fix: the bundled token list names tokens on Ethereum Mainnet only (closes #632)

bundledToken(address, chainId) in tokenList.js answers only for Ethereum
Mainnet's chain id. Every reader of TOKEN_BY_ADDRESS now goes through it,
with the chain id of the transaction, balance or history entry it draws.
The token sources the screens build carry that chain id. The Uniswap
decoder sets the transaction's chain id on them. fetchTokenBalances()
takes the chain id of the network it asks about.

isSpoofedSymbol() takes the chain id of the token's network. It checks the
bundled list's symbols only on Ethereum Mainnet. The native asset's labels
stay reserved on every network.

Eighteen existing tests and three shared test helpers read the bundled
list without naming a network. Each now names Ethereum Mainnet.

Model: opus-5-5

README.md

@@ -1188,11 +1188,12 @@ The wallet takes the `decimals` from these sources, in this order
   "Use Blockscout" is on (`tokenSourcesByChainId()` in
   `src/popup/views/helpers.js`).
 
-The token's name comes from the same sources. While "Use Blockscout" is off, a
-token gets a line under it when the bundled list and the tracked tokens lack its
-name or decimals. The line says "Blockscout's report of your balances is not
-used to name this token, because "Use Blockscout" is off in Settings." These
-screens show the line:
+The token's name comes from the same sources. The bundled token list is used
+only for a token on Ethereum Mainnet. While "Use Blockscout" is off, a token
+gets a line under it when the bundled list and the tracked tokens lack its name
+or decimals. The line says "Blockscout's report of your balances is not used to
+name this token, because "Use Blockscout" is off in Settings." These screens
+show the line:
 
 - TxApproval and SignApproval
 - WaitTx, SuccessTx and ErrorTx, which follow TxApproval
@@ -1277,22 +1278,18 @@ see Transaction Decoding), do not always read as a number. They can read:
   step pays nothing itself and swaps whatever an earlier step sent to the pair,
   so the calldata states no quantity. A V3 exact-in `amountIn` of zero has no
   such meaning and is shown as a zero.
-- `None (no minimum guaranteed)`: the swap's `Min. received` line, when the
-  minimum it shows is zero, whether a V2, V3 or V4 swap's minimum or a
-  `BALANCE_CHECK_ERC20` step's `minBalance`. Before
-  [#359](https://git.eeqj.de/sneak/AutistMask/issues/359), a zero `minBalance`
-  read `0.0000` when the token's scale was known. The router passes a balance
-  check whenever the balance is at least `minBalance`, so a zero `minBalance`
-  guarantees nothing: it sets `Token Out` and `Min. received` only when the
-  output side holds no minimum, not even a zero one, at the point the check is
-  reached, and otherwise leaves the current token and figure in place. A nonzero
-  `minBalance` sets both lines, as a swap step does. Only a check of the
-  transaction's sender's own balance sets either line; a check of any other
-  address sets neither (see Transaction Decoding). A `BALANCE_CHECK_ERC20` step
-  that the router lets fail without reverting the transaction (see Transaction
-  Decoding) guarantees nothing either, whatever its `minBalance`, and is read as
-  one whose `minBalance` is zero. A minimum stated by a V4 swap step the router
-  lets fail is likewise read as zero.
+- `None (no minimum guaranteed)`: the swap's `Min. received` line, when it shows
+  a V2, V3 or V4 swap's minimum of zero. The router passes a
+  `BALANCE_CHECK_ERC20` step whenever the balance is at least `minBalance`, so a
+  zero `minBalance` guarantees nothing. A check with a zero `minBalance` sets
+  neither `Token Out` nor `Min. received`. A nonzero `minBalance` sets both
+  lines, as a swap step does. Only a check of the transaction's sender's own
+  balance sets either line; a check of any other address sets neither (see
+  Transaction Decoding). A `BALANCE_CHECK_ERC20` step that the router lets fail
+  without reverting the transaction (see Transaction Decoding) guarantees
+  nothing either, whatever its `minBalance`, and is read as one whose
+  `minBalance` is zero. A minimum stated by a V4 swap step the router lets fail
+  is likewise read as zero.
 
 The swap's `Token In` and `Token Out` lines name a currency, not an amount; each
 reads `Unknown (not named in the calldata)` when the decoder found no token for
@@ -1477,20 +1474,20 @@ tracked.
 
 A tracked token is shown when its balance is nonzero, and any other ERC-20 when
 its balance is nonzero and it is in the bundled known-token list or has 1,000 or
-more holders. A token claiming a symbol from the bundled list from any other
-contract address is always dropped, tracked or not, and so is any token claiming
-a symbol that belongs to the native asset and therefore has no legitimate
-contract at all (`"ETH"`, and every network's `nativeCurrency`, such as
-`"SepoliaETH"`, on every network). That filter is unconditional — the "Hide
-tokens with fewer than 1,000 holders" setting governs the transaction history
-and the send-screen token selector, not this list. A token's holder count is
-unknown when the explorer reports none, or reports anything other than a whole
-number written in digits alone, such as `1,000` or `1e3` (`parseHoldersCount()`
-in `src/shared/holders.js`). This list does not take an unknown count as 1,000
-or more, so such a token is shown only when it is on the bundled list or
-tracked. Every nonzero holding of a token shown is stored exactly, however
-small, but a holding below 0.000001 is left out of the balance lists, the
-send-screen token selector, the address total and the remove-address warning
+more holders. On Ethereum Mainnet, a token that claims a bundled token's symbol
+from another contract is always dropped, tracked or not. On every network, a
+token claiming a label of the native asset is always dropped. Those labels are
+`"ETH"` and each network's `nativeCurrency`, such as `"SepoliaETH"`. The balance
+list applies all three rules whatever the settings say. The "Hide tokens with
+fewer than 1,000 holders" setting governs only the transaction history and the
+send-screen token selector. A token's holder count is unknown when the explorer
+reports none, or reports anything other than a whole number written in digits
+alone, such as `1,000` or `1e3` (`parseHoldersCount()` in
+`src/shared/holders.js`). This list does not take an unknown count as 1,000 or
+more, so such a token is shown only when it is on the bundled list or tracked.
+Every nonzero holding of a token shown is stored exactly, however small, but a
+holding below 0.000001 is left out of the balance lists, the send-screen token
+selector, the address total and the remove-address warning
 (`isBelowOneMillionth()` in `src/shared/amountDisplay.js`). The Send and
 confirmation screens show it when its token is the one being sent. Tracked
 tokens with a zero balance are listed as well while "Show tracked tokens with
@@ -2281,6 +2278,11 @@ view would leave a wallet one click from deletion.
         - Endpoint URL input + "Save" button. "Save" asks the URL for `/stats`
           and saves the URL only if that request succeeds. The request carries
           no user data and is made whether or not "Use Blockscout" is ticked.
+    - If the network changes before either "Save" stores its URL, the URL is not
+      saved and a flash message says so
+    - Either "Save" stores its URL only if the input still shows that URL when
+      the endpoint answers. Otherwise a flash message says that the URL was not
+      saved
     - Etherscan:
         - "Check recipients on Etherscan" checkbox, unticked until the user
           ticks it
@@ -3197,26 +3199,25 @@ indexes it as a real token transfer.
   Ethereum mainnet ERC-20s taken from the CoinGecko API, with decimals verified
   on-chain and addresses EIP-55 checksummed; `TOKENS` in
   `src/shared/tokenList.js` is the authoritative set. It is bundled at build
-  time and only changes when that file is regenerated. Any token transfer
-  claiming a symbol from this list (e.g. "ETH", "USDT", "USDC") but originating
-  from an unrecognized contract address is identified as a spoof and filtered
-  from display. The fake "Ethereum" token in the attack above used symbol "ETH"
-  from contract `0xD05339f9Ea5ab9d9F03B9d57F671d2abD1F55c82`, which does not
-  match the known WETH contract — so it would be caught by this check. Detecting
-  a spoof is also what adds a contract to the fraud contract blocklist below;
-  that is the only thing that populates it. In the transaction history the check
-  is the "Hide fake tokens impersonating a known symbol" setting, on by default;
-  with it off, spoofed transfers are shown and no new blocklist entries are
-  learned from them. The send-screen token selector and the balance list apply
-  the same check unconditionally, because they decide which tokens the user can
-  act on and what the user believes they own rather than what the history
-  displays. All three surfaces read the rule from `src/shared/symbolSpoof.js`,
-  so they cannot answer the question differently. A symbol the list maps to no
-  contract at all — the native asset's labels: `"ETH"` and every network's
-  `nativeCurrency`, such as `"SepoliaETH"`, on every network — may be borne by
-  no contract, so every ERC-20 claiming it is a spoof on all three. The user's
-  real ETH balance is not an ERC-20 and is read over RPC, so the rule never sees
-  it.
+  time and only changes when that file is regenerated. On Ethereum Mainnet, a
+  token that claims a symbol from this list, such as "USDT" or "USDC", is a
+  spoof unless its contract is the listed one. The wallet hides it. The fake
+  "Ethereum" token in the attack above used symbol "ETH" from contract
+  `0xD05339f9Ea5ab9d9F03B9d57F671d2abD1F55c82`. No contract may bear "ETH", so
+  that token is a spoof. Detecting a spoof is also what adds a contract to the
+  fraud contract blocklist below; that is the only thing that populates it. In
+  the transaction history the check is the "Hide fake tokens impersonating a
+  known symbol" setting, on by default; with it off, spoofed transfers are shown
+  and no new blocklist entries are learned from them. The send-screen token
+  selector and the balance list apply the same check unconditionally, because
+  they decide which tokens the user can act on and what the user believes they
+  own rather than what the history displays. All three surfaces read the rule
+  from `src/shared/symbolSpoof.js`, so they cannot answer the question
+  differently. A symbol the list maps to no contract at all — the native asset's
+  labels: `"ETH"` and every network's `nativeCurrency`, such as `"SepoliaETH"`,
+  on every network — may be borne by no contract, so every ERC-20 claiming it is
+  a spoof on all three. The user's real ETH balance is not an ERC-20 and is read
+  over RPC, so the rule never sees it.
 
 - **Low-holder token filtering**: Token transfers from ERC-20 contracts with
   fewer than 1,000 holders are hidden from transaction history by default.
@@ -3395,7 +3396,8 @@ Currently supported:
   `Balance Check (of another address)`. A check whose input does not decode,
   such as one whose owner word has a nonzero top byte (the router reads the
   owner from the word's last 20 bytes), likewise sets neither, and it is listed
-  as `Balance Check (could not be decoded)`. When a swap step, `TAKE` or
+  as `Balance Check (could not be decoded)`. A check with a zero `minBalance`
+  sets neither `Token Out` nor the minimum. When a swap step, `TAKE` or
   `TAKE_PORTION` pays the router any token, the swap's output or another, a
   `WRAP_ETH` pays it WETH, or an `UNWRAP_WETH` into the router turns WETH a step
   paid it into ETH, that token stays in the router unless a later step pays out
@@ -3564,10 +3566,14 @@ Currently supported:
   on every router but `UniversalRouterV1`, and otherwise gives the address. A
   move into the router needs none of them, because its `Paid to` line and
   `Token moved into the router` line already give the amount, the token and
-  where it goes, and so its amount is shown once. Every `PERMIT2_PERMIT` whose
-  amount does not stand as the `Amount` figure, before the step that sets the
-  input side or after it, gives three lines, in step order, after those for each
-  `PERMIT2_TRANSFER_FROM`: `Permit2 allowance`, its amount, for example
+  where it goes, and so its amount is shown once. For a move of the zero
+  address, `Moved from the sender` gives the amount in base units and
+  `Token moved` gives the zero address. For such a move into the router, the
+  `Paid to` line gives the amount in base units and
+  `Token moved into the router` gives the zero address. Every `PERMIT2_PERMIT`
+  whose amount does not stand as the `Amount` figure, before the step that sets
+  the input side or after it, gives three lines, in step order, after those for
+  each `PERMIT2_TRANSFER_FROM`: `Permit2 allowance`, its amount, for example
   `5000.0000 DAI`, or `Unlimited` for Permit2's maximum; `Allowance token`,
   giving the token's address as the `Token In` line does; and
   `Allowance spender`, the address it lets take the token. Only a permit whose

docs/README.md

@@ -377,13 +377,15 @@ point-in-time snapshot of the highest-market-cap Ethereum mainnet ERC-20s, fixed
 at build time and updated only when a new release ships a newer snapshot. If a
 transaction or balance claims to involve a known symbol (like "ETH" or "USDT")
 but comes from an unrecognized contract, it is identified as a spoof and hidden.
-In your transaction history this is the "Hide fake tokens impersonating a known
-symbol" setting, which you can switch off; doing so also stops new entries being
-added to the fraud contract blocklist below, since detecting a spoof is what
-fills it. The send token list always applies the check. Your balances apply it
-too, with one exception: a token claiming the symbol "ETH" is not filtered
-there, so a fake "ETH" token can still show up in your balance list even though
-it is hidden from your transaction history and from the send token list.
+On Sepolia, only "ETH" and "SepoliaETH" count as known symbols, because the
+bundled list holds Ethereum Mainnet tokens. In your transaction history the
+check is the "Hide fake tokens impersonating a known symbol" setting, which you
+can switch off; doing so also stops new entries being added to the fraud
+contract blocklist below, since detecting a spoof is what fills it. The send
+token list always applies the check. Your balances apply it too, with one
+exception: a token claiming the symbol "ETH" is not filtered there, so a fake
+"ETH" token can still show up in your balance list even though it is hidden from
+your transaction history and from the send token list.
 
 **Low-holder token filtering.** Tokens with fewer than 1,000 holders are hidden
 from transaction history and the send token list, and are left out of your

src/popup/index.js

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

src/popup/views/addressToken.js

@@ -22,7 +22,7 @@ const {
     timeAgo,
 } = require("./helpers");
 const { state, saveState, currentNetwork } = require("../../shared/state");
-const { TOKEN_BY_ADDRESS, resolveSymbol } = require("../../shared/tokenList");
+const { bundledToken, resolveSymbol } = require("../../shared/tokenList");
 const { formatUsd, getPrice } = require("../../shared/prices");
 const {
     fetchRecentTransactions,
@@ -52,7 +52,8 @@ function show() {
 
     // Determine token symbol and balance
     let symbol, amount, price;
-    const knownToken = TOKEN_BY_ADDRESS.get(tokenId.toLowerCase());
+    const chainId = currentNetwork().chainId;
+    const knownToken = bundledToken(tokenId, chainId);
     if (tokenId === "ETH") {
         symbol = nativeCurrency();
         amount = parseFloat(addr.balance || "0");
@@ -65,6 +66,7 @@ function show() {
             tokenId,
             addr.tokenBalances,
             state.trackedTokens,
+            chainId,
         );
         // null when the scale is unknown: no quantity to show, and none to
         // price. balanceLine() states that rather than printing 0.0000.

src/popup/views/helpers.js

@@ -313,14 +313,17 @@ function nativeCurrency() {
 // The wallets' balances hold what Blockscout reported for each token. So the
 // wallets are returned only while "Use Blockscout" is on.
 function tokenSourcesByChainId(chainId) {
-    const net = chainId ? networkByChainId(chainId) : currentNetwork();
+    const chainIdOrActive = chainId || currentNetwork().chainId;
+    const net = networkByChainId(chainIdOrActive);
     if (net && net.id === state.networkId) {
         return {
+            chainId: chainIdOrActive,
             trackedTokens: state.trackedTokens,
             wallets: state.useBlockscout ? state.wallets : [],
         };
     }
     return {
+        chainId: chainIdOrActive,
         trackedTokens: (net && state.networkTrackedTokens[net.id]) || [],
         wallets: [],
     };
@@ -351,7 +354,7 @@ function blockscoutOffTokenNoteHtml(token, chainId) {
 
 // The symbol shown for a token line, from these sources in order:
 //
-// - the bundled list
+// - the bundled list, for a token on Ethereum Mainnet
 // - the tokens the user tracks
 // - the explorer's report, while "Use Blockscout" is on
 //

src/popup/views/send.js

@@ -12,7 +12,7 @@ const {
     goBack,
     tokenSourcesByChainId,
 } = require("./helpers");
-const { state, currentAddress } = require("../../shared/state");
+const { state, currentAddress, currentNetwork } = require("../../shared/state");
 let ctx;
 const { getProvider } = require("../../shared/balances");
 const { resolveTokenDecimals } = require("../../shared/approvalAmount");
@@ -154,7 +154,9 @@ function renderSendTokenSelect(addr) {
         // out. Its token's own screen can still send it: there
         // state.selectedToken picks the token, not this list.
         if (isBelowOneMillionth(t.balance)) continue;
-        if (isSpoofedSymbol(t.symbol, t.address)) continue;
+        if (isSpoofedSymbol(t.symbol, t.address, currentNetwork().chainId)) {
+            continue;
+        }
         if (fraudSet.has(t.address.toLowerCase())) continue;
         // An unknown holder count does not withhold a token the user holds:
         // only a count the explorer actually reported as below the threshold
@@ -230,6 +232,7 @@ function updateSendBalance() {
             token,
             addr.tokenBalances,
             state.trackedTokens,
+            currentNetwork().chainId,
         );
         // A null balance is a holding whose scale is unknown. Saying a figure
         // for it would be a claim about the amount, so it reads as the
@@ -385,6 +388,7 @@ function init(_ctx) {
                 token,
                 addr.tokenBalances,
                 state.trackedTokens,
+                currentNetwork().chainId,
             );
             ({ tokenDecimals } = tokenBalanceAndDecimals(addr, token));
         }

src/popup/views/settings.js

@@ -44,6 +44,12 @@ let ctx;
 let versionClickCount = 0;
 let versionClickTimer = null;
 
+// The network that Settings was last drawn for. A follow of a switch saved
+// elsewhere sets `state` to the new network first. Settings is drawn again only
+// once the follow's write returns. So both "Save" buttons take this network,
+// not the one in `state`.
+let shownNetwork = null;
+
 // One row per site origin, however many addresses it appears under, each with
 // an [x] that hands it to onRemove.
 function renderSiteList(containerId, origins, onRemove) {
@@ -199,6 +205,7 @@ function renderWalletListSettings() {
 }
 
 function show() {
+    shownNetwork = currentNetwork();
     $("settings-rpc").value = state.rpcUrl;
     $("settings-blockscout").value = state.blockscoutUrl;
     $("settings-network").value = state.networkId;
@@ -306,6 +313,7 @@ function showNewSettings() {
         state.checkRecipientsOnEtherscan;
     if (state.currentView === "settings") {
         markViewRendered("settings");
+        shownNetwork = currentNetwork();
         $("settings-network").value = state.networkId;
         $("settings-rpc").value = state.rpcUrl;
         $("settings-blockscout").value = state.blockscoutUrl;
@@ -319,6 +327,48 @@ function showNewSettings() {
     updateDebugBanner(state.currentView);
 }
 
+// Saves `url` as `field` ("rpcUrl" or "blockscoutUrl") of the network
+// `networkId`, the one that Settings showed when the user tapped "Save". The
+// URL is set in `state` inside the save, holding the lock. So the page cannot
+// follow a switch saved elsewhere (followStoredSettings() in
+// src/popup/index.js) between setting the URL and writing it. If the active
+// network is no longer `networkId`, on this page or in the stored record,
+// nothing is saved. The flash message then says that the network changed.
+//
+// The save writes only the fields that differ from what this page last saved.
+// Another page may have stored a different URL since then. So `url` is set in
+// the stored record too. "Saved." then means that the stored record holds
+// `url`.
+//
+// `input` is the id of the input that the user typed `url` in. When another
+// page changes the network, "Use Blockscout" or "Check recipients on
+// Etherscan", this page draws Settings again. A redraw during the endpoint
+// check puts the URL from `state` back in the input. So if the input no longer
+// shows `url`, nothing is saved. The flash message then says that the URL was
+// changed during the check. The save compares the input and sets `url` in
+// `state` in one step. So a redraw after the comparison shows `url`.
+async function saveEndpoint(field, input, url, networkId) {
+    let refused = false;
+    let inputChanged = false;
+    await saveState((stored) => {
+        refused =
+            state.networkId !== networkId || stored.networkId !== networkId;
+        inputChanged = $(input).value.trim() !== url;
+        if (refused || inputChanged) return false;
+        state[field] = url;
+        stored[field] = url;
+    });
+    if (refused) {
+        showFlash("The URL was not saved because the network changed.");
+    } else if (inputChanged) {
+        showFlash(
+            "The URL was not saved because it was changed during the check.",
+        );
+    } else {
+        showFlash("Saved.");
+    }
+}
+
 function init(_ctx) {
     ctx = _ctx;
     deleteWallet.init(ctx);
@@ -330,6 +380,8 @@ function init(_ctx) {
             showFlash("Please enter an RPC URL.");
             return;
         }
+        // The URL is for the network that Settings shows when "Save" is tapped.
+        const net = shownNetwork;
         showFlash("Testing endpoint...");
         try {
             const resp = await debugFetch(url, {
@@ -348,7 +400,6 @@ function init(_ctx) {
                 showFlash("Endpoint returned an error.");
                 return;
             }
-            const net = currentNetwork();
             if (json.result !== net.chainId) {
                 showFlash("Wrong network: expected " + net.name + ".");
                 return;
@@ -364,9 +415,7 @@ function init(_ctx) {
             showFlash("Could not reach endpoint.");
             return;
         }
-        state.rpcUrl = url;
-        await saveState();
-        showFlash("Saved.");
+        await saveEndpoint("rpcUrl", "settings-rpc", url, net.id);
     });
 
     $("btn-save-blockscout").addEventListener("click", async () => {
@@ -375,6 +424,7 @@ function init(_ctx) {
             showFlash("Please enter a Blockscout API URL.");
             return;
         }
+        const net = shownNetwork;
         showFlash("Testing endpoint...");
         try {
             const resp = await debugFetch(url + "/stats");
@@ -389,9 +439,7 @@ function init(_ctx) {
             showFlash("Could not reach endpoint.");
             return;
         }
-        state.blockscoutUrl = url;
-        await saveState();
-        showFlash("Saved.");
+        await saveEndpoint("blockscoutUrl", "settings-blockscout", url, net.id);
     });
 
     // Each change is made inside the save, holding the lock. So

src/popup/views/transactionDetail.js

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

src/shared/approvalAmount.js

@@ -29,7 +29,7 @@
 // string, and a token the user added by hand carries whatever lookupTokenInfo()
 // got back, so the accepted types are enumerated rather than coerced.
 const { toDecimals } = require("./transferAmount");
-const { TOKEN_BY_ADDRESS } = require("./tokenList");
+const { bundledToken } = require("./tokenList");
 const { isSpoofedSymbol } = require("./symbolSpoof");
 
 // Every decimals the explorer reported for this contract, across all the
@@ -53,12 +53,14 @@ function explorerDecimals(lower, wallets) {
 }
 
 // The decimals to render a token amount with, or null when nothing knows.
-// `sources` is { trackedTokens, wallets }, both shaped as they are on `state`.
+// `sources` is { chainId, trackedTokens, wallets }. `chainId` is the chain id
+// of the token's network. The bundled list is read only when that network is
+// Ethereum Mainnet. `trackedTokens` and `wallets` are shaped as on `state`.
 function resolveTokenDecimals(tokenAddress, sources) {
     const lower = (tokenAddress || "").toLowerCase();
     if (!lower) return null;
 
-    const bundled = TOKEN_BY_ADDRESS.get(lower);
+    const bundled = bundledToken(lower, sources && sources.chainId);
     if (bundled) {
         const d = toDecimals(bundled.decimals);
         if (d !== null) return d;
@@ -100,18 +102,19 @@ function explorerSymbol(lower, wallets) {
 // explorer reported: the same sources and the same precedence
 // resolveTokenDecimals() uses, so a token's name and its scale are drawn from
 // the same place and the two can no longer disagree about which sources they
-// trust. `sources` is { trackedTokens, wallets }, shaped as on `state`.
+// trust. `sources` is as for resolveTokenDecimals().
 //
 // A tracked or explorer-reported symbol is attacker-influenced text, so it is
-// held to the spoof rule (symbolSpoof.js): a candidate that wears a bundled or
-// native ticker from a contract not entitled to it is refused and the next
-// source tried, so resolving a symbol never becomes a new way to claim a known
-// ticker. The bundled list is the wallet's own data and is trusted as it is.
+// held to the spoof rule (symbolSpoof.js): a candidate that the rule calls a
+// spoof is refused and the next source tried, so resolving a symbol never
+// becomes a new way to claim a known ticker. The bundled list is the wallet's
+// own data and is trusted as it is.
 function resolveTokenSymbol(tokenAddress, sources) {
     const lower = (tokenAddress || "").toLowerCase();
     if (!lower) return null;
 
-    const bundled = TOKEN_BY_ADDRESS.get(lower);
+    const chainId = sources && sources.chainId;
+    const bundled = bundledToken(lower, chainId);
     if (bundled && bundled.symbol) return bundled.symbol;
 
     const tracked = ((sources && sources.trackedTokens) || []).find(
@@ -123,7 +126,7 @@ function resolveTokenSymbol(tokenAddress, sources) {
     if (reported) candidates.push(reported);
 
     for (const symbol of candidates) {
-        if (!isSpoofedSymbol(symbol, tokenAddress)) return symbol;
+        if (!isSpoofedSymbol(symbol, tokenAddress, chainId)) return symbol;
     }
     return null;
 }

src/shared/balances.js

@@ -17,7 +17,7 @@ const { ERC20_ABI } = require("./constants");
 const { NETWORKS } = require("./networks");
 const { log, debugFetch, urlOrigin } = require("./log");
 const { deriveAddressFromXpub } = require("./wallet");
-const { TOKEN_BY_ADDRESS } = require("./tokenList");
+const { bundledToken } = require("./tokenList");
 const { LOW_HOLDER_THRESHOLD, parseHoldersCount } = require("./holders");
 const { isSpoofedSymbol } = require("./symbolSpoof");
 const { toDecimals } = require("./transferAmount");
@@ -106,6 +106,9 @@ function rawUnits(value) {
 // balance is read through the RPC endpoint instead, and its row here gives that
 // entry its holder count and `decimals` (fetchTrackedTokenBalances()).
 //
+// `chainId` is the chain id of the network `blockscoutUrl` serves. The known
+// token list is used only when that network is Ethereum Mainnet.
+//
 // `decimals` and `balance` are each null when the answer is unknown, the same
 // way `holders` already is. Absence is never filled in here: this is the
 // upstream of every screen that displays a token amount, so a value invented
@@ -117,6 +120,7 @@ async function fetchTokenBalances(
     address,
     blockscoutUrl,
     trackedTokens,
+    chainId,
     signal,
 ) {
     if (!(await storedSettingIsOn("useBlockscout"))) return [];
@@ -175,7 +179,10 @@ async function fetchTokenBalances(
             // either way: copying another source into it would make
             // explorerDecimals()'s disagreement check compare something other
             // than explorer values.
-            const known = resolveTokenDecimals(tokenAddr, { trackedTokens });
+            const known = resolveTokenDecimals(tokenAddr, {
+                chainId,
+                trackedTokens,
+            });
             const scale = known !== null ? known : decimals;
             // null is a holding of an amount that cannot be stated, which is
             // not the same as a holding of zero, and must never render as one.
@@ -191,7 +198,7 @@ async function fetchTokenBalances(
             // through to the views, where the two low-holder filters treat
             // an unknown count as "do not judge" rather than as zero.
             const holders = parseHoldersCount(item.token.holders_count);
-            const isKnown = TOKEN_BY_ADDRESS.has(tokenAddr);
+            const isKnown = bundledToken(tokenAddr, chainId) !== null;
             const isTracked = trackedSet.has(tokenAddr);
             const hasEnoughHolders = holders >= LOW_HOLDER_THRESHOLD;
 
@@ -202,7 +209,9 @@ async function fetchTokenBalances(
             // Every row here is an ERC-20 the explorer reported, so it has a
             // contract address; the native ETH balance is fetched over RPC in
             // refreshBalances and never passes through this loop.
-            if (isSpoofedSymbol(item.token.symbol, tokenAddr)) continue;
+            if (isSpoofedSymbol(item.token.symbol, tokenAddr, chainId)) {
+                continue;
+            }
 
             balances.push({
                 address: item.token.address_hash,
@@ -249,17 +258,18 @@ async function fetchTokenBalances(
 // zero from the tracked list. A token whose symbol the spoof rule refuses gets
 // no entry either, as in fetchTokenBalances().
 //
-// `signal` is as for fetchTokenBalances().
+// `chainId` and `signal` are as for fetchTokenBalances().
 async function fetchTrackedTokenBalances(
     provider,
     address,
     trackedTokens,
     previous,
     explorerRequest,
+    chainId,
     signal,
 ) {
     const listed = trackedTokens.filter(
-        (token) => !isSpoofedSymbol(token.symbol, token.address),
+        (token) => !isSpoofedSymbol(token.symbol, token.address, chainId),
     );
     // Each token's balanceOf answer, or null where it failed.
     const balances = await Promise.all(
@@ -301,7 +311,7 @@ async function fetchTrackedTokenBalances(
         if (raw === 0n) return;
         const entry = entryIn(reported);
         const decimals = entry ? entry.decimals : null;
-        const known = resolveTokenDecimals(lower, { trackedTokens });
+        const known = resolveTokenDecimals(lower, { chainId, trackedTokens });
         const scale = known !== null ? known : decimals;
         rows.push({
             address: token.address,
@@ -330,6 +340,7 @@ async function refreshBalances(
 ) {
     log.debugf("refreshBalances start, rpc:", urlOrigin(rpcUrl));
     const provider = getProvider(rpcUrl, networkId);
+    const { chainId } = requireNetworkId(networkId);
     const tracked = trackedTokens || [];
     const trackedSet = new Set(tracked.map((t) => t.address.toLowerCase()));
     const updates = [];
@@ -393,6 +404,7 @@ async function refreshBalances(
                 addr.address,
                 blockscoutUrl,
                 tracked,
+                chainId,
                 signal,
             );
             updates.push(
@@ -403,6 +415,7 @@ async function refreshBalances(
                         tracked,
                         previous,
                         explorerRequest,
+                        chainId,
                         signal,
                     ),
                     explorerRequest,

src/shared/chainSwitch.js

@@ -47,12 +47,43 @@ function clearPopupCaches() {
 // lock, so it is never switched while a follow of a switch saved elsewhere
 // waits for the lock (followStoredSettings() in src/popup/index.js): that
 // follow runs first, and this switch is made after it.
+//
+// The save writes only the fields that differ from what this page last saved.
+// When this page last saved a balance of "0", clearing that balance is no
+// change. So the switch also resets these fields in the stored record:
+//
+// - every address's balance and token balances;
+// - the time of the last balance refresh;
+// - the fraud contracts.
+//
+// A balance or a fraud contract that the background or another page stored
+// since this page's last save is then not kept under the new network
+// (https://git.eeqj.de/sneak/AutistMask/issues/653,
+// https://git.eeqj.de/sneak/AutistMask/issues/692).
+//
+// Before the switch, `state` takes the tracked tokens that another page stored
+// since this page's last save (takeStoredTrackedTokens() in state.js). The
+// switch then puts them away under the previous network, the network they were
+// added on. When the stored record is on another network, a switch saved
+// elsewhere has not reached this page yet. The stored record's tokens are then
+// that network's, and none are taken.
 async function onChainSwitch(newNetworkId) {
-    const { state, saveState } = require("./state");
+    const { state, saveState, takeStoredTrackedTokens } = require("./state");
     let net = null;
-    await saveState(() => {
+    await saveState((stored) => {
         if (state.networkId === newNetworkId) return false;
+        if (stored.networkId === state.networkId) {
+            takeStoredTrackedTokens(stored);
+        }
         net = applyChainSwitchFields(state, newNetworkId);
+        stored.lastBalanceRefresh = 0;
+        stored.fraudContracts = [];
+        for (const wallet of stored.wallets) {
+            for (const addr of wallet.addresses) {
+                addr.balance = "0";
+                addr.tokenBalances = [];
+            }
+        }
         clearPopupCaches();
     });
     return net;

src/shared/state.js

@@ -125,11 +125,12 @@ function currentNetwork() {
     return networkById(state.networkId);
 }
 
-// The persisted fields as this page held them when its last loadState()
-// finished, or when its last successful saveState() began, with any network
-// switch saved elsewhere that this page has taken since (takeStoredNetwork()).
-// saveState() diffs the live state against this to find only the fields THIS
-// page changed since.
+// `baseline` holds the persisted fields as this page held them when its last
+// loadState() finished, or when its last successful saveState() began.
+// takeStoredNetwork() and takeStoredTrackedTokens() also write into it what
+// this page has taken from the stored record since then. saveState() diffs the
+// live state against `baseline` to find only the fields THIS page changed
+// since.
 //
 // Deep-cloned, not a reference: callers mutate persisted objects and arrays
 // in place (state.wallets.push(...)), and a reference baseline would mutate
@@ -442,8 +443,10 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 // milder than the other two.
 //
 // Every other persisted field stays a whole-field diff:
-// `trackedTokens`/`fraudContracts`/`viewStack` are arrays of scalars with no
-// per-element identity to merge by; `networkTrackedTokens` is diffed whole like
+// `fraudContracts`/`viewStack` are arrays of scalars with no per-element
+// identity to merge by; a save diffs `trackedTokens` whole, and a switch in
+// Settings first merges that list by contract address
+// (takeStoredTrackedTokens()); `networkTrackedTokens` is diffed whole like
 // `trackedTokens` and `networkId`, the two fields a network switch moves
 // together with it; `tokenHolderCache` is a map shaped like the ones above,
 // but nothing in src/ ever writes an entry into it — it is only ever reset
@@ -591,8 +594,10 @@ function reportSaveFailure(err) {
 //
 // `beforeWrite`, when given, is called inside the lock with the stored record
 // as just read, before this page's state is compared against it. It may change
-// `state`, and this save writes that change. When it returns false, nothing is
-// written; any other return lets the save go ahead.
+// `state`, and this save writes that change. It may also change the stored
+// record. A field that this page did not change is then written as
+// `beforeWrite` left it. When it returns false, nothing is written; any other
+// return lets the save go ahead.
 function saveState(beforeWrite) {
     const turn = withLock("autistmask", () => saveStateOnce(beforeWrite));
     // Every failed save is reported, whether or not the caller awaited this
@@ -613,6 +618,28 @@ function takeStoredNetwork(stored) {
     copyChainSwitchFields(baseline, structuredClone(stored));
 }
 
+// Give this page the tracked tokens of `stored`, a record on this page's
+// network that a save of this page has just read (onChainSwitch() in
+// src/shared/chainSwitch.js calls this from `beforeWrite`):
+//
+// - A token that another page tracked or removed since this page's last save
+//   is tracked or removed in `state` too.
+// - A token that this page tracked or removed since then stays as this page
+//   has it.
+//
+// `baseline` takes the stored list, so the save stores the list in `state`
+// whenever the two differ.
+function takeStoredTrackedTokens(stored) {
+    rawState.trackedTokens = mergeListByIdentity(
+        baseline.trackedTokens,
+        rawState.trackedTokens,
+        stored.trackedTokens,
+        (token) => token.address.toLowerCase(),
+        (base, ours) => ours,
+    );
+    baseline.trackedTokens = structuredClone(stored.trackedTokens);
+}
+
 // Rejects with StateUnusableError for a stored record this build cannot make
 // sense of. Nothing is assigned and `loaded` stays false in that case, so a
 // caller that ignores the rejection gets StateNotLoadedError on the first
@@ -659,6 +686,7 @@ module.exports = {
     saveState,
     onSaveFailure,
     takeStoredNetwork,
+    takeStoredTrackedTokens,
     loadState,
     currentAddress,
     currentNetwork,

src/shared/symbolSpoof.js

@@ -19,7 +19,8 @@
 // them hid the other one's holders' money (issue #276).  Membership, not
 // equality, is therefore the question — but it is the same question, asked of
 // a table that can now state the truth.  Every address in a set is one the
-// wallet ships as a real token; a contract outside the set is still a spoof.
+// wallet ships as a real token on Ethereum Mainnet.  On mainnet, a contract
+// outside the set is still a spoof.
 //
 // The symbol is attacker-controlled — it is whatever the ERC-20 contract
 // returns — so the lookup is done on a normalized form (issue #260): the
@@ -27,6 +28,7 @@
 // since that is what the user acts on.
 
 const { KNOWN_SYMBOLS } = require("./tokenList");
+const { NETWORKS } = require("./networks");
 
 // Ethereum addresses are case-insensitive: EIP-55 mixed case is a checksum
 // over the address, not part of its identity.
@@ -93,18 +95,24 @@ function normalizeSymbol(symbol) {
 }
 
 // True when a token bearing `symbol` from contract `contractAddress` is
-// impersonating a known symbol.
+// impersonating a known symbol. `chainId` is the chain id of the token's
+// network.
+//
+// The native asset's labels are known symbols on every network. The bundled
+// list's symbols are known symbols only on Ethereum Mainnet, because the list
+// holds mainnet contracts.
 //
 // An empty contract address is the native asset, which is never a spoof:
 // this is what keeps the user's real ETH out of the rule, and it holds for
 // any symbol that becomes null-mapped later, not just for ETH.
-function isSpoofedSymbol(symbol, contractAddress) {
+function isSpoofedSymbol(symbol, contractAddress, chainId) {
     const contract = normalizeAddress(contractAddress);
     if (!contract) return false;
     const sym = normalizeSymbol(symbol);
     if (!KNOWN_SYMBOLS.has(sym)) return false;
     const legit = KNOWN_SYMBOLS.get(sym);
     if (legit === null) return true;
+    if (chainId !== NETWORKS.mainnet.chainId) return false;
     return !legit.has(contract);
 }
 

src/shared/tokenList.js

@@ -3953,6 +3953,15 @@ for (const t of TOKENS) {
     TOKEN_BY_ADDRESS.set(t.address.toLowerCase(), t);
 }
 
+// The bundled list's entry for the contract at `address` on the network with
+// chain id `chainId`, or null. The list holds Ethereum Mainnet contracts only.
+// A contract at the same address on another network is another token, so any
+// other chain id gets null.
+function bundledToken(address, chainId) {
+    if (chainId !== NETWORKS.mainnet.chainId) return null;
+    return TOKEN_BY_ADDRESS.get((address || "").toLowerCase()) || null;
+}
+
 // Build a map of symbol (uppercased) -> the set of contract addresses
 // (lowercased) that legitimately bear it.  Used for spoofed-symbol detection.
 // "ETH" maps to null: the native asset has no contract, so no contract may
@@ -3969,7 +3978,8 @@ for (const t of TOKENS) {
 // hides from the balance list, the history and the send selector at its own
 // address, so the user cannot spend it (issue #276).  Naming every address
 // that bears the symbol is the only shape that says what is true; it does not
-// loosen the rule, because a contract outside the set is still a spoof.
+// loosen the rule.  On Ethereum Mainnet, a contract outside the set is still a
+// spoof.
 const KNOWN_SYMBOLS = new Map();
 KNOWN_SYMBOLS.set("ETH", null);
 for (const network of Object.values(NETWORKS)) {
@@ -3988,14 +3998,15 @@ for (const t of TOKENS) {
     }
 }
 
-// Resolve a token symbol from multiple sources, never returning "?".
-function resolveSymbol(tokenAddress, tokenBalances, trackedTokens) {
+// Resolve a token symbol from multiple sources, never returning "?". The token
+// is a contract on the network with chain id `chainId`.
+function resolveSymbol(tokenAddress, tokenBalances, trackedTokens, chainId) {
     const lower = (tokenAddress || "").toLowerCase();
     const tb = (tokenBalances || []).find(
         (t) => t.address.toLowerCase() === lower,
     );
     if (tb && tb.symbol) return tb.symbol;
-    const known = TOKEN_BY_ADDRESS.get(lower);
+    const known = bundledToken(lower, chainId);
     if (known && known.symbol) return known.symbol;
     const tracked = (trackedTokens || []).find(
         (t) => t.address.toLowerCase() === lower,
@@ -4012,5 +4023,6 @@ module.exports = {
     USD_PRICE_FEEDS,
     PRICE_FEED_BY_ADDRESS,
     getTopTokens,
+    bundledToken,
     resolveSymbol,
 };

src/shared/transactions.js

@@ -8,7 +8,7 @@
 
 const { formatEther, formatUnits } = require("ethers");
 const { log, debugFetch } = require("./log");
-const { TOKEN_BY_ADDRESS } = require("./tokenList");
+const { bundledToken } = require("./tokenList");
 const { parseHoldersCount, isLowHolderCount } = require("./holders");
 const { isSpoofedSymbol } = require("./symbolSpoof");
 const { nativeCurrencyByChainId } = require("./networks");
@@ -47,7 +47,7 @@ function parseTx(tx, addrLower, chainId) {
     let direction = normalizeAddress(from) === addrLower ? "sent" : "received";
     let directionLabel = direction === "sent" ? "Sent" : "Received";
     if (toIsContract && method && method !== "transfer") {
-        const token = TOKEN_BY_ADDRESS.get(normalizeAddress(to));
+        const token = bundledToken(to, chainId);
         if (token) {
             symbol = token.symbol;
         }
@@ -317,7 +317,10 @@ function filterTransactions(txs, filters = {}) {
         const contract = normalizeAddress(tx.contractAddress);
 
         // Filter spoofed known symbols and record the fraud contract
-        if (hideSpoofed && isSpoofedSymbol(tx.symbol, tx.contractAddress)) {
+        if (
+            hideSpoofed &&
+            isSpoofedSymbol(tx.symbol, tx.contractAddress, tx.chainId)
+        ) {
             if (contract && !fraudSet.has(contract)) {
                 fraudSet.add(contract);
                 newFraud.push(contract);

src/shared/uniswap.js

@@ -452,8 +452,8 @@ const ADDRESS_THIS = "0x0000000000000000000000000000000000000002";
 // `decimals` is null when nothing knows this token's scale. It is not
 // defaulted to 18: the swap lines land on the same approval screen as the
 // ERC-20 line, and a scale guessed there is what showed a 1,000 USDT swap as
-// 0.000000000001. `sources` is { trackedTokens, wallets }, shaped as they are
-// on `state`; resolveTokenDecimals() reads the bundled list, then those.
+// 0.000000000001. `sources` is as for resolveTokenDecimals(), which reads the
+// bundled list on Ethereum Mainnet, then the tracked tokens and the wallets.
 //
 // A null `address` means UNDETERMINED — the calldata named no currency for
 // that side — and is refused rather than named. It is not native ETH: Uniswap
@@ -479,6 +479,17 @@ function tokenInfo(address, sources) {
     };
 }
 
+// The token of a Permit2 allowance or of a PERMIT2_TRANSFER_FROM, in the
+// shape tokenInfo() gives. Permit2 has no allowance of ETH and moves no ETH.
+// The zero address there reads as a token nothing knows: its amount in base
+// units, and the zero address as its token.
+function permit2TokenInfo(address, sources) {
+    if (address === "0x0000000000000000000000000000000000000000") {
+        return { symbol: null, decimals: null, address };
+    }
+    return tokenInfo(address, sources);
+}
+
 // A swap amount line. With a scale it is the token quantity; with none it is
 // the base-unit integer with the unknown scale stated, the same refusal the
 // ERC-20 amount line makes, so the screen has one way of saying it. `display`
@@ -497,16 +508,18 @@ function amountText(raw, info) {
 
 // The line giving a moved token, or the token of a permit, under `label`, in
 // the shape of the Token In line, so the screens show it as they show that
-// one. ETH has no address.
-function tokenMovedLine(label, token, sources) {
-    const info = tokenInfo(token, sources);
+// one. `info` is what tokenInfo() or permit2TokenInfo() gives for the token.
+// ETH has no address.
+function tokenMovedLine(label, info) {
     if (!present(info.address)) {
         return { label, value: info.symbol };
     }
     return {
         label,
-        value: info.symbol ? info.symbol + " (" + token + ")" : token,
-        address: token,
+        value: info.symbol
+            ? info.symbol + " (" + info.address + ")"
+            : info.address,
+        address: info.address,
         isToken: true,
     };
 }
@@ -1227,6 +1240,9 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
     const release = routerRelease(toAddress, chainId);
     if (release === null) return null;
     const { commandTypeMask, commands, allowRevert } = release;
+    // The swap's tokens are contracts on the network with `chainId`, so they
+    // are named and scaled for that network.
+    const tokenSources = { ...sources, chainId };
     try {
         const parsed = ROUTER_IFACE.parseTransaction({ data });
         if (!parsed) return null;
@@ -1616,13 +1632,13 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     } else {
                         // The router passes this check whenever the owner
                         // holds at least minBalance, so a zero one guarantees
-                        // nothing and does not replace a minimum an earlier
-                        // step stated. A check the router lets fail guarantees
-                        // nothing either, so it is read as a zero one. Any
+                        // nothing. A check the router lets fail guarantees
+                        // nothing either, so it is read as a zero one. A zero
+                        // check sets neither Token Out nor the minimum. Any
                         // other minBalance sets the output side as a swap
-                        // does. It pays nobody.
+                        // does. The check pays nobody.
                         const minBalance = allowedToFail ? 0n : b.minBalance;
-                        if (!(minBalance === 0n && present(minOutput))) {
+                        if (minBalance !== 0n) {
                             setOutput(i, b.token, minBalance, []);
                         }
                         keepsRouterWeth = true;
@@ -2195,11 +2211,11 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // 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 inInfo = tokenInfo(inputToken, tokenSources);
         const outInfo =
             outputUnwrapped || (hasUnwrapWeth && !outputEstablished)
                 ? { symbol: "ETH", decimals: 18, address: null }
-                : tokenInfo(outputToken, sources);
+                : tokenInfo(outputToken, tokenSources);
 
         const inSymbol = inInfo.symbol;
         const outSymbol = outInfo.symbol;
@@ -2324,12 +2340,20 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             details.push({
                 label: "Moved from the sender",
                 value: present(s.amount)
-                    ? spentText(s.amount, tokenInfo(s.token, sources), s.atMost)
-                          .display
+                    ? spentText(
+                          s.amount,
+                          tokenInfo(s.token, tokenSources),
+                          s.atMost,
+                      ).display
                     : UNDECODED_CURRENCY,
             });
             if (present(s.token)) {
-                details.push(tokenMovedLine("Token moved", s.token, sources));
+                details.push(
+                    tokenMovedLine(
+                        "Token moved",
+                        tokenInfo(s.token, tokenSources),
+                    ),
+                );
                 details.push({
                     label: "Moved to",
                     value: "The swap step that spends it",
@@ -2340,12 +2364,12 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // What each PERMIT2_TRANSFER_FROM moves: its amount, its token and
         // where it goes, an address on a line of its own.
         for (const m of movedFromSender) {
+            const info = permit2TokenInfo(m.token, tokenSources);
             details.push({
                 label: "Moved from the sender",
-                value: amountText(m.amount, tokenInfo(m.token, sources))
-                    .display,
+                value: amountText(m.amount, info).display,
             });
-            details.push(tokenMovedLine("Token moved", m.token, sources));
+            details.push(tokenMovedLine("Token moved", info));
             details.push(
                 present(m.to)
                     ? { label: "Moved to", value: m.to }
@@ -2375,36 +2399,15 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                 });
                 continue;
             }
-            // Permit2 has no allowance of ETH. An allowance of the zero
-            // address reads as one of a token nothing knows: its amount in
-            // base units, and the zero address as its token.
-            if (p.token === "0x0000000000000000000000000000000000000000") {
-                details.push({
-                    label: "Permit2 allowance",
-                    value:
-                        p.amount >= MAX_UINT160
-                            ? "Unlimited"
-                            : unknownDecimalsAmount(p.amount),
-                });
-                details.push({
-                    label: "Allowance token",
-                    value: p.token,
-                    address: p.token,
-                    isToken: true,
-                });
-            } else {
-                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),
-                );
-            }
+            const info = permit2TokenInfo(p.token, tokenSources);
+            details.push({
+                label: "Permit2 allowance",
+                value:
+                    p.amount >= MAX_UINT160
+                        ? "Unlimited"
+                        : amountText(p.amount, info).display,
+            });
+            details.push(tokenMovedLine("Allowance token", info));
             details.push({
                 label: "Allowance spender",
                 value: p.spender,
@@ -2462,7 +2465,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             paidTo.push({ label: "Paid to", value: PAID_TO_BRIDGE });
         }
         for (const m of movedIntoRouter) {
-            const info = tokenInfo(m.token, sources);
+            const info = permit2TokenInfo(m.token, tokenSources);
             paidTo.push({
                 label: "Paid to",
                 value:
@@ -2470,9 +2473,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     amountText(m.amount, info).display +
                     " from the sender (later steps may not spend all of it)",
             });
-            paidTo.push(
-                tokenMovedLine("Token moved into the router", m.token, sources),
-            );
+            paidTo.push(tokenMovedLine("Token moved into the router", info));
         }
         if (outputHeld) {
             paidTo.push({ label: "Paid to", value: STAYS_IN_ROUTER });
@@ -2489,8 +2490,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             paidTo.push(
                 tokenMovedLine(
                     "Token moved into the router",
-                    getAddress(token),
-                    sources,
+                    tokenInfo(getAddress(token), tokenSources),
                 ),
             );
         }

tests/approvalAmount.test.js

@@ -90,9 +90,11 @@ beforeEach(() => {
 });
 
 describe("resolveTokenDecimals", () => {
+    // The bundled list is read only for a token on Ethereum Mainnet.
     test("prefers the bundled list", () => {
         state.trackedTokens = [{ address: USDC, symbol: "USDC", decimals: 2 }];
-        expect(resolveTokenDecimals(USDC, state)).toBe(6);
+        const sources = { chainId: "0x1", trackedTokens: state.trackedTokens };
+        expect(resolveTokenDecimals(USDC, sources)).toBe(6);
     });
 
     test("reads a token the user tracks", () => {
@@ -124,7 +126,8 @@ describe("resolveTokenDecimals", () => {
     // answers 0 is used rather than fallen past like the unusable entry above.
     test("uses a bundled scale of zero", () => {
         state.trackedTokens = [{ address: SLP, symbol: "SLP", decimals: 18 }];
-        expect(resolveTokenDecimals(SLP, state)).toBe(0);
+        const sources = { chainId: "0x1", trackedTokens: state.trackedTokens };
+        expect(resolveTokenDecimals(SLP, sources)).toBe(0);
     });
 
     test("uses a tracked scale of zero", () => {

tests/approvalBundledListSepolia.test.js

@@ -0,0 +1,169 @@
+// The approval screen for a site's Sepolia transfer of the contract at USDC's
+// mainnet address, while Sepolia is active.
+//
+// The bundled token list holds Ethereum Mainnet contracts. The contract at the
+// same address on Sepolia is another token, but the screen named it USDC and
+// scaled its amount at USDC's decimals
+// (https://git.eeqj.de/sneak/AutistMask/issues/632). The bundled list now names
+// a token only on Ethereum Mainnet. The same screen for a mainnet transfer of
+// USDC, while Sepolia is active, still names USDC.
+//
+// Driven through the real approval screen, against the minimal DOM stub
+// tests/approvalTokenNetwork.test.js uses.
+
+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 approval = require("../src/popup/views/approval");
+
+const FROM = "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266";
+const RECIPIENT = "0x711e691962E5c054b78071C789A0C8CE657377aD";
+// USDC's address on Ethereum Mainnet, where the bundled list names it.
+const USDC = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
+
+// FROM sends 1234500000 base units 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);
+}
+
+// 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 Sepolia active, for the site's transaction
+// sending TRANSFER_DATA to the contract at USDC's address on the network with
+// chain id `chainId`.
+async function showTransfer(chainId) {
+    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: "0x30d40",
+                    maxPriorityFeePerGas: "0x3b9aca00",
+                    maxFeePerGas: "0x77359400",
+                    to: USDC,
+                    value: "0x0",
+                    data: TRANSFER_DATA,
+                    accessList: [],
+                },
+            });
+        },
+    };
+    state.networkId = "sepolia";
+    state.trackedTokens = [];
+    state.networkTrackedTokens = {};
+    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;
+    approval.init({});
+    await approval.show(1);
+}
+
+test("names no token, and states the amount in base units", async () => {
+    await showTransfer(NETWORKS.sepolia.chainId);
+    expect(state.currentView).toBe("approve-tx");
+    expect(node("approve-tx-to").innerHTML).not.toContain("USDC");
+    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>',
+    );
+});
+
+// A transaction is named for its own network, not the active one.
+test("a mainnet transfer of USDC is still named and scaled as USDC", async () => {
+    await showTransfer(NETWORKS.mainnet.chainId);
+    expect(state.currentView).toBe("approve-tx");
+    expect(decodedLine("Token")).toContain('<div class="font-bold">USDC</div>');
+    expect(decodedLine("Amount")).toContain(
+        '<div class="font-bold">1234.5000 USDC</div>',
+    );
+});

tests/balanceRefreshNetworkSwitch.test.js

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

tests/bundledListScreens.test.js

@@ -0,0 +1,81 @@
+// The token screen, the Send screen and the confirmation screen for the
+// contract at USDC's mainnet address. No address holds it and the user does
+// not track it, so only the bundled token list can name it.
+//
+// The bundled token list holds Ethereum Mainnet contracts, so these screens
+// name the token from it on Ethereum Mainnet only
+// (https://git.eeqj.de/sneak/AutistMask/issues/632). Driven through the real
+// popup over a stored profile.
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+} = require("./support/popupBoot");
+
+const USDC = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
+const RECIPIENT = "0x711e691962E5c054b78071C789A0C8CE657377aD";
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+// The popup reopened onto AddressToken for USDC's address, on `networkId`.
+function bootOnToken(networkId) {
+    return bootPopup(
+        unversionedValidProfile({
+            networkId,
+            currentView: "address-token",
+            viewStack: ["main", "address"],
+            selectedWallet: 0,
+            selectedAddress: 0,
+            selectedToken: USDC,
+        }),
+    );
+}
+
+// AddressToken's Send, then Review for 1 token to RECIPIENT.
+async function reviewSend(boot) {
+    await boot.click("btn-address-token-send");
+    expect(boot.visibleViews()).toEqual(["send"]);
+    boot.node("send-to").value = RECIPIENT;
+    boot.node("send-amount").value = "1";
+    await boot.click("btn-send-review");
+    expect(boot.visibleViews()).toEqual(["confirm-tx"]);
+}
+
+describe("on Ethereum Mainnet, the bundled list names the token", () => {
+    test("on the token screen", async () => {
+        const boot = await bootOnToken("mainnet");
+        expect(boot.visibleViews()).toEqual(["address-token"]);
+        expect(boot.text("address-token-title")).toContain("USDC");
+        const info = boot.node("address-token-contract-info").innerHTML;
+        expect(info).toContain(
+            '<span class="text-muted">Decimals:</span> 6</div>',
+        );
+    });
+
+    test("on the Send screen and the confirmation screen", async () => {
+        const boot = await bootOnToken("mainnet");
+        await reviewSend(boot);
+        expect(boot.text("send-balance")).toContain("USDC");
+        expect(boot.text("confirm-amount")).toContain("USDC");
+    });
+});
+
+describe("with Sepolia active, the bundled list does not name the token", () => {
+    test("on the token screen", async () => {
+        const boot = await bootOnToken("sepolia");
+        expect(boot.visibleViews()).toEqual(["address-token"]);
+        expect(boot.text("address-token-title")).not.toContain("USDC");
+        const info = boot.node("address-token-contract-info").innerHTML;
+        expect(info).not.toContain("Decimals:");
+    });
+
+    test("on the Send screen and the confirmation screen", async () => {
+        const boot = await bootOnToken("sepolia");
+        await reviewSend(boot);
+        expect(boot.text("send-balance")).not.toContain("USDC");
+        expect(boot.text("confirm-amount")).not.toContain("USDC");
+    });
+});

tests/fabricatedDecimals.test.js

@@ -111,13 +111,15 @@ function respondWith(items) {
 }
 
 // Fetch and place the result exactly where refreshBalances() places it, so the
-// approval screens read what a real refresh would have left on state.
+// approval screens read what a real refresh on Ethereum Mainnet would have
+// left on state.
 async function fetchOnto(items, trackedTokens = []) {
     respondWith(items);
     const balances = await fetchTokenBalances(
         HOLDER,
         BLOCKSCOUT,
         trackedTokens,
+        "0x1",
     );
     state.trackedTokens = trackedTokens;
     state.wallets = [

tests/holders.test.js

@@ -192,7 +192,13 @@ describe("the balance-list spam gate", () => {
                 },
             }),
         ]);
-        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+        // On Ethereum Mainnet, the only network the known-token list covers.
+        const balances = await fetchTokenBalances(
+            HOLDER,
+            BLOCKSCOUT,
+            [],
+            "0x1",
+        );
         expect(balances).toHaveLength(1);
         expect(balances[0].holders).toBeNull();
     });

tests/popupFollowsNetworkSwitch.test.js

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

tests/refreshDuringRefresh.test.js

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

tests/resolveTokenSymbol.test.js

@@ -67,13 +67,15 @@ beforeEach(() => {
 });
 
 describe("resolveTokenSymbol", () => {
+    // The bundled list is read only for a token on Ethereum Mainnet.
     test("reads the bundled list", () => {
-        expect(resolveTokenSymbol(USDC, state)).toBe("USDC");
+        expect(resolveTokenSymbol(USDC, { chainId: "0x1" })).toBe("USDC");
     });
 
     test("prefers the bundled list over a tracked entry", () => {
         state.trackedTokens = [{ address: USDC, symbol: "NOTUSDC" }];
-        expect(resolveTokenSymbol(USDC, state)).toBe("USDC");
+        const sources = { chainId: "0x1", trackedTokens: state.trackedTokens };
+        expect(resolveTokenSymbol(USDC, sources)).toBe("USDC");
     });
 
     test("reads a token the user tracks", () => {
@@ -104,7 +106,19 @@ describe("resolveTokenSymbol", () => {
     test("rejects a tracked entry claiming a bundled ticker it is not", () => {
         // NOVEL_TOKEN is not the real USDC contract, so it may not wear USDC.
         state.trackedTokens = [{ address: NOVEL_TOKEN, symbol: "USDC" }];
-        expect(resolveTokenSymbol(NOVEL_TOKEN, state)).toBeNull();
+        const sources = { chainId: "0x1", trackedTokens: state.trackedTokens };
+        expect(resolveTokenSymbol(NOVEL_TOKEN, sources)).toBeNull();
+    });
+
+    // The bundled list holds mainnet contracts, so on Sepolia any contract may
+    // carry one of its symbols.
+    test("on Sepolia, reads a tracked entry carrying a bundled ticker", () => {
+        state.trackedTokens = [{ address: NOVEL_TOKEN, symbol: "USDC" }];
+        const sources = {
+            chainId: "0xaa36a7",
+            trackedTokens: state.trackedTokens,
+        };
+        expect(resolveTokenSymbol(NOVEL_TOKEN, sources)).toBe("USDC");
     });
 
     test("rejects an explorer entry claiming the native ETH ticker", () => {

tests/settingsEndpointSave.test.js

@@ -0,0 +1,169 @@
+// Another page stores a different RPC or Blockscout URL for the same network.
+// Then the user taps "Save" in Settings on this page, on the URL that this page
+// loaded. The URL on screen is stored, and the flash message reads "Saved."
+// (https://git.eeqj.de/sneak/AutistMask/issues/688). Driven through the real
+// popup over a stored profile on Ethereum Mainnet.
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+} = require("./support/popupBoot");
+const { NETWORKS } = require("../src/shared/networks");
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+test.each([
+    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+    },
+])(
+    "$button stores the URL on screen after another page stored a different one",
+    async ({ button, input, field }) => {
+        const page = await bootPopup(unversionedValidProfile());
+        await page.click("btn-settings");
+        const url = page.value(input);
+        // This write sends this page no storage change event.
+        page.storage.write("autistmask", {
+            ...page.storage.read("autistmask"),
+            [field]: "https://other-page.example.invalid",
+        });
+        // This answer passes both endpoint checks on Ethereum Mainnet. The RPC
+        // check reads Ethereum Mainnet's chain id from it. The Blockscout check
+        // reads `ok`.
+        globalThis.fetch.mockResolvedValue({
+            ok: true,
+            json: async () => ({ result: NETWORKS.mainnet.chainId }),
+        });
+
+        await page.click(button);
+
+        expect(page.storage.read("autistmask")[field]).toBe(url);
+        expect(page.text("flash-msg")).toBe("Saved.");
+    },
+);
+
+// The user types a URL in Settings and taps "Save". While the check waits for
+// the endpoint's answer, another page turns "Use Blockscout" on. This page
+// follows that change and draws Settings again, with the stored URL in the
+// input. The check then passes. The typed URL is not stored. The flash message
+// says that the URL was changed during the check
+// (https://git.eeqj.de/sneak/AutistMask/issues/695).
+test.each([
+    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+    },
+])(
+    "$button stores nothing when Settings is drawn again during the check",
+    async ({ button, input, field }) => {
+        const page = await bootPopup(unversionedValidProfile());
+        await page.click("btn-settings");
+        const storedUrl = page.value(input);
+        let answer;
+        globalThis.fetch.mockReturnValue(
+            new Promise((resolve) => {
+                answer = resolve;
+            }),
+        );
+
+        page.node(input).value = "https://typed.example.invalid";
+        const saving = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        // The browser announces this write to this page.
+        await page.storage.local.set({
+            autistmask: {
+                ...page.storage.read("autistmask"),
+                useBlockscout: true,
+            },
+        });
+        await page.settle();
+        expect(page.node("settings-use-blockscout").checked).toBe(true);
+        // This answer passes both endpoint checks on Ethereum Mainnet.
+        answer({
+            ok: true,
+            json: async () => ({ result: NETWORKS.mainnet.chainId }),
+        });
+        await Promise.all(saving);
+        await page.settle();
+
+        expect(page.storage.read("autistmask")[field]).toBe(storedUrl);
+        expect(page.value(input)).toBe(storedUrl);
+        expect(page.text("flash-msg")).toBe(
+            "The URL was not saved because it was changed during the check.",
+        );
+    },
+);
+
+// As above, but another write holds the lock. So this page's follow of the
+// change to "Use Blockscout" waits for the lock. The endpoint answers while the
+// input still shows the typed URL. The save then asks for the lock, after the
+// follow did. So the follow draws Settings again before the save compares the
+// input.
+test.each([
+    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
+    {
+        button: "btn-save-blockscout",
+        input: "settings-blockscout",
+        field: "blockscoutUrl",
+    },
+])(
+    "$button stores nothing when Settings is drawn again while the save waits for the lock",
+    async ({ button, input, field }) => {
+        const page = await bootPopup(unversionedValidProfile());
+        await page.click("btn-settings");
+        const storedUrl = page.value(input);
+        let answer;
+        globalThis.fetch.mockReturnValue(
+            new Promise((resolve) => {
+                answer = resolve;
+            }),
+        );
+        const typedUrl = "https://typed.example.invalid";
+
+        page.node(input).value = typedUrl;
+        const saving = page.node(button).listeners.click.map((fn) => fn());
+        await page.settle();
+        let releaseLock;
+        const lockHeld = navigator.locks.request(
+            "autistmask",
+            () =>
+                new Promise((resolve) => {
+                    releaseLock = resolve;
+                }),
+        );
+        // The browser announces this write to this page.
+        await page.storage.local.set({
+            autistmask: {
+                ...page.storage.read("autistmask"),
+                useBlockscout: true,
+            },
+        });
+        await page.settle();
+        // This answer passes both endpoint checks on Ethereum Mainnet.
+        answer({
+            ok: true,
+            json: async () => ({ result: NETWORKS.mainnet.chainId }),
+        });
+        await page.settle();
+        expect(page.value(input)).toBe(typedUrl);
+        releaseLock();
+        await lockHeld;
+        await Promise.all(saving);
+        await page.settle();
+
+        expect(page.node("settings-use-blockscout").checked).toBe(true);
+        expect(page.storage.read("autistmask")[field]).toBe(storedUrl);
+        expect(page.value(input)).toBe(storedUrl);
+        expect(page.text("flash-msg")).toBe(
+            "The URL was not saved because it was changed during the check.",
+        );
+    },
+);

tests/symbolSpoof.test.js

@@ -72,6 +72,11 @@ const {
 const { renderSendTokenSelect } = require("../src/popup/views/send");
 const { state } = require("../src/shared/state");
 const { debugFetch } = require("../src/shared/log");
+const { NETWORKS } = require("../src/shared/networks");
+
+// The bundled list's symbols are known symbols only on Ethereum Mainnet.
+const MAINNET = NETWORKS.mainnet.chainId;
+const SEPOLIA = NETWORKS.sepolia.chainId;
 
 // The fake "Ethereum" token with symbol "ETH" from the attack documented in
 // README.md, given a holder count high enough to clear every other filter so
@@ -116,14 +121,29 @@ describe("the shared rule", () => {
     });
 
     test("a known symbol from its own contract is not a spoof", () => {
-        expect(isSpoofedSymbol("USDC", USDC_CONTRACT)).toBe(false);
-        expect(isSpoofedSymbol("usdc", USDC_CONTRACT.toUpperCase())).toBe(
-            false,
-        );
+        expect(isSpoofedSymbol("USDC", USDC_CONTRACT, MAINNET)).toBe(false);
+        expect(
+            isSpoofedSymbol("usdc", USDC_CONTRACT.toUpperCase(), MAINNET),
+        ).toBe(false);
     });
 
     test("a known symbol from another contract is a spoof", () => {
-        expect(isSpoofedSymbol("USDC", FAKE_ETH_CONTRACT)).toBe(true);
+        expect(isSpoofedSymbol("USDC", FAKE_ETH_CONTRACT, MAINNET)).toBe(true);
+    });
+
+    // https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled list holds
+    // mainnet contracts, so on Sepolia any contract may carry one of its
+    // symbols.
+    test("on Sepolia, a bundled symbol from any contract is not a spoof", () => {
+        expect(isSpoofedSymbol("USDC", FAKE_ETH_CONTRACT, SEPOLIA)).toBe(false);
+        expect(isSpoofedSymbol("USDC", USDC_CONTRACT, SEPOLIA)).toBe(false);
+    });
+
+    test("on Sepolia, the native asset's labels are still reserved", () => {
+        expect(isSpoofedSymbol("ETH", FAKE_ETH_CONTRACT, SEPOLIA)).toBe(true);
+        expect(isSpoofedSymbol("SepoliaETH", FAKE_ETH_CONTRACT, SEPOLIA)).toBe(
+            true,
+        );
     });
 
     test("a symbol that is not in the table is not judged here", () => {
@@ -164,7 +184,9 @@ describe("the shared rule: symbols that render as a known symbol", () => {
     test("ASCII padding does not buy a pass", () => {
         expect(isSpoofedSymbol(" ETH ", FAKE_ETH_CONTRACT)).toBe(true);
         expect(isSpoofedSymbol("\tETH\n", FAKE_ETH_CONTRACT)).toBe(true);
-        expect(isSpoofedSymbol("  usdc  ", FAKE_ETH_CONTRACT)).toBe(true);
+        expect(isSpoofedSymbol("  usdc  ", FAKE_ETH_CONTRACT, MAINNET)).toBe(
+            true,
+        );
     });
 
     test("non-breaking and other Unicode spaces do not either", () => {
@@ -243,7 +265,9 @@ describe("the shared rule: symbols that render as a known symbol", () => {
 
     test("compatibility forms fold onto the symbol they imitate", () => {
         expect(isSpoofedSymbol(FULLWIDTH_ETH, FAKE_ETH_CONTRACT)).toBe(true);
-        expect(isSpoofedSymbol(FULLWIDTH_USDC, FAKE_ETH_CONTRACT)).toBe(true);
+        expect(
+            isSpoofedSymbol(FULLWIDTH_USDC, FAKE_ETH_CONTRACT, MAINNET),
+        ).toBe(true);
     });
 
     // The two knowingly open classes, asserted here so that the boundary is
@@ -271,8 +295,10 @@ describe("the shared rule: symbols that render as a known symbol", () => {
     });
 
     test("a genuine contract still bears its own padded symbol", () => {
-        expect(isSpoofedSymbol(" USDC ", USDC_CONTRACT)).toBe(false);
-        expect(isSpoofedSymbol(ZWSP + "WETH", WETH_CONTRACT)).toBe(false);
+        expect(isSpoofedSymbol(" USDC ", USDC_CONTRACT, MAINNET)).toBe(false);
+        expect(isSpoofedSymbol(ZWSP + "WETH", WETH_CONTRACT, MAINNET)).toBe(
+            false,
+        );
     });
 
     // Normalization must not invent a match.  Interior ASCII whitespace is
@@ -296,7 +322,7 @@ describe("the shared rule: symbols that render as a known symbol", () => {
             expect(symbol).toMatch(/^[!-~]+$/);
             if (addresses === null) continue;
             for (const address of addresses) {
-                expect(isSpoofedSymbol(symbol, address)).toBe(false);
+                expect(isSpoofedSymbol(symbol, address, MAINNET)).toBe(false);
             }
         }
     });
@@ -317,7 +343,7 @@ describe("the shared rule: symbols that render as a known symbol", () => {
 describe("the shipped token list", () => {
     test("no bundled token is filtered at its own address", () => {
         const filtered = TOKENS.filter((t) =>
-            isSpoofedSymbol(t.symbol, t.address),
+            isSpoofedSymbol(t.symbol, t.address, MAINNET),
         ).map((t) => t.symbol + " @ " + t.address);
         expect(filtered).toEqual([]);
     });
@@ -360,7 +386,9 @@ describe("the shipped token list", () => {
         expect(shared.length).toBeGreaterThan(0);
         for (const [, list] of shared) {
             for (const t of list) {
-                expect(isSpoofedSymbol(t.symbol, t.address)).toBe(false);
+                expect(isSpoofedSymbol(t.symbol, t.address, MAINNET)).toBe(
+                    false,
+                );
             }
         }
     });
@@ -404,7 +432,7 @@ describe("the shipped token list", () => {
                 [...addresses].sort(),
             );
             for (const address of addresses) {
-                expect(isSpoofedSymbol(symbol, address)).toBe(false);
+                expect(isSpoofedSymbol(symbol, address, MAINNET)).toBe(false);
             }
         }
     });
@@ -421,7 +449,9 @@ describe("the shipped token list", () => {
         }
         for (const [symbol, list] of bySymbol) {
             if (list.length < 2) continue;
-            expect(isSpoofedSymbol(symbol, FAKE_ETH_CONTRACT)).toBe(true);
+            expect(isSpoofedSymbol(symbol, FAKE_ETH_CONTRACT, MAINNET)).toBe(
+                true,
+            );
         }
     });
 });
@@ -506,10 +536,40 @@ describe("surface 2: the Send token selector", () => {
     }
 
     beforeEach(() => {
+        state.networkId = "mainnet";
         state.fraudContracts = [];
         state.hideLowHolderTokens = true;
     });
 
+    afterAll(() => {
+        state.networkId = "mainnet";
+    });
+
+    // A token reporting USDC's symbol from another contract.
+    function otherUsdc() {
+        return {
+            address: FAKE_ETH_CONTRACT,
+            symbol: "USDC",
+            decimals: 6,
+            balance: "12.5",
+            holders: 900000,
+        };
+    }
+
+    test("a bundled symbol from another contract is not selectable", () => {
+        render([otherUsdc()]);
+        expect(select.children).toEqual([]);
+    });
+
+    // https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled list holds
+    // mainnet contracts, so on Sepolia any contract may carry its symbols.
+    test("with Sepolia active, a bundled symbol from another contract is selectable", () => {
+        state.networkId = "sepolia";
+        render([otherUsdc()]);
+        expect(select.children).toHaveLength(1);
+        expect(select.children[0].value).toBe(FAKE_ETH_CONTRACT);
+    });
+
     test("a fake ETH token is not selectable", () => {
         render([
             {
@@ -627,7 +687,12 @@ describe("surface 3: the balance list", () => {
                 decimals: "6",
             }),
         ]);
-        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+        const balances = await fetchTokenBalances(
+            HOLDER,
+            BLOCKSCOUT,
+            [],
+            MAINNET,
+        );
         expect(balances).toHaveLength(1);
         expect(balances[0].symbol).toBe(" USDC ");
     });
@@ -641,11 +706,40 @@ describe("surface 3: the balance list", () => {
                 decimals: "6",
             }),
         ]);
-        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+        const balances = await fetchTokenBalances(
+            HOLDER,
+            BLOCKSCOUT,
+            [],
+            MAINNET,
+        );
         expect(balances).toHaveLength(1);
         expect(balances[0].symbol).toBe("USDC");
     });
 
+    // https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled list holds
+    // mainnet contracts, so on Sepolia any contract may carry its symbols.
+    test("a bundled symbol from another contract is listed on Sepolia only", async () => {
+        respondWith([fakeEthItem({ symbol: "USDC", decimals: "6" })]);
+        expect(
+            await fetchTokenBalances(HOLDER, BLOCKSCOUT, [], MAINNET),
+        ).toEqual([]);
+        const sepolia = await fetchTokenBalances(
+            HOLDER,
+            BLOCKSCOUT,
+            [],
+            SEPOLIA,
+        );
+        expect(sepolia).toHaveLength(1);
+        expect(sepolia[0].symbol).toBe("USDC");
+    });
+
+    test("a fake ETH token is filtered on Sepolia too", async () => {
+        respondWith([fakeEthItem()]);
+        expect(
+            await fetchTokenBalances(HOLDER, BLOCKSCOUT, [], SEPOLIA),
+        ).toEqual([]);
+    });
+
     // The trap in this change: the user's real ETH balance is not an ERC-20
     // and is fetched over RPC in refreshBalances, so it never passes through
     // this loop at all.  An explorer row that is not an ERC-20 is dropped

tests/trackedTokenBalances.test.js

@@ -133,13 +133,13 @@ function trackedRow(balance, decimals = null, holders = null) {
     };
 }
 
-async function refresh(addresses, trackedTokens) {
+async function refresh(addresses, trackedTokens, networkId = "mainnet") {
     await refreshBalances(
         [{ addresses }],
         RPC_URL,
         EXPLORER_URL,
         trackedTokens,
-        "mainnet",
+        networkId,
         new AbortController().signal,
     );
     return addresses;
@@ -307,3 +307,76 @@ test("a tracked token wearing a known symbol from another contract is not listed
     );
     expect(first.tokenBalances).toEqual([]);
 });
+
+// https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled list holds
+// Ethereum Mainnet contracts. A token outside the tracked tokens with an
+// unknown holder count is listed only when the bundled list names it.
+test("an untracked bundled token with an unknown holder count is listed on Ethereum Mainnet only", async () => {
+    explorerRows = [explorerRow(USDC, "USDC", 5000000, null)];
+    const [mainnet] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        [],
+    );
+    expect(mainnet.tokenBalances).toEqual([
+        {
+            address: USDC,
+            name: "USDC",
+            symbol: "USDC",
+            decimals: 6,
+            balance: "5.0",
+            holders: null,
+        },
+    ]);
+    const [sepolia] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        [],
+        "sepolia",
+    );
+    expect(sepolia.tokenBalances).toEqual([]);
+});
+
+test("a tracked token at a bundled token's address takes the bundled scale on Ethereum Mainnet only", async () => {
+    holdings[USDC] = { [FIRST]: 5000000n };
+    // The tracked entry records no decimals, and Blockscout fails.
+    const tracked = [
+        { address: USDC, symbol: "USDC", name: "USD Coin", decimals: null },
+    ];
+    const row = (balance) => ({
+        address: USDC,
+        name: "USD Coin",
+        symbol: "USDC",
+        decimals: null,
+        balance: balance,
+        holders: null,
+    });
+    const [mainnet] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        tracked,
+    );
+    expect(mainnet.tokenBalances).toEqual([row("5.0")]);
+    const [sepolia] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        tracked,
+        "sepolia",
+    );
+    expect(sepolia.tokenBalances).toEqual([row(null)]);
+});
+
+test("with Sepolia active, a tracked token wearing a bundled symbol from another contract is listed", async () => {
+    holdings[OTHER] = { [FIRST]: 5000000n };
+    const [first] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        [{ address: OTHER, symbol: "USDC", name: "Other", decimals: 6 }],
+        "sepolia",
+    );
+    expect(first.tokenBalances).toEqual([
+        {
+            address: OTHER,
+            name: "Other",
+            symbol: "USDC",
+            decimals: null,
+            balance: "5.0",
+            holders: null,
+        },
+    ]);
+});

tests/trackedTokensPerNetwork.test.js

@@ -5,6 +5,9 @@
 // a contract lookup that answers after one. Driven through the real popup over
 // a stored profile; the same switch made by the background is in
 // tests/coldWorkerChainSwitch.test.js.
+//
+// The tests of what another page stored before a switch in Settings cover a
+// fraud contract too (https://git.eeqj.de/sneak/AutistMask/issues/692).
 
 const {
     bootPopup,
@@ -177,6 +180,164 @@ test("a token added by contract address on Sepolia is tracked on Sepolia only",
     expect(onSepolia).not.toContain("DAI");
 });
 
+// Another popup page tracks DAI on Ethereum Mainnet after this page's last
+// save. The switch to Sepolia puts DAI away under Ethereum Mainnet.
+test("a token another page tracked before a switch in Settings stays tracked on Ethereum Mainnet", async () => {
+    const boot = await bootPopup(unversionedValidProfile());
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        trackedTokens: [MAINNET_TOKEN],
+    });
+
+    await boot.click("btn-settings");
+    await chooseNetwork(boot, "sepolia");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([MAINNET_TOKEN]);
+});
+
+// Another popup page stops tracking DAI on Ethereum Mainnet after this page's
+// last save. This page still holds DAI. The switch to Sepolia does not store
+// DAI under Ethereum Mainnet again.
+test("a token another page removed before a switch in Settings stays removed", async () => {
+    const boot = await bootPopup(
+        unversionedValidProfile({ trackedTokens: [MAINNET_TOKEN] }),
+    );
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        trackedTokens: [],
+    });
+
+    await boot.click("btn-settings");
+    await chooseNetwork(boot, "sepolia");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([]);
+});
+
+// Another popup page removes DAI after this page's last save. That page then
+// adds DAI again, typing the contract address in lower case. The two pages'
+// entries for DAI match, because contract addresses are compared ignoring
+// letter case. The switch to Sepolia keeps this page's entry under Ethereum
+// Mainnet.
+test("a token another page added again with a lower-case address keeps this page's entry", async () => {
+    const boot = await bootPopup(
+        unversionedValidProfile({ trackedTokens: [MAINNET_TOKEN] }),
+    );
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        trackedTokens: [
+            { ...MAINNET_TOKEN, address: MAINNET_TOKEN.address.toLowerCase() },
+        ],
+    });
+
+    await boot.click("btn-settings");
+    await chooseNetwork(boot, "sepolia");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.networkTrackedTokens.mainnet).toEqual([MAINNET_TOKEN]);
+});
+
+// Another popup page saves a switch to Sepolia after this page's last save.
+// TST is tracked on Sepolia. This page has not taken that switch yet. A switch
+// to Sepolia in this page's Settings keeps TST off Ethereum Mainnet's list.
+test("a token tracked on Sepolia when another page switched there is not tracked on Ethereum Mainnet", async () => {
+    const boot = await bootPopup(unversionedValidProfile());
+    expect(boot.pageErrors).toEqual([]);
+    await boot.click("btn-settings");
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        networkId: "sepolia",
+        trackedTokens: [SEPOLIA_TOKEN],
+    });
+
+    await chooseNetwork(boot, "sepolia");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([SEPOLIA_TOKEN]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([]);
+});
+
+// Another popup page records a fraud contract on Ethereum Mainnet after this
+// page's last save. The switch to Sepolia drops that fraud contract, as the
+// switch drops this page's own.
+test("a fraud contract another page recorded before a switch in Settings is not kept on Sepolia", async () => {
+    const boot = await bootPopup(unversionedValidProfile());
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        fraudContracts: [NEW_TOKEN_ADDRESS],
+    });
+
+    await boot.click("btn-settings");
+    await chooseNetwork(boot, "sepolia");
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.fraudContracts).toEqual([]);
+});
+
+// The contract lookup on SettingsAddToken answers on Ethereum Mainnet while the
+// switch to Sepolia waits for the lock. The page adds the token to Ethereum
+// Mainnet's list. The switch then keeps that list for Ethereum Mainnet.
+test("a token added while a switch in Settings waits for the lock stays tracked on Ethereum Mainnet", async () => {
+    const boot = await bootOnAddToken("mainnet");
+    expect(boot.pageErrors).toEqual([]);
+    const { lookupTokenInfo } = require("../src/shared/balances");
+    let answer;
+    lookupTokenInfo.mockImplementationOnce(
+        () =>
+            new Promise((resolve) => {
+                answer = resolve;
+            }),
+    );
+    boot.node("settings-addtoken-address").value = NEW_TOKEN_ADDRESS;
+    const adding = boot.click("btn-settings-addtoken-manual");
+    await boot.click("btn-settings");
+
+    // Another write holds the lock, so the switch's save waits for it.
+    let releaseLock;
+    const lockHeld = navigator.locks.request(
+        "autistmask",
+        () =>
+            new Promise((resolve) => {
+                releaseLock = resolve;
+            }),
+    );
+    const select = boot.node("settings-network");
+    select.value = "sepolia";
+    const switching = Promise.all(select.listeners.change.map((fn) => fn()));
+    await boot.settle();
+
+    answer({ symbol: "NEW", decimals: 18, name: "New Token" });
+    await boot.settle();
+    releaseLock();
+    await lockHeld;
+    await switching;
+    await adding;
+
+    const stored = boot.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.trackedTokens).toEqual([]);
+    expect(stored.networkTrackedTokens.mainnet).toEqual([
+        {
+            address: NEW_TOKEN_ADDRESS,
+            symbol: "NEW",
+            decimals: 18,
+            name: "New Token",
+        },
+    ]);
+});
+
 describe("Back after a switch from the Settings gear", () => {
     test("SettingsAddToken no longer offers the common tokens", async () => {
         const boot = await bootOnAddToken("mainnet");

tests/transactionDetailLateAnswer.test.js

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

tests/transactions.test.js

@@ -144,6 +144,7 @@ function tokenTx(overrides = {}) {
         isError: false,
         contractAddress: USDC_CONTRACT,
         holders: 3500000,
+        chainId: "0x1",
         ...overrides,
     };
 }
@@ -259,6 +260,32 @@ describe("known-symbol spoof verification", () => {
         expect(result.newFraudContracts).toEqual([NOVEL_SPAM_CONTRACT]);
     });
 
+    // https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled list holds
+    // mainnet contracts, so its symbols are not known symbols on Sepolia.
+    test("on Sepolia, a bundled symbol from another contract is kept", () => {
+        const sepoliaToken = tokenTx({
+            symbol: "USDC",
+            contractAddress: NOVEL_SPAM_CONTRACT,
+            holders: 5000000,
+            chainId: "0xaa36a7",
+        });
+        const result = filterTransactions([sepoliaToken], filters());
+        expect(result.transactions).toEqual([sepoliaToken]);
+        expect(result.newFraudContracts).toEqual([]);
+    });
+
+    test('on Sepolia, "ETH" as an ERC-20 is still spoofed', () => {
+        const fakeEth = tokenTx({
+            symbol: "ETH",
+            contractAddress: NOVEL_SPAM_CONTRACT,
+            holders: 5000000,
+            chainId: "0xaa36a7",
+        });
+        expect(filterTransactions([fakeEth], filters()).transactions).toEqual(
+            [],
+        );
+    });
+
     test("the genuine contract for that symbol is not spoofed", () => {
         const genuine = tokenTx();
         const result = filterTransactions([genuine], filters());
@@ -1495,6 +1522,41 @@ describe("fetchRecentTransactions merge and dedup", () => {
         expect(mainnet[0].chainId).toBe("0x1");
     });
 
+    // https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled token list
+    // names a contract only on Ethereum Mainnet. On Sepolia, a call to the
+    // contract at USDC's mainnet address is labelled with the network's native
+    // currency. A call to any contract the wallet does not name gets that label.
+    test("a contract call on Sepolia is not named by the bundled list", async () => {
+        respondWith(
+            [
+                {
+                    hash: "0x" + "b".repeat(64),
+                    block_number: 21000095,
+                    timestamp: TS,
+                    from: { hash: VICTIM },
+                    to: { hash: USDC_CONTRACT, is_contract: true },
+                    value: "0",
+                    method: "approve",
+                    status: "ok",
+                },
+            ],
+            [],
+        );
+        const sepolia = await fetchRecentTransactions(
+            VICTIM,
+            BLOCKSCOUT,
+            "0xaa36a7",
+        );
+        expect(sepolia[0].directionLabel).toBe("Approve");
+        expect(sepolia[0].symbol).toBe("SepoliaETH");
+        const mainnet = await fetchRecentTransactions(
+            VICTIM,
+            BLOCKSCOUT,
+            "0x1",
+        );
+        expect(mainnet[0].symbol).toBe("USDC");
+    });
+
     test("the fake token transfer survives fetching and is then filtered", async () => {
         respondWith(
             [],

tests/uniswap.test.js

@@ -3440,6 +3440,82 @@ describe("uniswap decoder", () => {
             });
         });
 
+        // https://git.eeqj.de/sneak/AutistMask/issues/685 — Permit2 moves no
+        // ETH, so a PERMIT2_TRANSFER_FROM of the zero address reads as a move
+        // of a token nothing knows. On next at ec6b6b5 its lines read ETH,
+        // with an ETH figure.
+        describe("a PERMIT2_TRANSFER_FROM of the zero address", () => {
+            const MOVED_AMOUNT =
+                "1000000000000000000 base units (decimals unknown)";
+
+            test("to another address names the address", () => {
+                const result = decodeSteps(
+                    [0x00, 0x02],
+                    [V3_600, transfer(ZERO_ADDR, OTHER_ADDR, ONE_WETH)],
+                );
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "600.0000 USDT"],
+                    ["Moved from the sender", MOVED_AMOUNT],
+                    ["Token moved", ZERO_ADDR],
+                    ["Moved to", OTHER_ADDR],
+                ]);
+                expect(detail(result, "Token moved").address).toBe(ZERO_ADDR);
+            });
+
+            test("into the router names the address", () => {
+                const result = decodeSteps(
+                    [0x02, 0x00],
+                    [transfer(ZERO_ADDR, ROUTER_ADDR, ONE_WETH), V3_600],
+                );
+                expect(detail(result, "Paid to").value).toBe(
+                    "The router, " +
+                        MOVED_AMOUNT +
+                        " from the sender (later steps may not spend all of it)",
+                );
+                expect(detail(result, "Token moved into the router")).toEqual({
+                    label: "Token moved into the router",
+                    value: ZERO_ADDR,
+                    address: ZERO_ADDR,
+                    isToken: true,
+                });
+            });
+
+            // The V4 step's SETTLE names the user as payer and states no
+            // amount. The step's lines say that the ETH amount is not known.
+            test("after a V4 exact-out step of ETH, also shows that the ETH amount is not known", () => {
+                const v4EthExactOut = encodeV4Swap(
+                    new Uint8Array([
+                        V4_SWAP_EXACT_OUT_SINGLE_ID,
+                        V4_SETTLE_ID,
+                        V4_TAKE_ALL_ID,
+                    ]),
+                    [
+                        encodeV4ExactOutSingle(
+                            ZERO_ADDR,
+                            USDC_ADDR,
+                            590000000n,
+                            ONE_WETH,
+                        ),
+                        encodeV4Settle(ZERO_ADDR),
+                        encodeV4TakeAll(USDC_ADDR, 0n),
+                    ],
+                );
+                const result = decodeSteps(
+                    [0x10, 0x02],
+                    [v4EthExactOut, transfer(ZERO_ADDR, OTHER_ADDR, ONE_WETH)],
+                );
+                expect(detail(result, "Token In").value).toBe("ETH (native)");
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Moved from the sender", UNDECODED],
+                    ["Token moved", "ETH"],
+                    ["Moved to", "The swap step that spends it"],
+                    ["Moved from the sender", MOVED_AMOUNT],
+                    ["Token moved", ZERO_ADDR],
+                    ["Moved to", OTHER_ADDR],
+                ]);
+            });
+        });
+
         // https://git.eeqj.de/sneak/AutistMask/issues/682 — V4 pays a SETTLE
         // of ETH from the router's own ETH, whichever payer the SETTLE names,
         // and the router holds the transaction's value. On next at 36b2002 a
@@ -4304,10 +4380,9 @@ describe("uniswap decoder", () => {
         expect(detail(result, "Min. received").value).toBe("2.0000 USDC");
     });
 
-    // With no minimum stated before it, a zero balance check is what sets the
-    // output side, and it guarantees nothing. No step pays anyone, so the
-    // minimum is not said to be received.
-    test("a zero balance check with no earlier minimum states no minimum", () => {
+    // A zero balance check sets neither Token Out nor the minimum. The route
+    // pays only the WRAP_ETH's WETH, to the router, where it stays.
+    test("a zero balance check after a WRAP_ETH into the router names no output token and no minimum", () => {
         const data = buildExecute(
             solidityPacked(["uint8", "uint8"], [0x0b, 0x0e]),
             [
@@ -4320,9 +4395,16 @@ describe("uniswap decoder", () => {
         const result = uniswap.decode(data, ROUTER_ADDR, "0x1", {}, USER_ADDR);
         expect(result).not.toBeNull();
 
-        expect(detail(result, "Token Out").value).toContain("USDT");
-        expect(detail(result, "Min. paid out").value).toBe(
-            "None (no minimum guaranteed)",
+        expect(detail(result, "Token Out").value).toBe(
+            "Unknown (not named in the calldata)",
+        );
+        expect(detail(result, "Min. paid out")).toBeUndefined();
+        expect(detail(result, "Min. received")).toBeUndefined();
+        expect(detail(result, "Paid to").value).toBe(
+            "The router, where it stays (no later step pays it out)",
+        );
+        expect(detail(result, "Token moved into the router").address).toBe(
+            WETH_ADDR,
         );
     });
 

tests/uniswapRecipient.test.js

@@ -688,6 +688,62 @@ describe("an UNWRAP_WETH makes the output ETH only when the router holds it", ()
         ]);
     });
 
+    // The same route, then a balance check of the sender's USDC with a zero
+    // minimum. The check guarantees nothing, so Token Out stays ETH
+    // (https://git.eeqj.de/sneak/AutistMask/issues/649).
+    test("the same route, then a zero balance check of USDC, still reads as ETH with no minimum", () => {
+        const result = decode(
+            execute(
+                v4Swap(
+                    SWAP_USDT_FOR_WETH,
+                    SETTLE_USDT,
+                    take(WETH, MSG_SENDER, (ONE_WETH * 6n) / 10n),
+                    take(WETH, ADDRESS_THIS),
+                ),
+                unwrapWeth(MSG_SENDER),
+                balanceCheck(USDC, 0n),
+            ),
+        );
+        expect(result.name).toBe("Swap USDT → ETH");
+        expect(detail(result, "Token Out").value).toBe("ETH");
+        expect(labels(result)).toEqual([
+            "Protocol",
+            "Token In",
+            "Amount",
+            "Token Out",
+            "Steps",
+            "Deadline",
+        ]);
+    });
+
+    // A PERMIT2_TRANSFER_FROM moves the sender's WETH into the router. An
+    // UNWRAP_WETH pays that WETH to the user as ETH. A zero balance check of
+    // USDC sets neither Token Out nor the minimum, before the UNWRAP_WETH or
+    // after it (https://git.eeqj.de/sneak/AutistMask/issues/649).
+    test.each([
+        {
+            kind: "before the UNWRAP_WETH",
+            steps: [balanceCheck(USDC, 0n), unwrapWeth(MSG_SENDER)],
+        },
+        {
+            kind: "after the UNWRAP_WETH",
+            steps: [unwrapWeth(MSG_SENDER), balanceCheck(USDC, 0n)],
+        },
+    ])(
+        "WETH moved into the router and unwrapped, with a zero balance check of USDC $kind, reads as ETH with no minimum",
+        ({ steps }) => {
+            const result = decode(
+                execute(
+                    permit2TransferFrom(WETH, ADDRESS_THIS, ONE_WETH),
+                    ...steps,
+                ),
+            );
+            expect(detail(result, "Token Out").value).toBe("ETH");
+            expect(detail(result, "Min. received")).toBeUndefined();
+            expect(detail(result, "Min. paid out")).toBeUndefined();
+        },
+    );
+
     // A TAKE the decoder cannot read may pay part of the WETH to the user.
     test("one V4 step paying WETH to the router beside a TAKE that cannot be read, then an UNWRAP_WETH, reads as ETH with no minimum", () => {
         const result = decode(
@@ -2820,17 +2876,16 @@ describe("the allow-revert flag", () => {
         },
     );
 
-    test("a BALANCE_CHECK_ERC20 with the flag, and no minimum before it, states none", () => {
+    test("a BALANCE_CHECK_ERC20 with the flag, and no minimum before it, names no output token and no minimum", () => {
         const check = balanceCheck(WETH, ONE_WETH);
         expect(detail(decode(execute(check)), "Min. paid out").value).toBe(
             "1.0000 WETH",
         );
 
         const withFlag = decode(execute(flagged(check)));
-        expect(detail(withFlag, "Token Out").address).toBe(WETH);
-        expect(detail(withFlag, "Min. paid out").value).toBe(
-            "None (no minimum guaranteed)",
-        );
+        expect(detail(withFlag, "Token Out").value).toBe(UNNAMED);
+        expect(detail(withFlag, "Min. paid out")).toBeUndefined();
+        expect(detail(withFlag, "Min. received")).toBeUndefined();
     });
 
     // Only the routers from UniversalRouterV2 on let a PERMIT2_PERMIT fail.

tests/unknownScaleSend.test.js

@@ -167,7 +167,8 @@ function row(token = {}, value = FIVE_WETH) {
 }
 
 // Fetch the explorer's rows through the real fetcher and put them exactly where
-// refreshBalances() puts them. The node reports the holding the explorer does.
+// refreshBalances() puts them on Ethereum Mainnet. The node reports the holding
+// the explorer does.
 async function fetchOnto(items) {
     mockProvider.tokenUnits = BigInt(items[0].value);
     debugFetch.mockImplementation(async () => ({
@@ -176,7 +177,7 @@ async function fetchOnto(items) {
         statusText: "OK",
         json: async () => items,
     }));
-    const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+    const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, [], "0x1");
     state.wallets = [
         {
             name: "Wallet 1",