the owner as written (see
                         // decodeBalanceCheck()), so address(1) and address(2)
@@ -1440,6 +1554,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         // what the user receives: it sets no side, and the
                         // step says so.
                         commandNames[i] += " (of another address)";
+                        keepsRouterWeth = true;
                     } else {
                         // The router passes this check whenever the owner
                         // holds at least minBalance, so a zero one guarantees
@@ -1450,8 +1565,9 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         // does. It pays nobody.
                         const minBalance = allowedToFail ? 0n : b.minBalance;
                         if (!(minBalance === 0n && present(minOutput))) {
-                            setOutput(b.token, minBalance);
+                            setOutput(i, b.token, minBalance, []);
                         }
+                        keepsRouterWeth = true;
                     }
                 } else if (command === "V3_SWAP_EXACT_IN") {
                     const s = decodeV3SwapExactIn(inputs[i]);
@@ -1464,7 +1580,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         // Always update output: in multi-step swaps (V3 → V4),
                         // the last swap step determines the final output token
                         // and minimum received amount.
-                        setOutput(s.tokenOut, s.amountOutMin);
+                        setOutput(i, s.tokenOut, s.amountOutMin, [s.recipient]);
                         if (!s.payerIsUser) {
                             spendFromRouter(s.tokenIn, s.amountIn);
                         }
@@ -1473,6 +1589,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                         spentUnread();
                     }
                 } else if (command === "V2_SWAP_EXACT_IN") {
@@ -1483,7 +1600,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         } else if (s.payerIsUser) {
                             addUserPaid(s.tokenIn, s.amountIn);
                         }
-                        setOutput(s.tokenOut, s.amountOutMin);
+                        setOutput(i, s.tokenOut, s.amountOutMin, [s.recipient]);
                         if (!s.payerIsUser) {
                             spendFromRouter(s.tokenIn, s.amountIn);
                         }
@@ -1492,30 +1609,42 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                         spentUnread();
                     }
-                } else if (command === "V2_SWAP_EXACT_OUT") {
+                } else if (
+                    command === "V2_SWAP_EXACT_OUT" ||
+                    command === "V3_SWAP_EXACT_OUT"
+                ) {
                     // Buys exactly amountOut and spends at most amountInMax.
-                    hasV2ExactOut = true;
-                    const s = decodeV2SwapExactOut(inputs[i]);
+                    // Paid from the router, it spends an amount the calldata
+                    // does not state, so it spends nothing spendFromRouter()
+                    // could count.
+                    hasV2OrV3ExactOut = true;
+                    const s =
+                        command === "V2_SWAP_EXACT_OUT"
+                            ? decodeV2SwapExactOut(inputs[i])
+                            : decodeV3SwapExactOut(inputs[i]);
                     if (s) {
                         if (!inputEstablished) {
                             setInputOnce(s.tokenIn, s.amountInMax);
                         } else if (s.payerIsUser) {
                             addUserPaid(s.tokenIn, s.amountInMax);
                         }
-                        setOutput(s.tokenOut, s.amountOut);
+                        setOutput(i, s.tokenOut, s.amountOut, [s.recipient]);
                         if (!isHop(i, s.tokenOut, s.recipient)) {
                             addPayee(s.recipient, s.tokenOut);
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                         spentUnread();
                     }
                 } else if (command === "PERMIT2_TRANSFER_FROM_BATCH") {
                     // It moves the sender's tokens to any addresses, and this
                     // decoder does not read it.
                     payeeUnread = true;
+                    stepsUnread.push(i);
                     spentUnread();
                 } else if (command === "SWEEP") {
                     const s = decodeSweep(inputs[i]);
@@ -1524,8 +1653,10 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         if (!isRouter(s.recipient)) {
                             heldByRouter.delete(s.token.toLowerCase());
                         }
+                        keepsRouterWeth = !paysWeth(s.token, s.recipient);
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                     }
                 } else if (
                     command === "TRANSFER" ||
@@ -1560,8 +1691,10 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         ) {
                             heldByRouter.delete(t.token.toLowerCase());
                         }
+                        keepsRouterWeth = !paysWeth(t.token, t.recipient);
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                     }
                 } else if (command === "ACROSS_V4_DEPOSIT_V3") {
                     const a = decodeAcrossV4DepositV3(inputs[i]);
@@ -1585,6 +1718,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                     }
                 } else if (command === "WRAP_ETH") {
                     const w = decodeWrapEth(inputs[i]);
@@ -1615,6 +1749,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                     }
                 } else if (command === "V4_SWAP") {
                     const v4 = decodeV4Swap(inputs[i]);
@@ -1634,12 +1769,36 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     if (!v4 || v4.recipientUnread) {
                         payeeUnread = true;
                     }
+                    if (
+                        !v4 ||
+                        v4.recipientUnread ||
+                        v4.settleUnread ||
+                        v4.swapUndecoded
+                    ) {
+                        stepsUnread.push(i);
+                    }
                     if (v4 && v4.swapUndecoded) {
                         // A swap action of this step went unread, so the step
                         // is marked.
                         swapUndecoded = true;
                         commandNames[i] += " (could not be decoded)";
                     }
+                    // The step's amount, if it sets the input side: what the
+                    // user pays it of its input currency (see
+                    // decodeV4Swap()), or, when the user pays none of it,
+                    // what its swap actions spend of it, whoever pays that.
+                    const paidIn = v4?.paidByUser.find(
+                        (p) => p.currency === v4.tokenIn,
+                    );
+                    const amountIn = paidIn ? paidIn.amount : v4?.amountIn;
+                    // Where the step pays its output, if it sets the output
+                    // side (see outputRecipients).
+                    const takeRecipients = v4
+                        ? v4.takes
+                              .filter((t) => t.currency === v4.tokenOut)
+                              .map((t) => t.recipient)
+                              .concat(v4.recipientUnread ? [null] : [])
+                        : [];
                     if (v4 && v4.hasSwapAction) {
                         // A step with a swap action always sets the output
                         // side, as the last swap step wins, and sets the
@@ -1651,39 +1810,85 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         // token, likewise never sits beside an earlier step's
                         // other half.
                         if (!inputEstablished) {
-                            setInput(v4.tokenIn, v4.amountIn);
+                            setInput(v4.tokenIn, amountIn);
                         }
                         outputToken = v4.tokenOut;
                         minOutput = v4.amountOutMin;
                         outputEstablished = true;
+                        outputUnwrapped = false;
+                        unwrapIntoRouterStep = null;
+                        outputRecipients = takeRecipients;
+                        outputStep = i;
                     } else if (v4) {
                         // A step with no swap action sets only the sides its
                         // SETTLE, SETTLE_ALL, TAKE or TAKE_ALL names:
                         // setInputOnce() and setOutput() leave alone a side
                         // whose two halves are both unstated.
-                        setInputOnce(v4.tokenIn, v4.amountIn);
-                        setOutput(v4.tokenOut, v4.amountOutMin);
+                        setInputOnce(v4.tokenIn, amountIn);
+                        setOutput(
+                            i,
+                            v4.tokenOut,
+                            v4.amountOutMin,
+                            takeRecipients,
+                        );
                     }
-                    // Every V4 step but the one that sets the input side,
-                    // with a swap action or without, takes from the sender
-                    // what the user pays it (an amount an unread action may
-                    // change is null). One whose input, or one of whose
-                    // SETTLEs or SETTLE_ALLs, this decoder could not read may
-                    // take anything: the router still runs it.
+                    // Every V4 step, with a swap action or without, takes
+                    // from the sender what the user pays it (an amount an
+                    // unread action may change is null), less what the step
+                    // that sets the input side counts as its amount. One
+                    // whose input, or one of whose SETTLEs or SETTLE_ALLs,
+                    // this decoder could not read may take anything: the
+                    // router still runs it.
                     const setInputHere = inputEstablished && !inputSetBefore;
-                    if (!setInputHere) {
-                        if (v4) {
-                            for (const p of v4.paidByUser) {
-                                addUserPaid(p.currency, p.amount);
-                            }
-                        }
-                        if (!v4 || v4.settleUnread) {
-                            spentUnread();
+                    if (setInputHere) inputPaidByUser = paidIn !== undefined;
+                    if (v4) {
+                        for (const p of v4.paidByUser) {
+                            if (setInputHere && p === paidIn) continue;
+                            addUserPaid(p.currency, p.amount);
                         }
                     }
+                    if (!v4 || v4.settleUnread) {
+                        spentUnread();
+                    }
                 } else if (command === "UNWRAP_WETH") {
                     hasUnwrapWeth = true;
+                    // The router unwraps all the WETH it holds, even when the
+                    // recipient cannot be read. The output side's WETH is
+                    // among it when the step that set the output side paid it
+                    // to the router and the router still holds WETH. WETH
+                    // that step paid to the user, or to anyone else, stays
+                    // WETH. When that step also paid some of its output
+                    // elsewhere or made a payout this decoder did not read,
+                    // or this decoder treats a step between the two as one
+                    // that may take WETH out of the router or pay anyone WETH
+                    // (see lastWethStep), the WETH unwrapped may be only part
+                    // of the output side's, or none of it.
+                    // This decoder does not count how much of that step's
+                    // minimum then reaches the UNWRAP_WETH, nor read the
+                    // UNWRAP_WETH's own minimum, so the output side keeps no
+                    // figure.
                     const u = decodeUnwrapWeth(inputs[i]);
+                    const toRouter = (r) => present(r) && isRouter(r);
+                    if (
+                        present(outputToken) &&
+                        WETH_ADDRESSES.includes(outputToken.toLowerCase()) &&
+                        heldByRouter.has(outputToken.toLowerCase()) &&
+                        outputRecipients.some(toRouter)
+                    ) {
+                        outputUnwrapped = true;
+                        if (
+                            unwrapIntoRouterStep === null &&
+                            (u === null || isRouter(u.recipient))
+                        ) {
+                            unwrapIntoRouterStep = i;
+                        }
+                        if (
+                            !outputRecipients.every(toRouter) ||
+                            lastWethStep > outputStep
+                        ) {
+                            minOutput = null;
+                        }
+                    }
                     if (u) {
                         addPayee(u.recipient);
                         // It pays out all the router's WETH, as ETH. Into the
@@ -1701,20 +1906,45 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                     }
                 } else {
                     // Any other step may pay an address this decoder does not
-                    // read: V3_SWAP_EXACT_OUT and the NFT commands among them,
-                    // and a type the release names no command for.
+                    // read: PERMIT2_PERMIT_BATCH and the NFT commands among
+                    // them, and a type the release names no command for.
                     payeeUnread = true;
+                    stepsUnread.push(i);
                 }
             } catch {
-                // Skip commands we can't decode. One may pay any address.
+                // Skip commands we can't decode. One may pay any address and
+                // take from the sender.
                 payeeUnread = true;
+                stepsUnread.push(i);
+                spentUnread();
             }
             if (allowedToFail) {
                 commandNames[i] += " (allowed to fail)";
             }
+            if (!keepsRouterWeth) {
+                lastWethStep = i;
+            }
+        }
+
+        // After an UNWRAP_WETH that may have paid the output side's WETH to
+        // the router as ETH, a later step may pay that ETH out as WETH, as a
+        // WRAP_ETH of it to the user does. This decoder treats every later
+        // step but those lastWethStep names as one that may, and does not
+        // count how much of that ETH each pays out: after one, the output
+        // side reads as WETH with no figure. Neither this nor the loss of the
+        // figure in the UNWRAP_WETH branch is undone by any later step, a
+        // later UNWRAP_WETH included, but one that sets the output side again.
+        if (
+            outputUnwrapped &&
+            unwrapIntoRouterStep !== null &&
+            lastWethStep > unwrapIntoRouterStep
+        ) {
+            outputUnwrapped = false;
+            minOutput = null;
         }
 
         // The Amount line, and the lines for what the steps take beyond it.
@@ -1727,16 +1957,21 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // lines of its own. One whose amount is not known also leaves the
         // total unknown, with no figure.
         //
-        // The last PERMIT2_PERMIT read names Token In. Its amount stands as
-        // the Amount figure in place of the total only in the plain shape of
-        // Uniswap's own routes: it is the only PERMIT2_PERMIT, its spender is
-        // the router, the router may not let it fail, no step before it took
-        // its token or one not known, and no PERMIT2_PERMIT_BATCH comes after
-        // it. Permit2 then
-        // lets the router take no more of the token than that amount, so the
-        // permit covers every take of it. A step this decoder does not read
-        // that may take from the sender leaves no figure in any case, and an
-        // EXECUTE_SUB_PLAN step leaves both sides unknown (below).
+        // 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
+        // plain shape of Uniswap's own routes: it comes before the step that
+        // set the input side, it is the only PERMIT2_PERMIT in the
+        // transaction, its spender is the router, the router may not let it
+        // fail, no step before it took its token or one not known, and this
+        // decoder read every step after it in full (see stepsUnread). Permit2
+        // then lets the router take no more of the token than that amount, so
+        // the permit covers every take of it. A later step this decoder did
+        // not read may raise what Permit2 lets the router take, as a
+        // PERMIT2_PERMIT_BATCH can. Every other PERMIT2_PERMIT leaves Token In
+        // and the Amount line as they read with no permit, and gets lines of
+        // its own below. A step that may take from the sender what this decoder
+        // did not read leaves no figure, permit or not (see spentUnread()),
+        // and an EXECUTE_SUB_PLAN step leaves both sides unknown (below).
         const stepCommands = Array.from(
             commandsBytes,
             (b) => commands[b & commandTypeMask],
@@ -1747,22 +1982,33 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             sameAddress(permit.spender, toAddress) &&
             !permit.allowedToFail &&
             permit.beforeEveryTake &&
-            !stepCommands
-                .slice(permit.step + 1)
-                .includes("PERMIT2_PERMIT_BATCH");
+            !stepsUnread.some((step) => step > permit.step);
         // What the steps take that the Amount line does not give, as
         // { token, amount }. A null token is a step this decoder did not read
         // (see spentUnread()), or a token it does not know.
         const spentFromSender = [];
         let total = null;
-        if (permit === null || sameAddress(inputToken, permit.token)) {
+        // Whether the step that set the input side counts as a take from the
+        // sender, which may get lines of its own. The amount it stated counts
+        // whoever pays it. Stating none, it counts only when the user pays it
+        // some of its input token: paid from the router, it takes nothing
+        // from the sender.
+        const hasFirstTake =
+            inputEstablished && (present(inputAmount) || inputPaidByUser);
+        // The take of the step that set the input side, when the total
+        // starts from it and it stated no amount (see below), or null.
+        let firstTakeUnstated = null;
+        if (!permitStands || sameAddress(inputToken, permit.token)) {
             total = inputAmount;
-        } else if (inputEstablished) {
+            if (hasFirstTake && !present(inputAmount)) {
+                firstTakeUnstated = { token: inputToken, amount: null };
+            }
+        } else if (hasFirstTake) {
             // The step that set the input side spent a token other than the
-            // permit's, or one not known, so the total starts with no figure.
+            // permit's, or one not known, so its amount gets lines of its own.
             spentFromSender.push({ token: inputToken, amount: inputAmount });
         }
-        if (permit !== null) inputToken = permit.token;
+        if (permitStands) inputToken = permit.token;
         for (const t of userPaid) {
             const ofTokenIn = sameAddress(t.token, inputToken);
             if (ofTokenIn && permitStands) continue;
@@ -1778,35 +2024,48 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             if (ofTokenIn && !present(t.amount)) total = null;
         }
         inputAmount = permitStands ? permit.amount : total;
+        // With no Amount figure, a later take's own figure, or that of a
+        // PERMIT2_TRANSFER_FROM of the same token, into the router or not,
+        // could read as all that leaves, so the step that set the input side,
+        // when the user pays it and it stated no amount, then gets lines of
+        // its own too, first, saying its amount is not known.
+        if (
+            !present(inputAmount) &&
+            firstTakeUnstated !== null &&
+            (spentFromSender.some((s) => present(s.amount)) ||
+                [...movedFromSender, ...movedIntoRouter].some((m) =>
+                    sameAddress(m.token, firstTakeUnstated.token),
+                ))
+        ) {
+            spentFromSender.unshift(firstTakeUnstated);
+        }
 
         // The commands of an EXECUTE_SUB_PLAN step may spend the user's tokens
-        // or pay the user, before or after any other step, and a permit among
-        // them would name Token In. What the other steps state is
-        // then not the whole swap, so both sides are set unknown, with no
-        // figure, wherever the step stands.
+        // or pay the user, before or after any other step. What the other
+        // steps state is then not the whole swap, so both sides are set
+        // unknown, with no figure, wherever the step stands.
         if (hasSubPlan) {
             inputToken = null;
             inputAmount = null;
             outputToken = null;
             minOutput = null;
             outputEstablished = true;
+            outputUnwrapped = false;
         }
 
         // Resolve token info. A null token on either side means no step named
         // a currency for it, a V4 step with a swap action left it unknown, or
         // an EXECUTE_SUB_PLAN step did; tokenInfo() refuses rather than calling
         // it ETH. UNWRAP_WETH turns WETH into ETH, so it makes the output ETH
-        // when the output side is WETH, or when no step set the output side. A
-        // V4 step with a swap action, or an EXECUTE_SUB_PLAN step, did set it,
-        // even when it set it unknown. Any other output keeps its own token
-        // and figure: a swap that buys USDC and then unwraps the WETH it did
-        // not spend receives USDC.
-        const outputIsWeth =
-            present(outputToken) &&
-            WETH_ADDRESSES.includes(outputToken.toLowerCase());
+        // when it unwraps the output side's WETH (`outputUnwrapped`), or when
+        // no step set the output side. A V4 step with a swap action, or
+        // an EXECUTE_SUB_PLAN step, did set it, even when it set it unknown.
+        // Any other output keeps its own token and figure: a swap that pays
+        // its WETH to the user and then unwraps receives WETH, and one that
+        // buys USDC and then unwraps the WETH it did not spend receives USDC.
         const inInfo = tokenInfo(inputToken, sources);
         const outInfo =
-            hasUnwrapWeth && (outputIsWeth || !outputEstablished)
+            outputUnwrapped || (hasUnwrapWeth && !outputEstablished)
                 ? { symbol: "ETH", decimals: 18, address: null }
                 : tokenInfo(outputToken, sources);
 
@@ -1872,12 +2131,12 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             if (amount >= MAX_UINT160) {
                 return { raw: "Unlimited", display: "Unlimited" };
             }
-            if (hasV2ExactOut) {
-                // A V2 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 is said to
-                // be a maximum, in `raw` too: the wait, success and error
-                // screens show `raw` as the transaction's amount.
+            if (hasV2OrV3ExactOut) {
+                // 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
+                // is said to be a maximum, in `raw` too: the wait, success and
+                // error screens show `raw` as the transaction's amount.
                 const most = amountText(amount, info);
                 return {
                     raw: "Up to " + most.raw,
@@ -1942,6 +2201,32 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             );
         }
 
+        // What each PERMIT2_PERMIT lets its spender take: its amount, its
+        // token and the spender, an address on a line of its own. Permit2's
+        // maximum is unbounded. Only a permit whose amount stands as the
+        // Amount figure (see permitStands) gets none: that line already gives
+        // its amount and Token In its token, and its spender is the router.
+        // Every other permit, one after the step that set the input side
+        // included, gets these lines, so nothing it lets anyone take goes
+        // unstated.
+        for (const p of permits) {
+            if (permitStands && p.step === permit.step) continue;
+            details.push({
+                label: "Permit2 allowance",
+                value:
+                    p.amount >= MAX_UINT160
+                        ? "Unlimited"
+                        : amountText(p.amount, tokenInfo(p.token, sources))
+                              .display,
+            });
+            details.push(tokenMovedLine("Allowance token", p.token, sources));
+            details.push({
+                label: "Allowance spender",
+                value: p.spender,
+                address: p.spender,
+            });
+        }
+
         // Keyed on the address, not the symbol: a token absent from the
         // bundled list has no symbol, and gating the line on one dropped it
         // entirely, leaving a Min. received figure with nothing saying what is
@@ -2071,4 +2356,4 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
     }
 }
 
-module.exports = { decode };
+module.exports = { decode, routerRelease };

tests/approvalTokenNetwork.test.js

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

tests/approvalValueUsd.test.js

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

tests/backNavigation.test.js

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

tests/backgroundStateIsolation.test.js

@@ -19,7 +19,10 @@
 //     that followed persisted the pre-refresh values — while still stamping
 //     lastBalanceRefresh, suppressing the redo.
 //
-// Both use the real persistence path over a cloning storage stub. Nothing here
+// A network switch landing inside a balance refresh's round trip is covered at
+// the end (https://git.eeqj.de/sneak/AutistMask/issues/577).
+//
+// All use the real persistence path over a cloning storage stub. Nothing here
 // asserts the absence of a loadState() call; each asserts the OUTCOME, so it
 // holds against any implementation that gets the outcome right.
 
@@ -395,3 +398,48 @@ describe("a balance refresh under another handler's state read", () => {
         expect(after.wallets[0].addresses[0].balance).toBe(REFRESHED_BALANCE);
     });
 });
+
+describe("a balance refresh under a network switch", () => {
+    // https://git.eeqj.de/sneak/AutistMask/issues/577. The switch clears every
+    // address's balances, and a refresh that started on the previous network
+    // must not write that network's back over them when it returns. The same
+    // refresh in the popup is in tests/balanceRefreshNetworkSwitch.test.js.
+    test("a refresh that returns after a switch writes nothing, and the next one runs on the new network", async () => {
+        const roundTrip = deferred();
+        const reachedNetwork = deferred();
+        const ranOn = [];
+
+        const bg = loadWorker("sepolia", {
+            refreshBalances: async (wallets, rpcUrl, explorer, tokens, id) => {
+                ranOn.push(id);
+                reachedNetwork.resolve();
+                await roundTrip.promise;
+                wallets[0].addresses[0].balance = REFRESHED_BALANCE;
+            },
+        });
+
+        const refresh = bg.fireBalanceAlarm();
+        await reachedNetwork.promise;
+
+        // The user switches to Ethereum Mainnet in Settings while the round
+        // trip is out.
+        const during = bg.persisted();
+        applyChainSwitchFields(during, MAINNET.id);
+        global.chrome.storage.write("autistmask", during);
+
+        roundTrip.resolve();
+        await refresh;
+
+        const after = bg.persisted();
+        expect(after.networkId).toBe("mainnet");
+        expect(after.wallets[0].addresses[0].balance).toBe("0");
+        expect(after.lastBalanceRefresh).toBe(0);
+
+        await bg.fireBalanceAlarm();
+
+        expect(ranOn).toEqual(["sepolia", "mainnet"]);
+        expect(bg.persisted().wallets[0].addresses[0].balance).toBe(
+            REFRESHED_BALANCE,
+        );
+    });
+});

tests/balanceRefreshNetworkSwitch.test.js

@@ -0,0 +1,160 @@
+// A balance refresh the popup started on one network, and that returns after
+// the network was switched to another, writes nothing: the switch cleared every
+// address's balances, and the previous network's must not come back over them
+// (https://git.eeqj.de/sneak/AutistMask/issues/577). The switch is made either
+// by the user in this popup's Settings, or by the background after the user
+// 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.
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+    TOKEN_ADDRESS,
+} = require("./support/popupBoot");
+const { applyChainSwitchFields } = require("../src/shared/chainSwitchFields");
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+// Starts the ten-second refresh and holds it open. The balance stand-in writes
+// Ethereum Mainnet's balances in place, on the records handed in, as the real
+// refreshBalances() does, once the returned function is called. Resolves with
+// that function and the refresh still running.
+async function holdRefresh(page) {
+    const { refreshBalances } = require("../src/shared/balances");
+    let answer;
+    refreshBalances.mockImplementationOnce(async (wallets) => {
+        await new Promise((resolve) => {
+            answer = resolve;
+        });
+        wallets[0].addresses[0].balance = "7.0";
+        wallets[0].addresses[0].tokenBalances = [
+            {
+                address: TOKEN_ADDRESS,
+                name: "Test Token",
+                symbol: "TST",
+                decimals: 18,
+                balance: "5.0",
+                holders: null,
+            },
+        ];
+    });
+    const ticking = page.tick();
+    await page.settle();
+    return {
+        finish: async () => {
+            answer();
+            await ticking;
+        },
+    };
+}
+
+// Picks `networkId` in the Settings network selector, as the user does.
+async function chooseNetwork(page, networkId) {
+    const select = page.node("settings-network");
+    select.value = networkId;
+    for (const fn of select.listeners.change) await fn();
+    await page.settle();
+}
+
+// The stored record holds none of Ethereum Mainnet's balances, and no refresh
+// recorded as done.
+function expectNothingStored(page) {
+    const stored = page.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.wallets[0].addresses[0].balance).toBe("0");
+    expect(stored.wallets[0].addresses[0].tokenBalances).toEqual([]);
+    expect(stored.lastBalanceRefresh).toBe(0);
+}
+
+test("a refresh that returns after a switch in Settings writes nothing, and the next one runs on the new network", async () => {
+    const page = await bootPopup(unversionedValidProfile());
+    expect(page.pageErrors).toEqual([]);
+    const { refreshBalances } = require("../src/shared/balances");
+    const { state } = require("../src/shared/state");
+
+    const refresh = await holdRefresh(page);
+    await page.click("btn-settings");
+    await chooseNetwork(page, "sepolia");
+    await refresh.finish();
+
+    expect(state.wallets[0].addresses[0].balance).toBe("0");
+    expect(state.wallets[0].addresses[0].tokenBalances).toEqual([]);
+    expectNothingStored(page);
+
+    await page.click("btn-settings-back");
+    expect(page.visibleViews()).toEqual(["main"]);
+    expect(page.text("total-value")).toBe("0.0000 SepoliaETH");
+
+    await page.tick();
+
+    expect(refreshBalances.mock.lastCall[4]).toBe("sepolia");
+    expect(page.storage.read("autistmask").lastBalanceRefresh).toBeGreaterThan(
+        0,
+    );
+});
+
+// The stored record still holds Ethereum Mainnet while the refresh's save reads
+// it, so only this page's own network shows the switch.
+test("a refresh whose save is reading the stored record when the user switches in Settings writes nothing", async () => {
+    const page = await bootPopup(unversionedValidProfile());
+    expect(page.pageErrors).toEqual([]);
+    const { state } = require("../src/shared/state");
+
+    const refresh = await holdRefresh(page);
+    await page.click("btn-settings");
+
+    // The next read of the stored record, the refresh's save's, is held.
+    const get = page.storage.local.get;
+    const read = get.getMockImplementation();
+    let releaseRead;
+    get.mockImplementationOnce(async (key) => {
+        await new Promise((resolve) => {
+            releaseRead = resolve;
+        });
+        return read(key);
+    });
+    const finishing = refresh.finish();
+    await page.settle();
+
+    // The user picks Sepolia meanwhile; the switch's own save waits for the
+    // refresh's save to let the lock go.
+    const select = page.node("settings-network");
+    select.value = "sepolia";
+    const switching = Promise.all(select.listeners.change.map((fn) => fn()));
+    await page.settle();
+
+    releaseRead();
+    await finishing;
+    await switching;
+    await page.settle();
+
+    expect(state.networkId).toBe("sepolia");
+    expect(state.wallets[0].addresses[0].balance).toBe("0");
+    expect(state.wallets[0].addresses[0].tokenBalances).toEqual([]);
+    expectNothingStored(page);
+});
+
+test("a refresh that returns after the background switched the network writes nothing", async () => {
+    const page = await bootPopup(unversionedValidProfile());
+    expect(page.pageErrors).toEqual([]);
+    const { saveState } = require("../src/shared/state");
+
+    const refresh = await holdRefresh(page);
+    // The background writes the switch to Sepolia, as its updateState() does
+    // once the user approves a site's request. This page is not told.
+    const record = page.storage.read("autistmask");
+    applyChainSwitchFields(record, "sepolia");
+    page.storage.write("autistmask", record);
+    await refresh.finish();
+
+    expectNothingStored(page);
+
+    // Nor does a later save by this page, such as every navigation makes.
+    await saveState();
+
+    expectNothingStored(page);
+});

tests/confirmTxAmount.test.js

@@ -158,7 +158,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const {
     Interface,

tests/confirmTxNetworkSwitch.test.js

@@ -189,7 +189,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const {
     BaseWallet,

tests/dustThreshold.test.js

@@ -101,7 +101,7 @@ describe("the flash line the message is shown in", () => {
     //
     // The line cuts a message too long for it with an ellipsis (see
     // showFlash() in src/popup/views/helpers.js). The assertions that
-    // measure that, in a real browser at the documented 360x600 popup, are
+    // measure that, in a real browser at the documented 396x600 popup, are
     // "a rejected dust threshold shifts no layout (#233)" and "an over-long
     // flash message keeps to one line (#252)" in tests/e2e/run.js, run by
     // make test-e2e. They are not in make check because REPO_POLICIES.md

tests/e2e/run.js

@@ -60,6 +60,14 @@ const TEST_TIMEOUT_MS = 120000;
 // trailing drain in main().
 const TRAILING_WATCH_MS = 1500;
 
+// The popup's size, as README gives it: `body` in src/popup/styles/main.css
+// is 396px wide, and src/background/index.js opens an approval window at
+// the same 396x600. Pages in this context otherwise get Playwright's
+// 1280x720 default, where the page never scrolls sideways and a button
+// below the popup's fold is still on screen, so a layout measured there
+// passes whatever the page does.
+const POPUP_VIEWPORT = { width: 396, height: 600 };
+
 const tests = [];
 
 function test(name, fn) {
@@ -359,11 +367,14 @@ async function leaveTransactionDetail(page) {
     await openAddressDetail(page);
 }
 
-// Back out to Home from wherever the previous test finished.
+// Back out to Home from wherever the previous test finished, and wait for the
+// save that navigation makes, so a test reading the stored stack next reads
+// the one Home left.
 async function goHome(page) {
     await leaveTransactionDetail(page);
     await page.click("#btn-address-back");
     await visible(page, "#view-main");
+    await waitForPersisted(page, "currentView", "main", "back on Home");
 }
 
 // One field of the popup's state as it was actually persisted, read out of
@@ -1885,12 +1896,6 @@ test("a network switch in Settings shows and removes the testnet banner at once
 
 // ------------------------------------------------ dust threshold (#233)
 
-// The popup size README documents the UI as designed for. Pages in this
-// context otherwise get Playwright's 1280x720 default, at which the flash
-// line has room for any plausible message and never wraps — measuring
-// there would pass for every string and prove nothing.
-const POPUP_VIEWPORT = { width: 360, height: 600 };
-
 // Everything below the flash line that must not move when it fills, plus
 // the height of the line itself. Runs in the page.
 //
@@ -2139,7 +2144,7 @@ test("a password error moves nothing on any screen (#297)", async (env) => {
 
 // ------------------------------------------ add wallet Import button (#493)
 
-// At 360x600 the add wallet screen's Import button already starts near the
+// At 396x600 the add wallet screen's Import button already starts near the
 // bottom of the popup, so its password error line sits beside the button
 // rather than above it. Measures the button and the line empty and again
 // filled with the longest error addWallet.js puts there. Runs in the page.
@@ -3431,10 +3436,14 @@ test("six failed receipt lookups in a row end on the unreachable-network message
 // timeout ("<iframe id=\"pwn\"> intercepts pointer events") rather than as
 // anything that names the defect.
 
-// Verbatim from the issue's reproduction.
+// The issue's reproduction, with the frame sized to the popup.
 const HOSTILE_SYMBOL =
     '<iframe id="pwn" src="https://dapp.e2e.test/" ' +
-    'style="position:fixed;left:0;top:0;width:360px;height:600px;z-index:99999"></iframe>';
+    'style="position:fixed;left:0;top:0;width:' +
+    POPUP_VIEWPORT.width +
+    "px;height:" +
+    POPUP_VIEWPORT.height +
+    'px;z-index:99999"></iframe>';
 
 // What a correctly escaped and capped render of it reads as: the first
 // MAX_SYMBOL_LENGTH-1 characters and an ellipsis. Spelled out rather than
@@ -5026,8 +5035,20 @@ function addressRowReport(page) {
     });
 }
 
+// Measured at the popup's 396x600 (POPUP_VIEWPORT). Every page in this
+// context, approval windows included, is otherwise 1280x720 whatever size
+// the extension asks for, and a page that wide never scrolls sideways. The
+// page is then put back to the size it had, so the size a later step runs at
+// does not depend on whether this one ran.
 async function assertAddressesFit(page, where) {
-    const report = await addressRowReport(page);
+    const sizeBefore = page.viewportSize();
+    await page.setViewportSize(POPUP_VIEWPORT);
+    let report;
+    try {
+        report = await addressRowReport(page);
+    } finally {
+        await page.setViewportSize(sizeBefore);
+    }
     assert(
         report.rows.length > 0,
         where + ": no address rows were rendered, so nothing was measured",

tests/nativeCurrency.test.js

@@ -151,7 +151,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const { state } = require("../src/shared/state");
 const { NETWORKS } = require("../src/shared/networks");

tests/persistedEntryFloors.test.js

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

tests/persistedFieldContract.test.js

@@ -465,12 +465,19 @@ const CONTRACT = [
                         from: ADDRESS,
                         to: ADDRESS,
                         contractAddress: 42,
+                        chainId: "0x1",
                     },
                 },
                 views: ["transaction"],
                 restored: false,
             },
-            // A chain id naming no network has no explorer to link to.
+            // A transaction whose chain id is missing or names no network has
+            // no explorer to link to and no Blockscout to be read from.
+            {
+                value: { tx: { hash: "0x1", from: ADDRESS, to: ADDRESS } },
+                views: ["transaction"],
+                restored: false,
+            },
             {
                 value: {
                     tx: {
@@ -836,7 +843,13 @@ const WELL_FORMED_DATA = {
     message: "boom",
     to: ADDRESS,
     decoded: { details: [{ address: TOKEN_ADDRESS }] },
-    tx: { hash: "0x1", from: ADDRESS, to: ADDRESS, contractAddress: null },
+    tx: {
+        hash: "0x1",
+        from: ADDRESS,
+        to: ADDRESS,
+        contractAddress: null,
+        chainId: "0x1",
+    },
     pendingTx: {
         token: "ETH",
         from: ADDRESS,

tests/popupBoot.test.js

@@ -58,7 +58,7 @@ function restoringOnto(view, viewData) {
 test("the transaction screen's Blockscout request reaches the stub", async () => {
     const page = await bootPopup(
         restoringOnto("transaction", {
-            tx: { hash: "0x1", from: ADDRESS, to: ADDRESS },
+            tx: { hash: "0x1", from: ADDRESS, to: ADDRESS, chainId: "0x1" },
         }),
     );
 

tests/sendAmountRule.test.js

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

tests/sendDisplayFloor.test.js

@@ -151,7 +151,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const { refreshBalances } = require("../src/shared/balances");
 const { state } = require("../src/shared/state");

tests/sendMax.test.js

@@ -146,7 +146,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const { Transaction, Wallet, formatEther } = require("ethers");
 const { refreshBalances } = require("../src/shared/balances");

tests/stateMerge.test.js

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

tests/stateWriteLock.test.js

@@ -0,0 +1,96 @@
+// A popup save reads the stored record, merges this page's changes into it
+// and writes it back. The background's write of a network the user approved
+// used to be able to land between that read and that write, and the popup's
+// write then put the old network back
+// (https://git.eeqj.de/sneak/AutistMask/issues/641). Every write of the record
+// now holds a lock from its read to its write.
+//
+// The popup and the background run here as the real modules over one shared
+// storage stub, and share the lock the way the background and a page outside
+// a Firefox private window share the browser's
+// (tests/support/navigatorLocks.js).
+
+const { makeStorageStub } = require("./support/storageStub");
+
+function loadContexts(storage) {
+    jest.resetModules();
+    globalThis.chrome = { storage: { local: storage.local } };
+    return {
+        popup: require("../src/shared/state"),
+        background: require("../src/background/state"),
+        applyChainSwitchFields: require("../src/shared/chainSwitchFields")
+            .applyChainSwitchFields,
+    };
+}
+
+// Lets every pending promise callback run, and then some.
+function nextMacrotask() {
+    return new Promise((resolve) => setImmediate(resolve));
+}
+
+afterEach(() => {
+    delete globalThis.chrome;
+    jest.restoreAllMocks();
+});
+
+test("a network the background switches to during a popup save stays stored", async () => {
+    const storage = makeStorageStub({ autistmask: { networkId: "sepolia" } });
+    const { popup, background, applyChainSwitchFields } = loadContexts(storage);
+    await popup.loadState();
+
+    // The popup navigates, so its save has a change of its own to write.
+    popup.state.currentView = "settings";
+
+    // The popup's save has read the record and is about to write it back when
+    // the user's approval of a site's switch to mainnet reaches the
+    // background. Without the lock the background's whole update runs before
+    // the next macrotask; with it, the update waits for the popup's write.
+    let backgroundSwitch;
+    const realSet = storage.local.set.getMockImplementation();
+    storage.local.set.mockImplementationOnce(async (items) => {
+        backgroundSwitch = background.updateState((fresh) =>
+            applyChainSwitchFields(fresh, "mainnet"),
+        );
+        await nextMacrotask();
+        return realSet(items);
+    });
+
+    await popup.saveState();
+    await backgroundSwitch;
+
+    const stored = storage.read("autistmask");
+    expect(stored.networkId).toBe("mainnet");
+    expect(stored.currentView).toBe("settings");
+});
+
+test("after a save that failed, the next save still keeps a network the background switches to during it", async () => {
+    jest.spyOn(console, "error").mockImplementation(() => {});
+    const storage = makeStorageStub({ autistmask: { networkId: "sepolia" } });
+    const { popup, background, applyChainSwitchFields } = loadContexts(storage);
+    await popup.loadState();
+    popup.state.currentView = "settings";
+
+    // The first save's write is refused, so it gives the lock back having
+    // failed.
+    storage.local.set.mockRejectedValueOnce(new Error("quota exceeded"));
+    await expect(popup.saveState()).rejects.toThrow("quota exceeded");
+
+    // The next save is between its read and its write when the background
+    // switches to mainnet, as in the test above.
+    let backgroundSwitch;
+    const realSet = storage.local.set.getMockImplementation();
+    storage.local.set.mockImplementationOnce(async (items) => {
+        backgroundSwitch = background.updateState((fresh) =>
+            applyChainSwitchFields(fresh, "mainnet"),
+        );
+        await nextMacrotask();
+        return realSet(items);
+    });
+
+    await popup.saveState();
+    await backgroundSwitch;
+
+    const stored = storage.read("autistmask");
+    expect(stored.networkId).toBe("mainnet");
+    expect(stored.currentView).toBe("settings");
+});

tests/support/navigatorLocks.js

@@ -0,0 +1,27 @@
+// `navigator.locks` for the unit tests, which run on node, where there is none.
+//
+// One lock per name: granted in the order it was asked for, and let go when
+// the callback settles, whether it resolved or rejected. That is what the
+// browser's own does for the one call the extension makes,
+// `navigator.locks.request(name, callback)`. Every module a test file loads
+// shares it, as the extension's background and its pages share the browser's,
+// except a page in a Firefox private window (README, "Stored state and its
+// version").
+//
+// Run before each test file by `setupFiles` in package.json.
+
+// For each name, a promise that settles once the last request for it has
+// let the lock go.
+const released = new Map();
+
+function request(name, callback) {
+    const previous = released.get(name) || Promise.resolve();
+    const result = previous.then(() => callback({ name, mode: "exclusive" }));
+    released.set(
+        name,
+        result.catch(() => {}),
+    );
+    return result;
+}
+
+globalThis.navigator = { locks: { request } };

tests/tokenTransferDetail.test.js

@@ -10,7 +10,11 @@
 //
 // Its links open the explorer of the network the transaction was sent on,
 // whichever network is active
-// (https://git.eeqj.de/sneak/AutistMask/issues/584).
+// (https://git.eeqj.de/sneak/AutistMask/issues/584), and the transaction is
+// read from that network's Blockscout, the one Settings has for it
+// (https://git.eeqj.de/sneak/AutistMask/issues/623). Its decoded details name
+// the token, and scale its amount, from what the wallet knows of that
+// network's tokens (https://git.eeqj.de/sneak/AutistMask/issues/629).
 //
 // The row is the one the real history parser makes from the explorer's answer,
 // opened through transactionDetail.show(), which is what a click on the row
@@ -26,10 +30,10 @@ jest.mock("../src/shared/log", () => ({
         warnf: () => {},
         errorf: () => {},
     },
-    debugFetch: async (url) => ({
-        ok: true,
-        json: async () => mockExplorerAnswer(url),
-    }),
+    debugFetch: async (url) => {
+        mockAsked.push(url);
+        return { ok: true, json: async () => mockExplorerAnswer(url) };
+    },
     setRuntimeDebug: () => {},
     isDebug: () => false,
 }));
@@ -44,6 +48,8 @@ const { fetchRecentTransactions } = require("../src/shared/transactions");
 const transactionDetail = require("../src/popup/views/transactionDetail");
 
 const EXPLORER = "https://explorer.example/api/v2";
+// A Blockscout that knows nothing of the transaction.
+const OTHER_EXPLORER = "https://other-explorer.example/api/v2";
 const HOLDER = "0x0000000000000000000000000000000000000a11";
 const RECIPIENT = "0x711e691962E5c054b78071C789A0C8CE657377aD";
 // A token the wallet tracks and the bundled token list does not name.
@@ -56,6 +62,9 @@ const TRANSFER_DATA = new Interface([
     "function transfer(address to, uint256 amount)",
 ]).encodeFunctionData("transfer", [RECIPIENT, 1234500000n]);
 
+// Every URL asked of a Blockscout, in order.
+const mockAsked = [];
+
 // The explorer's answers: the transfer in HOLDER's token transfers, and the
 // transaction itself, sent to the token contract.
 function mockExplorerAnswer(url) {
@@ -149,6 +158,7 @@ beforeEach(() => {
     globalThis.document = makeDocument();
     globalThis.window = { location: { search: "" } };
     state.blockscoutUrl = EXPLORER;
+    state.networkEndpoints = {};
     state.wallets = [
         {
             name: "Main",
@@ -157,6 +167,7 @@ beforeEach(() => {
         },
     ];
     state.trackedTokens = [{ address: TOKEN, symbol: "TDOL", decimals: 6 }];
+    state.networkTrackedTokens = {};
     state.viewData = {};
     state.viewStack = [];
     state.currentView = null;
@@ -188,11 +199,13 @@ test("a token transfer's decoded details name the token contract and the amount
     );
 });
 
-// Mainnet is active and the row was read from Sepolia's explorer. The stub
-// explorer answers whichever network asks, so every link on the screen is
-// drawn.
-test("with mainnet active, a Sepolia transaction's links open the Sepolia explorer", async () => {
+// Mainnet is active, and its Blockscout knows nothing of the transaction. The
+// row was read from the Blockscout Settings remembers for Sepolia, and the
+// screen reads the transaction from there too, so every link on it is drawn.
+test("with mainnet active, a Sepolia transaction is read from Sepolia's Blockscout and its links open the Sepolia explorer", async () => {
     state.networkId = "mainnet";
+    state.blockscoutUrl = OTHER_EXPLORER;
+    state.networkEndpoints = { sepolia: { blockscoutUrl: EXPLORER } };
     const [row] = await fetchRecentTransactions(
         HOLDER,
         EXPLORER,
@@ -217,3 +230,64 @@ test("with mainnet active, a Sepolia transaction's links open the Sepolia explor
         `${sepolia}/address/${RECIPIENT}`,
     ]);
 });
+
+test("with mainnet active and no Blockscout remembered for Sepolia, a Sepolia transaction is asked of Sepolia's default Blockscout", async () => {
+    state.networkId = "mainnet";
+    state.blockscoutUrl = OTHER_EXPLORER;
+    const [row] = await fetchRecentTransactions(
+        HOLDER,
+        EXPLORER,
+        NETWORKS.sepolia.chainId,
+    );
+    mockAsked.length = 0;
+
+    transactionDetail.show(row);
+    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+
+    expect(mockAsked).toEqual([
+        NETWORKS.sepolia.defaultBlockscoutUrl + "/transactions/" + TX_HASH,
+    ]);
+});
+
+// Open the Sepolia transfer's detail screen with mainnet active, and wait for
+// its decoded details.
+async function showSepoliaTransferWithMainnetActive() {
+    state.networkId = "mainnet";
+    state.blockscoutUrl = OTHER_EXPLORER;
+    state.networkEndpoints = { sepolia: { blockscoutUrl: EXPLORER } };
+    const [row] = await fetchRecentTransactions(
+        HOLDER,
+        EXPLORER,
+        NETWORKS.sepolia.chainId,
+    );
+    transactionDetail.show(row);
+    for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
+}
+
+test("with mainnet active, a Sepolia token transfer's decoded details name the token tracked on Sepolia and its amount at its scale", async () => {
+    state.trackedTokens = [];
+    state.networkTrackedTokens = {
+        sepolia: [{ address: TOKEN, symbol: "TDOL", decimals: 6 }],
+    };
+    await showSepoliaTransferWithMainnetActive();
+
+    expect(decodedLine("Token")).toContain('<div class="font-bold">TDOL</div>');
+    expect(decodedLine("Amount")).toContain(
+        '<div class="font-bold">1234.5000 TDOL</div>',
+    );
+});
+
+// The same contract address on mainnet is another token, so what the wallet
+// tracks and holds there names nothing on Sepolia.
+test("with mainnet active, a Sepolia token transfer's decoded details take nothing from mainnet's tracked tokens or balances", async () => {
+    state.trackedTokens = [{ address: TOKEN, symbol: "MDOL", decimals: 18 }];
+    state.wallets[0].addresses[0].tokenBalances = [
+        { address: TOKEN, symbol: "MDOL", decimals: 18, balance: "1.0" },
+    ];
+    await showSepoliaTransferWithMainnetActive();
+
+    expect(decodedLine("Token")).not.toContain("MDOL");
+    expect(decodedLine("Amount")).toContain(
+        '<div class="font-bold">1234500000 base units (decimals unknown)</div>',
+    );
+});

tests/txStatus.test.js

@@ -150,6 +150,8 @@ beforeEach(() => {
     state.rpcUrl = NETWORKS.mainnet.defaultRpcUrl;
     state.networkEndpoints = {};
     state.wallets = [];
+    state.trackedTokens = [];
+    state.networkTrackedTokens = {};
     state.viewData = {};
     state.viewStack = [];
     state.currentView = null;
@@ -627,6 +629,31 @@ describe("SuccessTx and ErrorTx for a Sepolia transaction with mainnet active",
         expectSepoliaLinks();
     });
 
+    // https://git.eeqj.de/sneak/AutistMask/issues/629
+    test("SuccessTx's decoded action names the token from the tokens tracked on Sepolia", async () => {
+        function expectTokenNamed() {
+            expect(getElement("success-tx-decoded").innerHTML).toContain(
+                '<div class="font-bold">TDOL</div>',
+            );
+        }
+        state.networkTrackedTokens = {
+            sepolia: [{ address: TOKEN, symbol: "TDOL", decimals: 6 }],
+        };
+        const decoded = {
+            name: "Transfer",
+            details: [{ label: "Token", address: TOKEN, isToken: true }],
+        };
+        mockReceiptLookup.mockResolvedValue({ blockNumber: 21000000 });
+        txStatus.showWait({ ...sepoliaTx, decoded }, TX_HASH);
+        await jest.advanceTimersByTimeAsync(10000);
+        expect(state.currentView).toBe("success-tx");
+        expectTokenNamed();
+
+        elements.clear();
+        txStatus.renderSuccess();
+        expectTokenNamed();
+    });
+
     test("the recipient and hash on ErrorTx link to the Sepolia explorer", () => {
         function expectSepoliaLinks() {
             expect(getElement("error-tx-to").innerHTML).toContain(

tests/uniswapRecipient.test.js

@@ -7,9 +7,12 @@
 // (https://git.eeqj.de/sneak/AutistMask/issues/592), the address whose
 // balance a BALANCE_CHECK_ERC20 checks
 // (https://git.eeqj.de/sneak/AutistMask/issues/600), any token a swap
-// leaves in the router (https://git.eeqj.de/sneak/AutistMask/issues/606), and
+// leaves in the router (https://git.eeqj.de/sneak/AutistMask/issues/606),
 // what each PERMIT2_TRANSFER_FROM moves
-// (https://git.eeqj.de/sneak/AutistMask/issues/611).
+// (https://git.eeqj.de/sneak/AutistMask/issues/611), and when an
+// UNWRAP_WETH makes the output ETH
+// (https://git.eeqj.de/sneak/AutistMask/issues/607 and
+// https://git.eeqj.de/sneak/AutistMask/issues/642).
 //
 // Every swap command, SWEEP, WRAP_ETH, UNWRAP_WETH, TRANSFER, PAY_PORTION,
 // PAY_PORTION_FULL_PRECISION, PERMIT2_TRANSFER_FROM, ACROSS_V4_DEPOSIT_V3 and
@@ -268,18 +271,28 @@ const SWAP_USDT_FOR_ETH = [
         [[[ZERO, USDT, 500, 10, ZERO], false, USDT_2000, ONE_WETH, "0x"]],
     ),
 ];
+const SWAP_USDT_FOR_WETH = [
+    0x06, // SWAP_EXACT_IN_SINGLE
+    coder.encode(
+        [
+            "tuple(tuple(address,address,uint24,int24,address),bool,uint128,uint128,bytes)",
+        ],
+        [[[USDT, WETH, 500, 10, ZERO], true, USDT_2000, ONE_WETH, "0x"]],
+    ),
+];
 // SWAP_EXACT_IN_SINGLE with no parameters, which cannot be read.
 const UNREADABLE_SWAP = [0x06, "0x"];
 const SETTLE_USDT = [
     0x0b,
     coder.encode(["address", "uint256", "bool"], [USDT, 0n, true]),
 ];
-function take(currency, recipient) {
+// A TAKE of `amount`, by default zero: the open delta, all the step owes.
+function take(currency, recipient, amount = 0n) {
     return [
         0x0e,
         coder.encode(
             ["address", "address", "uint256"],
-            [currency, recipient, 0n],
+            [currency, recipient, amount],
         ),
     ];
 }
@@ -387,6 +400,18 @@ describe("each swap command's recipient", () => {
             data: (r) => execute(swapToWeth(r)),
             min: "1.0000 WETH",
         },
+        {
+            // Its input has V3_SWAP_EXACT_IN's layout, with amountOut and
+            // amountInMax in place of amountIn and amountOutMin, and a path
+            // that lists the token bought first.
+            kind: "V3_SWAP_EXACT_OUT",
+            data: (r) =>
+                execute([
+                    0x01,
+                    v3SwapExactIn(r, ONE_WETH, USDT_2000, WETH, USDT)[1],
+                ]),
+            min: "1.0000 WETH",
+        },
         {
             kind: "V4_SWAP with TAKE",
             data: (r) =>
@@ -519,7 +544,7 @@ describe("an output left in the router is not received", () => {
         {
             kind: "an UNWRAP_WETH to the user, then the swap",
             data: execute(unwrapWeth(MSG_SENDER), toRouter),
-            min: "1.0000 ETH",
+            min: "1.0000 WETH",
         },
         {
             kind: "the swap, then a WRAP_ETH of zero to the user",
@@ -556,6 +581,530 @@ describe("an output left in the router is not received", () => {
     });
 });
 
+// https://git.eeqj.de/sneak/AutistMask/issues/607: an UNWRAP_WETH pays out,
+// as ETH, the WETH the router holds when it runs. Token Out read ETH whenever
+// the output side was WETH, so a swap that paid its WETH to the user before
+// the UNWRAP_WETH read as ETH, though the user receives WETH.
+describe("an UNWRAP_WETH makes the output ETH only when the router holds it", () => {
+    test("a swap paying its WETH to the user, then an UNWRAP_WETH, reads as WETH", () => {
+        const result = decode(
+            execute(swapToWeth(MSG_SENDER), unwrapWeth(MSG_SENDER)),
+        );
+        expect(result.name).toBe("Swap USDT → WETH");
+        expect(labels(result)).toEqual(PAID_TO_USER);
+        expect(detail(result, "Min. received").value).toBe("1.0000 WETH");
+    });
+
+    test("a swap paying its WETH to the router, then an UNWRAP_WETH to the user, reads as ETH", () => {
+        const result = decode(
+            execute(swapToWeth(ADDRESS_THIS), unwrapWeth(MSG_SENDER)),
+        );
+        expect(result.name).toBe("Swap USDT → ETH");
+        expect(labels(result)).toEqual(PAID_TO_USER);
+        expect(detail(result, "Min. received").value).toBe("1.0000 ETH");
+    });
+
+    // The SWEEP pays the user all the WETH the router holds, so the
+    // UNWRAP_WETH finds none of it.
+    test("a swap paying its WETH to the router, then a SWEEP of it to the user, then an UNWRAP_WETH, reads as WETH", () => {
+        const result = decode(
+            execute(
+                swapToWeth(ADDRESS_THIS),
+                sweep(WETH, MSG_SENDER),
+                unwrapWeth(MSG_SENDER),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → WETH");
+        expect(detail(result, "Min. received").value).toBe("1.0000 WETH");
+    });
+
+    // The user receives the first step's WETH as WETH and the second's as
+    // ETH. The second step sets the output side and pays its WETH to the
+    // router, so the output reads as ETH with the second step's minimum.
+    test("two swaps, the second paying its WETH to the router, then an UNWRAP_WETH, reads as ETH", () => {
+        const result = decode(
+            execute(
+                swapToWeth(MSG_SENDER),
+                v2Swap(0x08, ADDRESS_THIS, USDC_1990, ONE_WETH / 2n, [
+                    USDC,
+                    WETH,
+                ]),
+                unwrapWeth(MSG_SENDER),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → ETH");
+        expect(detail(result, "Min. received").value).toBe("0.5000 ETH");
+    });
+
+    // The same two swaps the other way round. The user receives the first
+    // step's WETH as ETH and the second's as WETH. The second step sets the
+    // output side and pays its WETH to the user, so the output reads as WETH
+    // with the second step's minimum, though the router holds the first's.
+    test("two swaps, the second paying its WETH to the user, then an UNWRAP_WETH, reads as WETH", () => {
+        const result = decode(
+            execute(
+                v2Swap(0x08, ADDRESS_THIS, USDC_1990, ONE_WETH / 2n, [
+                    USDC,
+                    WETH,
+                ]),
+                swapToWeth(MSG_SENDER),
+                unwrapWeth(MSG_SENDER),
+            ),
+        );
+        expect(result.name).toBe("Swap USDC → WETH");
+        expect(detail(result, "Min. received").value).toBe("1.0000 WETH");
+    });
+
+    // One V4 step buys at least 1 WETH and TAKEs 0.6 WETH to the user and the
+    // rest to the router. The user receives 0.6 WETH and the rest as ETH.
+    // Neither minimum is shown: the decoder does not count how much of the
+    // step's minimum reaches the router, nor read the UNWRAP_WETH's own.
+    test("one V4 step paying part of its WETH to the user and the rest to the router, then an UNWRAP_WETH, 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),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → ETH");
+        expect(labels(result)).toEqual([
+            "Protocol",
+            "Token In",
+            "Amount",
+            "Token Out",
+            "Steps",
+            "Deadline",
+        ]);
+    });
+
+    // 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(
+            execute(
+                v4Swap(
+                    SWAP_USDT_FOR_WETH,
+                    SETTLE_USDT,
+                    withDirtyWord(take(WETH, MSG_SENDER), 1),
+                    take(WETH, ADDRESS_THIS),
+                ),
+                unwrapWeth(MSG_SENDER),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → ETH");
+        expect(detail(result, "Min. received")).toBeUndefined();
+        expect(detail(result, "Min. paid out")).toBeUndefined();
+    });
+
+    // A step after the UNWRAP_WETH that sets the output side sets it anew.
+    test("a swap paying WETH to the user after an UNWRAP_WETH of an earlier swap's WETH reads as WETH", () => {
+        const result = decode(
+            execute(
+                swapToWeth(ADDRESS_THIS),
+                unwrapWeth(MSG_SENDER),
+                v2Swap(0x08, MSG_SENDER, USDC_1990, ONE_WETH / 2n, [
+                    USDC,
+                    WETH,
+                ]),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → WETH");
+        expect(detail(result, "Min. received").value).toBe("0.5000 WETH");
+    });
+
+    // The EXECUTE_SUB_PLAN's own steps, which the decoder does not read, buy
+    // the user USDC as well, so Token Out is not named.
+    test("a swap paying its WETH to the router, then an UNWRAP_WETH, then an EXECUTE_SUB_PLAN, names no Token Out", () => {
+        const subPlan = [
+            0x21,
+            coder.encode(
+                ["bytes", "bytes[]"],
+                [
+                    "0x00",
+                    [
+                        v3SwapExactIn(
+                            MSG_SENDER,
+                            USDT_2000,
+                            USDC_1990,
+                            USDT,
+                            USDC,
+                        )[1],
+                    ],
+                ],
+            ),
+        ];
+        const result = decode(
+            execute(swapToWeth(ADDRESS_THIS), unwrapWeth(MSG_SENDER), subPlan),
+        );
+        expect(result.name).toBe("Uniswap Swap");
+        expect(detail(result, "Token Out").value).toBe(UNDECODED);
+        expect(detail(result, "Min. received")).toBeUndefined();
+    });
+});
+
+// https://git.eeqj.de/sneak/AutistMask/issues/642: a step between the swap and
+// the UNWRAP_WETH may take WETH out of the router or pay it WETH, and a step
+// after an UNWRAP_WETH into the router may pay its ETH out as WETH, yet each
+// route read as ETH with the swap's minimum. A step the decoder read that is a
+// PERMIT2_PERMIT, a BALANCE_CHECK_ERC20, or a SWEEP, TRANSFER, PAY_PORTION or
+// PAY_PORTION_FULL_PRECISION of a token other than WETH, and not of ETH to a
+// WETH contract, cannot take WETH out of the router or pay anyone WETH; the
+// decoder treats every other step as one that may.
+describe("what reaches the UNWRAP_WETH of the swap's WETH", () => {
+    const NO_MINIMUM_TO_USER = PAID_TO_USER.filter(
+        (l) => l !== "Min. received",
+    );
+    const NO_MINIMUM_ELSEWHERE = PAID_ELSEWHERE.filter(
+        (l) => l !== "Min. paid out",
+    );
+
+    test.each([
+        {
+            kind: "a TRANSFER of 0.0025 WETH",
+            step: transfer(0x05, WETH, OTHER, ONE_WETH / 400n),
+        },
+        {
+            kind: "a PAY_PORTION of 25 bips",
+            step: transfer(0x06, WETH, OTHER, 25n),
+        },
+        {
+            kind: "a PAY_PORTION_FULL_PRECISION of 1e15",
+            step: transfer(0x07, WETH, OTHER, 10n ** 15n),
+        },
+    ])(
+        "$kind to another address between them reads as ETH with no minimum",
+        ({ step }) => {
+            const result = decode(
+                execute(swapToWeth(ADDRESS_THIS), step, unwrapWeth(MSG_SENDER)),
+                USER,
+                ROUTER_V2_1_2,
+            );
+            expect(result.name).toBe("Swap USDT → ETH");
+            expect(labels(result)).toEqual(NO_MINIMUM_ELSEWHERE);
+            expect(paidTo(result)).toEqual([OTHER]);
+        },
+    );
+
+    test.each([
+        {
+            kind: "a SWEEP whose recipient cannot be read",
+            step: withDirtyWord(sweep(WETH, OTHER), 1),
+        },
+        {
+            kind: "a V4 SETTLE of 0.5 WETH from the router",
+            step: v4Swap([
+                0x0b,
+                coder.encode(
+                    ["address", "uint256", "bool"],
+                    [WETH, ONE_WETH / 2n, false],
+                ),
+            ]),
+        },
+        {
+            kind: "a bridge deposit of 0.5 WETH",
+            step: acrossDeposit(USER, USER, WETH, ONE_WETH / 2n),
+        },
+        {
+            kind: "a PERMIT2_TRANSFER_FROM of 0.5 WETH into the router",
+            step: permit2TransferFrom(WETH, ADDRESS_THIS, ONE_WETH / 2n),
+        },
+    ])("$kind between them reads as ETH with no minimum", ({ step }) => {
+        const result = decode(
+            execute(swapToWeth(ADDRESS_THIS), step, unwrapWeth(MSG_SENDER)),
+        );
+        expect(result.name).toBe("Swap USDT → ETH");
+        expect(detail(result, "Min. received")).toBeUndefined();
+        expect(detail(result, "Min. paid out")).toBeUndefined();
+    });
+
+    test.each([
+        {
+            kind: "a PERMIT2_PERMIT between them",
+            steps: [permit2Permit(USDT, USDT_2000), unwrapWeth(MSG_SENDER)],
+        },
+        {
+            kind: "a BALANCE_CHECK_ERC20 of another address between them",
+            steps: [balanceCheck(USDC, 1n, OTHER), unwrapWeth(MSG_SENDER)],
+        },
+        {
+            kind: "a BALANCE_CHECK_ERC20 of the sender with a zero minimum between them",
+            steps: [balanceCheck(USDC, 0n), unwrapWeth(MSG_SENDER)],
+        },
+        {
+            kind: "a SWEEP of USDC between them",
+            steps: [sweep(USDC, MSG_SENDER), unwrapWeth(MSG_SENDER)],
+        },
+        {
+            kind: "an UNWRAP_WETH into the router, then a SWEEP of its ETH,",
+            steps: [unwrapWeth(ADDRESS_THIS), sweep(ZERO, MSG_SENDER)],
+        },
+    ])("$kind reads as ETH with the swap's minimum", ({ steps }) => {
+        const result = decode(execute(swapToWeth(ADDRESS_THIS), ...steps));
+        expect(result.name).toBe("Swap USDT → ETH");
+        expect(detail(result, "Min. received").value).toBe("1.0000 ETH");
+    });
+
+    test("a V4 step that TAKEs its WETH to the router, then an UNWRAP_WETH to the user, reads as ETH with the swap's minimum", () => {
+        const result = decode(
+            execute(
+                v4Swap(
+                    SWAP_USDT_FOR_WETH,
+                    SETTLE_USDT,
+                    take(WETH, ADDRESS_THIS),
+                ),
+                unwrapWeth(MSG_SENDER),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → ETH");
+        expect(detail(result, "Min. received").value).toBe("1.0000 ETH");
+    });
+
+    test.each([
+        {
+            kind: "a TRANSFER of 100 USDC",
+            step: transfer(0x05, USDC, OTHER, 100000000n),
+        },
+        {
+            kind: "a PAY_PORTION of 25 bips of USDC",
+            step: transfer(0x06, USDC, OTHER, 25n),
+        },
+        {
+            kind: "a PAY_PORTION_FULL_PRECISION of 1e15 of USDC",
+            step: transfer(0x07, USDC, OTHER, 10n ** 15n),
+        },
+    ])(
+        "$kind to another address between them reads as ETH with the swap's minimum",
+        ({ step }) => {
+            const result = decode(
+                execute(swapToWeth(ADDRESS_THIS), step, unwrapWeth(MSG_SENDER)),
+                USER,
+                ROUTER_V2_1_2,
+            );
+            expect(result.name).toBe("Swap USDT → ETH");
+            expect(paidTo(result)).toEqual([OTHER]);
+            expect(detail(result, "Min. paid out").value).toBe("1.0000 ETH");
+        },
+    );
+
+    test.each([
+        {
+            kind: "a TRANSFER of 0.0025 ETH",
+            step: transfer(0x05, ZERO, OTHER, ONE_WETH / 400n),
+        },
+        {
+            kind: "a PAY_PORTION of 25 bips of its ETH",
+            step: transfer(0x06, ZERO, OTHER, 25n),
+        },
+        {
+            kind: "a PAY_PORTION_FULL_PRECISION of 1e15 of its ETH",
+            step: transfer(0x07, ZERO, OTHER, 10n ** 15n),
+        },
+    ])(
+        "an UNWRAP_WETH into the router, then $kind to another address, then a SWEEP of its ETH to the user, reads as ETH with the swap's minimum",
+        ({ step }) => {
+            const result = decode(
+                execute(
+                    swapToWeth(ADDRESS_THIS),
+                    unwrapWeth(ADDRESS_THIS),
+                    step,
+                    sweep(ZERO, MSG_SENDER),
+                ),
+                USER,
+                ROUTER_V2_1_2,
+            );
+            expect(result.name).toBe("Swap USDT → ETH");
+            expect(paidTo(result)).toEqual([OTHER]);
+            expect(detail(result, "Min. paid out").value).toBe("1.0000 ETH");
+        },
+    );
+
+    // The SWEEP pays the user the swap's WETH, so the UNWRAP_WETH unwraps the
+    // WRAP_ETH's.
+    test("a SWEEP of the swap's WETH to the user, then a WRAP_ETH into the router, reads as ETH with no minimum", () => {
+        const result = decode(
+            execute(
+                swapToWeth(ADDRESS_THIS),
+                sweep(WETH, MSG_SENDER),
+                wrapEth(ADDRESS_THIS, ONE_WETH),
+                unwrapWeth(MSG_SENDER),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → ETH");
+        expect(labels(result)).toEqual(NO_MINIMUM_TO_USER);
+    });
+
+    test("an UNWRAP_WETH into the router, then a WRAP_ETH of all its ETH to the user, reads as WETH with no minimum", () => {
+        const result = decode(
+            execute(
+                swapToWeth(ADDRESS_THIS),
+                unwrapWeth(ADDRESS_THIS),
+                wrapEth(MSG_SENDER, CONTRACT_BALANCE),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → WETH");
+        expect(labels(result)).toEqual(NO_MINIMUM_TO_USER);
+    });
+
+    // The router reads the recipient from the last 20 bytes of its word,
+    // here address(2), the router itself.
+    test("an UNWRAP_WETH whose recipient cannot be read, then a WRAP_ETH of all the router's ETH to the user, reads as WETH with no minimum", () => {
+        const result = decode(
+            execute(
+                swapToWeth(ADDRESS_THIS),
+                withDirtyWord(unwrapWeth(ADDRESS_THIS), 0),
+                wrapEth(MSG_SENDER, CONTRACT_BALANCE),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → WETH");
+        expect(detail(result, "Min. received")).toBeUndefined();
+        expect(detail(result, "Min. paid out")).toBeUndefined();
+    });
+
+    // The first UNWRAP_WETH may pay the router the swap's output as ETH, and
+    // the WRAP_ETH to the user pays all of it out as WETH, so the last
+    // UNWRAP_WETH finds none of it.
+    test.each([
+        {
+            kind: "an UNWRAP_WETH whose recipient cannot be read, then a WRAP_ETH of all the router's ETH to the user",
+            steps: [
+                withDirtyWord(unwrapWeth(ADDRESS_THIS), 0),
+                wrapEth(MSG_SENDER, CONTRACT_BALANCE),
+            ],
+        },
+        {
+            kind: "an UNWRAP_WETH into the router, a WRAP_ETH of all its ETH to the user, then a WRAP_ETH of all its ETH into the router",
+            steps: [
+                unwrapWeth(ADDRESS_THIS),
+                wrapEth(MSG_SENDER, CONTRACT_BALANCE),
+                wrapEth(ADDRESS_THIS, CONTRACT_BALANCE),
+            ],
+        },
+    ])(
+        "$kind, then an UNWRAP_WETH to the user, reads as WETH with no minimum",
+        ({ steps }) => {
+            const result = decode(
+                execute(
+                    swapToWeth(ADDRESS_THIS),
+                    ...steps,
+                    unwrapWeth(MSG_SENDER),
+                ),
+            );
+            expect(result.name).toBe("Swap USDT → WETH");
+            expect(detail(result, "Min. received")).toBeUndefined();
+            expect(detail(result, "Min. paid out")).toBeUndefined();
+        },
+    );
+
+    // A SWEEP of WETH pays out WETH, and ETH paid to a WETH contract pays the
+    // router WETH for it. The decoder treats each as a step that may pay out
+    // as WETH the swap's output, which the router holds as ETH.
+    test.each([
+        {
+            kind: "a SWEEP of WETH to the user",
+            step: sweep(WETH, MSG_SENDER),
+        },
+        {
+            kind: "a SWEEP of its ETH to the WETH contract",
+            step: sweep(ZERO, WETH),
+        },
+        {
+            kind: "a TRANSFER of 0.5 ETH to the WETH contract",
+            step: transfer(0x05, ZERO, WETH, ONE_WETH / 2n),
+        },
+        {
+            kind: "a PAY_PORTION of all its ETH to the WETH contract",
+            step: transfer(0x06, ZERO, WETH, 10000n),
+        },
+    ])(
+        "an UNWRAP_WETH into the router, then $kind, reads as WETH with no minimum",
+        ({ step }) => {
+            const result = decode(
+                execute(
+                    swapToWeth(ADDRESS_THIS),
+                    unwrapWeth(ADDRESS_THIS),
+                    step,
+                ),
+            );
+            expect(result.name).toBe("Swap USDT → WETH");
+            expect(detail(result, "Min. received")).toBeUndefined();
+            expect(detail(result, "Min. paid out")).toBeUndefined();
+        },
+    );
+
+    // The user receives 0.5 WETH and the rest of the swap's output as ETH.
+    test("an UNWRAP_WETH into the router, then a WRAP_ETH of 0.5 ETH to the user, reads as WETH with no minimum", () => {
+        const result = decode(
+            execute(
+                swapToWeth(ADDRESS_THIS),
+                unwrapWeth(ADDRESS_THIS),
+                wrapEth(MSG_SENDER, ONE_WETH / 2n),
+                sweep(ZERO, MSG_SENDER),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → WETH");
+        expect(labels(result)).toEqual(NO_MINIMUM_TO_USER);
+    });
+
+    // The UNWRAP_WETH pays the user the swap's WETH as ETH; the WRAP_ETH wraps
+    // the ETH an earlier V4 step paid the router.
+    test("an UNWRAP_WETH to the user, then a WRAP_ETH of all the router's ETH to the user, reads as ETH", () => {
+        const result = decode(
+            execute(
+                v4Swap(
+                    SWAP_USDT_FOR_ETH,
+                    SETTLE_USDT,
+                    take(ZERO, ADDRESS_THIS),
+                ),
+                swapToWeth(ADDRESS_THIS),
+                unwrapWeth(MSG_SENDER),
+                wrapEth(MSG_SENDER, CONTRACT_BALANCE),
+            ),
+        );
+        expect(detail(result, "Token Out").value).toBe("ETH");
+        expect(detail(result, "Min. received").value).toBe("1.0000 ETH");
+    });
+
+    // The first swap is for at least 0.5 WETH and the second for at least
+    // 1 WETH. The second sets the output side again, so the first
+    // UNWRAP_WETH into the router no longer bears on it.
+    test.each([
+        { kind: "a V3 swap step", step: swapToWeth(ADDRESS_THIS) },
+        {
+            kind: "a V4 step that TAKEs its WETH to the router",
+            step: v4Swap(
+                SWAP_USDT_FOR_WETH,
+                SETTLE_USDT,
+                take(WETH, ADDRESS_THIS),
+            ),
+        },
+    ])(
+        "a swap paying WETH to the router, an UNWRAP_WETH into the router, a SWEEP of its ETH to the user, then $kind and an UNWRAP_WETH to the user, reads as ETH with the second swap's minimum",
+        ({ step }) => {
+            const result = decode(
+                execute(
+                    v3SwapExactIn(
+                        ADDRESS_THIS,
+                        USDT_2000,
+                        ONE_WETH / 2n,
+                        USDT,
+                        WETH,
+                    ),
+                    unwrapWeth(ADDRESS_THIS),
+                    sweep(ZERO, MSG_SENDER),
+                    step,
+                    unwrapWeth(MSG_SENDER),
+                ),
+            );
+            expect(result.name).toBe("Swap USDT → ETH");
+            expect(detail(result, "Min. received").value).toBe("1.0000 ETH");
+        },
+    );
+});
+
 // https://git.eeqj.de/sneak/AutistMask/issues/606: any token a step pays the
 // router stays there unless a later step pays out or spends all of it, not
 // only the swap's output. A V4 SETTLE can take more of the user's tokens than
@@ -1522,15 +2071,6 @@ describe("a payout of part of the router's output", () => {
             ),
             min: "1.0000 WETH",
         },
-        {
-            kind: "PAY_PORTION of 25 bips, then UNWRAP_WETH",
-            data: execute(
-                swapToWeth(ADDRESS_THIS),
-                transfer(0x06, WETH, OTHER, 25n),
-                unwrapWeth(MSG_SENDER),
-            ),
-            min: "1.0000 ETH",
-        },
         {
             kind: "V4 TAKE_PORTION of 25 bips, then TAKE_ALL",
             data: execute(
@@ -2019,10 +2559,6 @@ describe("a payout that cannot be read is never said to be received", () => {
                 ),
             ],
         },
-        {
-            kind: "V3_SWAP_EXACT_OUT",
-            step: [0x01, swapToWeth(OTHER)[1]],
-        },
         {
             kind: "EXECUTE_SUB_PLAN",
             step: [
@@ -2273,7 +2809,7 @@ describe("the allow-revert flag", () => {
             mark: " (allowed to fail)",
         },
     ])(
-        "on $router, a PERMIT2_PERMIT with the flag is listed as 'Permit2 Permit$mark', and the swap reads as without the flag",
+        "on $router, a PERMIT2_PERMIT with the flag is listed as 'Permit2 Permit$mark', and the swap's lines read as without the flag",
         ({ address, mark }) => {
             const steps = [
                 permit2Permit(USDT, USDT_2000),
@@ -2288,9 +2824,24 @@ describe("the allow-revert flag", () => {
             expect(detail(withFlag, "Steps").value).toBe(
                 "Permit2 Permit" + mark + " → V3 Swap (Exact In)",
             );
-            const withoutSteps = (r) =>
-                r.details.filter((d) => d.label !== "Steps");
-            expect(withoutSteps(withFlag)).toEqual(withoutSteps(plain));
+            // The permit names the router at ROUTER as its spender, so its
+            // amount stands as the Amount figure only there, and only without
+            // the flag. With the flag it stands on no router and gets lines
+            // of its own, and the swap step names Token In: the same token,
+            // its address written the same way.
+            const permitLines = [
+                "Permit2 allowance",
+                "Allowance token",
+                "Allowance spender",
+            ];
+            const swapLines = (r) =>
+                r.details.filter(
+                    (d) => !["Steps", ...permitLines].includes(d.label),
+                );
+            expect(swapLines(withFlag)).toEqual(swapLines(plain));
+            expect(
+                labels(withFlag).filter((l) => permitLines.includes(l)),
+            ).toEqual(permitLines);
             expect(detail(withFlag, "Min. received").value).toBe("1.0000 WETH");
         },
     );

tests/uniswapRouterAddress.test.js

@@ -7,6 +7,12 @@
 // only when the transaction is sent to a Universal Router deployment on the
 // network it is for; anywhere else it is left to the raw data.
 //
+// The transaction history labelled any call named `execute` or `multicall` a
+// Swap, whatever address it went to
+// (https://git.eeqj.de/sneak/AutistMask/issues/580). It now does so only for
+// such a call sent to a Universal Router deployment on the network the
+// transaction is on; any other is labelled by its method name.
+//
 // The transaction detail screen and the approval screen are driven against a
 // minimal DOM stub in the shape tests/tokenTransferDetail.test.js uses, the
 // approval screen opened the way tests/swapStatusAmount.test.js opens it.
@@ -33,6 +39,7 @@ globalThis.chrome = {
 };
 
 const { state } = require("../src/shared/state");
+const { fetchRecentTransactions } = require("../src/shared/transactions");
 const approval = require("../src/popup/views/approval");
 const { decodeCalldata } = approval;
 const transactionDetail = require("../src/popup/views/transactionDetail");
@@ -47,6 +54,8 @@ const SEPOLIA_ROUTER = "0x3a9d48ab9751398bbfa63ad67599bb04e4bdf98b";
 const ROUTER_ON_BOTH = "0x3fC91A3afd70395Cd496C647d5a6CC9D4B2b7FAD";
 // The address with no code from the issue.
 const ORDINARY = "0x0b0050Da68435b3EcBC236c40F16dB2070bCD79A";
+// A contract that is not a router, such as a multisig.
+const OTHER_CONTRACT = "0x5afe000000000000000000000000000000005afe";
 
 const RECIPIENT = "0xC0FfEE0000000000000000000000000000c0fFEe";
 const SEPOLIA_WETH = "0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14";
@@ -129,8 +138,13 @@ describe("execute() calldata on the approval screen's decoder", () => {
 // The transaction the explorer reports: SWAP_DATA, sent to `mockSentTo`.
 const TX_HASH = "0x" + "5".repeat(64);
 let mockSentTo = null;
+// The transactions the explorer reports for RECIPIENT's history.
+let mockHistory = [];
 
 function mockExplorerAnswer(url) {
+    if (url.endsWith("/addresses/" + RECIPIENT + "/transactions")) {
+        return { items: mockHistory };
+    }
     if (url.endsWith("/transactions/" + TX_HASH)) {
         return {
             to: { hash: mockSentTo },
@@ -186,57 +200,126 @@ function node(id) {
     return globalThis.document.getElementById(id);
 }
 
-// Open the transaction detail screen with Sepolia active, for the
-// transaction the explorer reports sent to `sentTo`, and wait for its
-// decoded details.
-async function showDetailSentTo(sentTo) {
-    mockSentTo = sentTo;
+// Open the transaction detail screen with `activeNetworkId` active, for the
+// history row `row`, and wait for its decoded details.
+async function showDetail(row, activeNetworkId) {
+    mockSentTo = row.to;
     globalThis.document = makeDocument();
     globalThis.window = { location: { search: "" } };
-    state.networkId = "sepolia";
+    state.networkId = activeNetworkId;
     state.blockscoutUrl = "https://explorer.example/api/v2";
     state.viewData = {};
     state.viewStack = [];
     state.currentView = null;
-    transactionDetail.show({
-        hash: TX_HASH,
-        from: RECIPIENT,
-        to: sentTo,
-        value: "",
-        symbol: "SepoliaETH",
-        timestamp: 1790000000,
-        isError: false,
-        direction: "contract",
-        directionLabel: "Swap",
-        method: "execute",
-        chainId: SEPOLIA,
-    });
+    transactionDetail.show(row);
     for (let i = 0; i < 10; i++) await new Promise((r) => setTimeout(r, 0));
 }
 
+// Open the transaction detail screen with `activeNetworkId` active, for the
+// Sepolia transaction the explorer reports sent to `sentTo`, and wait for its
+// decoded details.
+async function showDetailSentTo(sentTo, activeNetworkId) {
+    await showDetail(
+        {
+            hash: TX_HASH,
+            from: RECIPIENT,
+            to: sentTo,
+            value: "",
+            symbol: "SepoliaETH",
+            timestamp: 1790000000,
+            isError: false,
+            direction: "contract",
+            directionLabel: "Swap",
+            method: "execute",
+            chainId: SEPOLIA,
+        },
+        activeNetworkId,
+    );
+}
+
 describe("execute() calldata on the transaction detail screen", () => {
     test("sent to a router on the active network, it is a swap", async () => {
-        await showDetailSentTo(SEPOLIA_ROUTER);
+        await showDetailSentTo(SEPOLIA_ROUTER, "sepolia");
+        expect(node("tx-detail-calldata-details").innerHTML).toContain(
+            "Swap via Uniswap Universal Router",
+        );
+    });
+
+    // https://git.eeqj.de/sneak/AutistMask/issues/623
+    test("sent to a router on its network, with the other network active, it is a swap", async () => {
+        await showDetailSentTo(SEPOLIA_ROUTER, "mainnet");
         expect(node("tx-detail-calldata-details").innerHTML).toContain(
             "Swap via Uniswap Universal Router",
         );
     });
 
     test("sent to an ordinary address, it is not decoded", async () => {
-        await showDetailSentTo(ORDINARY);
+        await showDetailSentTo(ORDINARY, "sepolia");
         expect(node("tx-detail-calldata-action").textContent).toBe("execute");
         expect(node("tx-detail-calldata-details").innerHTML).toBe("");
         expect(node("tx-detail-rawdata").innerHTML).toContain(SWAP_DATA);
     });
 
     test("sent to a router of the other network only, it is not decoded", async () => {
-        await showDetailSentTo(MAINNET_ROUTER);
+        await showDetailSentTo(MAINNET_ROUTER, "sepolia");
         expect(node("tx-detail-calldata-action").textContent).toBe("execute");
         expect(node("tx-detail-calldata-details").innerHTML).toBe("");
         expect(node("tx-detail-rawdata").innerHTML).toContain(SWAP_DATA);
     });
 });
 
+// The history row made from the explorer's answer for RECIPIENT's `method`
+// call sent to the contract `sentTo` on the network with `chainId`. The
+// explorer gives the address in checksummed form.
+async function historyRow(method, sentTo, chainId) {
+    mockHistory = [
+        {
+            hash: TX_HASH,
+            block_number: 7000000,
+            timestamp: "2026-09-01T00:00:00Z",
+            from: { hash: RECIPIENT },
+            to: { hash: getAddress(sentTo), is_contract: true },
+            value: "0",
+            method,
+            status: "ok",
+        },
+    ];
+    const rows = await fetchRecentTransactions(
+        RECIPIENT,
+        "https://explorer.example/api/v2",
+        chainId,
+    );
+    return rows[0];
+}
+
+// The history row's label and TransactionDetail's Type line, for a Sepolia
+// transaction. The active network does not decide either.
+describe.each([
+    ["execute", "Execute"],
+    ["multicall", "Multicall"],
+])("a %s() call in the history", (method, methodLabel) => {
+    test("sent to a router on its network, it is a Swap", async () => {
+        const row = await historyRow(method, SEPOLIA_ROUTER, SEPOLIA);
+        expect(row.directionLabel).toBe("Swap");
+        await showDetail(row, "mainnet");
+        expect(node("tx-detail-type").textContent).toBe("Swap");
+    });
+
+    test("sent to another contract, it is labelled by its method name", async () => {
+        const row = await historyRow(method, OTHER_CONTRACT, SEPOLIA);
+        expect(row.directionLabel).toBe(methodLabel);
+        await showDetail(row, "sepolia");
+        expect(node("tx-detail-type").textContent).toBe("Contract Call");
+    });
+
+    test("sent to a router of the other network only, it is labelled by its method name", async () => {
+        const row = await historyRow(method, MAINNET_ROUTER, SEPOLIA);
+        expect(row.directionLabel).toBe(methodLabel);
+        await showDetail(row, "mainnet");
+        expect(node("tx-detail-type").textContent).toBe("Contract Call");
+    });
+});
+
 // Open the approval screen with Ethereum Mainnet active, for a site's Sepolia
 // transaction that sends SWAP_DATA to `sentTo`.
 async function showApprovalSentTo(sentTo) {

tests/unknownScaleSend.test.js

@@ -120,7 +120,7 @@ global.document = {
     body: { prepend() {}, appendChild() {} },
     addEventListener() {},
 };
-global.navigator = { clipboard: { writeText() {} } };
+global.navigator.clipboard = { writeText() {} };
 
 const { AbiCoder, parseUnits } = require("ethers");
 const { fetchTokenBalances } = require("../src/shared/balances");

tests/walletDefects.test.js

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