fix: closing a transaction or signature approval window leaves the request pending (closes #673)

The browser can close the approval window when the user clicks away from it,
for example to copy the password from a password manager. Closing it used to
reject the request with 4001. Now the request stays pending and the site gets
no answer. Until it is answered, the toolbar popup opens the oldest such
approval. The toolbar popup skips an approval while its transaction is being
sent or its signature checked. A worker that starts holds no approvals, so it
points the toolbar popup back at the wallet.

Reject now closes its window only after the background has the rejection. A
rejection the background refuses leaves the window open with the background's
message.

Site-connection and network-switch windows still reject the request when
closed.

Model: opus-5-5

README.md

@@ -12,16 +12,29 @@ intercepts tx status links to their own site instead of going to Etherscan, etc.
 None of the common alternatives work on Firefox.
 
 Hence, a minimally viable ERC20 browser wallet/signer that works cross-platform.
-Everything you need, nothing you don't. We import as few libraries as possible,
-don't implement any crypto, and don't send user-specific data anywhere but a
-(user-configurable) Ethereum RPC endpoint (which defaults to a public node). The
-extension contacts three user-configurable services: the configured RPC node for
-blockchain interactions, a public CoinDesk API (no API key) for realtime price
-information, and a Blockscout block-explorer API for transaction history and
-token balances. It also performs best-effort Etherscan address label lookups
-during transaction confirmation. A community-maintained phishing domain
-blocklist is built into the extension at build time and checked locally; nothing
-is fetched for it at runtime.
+Everything you need, nothing you don't. We import as few libraries as possible
+and don't implement any crypto. By default the wallet sends user-specific data
+only to the Ethereum RPC endpoint. The user can change that endpoint in
+Settings. The endpoint defaults to a public node.
+
+Out of the box the extension contacts two services:
+
+- the configured RPC node, for blockchain interactions
+- a public CoinDesk API (no API key), for realtime prices. The API receives
+  token symbols and nothing else.
+
+Two more services are sent none of the user's data until the user ticks a
+checkbox for each. Welcome and Settings both offer the two checkboxes:
+
+- "Use Blockscout": a Blockscout block-explorer API, used for:
+    - transaction history
+    - the tokens the user has not tracked
+    - transaction details
+- "Check recipients on Etherscan": a best-effort Etherscan label lookup of the
+  recipient during transaction confirmation
+
+A community-maintained phishing domain blocklist is built into the extension at
+build time and checked locally. Nothing is fetched for it at runtime.
 
 In the extension is a hardcoded list of the top ERC20 contract addresses. You
 can add any ERC20 contract by contract address if you wish, but the hardcoded
@@ -422,6 +435,35 @@ It also covers the red banner on the Settings screen: switching the network
 there to Sepolia must put up the `[TESTNET]` banner, and switching back to
 mainnet must take it down, both while Settings is still on screen.
 
+It also covers what a new install sends to Blockscout and Etherscan
+([#668](https://git.eeqj.de/sneak/AutistMask/issues/668)). The harness installs
+a route handler before the first popup page opens. From then on, the handler
+records every request the extension makes, from its pages and from its
+background worker. The background worker starts earlier, but it makes no request
+while it starts up. The tests take these steps in order:
+
+- Welcome must offer "Use Blockscout" and "Check recipients on Etherscan"
+  unticked.
+- With neither ticked, Home, AddressDetail, AddressToken and ConfirmTx must each
+  show the line saying what is off.
+- The popup is then closed until the background has run a balance refresh of its
+  own. No recorded request may have gone to Blockscout or Etherscan.
+- "Use Blockscout" is ticked from AddressDetail's gear. On "Back", AddressDetail
+  must ask Blockscout for its history and no longer say the setting is off.
+  Blockscout must then be asked for the token balances.
+- The stub Blockscout then reports a token the user has not tracked. Home lists
+  it. "Use Blockscout" is unticked from AddressDetail's gear. On "Back", the
+  token must be gone from AddressDetail, from Send's token dropdown and from
+  Home. Those three screens must each show the line saying the setting is off.
+  The setting is then ticked again.
+- "Check recipients on Etherscan" is ticked from ConfirmTx's gear. On "Back",
+  ConfirmTx must ask Etherscan about the recipient and show the label the stub
+  page gives the recipient.
+
+Both settings stay on for the rest of the run. TransactionDetail with "Use
+Blockscout" off is not driven here: while the setting is off, there is no
+history row to open it from. The unit tests cover that case.
+
 It also covers the confirmation screen, for both a native ETH send and an ERC-20
 send: Send disabled while the fee estimate is in flight, enabled once it lands,
 the fee block quoting the expected cost and the reserve separately, the distinct
@@ -461,14 +503,18 @@ address, the transaction assertions run against the raw signed transaction
 captured at `eth_sendRawTransaction` rather than against anything the extension
 reported, rejecting each prompt is required to return a rejection to the page
 rather than hang or resolve, a network switch request is required to leave the
-stored network unchanged and send no `chainChanged` until it is approved, a
-network switch in Settings is required to send the page `chainChanged` with the
-new chain id, a prompt raised while another approval window has focus is
-required to open a window of its own, and the password is required to be absent
-from every message the approval window sends to the background — with the
-message that would carry it required to be present, so that check cannot pass by
-observing nothing. That last one is the standing floor under
-[#157](https://git.eeqj.de/sneak/AutistMask/issues/157).
+stored network unchanged and send no `chainChanged` until it is approved, the
+popup open all along is required to show the `[TESTNET]` banner once a switch to
+Sepolia is approved and to drop it once the switch back is, a network switch in
+Settings is required to send the page `chainChanged` with the new chain id, a
+prompt raised while another approval window has focus is required to open a
+window of its own, and the password is required to be absent from every message
+the approval window sends to the background — with the message that would carry
+it required to be present, so that check cannot pass by observing nothing. That
+last one is the standing floor under
+[#157](https://git.eeqj.de/sneak/AutistMask/issues/157). A transaction or
+signature approval whose window is closed is required to leave the page without
+an answer. The suite then answers it from the page the toolbar button opens.
 
 The limits of that coverage and of the rest of the Chrome suite, none of them
 papered over:
@@ -477,9 +523,9 @@ papered over:
   network with real funds; that remains a human pass before 1.0.0.
 - The site-connection prompt is raised through `chrome.action.openPopup()`, and
   headless Chromium's browser-action popup is not a page Playwright can see or
-  click, so that one prompt is driven at the URL the extension itself puts on
-  the action — the same page and the same approval id, but whether a real
-  toolbar click shows it is not observable here.
+  click. So that prompt, and an approval reopened after its window closed, are
+  opened in a tab at the URL the extension puts on the action. Whether a real
+  toolbar click shows that page is not observable here.
 - Each site-connection request is made 1.5 seconds after the tab it will be
   driven in is opened (`APPROVAL_TAB_SETTLE_MS` in `tests/e2e/run.js`), because
   opening that tab closes the previous prompt's toolbar popup; a request made
@@ -598,14 +644,24 @@ above, it does not fail on page errors.
 
 `make test-e2e-firefox` builds `dist/firefox/` and drives the **real popup in a
 real Firefox**, installed as an unpacked MV2 temporary add-on via geckodriver.
-It covers popup load, the StateRecovery screen (the same cases as the Chrome
-suite), wallet creation through the UI, the Add Token screen, and the dApp round
-trips — `eth_requestAccounts`, `personal_sign`, `wallet_switchEthereumChain`
-rejected and then approved, `eth_sendTransaction`, and a closed approval window
-rejecting with EIP-1193 4001 — driven through the real content script,
-background page and approval windows. The `personal_sign` prompt is also
-required to fit its window without scrolling sideways, with the extension's
-pages at 170% zoom.
+It covers:
+
+- popup load
+- the StateRecovery screen, with the same cases as the Chrome suite
+- wallet creation through the UI
+- the Add Token screen
+- `eth_requestAccounts` from a dApp
+- `personal_sign` from a dApp
+- `wallet_switchEthereumChain` from a dApp, rejected and then approved
+- `eth_sendTransaction` from a dApp
+- an approval window closed without an answer, which leaves its request pending
+  until it is rejected
+
+Each dApp request runs through the real content script and background page, and
+opens a real approval window. The popup open all along is required to show the
+`[TESTNET]` banner once the switch to Sepolia is approved and to drop it once
+the switch back is. The `personal_sign` prompt is also required to fit its
+window without scrolling sideways, with the extension's pages at 170% zoom.
 
 The suite lives in `tests/e2e/firefox/`. Its WebDriver client (`driver.js`) has
 **no npm dependencies at all**: it is built on global `fetch` and
@@ -721,13 +777,11 @@ Three limits are worth knowing, all real differences from the Chrome suite:
   in `tests/e2e/dapp.js`, which serves the dApp page and a JSON-RPC node and
   which the extension's `rpcUrl` is pointed at for the dApp steps; a JSON-RPC
   method that fixture does not model fails the run rather than answering `null`.
-  Everything else, Blockscout and the price feed among it, has no fixture and
-  simply fails, and the extension swallows its own fetch failures, so only the
-  _failure_ branches of that code are ever executed. A `ReferenceError` in the
-  success path of `renderTransactions`, or of price rendering, passes this suite
-  green. The offline run is also weaker than the Chrome suite's interception for
-  those calls: it proves nothing got out, but it cannot report which requests
-  were attempted.
+  The suite leaves "Use Blockscout" off, so Blockscout is not asked. A
+  `ReferenceError` in the success path of `renderTransactions`, or of price
+  rendering, passes this suite green. The offline run is also weaker than the
+  Chrome suite's interception: it proves nothing got out, but it cannot report
+  which requests were attempted.
 - **The site-connection prompt always opens in a window of its own.** The
   profile turns off `extensions.openPopupWithoutUserGesture.enabled`, so
   `src/background/index.js` falls back from the toolbar popup, which WebDriver
@@ -842,13 +896,16 @@ src/
     views/            — one JS module per screen (home, send, approval, etc.)
   shared/             — modules used by both popup and background
     alarms.js         — recurring background jobs (extension alarms API)
-    balances.js       — ETH + ERC-20 balance fetching via RPC + Blockscout
+    balances.js       — ETH and tracked token balances via RPC, others via
+                        Blockscout while "Use Blockscout" is on
     constants.js      — chain IDs, default RPC endpoint, ERC-20 ABI
     ens.js            — ENS forward/reverse resolution (popup only)
     holders.js        — holder-count parsing and the low-holder rule
     prices.js         — ETH/USD and token/USD via CoinDesk API
     scamlist.js       — known fraud contract addresses
     state.js          — persisted state (extension storage)
+    storedSettings.js — "Use Blockscout" and "Check recipients on Etherscan",
+                        read from storage for the requests those settings gate
     symbolSpoof.js    — the known-symbol spoof rule, shared by all surfaces
     tokenList.js      — top ERC-20 tokens by market cap (hardcoded)
     transactions.js   — tx history fetching + anti-poisoning filters
@@ -1119,25 +1176,39 @@ with the same floor (`.5` reads `.5000`).
 
 **Specific Exception — unknown token scale:** Calldata carries base units and no
 scale, so every amount on the dApp approval screen needs the token's `decimals`.
-It is resolved from the bundled token list, then from the tokens the user tracks
-on the network the transaction is for, then, when that is the active network,
-from what the block explorer reported for the contract in the wallet's balances,
-which are the active network's only (`resolveTokenDecimals()` in
-`src/shared/approvalAmount.js`). Where none of them answers, the amount is not
-formatted: the line reads `5000000000 base units (decimals unknown)`. A guessed
-scale is not an approximation but a different number — 1,000 units of a
-6-decimal token formatted at 18 decimals reads `0.000000001` — on the screen
-whose only job is to state what is being authorized. Both amount paths of that
-screen take this rule: the ERC-20 `transfer`/`approve` line
-(`src/popup/views/approval.js`) and the swap's `Amount`, `Min. received`,
-`Moved from the sender` and `Permit2 allowance` lines and the `Paid to` line of
-a move into the router (`src/shared/uniswap.js`). The token permission warning
-on the signature screen takes the same rule for its amounts. An unbounded
-allowance or permit needs no scale to describe and is still shown as
-`Unlimited`. A source's answer counts only if it is a whole number from 0 to 80:
-`decimals()` returns a `uint8`, but `formatUnits()` cannot format more than 80
-decimal places, so a token that reports 81 to 255 is shown as one whose scale
-nothing knows.
+The wallet takes the `decimals` from these sources, in this order
+(`resolveTokenDecimals()` in `src/shared/approvalAmount.js`):
+
+- the bundled token list
+- the tokens the user tracks on the network the transaction is for
+- what the block explorer reported for the contract in the wallet's balances.
+  Those balances cover the active network only. This source is used only while
+  "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:
+
+- TxApproval and SignApproval
+- WaitTx, SuccessTx and ErrorTx, which follow TxApproval
+
+Where none of the sources answers, the amount is not formatted. The amount line
+then reads `5000000000 base units (decimals unknown)`. A guessed scale is not an
+approximation but a different number — 1,000 units of a 6-decimal token
+formatted at 18 decimals reads `0.000000001` — on the screen whose only job is
+to state what is being authorized. Both amount paths of that screen take this
+rule: the ERC-20 `transfer`/`approve` line (`src/popup/views/approval.js`) and
+the swap's `Amount`, `Min. received`, `Moved from the sender` and
+`Permit2 allowance` lines and the `Paid to` line of a move into the router
+(`src/shared/uniswap.js`). The token permission warning on the signature screen
+takes the same rule for its amounts. An unbounded allowance or permit needs no
+scale to describe and is still shown as `Unlimited`. A source's answer counts
+only if it is a whole number from 0 to 80: `decimals()` returns a `uint8`, but
+`formatUnits()` cannot format more than 80 decimal places, so a token that
+reports 81 to 255 is shown as one whose scale nothing knows.
 
 The rule holds only if nothing invents a scale UPSTREAM of it. Those three
 sources are read as authoritative, so a value written into one of them cannot be
@@ -1160,18 +1231,19 @@ and compare against. Reading the stored field directly instead answers `null`
 for a bundled or tracked token the explorer merely omitted, which is not a
 refusal the wallet has any reason to make.
 
-The Send screen also consults every address's explorer reports, so a contract
-two addresses report different `decimals` for has no scale there, and the stored
-balance, formatted at one of those scales, is withdrawn with it. The Send
-screen's `Current balance` and the confirmation screen's balance line then both
-read `unknown (SYMBOL)`. The balance list formats each explorer row as it is
-fetched, without that cross-address check, and shows the row's figure.
+While "Use Blockscout" is on, the Send screen also consults every address's
+explorer reports. The reports for two addresses may give different `decimals`
+for one contract. That token then has no scale on Send. Its stored balance is
+not shown either. The Send screen's `Current balance` and the confirmation
+screen's balance line then both read `unknown (SYMBOL)`. The balance list
+formats each explorer row as it is fetched, without that cross-address check,
+and shows the row's figure.
 
 **Decoded amount lines on the transaction approval screen:** the `Amount` line
 of a decoded ERC-20 call, and the `Amount` and `Min. received` lines of a
 decoded swap (see TxApproval below; `Min. received` reads `Min. paid out` unless
-only the user is paid, see Transaction Decoding), do not always read as a
-number. They can read:
+only the user is paid and no allowance goes to a spender other than the router,
+see Transaction Decoding), do not always read as a number. They can read:
 
 - A formatted quantity, e.g. `17.1900 USDT`, when the token's scale is known:
   truncated to four decimals, with the floor and the zero cases described above.
@@ -1240,7 +1312,11 @@ only when no earlier step set it. It finds each side by three rules:
    is their sum; in any other case the step gives no `Amount`. The decoder reads
    no amount from an exact-out action, and an open delta is not a stated amount.
    Its `Min. received` is found the same way, from the `amountOutMin` of the
-   actions that buy the output currency.
+   actions that buy the output currency, except that the step gives none when a
+   swap action in it also spends the output currency, because the step then does
+   not pay out all that those actions buy. A step that buys at least 0.5 WETH
+   with USDT and swaps 0.3 WETH of it for USDC, with WETH as its output side,
+   gives no `Min. received`.
 3. If any swap action in the step could not be read, only `SETTLE`,
    `SETTLE_ALL`, `TAKE` and `TAKE_ALL` name its sides, and the step gives no
    `Amount` or `Min. received`. A side they did not name is unknown, and the
@@ -1372,25 +1448,48 @@ The core hierarchy is **Wallets → Addresses**:
 - The user can have multiple wallets, each with multiple addresses (HD) or a
   single address (key).
 
-Which tokens an address shows is decided by `fetchTokenBalances()` in
-`src/shared/balances.js`, from the Blockscout `token-balances` response, so
-tokens do appear without the user adding them. An ERC-20 is shown when its
-balance is nonzero and it is in the bundled known-token list, is tracked by the
-user, or has 1,000 or more holders; a token claiming a symbol from the bundled
-list from any other contract address is always dropped, 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
+Which tokens an address shows is decided on every refresh by `refreshBalances()`
+in `src/shared/balances.js`. The balance of each token tracked on the active
+network is read with `balanceOf` through the RPC endpoint, for every address.
+Its holder count and `decimals` are those of Blockscout's entry for it in the
+same refresh, kept from before while Blockscout fails. A read that fails keeps
+that token's previous entry, as a failed ETH balance keeps its figure, or takes
+Blockscout's entry from the same refresh when there is none. Every other token
+comes from the Blockscout `token-balances` response (`fetchTokenBalances()`), so
+tokens do appear without the user adding them, and they keep their previous
+figures while Blockscout fails.
+
+The refresh asks Blockscout only while the user has "Use Blockscout" on. The
+setting is off until the user turns it on. While it is off:
+
+- Only tracked tokens are listed. Turning the setting off drops every other
+  token from every address at once.
+- A tracked token's entry has no holder count and no `decimals` from Blockscout.
+- A tracked token's balance uses the decimals from the bundled list, or else the
+  decimals saved when the token was tracked.
+
+Blockscout may answer just before the user turns the setting off. So the popup's
+refresh and the background's both check the stored setting again when they save.
+If the setting is off by then, the save drops every token the user has not
+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. `fetchTokenBalances()` stores every nonzero holding of a token it
-admits, 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
+tracked. Every nonzero holding of a token shown is stored exactly, however
+small, but a holding below 0.000001 is left out of the balance lists, the
+send-screen token selector, the address total and the remove-address warning
+(`isBelowOneMillionth()` in `src/shared/amountDisplay.js`). The Send and
 confirmation screens show it when its token is the one being sent. Tracked
 tokens with a zero balance are listed as well while "Show tracked tokens with
 zero balance" is on.
@@ -1406,11 +1505,12 @@ wrote last, the record says which build's shape it is in.
 Each write reads the record, changes it and writes it back, holding a lock from
 the read to the write: the browser's own (`navigator.locks`), taken through
 `withLock()` in `src/shared/browserApi.js`. Every page of the extension and its
-background share it, except a page in a Firefox private window, which Firefox
-gives locks of its own (see https://git.eeqj.de/sneak/AutistMask/issues/646).
-The popup's `saveState()`, the background's `updateState()` and the
-StateRecovery reset all take it, so among the pages and the background that
-share it, no write lands between another write's read and its write, where it
+background share it, except a page in a Firefox private window, which has locks
+of its own. `manifest/firefox.json` sets `"incognito": "not_allowed"`, so such a
+page cannot read or write extension storage. In Chrome, a page opened from an
+incognito window still runs outside incognito and shares the lock. The popup's
+`saveState()`, the background's `updateState()` and the StateRecovery reset all
+take it, so no write lands between another write's read and its write, where it
 would be lost. Chrome has it from version 69, older than any Chrome that runs a
 Manifest V3 extension, in pages and in the service worker; Firefox from version
 96, older than the 115 `manifest/firefox.json` declares. Where it is missing, a
@@ -1564,20 +1664,41 @@ such as an edit typed into Settings and not yet saved. Home is the one screen
 "Back" always re-renders, so the wallet list reflects anything that changed
 while the user was away from it.
 
-A network switch in Settings leaves every screen beneath Settings showing the
-previous network, so after it "Back" behaves as in a reopened popup: every
-screen on the stack counts as not yet rendered, and the stack is cut at the
-first screen that cannot be rendered from saved state, such as Send or AddToken,
-or at AddressToken for any token but the native one, because that token was
-picked on the previous network. The cut stack is saved with the switch, so a
-popup closed straight after it and reopened onto Settings lands in the same
-place. "Back" then renders the screen it lands on for the new network, and
-anything typed there and not saved, which belonged to the previous network, is
-dropped. ConfirmTx, WaitTx, SuccessTx, ErrorTx and TransactionDetail are
-rendered instead for the network of the transaction they show: the network it
-was reviewed on for ConfirmTx, and the network it was sent on for the others.
-Without a wallet the stack is not cut, because it starts at Welcome, which shows
-nothing from a network.
+Changing "Use Blockscout" or "Check recipients on Etherscan" in Settings makes
+every screen but Settings count as not yet rendered. "Back" then renders again
+any screen that a reopened popup can render. A change to "Use Blockscout" also
+cuts the stack, as a network switch does (below). The cut drops Send, whose
+token dropdown was filled under the old setting. "Back" cannot render Send
+again. A change to "Check recipients on Etherscan" leaves the stack as it is.
+
+Any other open popup takes either change from the stored record, as it takes a
+network switch (below). That popup then redraws its top screen as a reopened
+popup would. A screen that a reopened popup cannot render, such as Send, is
+replaced by Home.
+
+A network switch leaves every screen on the page showing the previous network.
+The user makes it in Settings, or approves a site's request and the background
+saves it. Any other popup open meanwhile takes the switch from the stored
+record, even one saved while it was opening, and never switches the network
+itself. A switch the user picks in its Settings while it takes one is made after
+it, not overwritten by it. An approval window does not take the switch. After
+the switch, whichever way the page got it, "Back" behaves as in a reopened
+popup: every screen on the stack counts as not yet rendered, and the stack is
+cut at the first screen that cannot be rendered from saved state, such as Send
+or AddToken, or at AddressToken for any token but the native one, because that
+token was picked on the previous network and is no longer selected. The cut
+stack is saved with the popup's new network, so a popup closed straight after
+and reopened lands in the same place. The screen on top is drawn again for the
+new network: Settings in place, and any other screen as a reopened popup draws
+it, so Home takes the place of one that cannot be rendered from saved state or
+of AddressToken for a token no longer selected. "Back" then renders the screen
+it lands on for the new network, and anything typed there and not saved, which
+belonged to the previous network, is dropped. ConfirmTx, WaitTx, SuccessTx,
+ErrorTx and TransactionDetail are rendered instead for the network of the
+transaction they show: the network it was reviewed on for ConfirmTx, and the
+network it was sent on for the others. Without a wallet the stack is not cut and
+only Settings is drawn again, because the stack starts at Welcome, and Welcome
+and AddWallet show nothing from a network.
 
 Every screen that holds secret material in the page registers a cleanup with
 `onViewLeave()` (`src/popup/views/helpers.js`), which `showView()` runs on every
@@ -1596,8 +1717,17 @@ view would leave a wallet one click from deletion.
   screen in that case.
 - **Elements**:
     - "Welcome! To get started, add a wallet." text
+    - A well opening with "This wallet sends your data only to the Ethereum RPC
+      endpoint, unless you turn on one of these. You can change them later in
+      Settings."
+    - In the well, the "Use Blockscout" and "Check recipients on Etherscan"
+      checkboxes, the same two as in Settings. Under each, a sentence says what
+      the setting sends and to which service. Both are unticked until the user
+      ticks them
     - "Add wallet" button
 - **Transitions**:
+    - Ticking or unticking either checkbox → stores the setting, as Settings
+      does (no screen change)
     - "Add wallet" → **AddWallet**
 
 #### Home (`main`)
@@ -1618,6 +1748,8 @@ view would leave a wallet one click from deletion.
       holding more than one address); the ENS name, if resolved, is below it;
       then the full address on a row of its own, followed by the address USD
       total and a balance line for ETH and for each token shown for that address
+    - While "Use Blockscout" is off, a line under the wallet list: "Only tracked
+      tokens are listed, because "Use Blockscout" is off in Settings."
     - "Recent Transactions": up to 25 transactions merged across every address
       of every wallet, deduplicated by hash and filtered. Each row is three
       lines: age and direction, then the counterparty's colour dot (with our own
@@ -1625,7 +1757,11 @@ view would leave a wallet one click from deletion.
       counterparty's full address on a row of its own. A contract creation has
       no counterparty: its second line is the amount alone and its third line
       says "This transaction creates a new contract. It has no recipient." The
-      transaction lists on AddressDetail and AddressToken draw the same rows
+      transaction lists on AddressDetail and AddressToken draw the same rows.
+      The history comes from Blockscout. While "Use Blockscout" is off,
+      Blockscout is not asked. This list then shows only the line "No
+      transaction history is shown, because "Use Blockscout" is off in
+      Settings."
     - "Add additional wallet..." link at bottom
 - **Transitions**:
     - Tap address row → sets the active address and broadcasts
@@ -1663,18 +1799,20 @@ view would leave a wallet one click from deletion.
       without it, the lost-password route on DeleteWallet is the first they
       would hear of it. The hint line reserves its height, so switching tabs
       cannot move the password fields under the pointer.
+    - The password needs at least 12 characters. With "Allow weak passwords"
+      ticked in Settings, one character is enough.
     - "Import" button, with the error line beside it so that it adds no height
       to a screen whose button already starts near the bottom of the popup
 - **Transitions**:
-    - "Import" with a valid entry and a matching password of at least 12
-      characters → creates the wallet, clears the navigation stack, and →
-      **Home**. When no address is active yet, as on the first wallet, the new
-      wallet's first address becomes the active one. The phrase and xprv modes
-      then scan for further used addresses and report the count as a flash
-      message. When the scan finds two or more used addresses, they replace the
-      wallet's list, which then holds the first address only if it was used. If
-      the first address was active and is not in the new list, the new list's
-      first address becomes the active one and `AUTISTMASK_ACTIVE_CHANGED` is
+    - "Import" with a valid entry and a matching password that is long enough →
+      creates the wallet, clears the navigation stack, and → **Home**. When no
+      address is active yet, as on the first wallet, the new wallet's first
+      address becomes the active one. The phrase and xprv modes then scan for
+      further used addresses and report the count as a flash message. When the
+      scan finds two or more used addresses, they replace the wallet's list,
+      which then holds the first address only if it was used. If the first
+      address was active and is not in the new list, the new list's first
+      address becomes the active one and `AUTISTMASK_ACTIVE_CHANGED` is
       broadcast.
     - "Import" with a missing, short or mismatched password → full-sentence
       error on the error line, no screen change
@@ -1694,9 +1832,13 @@ view would leave a wallet one click from deletion.
     - USD total for address (see [Partial USD totals](#partial-usd-totals))
     - Balance list: ETH + the ERC-20 tokens shown for this address (4 decimal
       places, USD inline). Each balance row is clickable → **AddressToken**
+    - While "Use Blockscout" is off, a line under the balance list: "Only
+      tracked tokens are listed, because "Use Blockscout" is off in Settings."
     - Send / Receive / + Token buttons and a "···" menu button
     - "···" dropdown containing a single "Export Private Key" entry
-    - Transaction list (with ENS resolution for counterparties)
+    - Transaction list (with ENS resolution for counterparties). While "Use
+      Blockscout" is off, it shows only the line "No transaction history is
+      shown, because "Use Blockscout" is off in Settings."
 - **Transitions**:
     - Tap balance row → **AddressToken** (for that token)
     - "Send" → **Send** (refuses with a flash message on a zero balance)
@@ -1764,9 +1906,13 @@ view would leave a wallet one click from deletion.
     - Token contract well (ERC-20 only): full contract address (tap to copy,
       etherscan link) plus name, symbol, decimals, holder count and project
       website where known. The "Holders:" row is left out, not shown as 0, when
-      the token's balance-list entry has no holder count: the explorer did not
-      report a readable one, or the token is not in the balance list
-    - Token-filtered transaction list (only this token's transfers)
+      the token's balance-list entry has no holder count. That happens when:
+        - the explorer did not report a readable one
+        - "Use Blockscout" is off
+        - the token is not in the balance list
+    - Token-filtered transaction list (only this token's transfers). While "Use
+      Blockscout" is off, it shows only the line "No transaction history is
+      shown, because "Use Blockscout" is off in Settings."
 - **Transitions**:
     - "Send" → **Send** (token locked: the dropdown is replaced by a static
       symbol and contract address)
@@ -1783,6 +1929,9 @@ view would leave a wallet one click from deletion.
     - From: address with color dot + etherscan link
     - What to send: token dropdown (or static display with contract address when
       locked from AddressToken)
+    - While "Use Blockscout" is off, a line under the token dropdown: "Only
+      tracked tokens are listed, because "Use Blockscout" is off in Settings."
+      The line is hidden with the dropdown when Send is opened from AddressToken
     - To: address or ENS name input, with an inline validation message
     - Amount input with current balance display, which reads
       `Current balance: unknown (SYMBOL)` for a token whose scale is unknown, as
@@ -1802,13 +1951,14 @@ view would leave a wallet one click from deletion.
 - **Transitions**:
     - "Review" (valid inputs, ENS resolved) → **ConfirmTx**
     - "Review" with an unresolvable ENS name or an invalid amount → flash
-      message, no screen change. An amount is valid when it is a number above
-      zero, written as digits with at most one decimal point, with nothing but
-      zeros after the token's last decimal place. ETH has 18 places, and a token
-      with more, or with an unknown number, is held to 18. Zeros past those
-      places leave the amount unchanged, so `1.0000000` of a 6-place token
-      passes and is sent as exactly 1. ConfirmTx makes the same check before
-      anything can be sent
+      message, no screen change. A name with no address, or one resolved
+      off-chain, gets "That ENS name has no on-chain address." An amount is
+      valid when it is a number above zero, written as digits with at most one
+      decimal point, with nothing but zeros after the token's last decimal
+      place. ETH has 18 places, and a token with more, or with an unknown
+      number, is held to 18. Zeros past those places leave the amount unchanged,
+      so `1.0000000` of a 6-place token passes and is sent as exactly 1.
+      ConfirmTx makes the same check before anything can be sent
     - "Back" → previous screen (Home, AddressDetail, or AddressToken)
 
 #### ConfirmTx (`confirm-tx`)
@@ -1852,7 +2002,12 @@ view would leave a wallet one click from deletion.
       recipient that has never sent a transaction and holds no ETH, recipient is
       a contract, burn address, and an Etherscan phishing/scam label. An address
       that has received ETH but never sent a transaction still holds that ETH,
-      so it gets no warning
+      so it gets no warning. The Etherscan label check is made only while "Check
+      recipients on Etherscan" is on. While the setting is off, the Etherscan
+      box is left out. A line in its place says "This address was not checked on
+      Etherscan, because "Check recipients on Etherscan" is off in Settings."
+      The box or the line is chosen when the screen is drawn, so neither moves
+      anything later
     - Errors (an invalid amount), plus five reserved error boxes, so the balance
       and the fee arriving later move nothing — the amount exceeds the balance
       (for a token whose scale is unknown it says the token's balance is
@@ -1929,6 +2084,9 @@ view would leave a wallet one click from deletion.
       `Unknown (could not be decoded)` with no symbol, not the transaction's ETH
       value. When that swap's `Token In` is `ETH (native)`, the transaction's
       ETH value in the network's currency, as for any other transaction
+    - A line under the amount, worded as on TxApproval. While "Use Blockscout"
+      is off, the line shows when the bundled list and the tracked tokens lack
+      the token's name or decimals.
     - To: color dot + full address + etherscan link; for a contract creation,
       which has no recipient, "This transaction creates a new contract. It has
       no recipient." instead
@@ -1961,7 +2119,9 @@ view would leave a wallet one click from deletion.
 - **Elements**:
     - "Transaction Confirmed" heading
     - Decoded action well (shown when the transaction carried recognized
-      calldata; the top-level Amount and To are hidden in that case)
+      calldata; the top-level Amount and To are hidden in that case). Each token
+      in the well gets TxApproval's line under it whenever TxApproval would show
+      that line.
     - Amount + symbol
     - To: color dot + full address + etherscan link, or for a contract creation
       the same sentence as on WaitTx
@@ -1984,6 +2144,8 @@ view would leave a wallet one click from deletion.
     - Amount + symbol, or for a swap the approval screen showed no `Amount` for,
       the same as on WaitTx: `Unknown (could not be decoded)`, unless its
       `Token In` is `ETH (native)`
+    - The same line under the amount as on WaitTx, whenever WaitTx would show
+      it.
     - To: color dot + full address + etherscan link, or for a contract creation
       the same sentence as on WaitTx
     - Error message (dashed border box)
@@ -2018,7 +2180,11 @@ view would leave a wallet one click from deletion.
   AddressToken. The screen describes the transaction on the network it was sent
   on, whichever network is active: its block, network details, decoded details
   and raw data are read from that network's Blockscout, the one Settings has for
-  it, and its etherscan links open that network's explorer.
+  it, and its etherscan links open that network's explorer. While "Use
+  Blockscout" is off, Blockscout is not asked. One line then takes the place of
+  the block, network details, decoded details and raw data: "This screen shows
+  no block, decoded details, network details or raw data, because "Use
+  Blockscout" is off in Settings."
 - **Elements** (grouped into logical blocks using light well containers; field
   labels are self-explanatory so groups have no headings):
     - "Transaction" heading, "Back" button
@@ -2083,6 +2249,10 @@ view would leave a wallet one click from deletion.
     - Wallets: one row per wallet with its name (tap to rename inline), a
       `[recovery phrase]` button on HD wallets only, and an `[x]` delete button,
       plus a "+ Add wallet" button
+    - Passwords:
+        - "Allow weak passwords" checkbox, unticked until the user ticks it
+        - A sentence saying the setting lets the user choose a password shorter
+          than 12 characters on AddWallet
     - Tracked Tokens: one row per token tracked on the active network with an
       `[x]` remove button, plus a "+ Add token" button
     - Display: "Show tracked tokens with zero balance" checkbox, "UTC
@@ -2101,8 +2271,21 @@ view would leave a wallet one click from deletion.
       already active changes nothing and sends nothing
     - Ethereum RPC: endpoint URL input + "Save" button (validated against
       `eth_chainId` before being saved)
-    - Blockscout API: endpoint URL input + "Save" button (validated against
-      `/stats` before being saved)
+    - Blockscout API:
+        - "Use Blockscout" checkbox, unticked until the user ticks it
+        - A sentence saying what the setting shows and what it sends. With the
+          setting on, the wallet sends the Blockscout API the user's addresses
+          and the hash of each transaction opened
+        - 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.
+    - Etherscan:
+        - "Check recipients on Etherscan" checkbox, unticked until the user
+          ticks it
+        - A sentence saying the setting sends each recipient's address to
+          Etherscan, to check the address for a phishing or scam label
+    - Each of the two settings applies to every network. Welcome offers the same
+      two checkboxes
     - Token Spam Protection:
         - "Hide fake tokens impersonating a known symbol" checkbox
         - "Hide tokens with fewer than 1,000 holders" checkbox
@@ -2126,6 +2309,10 @@ view would leave a wallet one click from deletion.
     - Debug: hidden until revealed, then an "Enable debug mode" checkbox that
       turns on the red banner and verbose logging
 - **Transitions**:
+    - Ticking or unticking "Use Blockscout" or "Check recipients on Etherscan" →
+      stores the setting (no screen change). From then on, every screen drawn
+      and every balance refresh uses the new setting. Unticking "Use Blockscout"
+      also drops every token the user has not tracked from every address
     - "+ Add wallet" → **AddWallet**
     - "+ Add token" → **SettingsAddToken**
     - `[recovery phrase]` on an HD wallet → **ShowRecoveryPhrase**
@@ -2144,7 +2331,8 @@ view would leave a wallet one click from deletion.
       nothing and tells the background nothing
     - Ten clicks on the version → reveals the Debug well (no screen change)
     - "Back" (or Settings gear again) → previous screen (Home); after a network
-      switch, the stack is cut first (see the top of Screen Map)
+      switch or a change to "Use Blockscout", the stack is cut first (see the
+      top of Screen Map)
 
 #### ShowRecoveryPhrase (`show-phrase`)
 
@@ -2301,6 +2489,8 @@ view would leave a wallet one click from deletion.
       money. The predicate is `addressHoldsFunds()` in
       `src/popup/views/helpers.js`, unrounded and token-aware. A balance is a
       warning, never a refusal.
+    - While "Use Blockscout" is off, a line under the warning: "Only tracked
+      tokens are listed, because "Use Blockscout" is off in Settings."
     - The rule that a wallet always keeps at least one address, and that
       removing the last one means deleting the wallet from Settings
     - Error line
@@ -2433,6 +2623,12 @@ view would leave a wallet one click from deletion.
       a swap pays only the From address, a `Paid to` line for each other address
       it pays, or saying that a token stays in the router or who it pays is
       unknown (see Transaction Decoding)
+    - A line under each token of the decoded action: "Blockscout's report of
+      your balances is not used to name this token, because "Use Blockscout" is
+      off in Settings." While "Use Blockscout" is off, the line shows when the
+      bundled list and the tracked tokens lack the token's name or decimals.
+      While the setting is on, Blockscout's report of the user's balances is a
+      third source of a token's name and decimals (see Unknown token scale).
     - From: color dot + full address + etherscan link
     - Contract: color dot + full address + etherscan link, token symbol label if
       known; for a contract creation, the same sentence as on WaitTx
@@ -2459,8 +2655,14 @@ view would leave a wallet one click from deletion.
       Data Model) → full-sentence error on the error line saying why, nothing
       signed (no screen change)
     - "Reject" → closes popup (returns rejection to background)
-    - Popup window closed without answering → the request is rejected with
-      EIP-1193 code 4001
+    - "Reject" after "Confirm", while the transaction is being sent → the
+      background's message on the error line, no screen change
+    - Popup window closed without answering → the request stays pending, and the
+      site gets no answer. The browser can close this window when the user
+      clicks away from it, for example to copy the password from a password
+      manager. Until the request is answered, the toolbar button opens this
+      screen instead of the wallet. When several requests wait with their
+      windows closed, the toolbar button opens the oldest first.
 
 #### SignApproval (`approve-sign`)
 
@@ -2512,7 +2714,10 @@ view would leave a wallet one click from deletion.
       the site puts in the message, except a `Permit`'s token, which is the
       domain's `verifyingContract`; any those fields do not give is shown as
       `Unknown`, and the domain, type and message lines still follow. Only typed
-      data that cannot be read at all is shown as raw text.
+      data that cannot be read at all is shown as raw text. A token gets the
+      same line under it as on TxApproval, whenever TxApproval would show that
+      line. As there, Blockscout's report of the user's balances is a source of
+      a token's name and decimals only while "Use Blockscout" is on.
     - Raw data (`personal_sign` and `eth_sign`): the message's hex exactly as
       the site sent it. The bytes it encodes are what is signed, as an EIP-191
       personal message.
@@ -2546,8 +2751,11 @@ view would leave a wallet one click from deletion.
     - "Sign" (wrong password, or a signing failure) → error line, no screen
       change
     - "Reject" → closes popup (returns rejection to background)
-    - Popup window closed without answering → the request is rejected with
-      EIP-1193 code 4001
+    - "Reject" after "Sign", while the signature is being checked → the
+      background's message on the error line, no screen change
+    - Popup window closed without answering → the request stays pending, as on
+      TxApproval. Until the request is answered, the toolbar button opens this
+      screen instead of the wallet.
 
 #### NetworkApproval (`approve-network`)
 
@@ -2642,16 +2850,36 @@ view would leave a wallet one click from deletion.
 
 ### External Services
 
-AutistMask is not a fully self-contained offline tool. It necessarily
-communicates with three external services to function as a wallet:
+AutistMask is not a fully self-contained offline tool. By default it sends the
+user's data only to the Ethereum RPC endpoint. It also asks the CoinDesk price
+API for prices, sending token symbols and nothing else.
+
+Two more services are sent none of the user's data until the user turns on a
+setting for each:
+
+- Blockscout, with "Use Blockscout"
+- Etherscan, with "Check recipients on Etherscan"
+
+Both settings are off in a new install. Welcome and Settings both offer them.
+Each setting applies to every network.
+
+Before each request that sends the user's data to Blockscout or Etherscan, the
+wallet reads that service's setting from storage. The wallet reads the setting
+again when the answer lands. While the setting is off, no such request is made,
+and an answer that lands after the setting went off is dropped.
+
+Contacted by default:
 
 - **Ethereum JSON-RPC endpoint**: The extension needs an Ethereum node to query
-  balances (`eth_getBalance`), read ERC-20 token contracts (`eth_call`),
+  balances (`eth_getBalance`), read ERC-20 token contracts (`eth_call`), among
+  them the balance of every tracked token at every address (`balanceOf`),
   estimate gas (`eth_estimateGas`), fetch nonces (`eth_getTransactionCount`),
   broadcast transactions (`eth_sendRawTransaction`), and check transaction
-  receipts. The default endpoint is a public RPC (configurable by the user to
-  any endpoint they prefer, including a local node). By default the extension
-  talks to `https://ethereum-rpc.publicnode.com`.
+  receipts. Every ENS lookup is made through the RPC endpoint alone. So a name
+  does not resolve when its resolver says the name is resolved off-chain. The
+  default endpoint is a public RPC (configurable by the user to any endpoint
+  they prefer, including a local node). By default the extension talks to
+  `https://ethereum-rpc.publicnode.com`.
     - **Data sent**: Ethereum addresses, transaction data, contract call
       parameters. The RPC endpoint can see all on-chain queries and submitted
       transactions.
@@ -2663,13 +2891,44 @@ communicates with three external services to function as a wallet:
     - **Data sent**: Token symbol strings only (e.g. "ETH", "USDC"). No
       addresses or user-specific data.
 
-- **Blockscout block-explorer API**: Used to fetch transaction history (normal
-  transactions and ERC-20 token transfers), ERC-20 token balances, and token
-  holder counts (for spam filtering). The default endpoint is
+Sent the user's data only while its setting is on:
+
+- **Blockscout block-explorer API** ("Use Blockscout"): The default endpoint is
   `https://eth.blockscout.com/api/v2` (configurable by the user in Settings).
-    - **Data sent**: Ethereum addresses. Blockscout receives the user's
-      addresses to query their transaction history and token balances. No
-      private keys, passwords, or signing operations are sent.
+    - **Used for**:
+        - transaction history (normal transactions and ERC-20 token transfers),
+          for Home, AddressDetail and AddressToken
+        - the balances of the ERC-20 tokens the user has not tracked, for Home,
+          AddressDetail, Send and DeleteAddress
+        - the names and decimals of those tokens, for TxApproval, SignApproval,
+          WaitTx, SuccessTx and ErrorTx
+        - token holder counts, for spam filtering
+        - a transaction's block, network details and calldata, for
+          TransactionDetail
+    - **Contacted**, while the setting is on:
+        - on every balance refresh, in the popup and in the background
+        - when Home, AddressDetail or AddressToken loads its history
+        - when TransactionDetail opens
+    - **While the setting is off**: Each screen that would show Blockscout's
+      data says instead that the setting is off. Only tracked tokens are listed.
+    - **Saving the URL**: pressing "Save" beside the URL in Settings asks that
+      URL for `/stats`, whether or not the setting is on. This request carries
+      no user data.
+    - **Data sent**: Ethereum addresses, and the hash of each transaction the
+      user opens. Blockscout receives the user's addresses to query their
+      transaction history and token balances. No private keys, passwords, or
+      signing operations are sent.
+
+- **Etherscan address labels** ("Check recipients on Etherscan"): While the
+  setting is on, ConfirmTx looks up the recipient's address on Etherscan each
+  time the screen is shown. The lookup checks for a phishing or scam label,
+  best-effort. This is a direct page fetch with no API key; the user's browser
+  makes the request. While the setting is off, ConfirmTx says that no Etherscan
+  check was made.
+    - **Data sent**: the recipient's address and nothing else.
+
+The etherscan links on the screens open a page in the browser when the user
+clicks one. They are not requests the wallet makes.
 
 What the extension does NOT do:
 
@@ -2678,16 +2937,9 @@ What the extension does NOT do:
 - No Infura/Alchemy dependency (any JSON-RPC endpoint works)
 - No backend servers operated by the developer
 
-In addition to the three user-configurable services above (RPC endpoint,
-CoinDesk price API, and Blockscout API), AutistMask also contacts:
-
-- **Etherscan address labels**: When confirming a transaction, the extension
-  performs a best-effort lookup of the recipient address on Etherscan to check
-  for phishing/scam labels. This is a direct page fetch with no API key; the
-  user's browser makes the request.
-
-Users who want maximum privacy can point the RPC and Blockscout URLs at their
-own self-hosted instances (price fetching can be disabled in a future version).
+Users who want maximum privacy can point the RPC URL at their own node. With
+"Use Blockscout" on, they can point the Blockscout URL at their own instance
+too.
 
 ### Dependencies
 
@@ -2836,6 +3088,11 @@ logged.
     - The user's password is run through Argon2id (`crypto_pwhash`) to derive a
       256-bit encryption key. Argon2id is memory-hard, making GPU/ASIC brute
       force attacks expensive.
+    - Each use of the password runs one Argon2id derivation at libsodium's
+      interactive setting: `OPSLIMIT_INTERACTIVE` and `MEMLIMIT_INTERACTIVE`, 2
+      passes over 64 MiB. Every signature asks for the password, so a light
+      setting keeps signing quick. The password's length, not the derivation's
+      cost, is what protects the stored secret.
     - The derived key encrypts the secret material using XSalsa20-Poly1305
       (`crypto_secretbox`), which provides authenticated encryption (the
       ciphertext cannot be tampered with without detection).
@@ -2869,8 +3126,11 @@ logged.
 - Add multiple addresses within an HD wallet
 - Manage multiple wallets simultaneously
 - View ETH balance per address
-- View ERC-20 token balances (tokens on the bundled known-token list, tokens
-  with 1,000 or more holders, and tokens the user adds by contract address)
+- View ERC-20 token balances:
+    - tokens the user adds by contract address
+    - while "Use Blockscout" is on, tokens on the bundled known-token list and
+      tokens with 1,000 or more holders
+- View transaction history and transaction details, while "Use Blockscout" is on
 - Send ETH to an address
 - Send ERC-20 tokens to an address
 - Receive ETH/tokens (display address, copy to clipboard, QR code)
@@ -3185,8 +3445,9 @@ Currently supported:
   `Min. paid out`, because the swap's minimum includes the fee. The minimum
   reads `Min. received` only when some step pays the transaction's sender (the
   From address on TxApproval, the sender the explorer reports on
-  TransactionDetail) and no `Paid to` line is shown. `Paid to` lines after
-  `Token Out` name each other address paid; one reads
+  TransactionDetail), no `Paid to` line is shown, and no permit or batch grants
+  an allowance to a spender other than the router (see below). `Paid to` lines
+  after `Token Out` name each other address paid; one reads
   `The bridge, which pays the deposit's recipient on another network` for a
   bridge deposit; one reads, for example,
   `The router, 2000.0000 USDT from the sender (later steps may not spend all of it)`
@@ -3240,7 +3501,8 @@ Currently supported:
   (listed at the end of this section), a step whose input it cannot read, in
   whole or in part, and a step it fails on. Every other `PERMIT2_PERMIT`, before
   the step that sets the input side or after it, leaves `Token In` and the
-  `Amount` line as they read with no permit: a permit of 5,000 DAI to another
+  `Amount` line as they read with no permit, unless it lets a spender other than
+  the router take `Token In` (see below): a permit of 5,000 DAI to another
   address and then a V3 exact-in of 600 USDT read `Swap USDT → USDC` with
   `Amount 600.0000 USDT`, and so do that exact-in and then a permit of 5,000 DAI
   to the router. When a permit's amount stands and the step that sets the input
@@ -3254,26 +3516,30 @@ Currently supported:
   whose amount the decoder does not know. When there is no `Amount` line, each
   take the total counts gets them too, so that every amount the decoder reads is
   shown: the amount the step that sets the input side states, when it is a
-  quantity, and each later take of `Token In` added to it. A `PERMIT2_PERMIT`
-  the decoder cannot read, then V3 exact-ins of 600 USDT and 400 DAI paid by the
-  user, give lines for both amounts. When the step that sets the input side
-  states no amount, the user pays it some of its input token, and there is no
-  `Amount` line, that step gets them too whenever another take's lines give a
-  figure, or a `PERMIT2_TRANSFER_FROM` of its token gives one, on the lines
-  below or, into the router, on its `Paid to` line, so that figure cannot read
-  as all that leaves. When it states no amount and the user pays it none of its
-  input token, as when the router pays it, that step takes none of that token
-  from the user's wallet and never gets them, with a permit or without. They
-  come in step order, except that the step that sets the input side comes first
-  when it has them, followed, when there is no `Amount` line, by the other takes
-  the total counts: `Moved from the sender`, its amount, worded as the `Amount`
-  line words one, or `Unknown (could not be decoded)` when the decoder does not
-  know it; `Token moved`, giving the token's address as the `Token In` line
-  does; and `Moved to`, which reads `The swap step that spends it`. A token the
-  decoder does not know gives the `Moved from the sender` line alone. A step may
-  also take from the user's wallet what the decoder did not read: a V4 step
-  whose input or one of whose `SETTLE`s or `SETTLE_ALL`s it cannot read, which
-  the router still runs; a V2 or V3 exact-in or exact-out step or a
+  quantity and the user pays that step (a V2 or V3 step whose `payerIsUser` is
+  true, a V4 step the user pays some of its input token, or a `WRAP_ETH`, whose
+  ETH comes from the transaction's value), and each later take of `Token In`
+  added to it. A step that sets the input side and is paid from the router takes
+  nothing from the user's wallet and gets none. A `PERMIT2_PERMIT` the decoder
+  cannot read, then V3 exact-ins of 600 USDT and 400 DAI paid by the user, give
+  lines for both amounts. When the step that sets the input side states no
+  amount, the user pays it some of its input token, and there is no `Amount`
+  line, that step gets them too whenever another take's lines give a figure, or
+  a `PERMIT2_TRANSFER_FROM` of its token gives one, on the lines below or, into
+  the router, on its `Paid to` line, so that figure cannot read as all that
+  leaves. When it states no amount and the user pays it none of its input token,
+  as when the router pays it, that step takes none of that token from the user's
+  wallet and never gets them, with a permit or without. They come in step order,
+  except that the step that sets the input side comes first when it has them,
+  followed, when there is no `Amount` line, by the other takes the total counts:
+  `Moved from the sender`, its amount, worded as the `Amount` line words one, or
+  `Unknown (could not be decoded)` when the decoder does not know it;
+  `Token moved`, giving the token's address as the `Token In` line does; and
+  `Moved to`, which reads `The swap step that spends it`. A token the decoder
+  does not know gives the `Moved from the sender` line alone. A step may also
+  take from the user's wallet what the decoder did not read: a V4 step whose
+  input or one of whose `SETTLE`s or `SETTLE_ALL`s it cannot read, which the
+  router still runs; a V2 or V3 exact-in or exact-out step or a
   `PERMIT2_TRANSFER_FROM` whose input it cannot read, such as a V3 step whose
   path is shorter than one token address or has bytes after its last hop; every
   `PERMIT2_TRANSFER_FROM_BATCH`; every `EXECUTE_SUB_PLAN`, wherever it stands;
@@ -3303,19 +3569,26 @@ Currently supported:
   `PERMIT2_PERMIT` or `PERMIT2_PERMIT_BATCH` whose input the decoder cannot
   read, such as one whose token or spender word has a nonzero top byte, may let
   any spender take any amount of any token: it gives one `Permit2 allowance`
-  line alone, reading `Unknown (could not be decoded)`, and leaves no `Amount`
-  line, whose figure might be too low. These lines change neither the `Paid to`
-  lines nor the minimum's label: a permit or batch pays nobody. A step goes
-  unread when its recipient does not decode as an address, when it is a V3 swap
-  step whose path is shorter than one token address or has bytes after its last
-  hop, or when it is a command the decoder does not read: every command other
-  than `PERMIT2_PERMIT`, `PERMIT2_PERMIT_BATCH`, `PERMIT2_TRANSFER_FROM`,
-  `V2_SWAP_EXACT_IN`, `V2_SWAP_EXACT_OUT`, `V3_SWAP_EXACT_IN`,
-  `V3_SWAP_EXACT_OUT`, `V4_SWAP`, `SWEEP`, `TRANSFER`, `PAY_PORTION`,
-  `PAY_PORTION_FULL_PRECISION`, `ACROSS_V4_DEPOSIT_V3`, `WRAP_ETH`,
-  `UNWRAP_WETH` and `BALANCE_CHECK_ERC20` (`PERMIT2_TRANSFER_FROM_BATCH`,
-  `EXECUTE_SUB_PLAN` and the NFT commands among them), or a type its release
-  names no command for.
+  line alone, reading `Unknown (could not be decoded)`. These lines change no
+  `Paid to` line: a permit or batch pays nobody. But code that a step runs, such
+  as a V4 pool's hook or a token's own code, can call a spender other than the
+  router, which can then take up to its allowance from the user's wallet before
+  the transaction ends. So an allowance to any spender but the router, or a
+  permit or batch the decoder cannot read, makes the minimum read
+  `Min. paid out`, and when its token is `Token In`, or the decoder does not
+  know its token or `Token In`, it leaves no `Amount` line, whose figure might
+  be too low: a permit of 5,000 USDT to another address and then a V3 exact-in
+  of 600 USDT read with no `Amount` line, and the 600 USDT gets lines of its
+  own. A step goes unread when its recipient does not decode as an address, when
+  it is a V3 swap step whose path is shorter than one token address or has bytes
+  after its last hop, or when it is a command the decoder does not read: every
+  command other than `PERMIT2_PERMIT`, `PERMIT2_PERMIT_BATCH`,
+  `PERMIT2_TRANSFER_FROM`, `V2_SWAP_EXACT_IN`, `V2_SWAP_EXACT_OUT`,
+  `V3_SWAP_EXACT_IN`, `V3_SWAP_EXACT_OUT`, `V4_SWAP`, `SWEEP`, `TRANSFER`,
+  `PAY_PORTION`, `PAY_PORTION_FULL_PRECISION`, `ACROSS_V4_DEPOSIT_V3`,
+  `WRAP_ETH`, `UNWRAP_WETH` and `BALANCE_CHECK_ERC20`
+  (`PERMIT2_TRANSFER_FROM_BATCH`, `EXECUTE_SUB_PLAN` and the NFT commands among
+  them), or a type its release names no command for.
 
 ### Non-Goals Forever
 

docs/README.md

@@ -57,11 +57,12 @@ analytics, use a portfolio tracker. The wallet is not the place for any of that.
 
 - **No NFT galleries or portfolio views.** This is a wallet, not a dashboard.
 
-- **No third-party token list APIs.** Token balances come from the same block
-  explorer you configure for transaction history, and the extension ships its
-  own hardcoded list of top ERC-20 contract addresses for symbol-spoofing
-  detection. Any token you want tracked across all your addresses, you add
-  yourself by contract address.
+- **No third-party token list APIs.** The balances of the tokens you track are
+  read from your RPC endpoint. While "Use Blockscout" is on, the other tokens
+  come from the same block explorer you configure for transaction history. The
+  extension ships its own hardcoded list of top ERC-20 contract addresses for
+  symbol-spoofing detection. Any token you want tracked across all your
+  addresses, you add yourself by contract address.
 
 - **No backend servers operated by the developer.** Nothing is sent to any
   server run by AutistMask. Every network destination is listed below.
@@ -69,8 +70,13 @@ analytics, use a portfolio tracker. The wallet is not the place for any of that.
 ## How It Works
 
 AutistMask is a browser extension that runs entirely in your browser. It does
-not have a backend server. It communicates with five external destinations:
-three you configure yourself, and two fixed ones used for scam detection.
+not have a backend server. Out of the box it sends your data only to the
+Ethereum RPC endpoint. It also asks the CoinDesk price API for prices, sending
+token symbols and nothing else.
+
+Blockscout and Etherscan are sent none of your data until you turn on a setting
+for each. The settings are "Use Blockscout" and "Check recipients on Etherscan".
+Both are off in a new install. Welcome and Settings both offer them.
 
 ### External Services
 
@@ -83,11 +89,14 @@ verify confirmations. The default is a free public RPC endpoint. You can change
 this in Settings to any Ethereum JSON-RPC endpoint, including your own local
 node.
 
-When it is contacted: on every balance refresh (every 10 seconds while the popup
-is open, every 60 seconds in the background), when you type an ENS name into the
-Send screen, when a send is prepared and broadcast, while a pending transaction
-is polled for its receipt, and for the reverse ENS lookups used to label
-addresses (cached for 12 hours).
+When it is contacted:
+
+- on every balance refresh (every 10 seconds while the popup is open, every 60
+  seconds in the background)
+- when you review a send to an ENS name
+- when a send is prepared and broadcast
+- while a pending transaction is polled for its receipt
+- for the reverse ENS lookups used to label addresses (cached for 12 hours)
 
 What gets sent: standard Ethereum JSON-RPC requests (balance queries,
 transaction broadcasts, gas estimates, ENS lookups, contract-code checks). Your
@@ -96,16 +105,31 @@ addresses are necessarily visible to the RPC provider when querying balances.
 **Blockscout API** (default: `eth.blockscout.com/api/v2`;
 `eth-sepolia.blockscout.com/api/v2` on Sepolia)
 
-Used to fetch token balances and transaction history. Blockscout is an
-open-source blockchain explorer. AutistMask queries it for your ERC-20 token
-balances (including the holder counts used for spam filtering) and your recent
-transactions and token transfers. You can change this in Settings to a
-self-hosted Blockscout instance.
+Blockscout is an open-source blockchain explorer. AutistMask sends it your data
+only while "Use Blockscout" is on. AutistMask then asks Blockscout for:
 
-When it is contacted: on every balance refresh, and whenever a screen showing
-transaction history is opened.
+- your recent transactions and token transfers
+- the balances of the tokens you have not tracked, with the holder counts used
+  for spam filtering
+- the block, fees and calldata of a transaction you open
 
-What gets sent: your Ethereum addresses (to look up balances and transactions).
+You can change the endpoint in Settings to a self-hosted Blockscout instance.
+While the setting is off, each screen that would show Blockscout's data says
+instead that the setting is off. Only the tokens you track are listed. When you
+turn the setting off, every other token leaves the lists at once.
+
+When it is contacted, while "Use Blockscout" is on:
+
+- on every balance refresh
+- whenever a screen showing transaction history is opened
+- when you open a transaction
+
+Pressing "Save" beside the Blockscout URL in Settings checks the URL by asking
+it for `/stats`. That happens whether or not the setting is on. The request
+sends none of your data.
+
+What gets sent: your Ethereum addresses (to look up balances and transactions)
+and the hash of each transaction you open.
 
 **CoinDesk CADLI price API** (`data-api.coindesk.com`)
 
@@ -122,16 +146,21 @@ address.
 
 **Etherscan address labels** (`etherscan.io`; `sepolia.etherscan.io` on Sepolia)
 
-When you review a send, AutistMask fetches the recipient's public Etherscan
-address page and looks for a "Fake_Phishing"/"Phish/Hack" label or a scam
-warning, and shows a red warning if it finds one. This is a plain page fetch
-with no API key, made by your browser. It is best-effort: if it fails, it is
-silently ignored. This endpoint is not user-configurable.
+While "Check recipients on Etherscan" is on, AutistMask fetches the recipient's
+public Etherscan address page when you review a send. AutistMask looks for a
+"Fake_Phishing"/"Phish/Hack" label or a scam warning, and shows a red warning if
+it finds one. This is a plain page fetch with no API key, made by your browser.
+It is best-effort: if it fails, it is silently ignored. This endpoint is not
+user-configurable.
 
-When it is contacted: each time you reach the send confirmation screen.
+The setting is off in a new install. While it is off, the confirmation screen
+says that no Etherscan check was made.
 
-What gets sent: the recipient address you are about to send to, and your IP
-address. Your own addresses are not sent.
+When it is contacted: only while "Check recipients on Etherscan" is on, each
+time you reach the send confirmation screen.
+
+What gets sent: the recipient's address and nothing else. As with any request,
+Etherscan sees your IP address.
 
 Etherscan links shown elsewhere in the UI (on addresses, transactions, and token
 contracts) are ordinary links. They contact nothing until you click them.
@@ -179,12 +208,18 @@ password.
 3. Click "Load Temporary Add-on".
 4. Select `dist/firefox/manifest.json`.
 
+AutistMask does not work in Firefox private windows. If Firefox is set to "Never
+remember history", every window is private, so AutistMask does not work at all.
+
 ## Getting Started
 
 ### Creating a New Wallet
 
 1. Click the AutistMask icon in your browser toolbar.
 2. Click "Add wallet" (on first use), or open Settings and click "+ Add wallet".
+   On first use, the screen with "Add wallet" also offers "Use Blockscout" and
+   "Check recipients on Etherscan", both off. External Services above says what
+   each one does. You can change both later in Settings.
 3. On the "From Phrase" tab, click the die button to generate a random 12-word
    recovery phrase.
 4. **Write down the recovery phrase and store it safely.** Anyone with these
@@ -220,10 +255,14 @@ always produce the same sequence of addresses.
 
 ### Adding ERC-20 Tokens
 
-Tokens you hold show up automatically only if they are in the extension's
-bundled list of well-known tokens or have at least 1,000 holders; everything
-else is treated as spam and hidden. To track a token explicitly (which also
-shows it at zero balance), add it by contract address:
+The wallet looks for tokens you hold only while "Use Blockscout" is on. Even
+then, a token shows up only if it is in the extension's bundled list of
+well-known tokens or has at least 1,000 holders. Everything else is treated as
+spam and hidden.
+
+The wallet shows every token you track, whether or not "Use Blockscout" is on.
+By default a tracked token is shown at zero balance too (see Display in
+Settings). To track a token, add it by contract address:
 
 1. Go to an address detail view (click `[info]` on any address).
 2. Click "+ Token".
@@ -237,9 +276,12 @@ screen. Tokens can also be added from Settings, under "Tracked Tokens".
 ## Sending
 
 1. Click "Send" from the home screen or an address detail view.
-2. Select what to send (ETH, or any ERC-20 token with a balance on this address
-   that survives the spam filters).
-3. Enter the recipient address or ENS name (e.g. `vitalik.eth`).
+2. Select what to send: ETH, or a token you track that this address holds. While
+   "Use Blockscout" is on, Send also offers other tokens with a balance on this
+   address that survive the spam filters.
+3. Enter the recipient address or ENS name (e.g. `vitalik.eth`). AutistMask does
+   not look up a name resolved off-chain. For such a name, enter the address
+   instead.
 4. Enter the amount, or click "Max" to fill it in: a token's balance, cut to 18
    decimal places, or your ETH balance minus the amount reserved for the network
    fee.
@@ -256,9 +298,13 @@ The confirmation screen shows:
   estimate, and below it the larger amount reserved until it confirms. The
   reserve is what the network requires up front and what the balance check gates
   on; the refund of the difference is why the two differ
-- **Warnings** if the recipient is a contract, a burn address, one of your own
-  addresses, on the bundled scam-address list, or labelled as a phisher on
-  Etherscan
+- **Warnings** if the recipient is:
+    - a contract
+    - a burn address
+    - one of your own addresses
+    - on the bundled scam-address list
+    - while "Check recipients on Etherscan" is on, labelled as a phisher on
+      Etherscan
 
 After reviewing, enter your password and click "Sign & Send". The transaction
 will be broadcast to the network and you will see a waiting screen with a timer.
@@ -269,8 +315,9 @@ screen with the transaction hash and an Etherscan link.
 
 You can also send from a token-specific view: on the address detail screen,
 click any token balance row. This opens a focused view showing only that token's
-transactions. Clicking "Send" from here pre-selects and locks the token so you
-cannot accidentally switch to a different one.
+transactions. While "Use Blockscout" is off, the view says instead that no
+transaction history is shown. Clicking "Send" from here pre-selects and locks
+the token so you cannot accidentally switch to a different one.
 
 ## Receiving
 
@@ -306,6 +353,13 @@ enter your password and click "Confirm" to authorize it. Message and typed-data
 signature requests work the same way, with a "Sign" button, and also require
 your password.
 
+If a transaction or signature popup closes before you answer, for example when
+you click away to copy your password, the request stays open. Closing the popup
+does not turn the request down. Click the AutistMask icon in your browser
+toolbar to bring the request back. Until you answer, the icon opens the request
+instead of your wallet. If several requests are waiting this way, the oldest
+comes first.
+
 A connected site can also ask to switch the wallet's network. A popup shows the
 site's origin, the current network and the requested network. Nothing changes
 unless you click "Switch"; clicking "Reject" or closing the popup leaves
@@ -344,11 +398,12 @@ balances unless they are on the bundled known-token list or you added them
 yourself. Legitimate tokens have substantial holder counts; scam tokens deployed
 for address poisoning typically have zero. When the explorer reports no holder
 count for a token, or reports something other than a whole number in plain
-digits (such as "1,000"), the count is unknown. An unknown count does not hide a
-token from your transaction history or the send token list, and it does not get
-a token into your balances either: such a token is listed only if it is on the
-bundled known-token list or you added it yourself. The screen you reach by
-clicking a token balance shows a "Holders:" line only when the count is known.
+digits (such as "1,000"), the count is unknown. While "Use Blockscout" is off,
+no holder count is known. An unknown count does not hide a token from your
+transaction history or the send token list, and it does not get a token into
+your balances either: such a token is listed only if it is on the bundled
+known-token list or you added it yourself. The screen you reach by clicking a
+token balance shows a "Holders:" line only when the count is known.
 
 **Fraud contract blocklist.** When AutistMask detects a fraudulent transfer, it
 adds the contract address to a local blocklist. Future transactions from that
@@ -380,6 +435,8 @@ see everything unfiltered.
 Click the gear icon on the home screen to access settings:
 
 - **Wallets**: Your wallets, and "+ Add wallet".
+- **Passwords**: Tick "Allow weak passwords" to choose a password shorter than
+  12 characters when you add a wallet.
 - **Tracked Tokens**: The ERC-20 tokens tracked across all addresses, and "+ Add
   token".
 - **Display**: Toggle whether tracked tokens with zero balance are shown, switch
@@ -389,8 +446,9 @@ Click the gear icon on the home screen to access settings:
   that network's defaults if you have not used it before.
 - **Ethereum RPC**: Change the Ethereum node endpoint. Default is a public RPC.
   You can use your own node for maximum privacy.
-- **Blockscout API**: Change the Blockscout instance used for token balances and
-  transaction history. You can use a self-hosted instance.
+- **Blockscout API**: the "Use Blockscout" checkbox, off until you tick it, and
+  the URL of the Blockscout instance. You can use a self-hosted instance.
+- **Etherscan**: "Check recipients on Etherscan", off until you tick it.
 - **Token Spam Protection**: Toggle individual scam filters and set the dust
   transaction threshold.
 - **Allowed Sites / Denied Sites**: View and manage web3 site permissions.

manifest/firefox.json

@@ -4,6 +4,7 @@
     "version": "0.1.0",
     "description": "Minimal Ethereum wallet for Firefox",
     "permissions": ["storage", "activeTab", "alarms", "<all_urls>"],
+    "incognito": "not_allowed",
     "content_security_policy": "default-src 'self'; script-src 'self' 'wasm-unsafe-eval'; object-src 'self'; style-src 'self'; img-src 'self' data:; connect-src 'self' https: http:; frame-src 'none'; form-action 'none'; base-uri 'none'",
     "icons": {
         "16": "icons/icon16.png",

src/background/index.js

@@ -17,7 +17,11 @@ const { applyChainSwitchFields } = require("../shared/chainSwitchFields");
 // the same prohibition reported early, not the guarantee.
 const { getState, updateState } = require("./state");
 const { StateUnusableError } = require("../shared/stateSchema");
-const { refreshBalances, getProvider } = require("../shared/balances");
+const {
+    refreshBalances,
+    dropUntrackedTokens,
+    getProvider,
+} = require("../shared/balances");
 const { debugFetch, log } = require("../shared/log");
 const {
     verifySignedTx,
@@ -379,14 +383,26 @@ async function proxyRpc(method, params) {
     return json.result;
 }
 
-// The site-connection approval the toolbar popup is set to open, or null while
-// it opens the wallet. Set only by resetPopupUrl() and showInToolbarPopup().
+// The approval the toolbar popup is set to open, or null while it opens the
+// wallet. Set only by updateToolbarPopup() and showInToolbarPopup().
 let toolbarPopupApprovalId = null;
 
-function resetPopupUrl() {
-    toolbarPopupApprovalId = null;
+// Point the toolbar popup at the oldest pending approval whose window closed,
+// or at the wallet when there is none. The user can then answer that approval
+// from the toolbar popup. pendingApprovals lists approvals in the order they
+// were added, so the first one found is the oldest. An approval held by a
+// running attempt is skipped until that attempt ends.
+function updateToolbarPopup() {
+    const closed = Object.values(pendingApprovals).find(
+        (approval) => approval.windowClosed && !approval.attemptInFlight,
+    );
+    toolbarPopupApprovalId = closed ? closed.id : null;
     if (actionNs && typeof actionNs.setPopup === "function") {
-        actionNs.setPopup({ popup: "src/popup/index.html" });
+        actionNs.setPopup({
+            popup: closed
+                ? "src/popup/index.html?approval=" + closed.id
+                : "src/popup/index.html",
+        });
     }
 }
 
@@ -416,15 +432,16 @@ function settleApproval(id, result, options) {
     // approval stops being alive.
     releaseTxApprovalSlotFor(id);
     approval.resolve(result);
-    resetPopupUrl();
+    updateToolbarPopup();
     return true;
 }
 
 // What a pending approval resolves to when it is given up on rather than
-// answered: the window was closed, or could not be opened at all. A tx or sign
-// approval answers the requesting page in EIP-1193 shape; a site-connection or
-// network-switch approval answers its handler in the shape the popup's
-// decision has, as a refusal.
+// answered: a site-connection or network-switch window was closed, or the
+// window could not be opened at all. An address switch in the wallet gives up
+// pending approvals too. A tx or sign approval answers the requesting page in
+// EIP-1193 shape; a site-connection or network-switch approval answers its
+// handler in the shape the popup's decision has, as a refusal.
 function abandonedResult(approval, code, message) {
     if (approval.type === "tx" || approval.type === "sign") {
         return { error: { code, message } };
@@ -432,8 +449,9 @@ function abandonedResult(approval, code, message) {
     return { approved: false, remember: false };
 }
 
-// A window the user closed without answering is a refusal by the user, which
-// is 4001 and the wording every other rejection path already uses.
+// A site-connection or network-switch window the user closed without answering
+// is a refusal by the user, which is 4001 and the wording every other rejection
+// path already uses.
 const APPROVAL_REJECTED_CODE = 4001;
 const APPROVAL_REJECTED_MESSAGE = "User rejected the request.";
 
@@ -461,31 +479,16 @@ const APPROVAL_WINDOW_FAILED_MESSAGE =
 function claimApproval(approval) {
     if (approval.attemptInFlight) return false;
     approval.attemptInFlight = true;
+    updateToolbarPopup();
     return true;
 }
 
 // Release an approval whose attempt failed in a way the user can retry.
-// Nothing was broadcast, so the next attempt may claim it.
-//
-// Unless the window it would be retried in is already gone. The user closed it
-// while the attempt was running and settleApproval() declined then, correctly,
-// because the attempt still owned the approval; the attempt has now failed, so
-// nothing owns it and nothing can reach it. Left standing it would hold the
-// requesting page's promise open forever and, with it, the transaction
-// approval slot. It is settled here as the rejection the closed window
-// already meant.
+// Nothing was broadcast, so the next attempt may claim it. If the user closed
+// its window while the attempt ran, the toolbar popup opens it for that retry.
 function releaseApproval(approval) {
     approval.attemptInFlight = false;
-    if (approval.windowClosed) {
-        settleApproval(
-            approval.id,
-            abandonedResult(
-                approval,
-                APPROVAL_REJECTED_CODE,
-                APPROVAL_REJECTED_MESSAGE,
-            ),
-        );
-    }
+    updateToolbarPopup();
 }
 
 // Open approval in a separate popup window, unless it is no longer pending.
@@ -708,9 +711,7 @@ function isExtensionSender(sender) {
 // had refused.
 //
 // TX and sign approvals do not decide here. They stay pending across a
-// disconnect. When their window closes, the windows.onRemoved listener below
-// rejects them, unless an approved attempt is still running, in which case
-// that attempt answers the page.
+// disconnect, and across their window closing, until the user answers them.
 runtime.onConnect.addListener((port) => {
     if (port.name.startsWith("approval:")) {
         const id = port.name.split(":")[1];
@@ -738,9 +739,7 @@ runtime.onConnect.addListener((port) => {
             const approval = pendingApprovals[id];
             if (approval) {
                 if (approval.type === "tx" || approval.type === "sign") {
-                    // When its window closes, windows.onRemoved rejects it,
-                    // unless an approved attempt is still running, in which
-                    // case that attempt answers the page.
+                    // It stays pending until the user answers it.
                     return;
                 }
                 settleApproval(id, { approved: false, remember: false });
@@ -1293,7 +1292,7 @@ async function broadcastAccountsChanged() {
             windowsRemove(approval.windowId).catch(() => {});
         }
     }
-    resetPopupUrl();
+    updateToolbarPopup();
     // An address switch ends every connection allowed without "Remember". This
     // waits on storage, so it comes after the pending approvals above, which
     // are still rejected the moment the switch arrives.
@@ -1386,6 +1385,10 @@ const RECENT_BALANCE_REFRESH_MS = Math.floor(BALANCE_REFRESH_PERIOD_MS / 2);
 // back over them (https://git.eeqj.de/sneak/AutistMask/issues/577).
 // lastBalanceRefresh is left as the switch set it, so the next tick refreshes
 // the new network.
+//
+// Blockscout may have answered just before the user turned "Use Blockscout"
+// off. So the save reads the stored setting again, and drops every token the
+// user has not tracked if the setting is off.
 async function backgroundRefresh() {
     const s = await getState();
     const now = Date.now();
@@ -1423,6 +1426,9 @@ async function backgroundRefresh() {
                 }
             }
         }
+        if (!fresh.useBlockscout) {
+            dropUntrackedTokens(fresh.wallets, fresh.trackedTokens);
+        }
         fresh.lastBalanceRefresh = now;
     });
 }
@@ -1478,36 +1484,44 @@ if (runtime.onStartup) {
 }
 startBackgroundJobs();
 
-// When approval window is closed without a response, treat as rejection.
-// "Without a response" is the operative part: the popup stays open across the
-// verify and broadcast it is waiting on, so a user closing an apparently-hung
-// window is an ordinary event with an attempt already in flight behind it.
-// settleApproval() refuses those, which leaves the attempt to report its real
-// outcome to the page — and the window is recorded as gone, so that an attempt
-// which then fails retryably settles instead of waiting in a window that no
-// longer exists.
+// The toolbar popup keeps its URL when the worker stops. A worker that starts
+// holds no approvals, so the toolbar popup is pointed back at the wallet.
+updateToolbarPopup();
+
+// A transaction or signature approval stays pending when its window closes.
+// The browser can close that window when the user clicks away from it, for
+// example to copy the password from a password manager. The approval is marked
+// as closed, so the toolbar popup can open it (see updateToolbarPopup()). An
+// attempt already running when the window closes goes on and reports its
+// outcome to the page.
 //
-// A site-connection or network-switch approval whose popup connected its port
-// is not decided here. That popup approves and closes in the same breath, and
-// this event races the decision on a channel of its own — the same race the
-// port exists to end. Its port disconnect says the same thing this event does,
-// in an order that is defined, so the disconnect is left to say it. The window
-// closing before any port connected is the one case with nothing else to speak
-// for it, and is rejected here so the dApp is not left waiting on a window that
-// is gone.
+// This listener rejects a site-connection or network-switch approval whose
+// window closes before its popup connected its port. Once the port is
+// connected, the approval is left to the port. That popup approves and closes
+// in the same breath, and this event races the decision on a channel of its
+// own — the same race the port exists to end. Its port disconnect says the
+// same thing this event does, in an order that is defined, so the disconnect is
+// left to say it. The window closing before any port connected is the one case
+// with nothing else to speak for it, and is rejected here so the dApp is not
+// left waiting on a window that is gone.
 if (windowsNs && windowsNs.onRemoved) {
     windowsNs.onRemoved.addListener((windowId) => {
         for (const [id, approval] of Object.entries(pendingApprovals)) {
             if (approval.windowId !== windowId) continue;
-            const decidedOnPort =
-                approval.type !== "tx" && approval.type !== "sign";
-            if (decidedOnPort && approval.portConnected) continue;
-            const rejection = abandonedResult(
-                approval,
-                APPROVAL_REJECTED_CODE,
-                APPROVAL_REJECTED_MESSAGE,
+            if (approval.type === "tx" || approval.type === "sign") {
+                approval.windowClosed = true;
+                updateToolbarPopup();
+                continue;
+            }
+            if (approval.portConnected) continue;
+            settleApproval(
+                id,
+                abandonedResult(
+                    approval,
+                    APPROVAL_REJECTED_CODE,
+                    APPROVAL_REJECTED_MESSAGE,
+                ),
             );
-            if (!settleApproval(id, rejection)) approval.windowClosed = true;
         }
     });
 }
@@ -1652,7 +1666,9 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
                 });
                 return false;
             }
-            return true;
+            // The popup waits for this answer before it closes its window.
+            sendResponse(null);
+            return false;
         }
 
         // The popup signs; it reports back here when it could not. Keep the
@@ -1852,7 +1868,8 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
                 });
                 return false;
             }
-            return true;
+            sendResponse(null);
+            return false;
         }
 
         // The popup signs; it reports back here when it could not. Keep the

src/background/state.js

@@ -18,11 +18,10 @@
 //   updateState(fn)   read fresh, apply fn to that fresh record, write it
 //                     back — all holding the lock every write of the stored
 //                     record takes, so no other write lands in between, by
-//                     the background or by any page except a page in a
-//                     Firefox private window (README, "Stored state and its
-//                     version"). The read is one storage round trip ahead of
-//                     the write rather than a page lifetime ahead of it
-//                     (which is what made the popup's saveState() need a
+//                     the background or by any page (README, "Stored state
+//                     and its version"). The read is one storage round trip
+//                     ahead of the write rather than a page lifetime ahead of
+//                     it (which is what made the popup's saveState() need a
 //                     per-field merge against a baseline at all).
 //
 // A handler that must both read and write therefore does its network work
@@ -73,8 +72,7 @@ async function updateStateOnce(mutate) {
 // src/shared/browserApi.js) is held from the read to the write: two
 // background turns, or a turn and a page's save, never interleave
 // (https://git.eeqj.de/sneak/AutistMask/issues/641). Every page's save waits
-// while it is held, except a page in a Firefox private window, which Firefox
-// gives locks of its own (README, "Stored state and its version").
+// while it is held (README, "Stored state and its version").
 //
 // `mutate` must also not call updateState() itself, directly or through
 // anything it awaits: the inner turn waits for the lock the outer one holds,

src/popup/index.html

@@ -43,6 +43,38 @@
             <!-- ============ WELCOME / FIRST USE ============ -->
             <div id="view-welcome" class="view hidden">
                 <p class="mb-3">Welcome! To get started, add a wallet.</p>
+                <div class="bg-well p-3 mx-1 mb-3">
+                    <p class="text-xs mb-2">
+                        This wallet sends your data only to the Ethereum RPC
+                        endpoint, unless you turn on one of these. You can
+                        change them later in Settings.
+                    </p>
+                    <label
+                        class="text-xs flex items-center gap-1 cursor-pointer mb-1"
+                    >
+                        <input type="checkbox" id="welcome-use-blockscout" />
+                        Use Blockscout
+                    </label>
+                    <p class="text-xs text-muted mb-2">
+                        Shows transaction history, transaction details and the
+                        tokens you have not tracked. Sends your addresses, and
+                        the hash of each transaction you open, to the Blockscout
+                        API.
+                    </p>
+                    <label
+                        class="text-xs flex items-center gap-1 cursor-pointer mb-1"
+                    >
+                        <input
+                            type="checkbox"
+                            id="welcome-check-recipients-on-etherscan"
+                        />
+                        Check recipients on Etherscan
+                    </label>
+                    <p class="text-xs text-muted">
+                        Sends each recipient's address to Etherscan to check it
+                        for a phishing or scam label.
+                    </p>
+                </div>
                 <button
                     id="btn-welcome-add"
                     class="border border-border px-2 py-1 hover:bg-fg hover:text-bg cursor-pointer"
@@ -272,6 +304,10 @@
 
                 <!-- wallet list -->
                 <div id="wallet-list"></div>
+                <p id="home-tokens-note" class="text-xs text-muted py-1 hidden">
+                    Only tracked tokens are listed, because "Use Blockscout" is
+                    off in Settings.
+                </p>
 
                 <!-- recent transactions across all addresses -->
                 <div>
@@ -336,6 +372,13 @@
                     <div id="address-balances" class="min-h-[1.25rem]">
                         &nbsp;
                     </div>
+                    <p
+                        id="address-tokens-note"
+                        class="text-xs text-muted hidden"
+                    >
+                        Only tracked tokens are listed, because "Use Blockscout"
+                        is off in Settings.
+                    </p>
                 </div>
 
                 <!-- actions -->
@@ -526,12 +569,23 @@
                 </div>
                 <div class="mb-2">
                     <label class="block mb-1">What to send</label>
-                    <select
-                        id="send-token"
-                        class="border border-border p-1 w-full font-mono text-sm bg-bg text-fg"
-                    >
-                        <option value="ETH">ETH</option>
-                    </select>
+                    <!-- The token dropdown and the line under it. Both are
+                    hidden when AddressToken opens Send for its own token. -->
+                    <div id="send-token-dropdown">
+                        <select
+                            id="send-token"
+                            class="border border-border p-1 w-full font-mono text-sm bg-bg text-fg"
+                        >
+                            <option value="ETH">ETH</option>
+                        </select>
+                        <p
+                            id="send-tokens-note"
+                            class="text-xs text-muted hidden"
+                        >
+                            Only tracked tokens are listed, because "Use
+                            Blockscout" is off in Settings.
+                        </p>
+                    </div>
                     <div id="send-token-static" class="text-sm hidden"></div>
                 </div>
                 <div class="mb-2">
@@ -660,6 +714,13 @@
                         phishing/scam. Do not send funds to this address.
                     </div>
                 </div>
+                <p
+                    id="confirm-etherscan-note"
+                    class="mb-2 text-xs text-muted hidden"
+                >
+                    This address was not checked on Etherscan, because "Check
+                    recipients on Etherscan" is off in Settings.
+                </p>
                 <div
                     id="confirm-errors"
                     class="mb-2 border border-border border-dashed p-2 invisible min-h-[1.25rem]"
@@ -750,6 +811,7 @@
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">Amount</div>
                     <div id="wait-tx-summary" class="font-bold"></div>
+                    <div id="wait-tx-token-note"></div>
                 </div>
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">To</div>
@@ -796,6 +858,7 @@
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">Amount</div>
                     <div id="error-tx-summary" class="font-bold"></div>
+                    <div id="error-tx-token-note"></div>
                 </div>
                 <div class="mb-3">
                     <div class="text-xs text-muted mb-1">To</div>
@@ -917,6 +980,23 @@
                     </button>
                 </div>
 
+                <div class="bg-well p-3 mx-1 mb-3">
+                    <h3 class="font-bold mb-1">Passwords</h3>
+                    <label
+                        class="text-xs flex items-center gap-1 cursor-pointer mb-1"
+                    >
+                        <input
+                            type="checkbox"
+                            id="settings-allow-weak-passwords"
+                        />
+                        Allow weak passwords
+                    </label>
+                    <p class="text-xs text-muted">
+                        Lets you choose a password shorter than 12 characters
+                        when you add a wallet.
+                    </p>
+                </div>
+
                 <div class="bg-well p-3 mx-1 mb-3">
                     <h3 class="font-bold mb-1">Tracked Tokens</h3>
                     <p class="text-xs text-muted mb-2">
@@ -1002,9 +1082,21 @@
 
                 <div class="bg-well p-3 mx-1 mb-3">
                     <h3 class="font-bold mb-1">Blockscout API</h3>
+                    <label
+                        class="text-xs flex items-center gap-1 cursor-pointer mb-1"
+                    >
+                        <input type="checkbox" id="settings-use-blockscout" />
+                        Use Blockscout
+                    </label>
+                    <p class="text-xs text-muted mb-2">
+                        Shows transaction history, transaction details and the
+                        tokens you have not tracked. Sends your addresses, and
+                        the hash of each transaction you open, to the Blockscout
+                        API below.
+                    </p>
                     <p class="text-xs text-muted mb-1">
-                        Used to fetch token balances and transaction history.
-                        Change this if you run your own Blockscout instance.
+                        Change the URL below if you run your own Blockscout
+                        instance.
                     </p>
                     <input
                         type="text"
@@ -1019,6 +1111,23 @@
                     </button>
                 </div>
 
+                <div class="bg-well p-3 mx-1 mb-3">
+                    <h3 class="font-bold mb-1">Etherscan</h3>
+                    <label
+                        class="text-xs flex items-center gap-1 cursor-pointer mb-1"
+                    >
+                        <input
+                            type="checkbox"
+                            id="settings-check-recipients-on-etherscan"
+                        />
+                        Check recipients on Etherscan
+                    </label>
+                    <p class="text-xs text-muted">
+                        Sends each recipient's address to Etherscan to check it
+                        for a phishing or scam label.
+                    </p>
+                </div>
+
                 <div class="bg-well p-3 mx-1 mb-3">
                     <h3 class="font-bold mb-1">Token Spam Protection</h3>
                     <p class="text-xs text-muted mb-2">
@@ -1291,6 +1400,13 @@
                 >
                     &nbsp;
                 </div>
+                <p
+                    id="delete-address-tokens-note"
+                    class="text-xs text-muted mb-2 hidden"
+                >
+                    Only tracked tokens are listed, because "Use Blockscout" is
+                    off in Settings.
+                </p>
                 <p class="text-xs text-muted mb-3">
                     A wallet always keeps at least one address. To remove the
                     last one, delete the whole wallet from Settings instead.
@@ -1504,6 +1620,16 @@
                     </div>
                 </div>
 
+                <!-- Shown in place of the block, decoded details, network
+                details and raw data, which only Blockscout gives. -->
+                <p
+                    id="tx-detail-blockscout-note"
+                    class="text-xs text-muted mx-1 mb-3 hidden"
+                >
+                    This screen shows no block, decoded details, network details
+                    or raw data, because "Use Blockscout" is off in Settings.
+                </p>
+
                 <!-- ── Decoded details ── -->
                 <div id="tx-detail-calldata-section" class="hidden">
                     <div class="bg-well p-3 mx-1 mb-3">

src/popup/index.js

@@ -5,12 +5,14 @@ const {
     state,
     saveState,
     onSaveFailure,
+    takeStoredNetwork,
     loadState,
 } = require("../shared/state");
 const { StateUnusableError } = require("../shared/stateSchema");
 const { log, setRuntimeDebug } = require("../shared/log");
 const { refreshPrices } = require("../shared/prices");
-const { refreshBalances } = require("../shared/balances");
+const { refreshBalances, dropUntrackedTokens } = require("../shared/balances");
+const { clearPopupCaches } = require("../shared/chainSwitch");
 const {
     $,
     showView,
@@ -22,6 +24,7 @@ const {
 } = require("./views/helpers");
 const { applyTheme } = require("./theme");
 const {
+    onStorageChanged,
     tabsGetCurrent,
     tabsGetZoom,
     windowsGetCurrent,
@@ -68,20 +71,28 @@ let refreshInFlight = false;
 // the recovery screen: there is no profile left to refresh.
 let refreshTimer = null;
 
+// The refresh first takes the stored network, "Use Blockscout" and "Check
+// recipients on Etherscan" (followStoredSettings() below). So the screens it
+// draws reflect any change saved elsewhere.
+//
 // The refresh writes into a copy of the wallets. Inside the save, under the
 // lock, its results are copied onto the address records in `state` only if the
 // network it ran on is still the active one, on this page and in the stored
 // record; the background's switch, after the user approves a site's request,
-// changes only the stored record. A switch while the refresh ran cleared every
-// address's balances (applyChainSwitchFields() in
-// src/shared/chainSwitchFields.js), and the previous network's must not come
-// back over them (https://git.eeqj.de/sneak/AutistMask/issues/577). A dropped
-// refresh is not recorded as done. Results are copied by address, so an address
-// added or removed meanwhile is left as it is.
+// reaches this page only after the stored record (followStoredSettings()).
+// A switch while the refresh ran cleared every address's balances
+// (applyChainSwitchFields() in src/shared/chainSwitchFields.js), and the
+// previous network's must not come back over them
+// (https://git.eeqj.de/sneak/AutistMask/issues/577). A dropped refresh is not
+// recorded as done. Results are copied by address, so an address added or
+// removed meanwhile is left as it is. Blockscout may have answered before the
+// 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;
     refreshInFlight = true;
     try {
+        await followStoredSettings();
         const networkId = state.networkId;
         const wallets = structuredClone(state.wallets);
         await Promise.all([
@@ -113,6 +124,9 @@ async function doRefreshAndRender() {
                     }
                 }
             }
+            if (!stored.useBlockscout) {
+                dropUntrackedTokens(state.wallets, stored.trackedTokens);
+            }
             state.lastBalanceRefresh = Date.now();
             return true;
         });
@@ -147,6 +161,7 @@ const ctx = {
     renderWalletList,
     doRefreshAndRender,
     startRefresh,
+    restoreView,
     pageClosed: pageClosed.signal,
     showAddWalletView: () => {
         pushCurrentView();
@@ -214,6 +229,47 @@ function fallbackView() {
     showView("main");
 }
 
+// When the background saves a network switch, once the user approves a site's
+// request, or another popup page saves one, this page follows the stored
+// record. It takes the network the record names as a save reads it, holding
+// the lock, so no later save of this page writes the previous network back, and
+// then leaves the page as a switch in Settings leaves it. This page's own
+// switch in Settings is made under the lock as well (onChainSwitch() in
+// src/shared/chainSwitch.js), so a record naming a network other than this
+// page's always holds a switch saved elsewhere, and a switch the user picks
+// here while this waits for the lock is made after it.
+//
+// Another page may change "Use Blockscout" or "Check recipients on Etherscan".
+// This page takes either change the same way and draws its screens again. This
+// page's own changes to the two settings are made under the lock too
+// (views/settings.js, views/welcome.js).
+async function followStoredSettings() {
+    let changed = false;
+    // A failed save is reported by saveState() itself: see onSaveFailure().
+    await saveState((stored) => {
+        if (stored.networkId !== state.networkId) {
+            settings.cutViewStack();
+            takeStoredNetwork(stored);
+            clearPopupCaches();
+            changed = true;
+        }
+        if (stored.useBlockscout !== state.useBlockscout) {
+            settings.setUseBlockscout(stored.useBlockscout);
+            changed = true;
+        }
+        if (
+            stored.checkRecipientsOnEtherscan !==
+            state.checkRecipientsOnEtherscan
+        ) {
+            state.checkRecipientsOnEtherscan =
+                stored.checkRecipientsOnEtherscan;
+            changed = true;
+        }
+        if (!changed) return false;
+    }).catch(() => {});
+    if (changed) settings.showNewSettings();
+}
+
 // The background opens the approval window as wide as the page, but the
 // browser counts the window's frame in that width, and a screen taller than
 // the window takes a vertical scrollbar out of it too. So once the screen is
@@ -225,9 +281,9 @@ function fallbackView() {
 // zoom it reports, 170% among them, so once the page has its new width (its
 // resize event) it is measured again, and the window widened again while the
 // page still falls short, three times at most. A window that cannot grow sends
-// no resize event, and the page stops there. The connection prompt can also
-// show in the toolbar popup, whose window is the user's browser window; that
-// one is left alone.
+// no resize event, and the page stops there. An approval can also show in the
+// toolbar popup, whose window is the user's browser window; that one is left
+// alone.
 async function widenApprovalWindow() {
     const page = document.documentElement;
     if (page.scrollWidth <= page.clientWidth) return;
@@ -358,8 +414,27 @@ async function init() {
     settingsAddToken.init(ctx);
     deleteAddress.init(ctx);
 
+    // This page follows a record only when its network, "Use Blockscout" or
+    // "Check recipients on Etherscan" differs from this page's. A record
+    // written by this page's own save matches this page. A record naming no
+    // network is no switch.
+    onStorageChanged((changes) => {
+        const written = changes.autistmask && changes.autistmask.newValue;
+        if (!written || !written.networkId) return;
+        if (
+            written.networkId !== state.networkId ||
+            written.useBlockscout !== state.useBlockscout ||
+            written.checkRecipientsOnEtherscan !==
+                state.checkRecipientsOnEtherscan
+        ) {
+            followStoredSettings();
+        }
+    });
+    // A change saved since loadState() above, before there was a listener.
+    followStoredSettings();
+
     if (!state.hasWallet) {
-        showView("welcome");
+        welcome.show();
     } else {
         renderWalletList();
         restoreView();

src/popup/viewRouter.js

@@ -38,11 +38,16 @@ function markViewRendered(view) {
     if (view) renderedViews.add(view);
 }
 
-// Begin a fresh page-load scope. The popup gets one by being loaded, and
-// asks for one when the user switches the network, because every screen
-// then on the page shows the previous network (views/settings.js); the
-// unit tests, which simulate several page loads against one module
-// instance, ask for one too.
+// Begin a fresh page-load scope. The popup gets one by being loaded. It also
+// asks for one when every screen on the page is out of date:
+//
+//   - after a network switch, since those screens show the previous network
+//     (showNewSettings() in views/settings.js)
+//   - after "Use Blockscout" or "Check recipients on Etherscan" changes, here
+//     or on another page, since those screens were drawn under the old setting
+//
+// The unit tests ask for one too. They simulate several page loads against one
+// module instance.
 function resetRenderedViews() {
     renderedViews.clear();
 }

src/popup/views/addWallet.js

@@ -132,7 +132,8 @@ function validatePassword() {
         showError("add-wallet-password-error", "Please choose a password.");
         return null;
     }
-    if (pw.length < 12) {
+    // "Allow weak passwords" in Settings lifts the 12-character minimum.
+    if (!state.allowWeakPasswords && pw.length < 12) {
         showError(
             "add-wallet-password-error",
             "Password must be at least 12 characters.",

src/popup/views/addressDetail.js

@@ -4,6 +4,7 @@ const {
     showFlash,
     balanceLinesForAddress,
     txCounterpartyHtml,
+    HISTORY_OFF_TEXT,
     addressTitle,
     escapeHtml,
     displaySymbol,
@@ -83,6 +84,8 @@ function show() {
                 ctx.showAddressToken();
             });
         });
+    // Only Blockscout reports the tokens the user has not tracked.
+    $("address-tokens-note").classList.toggle("hidden", !!state.useBlockscout);
     renderSendTokenSelect(addr);
     $("tx-list").innerHTML =
         '<div class="text-muted text-xs py-1">Loading...</div>';
@@ -155,6 +158,10 @@ async function loadTransactions(address) {
 
 function renderTransactions(txs) {
     const list = $("tx-list");
+    if (!state.useBlockscout) {
+        list.innerHTML = `<div class="text-muted text-xs py-1">${escapeHtml(HISTORY_OFF_TEXT)}</div>`;
+        return;
+    }
     if (txs.length === 0) {
         list.innerHTML =
             '<div class="text-muted text-xs py-1">No transactions found.</div>';
@@ -229,7 +236,7 @@ function init(_ctx) {
         }
         $("send-to").value = "";
         $("send-amount").value = "";
-        $("send-token").classList.remove("hidden");
+        $("send-token-dropdown").classList.remove("hidden");
         $("send-token-static").classList.add("hidden");
         updateSendBalance();
         resetSendValidation();

src/popup/views/addressToken.js

@@ -7,6 +7,7 @@ const {
     showFlash,
     flashCopyFeedback,
     txCounterpartyHtml,
+    HISTORY_OFF_TEXT,
     addressTitle,
     escapeHtml,
     displaySymbol,
@@ -239,6 +240,10 @@ async function loadTransactions(address, tokenId) {
 
 function renderTransactions(txs) {
     const list = $("address-token-tx-list");
+    if (!state.useBlockscout) {
+        list.innerHTML = `<div class="text-muted text-xs py-1">${escapeHtml(HISTORY_OFF_TEXT)}</div>`;
+        return;
+    }
     if (txs.length === 0) {
         list.innerHTML =
             '<div class="text-muted text-xs py-1">No transactions found.</div>';
@@ -324,7 +329,7 @@ function init(_ctx) {
             $("send-token").value = tokenId;
         }
         // Hide dropdown, show static token display
-        $("send-token").classList.add("hidden");
+        $("send-token-dropdown").classList.add("hidden");
         let staticHtml = `<div class="font-bold">${escapeHtml(displaySymbol(currentSymbol))}</div>`;
         if (tokenId !== "ETH") {
             staticHtml += `<div class="text-xs">${renderAddressHtml(tokenId)}</div>`;

src/popup/views/approval.js

@@ -11,6 +11,7 @@ const {
     onViewLeave,
     formatFee,
     tokenLabel,
+    blockscoutOffTokenNoteHtml,
     tokenSourcesByChainId,
 } = require("./helpers");
 const { state, saveState, currentNetwork } = require("../../shared/state");
@@ -54,7 +55,7 @@ const {
 } = require("../../shared/approvalVerify");
 const txStatus = require("./txStatus");
 const uniswap = require("../../shared/uniswap");
-const { notify, runtimeApi, sendMessage } = require("../../shared/browserApi");
+const { runtimeApi, sendMessage } = require("../../shared/browserApi");
 
 const erc20Iface = new Interface(ERC20_ABI);
 
@@ -401,6 +402,10 @@ function showTxApproval(details) {
             if (d.address) {
                 if (d.isToken) {
                     detailsHtml += `<div class="font-bold">${escapeHtml(tokenLabel(d.address, approvedTx.chainId) || "Unknown token")}</div>`;
+                    detailsHtml += blockscoutOffTokenNoteHtml(
+                        d.address,
+                        approvedTx.chainId,
+                    );
                 }
                 detailsHtml += approvalAddressHtml(
                     d.address,
@@ -623,10 +628,7 @@ function permitWarningHtml(types, primaryType, domain, message) {
             return "";
     }
 
-    const sources = {
-        trackedTokens: state.trackedTokens,
-        wallets: state.wallets,
-    };
+    const sources = tokenSourcesByChainId();
     const spender = addressOrNull(
         declaredField(types, primaryType, message, "spender")?.value,
     );
@@ -655,6 +657,7 @@ function permitWarningHtml(types, primaryType, domain, message) {
         html += `<div class="mb-2"><div>Token</div>`;
         if (token) {
             html += `<div>${escapeHtml(tokenLabel(token) || "Unknown token")}</div>`;
+            html += blockscoutOffTokenNoteHtml(token);
             html += approvalAddressHtml(token);
         } else {
             html += `<div>Unknown</div>`;
@@ -1139,12 +1142,21 @@ function init(_ctx) {
         }
     });
 
-    $("btn-reject-tx").addEventListener("click", () => {
-        notify({
+    // The window closes only once the background has the rejection. A message
+    // sent as the window closes can be lost, and a closed window does not
+    // reject the request. After Confirm, the background refuses a rejection
+    // while the transaction is being sent. The window then stays open and
+    // shows the background's message.
+    $("btn-reject-tx").addEventListener("click", async () => {
+        const response = await sendMessage({
             type: "AUTISTMASK_TX_RESPONSE",
             id: approvalId,
             approved: false,
-        });
+        }).catch(() => null);
+        if (response && response.error) {
+            showError("approve-tx-error", response.error);
+            return;
+        }
         window.close();
     });
 
@@ -1267,12 +1279,18 @@ function init(_ctx) {
         if (outcome.retryable) setSignButtonBusy(false);
     });
 
-    $("btn-reject-sign").addEventListener("click", () => {
-        notify({
+    // As for the transaction's Reject above. After Sign, the background
+    // refuses a rejection while the signature is being checked.
+    $("btn-reject-sign").addEventListener("click", async () => {
+        const response = await sendMessage({
             type: "AUTISTMASK_SIGN_RESPONSE",
             id: approvalId,
             approved: false,
-        });
+        }).catch(() => null);
+        if (response && response.error) {
+            showError("approve-sign-error", response.error);
+            return;
+        }
         window.close();
     });
 }

src/popup/views/confirmTx.js

@@ -334,6 +334,11 @@ function show(txInfo) {
     $("confirm-contract-warning").style.visibility = "hidden";
     $("confirm-burn-warning").style.visibility = "hidden";
     $("confirm-etherscan-warning").style.visibility = "hidden";
+    // While "Check recipients on Etherscan" is off, there is no Etherscan
+    // warning to reserve space for. A line in its place says the check is off.
+    const etherscanOn = !!state.checkRecipientsOnEtherscan;
+    $("confirm-etherscan-warning").classList.toggle("hidden", !etherscanOn);
+    $("confirm-etherscan-note").classList.toggle("hidden", etherscanOn);
 
     // Show burn warning via reserved element (in addition to inline warning)
     if (isBurnAddress(txInfo.to)) {

src/popup/views/deleteAddress.js

@@ -119,6 +119,11 @@ function show(walletIdx, addrIdx) {
 
     $("delete-address-recovery").textContent = recoveryPathText(wallet);
     $("delete-address-balance").innerHTML = balanceWarningHtml(addr);
+    // Only Blockscout reports the tokens the user has not tracked.
+    $("delete-address-tokens-note").classList.toggle(
+        "hidden",
+        !!state.useBlockscout,
+    );
 
     setFlash("");
     showView("delete-address-confirm");

src/popup/views/deleteWallet.js

@@ -16,6 +16,7 @@ const {
     broadcastActiveChanged,
 } = require("../../shared/walletDelete");
 const { INVISIBLE_CHARACTERS } = require("../../shared/symbolSpoof");
+const welcome = require("./welcome");
 
 let deleteWalletIndex = null;
 let lostPasswordIndex = null;
@@ -135,7 +136,7 @@ async function finishDelete(walletIdx) {
         // Save before broadcasting: the background reads the active
         // address back out of storage to build accountsChanged.
         if (activeAddressChanged) broadcastActiveChanged();
-        showView("welcome");
+        welcome.show();
         return;
     }
 

src/popup/views/helpers.js

@@ -21,7 +21,10 @@ const {
     truncateAmountNeverZero,
     isBelowOneMillionth,
 } = require("../../shared/amountDisplay");
-const { resolveTokenSymbol } = require("../../shared/approvalAmount");
+const {
+    resolveTokenDecimals,
+    resolveTokenSymbol,
+} = require("../../shared/approvalAmount");
 const { getProvider } = require("../../shared/balances");
 const { DEBUG } = require("../../shared/constants");
 const { escapeHtml } = require("../../shared/html");
@@ -306,10 +309,16 @@ function nativeCurrency() {
 // names a token on one network only, and every token balance held is the
 // active network's, so another network gets the tokens tracked on it
 // (state.networkTrackedTokens, see applyChainSwitchFields()) and no balances.
+//
+// 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();
     if (net && net.id === state.networkId) {
-        return { trackedTokens: state.trackedTokens, wallets: state.wallets };
+        return {
+            trackedTokens: state.trackedTokens,
+            wallets: state.useBlockscout ? state.wallets : [],
+        };
     }
     return {
         trackedTokens: (net && state.networkTrackedTokens[net.id]) || [],
@@ -317,11 +326,39 @@ function tokenSourcesByChainId(chainId) {
     };
 }
 
-// The symbol shown for a token line on the network with `chainId`, or on the
-// active network when none is given: from the bundled list, the tokens the
-// user tracks, and the explorer's report, the sources the amount line's scale
-// comes from. Null when no source names one, so the token lines keep saying
-// `Unknown token` for a token nothing knows.
+// The line shown under a token while "Use Blockscout" is off. The token gets
+// the line only when the bundled list and the tracked tokens lack its name or
+// decimals. Otherwise this returns "". The token is a contract address on the
+// network with `chainId`, or on the active network when none is given. "ETH"
+// and null are no contract, and get "". A token that is not text also gets "":
+// WaitTx and ErrorTx pass a token restored from storage unchecked.
+function blockscoutOffTokenNoteHtml(token, chainId) {
+    if (typeof token !== "string") return "";
+    if (state.useBlockscout || !token || token === "ETH") return "";
+    const sources = tokenSourcesByChainId(chainId);
+    if (
+        resolveTokenSymbol(token, sources) !== null &&
+        resolveTokenDecimals(token, sources) !== null
+    ) {
+        return "";
+    }
+    return (
+        '<div class="text-xs text-muted">Blockscout\'s report of your balances' +
+        ' is not used to name this token, because "Use Blockscout" is off in' +
+        " Settings.</div>"
+    );
+}
+
+// The symbol shown for a token line, from these sources in order:
+//
+// - the bundled list
+// - the tokens the user tracks
+// - the explorer's report, while "Use Blockscout" is on
+//
+// The network is the one with `chainId`, or the active network when none is
+// given. The amount line's scale comes from the same sources. Null when no
+// source names one, so the token lines keep saying `Unknown token` for a token
+// nothing knows.
 function tokenLabel(address, chainId) {
     return resolveTokenSymbol(address, tokenSourcesByChainId(chainId));
 }
@@ -534,6 +571,12 @@ function addressTitle(address, wallets) {
 const CONTRACT_CREATION_TEXT =
     "This transaction creates a new contract. It has no recipient.";
 
+// The line shown in place of the transaction history on Home, AddressDetail and
+// AddressToken while "Use Blockscout" is off. That history comes from
+// Blockscout alone.
+const HISTORY_OFF_TEXT =
+    'No transaction history is shown, because "Use Blockscout" is off in Settings.';
+
 // The last two lines of a transaction history row: the counterparty's colour
 // dot and name beside the amount, then its full address. A contract creation
 // the user sent has no counterparty (its `to` is ""), so its row has the
@@ -791,6 +834,7 @@ module.exports = {
     unknownableAmount,
     nativeCurrency,
     tokenSourcesByChainId,
+    blockscoutOffTokenNoteHtml,
     tokenLabel,
     formatFee,
     addressDotHtml,
@@ -799,6 +843,7 @@ module.exports = {
     displaySymbol,
     addressTitle,
     CONTRACT_CREATION_TEXT,
+    HISTORY_OFF_TEXT,
     txCounterpartyHtml,
     formatAddressHtml,
     renderAddressHtml,

src/popup/views/home.js

@@ -7,6 +7,7 @@ const {
     timeAgo,
     addressDotHtml,
     txCounterpartyHtml,
+    HISTORY_OFF_TEXT,
     addressTitle,
     escapeHtml,
     displaySymbol,
@@ -100,6 +101,10 @@ let homeTxs = [];
 function renderHomeTxList(ctx) {
     const list = $("home-tx-list");
     if (!list) return;
+    if (!state.useBlockscout) {
+        list.innerHTML = `<div class="text-muted text-xs py-1">${escapeHtml(HISTORY_OFF_TEXT)}</div>`;
+        return;
+    }
     if (homeTxs.length === 0) {
         list.innerHTML =
             '<div class="text-muted text-xs py-1">No transactions found.</div>';
@@ -300,6 +305,8 @@ function walletListHtml() {
 
 function render(ctx) {
     const container = $("wallet-list");
+    // Only Blockscout reports the tokens the user has not tracked.
+    $("home-tokens-note").classList.toggle("hidden", !!state.useBlockscout);
     if (state.wallets.length === 0) {
         container.innerHTML =
             '<p class="text-muted py-2">No wallets yet. Add one to get started.</p>';
@@ -447,7 +454,7 @@ function init(ctx) {
         }
         $("send-to").value = "";
         $("send-amount").value = "";
-        $("send-token").classList.remove("hidden");
+        $("send-token-dropdown").classList.remove("hidden");
         $("send-token-static").classList.add("hidden");
         renderSendTokenSelect(addr);
         updateSendBalance();

src/popup/views/send.js

@@ -10,6 +10,7 @@ const {
     renderAddressHtml,
     attachCopyHandlers,
     goBack,
+    tokenSourcesByChainId,
 } = require("./helpers");
 const { state, currentAddress } = require("../../shared/state");
 let ctx;
@@ -141,6 +142,8 @@ function updateToValidation() {
 }
 
 function renderSendTokenSelect(addr) {
+    // Only Blockscout reports the tokens the user has not tracked.
+    $("send-tokens-note").classList.toggle("hidden", !!state.useBlockscout);
     const sel = $("send-token");
     sel.innerHTML = `<option value="ETH">${escapeHtml(nativeCurrency())}</option>`;
     const fraudSet = new Set(
@@ -185,7 +188,9 @@ function renderSendTokenSelect(addr) {
 // so the transfer is encoded with the number the user read rather than with
 // whatever the contract answers at signing time (see
 // src/shared/transferAmount.js). balances.js is formatting one explorer row at
-// fetch time and cannot consult a state it is in the middle of replacing.
+// fetch time and cannot consult a state it is in the middle of replacing. As on
+// the approval screens, tokenSourcesByChainId() gives the wallets only while
+// "Use Blockscout" is on.
 //
 // The two resolutions can therefore differ, and where they do, the stored
 // `balance` is a quantity computed at a scale this screen has just declined to
@@ -198,10 +203,7 @@ function tokenBalanceAndDecimals(addr, token) {
     const tb = (addr.tokenBalances || []).find(
         (t) => t.address.toLowerCase() === token.toLowerCase(),
     );
-    const tokenDecimals = resolveTokenDecimals(token, {
-        trackedTokens: state.trackedTokens,
-        wallets: state.wallets,
-    });
+    const tokenDecimals = resolveTokenDecimals(token, tokenSourcesByChainId());
     if (!tb) return { tokenBalance: "0", tokenDecimals };
     if (tokenDecimals === null) return { tokenBalance: null, tokenDecimals };
     return { tokenBalance: tb.balance ?? null, tokenDecimals };
@@ -401,8 +403,11 @@ function init(_ctx) {
             try {
                 const provider = getProvider(state.rpcUrl, state.networkId);
                 const resolved = await provider.resolveName(to);
+                // getProvider() does not look up a name resolved off-chain,
+                // so such a name comes back with no address too. The message
+                // covers both, in the one line the flash area shows.
                 if (!resolved) {
-                    showFlash("That ENS name has no address.");
+                    showFlash("That ENS name has no on-chain address.");
                     return;
                 }
                 resolvedTo = resolved;
@@ -426,7 +431,7 @@ function init(_ctx) {
     });
 
     $("btn-send-back").addEventListener("click", () => {
-        $("send-token").classList.remove("hidden");
+        $("send-token-dropdown").classList.remove("hidden");
         $("send-token-static").classList.add("hidden");
         goBack();
     });

src/popup/views/settings.js

@@ -17,6 +17,7 @@ const {
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const { onChainSwitch } = require("../../shared/chainSwitch");
 const { restorableStack } = require("../../shared/persistedState");
+const { dropUntrackedTokens } = require("../../shared/balances");
 const { resetRenderedViews, markViewRendered } = require("../viewRouter");
 const {
     log,
@@ -38,6 +39,8 @@ const {
 
 const { notify, sendMessage } = require("../../shared/browserApi");
 
+let ctx;
+
 let versionClickCount = 0;
 let versionClickTimer = null;
 
@@ -199,6 +202,10 @@ function show() {
     $("settings-rpc").value = state.rpcUrl;
     $("settings-blockscout").value = state.blockscoutUrl;
     $("settings-network").value = state.networkId;
+    // Set on every show, not only at init: Welcome can change these two.
+    $("settings-use-blockscout").checked = state.useBlockscout;
+    $("settings-check-recipients-on-etherscan").checked =
+        state.checkRecipientsOnEtherscan;
     renderTrackedTokens();
     renderSiteLists();
     renderWalletListSettings();
@@ -243,7 +250,77 @@ async function renderSiteLists() {
     );
 }
 
-function init(ctx) {
+// A network switch, made by the user here or saved by the background once the
+// user approved a site's request (src/popup/index.js), leaves every screen on
+// the page showing the previous network. Two functions leave the page as
+// README's Screen Map describes:
+//
+// - cutViewStack(), before the switch is saved, so that save keeps the cut for
+//   a popup closed straight after
+// - showNewSettings(), once `state` holds the new network
+//
+// The stack is cut at the first screen that cannot be rendered from saved
+// state, such as Send or AddToken, and at AddressToken unless it shows the
+// native token: any other token there was picked on the previous network, so
+// it is no longer selected either. Without a wallet the stack starts at
+// Welcome, which that cut would drop, and Welcome shows nothing from a network.
+// A change to "Use Blockscout" cuts the stack the same way (setUseBlockscout()
+// below).
+function cutViewStack() {
+    if (!state.hasWallet) return;
+    if (state.selectedToken !== "ETH") {
+        const tokenView = state.viewStack.indexOf("address-token");
+        if (tokenView !== -1) {
+            state.viewStack = state.viewStack.slice(0, tokenView);
+        }
+        state.selectedToken = null;
+    }
+    state.viewStack = restorableStack(state.viewStack, state.currentView);
+}
+
+// Sets "Use Blockscout" to `on` on this page. It is called inside a save,
+// holding the lock, for the user's change here or another page's
+// (followStoredSettings() in src/popup/index.js).
+//
+// Send's token dropdown was filled under the old setting, and Back cannot draw
+// Send again. So the stack is cut, as for a network switch. Turning the setting
+// off also drops every token the user has not tracked.
+function setUseBlockscout(on) {
+    state.useBlockscout = on;
+    cutViewStack();
+    if (!on) dropUntrackedTokens(state.wallets, state.trackedTokens);
+}
+
+// Draws the page again after a network switch, or after another page changed
+// "Use Blockscout" or "Check recipients on Etherscan". Every screen counts as
+// not yet rendered, so "Back" renders again any screen that a reopened popup
+// can render. Settings on top is brought up to date in place. Any other screen
+// is drawn again as a reopened popup draws it, which is Home for one that
+// cannot be rendered from saved state. Without a wallet any other screen is
+// Welcome or AddWallet. Back only unhides Welcome, so its two checkboxes are
+// set here.
+function showNewSettings() {
+    resetRenderedViews();
+    $("welcome-use-blockscout").checked = state.useBlockscout;
+    $("welcome-check-recipients-on-etherscan").checked =
+        state.checkRecipientsOnEtherscan;
+    if (state.currentView === "settings") {
+        markViewRendered("settings");
+        $("settings-network").value = state.networkId;
+        $("settings-rpc").value = state.rpcUrl;
+        $("settings-blockscout").value = state.blockscoutUrl;
+        $("settings-use-blockscout").checked = state.useBlockscout;
+        $("settings-check-recipients-on-etherscan").checked =
+            state.checkRecipientsOnEtherscan;
+        renderTrackedTokens();
+    } else if (state.hasWallet) {
+        ctx.restoreView();
+    }
+    updateDebugBanner(state.currentView);
+}
+
+function init(_ctx) {
+    ctx = _ctx;
     deleteWallet.init(ctx);
     showPhrase.init();
 
@@ -317,39 +394,49 @@ function init(ctx) {
         showFlash("Saved.");
     });
 
+    // Each change is made inside the save, holding the lock. So
+    // followStoredSettings() in src/popup/index.js never mistakes this page's
+    // unsaved change for one that another page saved.
+    //
+    // The screens under Settings were drawn under the old setting. So each
+    // change makes every screen but Settings count as not yet drawn, as a
+    // network switch does. Back then draws again any screen that a reopened
+    // popup can draw. Back only unhides Welcome, so its boxes are set here too.
+    $("settings-use-blockscout").addEventListener("change", async () => {
+        const on = $("settings-use-blockscout").checked;
+        await saveState(() => setUseBlockscout(on));
+        $("welcome-use-blockscout").checked = on;
+        resetRenderedViews();
+        markViewRendered("settings");
+    });
+
+    $("settings-check-recipients-on-etherscan").addEventListener(
+        "change",
+        async () => {
+            const on = $("settings-check-recipients-on-etherscan").checked;
+            await saveState(() => {
+                state.checkRecipientsOnEtherscan = on;
+            });
+            $("welcome-check-recipients-on-etherscan").checked = on;
+            resetRenderedViews();
+            markViewRendered("settings");
+        },
+    );
+
     const networkSelect = $("settings-network");
     networkSelect.addEventListener("change", async () => {
+        // Whether `state` already has the network picked is asked only once
+        // the switch holds the lock: while an earlier pick waits for it,
+        // `state` still has the network before that pick, and a pick back to
+        // that network must still be made.
         const newId = networkSelect.value;
-        if (newId === state.networkId) return;
-        // The screens beneath Settings show the previous network, so Back
-        // finds them as it does in a reopened popup: each is rendered again
-        // when Back lands on it, and the stack is cut at the first one that
-        // cannot be rendered from saved state, such as Send or AddToken. It
-        // is cut at AddressToken too, unless that shows the native token: any
-        // other token there was picked on the previous network. Without a
-        // wallet the stack starts at Welcome, which that cut would drop, and
-        // Welcome shows nothing from a network. The cut comes before the
-        // switch so that the switch's save keeps it for a popup closed
-        // straight after.
-        if (state.hasWallet) {
-            const tokenView = state.viewStack.indexOf("address-token");
-            if (tokenView !== -1 && state.selectedToken !== "ETH") {
-                state.viewStack = state.viewStack.slice(0, tokenView);
-            }
-            state.viewStack = restorableStack(state.viewStack, "settings");
-        }
+        cutViewStack();
         const net = await onChainSwitch(newId);
+        if (!net) return;
         // Open pages are told by the background, as after a site's approved
         // switch request.
         notify({ type: "AUTISTMASK_NETWORK_CHANGED", chainId: net.chainId });
-        resetRenderedViews();
-        // Settings itself, and the testnet banner above it, are brought up
-        // to date for the new network here.
-        markViewRendered("settings");
-        $("settings-rpc").value = state.rpcUrl;
-        $("settings-blockscout").value = state.blockscoutUrl;
-        renderTrackedTokens();
-        updateDebugBanner(state.currentView);
+        showNewSettings();
         showFlash("Switched to " + net.name + ".");
     });
 
@@ -412,6 +499,12 @@ function init(ctx) {
         await saveState();
     });
 
+    $("settings-allow-weak-passwords").checked = state.allowWeakPasswords;
+    $("settings-allow-weak-passwords").addEventListener("change", async () => {
+        state.allowWeakPasswords = $("settings-allow-weak-passwords").checked;
+        await saveState();
+    });
+
     $("btn-main-add-wallet").addEventListener("click", ctx.showAddWalletView);
 
     $("btn-settings-add-token").addEventListener(
@@ -484,4 +577,11 @@ function init(ctx) {
     });
 }
 
-module.exports = { init, show, renderSiteLists };
+module.exports = {
+    init,
+    show,
+    renderSiteLists,
+    cutViewStack,
+    setUseBlockscout,
+    showNewSettings,
+};

src/popup/views/stateRecovery.js

@@ -143,8 +143,6 @@ async function resetProfile() {
     try {
         // Under the lock every write of the stored record takes, so the erase
         // cannot land between another write's read and its write and be undone.
-        // A page in a Firefox private window is the exception: Firefox gives
-        // it locks of its own (README, "Stored state and its version").
         await withLock("autistmask", () => storageRemove("autistmask"));
     } catch (e) {
         log.errorf("state recovery: reset failed:", e);

src/popup/views/transactionDetail.js

@@ -26,6 +26,7 @@ const { state } = require("../../shared/state");
 const { nativeCurrencyByChainId } = require("../../shared/networks");
 const { formatEther, formatUnits } = require("ethers");
 const { log, debugFetch } = require("../../shared/log");
+const { storedSettingIsOn } = require("../../shared/storedSettings");
 const { decodeCalldata } = require("./approval");
 
 /**
@@ -172,7 +173,8 @@ function render() {
         }
     }
 
-    // Hide calldata and raw data sections; always fetch full tx details
+    // Hide the calldata and raw data sections. loadFullTxDetails() shows them
+    // once it has their data.
     const calldataSection = $("tx-detail-calldata-section");
     if (calldataSection) calldataSection.classList.add("hidden");
     const rawDataSection = $("tx-detail-rawdata-section");
@@ -191,6 +193,12 @@ function render() {
         if (el) el.classList.add("hidden");
     }
 
+    // The block, network details, decoded details and raw data come from
+    // Blockscout. While the setting is off, this line says why none is shown.
+    $("tx-detail-blockscout-note").classList.toggle(
+        "hidden",
+        !!state.useBlockscout,
+    );
     loadFullTxDetails(tx.hash, tx.chainId);
 
     const isoStr = isoDate(tx.timestamp);
@@ -303,7 +311,12 @@ function populateOnChainDetails(txData, 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.
 async function loadFullTxDetails(txHash, chainId) {
+    if (!(await storedSettingIsOn("useBlockscout"))) return;
     const section = $("tx-detail-calldata-section");
     const actionEl = $("tx-detail-calldata-action");
     const detailsEl = $("tx-detail-calldata-details");
@@ -319,6 +332,7 @@ async function loadFullTxDetails(txHash, chainId) {
         );
         if (!resp.ok) return;
         const txData = await resp.json();
+        if (!(await storedSettingIsOn("useBlockscout"))) return;
 
         // Populate on-chain detail fields (block, nonce, gas, fee)
         populateOnChainDetails(txData, chainId);

src/popup/views/txStatus.js

@@ -14,6 +14,7 @@ const {
     displaySymbol,
     clearViewStack,
     tokenLabel,
+    blockscoutOffTokenNoteHtml,
     reviewedNetworkProvider,
 } = require("./helpers");
 const { state } = require("../../shared/state");
@@ -108,6 +109,10 @@ function startWait(txInfo, txHash, broadcastTime, pollNow) {
     }
     $("wait-tx-summary").textContent =
         txInfo.amount + (symbol ? " " + symbol : "");
+    $("wait-tx-token-note").innerHTML = blockscoutOffTokenNoteHtml(
+        txInfo.token,
+        txInfo.chainId,
+    );
     $("wait-tx-to").innerHTML = toAddressHtml(txInfo.to, txInfo.chainId);
     $("wait-tx-hash").innerHTML = txHashHtml(txHash, txInfo.chainId);
     attachCopyHandlers("view-wait-tx");
@@ -215,9 +220,10 @@ function showWait(txInfo, txHash) {
 // init and leaving wait-tx on screen with no back control. A non-numeric
 // broadcastTime leaves an unexitable wait counting "NaNs". txInfo.chainId picks
 // the node the receipt is asked of and the explorer the links open, so it has
-// to name a network. txInfo.token and txInfo.tokenSymbol are deliberately
-// unchecked: they are compared and coalesced rather than dereferenced, and
-// tokenSymbol is null for ETH.
+// to name a network. txInfo.token and txInfo.tokenSymbol are not checked here.
+// blockscoutOffTokenNoteHtml() shows no line for a token that is not text.
+// Everything else only compares and coalesces them, and tokenSymbol is null for
+// ETH.
 function restoreWait() {
     const d = state.viewData;
     if (!d || !d.pendingWait) return false;
@@ -282,6 +288,7 @@ function decodedDetailsHtml(decoded, chainId) {
             if (d.isToken) {
                 const sym = tokenLabel(d.address, chainId) || "Unknown token";
                 html += `<div class="font-bold">${escapeHtml(sym)}</div>`;
+                html += blockscoutOffTokenNoteHtml(d.address, chainId);
                 html += toAddressHtml(d.address, chainId);
             } else {
                 html += toAddressHtml(d.address, chainId);
@@ -345,6 +352,7 @@ function showError(txInfo, txHash, message) {
     state.viewData = {
         amount: txInfo.amount,
         symbol: symbol,
+        token: txInfo.token,
         to: txInfo.to,
         hash: txHash || null,
         message: message,
@@ -358,6 +366,10 @@ function renderError() {
     if (!d || !d.message) return;
     $("error-tx-summary").textContent =
         d.amount + (d.symbol ? " " + d.symbol : "");
+    $("error-tx-token-note").innerHTML = blockscoutOffTokenNoteHtml(
+        d.token,
+        d.chainId,
+    );
     $("error-tx-to").innerHTML = toAddressHtml(d.to, d.chainId);
     $("error-tx-message").textContent = d.message;
 

src/popup/views/welcome.js

@@ -1,7 +1,37 @@
-const { $ } = require("./helpers");
+// The first screen, shown while there is no wallet. It offers "Use Blockscout"
+// and "Check recipients on Etherscan", which Settings offers too. Both are off
+// until the user ticks them.
 
-function init(ctx) {
-    $("btn-welcome-add").addEventListener("click", ctx.showAddWalletView);
+const { $, showView } = require("./helpers");
+const { state, saveState } = require("../../shared/state");
+
+function show() {
+    $("welcome-use-blockscout").checked = state.useBlockscout;
+    $("welcome-check-recipients-on-etherscan").checked =
+        state.checkRecipientsOnEtherscan;
+    showView("welcome");
 }
 
-module.exports = { init };
+// Each change is made inside the save, holding the lock, as Settings makes it.
+function init(ctx) {
+    $("btn-welcome-add").addEventListener("click", ctx.showAddWalletView);
+
+    $("welcome-use-blockscout").addEventListener("change", async () => {
+        const on = $("welcome-use-blockscout").checked;
+        await saveState(() => {
+            state.useBlockscout = on;
+        });
+    });
+
+    $("welcome-check-recipients-on-etherscan").addEventListener(
+        "change",
+        async () => {
+            const on = $("welcome-check-recipients-on-etherscan").checked;
+            await saveState(() => {
+                state.checkRecipientsOnEtherscan = on;
+            });
+        },
+    );
+}
+
+module.exports = { init, show };

src/shared/balances.js

@@ -1,5 +1,10 @@
-// Balance fetching: ETH balances via RPC, ERC-20 token balances via
-// Blockscout, ENS reverse lookup via RPC.
+// Balance fetching:
+//
+//   - ETH balances, and the balances of the tokens the user tracks, via RPC
+//   - the other ERC-20 token balances and the holder counts via Blockscout,
+//     while the user has "Use Blockscout" on. Those balances are dropped when
+//     the setting is off.
+//   - ENS reverse lookup via RPC
 
 const {
     JsonRpcProvider,
@@ -17,6 +22,7 @@ const { LOW_HOLDER_THRESHOLD, parseHoldersCount } = require("./holders");
 const { isSpoofedSymbol } = require("./symbolSpoof");
 const { toDecimals } = require("./transferAmount");
 const { resolveTokenDecimals } = require("./approvalAmount");
+const { storedSettingIsOn } = require("./storedSettings");
 
 // Use a static network to skip auto-detection (which can fail and cause
 // "could not coalesce error" on some RPC endpoints like Cloudflare).
@@ -36,9 +42,18 @@ const { resolveTokenDecimals } = require("./approvalAmount");
 // ethers knows chains this wallet does not, so an id that is not one of ours
 // is a caller bug and must not resolve to a working provider for some other
 // chain.
+//
+// `disableCcipRead` keeps every ENS lookup on the RPC endpoint. A resolver can
+// say a name is resolved off-chain and give a web address for it. By default
+// ethers then fetches that address straight from the browser, sending the name
+// being looked up. For the reverse lookup of the user's addresses, the name sent
+// is the user's own (https://git.eeqj.de/sneak/AutistMask/issues/668). With the
+// flag set, such a name does not resolve.
 function getProvider(rpcUrl, networkId) {
     const net = Network.from(requireNetworkId(networkId).id);
-    return new JsonRpcProvider(rpcUrl, net, { staticNetwork: net });
+    const provider = new JsonRpcProvider(rpcUrl, net, { staticNetwork: net });
+    provider.disableCcipRead = true;
+    return provider;
 }
 
 function requireNetworkId(networkId) {
@@ -80,8 +95,16 @@ function rawUnits(value) {
 
 // Fetch token balances for a single address from Blockscout.
 // Returns [{ address, name, symbol, decimals, balance, holders }].
+//
+// 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 this returns an empty list, so
+// only tracked tokens are listed.
+//
 // Filters out spam: only shows tokens that are in the known token list,
-// explicitly tracked by the user, or have >= 1000 holders.
+// explicitly tracked by the user, or have >= 1000 holders. A tracked token's
+// balance is read through the RPC endpoint instead, and its row here gives that
+// entry its holder count and `decimals` (fetchTrackedTokenBalances()).
 //
 // `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
@@ -96,6 +119,7 @@ async function fetchTokenBalances(
     trackedTokens,
     signal,
 ) {
+    if (!(await storedSettingIsOn("useBlockscout"))) return [];
     try {
         const resp = await debugFetch(
             blockscoutUrl + "/addresses/" + address + "/token-balances",
@@ -105,6 +129,7 @@ async function fetchTokenBalances(
             return null;
         }
         const items = await resp.json();
+        if (!(await storedSettingIsOn("useBlockscout"))) return [];
         if (!Array.isArray(items)) return null;
 
         const trackedSet = new Set(
@@ -205,8 +230,96 @@ async function fetchTokenBalances(
     }
 }
 
-// Fetch ETH balances, ENS names, and ERC-20 token balances for all addresses.
+// The entries at `address` of the tokens the user tracks, shaped as
+// fetchTokenBalances() returns them, for the tokens the address holds.
+//
+// The balance is read with balanceOf through the RPC endpoint. The name and
+// symbol are the tracked token's. `decimals` and `holders` are those of
+// Blockscout's entry for the token in `explorerRequest`, this refresh's
+// fetchTokenBalances() for the address; while Blockscout fails they are kept
+// from the token's entry in `previous`, the address's entries before this
+// refresh. The balance is stated at the scale the screens read the token at
+// (resolveTokenDecimals()): the bundled list's, then the one the tracked token
+// records, then Blockscout's, as in fetchTokenBalances().
+//
+// A token whose balanceOf fails keeps its entry in `previous`, as a failed ETH
+// balance keeps its figure, or takes Blockscout's entry from this refresh when
+// it has none. The failure is logged. A balance of zero gets no entry, as a
+// zero Blockscout reports gets none: the balance lists take a tracked token's
+// 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().
+async function fetchTrackedTokenBalances(
+    provider,
+    address,
+    trackedTokens,
+    previous,
+    explorerRequest,
+    signal,
+) {
+    const listed = trackedTokens.filter(
+        (token) => !isSpoofedSymbol(token.symbol, token.address),
+    );
+    // Each token's balanceOf answer, or null where it failed.
+    const balances = await Promise.all(
+        listed.map(async (token) => {
+            try {
+                const contract = new Contract(
+                    token.address,
+                    ERC20_ABI,
+                    provider,
+                );
+                return await contract.balanceOf(address);
+            } catch (e) {
+                if (!signal?.aborted) {
+                    log.errorf(
+                        "token balance failed",
+                        address,
+                        token.address,
+                        e.shortMessage || e.message,
+                    );
+                }
+                return null;
+            }
+        }),
+    );
+    const explorerRows = await explorerRequest;
+    const reported = explorerRows ?? previous;
+
+    const rows = [];
+    listed.forEach((token, i) => {
+        const lower = token.address.toLowerCase();
+        const entryIn = (list) =>
+            list.find((row) => String(row.address).toLowerCase() === lower);
+        const raw = balances[i];
+        if (raw === null) {
+            const kept = entryIn(previous) || entryIn(explorerRows || []);
+            if (kept) rows.push(kept);
+            return;
+        }
+        if (raw === 0n) return;
+        const entry = entryIn(reported);
+        const decimals = entry ? entry.decimals : null;
+        const known = resolveTokenDecimals(lower, { trackedTokens });
+        const scale = known !== null ? known : decimals;
+        rows.push({
+            address: token.address,
+            name: token.name || "",
+            symbol: token.symbol || "???",
+            decimals: decimals,
+            // null when nothing knows the scale: a holding whose amount
+            // cannot be stated, never a zero.
+            balance: scale === null ? null : formatTokenBalance(raw, scale),
+            holders: entry ? entry.holders : null,
+        });
+    });
+    return rows;
+}
+
+// Fetch ETH balances, ENS names, and ERC-20 token balances for all addresses.
+// `trackedTokens` are the tokens tracked on the active network. `signal` is as
+// for fetchTokenBalances().
 async function refreshBalances(
     wallets,
     rpcUrl,
@@ -217,6 +330,8 @@ async function refreshBalances(
 ) {
     log.debugf("refreshBalances start, rpc:", urlOrigin(rpcUrl));
     const provider = getProvider(rpcUrl, networkId);
+    const tracked = trackedTokens || [];
+    const trackedSet = new Set(tracked.map((t) => t.address.toLowerCase()));
     const updates = [];
 
     for (const wallet of wallets) {
@@ -266,23 +381,43 @@ async function refreshBalances(
                     }),
             );
 
-            // ERC-20 token balances via Blockscout
+            // ERC-20 token balances: the tracked tokens' through the RPC
+            // endpoint, and from Blockscout the tokens the user has not
+            // tracked. When Blockscout fails, the untracked rows from before
+            // this refresh stay. While "Use Blockscout" is off, there are no
+            // untracked rows. The Blockscout request is started first and
+            // handed to fetchTrackedTokenBalances() too, which waits for it
+            // after sending its balanceOf reads, so the two run side by side.
+            const previous = addr.tokenBalances || [];
+            const explorerRequest = fetchTokenBalances(
+                addr.address,
+                blockscoutUrl,
+                tracked,
+                signal,
+            );
             updates.push(
-                fetchTokenBalances(
-                    addr.address,
-                    blockscoutUrl,
-                    trackedTokens,
-                    signal,
-                ).then((balances) => {
-                    if (balances !== null) {
-                        addr.tokenBalances = balances;
-                        log.debugf(
-                            "Token balances",
-                            addr.address,
-                            balances.length,
-                            "tokens",
-                        );
-                    }
+                Promise.all([
+                    fetchTrackedTokenBalances(
+                        provider,
+                        addr.address,
+                        tracked,
+                        previous,
+                        explorerRequest,
+                        signal,
+                    ),
+                    explorerRequest,
+                ]).then(([trackedRows, explorerRows]) => {
+                    const untrackedRows = (explorerRows ?? previous).filter(
+                        (row) =>
+                            !trackedSet.has(String(row.address).toLowerCase()),
+                    );
+                    addr.tokenBalances = trackedRows.concat(untrackedRows);
+                    log.debugf(
+                        "Token balances",
+                        addr.address,
+                        addr.tokenBalances.length,
+                        "tokens",
+                    );
                 }),
             );
         }
@@ -292,6 +427,20 @@ async function refreshBalances(
     log.debugf("refreshBalances done");
 }
 
+// Drops the balance of each token not in `trackedTokens` from every address.
+// Callers run it while "Use Blockscout" is off, since only Blockscout reports
+// those tokens.
+function dropUntrackedTokens(wallets, trackedTokens) {
+    const tracked = new Set(trackedTokens.map((t) => t.address.toLowerCase()));
+    for (const wallet of wallets) {
+        for (const addr of wallet.addresses || []) {
+            addr.tokenBalances = (addr.tokenBalances || []).filter((row) =>
+                tracked.has(String(row.address).toLowerCase()),
+            );
+        }
+    }
+}
+
 // Look up token metadata from its contract.
 // Calls symbol() and decimals() to verify it implements ERC-20.
 // `signal` is as for fetchTokenBalances().
@@ -410,6 +559,7 @@ async function scanForAddresses(xpub, rpcUrl, networkId, signal, gapLimit = 5) {
 module.exports = {
     fetchTokenBalances,
     refreshBalances,
+    dropUntrackedTokens,
     lookupTokenInfo,
     getProvider,
     scanForAddresses,

src/shared/browserApi.js

@@ -224,6 +224,19 @@ function storageRemove(keys) {
     return Promise.resolve(storage.remove(keys));
 }
 
+/**
+ * Call `listener` after every write to `storage.local`, whether this page,
+ * another page or the background made it, with what the write changed, as the
+ * browser reports it: `{ [key]: { oldValue, newValue } }`.
+ *
+ * @param {function(Object): void} listener
+ */
+function onStorageChanged(listener) {
+    namespaceMember("storage").onChanged.addListener((changes, areaName) => {
+        if (areaName === "local") listener(changes);
+    });
+}
+
 /**
  * Run `fn` while holding the browser's lock called `name`
  * (`navigator.locks`), and settle as `fn` settles. Every page of the extension
@@ -385,6 +398,7 @@ module.exports = {
     getPlatformInfo,
     hasBrowserNamespace,
     notify,
+    onStorageChanged,
     runtimeApi,
     sendMessage,
     sessionStorageGet,

src/shared/chainSwitch.js

@@ -1,8 +1,18 @@
-// Consolidated chain-switch handler for the popup.
+// The popup's network switch.
 //
-// Every state change required when the active network changes is
-// performed here so that callers (settings UI, future chain additions) all go
-// through a single code path.
+// A network switch reaches the popup's `state` in one of two ways:
+//
+// - onChainSwitch() below makes the switch the user picks in Settings, with
+//   applyChainSwitchFields() (chainSwitchFields.js).
+// - followStoredSettings() in src/popup/index.js takes a switch the background
+//   or another popup page saved, from the stored record, with
+//   takeStoredNetwork() (state.js), which copies it with
+//   copyChainSwitchFields() (chainSwitchFields.js).
+//
+// Both change `state` inside a save, holding the lock, and both reset the
+// popup's own caches through clearPopupCaches(), so a reset added there
+// reaches both. A field applyChainSwitchFields() sets has to be copied by
+// copyChainSwitchFields() too.
 //
 // Adding a new chain (e.g. ETC) requires only a new entry in
 // networks.js — no per-caller wiring is needed.
@@ -20,22 +30,32 @@
 const { applyChainSwitchFields } = require("./chainSwitchFields");
 const { clearPrices } = require("./prices");
 
+// The popup's own caches a network switch resets. Prices are chain-specific
+// (testnet tokens are worthless, ETC has different pricing, etc.). In-memory
+// and per bundle, so this is the popup's own cache — the only context that
+// ever fills it.
+function clearPopupCaches() {
+    clearPrices();
+}
+
 // Switch the active chain and reset all chain-specific cached state.
-// Returns the network configuration object for the new chain.
+// Returns the network configuration object for the new chain, or null when
+// `state` already has that network once the save holds the lock, and nothing
+// is switched.
+//
+// `state` is switched inside the save that stores the switch, holding the
+// 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.
 async function onChainSwitch(newNetworkId) {
     const { state, saveState } = require("./state");
-
-    const net = applyChainSwitchFields(state, newNetworkId);
-
-    // --- price cache ---
-    // Prices are chain-specific (testnet tokens are worthless,
-    // ETC has different pricing, etc.). In-memory and per bundle, so this is
-    // the popup's own cache — the only context that ever fills it.
-    clearPrices();
-
-    await saveState();
-
+    let net = null;
+    await saveState(() => {
+        if (state.networkId === newNetworkId) return false;
+        net = applyChainSwitchFields(state, newNetworkId);
+        clearPopupCaches();
+    });
     return net;
 }
 
-module.exports = { onChainSwitch };
+module.exports = { onChainSwitch, clearPopupCaches };

src/shared/chainSwitchFields.js

@@ -7,7 +7,7 @@
 // the singleton and saves; the background applies it to the detached record of
 // its own read-modify-write (src/background/state.js).
 //
-// Everything here is synchronous and touches nothing but the object it is
+// Everything here is synchronous and touches nothing but the objects it is
 // given: no storage, no caches, no imports beyond the network table. That is
 // what makes it usable on a record that has been read fresh from storage
 // microseconds earlier and is about to be written back.
@@ -76,4 +76,33 @@ function applyChainSwitchFields(s, newNetworkId) {
     return net;
 }
 
-module.exports = { applyChainSwitchFields };
+// Give `s` every field applyChainSwitchFields() sets, as `switched` holds it:
+// the popup takes a switch the background saved from the stored record this
+// way, rather than performing it again (takeStoredNetwork() in
+// src/shared/state.js). Balances are taken by address, and an address
+// `switched` does not have keeps none.
+function copyChainSwitchFields(s, switched) {
+    s.networkEndpoints = switched.networkEndpoints;
+    s.networkTrackedTokens = switched.networkTrackedTokens;
+    s.trackedTokens = switched.trackedTokens;
+    s.networkId = switched.networkId;
+    s.rpcUrl = switched.rpcUrl;
+    s.blockscoutUrl = switched.blockscoutUrl;
+    s.lastBalanceRefresh = switched.lastBalanceRefresh;
+    s.tokenHolderCache = switched.tokenHolderCache;
+    s.fraudContracts = switched.fraudContracts;
+
+    const stored = new Map();
+    for (const wallet of switched.wallets) {
+        for (const addr of wallet.addresses) stored.set(addr.address, addr);
+    }
+    for (const wallet of s.wallets) {
+        for (const addr of wallet.addresses) {
+            const got = stored.get(addr.address);
+            addr.balance = got ? got.balance : "0";
+            addr.tokenBalances = got ? got.tokenBalances : [];
+        }
+    }
+}
+
+module.exports = { applyChainSwitchFields, copyChainSwitchFields };

src/shared/etherscanLabels.js

@@ -3,6 +3,7 @@
 // This is a best-effort enrichment: network failures return null silently.
 
 const { networkByChainId } = require("./networks");
+const { storedSettingIsOn } = require("./storedSettings");
 
 // Patterns in the page title that indicate a flagged address.
 // Title format: "Fake_Phishing184810 | Address: 0x... | Etherscan"
@@ -78,12 +79,19 @@ function parseEtherscanPage(html) {
  * when it is omitted: etherscan.io on mainnet, sepolia.etherscan.io on
  * Sepolia.
  *
+ * While the stored "Check recipients on Etherscan" is off, Etherscan is not
+ * asked. An answer that lands after the setting went off is dropped
+ * (src/shared/storedSettings.js). Either way the answer is null.
+ *
  * @param {string} address - Ethereum address to check.
  * @param {string} [chainId] - Chain id of the network to look it up on.
  * @returns {Promise<{type: string, message: string, severity: string}|null>}
  */
 async function checkEtherscanLabel(address, chainId) {
     try {
+        if (!(await storedSettingIsOn("checkRecipientsOnEtherscan"))) {
+            return null;
+        }
         // Lazy require to avoid pulling in chrome.storage at module scope
         // (which breaks unit tests that only exercise parseEtherscanPage).
         const { currentNetwork } = require("./state");
@@ -94,6 +102,9 @@ async function checkEtherscanLabel(address, chainId) {
         });
         if (!resp.ok) return null;
         const html = await resp.text();
+        if (!(await storedSettingIsOn("checkRecipientsOnEtherscan"))) {
+            return null;
+        }
         const result = parseEtherscanPage(html);
         if (result.isPhishing) {
             return {

src/shared/persistedState.js

@@ -48,6 +48,17 @@ const DEFAULT_STATE = {
     hideDustTransactions: true,
     dustThresholdGwei: 100000,
     utcTimestamps: false,
+    // "Use Blockscout" and "Check recipients on Etherscan" in Settings. Each
+    // setting applies to every network. Both are off until the user turns them
+    // on. With "Use Blockscout" on, Blockscout is sent the user's addresses and
+    // the hash of each transaction opened. With "Check recipients on
+    // Etherscan" on, Etherscan is sent the recipient's address and nothing
+    // else.
+    useBlockscout: false,
+    checkRecipientsOnEtherscan: false,
+    // "Allow weak passwords" in Settings. While it is off, AddWallet refuses a
+    // password shorter than 12 characters.
+    allowWeakPasswords: false,
     fraudContracts: [],
     tokenHolderCache: {},
     theme: "system",
@@ -406,6 +417,13 @@ function normalizePersisted(saved) {
             : 100000;
     out.utcTimestamps =
         saved.utcTimestamps !== undefined ? saved.utcTimestamps : false;
+    // Anything but true is off: each setting lets a request reach another
+    // service.
+    out.useBlockscout = saved.useBlockscout === true;
+    out.checkRecipientsOnEtherscan = saved.checkRecipientsOnEtherscan === true;
+    // Anything but true is off: the setting lets AddWallet accept a short
+    // password.
+    out.allowWeakPasswords = saved.allowWeakPasswords === true;
     // A list of contract addresses, floored the same way: send.js builds its
     // fraud set as `(state.fraudContracts || []).map((a) => a.toLowerCase())`
     // and filterTransactions() maps the same list through normalizeAddress(),

src/shared/state.js

@@ -23,6 +23,7 @@
 // guarantee.
 
 const { networkById } = require("./networks");
+const { copyChainSwitchFields } = require("./chainSwitchFields");
 const {
     DEFAULT_STATE,
     PERSISTED_FIELDS,
@@ -125,8 +126,10 @@ function currentNetwork() {
 }
 
 // The persisted fields as this page held them when its last loadState()
-// finished, or when its last successful saveState() began. saveState() diffs
-// the live state against this to find only the fields THIS page changed since.
+// 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.
 //
 // Deep-cloned, not a reference: callers mutate persisted objects and arrays
 // in place (state.wallets.push(...)), and a reference baseline would mutate
@@ -466,7 +469,11 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 // exists to remove, just delayed and confined to one page instead of two
 // (caught by tests/txStatus.test.js). A page's live picture of a field it
 // does not own goes on being whatever its last loadState() saw, same as
-// before this fix; only the persisted record is guaranteed current.
+// before this fix; only the persisted record is guaranteed current. Three
+// fields are the exceptions: the network, "Use Blockscout" and "Check
+// recipients on Etherscan". Through `beforeWrite`, the popup takes a change to
+// any of them that another context saved (followStoredSettings() in
+// src/popup/index.js).
 async function saveStateOnce(beforeWrite) {
     const result = await storageGet("autistmask");
     // The record in storage right now is about to be merged into and written
@@ -574,9 +581,7 @@ function reportSaveFailure(err) {
 // Each save runs start to finish holding the lock every write of the stored
 // record takes (withLock() in src/shared/browserApi.js), so no write by
 // another page or the background lands between its read and its write and is
-// lost (https://git.eeqj.de/sneak/AutistMask/issues/641). A page in a Firefox
-// private window is the exception: Firefox gives it locks of its own (README,
-// "Stored state and its version").
+// lost (https://git.eeqj.de/sneak/AutistMask/issues/641).
 //
 // The same lock orders this page's own saves. showView() calls saveState() on
 // every navigation without awaiting it, so two saves from one page can be
@@ -597,6 +602,17 @@ function saveState(beforeWrite) {
     return turn;
 }
 
+// Give this page the network switch held by `stored`, a record a save of this
+// page has just read (followStoredSettings() in src/popup/index.js calls this
+// from `beforeWrite`), in `state` and in `baseline` alike, as loadState() does
+// with a whole record. The switch is then not this page's own change, even when
+// that save fails to write: a later switch back to the previous network still
+// differs from `baseline`, and is stored.
+function takeStoredNetwork(stored) {
+    copyChainSwitchFields(rawState, stored);
+    copyChainSwitchFields(baseline, structuredClone(stored));
+}
+
 // 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
@@ -642,6 +658,7 @@ module.exports = {
     state,
     saveState,
     onSaveFailure,
+    takeStoredNetwork,
     loadState,
     currentAddress,
     currentNetwork,

src/shared/storedSettings.js

@@ -0,0 +1,27 @@
+// Reads "Use Blockscout" or "Check recipients on Etherscan" from the stored
+// profile.
+//
+// Before each request that sends the user's data to Blockscout or Etherscan, the
+// wallet reads that service's setting from storage. The wallet reads the setting
+// again when the answer lands. While the setting is off, no such request is
+// made, and an answer that lands after the setting went off is dropped. A page's
+// own copy of the setting is not used, because another page may have just
+// changed it.
+
+const { storageGet } = require("./browserApi");
+const { normalizePersisted } = require("./persistedState");
+
+// Whether the setting `name` is on in the stored profile. `name` is
+// "useBlockscout" or "checkRecipientsOnEtherscan". The profile is read through
+// normalizePersisted(), as a load reads it, so only a stored true is on. A
+// failed read counts as off.
+async function storedSettingIsOn(name) {
+    try {
+        const { autistmask } = await storageGet("autistmask");
+        return normalizePersisted(autistmask)[name];
+    } catch {
+        return false;
+    }
+}
+
+module.exports = { storedSettingIsOn };

src/shared/transactions.js

@@ -21,6 +21,7 @@ const { toDecimals } = require("./transferAmount");
 // detail view is the authoritative record and already shows exact precision.
 const { truncateAmount: formatTxValue } = require("./amountDisplay");
 const { routerRelease } = require("./uniswap");
+const { storedSettingIsOn } = require("./storedSettings");
 
 // Ethereum addresses are case-insensitive: EIP-55 mixed case is a checksum
 // over the address, not part of its identity.  Every address comparison in
@@ -235,12 +236,17 @@ function mergeTransactions(txs, tokenTransfers) {
 // `chainId` is the chain id of the network `blockscoutUrl` serves. Every entry
 // carries it, and a native entry is labelled with that network's
 // `nativeCurrency` from networks.js (`ETH`, `SepoliaETH`).
+//
+// 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 the answer is an empty list.
 async function fetchRecentTransactions(
     address,
     blockscoutUrl,
     chainId,
     count = 25,
 ) {
+    if (!(await storedSettingIsOn("useBlockscout"))) return [];
     log.debugf("fetchRecentTransactions", address);
     const addrLower = normalizeAddress(address);
 
@@ -271,6 +277,7 @@ async function fetchRecentTransactions(
 
     const txJson = txResp.ok ? await txResp.json() : {};
     const ttJson = ttResp.ok ? await ttResp.json() : {};
+    if (!(await storedSettingIsOn("useBlockscout"))) return [];
 
     const txs = mergeTransactions(
         (txJson.items || []).map((tx) => parseTx(tx, addrLower, chainId)),

src/shared/uniswap.js

@@ -953,7 +953,9 @@ function totalAmount(amounts) {
 // 2. Amount is the amountIn of the swap action that spends Token In. If
 //    several exact-in actions spend it, each with a stated amount, it is
 //    their sum; in any other case there is none. Min. received is the same
-//    for amountOutMin and the actions that buy Token Out.
+//    for amountOutMin and the actions that buy Token Out, except that there
+//    is none when a swap action in the step also spends Token Out: the step
+//    then does not pay out all that those actions buy.
 // 3. If any swap action in the step cannot be read, only SETTLE, SETTLE_ALL,
 //    TAKE and TAKE_ALL name the sides, and there is no Amount or Min.
 //    received.
@@ -1187,11 +1189,13 @@ function decodeV4Swap(input) {
         const boughtOnly = currenciesNotIn(bought, spent);
         if (present(takeToken) || boughtOnly.length === 1) {
             tokenOut = present(takeToken) ? takeToken : boughtOnly[0];
-            amountOutMin = totalAmount(
-                swaps
-                    .filter((s) => s.tokenOut === tokenOut)
-                    .map((s) => s.amountOutMin),
-            );
+            if (!spent.includes(tokenOut)) {
+                amountOutMin = totalAmount(
+                    swaps
+                        .filter((s) => s.tokenOut === tokenOut)
+                        .map((s) => s.amountOutMin),
+                );
+            }
         }
 
         return {
@@ -1234,9 +1238,11 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         let inputToken = null;
         let inputAmount = null;
         let inputEstablished = false;
-        // Whether the user pays the V4 step that set the input side any of
-        // its input currency (see decodeV4Swap()). Only a V4 step can set the
-        // input side with no amount, the one case in which this is read.
+        // Whether the user pays the step that set the input side: a V2 or V3
+        // swap step with `payerIsUser` true, a V4 step the user pays some of
+        // its input currency (see decodeV4Swap()), or a WRAP_ETH, whose ETH
+        // comes from the transaction's value. A step paid from the router
+        // takes nothing from the sender.
         let inputPaidByUser = false;
         // The last PERMIT2_PERMIT this decoder read before a step set the
         // input side, or null (see permitStands after the loop).
@@ -1353,8 +1359,9 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         };
         // A PERMIT2_PERMIT or PERMIT2_PERMIT_BATCH at `step` whose input this
         // decoder cannot read may let any spender take any amount of any
-        // token: one line says so, and there is no Amount line, whose figure
-        // may then be too low.
+        // token: one line says so, there is no Amount line, whose figure may
+        // then be too low, and the minimum reads Min. paid out (see
+        // toAnotherSpender).
         const permitUnread = (step) => {
             permits.push({ token: null, amount: null, spender: null, step });
             stepsUnread.push(step);
@@ -1622,6 +1629,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     if (s) {
                         if (!inputEstablished) {
                             setInputOnce(s.tokenIn, s.amountIn);
+                            inputPaidByUser = s.payerIsUser;
                         } else if (s.payerIsUser) {
                             addUserPaid(s.tokenIn, s.amountIn);
                         }
@@ -1645,6 +1653,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     if (s) {
                         if (!inputEstablished) {
                             setInputOnce(s.tokenIn, s.amountIn);
+                            inputPaidByUser = s.payerIsUser;
                         } else if (s.payerIsUser) {
                             addUserPaid(s.tokenIn, s.amountIn);
                         }
@@ -1676,6 +1685,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     if (s) {
                         if (!inputEstablished) {
                             setInputOnce(s.tokenIn, s.amountInMax);
+                            inputPaidByUser = s.payerIsUser;
                         } else if (s.payerIsUser) {
                             addUserPaid(s.tokenIn, s.amountInMax);
                         }
@@ -1771,10 +1781,13 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                 } else if (command === "WRAP_ETH") {
                     const w = decodeWrapEth(inputs[i]);
                     if (w) {
-                        setInputOnce(
-                            "0x0000000000000000000000000000000000000000",
-                            w.amount,
-                        );
+                        if (!inputEstablished) {
+                            setInputOnce(
+                                "0x0000000000000000000000000000000000000000",
+                                w.amount,
+                            );
+                            inputPaidByUser = true;
+                        }
                         addPayee(w.recipient);
                         // CONTRACT_BALANCE wraps all the router's ETH.
                         if (w.amount === CONTRACT_BALANCE) {
@@ -2021,8 +2034,9 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // Every other PERMIT2_PERMIT leaves Token In and the Amount line as
         // they read with no permit, and gets lines of its own below. A step
         // that may take from the sender what this decoder did not read leaves
-        // no figure, permit or not (see spentUnread()), and so does a permit
-        // or batch whose input it cannot read (see permitUnread()). An
+        // no figure, permit or not (see spentUnread()), and so do a permit
+        // or batch whose input it cannot read (see permitUnread()) and an
+        // allowance of Token In to another spender (see toAnotherSpender). An
         // EXECUTE_SUB_PLAN step leaves both sides unknown (below).
         const stepCommands = Array.from(
             commandsBytes,
@@ -2041,9 +2055,10 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // (see spentUnread()), or a token it does not know.
         const spentFromSender = [];
         let total = null;
-        // The takes `total` adds up, each a quantity, as { token, amount }.
-        // When there is no Amount line, each gets lines of its own (see
-        // below).
+        // The takes from the sender that `total` adds up, each a quantity, as
+        // { token, amount }. When there is no Amount line, each gets lines of
+        // its own (see below). The amount of a step that set the input side
+        // and is paid from the router counts in `total` but is not among them.
         const inTotal = [];
         // Whether the step that set the input side counts as a take from the
         // sender, which may get lines of its own. The amount it stated counts
@@ -2057,7 +2072,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         let firstTakeUnstated = null;
         if (!permitStands || sameAddress(inputToken, permit.token)) {
             total = inputAmount;
-            if (typeof inputAmount === "bigint") {
+            if (typeof inputAmount === "bigint" && inputPaidByUser) {
                 inTotal.push({ token: inputToken, amount: inputAmount });
             }
             if (hasFirstTake && !present(inputAmount)) {
@@ -2207,16 +2222,30 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             return amountText(amount, info);
         };
 
+        // Each allowance to a spender other than the router. Code that a step
+        // runs, such as a V4 pool's hook or a token's own code, can call that
+        // spender, which can then take up to the allowance from the sender
+        // before the transaction ends. A permit or batch this decoder could
+        // not read may be to any spender, of any token.
+        const toAnotherSpender = permits.filter(
+            (p) => !sameAddress(p.spender, toAddress),
+        );
+
         // A null token in `spentFromSender`, a step this decoder did not read
-        // or a token it does not know, and one in `permits`, a permit or
-        // batch it could not read, leave no Amount figure, which may then be
+        // or a token it does not know, and an allowance to another spender
+        // that may be of Token In, leave no Amount figure, which may then be
         // too low. With no Amount line, each take the total adds up gets
         // lines of its own, first, so that every amount this decoder read is
         // shown.
         if (
             present(inputAmount) &&
             spentFromSender.every((s) => present(s.token)) &&
-            permits.every((p) => present(p.token))
+            toAnotherSpender.every(
+                (p) =>
+                    present(p.token) &&
+                    present(inputToken) &&
+                    !sameAddress(p.token, inputToken),
+            )
         ) {
             const amount = spentText(inputAmount, inInfo);
             details.push({
@@ -2337,9 +2366,10 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // step pays the bridge, when one moves the sender's tokens into the
         // router, when a token stays in the router, and when a payout could
         // not be read. The output is received by the sender only when some
-        // step pays the sender and there is no such line. When no step names
-        // anyone paid, one line says so. `paidTo` holds these lines and the
-        // token line after each line about a token in the router.
+        // step pays the sender, there is no such line, and no allowance goes
+        // to another spender (see toAnotherSpender). When no step names anyone
+        // paid, one line says so. `paidTo` holds these lines and the token
+        // line after each line about a token in the router.
         const outputHeld =
             present(outputToken) && heldByRouter.has(outputToken.toLowerCase());
         const paidTo = paidElsewhere.map((address) => ({
@@ -2386,7 +2416,10 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         if (payeeUnread) {
             paidTo.push({ label: "Paid to", value: UNDECODED_CURRENCY });
         }
-        const received = paidToSender && paidTo.length === 0;
+        const received =
+            paidToSender &&
+            paidTo.length === 0 &&
+            toAnotherSpender.length === 0;
         if (!paidToSender && paidTo.length === 0) {
             paidTo.push({ label: "Paid to", value: UNNAMED_CURRENCY });
         }

tests/alarms.test.js

@@ -41,6 +41,8 @@ jest.mock("../src/shared/balances", () => ({
     refreshBalances: jest.fn(async () => {
         mockBalanceRefreshAt.push(Date.now());
     }),
+    dropUntrackedTokens: jest.requireActual("../src/shared/balances")
+        .dropUntrackedTokens,
     getProvider: jest.fn(() => ({})),
 }));
 

tests/allowWeakPasswords.test.js

@@ -0,0 +1,87 @@
+// "Allow weak passwords" in Settings is off until the user ticks it. While it
+// is off, AddWallet refuses a password shorter than 12 characters. While it is
+// on, AddWallet accepts any password that is not empty
+// (https://git.eeqj.de/sneak/AutistMask/issues/674). These boot the real popup,
+// set the checkbox in Settings as the user does, and then add a wallet.
+
+jest.mock("../src/shared/vault", () => ({
+    decryptWithPassword: jest.fn(),
+    encryptWithPassword: jest.fn(async () => ({
+        salt: "salt",
+        nonce: "nonce",
+        ciphertext: "ciphertext",
+    })),
+}));
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+} = require("./support/popupBoot");
+
+const CHECKBOX = "settings-allow-weak-passwords";
+const ERROR = "add-wallet-password-error";
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+// Boots a popup that holds one wallet and opens Settings, where the checkbox
+// starts unticked. Ticks it when `allow` is true. Then opens AddWallet and
+// presses the die for a recovery phrase.
+async function openAddWallet(allow) {
+    const page = await bootPopup(unversionedValidProfile());
+    await page.click("btn-settings");
+    const checkbox = page.node(CHECKBOX);
+    expect(checkbox.checked).toBe(false);
+    if (allow) {
+        checkbox.checked = true;
+        for (const fn of checkbox.listeners.change) await fn();
+        expect(page.storage.read("autistmask").allowWeakPasswords).toBe(true);
+    }
+    await page.click("btn-main-add-wallet");
+    await page.click("btn-generate-phrase");
+    return page;
+}
+
+// Types `password` into both password fields and presses Import.
+async function importWith(page, password) {
+    page.node("add-wallet-password").value = password;
+    page.node("add-wallet-password-confirm").value = password;
+    await page.click("btn-add-wallet-confirm");
+}
+
+function storedWalletCount(page) {
+    return page.storage.read("autistmask").wallets.length;
+}
+
+describe("Allow weak passwords", () => {
+    test("unticked: a password shorter than 12 characters is refused", async () => {
+        const page = await openAddWallet(false);
+        await importWith(page, "short");
+        expect(page.text(ERROR)).toBe(
+            "Password must be at least 12 characters.",
+        );
+        expect(storedWalletCount(page)).toBe(1);
+        expect(page.visibleViews()).toEqual(["add-wallet"]);
+    });
+
+    test("ticked: a password shorter than 12 characters is accepted", async () => {
+        const page = await openAddWallet(true);
+        await importWith(page, "short");
+        expect(page.text(ERROR)).toBe("");
+        expect(storedWalletCount(page)).toBe(2);
+        expect(page.visibleViews()).toEqual(["main"]);
+    });
+
+    test.each([false, true])(
+        "an empty password is refused (ticked: %s)",
+        async (allow) => {
+            const page = await openAddWallet(allow);
+            await importWith(page, "");
+            expect(page.text(ERROR)).toBe("Please choose a password.");
+            expect(storedWalletCount(page)).toBe(1);
+            expect(page.visibleViews()).toEqual(["add-wallet"]);
+        },
+    );
+});

tests/approvalAmount.test.js

@@ -84,6 +84,9 @@ function walletsHolding(token, decimals) {
 beforeEach(() => {
     state.trackedTokens = [];
     state.wallets = [];
+    // The approval screen reads the explorer's report only while "Use
+    // Blockscout" is on.
+    state.useBlockscout = true;
 });
 
 describe("resolveTokenDecimals", () => {

tests/approvalUseBlockscoutOff.test.js

@@ -0,0 +1,308 @@
+// While "Use Blockscout" is off, the approval screens, and the screens that
+// follow TxApproval, take a token's name and scale from the bundled list and
+// the tracked tokens alone (https://git.eeqj.de/sneak/AutistMask/issues/668).
+// A token missing from both gets a line under it. The line says Blockscout's
+// report of the user's balances is not used to name the token. While the
+// setting is on, Blockscout's report of the user's holding is a source too, as
+// before.
+//
+// Booted through the real popup entry point, as the approval window or as a
+// popup reopened onto SuccessTx, WaitTx or ErrorTx. The vault is mocked so that
+// no password has to be hashed: the stored secret decrypts to the test key
+// below.
+
+jest.mock("../src/shared/vault", () => ({
+    decryptWithPassword: jest.fn(),
+    encryptWithPassword: jest.fn(),
+}));
+
+const { Interface, Wallet } = require("ethers");
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+} = require("./support/popupBoot");
+
+// A published test key, never used for real funds.
+const SIGNER_KEY =
+    "0x59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d";
+const signer = new Wallet(SIGNER_KEY);
+const ORIGIN = "https://dapp.example";
+const RECIPIENT = "0x2222222222222222222222222222222222222222";
+const TX_HASH = "0x" + "ab".repeat(32);
+// Outside the bundled list, and not tracked.
+const TOKEN = "0xE2E0000000000000000000000000000000000E2e";
+// In the bundled list, at 6 decimals.
+const USDC = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
+
+const LINE =
+    'Blockscout\'s report of your balances is not used to name this token, because "Use Blockscout" is off in Settings.';
+
+// TOKEN as Blockscout reports the user's holding of it.
+const TOKEN_ROW = {
+    address: TOKEN,
+    name: "Novel",
+    symbol: "NOVEL",
+    decimals: "6",
+    balance: "5000.0",
+    holders: 5000,
+};
+
+// A transfer of 5,000 of a 6-decimal token to RECIPIENT.
+const TRANSFER_DATA = new Interface([
+    "function transfer(address to, uint256 amount)",
+]).encodeFunctionData("transfer", [RECIPIENT, 5000000000n]);
+
+// An EIP-2612 permit letting RECIPIENT take 5,000 of TOKEN.
+const PERMIT = {
+    types: {
+        EIP712Domain: [
+            { name: "name", type: "string" },
+            { name: "chainId", type: "uint256" },
+            { name: "verifyingContract", type: "address" },
+        ],
+        Permit: [
+            { name: "owner", type: "address" },
+            { name: "spender", type: "address" },
+            { name: "value", type: "uint256" },
+            { name: "nonce", type: "uint256" },
+            { name: "deadline", type: "uint256" },
+        ],
+    },
+    primaryType: "Permit",
+    domain: { name: "Novel", chainId: 1, verifyingContract: TOKEN },
+    message: {
+        owner: signer.address,
+        spender: RECIPIENT,
+        value: "5000000000",
+        nonce: "0",
+        deadline: "1790000000",
+    },
+};
+
+// The stored profile: the user's one address holds `tokenBalances`.
+function profile(useBlockscout, tokenBalances, extra) {
+    return unversionedValidProfile({
+        useBlockscout,
+        wallets: [
+            {
+                type: "key",
+                name: "Wallet 1",
+                encryptedSecret: "encrypted-key",
+                addresses: [
+                    {
+                        address: signer.address,
+                        balance: "1.0",
+                        tokenBalances,
+                    },
+                ],
+            },
+        ],
+        activeAddress: signer.address,
+        allowedSites: { [signer.address]: [ORIGIN] },
+        ...extra,
+    });
+}
+
+// The approval window for the site's request. The request is a transfer sent to
+// `token`, or a signature request when `signParams` is given. The background
+// answers the signed transaction with `txResponse`.
+function bootApproval(stored, { token = TOKEN, signParams, txResponse } = {}) {
+    return bootPopup(stored, {
+        search: "?approval=approval-1",
+        runtime: {
+            connect: () => ({ postMessage: () => {} }),
+            sendMessage: (msg, reply) => {
+                if (msg.type === "AUTISTMASK_GET_APPROVAL") {
+                    reply({
+                        type: signParams ? "sign" : "tx",
+                        origin: ORIGIN,
+                        isPhishingDomain: false,
+                        approvedFrom: signer.address,
+                        signParams,
+                        approvedTx: {
+                            type: 2,
+                            from: signer.address,
+                            chainId: "0x1",
+                            nonce: "0x7",
+                            gasLimit: "0x30d40",
+                            maxPriorityFeePerGas: "0x3b9aca00",
+                            maxFeePerGas: "0x77359400",
+                            to: token,
+                            value: "0x0",
+                            data: TRANSFER_DATA,
+                            accessList: [],
+                        },
+                    });
+                } else if (msg.type === "AUTISTMASK_TX_RESPONSE") {
+                    reply(txResponse);
+                } else {
+                    reply(undefined);
+                }
+            },
+        },
+    });
+}
+
+beforeEach(() => {
+    // The page logs its failed RPC reads; the stub node in popupBoot.js
+    // answers none.
+    jest.spyOn(console, "error").mockImplementation(() => {});
+});
+
+afterEach(() => {
+    cleanupPopup();
+    jest.restoreAllMocks();
+});
+
+describe("TxApproval", () => {
+    test("has the line under a token it cannot name while Use Blockscout is off", async () => {
+        const page = await bootApproval(profile(false, []));
+        const details = page.node("approve-tx-decoded-details").innerHTML;
+        expect(details).toContain("Unknown token");
+        expect(details).toContain(LINE);
+        expect(details).toContain("5000000000 base units (decimals unknown)");
+        cleanupPopup();
+
+        // The bundled list names USDC, so there is nothing to say.
+        const bundled = await bootApproval(profile(false, []), {
+            token: USDC,
+        });
+        expect(
+            bundled.node("approve-tx-decoded-details").innerHTML,
+        ).not.toContain(LINE);
+        cleanupPopup();
+
+        const on = await bootApproval(profile(true, [TOKEN_ROW]));
+        const named = on.node("approve-tx-decoded-details").innerHTML;
+        expect(named).toContain("5000.0000 NOVEL");
+        expect(named).not.toContain(LINE);
+    });
+
+    test("names nothing from a Blockscout entry still in the balances while Use Blockscout is off", async () => {
+        const page = await bootApproval(profile(false, [TOKEN_ROW]));
+        const details = page.node("approve-tx-decoded-details").innerHTML;
+        expect(details).not.toContain("NOVEL");
+        expect(details).toContain("Unknown token");
+        expect(details).toContain(LINE);
+    });
+
+    test.each([
+        ["WaitTx", { txHash: TX_HASH }, "wait-tx"],
+        [
+            "ErrorTx",
+            { error: "The transaction could not be sent.", retryable: false },
+            "error-tx",
+        ],
+    ])(
+        "%s after it says so under the amount while Use Blockscout is off",
+        async (_name, txResponse, view) => {
+            const page = await bootApproval(profile(false, []), {
+                txResponse,
+            });
+            const { decryptWithPassword } = require("../src/shared/vault");
+            decryptWithPassword.mockResolvedValue(SIGNER_KEY);
+            page.node("approve-tx-password").value = "any password";
+            await page.click("btn-approve-tx");
+            expect(page.visibleViews()).toEqual([view]);
+            expect(page.node(view + "-token-note").innerHTML).toBe(
+                `<div class="text-xs text-muted">${LINE}</div>`,
+            );
+        },
+    );
+});
+
+test("SuccessTx says so under the decoded token while Use Blockscout is off", async () => {
+    const page = await bootPopup(
+        profile(false, [], {
+            currentView: "success-tx",
+            viewStack: ["main"],
+            viewData: {
+                amount: "5000000000 base units (decimals unknown)",
+                symbol: "?",
+                to: RECIPIENT,
+                hash: TX_HASH,
+                blockNumber: 21000000,
+                chainId: "0x1",
+                decoded: {
+                    name: "Token Transfer",
+                    description: "Transfer ERC-20 token",
+                    details: [
+                        {
+                            label: "Token",
+                            value: TOKEN,
+                            address: TOKEN,
+                            isToken: true,
+                        },
+                    ],
+                },
+            },
+        }),
+    );
+    expect(page.visibleViews()).toEqual(["success-tx"]);
+    const decoded = page.node("success-tx-decoded").innerHTML;
+    expect(decoded).toContain("Unknown token");
+    expect(decoded).toContain(LINE);
+});
+
+test.each([
+    [
+        "wait-tx",
+        {
+            pendingWait: {
+                hash: TX_HASH,
+                txInfo: {
+                    to: RECIPIENT,
+                    amount: "1",
+                    token: 42,
+                    chainId: "0x1",
+                },
+                broadcastTime: Date.now(),
+            },
+        },
+    ],
+    [
+        "error-tx",
+        {
+            amount: "1",
+            symbol: "?",
+            token: 42,
+            to: RECIPIENT,
+            hash: TX_HASH,
+            message: "The transaction failed.",
+            chainId: "0x1",
+        },
+    ],
+])(
+    "a popup reopened onto %s shows no line for a stored token that is not text",
+    async (view, viewData) => {
+        const page = await bootPopup(
+            profile(false, [], {
+                currentView: view,
+                viewStack: ["main"],
+                viewData,
+            }),
+        );
+        expect(page.pageErrors).toEqual([]);
+        expect(page.visibleViews()).toEqual([view]);
+        expect(page.node(view + "-token-note").innerHTML).toBe("");
+    },
+);
+
+test("SignApproval says so under a permit's token while Use Blockscout is off", async () => {
+    const signParams = {
+        method: "eth_signTypedData_v4",
+        typedData: JSON.stringify(PERMIT),
+        from: signer.address,
+    };
+    const page = await bootApproval(profile(false, []), { signParams });
+    const message = page.node("approve-sign-message").innerHTML;
+    expect(message).toContain("Unknown token");
+    expect(message).toContain(LINE);
+    cleanupPopup();
+
+    const on = await bootApproval(profile(true, [TOKEN_ROW]), { signParams });
+    const named = on.node("approve-sign-message").innerHTML;
+    expect(named).toContain("5000.0000 NOVEL");
+    expect(named).not.toContain(LINE);
+});

tests/approvalWindow.test.js

@@ -12,6 +12,7 @@ const {
     cleanupPopup,
     settle,
     unversionedValidProfile,
+    ADDRESS,
 } = require("./support/popupBoot");
 
 afterEach(cleanupPopup);
@@ -174,3 +175,136 @@ test("a connection prompt in the toolbar popup leaves the browser window alone",
     expect(windows.updates).toEqual([]);
     expect(env.pageErrors).toEqual([]);
 });
+
+// Each row holds a transaction or signature approval as the background
+// describes it, plus the element ids of the screen that shows it. `refusal` is
+// the message the background refuses a Reject with.
+const TX_AND_SIGN_APPROVALS = [
+    {
+        kind: "transaction",
+        view: "approve-tx",
+        reject: "btn-reject-tx",
+        error: "approve-tx-error",
+        type: "AUTISTMASK_TX_RESPONSE",
+        refusal: "This transaction is already being sent.",
+        approval: {
+            type: "tx",
+            approvedFrom: ADDRESS,
+            approvedTx: {
+                chainId: 1,
+                to: ADDRESS,
+                value: "0",
+                data: "0x",
+                gasLimit: "21000",
+                maxFeePerGas: "1000000000",
+                maxPriorityFeePerGas: "1000000000",
+                nonce: 0,
+            },
+        },
+    },
+    {
+        kind: "signature",
+        view: "approve-sign",
+        reject: "btn-reject-sign",
+        error: "approve-sign-error",
+        type: "AUTISTMASK_SIGN_RESPONSE",
+        refusal: "This request is already being signed.",
+        approval: {
+            type: "sign",
+            approvedFrom: ADDRESS,
+            signParams: {
+                method: "personal_sign",
+                message: "0x48656c6c6f",
+                from: ADDRESS,
+            },
+        },
+    },
+];
+
+// A closed transaction or signature window leaves its request pending
+// (https://git.eeqj.de/sneak/AutistMask/issues/673). So Reject closes the
+// window only once the background has the rejection. A message sent as the
+// window closes can be lost, and the request would stay pending although the
+// user rejected it.
+test.each(TX_AND_SIGN_APPROVALS)(
+    "Reject on a $kind approval closes the window only once the background has answered",
+    async ({ view, reject, type, approval }) => {
+        let describeApproval = null;
+        let answerReject = null;
+        const sent = [];
+        const env = await bootPopup(unversionedValidProfile(), {
+            search: "?approval=approval-1",
+            runtime: {
+                connect: () => ({ postMessage: () => {} }),
+                sendMessage: (msg, reply) => {
+                    if (msg.type === "AUTISTMASK_GET_APPROVAL") {
+                        describeApproval = reply;
+                    }
+                    if (msg.type === type) {
+                        sent.push(msg);
+                        answerReject = reply;
+                    }
+                },
+            },
+        });
+        describeApproval({
+            ...approval,
+            origin: "https://dapp.example",
+            isPhishingDomain: false,
+        });
+        await settle();
+        expect(env.visibleViews()).toEqual([view]);
+        const close = jest.fn();
+        globalThis.window.close = close;
+
+        const clicked = env.click(reject);
+        await settle();
+        expect(sent).toEqual([{ type, id: "approval-1", approved: false }]);
+        expect(close).not.toHaveBeenCalled();
+
+        answerReject(null);
+        await clicked;
+        expect(close).toHaveBeenCalledTimes(1);
+        expect(env.pageErrors).toEqual([]);
+    },
+);
+
+// After Confirm or Sign, the background refuses a Reject while the transaction
+// is being sent or the signature checked. The request is not rejected then, so
+// the window stays open and shows the background's message.
+test.each(TX_AND_SIGN_APPROVALS)(
+    "Reject on a $kind approval that the background refuses shows the background's message and keeps the window open",
+    async ({ view, reject, error, type, refusal, approval }) => {
+        let describeApproval = null;
+        let answerReject = null;
+        const env = await bootPopup(unversionedValidProfile(), {
+            search: "?approval=approval-1",
+            runtime: {
+                connect: () => ({ postMessage: () => {} }),
+                sendMessage: (msg, reply) => {
+                    if (msg.type === "AUTISTMASK_GET_APPROVAL") {
+                        describeApproval = reply;
+                    }
+                    if (msg.type === type) answerReject = reply;
+                },
+            },
+        });
+        describeApproval({
+            ...approval,
+            origin: "https://dapp.example",
+            isPhishingDomain: false,
+        });
+        await settle();
+        const close = jest.fn();
+        globalThis.window.close = close;
+
+        const clicked = env.click(reject);
+        await settle();
+        answerReject({ error: refusal, retryable: false });
+        await clicked;
+        expect(close).not.toHaveBeenCalled();
+        expect(env.visibleViews()).toEqual([view]);
+        expect(env.text(error)).toBe(refusal);
+        expect(env.pageErrors).toEqual([]);
+    },
+);

tests/backgroundApproval.test.js

@@ -241,10 +241,11 @@ function loadBackground(options) {
     let connectListener = null;
     const created = [];
     const removed = [];
-    // Every URL the background put on the browser action. A site approval
-    // raised through action.openPopup() opens no window at all, so this is
-    // the only place its id appears.
-    const actionPopups = [];
+    // Every URL the background put on the browser action. When a test gives
+    // the URL the action holds before the worker starts, that URL comes
+    // first. A site approval raised through action.openPopup() opens no
+    // window at all, so this is the only place its id appears.
+    const actionPopups = opts.toolbarPopup ? [opts.toolbarPopup] : [];
     const openPopup = jest.fn(() => Promise.resolve());
 
     global.chrome = {
@@ -774,10 +775,9 @@ describe("one transaction approval at a time", () => {
 
     // The user closes an approval window that looks hung while the attempt
     // behind it is still running, and that attempt then fails in a way that
-    // would normally leave the approval standing for a retry. There is no
-    // window left to retry in, so leaving it standing answers the requesting
-    // page never — and holds the slot for the life of the worker with it.
-    test("an approval whose window closed under a failed attempt is answered, and frees the next request", async () => {
+    // leaves the approval standing for a retry. The toolbar popup opens it, so
+    // the user can still retry it, and answering it frees the slot.
+    test("an approval whose window closed under a failed attempt is retried from the toolbar popup, and frees the next request", async () => {
         const stalled = deferred();
         const bg = loadBackground();
 
@@ -808,11 +808,28 @@ describe("one transaction approval at a time", () => {
 
         stalled.resolve();
         await settle();
-        expect(first.result()).toEqual({
-            error: { code: 4001, message: "User rejected the request." },
-        });
+        expect(first.result()).toBeNull();
+        expect(bg.actionPopups[bg.actionPopups.length - 1]).toBe(
+            "src/popup/index.html?approval=" + first.id(),
+        );
 
         bg.setStateReadHook(null);
+        bg.broadcastTransaction.mockResolvedValue({ hash: "0xfeed" });
+        bg.send(
+            {
+                type: "AUTISTMASK_TX_RESPONSE",
+                id: first.id(),
+                approved: true,
+                rawSignedTx: await signedAtNonce(NONCE),
+            },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+        expect(first.result()).toEqual({ result: "0xfeed" });
+        expect(bg.actionPopups[bg.actionPopups.length - 1]).toBe(
+            "src/popup/index.html",
+        );
+
         const second = bg.requestTx();
         await settle();
         expect(second.result()).toBeNull();
@@ -853,8 +870,10 @@ describe("one transaction approval at a time", () => {
         const first = bg.requestTx();
         await settle();
 
-        // The user closes the approval window, which rejects it.
-        bg.closeWindow(1);
+        bg.send(
+            { type: "AUTISTMASK_TX_RESPONSE", id: first.id(), approved: false },
+            { url: bg.fromPopup.url },
+        );
         await settle();
         expect(first.result()).toEqual({
             error: { code: 4001, message: "User rejected the request." },
@@ -897,7 +916,7 @@ describe("the worker keeps running while an approval is pending", () => {
         try {
             const bg = loadBackground();
             const calls = global.chrome.runtime.getPlatformInfo;
-            bg.requestTx();
+            const pending = bg.requestTx();
             await settle();
             expect(startTimer).toHaveBeenCalledTimes(1);
             expect(startTimer.mock.calls[0][1]).toBe(20000);
@@ -906,11 +925,23 @@ describe("the worker keeps running while an approval is pending", () => {
             tick();
             expect(calls).toHaveBeenCalledTimes(1);
 
-            // The user closes the approval window, which rejects it.
+            // A closed window leaves the approval pending, so the calls go on.
             bg.closeWindow(1);
             await settle();
             tick();
-            expect(calls).toHaveBeenCalledTimes(1);
+            expect(calls).toHaveBeenCalledTimes(2);
+
+            bg.send(
+                {
+                    type: "AUTISTMASK_TX_RESPONSE",
+                    id: pending.id(),
+                    approved: false,
+                },
+                { url: bg.fromPopup.url },
+            );
+            await settle();
+            tick();
+            expect(calls).toHaveBeenCalledTimes(2);
             expect(stopTimer).toHaveBeenCalledWith(1);
         } finally {
             startTimer.mockRestore();
@@ -1841,6 +1872,237 @@ describe("the interlock releases a failed attempt", () => {
     });
 });
 
+// A transaction or signature approval stays pending when its window closes.
+// The browser can close that window when the user clicks away from it, for
+// example to copy the password from a password manager. The toolbar popup then
+// opens the approval, and the user answers it there
+// (https://git.eeqj.de/sneak/AutistMask/issues/673).
+describe("a closed approval window leaves the request pending", () => {
+    // The URL the toolbar popup opens now.
+    function toolbarPopup(bg) {
+        return bg.actionPopups[bg.actionPopups.length - 1];
+    }
+
+    // The timer that keeps the worker running while an approval is pending is
+    // stubbed, so no test here leaves that timer running when it ends.
+    let keepRunningTimer;
+    beforeEach(() => {
+        keepRunningTimer = jest
+            .spyOn(global, "setInterval")
+            .mockImplementation(() => 1);
+    });
+    afterEach(() => {
+        keepRunningTimer.mockRestore();
+    });
+
+    test("the toolbar popup opens a closed transaction approval, and approving it there sends", async () => {
+        const bg = loadBackground();
+        const pending = bg.requestTx();
+        await settle();
+
+        bg.closeWindow(1);
+        await settle();
+        expect(pending.result()).toBeNull();
+        expect(toolbarPopup(bg)).toBe(
+            "src/popup/index.html?approval=" + pending.id(),
+        );
+
+        bg.broadcastTransaction.mockResolvedValue({ hash: "0xfeed" });
+        bg.send(
+            {
+                type: "AUTISTMASK_TX_RESPONSE",
+                id: pending.id(),
+                approved: true,
+                rawSignedTx: await signedAtNonce(NONCE),
+            },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+        expect(pending.result()).toEqual({ result: "0xfeed" });
+        expect(toolbarPopup(bg)).toBe("src/popup/index.html");
+    });
+
+    test("Reject in the toolbar popup answers 4001, and the toolbar popup opens the wallet again", async () => {
+        const bg = loadBackground();
+        const pending = bg.requestSign();
+        await settle();
+
+        bg.closeWindow(1);
+        await settle();
+        expect(pending.result()).toBeNull();
+        expect(toolbarPopup(bg)).toBe(
+            "src/popup/index.html?approval=" + pending.id(),
+        );
+
+        const reject = bg.send(
+            {
+                type: "AUTISTMASK_SIGN_RESPONSE",
+                id: pending.id(),
+                approved: false,
+            },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+        expect(pending.result()).toEqual({
+            error: { code: 4001, message: "User rejected the request." },
+        });
+        // The popup closes its window only once this answer arrives.
+        expect(reject.sendResponse).toHaveBeenCalledWith(null);
+        expect(toolbarPopup(bg)).toBe("src/popup/index.html");
+    });
+
+    test("with two closed, the toolbar popup opens the older one first, then the other", async () => {
+        const bg = loadBackground();
+        const sign = bg.requestSign();
+        await settle();
+        const signId = sign.id();
+        const tx = bg.requestTx();
+        await settle();
+
+        // The signature request is in window 1 and the transaction in window
+        // 2. The newer window is closed first.
+        bg.closeWindow(2);
+        bg.closeWindow(1);
+        await settle();
+        expect(toolbarPopup(bg)).toBe(
+            "src/popup/index.html?approval=" + signId,
+        );
+
+        bg.send(
+            { type: "AUTISTMASK_SIGN_RESPONSE", id: signId, approved: false },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+        expect(toolbarPopup(bg)).toBe(
+            "src/popup/index.html?approval=" + tx.id(),
+        );
+
+        const reject = bg.send(
+            { type: "AUTISTMASK_TX_RESPONSE", id: tx.id(), approved: false },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+        expect(tx.result()).toEqual({
+            error: { code: 4001, message: "User rejected the request." },
+        });
+        expect(reject.sendResponse).toHaveBeenCalledWith(null);
+        expect(toolbarPopup(bg)).toBe("src/popup/index.html");
+    });
+
+    // The user can close the window while the attempt after Confirm runs. That
+    // attempt answers the request, so meanwhile the toolbar popup opens the
+    // wallet. Opened from the toolbar, the approval would look unanswered.
+    test("when the window closes during an attempt that sends, the toolbar popup keeps opening the wallet", async () => {
+        const bg = loadBackground();
+        const pending = bg.requestTx();
+        await settle();
+
+        const inFlight = deferred();
+        bg.broadcastTransaction.mockReturnValue(inFlight.promise);
+        bg.send(
+            {
+                type: "AUTISTMASK_TX_RESPONSE",
+                id: pending.id(),
+                approved: true,
+                rawSignedTx: await signedAtNonce(NONCE),
+            },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+        bg.closeWindow(1);
+        await settle();
+        expect(toolbarPopup(bg)).toBe("src/popup/index.html");
+
+        inFlight.resolve({ hash: "0xfeed" });
+        await settle();
+        expect(pending.result()).toEqual({ result: "0xfeed" });
+        expect(toolbarPopup(bg)).toBe("src/popup/index.html");
+    });
+
+    test("when the window closes during an attempt that fails retryably, the toolbar popup opens the wallet until the attempt ends, then the approval", async () => {
+        const stalled = deferred();
+        const bg = loadBackground();
+        const pending = bg.requestTx();
+        await settle();
+
+        bg.setStateReadHook(async () => {
+            await stalled.promise;
+            throw new Error("The wallet data could not be read.");
+        });
+        bg.send(
+            {
+                type: "AUTISTMASK_TX_RESPONSE",
+                id: pending.id(),
+                approved: true,
+                rawSignedTx: await signedAtNonce(NONCE),
+            },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+        bg.closeWindow(1);
+        await settle();
+        expect(toolbarPopup(bg)).toBe("src/popup/index.html");
+
+        stalled.resolve();
+        await settle();
+        expect(pending.result()).toBeNull();
+        expect(toolbarPopup(bg)).toBe(
+            "src/popup/index.html?approval=" + pending.id(),
+        );
+
+        // A retry from the toolbar popup holds the approval again, so the
+        // toolbar popup opens the wallet while that retry runs.
+        bg.setStateReadHook(null);
+        const inFlight = deferred();
+        bg.broadcastTransaction.mockReturnValue(inFlight.promise);
+        bg.send(
+            {
+                type: "AUTISTMASK_TX_RESPONSE",
+                id: pending.id(),
+                approved: true,
+                rawSignedTx: await signedAtNonce(NONCE),
+            },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+        expect(toolbarPopup(bg)).toBe("src/popup/index.html");
+
+        inFlight.resolve({ hash: "0xfeed" });
+        await settle();
+        expect(pending.result()).toEqual({ result: "0xfeed" });
+        expect(toolbarPopup(bg)).toBe("src/popup/index.html");
+    });
+
+    test("an address switch still rejects a closed approval", async () => {
+        const bg = loadBackground();
+        const pending = bg.requestTx();
+        await settle();
+        bg.closeWindow(1);
+        await settle();
+        expect(pending.result()).toBeNull();
+
+        bg.send(
+            { type: "AUTISTMASK_ACTIVE_CHANGED" },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+        expect(pending.result()).toEqual({
+            error: { code: 4001, message: "User rejected the request." },
+        });
+        expect(toolbarPopup(bg)).toBe("src/popup/index.html");
+    });
+
+    // The worker can stop while an approval waits with its window closed. The
+    // approval is lost with the worker, but the toolbar popup keeps its URL.
+    // The next worker points the toolbar popup back at the wallet.
+    test("a worker that starts points the toolbar popup back at the wallet", () => {
+        const bg = loadBackground({
+            toolbarPopup: "src/popup/index.html?approval=lost-approval",
+        });
+        expect(toolbarPopup(bg)).toBe("src/popup/index.html");
+    });
+});
+
 // The claim is what makes one approval one broadcast, so it has to hold
 // against everything else that retires an approval, not just against a second
 // AUTISTMASK_TX_RESPONSE. Each of these paths used to resolve the waiting
@@ -1961,20 +2223,6 @@ describe("a claimed approval outlives every other retirement path", () => {
     });
 
     // The refusals above must not cost the rejection its ordinary meaning.
-    test("with no attempt running, closing the window still rejects", async () => {
-        const bg = loadBackground();
-        const pending = bg.requestTx();
-        await settle();
-
-        bg.closeWindow(1);
-        await settle();
-
-        expect(pending.result()).toEqual({
-            error: { code: 4001, message: "User rejected the request." },
-        });
-        expect(bg.broadcastTransaction).not.toHaveBeenCalled();
-    });
-
     test("with no attempt running, an active-address switch still rejects and closes", async () => {
         const bg = loadBackground();
         const pending = bg.requestTx();
@@ -2584,15 +2832,12 @@ describe("a site connection decided as the popup closes", () => {
         });
     });
 
-    // The `isSite &&` half of that skip, which is what keeps it from reaching
-    // a tx or sign approval. The popup connects its port in show() before it
-    // knows the approval's type, and the background sets portConnected without
-    // looking at the type either, so a tx approval in the fallback window
-    // carries the flag too. Without the conjunct the window event would skip
-    // it, windowClosed would never be set, releaseApproval() would never settle
-    // it, and the page would hang — the #271 regression this guard is written
-    // around.
-    test("a tx window closed with the port connected still rejects", async () => {
+    // That skip must not reach a tx or sign approval. The popup connects its
+    // port in show() before it knows the approval's type, and the background
+    // sets portConnected without looking at the type either, so a tx approval
+    // carries the flag too. If the window event skipped it, windowClosed would
+    // never be set, and the toolbar popup would never open the approval.
+    test("a tx window closed with the port connected is still opened by the toolbar popup", async () => {
         const bg = loadBackground();
         const pending = bg.requestTx();
         await settle();
@@ -2600,9 +2845,10 @@ describe("a site connection decided as the popup closes", () => {
         await settle();
         bg.closeWindow(1);
         await settle();
-        expect(pending.result()).toEqual({
-            error: { code: 4001, message: "User rejected the request." },
-        });
+        expect(pending.result()).toBeNull();
+        expect(bg.actionPopups[bg.actionPopups.length - 1]).toBe(
+            "src/popup/index.html?approval=" + pending.id(),
+        );
     });
 });
 
@@ -2994,13 +3240,14 @@ describe("where an approval window opens", () => {
         expect(bg.created[1].left).toBeUndefined();
         expect(bg.created[1].top).toBeUndefined();
 
-        // The request waits on the second window rather than failing:
-        // closing that window is refusing the prompt.
+        // The request waits on the second window rather than failing. Once
+        // that window closes, the toolbar popup opens the request.
         expect(sign.result()).toBeNull();
         bg.closeWindow(2);
         await settle();
-        expect(sign.result()).toEqual({
-            error: { code: 4001, message: "User rejected the request." },
-        });
+        expect(sign.result()).toBeNull();
+        expect(bg.actionPopups[bg.actionPopups.length - 1]).toBe(
+            "src/popup/index.html?approval=" + sign.id(),
+        );
     });
 });

tests/backgroundStateIsolation.test.js

@@ -142,6 +142,8 @@ function loadWorker(networkId, opts) {
         },
         refreshBalances:
             options.refreshBalances || jest.fn(async () => undefined),
+        dropUntrackedTokens: jest.requireActual("../src/shared/balances")
+            .dropUntrackedTokens,
     }));
     jest.doMock("../src/shared/phishingDomains", () => ({
         isPhishingDomain: () => false,
@@ -443,3 +445,54 @@ describe("a balance refresh under a network switch", () => {
         );
     });
 });
+
+describe("a balance refresh under a change of Use Blockscout", () => {
+    // Turning "Use Blockscout" off drops the tokens the user has not tracked
+    // (src/popup/views/settings.js). Blockscout may have answered a refresh
+    // just before. That refresh still saves its balances when it returns, but
+    // not those tokens. The same refresh in the popup is in
+    // tests/blockscoutEtherscanSettings.test.js.
+    test("a refresh that returns after Use Blockscout was turned off saves its balances without the untracked token", async () => {
+        const roundTrip = deferred();
+        const started = deferred();
+
+        const bg = loadWorker("mainnet", {
+            refreshBalances: async (wallets) => {
+                started.resolve();
+                await roundTrip.promise;
+                wallets[0].addresses[0].balance = "7.0";
+                wallets[0].addresses[0].tokenBalances = [
+                    {
+                        address: "0xAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",
+                        name: "Test Token",
+                        symbol: "TST",
+                        decimals: 18,
+                        balance: "5.0",
+                        holders: 50000,
+                    },
+                ];
+            },
+        });
+        global.chrome.storage.write("autistmask", {
+            ...bg.persisted(),
+            useBlockscout: true,
+        });
+
+        const refresh = bg.fireBalanceAlarm();
+        await started.promise;
+
+        // The user unticks "Use Blockscout" in Settings while the round trip
+        // is out.
+        global.chrome.storage.write("autistmask", {
+            ...bg.persisted(),
+            useBlockscout: false,
+        });
+
+        roundTrip.resolve();
+        await refresh;
+
+        const after = bg.persisted();
+        expect(after.wallets[0].addresses[0].balance).toBe("7.0");
+        expect(after.wallets[0].addresses[0].tokenBalances).toEqual([]);
+    });
+});

tests/balanceRefreshCancelled.test.js

@@ -18,6 +18,17 @@ const {
 const RPC_URL = "https://rpc.example.invalid";
 const EXPLORER_URL = "https://explorer.example.invalid/api/v2";
 const ADDRESS = "0x1111111111111111111111111111111111111111";
+const TRACKED = {
+    address: "0x7777777777777777777777777777777777777777",
+    symbol: "TRK",
+    decimals: 6,
+};
+
+// Blockscout is asked only while the stored "Use Blockscout" is on.
+const { makeStorageStub } = require("./support/storageStub");
+globalThis.chrome = {
+    storage: makeStorageStub({ autistmask: { useBlockscout: true } }),
+};
 
 const realFetch = globalThis.fetch;
 let logged;
@@ -30,9 +41,9 @@ beforeEach(() => {
     const failedToFetch = async () => {
         throw new TypeError("Failed to fetch");
     };
-    // The RPC calls (ETH balance, ENS name, and the scan's balance and
-    // transaction count) and the explorer request (token balances) all fail
-    // the same way.
+    // The RPC calls (ETH balance, ENS name, the tracked token's balance, and
+    // the scan's balance and transaction count) and the explorer request (the
+    // other token balances) all fail the same way.
     FetchRequest.registerGetUrl(failedToFetch);
     globalThis.fetch = jest.fn(failedToFetch);
 });
@@ -49,7 +60,7 @@ function refresh(signal) {
         wallets,
         RPC_URL,
         EXPLORER_URL,
-        [],
+        [TRACKED],
         "mainnet",
         signal,
     );
@@ -60,6 +71,7 @@ test("a failure while the popup is open is reported", async () => {
     for (const label of [
         "ETH balance failed",
         "ENS reverse failed",
+        "token balance failed",
         "fetchTokenBalances failed: Failed to fetch",
     ]) {
         expect(logged.some((line) => line.includes(label))).toBe(true);

tests/balanceRefreshNetworkSwitch.test.js

@@ -97,9 +97,9 @@ test("a refresh that returns after a switch in Settings writes nothing, and the
     );
 });
 
-// The stored record still holds Ethereum Mainnet while the refresh's save reads
-// it, so only this page's own network shows the switch.
-test("a refresh whose save is reading the stored record when the user switches in Settings writes nothing", async () => {
+// The switch is made only once the refresh's save, holding the lock, has
+// written Ethereum Mainnet's balances, and the switch then clears them.
+test("a refresh whose save is reading the stored record when the user switches in Settings leaves none of its balances stored", async () => {
     const page = await bootPopup(unversionedValidProfile());
     expect(page.pageErrors).toEqual([]);
     const { state } = require("../src/shared/state");
@@ -145,7 +145,8 @@ test("a refresh that returns after the background switched the network writes no
 
     const refresh = await holdRefresh(page);
     // The background writes the switch to Sepolia, as its updateState() does
-    // once the user approves a site's request. This page is not told.
+    // once the user approves a site's request. This page is not told of it
+    // yet.
     const record = page.storage.read("autistmask");
     applyChainSwitchFields(record, "sepolia");
     page.storage.write("autistmask", record);

tests/blockscoutEtherscanSettings.test.js

@@ -0,0 +1,848 @@
+// Blockscout and Etherscan are sent none of the user's data until the user
+// turns on a setting for each
+// (https://git.eeqj.de/sneak/AutistMask/issues/668). A new profile has "Use
+// Blockscout" and "Check recipients on Etherscan" both off. While a setting is
+// off, no request sends its service the user's data.
+//
+// One request still reaches Blockscout while "Use Blockscout" is off: the check
+// behind "Save" beside the Blockscout URL in Settings. That check asks the URL
+// only for `/stats` and sends none of the user's data.
+//
+// Before any other request to Blockscout or Etherscan, the wallet reads that
+// service's setting from storage, not the page's copy. The wallet reads the
+// setting again when the answer lands. So a change saved by another page
+// applies at once. An open page also takes such a change and draws its screens
+// again.
+//
+// Only Blockscout reports the tokens the user has not tracked. While "Use
+// Blockscout" is off, no address keeps them and no screen lists them.
+//
+// The functions that make the requests are driven directly, against a fetch()
+// that records every URL it is asked for. The screens are driven through the
+// real popup over a stored profile (tests/support/popupBoot.js). The fetch()
+// stub in popupBoot.js records the same way.
+
+"use strict";
+
+const { FetchRequest } = require("ethers");
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+    ADDRESS,
+    TOKEN_ADDRESS,
+} = require("./support/popupBoot");
+const { makeStorageStub } = require("./support/storageStub");
+const {
+    DEFAULT_STATE,
+    normalizePersisted,
+} = require("../src/shared/persistedState");
+const {
+    fetchTokenBalances,
+    refreshBalances,
+} = require("../src/shared/balances");
+const { fetchRecentTransactions } = require("../src/shared/transactions");
+const { getFullWarnings } = require("../src/shared/addressWarnings");
+const { checkEtherscanLabel } = require("../src/shared/etherscanLabels");
+const { HISTORY_OFF_TEXT, escapeHtml } = require("../src/popup/views/helpers");
+
+const RPC_URL = "https://rpc.example.invalid";
+const BLOCKSCOUT = "https://eth.blockscout.com/api/v2";
+const RECIPIENT = "0x2222222222222222222222222222222222222222";
+const TX_HASH = "0x" + "ab".repeat(32);
+const ZERO_WORD = "0x" + "0".repeat(64);
+
+// USDC, from the bundled list, as Blockscout reports a holding of it.
+const USDC_ROW = {
+    value: "5000000",
+    token: {
+        type: "ERC-20",
+        address_hash: "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
+        symbol: "USDC",
+        name: "USD Coin",
+        decimals: "6",
+        holders_count: "50000",
+    },
+};
+
+// A transfer of 1 ETH from RECIPIENT to ADDRESS, as Blockscout lists it in
+// ADDRESS's history.
+const HISTORY_ITEM = {
+    hash: TX_HASH,
+    block_number: 21000000,
+    timestamp: "2026-02-27T12:00:00.000Z",
+    from: { hash: RECIPIENT },
+    to: { hash: ADDRESS, is_contract: false },
+    value: "1000000000000000000",
+    method: null,
+    status: "ok",
+};
+
+// Etherscan's page for RECIPIENT, which labels it a phishing address.
+const PHISHING_PAGE =
+    "<html><head><title>Fake_Phishing1 | Address: " +
+    RECIPIENT +
+    " | Etherscan</title></head><body></body></html>";
+
+const realFetch = globalThis.fetch;
+
+afterEach(() => {
+    cleanupPopup();
+    jest.restoreAllMocks();
+});
+
+describe("a new profile", () => {
+    test("has both settings off", () => {
+        expect(DEFAULT_STATE.useBlockscout).toBe(false);
+        expect(DEFAULT_STATE.checkRecipientsOnEtherscan).toBe(false);
+        const loaded = normalizePersisted(undefined);
+        expect(loaded.useBlockscout).toBe(false);
+        expect(loaded.checkRecipientsOnEtherscan).toBe(false);
+    });
+
+    test("keeps either setting the user turned on", () => {
+        const loaded = normalizePersisted({
+            useBlockscout: true,
+            checkRecipientsOnEtherscan: true,
+        });
+        expect(loaded.useBlockscout).toBe(true);
+        expect(loaded.checkRecipientsOnEtherscan).toBe(true);
+    });
+});
+
+describe("where each request is made", () => {
+    // Every URL that fetch() was asked for, in order.
+    let asked;
+
+    // What Blockscout and Etherscan answer: USDC among ADDRESS's tokens,
+    // HISTORY_ITEM in its history, and PHISHING_PAGE for RECIPIENT.
+    function answer(url) {
+        return {
+            ok: true,
+            status: 200,
+            json: async () => {
+                if (url.endsWith("/token-balances")) return [USDC_ROW];
+                if (url.endsWith("/transactions")) {
+                    return { items: [HISTORY_ITEM] };
+                }
+                return { items: [] };
+            },
+            text: async () => PHISHING_PAGE,
+        };
+    }
+
+    async function recordAndAnswer(url) {
+        asked.push(String(url));
+        return answer(String(url));
+    }
+
+    beforeEach(() => {
+        asked = [];
+        globalThis.fetch = jest.fn(recordAndAnswer);
+    });
+
+    afterEach(() => {
+        globalThis.fetch = realFetch;
+        delete globalThis.chrome;
+    });
+
+    // Storage holds `profile` as the stored profile, or nothing when it is
+    // undefined.
+    function storing(profile) {
+        globalThis.chrome = {
+            storage: makeStorageStub(
+                profile === undefined ? {} : { autistmask: profile },
+            ),
+        };
+    }
+
+    test("Blockscout's token balances are asked for only while Use Blockscout is on", async () => {
+        storing({ useBlockscout: false });
+        expect(await fetchTokenBalances(ADDRESS, BLOCKSCOUT, [])).toEqual([]);
+        expect(asked).toEqual([]);
+
+        storing({ useBlockscout: true });
+        const rows = await fetchTokenBalances(ADDRESS, BLOCKSCOUT, []);
+        expect(rows.map((row) => row.symbol)).toEqual(["USDC"]);
+        expect(asked).toEqual([
+            BLOCKSCOUT + "/addresses/" + ADDRESS + "/token-balances",
+        ]);
+    });
+
+    test("the transaction history is asked for only while Use Blockscout is on", async () => {
+        storing({ useBlockscout: false });
+        expect(
+            await fetchRecentTransactions(ADDRESS, BLOCKSCOUT, "0x1"),
+        ).toEqual([]);
+        expect(asked).toEqual([]);
+
+        storing({ useBlockscout: true });
+        await fetchRecentTransactions(ADDRESS, BLOCKSCOUT, "0x1");
+        expect(asked.sort()).toEqual([
+            BLOCKSCOUT +
+                "/addresses/" +
+                ADDRESS +
+                "/token-transfers?type=ERC-20",
+            BLOCKSCOUT + "/addresses/" + ADDRESS + "/transactions",
+        ]);
+    });
+
+    test("the Etherscan label check is made only while the stored profile has Check recipients on Etherscan on", async () => {
+        const provider = {
+            getCode: async () => "0x",
+            getTransactionCount: async () => 1,
+            getBalance: async () => 0n,
+        };
+        const checkWith = async (profile) => {
+            storing(profile);
+            await getFullWarnings(RECIPIENT, provider, { chainId: "0x1" });
+        };
+
+        await checkWith(undefined);
+        await checkWith({ checkRecipientsOnEtherscan: false });
+        // Only a stored true is on, as when the profile is loaded.
+        await checkWith({ checkRecipientsOnEtherscan: "true" });
+        await checkWith({ checkRecipientsOnEtherscan: 42 });
+        expect(asked).toEqual([]);
+
+        await checkWith({ checkRecipientsOnEtherscan: true });
+        expect(asked).toEqual(["https://etherscan.io/address/" + RECIPIENT]);
+    });
+
+    // Asks with `setting` on in storage. Once every request is out, storage
+    // holds `after` for the setting, as when the user changes it here or on
+    // another page. Only then does each request get its answer.
+    async function answeredAfter(setting, after, ask) {
+        storing({ [setting]: true });
+        let release;
+        const held = new Promise((resolve) => {
+            release = resolve;
+        });
+        let requested;
+        const out = new Promise((resolve) => {
+            requested = resolve;
+        });
+        globalThis.fetch = jest.fn(async (url) => {
+            requested();
+            await held;
+            return recordAndAnswer(url);
+        });
+        const result = ask();
+        await out;
+        globalThis.chrome.storage.write("autistmask", { [setting]: after });
+        release();
+        return result;
+    }
+
+    // One row per request, giving:
+    //
+    //   - its name
+    //   - the setting that gates it
+    //   - how to make it
+    //   - its answer while that setting is off
+    test.each([
+        [
+            "Blockscout's token balances",
+            "useBlockscout",
+            () => fetchTokenBalances(ADDRESS, BLOCKSCOUT, []),
+            [],
+        ],
+        [
+            "the transaction history",
+            "useBlockscout",
+            () => fetchRecentTransactions(ADDRESS, BLOCKSCOUT, "0x1"),
+            [],
+        ],
+        [
+            "the Etherscan label check",
+            "checkRecipientsOnEtherscan",
+            () => checkEtherscanLabel(RECIPIENT, "0x1"),
+            null,
+        ],
+    ])(
+        "%s keeps an answer that lands while its setting is on, and drops one that lands after it went off",
+        async (_what, setting, ask, dropped) => {
+            expect(await answeredAfter(setting, true, ask)).not.toEqual(
+                dropped,
+            );
+            expect(await answeredAfter(setting, false, ask)).toEqual(dropped);
+        },
+    );
+
+    describe("a balance refresh", () => {
+        // The RPC endpoint answers every balance with zero. The ENS reverse
+        // lookup makes the only other calls, and it finds no resolver.
+        beforeEach(() => {
+            FetchRequest.registerGetUrl(async (req) => {
+                const body = JSON.parse(Buffer.from(req.body).toString("utf8"));
+                const reply = (r) => ({
+                    jsonrpc: "2.0",
+                    id: r.id,
+                    result: r.method === "eth_getBalance" ? "0x0" : ZERO_WORD,
+                });
+                const answer = Array.isArray(body)
+                    ? body.map(reply)
+                    : reply(body);
+                return {
+                    statusCode: 200,
+                    statusMessage: "OK",
+                    headers: { "content-type": "application/json" },
+                    body: Buffer.from(JSON.stringify(answer)),
+                };
+            });
+        });
+
+        afterEach(() => {
+            FetchRequest.registerGetUrl(FetchRequest.createGetUrlFunc());
+        });
+
+        // An address refreshed while "Use Blockscout" was on. It holds the USDC
+        // that Blockscout reported then.
+        function addressWithUsdc() {
+            return {
+                address: ADDRESS,
+                tokenBalances: [
+                    {
+                        address: USDC_ROW.token.address_hash,
+                        name: "USD Coin",
+                        symbol: "USDC",
+                        decimals: 6,
+                        balance: "5.0",
+                        holders: 50000,
+                    },
+                ],
+            };
+        }
+
+        async function refresh(addr, useBlockscout) {
+            storing({ useBlockscout });
+            await refreshBalances(
+                [{ addresses: [addr] }],
+                RPC_URL,
+                BLOCKSCOUT,
+                [],
+                "mainnet",
+            );
+        }
+
+        test("asks Blockscout nothing while Use Blockscout is off, and then lists no token the user has not tracked", async () => {
+            const addr = addressWithUsdc();
+            await refresh(addr, false);
+            expect(asked).toEqual([]);
+            expect(addr.tokenBalances).toEqual([]);
+        });
+
+        test("asks Blockscout for the token balances while Use Blockscout is on", async () => {
+            const addr = addressWithUsdc();
+            await refresh(addr, true);
+            expect(asked).toEqual([
+                BLOCKSCOUT + "/addresses/" + ADDRESS + "/token-balances",
+            ]);
+            expect(addr.tokenBalances.map((row) => row.symbol)).toEqual([
+                "USDC",
+            ]);
+        });
+    });
+});
+
+describe("the popup", () => {
+    // Every URL the booted page handed to fetch().
+    function fetched() {
+        return globalThis.fetch.mock.calls.map((call) => String(call[0]));
+    }
+
+    function blockscoutOrEtherscan(url) {
+        return url.includes("blockscout") || url.includes("etherscan");
+    }
+
+    beforeEach(() => {
+        // The screens below log their failed RPC reads; the stub node in
+        // popupBoot.js answers none.
+        jest.spyOn(console, "error").mockImplementation(() => {});
+    });
+
+    test("Home says why there is no history and only tracked tokens while Use Blockscout is off", async () => {
+        const page = await bootPopup(unversionedValidProfile());
+        expect(page.node("home-tx-list").innerHTML).toContain(
+            escapeHtml(HISTORY_OFF_TEXT),
+        );
+        expect(page.hidden("home-tokens-note")).toBe(false);
+        cleanupPopup();
+
+        const on = await bootPopup(
+            unversionedValidProfile({ useBlockscout: true }),
+        );
+        expect(on.node("home-tx-list").innerHTML).toContain(
+            "No transactions found.",
+        );
+        expect(on.hidden("home-tokens-note")).toBe(true);
+    });
+
+    // The transaction screen, as a reopened popup draws it.
+    function onTransactionScreen(extra) {
+        return unversionedValidProfile({
+            currentView: "transaction",
+            viewStack: ["main"],
+            selectedWallet: 0,
+            selectedAddress: 0,
+            viewData: {
+                tx: {
+                    hash: TX_HASH,
+                    from: ADDRESS,
+                    to: RECIPIENT,
+                    value: "1.0000",
+                    exactValue: "1.0",
+                    symbol: "ETH",
+                    timestamp: 1790000000,
+                    isError: false,
+                    direction: "sent",
+                    directionLabel: "Sent",
+                    contractAddress: null,
+                    chainId: "0x1",
+                },
+            },
+            ...extra,
+        });
+    }
+
+    test("TransactionDetail asks Blockscout for the transaction only while Use Blockscout is on", async () => {
+        const page = await bootPopup(onTransactionScreen());
+        expect(page.visibleViews()).toEqual(["transaction"]);
+        expect(fetched().filter(blockscoutOrEtherscan)).toEqual([]);
+        expect(page.hidden("tx-detail-blockscout-note")).toBe(false);
+        cleanupPopup();
+
+        const on = await bootPopup(
+            onTransactionScreen({ useBlockscout: true }),
+        );
+        expect(fetched().filter(blockscoutOrEtherscan)).toEqual([
+            BLOCKSCOUT + "/transactions/" + TX_HASH,
+        ]);
+        expect(on.hidden("tx-detail-blockscout-note")).toBe(true);
+    });
+
+    // Another page turns "Use Blockscout" off while TransactionDetail's request
+    // to Blockscout is out. This page draws TransactionDetail again with its
+    // line, and only then does Blockscout answer.
+    test("TransactionDetail shows nothing from an answer that lands after another page turned Use Blockscout off", async () => {
+        const page = await bootPopup(
+            onTransactionScreen({ useBlockscout: true }),
+        );
+        let release;
+        const held = new Promise((resolve) => {
+            release = resolve;
+        });
+        globalThis.fetch = jest.fn(async () => {
+            await held;
+            return {
+                ok: true,
+                status: 200,
+                json: async () => ({
+                    block_number: 21000000,
+                    fee: { value: "21000000000000" },
+                    raw_input: "0x12345678",
+                    method: "doSomething",
+                }),
+            };
+        });
+        require("../src/popup/views/transactionDetail").render();
+        await page.settle();
+        expect(fetched()).toEqual([BLOCKSCOUT + "/transactions/" + TX_HASH]);
+
+        await anotherPageAnnounces(page, { useBlockscout: false });
+        release();
+        await page.settle();
+
+        expect(page.visibleViews()).toEqual(["transaction"]);
+        expect(page.hidden("tx-detail-blockscout-note")).toBe(false);
+        for (const id of [
+            "tx-detail-block-section",
+            "tx-detail-network-section",
+            "tx-detail-calldata-section",
+            "tx-detail-rawdata-section",
+        ]) {
+            expect(page.hidden(id)).toBe(true);
+        }
+        expect(fetched()).toHaveLength(1);
+    });
+
+    // The confirmation screen for a send of 0.1 ETH to RECIPIENT, as a
+    // reopened popup draws it.
+    function onConfirmScreen(extra) {
+        return unversionedValidProfile({
+            currentView: "confirm-tx",
+            viewStack: ["main"],
+            selectedWallet: 0,
+            selectedAddress: 0,
+            viewData: {
+                pendingTx: {
+                    token: "ETH",
+                    from: ADDRESS,
+                    to: RECIPIENT,
+                    amount: "0.1",
+                    chainId: "0x1",
+                },
+            },
+            ...extra,
+        });
+    }
+
+    test("ConfirmTx asks Etherscan about the recipient only while Check recipients on Etherscan is on", async () => {
+        const page = await bootPopup(onConfirmScreen());
+        expect(page.visibleViews()).toEqual(["confirm-tx"]);
+        expect(fetched().filter(blockscoutOrEtherscan)).toEqual([]);
+        expect(page.hidden("confirm-etherscan-note")).toBe(false);
+        expect(page.hidden("confirm-etherscan-warning")).toBe(true);
+        cleanupPopup();
+
+        const on = await bootPopup(
+            onConfirmScreen({ checkRecipientsOnEtherscan: true }),
+        );
+        expect(fetched().filter(blockscoutOrEtherscan)).toEqual([
+            "https://etherscan.io/address/" + RECIPIENT,
+        ]);
+        expect(on.hidden("confirm-etherscan-note")).toBe(true);
+        expect(on.hidden("confirm-etherscan-warning")).toBe(false);
+    });
+
+    // Ticks or unticks a checkbox on the page, as the user does.
+    async function setBox(page, id, checked) {
+        const box = page.node(id);
+        box.checked = checked;
+        for (const fn of box.listeners.change) await fn();
+        await page.settle();
+    }
+
+    test("Welcome offers both settings unticked, and ticking one there stores it", async () => {
+        const page = await bootPopup(undefined);
+        expect(page.visibleViews()).toEqual(["welcome"]);
+        expect(page.node("welcome-use-blockscout").checked).toBe(false);
+        expect(page.node("welcome-check-recipients-on-etherscan").checked).toBe(
+            false,
+        );
+
+        await setBox(page, "welcome-use-blockscout", true);
+        expect(page.storage.read("autistmask").useBlockscout).toBe(true);
+        await setBox(page, "welcome-check-recipients-on-etherscan", true);
+        expect(page.storage.read("autistmask").checkRecipientsOnEtherscan).toBe(
+            true,
+        );
+    });
+
+    test("Settings shows both settings unticked, and ticking one there stores it", async () => {
+        const page = await bootPopup(unversionedValidProfile());
+        await page.click("btn-settings");
+        expect(page.node("settings-use-blockscout").checked).toBe(false);
+        expect(
+            page.node("settings-check-recipients-on-etherscan").checked,
+        ).toBe(false);
+
+        await setBox(page, "settings-use-blockscout", true);
+        expect(page.storage.read("autistmask").useBlockscout).toBe(true);
+        await setBox(page, "settings-check-recipients-on-etherscan", true);
+        expect(page.storage.read("autistmask").checkRecipientsOnEtherscan).toBe(
+            true,
+        );
+    });
+
+    // A token the user tracks, and an untracked one that Blockscout reported.
+    // Both are written in lower case, because the balance rows' and the
+    // dropdown's token ids are compared in lower case below.
+    const TRACKED = "0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb";
+    const UNTRACKED = TOKEN_ADDRESS.toLowerCase();
+    const SECOND_ADDRESS = "0x3333333333333333333333333333333333333333";
+
+    function tokenRow(address, symbol) {
+        return {
+            address,
+            name: symbol,
+            symbol,
+            decimals: 18,
+            balance: "5.0",
+            holders: 50000,
+        };
+    }
+
+    // AddressDetail of the first of two addresses, as a reopened popup draws
+    // it. Both addresses hold the tracked token. While "Use Blockscout" is on,
+    // both hold the untracked one too.
+    function onAddressDetail(useBlockscout) {
+        const profile = unversionedValidProfile({
+            useBlockscout,
+            currentView: "address",
+            viewStack: ["main"],
+            selectedWallet: 0,
+            selectedAddress: 0,
+            trackedTokens: [
+                { address: TRACKED, name: "TRK", symbol: "TRK", decimals: 18 },
+            ],
+        });
+        const wallet = profile.wallets[0];
+        wallet.nextIndex = 2;
+        wallet.addresses.push({ address: SECOND_ADDRESS, balance: "0.0" });
+        for (const addr of wallet.addresses) {
+            addr.tokenBalances = useBlockscout
+                ? [tokenRow(TRACKED, "TRK"), tokenRow(UNTRACKED, "TST")]
+                : [tokenRow(TRACKED, "TRK")];
+        }
+        return profile;
+    }
+
+    // The token ids of the options created after the first `from` elements.
+    // The page stub keeps no children, so this reads the options for Send's
+    // dropdown from the elements the page created.
+    function optionsSince(page, from) {
+        return page.document.created
+            .slice(from)
+            .filter((el) => el.tagName === "OPTION")
+            .map((el) => el.value.toLowerCase());
+    }
+
+    test("unticking Use Blockscout from AddressDetail's gear takes the untracked token off AddressDetail, Send's dropdown and Home on Back", async () => {
+        const page = await bootPopup(onAddressDetail(true));
+        expect(page.visibleViews()).toEqual(["address"]);
+        expect(page.node("address-balances").innerHTML).toContain(UNTRACKED);
+
+        await page.click("btn-settings");
+        await setBox(page, "settings-use-blockscout", false);
+        const from = page.document.created.length;
+        await page.click("btn-settings-back");
+
+        expect(page.visibleViews()).toEqual(["address"]);
+        const balances = page.node("address-balances").innerHTML;
+        expect(balances).toContain(TRACKED);
+        expect(balances).not.toContain(UNTRACKED);
+        expect(page.hidden("address-tokens-note")).toBe(false);
+        expect(optionsSince(page, from)).toEqual([TRACKED]);
+
+        await page.click("btn-send");
+        expect(page.visibleViews()).toEqual(["send"]);
+        expect(page.hidden("send-token-dropdown")).toBe(false);
+        expect(page.hidden("send-tokens-note")).toBe(false);
+
+        await page.click("btn-send-back");
+        await page.click("btn-address-back");
+        expect(page.visibleViews()).toEqual(["main"]);
+        const home = page.node("wallet-list").innerHTML;
+        expect(home).toContain(TRACKED);
+        expect(home).not.toContain(UNTRACKED);
+
+        const stored = page.storage.read("autistmask");
+        for (const addr of stored.wallets[0].addresses) {
+            expect(
+                addr.tokenBalances.map((row) => row.address.toLowerCase()),
+            ).toEqual([TRACKED]);
+        }
+    });
+
+    // Send's dropdown was filled under the old setting, and Back cannot draw
+    // Send again. So Back lands on the screen under it.
+    test.each([
+        ["unticking", true],
+        ["ticking", false],
+    ])(
+        "%s Use Blockscout from Send's gear lands Back on AddressDetail",
+        async (_how, before) => {
+            const page = await bootPopup(onAddressDetail(before));
+            await page.click("btn-send");
+            expect(page.visibleViews()).toEqual(["send"]);
+
+            await page.click("btn-settings");
+            await setBox(page, "settings-use-blockscout", !before);
+            await page.click("btn-settings-back");
+            expect(page.visibleViews()).toEqual(["address"]);
+            expect(page.hidden("address-tokens-note")).toBe(!before);
+        },
+    );
+
+    test("Send says under its token dropdown that only tracked tokens are listed while Use Blockscout is off", async () => {
+        const off = await bootPopup(onAddressDetail(false));
+        await off.click("btn-send");
+        expect(off.hidden("send-token-dropdown")).toBe(false);
+        expect(off.hidden("send-tokens-note")).toBe(false);
+        cleanupPopup();
+
+        const on = await bootPopup(onAddressDetail(true));
+        await on.click("btn-send");
+        expect(on.hidden("send-token-dropdown")).toBe(false);
+        expect(on.hidden("send-tokens-note")).toBe(true);
+    });
+
+    test("Send opened from AddressToken shows neither the dropdown nor its line", async () => {
+        const page = await bootPopup({
+            ...onAddressDetail(false),
+            currentView: "address-token",
+            viewStack: ["main", "address"],
+            selectedToken: "ETH",
+        });
+        expect(page.visibleViews()).toEqual(["address-token"]);
+        await page.click("btn-address-token-send");
+        expect(page.visibleViews()).toEqual(["send"]);
+        expect(page.hidden("send-token-dropdown")).toBe(true);
+        expect(page.hidden("send-token-static")).toBe(false);
+    });
+
+    test("DeleteAddress says only tracked tokens are listed while Use Blockscout is off", async () => {
+        for (const useBlockscout of [false, true]) {
+            const page = await bootPopup(onAddressDetail(useBlockscout));
+            require("../src/popup/views/deleteAddress").show(0, 1);
+            expect(page.visibleViews()).toEqual(["delete-address-confirm"]);
+            expect(page.hidden("delete-address-tokens-note")).toBe(
+                useBlockscout,
+            );
+            cleanupPopup();
+        }
+    });
+
+    // The token ids of the first address's balances in the stored profile.
+    function storedTokens(page) {
+        return page.storage
+            .read("autistmask")
+            .wallets[0].addresses[0].tokenBalances.map((row) =>
+                row.address.toLowerCase(),
+            );
+    }
+
+    // Turning the setting off dropped the untracked token. A refresh that
+    // started while the setting was on still saves its balances when it
+    // returns, but not that token. The same refresh in the background is in
+    // tests/backgroundStateIsolation.test.js.
+    test("a refresh that returns after Use Blockscout was turned off saves its balances without the untracked token", async () => {
+        const page = await bootPopup(onAddressDetail(true));
+        const { refreshBalances: held } = require("../src/shared/balances");
+        let answer;
+        held.mockImplementationOnce(async (wallets) => {
+            await new Promise((resolve) => {
+                answer = resolve;
+            });
+            wallets[0].addresses[0].balance = "7.0";
+            wallets[0].addresses[0].tokenBalances = [
+                tokenRow(TRACKED, "TRK"),
+                tokenRow(UNTRACKED, "TST"),
+            ];
+        });
+        const ticking = page.tick();
+        await page.settle();
+
+        await page.click("btn-settings");
+        await setBox(page, "settings-use-blockscout", false);
+        answer();
+        await ticking;
+
+        expect(
+            page.storage.read("autistmask").wallets[0].addresses[0].balance,
+        ).toBe("7.0");
+        expect(storedTokens(page)).toEqual([TRACKED]);
+        await page.click("btn-settings-back");
+        expect(page.node("address-balances").innerHTML).not.toContain(
+            UNTRACKED,
+        );
+    });
+
+    // Another page saves `change` over the stored profile. The browser is not
+    // made to tell this page, so this page sees the change only by reading the
+    // stored profile.
+    function anotherPageSaves(page, change) {
+        page.storage.write("autistmask", {
+            ...page.storage.read("autistmask"),
+            ...change,
+        });
+    }
+
+    test.each([
+        ["off", true, false],
+        ["on", false, true],
+    ])(
+        "after another page turns Use Blockscout %s, this page takes the change and its next refresh is saved",
+        async (_how, before, after) => {
+            const page = await bootPopup(onAddressDetail(before));
+            // The refresh answers as it does under the stored setting.
+            const { refreshBalances: held } = require("../src/shared/balances");
+            held.mockImplementationOnce(async (wallets) => {
+                const addr = wallets[0].addresses[0];
+                addr.balance = "7.0";
+                addr.tokenBalances = after
+                    ? [tokenRow(TRACKED, "TRK"), tokenRow(UNTRACKED, "TST")]
+                    : [tokenRow(TRACKED, "TRK")];
+            });
+
+            anotherPageSaves(page, { useBlockscout: after });
+            await page.tick();
+
+            expect(
+                page.storage.read("autistmask").wallets[0].addresses[0].balance,
+            ).toBe("7.0");
+            expect(storedTokens(page)).toEqual(
+                after ? [TRACKED, UNTRACKED] : [TRACKED],
+            );
+            expect(page.hidden("address-tokens-note")).toBe(after);
+        },
+    );
+
+    test.each([
+        ["off", true, false],
+        ["on", false, true],
+    ])(
+        "after another page turns Check recipients on Etherscan %s, this page's next Etherscan check follows the stored setting",
+        async (_how, before, after) => {
+            const page = await bootPopup(
+                onConfirmScreen({ checkRecipientsOnEtherscan: before }),
+            );
+            anotherPageSaves(page, { checkRecipientsOnEtherscan: after });
+            const from = fetched().length;
+            require("../src/popup/views/confirmTx").show({
+                token: "ETH",
+                from: ADDRESS,
+                to: RECIPIENT,
+                amount: "0.1",
+                chainId: "0x1",
+            });
+            await page.settle();
+
+            // The page also takes the change and draws ConfirmTx again, which
+            // checks once more. So the test counts each URL once, however often
+            // it was asked for.
+            const asked = new Set(
+                fetched().slice(from).filter(blockscoutOrEtherscan),
+            );
+            expect([...asked]).toEqual(
+                after ? ["https://etherscan.io/address/" + RECIPIENT] : [],
+            );
+        },
+    );
+
+    // Another page's save of the whole profile with `change`, which the
+    // browser announces to this page as it announces any write.
+    async function anotherPageAnnounces(page, change) {
+        await page.storage.local.set({
+            autistmask: { ...page.storage.read("autistmask"), ...change },
+        });
+        await page.settle();
+    }
+
+    test("a page open on AddressDetail draws it again when another page turns Use Blockscout off", async () => {
+        const page = await bootPopup(onAddressDetail(true));
+        expect(page.hidden("address-tokens-note")).toBe(true);
+
+        await anotherPageAnnounces(page, { useBlockscout: false });
+
+        expect(page.visibleViews()).toEqual(["address"]);
+        expect(page.hidden("address-tokens-note")).toBe(false);
+        expect(page.node("address-balances").innerHTML).not.toContain(
+            UNTRACKED,
+        );
+        expect(storedTokens(page)).toEqual([TRACKED]);
+    });
+
+    test("a page open on ConfirmTx draws it again when another page turns Check recipients on Etherscan off", async () => {
+        const page = await bootPopup(
+            onConfirmScreen({ checkRecipientsOnEtherscan: true }),
+        );
+        expect(page.hidden("confirm-etherscan-note")).toBe(true);
+
+        await anotherPageAnnounces(page, { checkRecipientsOnEtherscan: false });
+
+        expect(page.visibleViews()).toEqual(["confirm-tx"]);
+        expect(page.hidden("confirm-etherscan-note")).toBe(false);
+    });
+});

tests/chainSwitchGate.test.js

@@ -446,7 +446,10 @@ describe("switching the network in Settings tells every open tab", () => {
         global.chrome.runtime.sendMessage = (msg) => {
             bg.send(msg, POPUP);
         };
-        await require("../src/shared/state").loadState();
+        const { state, loadState } = require("../src/shared/state");
+        await loadState();
+        // Set by showView(), which is mocked above.
+        state.currentView = "settings";
         require("../src/popup/views/settings").init({
             pageClosed: new AbortController().signal,
         });

tests/coldWorkerChainId.test.js

@@ -73,6 +73,8 @@ function loadColdWorker(networkId, opts) {
     jest.doMock("../src/shared/balances", () => ({
         getProvider: () => ({}),
         refreshBalances: options.refreshBalances || jest.fn(async () => {}),
+        dropUntrackedTokens: jest.requireActual("../src/shared/balances")
+            .dropUntrackedTokens,
     }));
     jest.doMock("../src/shared/phishingDomains", () => ({
         isPhishingDomain: () => false,

tests/confirmTxAmount.test.js

@@ -108,7 +108,10 @@ global.fetch = jest.fn(() => {
 });
 
 const { makeStorageStub } = require("./support/storageStub");
-global.chrome = { storage: makeStorageStub(), runtime: { sendMessage() {} } };
+global.chrome = {
+    storage: makeStorageStub({ autistmask: { useBlockscout: true } }),
+    runtime: { sendMessage() {} },
+};
 
 // A stub DOM: every id resolves to a recording element.
 const elements = new Map();
@@ -243,6 +246,10 @@ async function openSend(token, tokenUnits = null) {
     ];
     state.selectedWallet = 0;
     state.selectedAddress = 0;
+    // Blockscout is asked only while the stored "Use Blockscout" is on. The
+    // screens save this page's copy of "Use Blockscout" over the stored one. So
+    // the page's copy is turned on here too.
+    state.useBlockscout = true;
     await refreshBalances(
         state.wallets,
         "https://rpc.example.invalid",

tests/confirmTxLateResult.test.js

@@ -50,8 +50,14 @@ function explorerPage(title) {
 // The explorer labels no address.
 global.fetch = jest.fn(async () => explorerPage("Etherscan"));
 
+// The Etherscan label check is made, so its box can be shown.
 const { makeStorageStub } = require("./support/storageStub");
-global.chrome = { storage: makeStorageStub(), runtime: { sendMessage() {} } };
+global.chrome = {
+    storage: makeStorageStub({
+        autistmask: { checkRecipientsOnEtherscan: true },
+    }),
+    runtime: { sendMessage() {} },
+};
 
 // A stub DOM: every id resolves to a recording element.
 const elements = new Map();

tests/confirmTxNetworkSwitch.test.js

@@ -142,13 +142,19 @@ jest.mock("../src/popup/views/txStatus", () => ({
 }));
 
 // The Etherscan label check is its only caller here: the explorer pages it
-// asks for are recorded, and nothing is fetched.
+// asks for are recorded, and nothing is fetched. The stored profile has the
+// check turned on.
 global.fetch = jest.fn(() => {
     throw new Error("tests must not perform network requests");
 });
 
 const { makeStorageStub } = require("./support/storageStub");
-global.chrome = { storage: makeStorageStub(), runtime: { sendMessage() {} } };
+global.chrome = {
+    storage: makeStorageStub({
+        autistmask: { checkRecipientsOnEtherscan: true },
+    }),
+    runtime: { sendMessage() {} },
+};
 
 // A stub DOM: every id resolves to a recording element.
 const elements = new Map();

tests/contractCreation.test.js

@@ -297,6 +297,8 @@ describe.each([
         state.selectedWallet = 0;
         state.selectedAddress = 0;
         state.selectedToken = "ETH";
+        // The history is Blockscout's.
+        state.useBlockscout = true;
     });
 
     test("a contract creation's row says so, with no colour dot and no address line", async () => {

tests/e2e/firefox/run.js

@@ -867,6 +867,14 @@ step(
             "the page was not told of the approved switch: " +
                 JSON.stringify(events),
         );
+        // The popup, open all along, shows the new network
+        // (https://git.eeqj.de/sneak/AutistMask/issues/650).
+        await d.switchToWindow(env.popupWindow);
+        await d.waitFor(
+            "the open popup to show the testnet banner",
+            `const banner = document.getElementById("debug-banner");
+             return banner !== null && banner.textContent === "[TESTNET]";`,
+        );
 
         await openNetworkPrompt(env, "switch-restore", sepolia, mainnet);
         await d.click("#btn-approve-network");
@@ -881,6 +889,10 @@ step(
             isDeepStrictEqual(await storedNetwork(env), before),
             "switching back did not restore the mainnet network and endpoints",
         );
+        await d.waitFor(
+            "the open popup to drop the testnet banner",
+            `return document.getElementById("debug-banner") === null;`,
+        );
         await d.switchToWindow(env.dappWindow);
     },
 );
@@ -1023,11 +1035,14 @@ step(
     },
 );
 
+// A closed approval window leaves its request pending, and the toolbar button
+// opens it (https://git.eeqj.de/sneak/AutistMask/issues/673). WebDriver cannot
+// see the toolbar popup, so its page is opened in a tab, at the URL the
+// extension put on the button.
 step(
-    "closing an approval window rejects the request with 4001",
+    "a closed approval window leaves the request pending until it is rejected",
     async (env) => {
         const d = env.driver;
-        const before = env.server.broadcast.length;
 
         await d.switchToWindow(env.dappWindow);
         await startRequest(d, "sign-closed", "personal_sign", [
@@ -1041,15 +1056,45 @@ step(
 
         // Closed, not rejected: this is the windows.onRemoved path, which can
         // only fire if windows.create() handed back a window id for the
-        // approval to be matched against — call site 4 in the issue, and the
-        // reason suppressing that write-back turns this step red.
+        // approval to be matched against. Without that id the toolbar button
+        // never opens the approval, and this step fails.
         await d.closeWindow(env.dappWindow);
-
-        await assertUserRejection(d, "sign-closed", "a closed approval window");
+        const outcome = await settleRequest(d, "sign-closed", 2000);
         assert(
-            env.server.broadcast.length === before,
-            "a closed approval window still put a transaction on the node",
+            outcome.settled === "pending",
+            "closing the approval window answered the page: " +
+                JSON.stringify(outcome),
         );
+
+        await d.switchToWindow(env.popupWindow);
+        const url = await d.executeAsync(
+            `const done = arguments[arguments.length - 1];
+             browser.browserAction.getPopup({}).then(done, (e) => done(String(e)));`,
+        );
+        assert(
+            url.includes("?approval="),
+            "the toolbar button does not open the pending approval: " + url,
+        );
+        const reopened = await d.newWindow("tab");
+        await d.switchToWindow(reopened);
+        await d.navigate(url);
+        await d.waitVisible("#view-approve-sign");
+        await d.click("#btn-reject-sign");
+
+        await d.switchToWindow(env.dappWindow);
+        await assertUserRejection(
+            d,
+            "sign-closed",
+            "the signature request rejected from the toolbar button",
+        );
+
+        // A page may close only a window a script opened, so the tab can
+        // still be open.
+        const left = await d.findWindow((u) => u.includes("?approval="));
+        if (left) {
+            await d.switchToWindow(left);
+            await d.closeWindow(env.dappWindow);
+        }
     },
 );
 

tests/e2e/network.js

@@ -653,6 +653,12 @@ function traceEnabled(raw) {
  *   confirmed receipt instead of null, so a wait screen resolves.
  * @param {boolean} [opts.failReceiptLookup]  answer eth_getTransactionReceipt
  *   with an error, so every receipt lookup fails; read at request time.
+ * @param {string} [opts.etherscanLabel]  the label Etherscan's page gives the
+ *   address asked about, such as "Fake_Phishing1"; none when unset. Read at
+ *   request time.
+ * @param {object[]} [opts.requests]  a list for the requests this handler
+ *   sees. Each is appended in order as { method, url, fromWorker }, whether it
+ *   came from a popup page or the background worker.
  * @returns {Promise<{waitForServiceWorkerTraffic: (ms: number) =>
  *   Promise<string|null>}>}
  */
@@ -691,6 +697,13 @@ async function installNetworkStubs(ctx, opts) {
             const origin = fromWorker ? "[sw] " : "[page] ";
             console.log("# routed " + origin + req.method() + " " + req.url());
         }
+        if (Array.isArray(opts.requests)) {
+            opts.requests.push({
+                method: req.method(),
+                url: req.url(),
+                fromWorker,
+            });
+        }
 
         // JSON-RPC endpoint (any host): a POST with a JSON-RPC body.
         if (req.method() === "POST") {
@@ -762,12 +775,20 @@ async function installNetworkStubs(ctx, opts) {
             return route.fulfill({ status: 204, body: "" });
         }
 
-        // Best-effort Etherscan address labels: served as an empty page.
+        // Best-effort Etherscan address labels: served as an empty page, or
+        // as a page labelling the address with opts.etherscanLabel.
         if (url.hostname.endsWith("etherscan.io")) {
+            const title = opts.etherscanLabel
+                ? "<title>" +
+                  opts.etherscanLabel +
+                  " | Address: " +
+                  p.split("/").pop() +
+                  " | Etherscan</title>"
+                : "";
             return route.fulfill({
                 status: 200,
                 contentType: "text/html",
-                body: "<html><body></body></html>",
+                body: "<html><head>" + title + "</head><body></body></html>",
             });
         }
 

tests/e2e/run.js

@@ -269,6 +269,69 @@ test("the exact confirmation phrase erases the record and reloads into Welcome (
     }
 });
 
+// ------------------ Blockscout and Etherscan are sent no user data (#668)
+//
+// A fresh install sends Blockscout and Etherscan none of the user's data until
+// the user turns on "Use Blockscout" or "Check recipients on Etherscan". One
+// request still reaches Blockscout while "Use Blockscout" is off: pressing
+// "Save" beside the Blockscout URL asks that URL for `/stats`. That request
+// carries no user data.
+//
+// The route handler in tests/e2e/network.js records in env.routeOpts.requests
+// every request the extension makes, from its pages and its background worker.
+// Recording starts when launch() in tests/e2e/harness.js installs that handler,
+// before the first popup page opens. The background worker starts earlier, but
+// it makes no request while it starts up.
+//
+// Before either setting is changed, these tests drive:
+//
+//   - Home, AddressDetail, AddressToken and ConfirmTx
+//   - the background's own balance refresh
+//
+// Then they turn each setting on and watch its requests start. "Use Blockscout"
+// is also turned off once and on again, to see an untracked token leave every
+// list. TransactionDetail, which also asks Blockscout, is left to the unit
+// tests in tests/blockscoutEtherscanSettings.test.js.
+
+// The line shown in place of the three transaction histories while "Use
+// Blockscout" is off. Written out here rather than imported, so the assertion
+// does not compare the popup with itself.
+const HISTORY_OFF =
+    'No transaction history is shown, because "Use Blockscout" is off in Settings.';
+
+// The requests made so far to Blockscout or Etherscan.
+function explorerRequests(env) {
+    return env.routeOpts.requests.filter(({ url }) => {
+        const host = new URL(url).hostname;
+        return host.endsWith("blockscout.com") || host.endsWith("etherscan.io");
+    });
+}
+
+// Waits until the list `listId` shows the line saying "Use Blockscout" is off.
+async function waitForHistoryOff(page, listId) {
+    await page.waitForFunction(
+        ([id, want]) => document.getElementById(id).textContent.trim() === want,
+        [listId, HISTORY_OFF],
+        { timeout: 15000 },
+    );
+}
+
+test("Welcome offers Use Blockscout and Check recipients on Etherscan, both unticked (#668)", async (env) => {
+    await visible(env.page, "#view-welcome");
+    for (const id of [
+        "welcome-use-blockscout",
+        "welcome-check-recipients-on-etherscan",
+    ]) {
+        const st = await controlState(env.page, id);
+        assert(st !== null, "Welcome has no #" + id);
+        assert(
+            st.tag === "input" && st.type === "checkbox",
+            "#" + id + " is a <" + st.tag + " type=" + st.type + ">",
+        );
+        assert(st.checked === false, "#" + id + " is ticked on a new install");
+    }
+});
+
 // The address scan that follows creating the wallet is held, so the popup
 // reloads while it is in flight. As for the reloads mid-refresh further down,
 // the assertion for that is the harness's own: a console.error from the page
@@ -296,6 +359,261 @@ test("wallet creation through the UI reaches the main view, and reloading mid-sc
     assert(addrCount > 0, "no addresses rendered in the wallet list");
 });
 
+test("with neither setting changed, Home, AddressDetail, AddressToken and ConfirmTx say what is off (#668)", async (env) => {
+    // Funded, so Send leads to the confirmation screen.
+    env.routeOpts.ethBalanceWei = toHexWei(FUNDED_ETH_WEI);
+    try {
+        await visible(env.page, "#view-main");
+        await waitForHistoryOff(env.page, "home-tx-list");
+        await visible(env.page, "#home-tokens-note");
+        await env.page.waitForFunction(
+            (want) =>
+                document
+                    .getElementById("wallet-list")
+                    .textContent.includes(want),
+            quantity(FUNDED_ETH_WEI),
+            { timeout: 60000 },
+        );
+
+        await openAddressDetail(env.page);
+        await waitForHistoryOff(env.page, "tx-list");
+        await visible(env.page, "#address-tokens-note");
+
+        await env.page.locator('#address-balances [data-token="ETH"]').click();
+        await visible(env.page, "#view-address-token");
+        await waitForHistoryOff(env.page, "address-token-tx-list");
+        await env.page.click("#btn-address-token-back");
+        await visible(env.page, "#view-address");
+
+        await goToConfirm(env.page, {
+            token: "ETH",
+            balance: FUNDED_ETH_TEXT + " ETH",
+            amount: COMFORTABLE_AMOUNT,
+        });
+        await waitForEstimate(env.page);
+        await visible(env.page, "#confirm-etherscan-note");
+        assert(
+            !(await env.page.isVisible("#confirm-etherscan-warning")),
+            "ConfirmTx keeps the Etherscan warning's place while no Etherscan check is made",
+        );
+        await backToAddress(env.page);
+    } finally {
+        env.routeOpts.ethBalanceWei = null;
+    }
+});
+
+// The background refreshes balances on its alarm, once a minute. It skips a
+// refresh when the stored record says one ran in the last 30 seconds. The open
+// popup's own refresh runs every 10. So the popup is closed first. The test then
+// has the background worker set the stored time of the last refresh to 0, so
+// its next alarm runs a refresh.
+test("with neither setting changed, nothing has reached Blockscout or Etherscan, the background's refresh included (#668)", async (env) => {
+    await waitForPersisted(
+        env.page,
+        "currentView",
+        "address",
+        "before the popup is closed",
+    );
+    await env.page.close();
+    const [worker] = env.ctx.serviceWorkers();
+    await worker.evaluate(
+        () =>
+            new Promise((resolve) => {
+                chrome.storage.local.get("autistmask", (r) => {
+                    const record = r.autistmask;
+                    record.lastBalanceRefresh = 0;
+                    chrome.storage.local.set({ autistmask: record }, resolve);
+                });
+            }),
+    );
+    const before = env.routeOpts.requests.length;
+    const deadline = Date.now() + 75000;
+    while (
+        !env.routeOpts.requests
+            .slice(before)
+            .some((r) => r.fromWorker && r.method === "POST")
+    ) {
+        assert(
+            Date.now() < deadline,
+            "the background's balance refresh never asked the RPC endpoint",
+        );
+        await sleep(250);
+    }
+    // The refresh's RPC reads and any Blockscout request start together.
+    await sleep(3000);
+
+    const seen = explorerRequests(env);
+    assert(
+        seen.length === 0,
+        "a fresh install asked Blockscout or Etherscan: " +
+            JSON.stringify(seen),
+    );
+    // The watch saw the popup's own traffic as well as the worker's.
+    assert(
+        env.routeOpts.requests.some((r) => !r.fromWorker),
+        "no request from the popup was recorded",
+    );
+    // The popup reopens on the address screen the test above left it on.
+    env.page = await openPopup(env.ctx, env.popupUrl);
+    await visible(env.page, "#view-address");
+});
+
+// Ticked from AddressDetail's gear, so Back lands on the screen that said the
+// setting is off.
+test("turning on Use Blockscout from AddressDetail's gear asks Blockscout for that screen's history on Back, then for the tokens (#668)", async (env) => {
+    await openAddressDetail(env.page);
+    await waitForHistoryOff(env.page, "tx-list");
+    await openSettings(env.page);
+    await env.page.check("#settings-use-blockscout");
+    await waitForPersisted(env.page, "useBlockscout", true, "once ticked");
+    const historyAsked = env.page.waitForRequest(
+        (r) =>
+            r.url().includes("blockscout.com") &&
+            r.url().endsWith("/transactions"),
+    );
+    const tokensAsked = env.page.waitForRequest(
+        (r) => r.url().endsWith("/token-balances"),
+        { timeout: 30000 },
+    );
+    await env.page.click("#btn-settings-back");
+    await visible(env.page, "#view-address");
+    await historyAsked;
+    await env.page.waitForFunction(
+        () =>
+            document
+                .getElementById("tx-list")
+                .textContent.includes("No transactions found."),
+        null,
+        { timeout: 15000 },
+    );
+    assert(
+        !(await env.page.isVisible("#address-tokens-note")),
+        "AddressDetail still says only tracked tokens are listed",
+    );
+
+    await goHome(env.page);
+    await tokensAsked;
+    await env.page.waitForFunction(
+        () =>
+            document
+                .getElementById("home-tx-list")
+                .textContent.includes("No transactions found."),
+        null,
+        { timeout: 15000 },
+    );
+    assert(
+        !(await env.page.isVisible("#home-tokens-note")),
+        "Home still says only tracked tokens are listed",
+    );
+});
+
+// Unticked from AddressDetail's gear while the address holds the stub token,
+// which the user has not tracked and only Blockscout reports. Ticked again at
+// the end, so the rest of the run has Blockscout as before.
+test("turning off Use Blockscout from AddressDetail's gear takes an untracked token off AddressDetail, Send and Home on Back (#668)", async (env) => {
+    env.routeOpts.ethBalanceWei = toHexWei(FUNDED_ETH_WEI);
+    env.routeOpts.seedTokenBalance = true;
+    const tokenRow = '[data-token="' + STUB_TOKEN.address + '"]';
+    try {
+        await settleOnMain(env, { ethWei: FUNDED_ETH_WEI, expectToken: true });
+        await openAddressDetail(env.page);
+        await visible(env.page, "#address-balances " + tokenRow);
+
+        await openSettings(env.page);
+        await env.page.uncheck("#settings-use-blockscout");
+        await waitForPersisted(
+            env.page,
+            "useBlockscout",
+            false,
+            "once unticked",
+        );
+        await env.page.click("#btn-settings-back");
+        await visible(env.page, "#view-address");
+        await visible(env.page, "#address-tokens-note");
+        assert(
+            (await env.page
+                .locator("#address-balances " + tokenRow)
+                .count()) === 0,
+            "AddressDetail still lists the untracked token",
+        );
+
+        await env.page.click("#btn-send");
+        await visible(env.page, "#view-send");
+        await visible(env.page, "#send-tokens-note");
+        const offered = await env.page.$$eval("#send-token option", (opts) =>
+            opts.map((opt) => opt.value.toLowerCase()),
+        );
+        assert(
+            !offered.includes(STUB_TOKEN.address),
+            "Send's dropdown still offers the untracked token",
+        );
+        await env.page.click("#btn-send-back");
+        await visible(env.page, "#view-address");
+
+        await goHome(env.page);
+        await visible(env.page, "#home-tokens-note");
+        assert(
+            (await env.page.locator("#wallet-list " + tokenRow).count()) === 0,
+            "Home still lists the untracked token",
+        );
+    } finally {
+        await openSettings(env.page);
+        await env.page.check("#settings-use-blockscout");
+        await waitForPersisted(env.page, "useBlockscout", true, "ticked again");
+        await env.page.click("#btn-settings-back");
+        env.routeOpts.ethBalanceWei = null;
+        env.routeOpts.seedTokenBalance = false;
+    }
+});
+
+// Ticked from ConfirmTx's gear, so Back lands on the screen that said no
+// Etherscan check was made. Left on for the rest of the run, so the later
+// confirmation screens are driven with the check made.
+test("turning on Check recipients on Etherscan from ConfirmTx's gear has ConfirmTx ask Etherscan on Back and show its label (#668)", async (env) => {
+    env.routeOpts.ethBalanceWei = toHexWei(FUNDED_ETH_WEI);
+    env.routeOpts.etherscanLabel = "Fake_Phishing668";
+    try {
+        await settleOnMain(env, { ethWei: FUNDED_ETH_WEI });
+        await goToConfirm(env.page, {
+            token: "ETH",
+            balance: FUNDED_ETH_TEXT + " ETH",
+            amount: COMFORTABLE_AMOUNT,
+        });
+        await visible(env.page, "#confirm-etherscan-note");
+
+        await openSettings(env.page);
+        await env.page.check("#settings-check-recipients-on-etherscan");
+        await waitForPersisted(
+            env.page,
+            "checkRecipientsOnEtherscan",
+            true,
+            "once ticked",
+        );
+        const before = env.routeOpts.requests.length;
+        await env.page.click("#btn-settings-back");
+        await visible(env.page, "#view-confirm-tx");
+        await visible(env.page, "#confirm-etherscan-warning", 30000);
+        assert(
+            !(await env.page.isVisible("#confirm-etherscan-note")),
+            "ConfirmTx says no Etherscan check was made, with the check on",
+        );
+        const asked = env.routeOpts.requests
+            .slice(before)
+            .map((r) => r.url.toLowerCase())
+            .filter((url) => url.includes("etherscan.io"));
+        assert(
+            asked.length === 1 &&
+                asked[0] ===
+                    "https://etherscan.io/address/" + STUB_COUNTERPARTY,
+            "ConfirmTx asked Etherscan for " + JSON.stringify(asked),
+        );
+        await backToAddress(env.page);
+    } finally {
+        env.routeOpts.ethBalanceWei = null;
+        env.routeOpts.etherscanLabel = null;
+    }
+});
+
 test("add token screen opens from address detail (#150)", async (env) => {
     await openAddressDetail(env.page);
     await env.page.click("#btn-add-token");
@@ -3480,6 +3798,24 @@ function hostileSymbolState(page, tokenAddress) {
 }
 
 test("a token whose symbol() returns markup renders as text (#307)", async (env) => {
+    // The stub token is no longer tracked from here on, so the explorer is
+    // what lists it, as it lists a token airdropped to the victim. A tracked
+    // token is listed from the RPC endpoint under the symbol it was added
+    // with, which the hostile symbol below never reaches
+    // (https://git.eeqj.de/sneak/AutistMask/issues/669).
+    await env.page.click("#btn-settings");
+    await visible(env.page, "#view-settings");
+    await env.page.click("#settings-tracked-tokens .btn-remove-token");
+    // The list is drawn again once the removal is saved.
+    await env.page.waitForFunction(
+        () =>
+            document
+                .getElementById("settings-tracked-tokens")
+                .innerText.trim() === "None",
+    );
+    await env.page.click("#btn-settings-back");
+    await visible(env.page, "#view-address");
+
     env.routeOpts.ethBalanceWei = toHexWei(FUNDED_ETH_WEI);
     env.routeOpts.seedTokenBalance = true;
     env.routeOpts.tokenSymbolOverride = HOSTILE_SYMBOL;
@@ -3774,11 +4110,12 @@ async function waitForApprovalWindow(ctx, timeout = 30000) {
 // reservation exists.
 // How long the tab creation above is given to take effect before the request
 // that raises the next prompt is issued. Dismissing a browser-action popup
-// disconnects its port, and src/background/index.js calls resetPopupUrl() on
-// that disconnect; issued too early, the next request's setPopup() is undone
-// by the previous popup's teardown, chrome.action.openPopup() then rejects,
-// and the fallback window it opens dismisses the popup that was just raised —
-// which settles the fresh approval as a rejection before it can be seen.
+// disconnects its port, and src/background/index.js calls
+// updateToolbarPopup() on that disconnect; issued too early, the next
+// request's setPopup() is undone by the previous popup's teardown,
+// chrome.action.openPopup() then rejects, and the fallback window it opens
+// dismisses the popup that was just raised — which settles the fresh approval
+// as a rejection before it can be seen.
 // Every one of those steps was observed. 1.5s is comfortably past it.
 const APPROVAL_TAB_SETTLE_MS = 1500;
 
@@ -3804,6 +4141,17 @@ async function reserveApprovalTab(env) {
     return env.approvalTab;
 }
 
+// The URL the extension has put on the action: the page the toolbar button
+// opens.
+function toolbarPopupUrl(env) {
+    return env.page.evaluate(
+        () =>
+            new Promise((resolve) => {
+                chrome.action.getPopup({}, (u) => resolve(String(u)));
+            }),
+    );
+}
+
 // The site-connection prompt: the window the extension opened if it managed
 // to open one, and the reserved tab at the action's approval URL otherwise.
 async function openSiteApprovalPopup(env, timeout = 30000) {
@@ -3814,12 +4162,7 @@ async function openSiteApprovalPopup(env, timeout = 30000) {
             .find((p) => !p.isClosed() && p.url().includes("?approval="));
         if (existing) return existing;
 
-        const url = await env.page.evaluate(
-            () =>
-                new Promise((resolve) => {
-                    chrome.action.getPopup({}, (u) => resolve(String(u)));
-                }),
-        );
+        const url = await toolbarPopupUrl(env);
         if (url.includes("?approval=")) {
             await env.approvalTab.goto(url);
             return env.approvalTab;
@@ -4691,6 +5034,116 @@ test("eth_sendTransaction rejected broadcasts nothing (#183)", async (env) => {
     );
 });
 
+// A transaction or signature approval stays pending when its window closes.
+// The browser can close that window when the user clicks away from it, for
+// example to copy the password from a password manager. The toolbar button then
+// opens the approval, and the user answers it there
+// (https://git.eeqj.de/sneak/AutistMask/issues/673).
+//
+// This closes the approval window of request `key` and checks that the page
+// has no answer. It then opens the approval again from the toolbar button.
+// Playwright cannot click that button, so its page is opened in a tab, at the
+// URL the extension put on the button.
+async function closeAndReopen(env, key, view) {
+    const approvalWindow = await waitForApprovalWindow(env.ctx);
+    await visible(approvalWindow, view);
+    await approvalWindow.close();
+
+    const outcome = await settleRequest(env.dapp, key, 2000);
+    assert(
+        outcome.settled === "pending",
+        "closing the approval window answered the page: " +
+            JSON.stringify(outcome),
+    );
+
+    const url = await toolbarPopupUrl(env);
+    assert(
+        url.includes("?approval="),
+        "the toolbar button does not open the pending approval: " + url,
+    );
+    const reopened = await env.ctx.newPage();
+    await reopened.goto(url);
+    await visible(reopened, view);
+    return reopened;
+}
+
+// The stub node answers every nonce request with 0, and the wallet refuses a
+// nonce it has already broadcast. A run can therefore approve one dApp
+// transaction only, so here the signature is approved and the transaction
+// rejected.
+test("a closed signature approval is signed from the toolbar button (#673)", async (env) => {
+    await startRequest(env.dapp, "sign-closed", "personal_sign", [
+        SIGN_HEX,
+        env.expectedAddress,
+    ]);
+    const popup = await closeAndReopen(
+        env,
+        "sign-closed",
+        "#view-approve-sign",
+    );
+    let outcome;
+    try {
+        await popup.fill("#approve-sign-password", PASSWORD);
+        await clickAndClose(popup, "#btn-approve-sign");
+        outcome = await settleRequest(env.dapp, "sign-closed");
+    } finally {
+        await closeApprovalPages(env.ctx);
+    }
+    assert(
+        outcome.settled === "resolved",
+        "personal_sign did not resolve: " + JSON.stringify(outcome),
+    );
+    const recovered = getAddress(
+        verifyMessage(getBytes(SIGN_HEX), outcome.result),
+    );
+    assert(
+        recovered === env.expectedAddress,
+        "the personal_sign signature recovers to " +
+            recovered +
+            ", not to the approved address " +
+            env.expectedAddress,
+    );
+
+    const url = await toolbarPopupUrl(env);
+    assert(
+        !url.includes("?approval="),
+        "the toolbar button still opens the answered approval: " + url,
+    );
+});
+
+test("a closed transaction approval is rejected from the toolbar button (#673)", async (env) => {
+    const before = env.routeOpts.broadcastTransactions.length;
+    await startRequest(env.dapp, "tx-closed", "eth_sendTransaction", [
+        {
+            from: env.expectedAddress,
+            to: STUB_COUNTERPARTY,
+            value: toQuantity(TX_VALUE_WEI),
+            data: TX_DATA,
+        },
+    ]);
+    const popup = await closeAndReopen(env, "tx-closed", "#view-approve-tx");
+    try {
+        await clickAndClose(popup, "#btn-reject-tx");
+        await assertUserRejection(
+            env.dapp,
+            "tx-closed",
+            "the transaction rejected from the toolbar button",
+        );
+    } finally {
+        await closeApprovalPages(env.ctx);
+    }
+    assert(
+        env.routeOpts.broadcastTransactions.length === before,
+        "a rejected transaction still reached the RPC",
+    );
+
+    const url = await toolbarPopupUrl(env);
+    assert(
+        !url.includes("?approval="),
+        "the toolbar button still opens the answered approval: " + url,
+    );
+});
+
 // The extension used to centre every approval window on the last focused
 // window. Centred on another approval window, the new one landed where the
 // browser refused to create it, and the request failed with no window at all
@@ -4734,8 +5187,8 @@ test("a prompt raised while another approval window has focus opens its own (#29
     });
     await visible(txWindow, "#view-approve-tx");
 
-    // Closing a window is refusing its prompt, so both answer 4001.
-    await closeApprovalPages(env.ctx);
+    await clickAndClose(txWindow, "#btn-reject-tx");
+    await clickAndClose(signWindow, "#btn-reject-sign");
     await assertUserRejection(env.dapp, "focus-tx", "the transaction prompt");
     await assertUserRejection(env.dapp, "focus-sign", "the sign prompt");
 });
@@ -4865,6 +5318,12 @@ test("a site's network switch changes nothing until the user approves it (#408)"
         "the page was not told of the approved switch: " +
             JSON.stringify(events),
     );
+    // The popup, open all along, shows the new network
+    // (https://git.eeqj.de/sneak/AutistMask/issues/650).
+    await env.page.waitForFunction(() => {
+        const banner = document.getElementById("debug-banner");
+        return banner !== null && banner.textContent === "[TESTNET]";
+    });
 
     const restored = await openNetworkPrompt(
         env,
@@ -4886,6 +5345,9 @@ test("a site's network switch changes nothing until the user approves it (#408)"
         isDeepStrictEqual(await storedNetwork(env.page), before),
         "switching back did not restore the mainnet network and endpoints",
     );
+    await env.page.waitForFunction(
+        () => document.getElementById("debug-banner") === null,
+    );
 });
 
 // Switching the network in Settings tells the page too, as an approved site
@@ -5231,10 +5693,17 @@ async function main() {
         seedReceipt: false,
         // Whether eth_getTransactionReceipt fails instead of answering (#315).
         failReceiptLookup: false,
+        // The label Etherscan's page gives an address, when it gives one
+        // (#668).
+        etherscanLabel: null,
         // Every raw signed transaction handed to eth_sendRawTransaction, in
         // order. The dApp transaction round trip asserts against these bytes
         // rather than against anything the extension reported about them.
         broadcastTransactions: [],
+        // Every request the extension makes, in order, from when launch()
+        // installs the route handler, before the first popup page opens
+        // (#668).
+        requests: [],
     };
 
     let session;
@@ -5326,9 +5795,11 @@ async function main() {
         // for the new one. After a test that passed, its windows get five
         // seconds to close, and one still open then fails the test: it should
         // have closed itself, and closing it here unreported would hide that.
-        // After a test that already failed, they are closed unreported, so
-        // that a prompt it left unanswered does not refuse the next one from
-        // its site.
+        // After a test that already failed, they are closed unreported. That
+        // rejects a site-connection or network-switch prompt it left
+        // unanswered, so the prompt does not refuse the next one from its
+        // site. A transaction or signature approval stays pending, and can
+        // fail the tests after it.
         if (!failure) {
             const deadline = Date.now() + 5000;
             let open;

tests/ensOffchainLookup.test.js

@@ -0,0 +1,114 @@
+// ENS lookups ask nothing but the RPC endpoint. A resolver can answer that a
+// name is resolved off-chain, naming a web address to fetch the answer from.
+// ethers fetches that address unless the provider has `disableCcipRead` set.
+// That request would carry the name to a server other than the RPC endpoint
+// (https://git.eeqj.de/sneak/AutistMask/issues/668). With the flag set, such a
+// name does not resolve.
+//
+// The test builds its provider with getProvider() and runs it against a fake
+// JSON-RPC node. The fake node answers through ethers' own request hook. The
+// hook also records the address of every request ethers makes, the off-chain
+// fetch included.
+
+const { FetchRequest, Interface } = require("ethers");
+const { getProvider } = require("../src/shared/balances");
+
+const RPC_URL = "https://rpc.example.invalid";
+const RESOLVER = "0x5555555555555555555555555555555555555555";
+const USER = "0x1111111111111111111111111111111111111111";
+const NAME = "offchain.eth";
+
+// The ENS registry's resolver(), and the resolver's functions ethers calls:
+//
+//   - the registry names RESOLVER for every name
+//   - the resolver says it resolves names through resolve()
+//   - it gives NAME as the reverse record of any address
+//   - it answers resolve() with the OffchainLookup error, which says the name
+//     is resolved off-chain
+const ens = new Interface([
+    "function resolver(bytes32) view returns (address)",
+    "function supportsInterface(bytes4) view returns (bool)",
+    "function name(bytes32) view returns (string)",
+    "function resolve(bytes, bytes) view returns (bytes)",
+    "error OffchainLookup(address sender, string[] urls, bytes callData, bytes4 callbackFunction, bytes extraData)",
+]);
+
+let asked;
+
+// One JSON-RPC answer. Anything but a call to one of the functions above is
+// refused.
+function reply(req) {
+    const envelope = { jsonrpc: "2.0", id: req.id };
+    const call =
+        req.method === "eth_call" ? ens.parseTransaction(req.params[0]) : null;
+    if (call === null) {
+        return {
+            ...envelope,
+            error: { code: -32601, message: "method not found" },
+        };
+    }
+    if (call.name === "resolve") {
+        const offchain = ens.encodeErrorResult("OffchainLookup", [
+            RESOLVER,
+            ["https://gateway.example.invalid/{sender}/{data}.json"],
+            "0x1234",
+            "0x12345678",
+            "0x",
+        ]);
+        return {
+            ...envelope,
+            error: { code: 3, message: "execution reverted", data: offchain },
+        };
+    }
+    const answers = {
+        resolver: [RESOLVER],
+        supportsInterface: [true],
+        name: [NAME],
+    };
+    return {
+        ...envelope,
+        result: ens.encodeFunctionResult(call.name, answers[call.name]),
+    };
+}
+
+beforeEach(() => {
+    asked = [];
+    FetchRequest.registerGetUrl(async (req) => {
+        asked.push(req.url);
+        // Any other address is the off-chain fetch, answered as not found.
+        if (req.url !== RPC_URL) {
+            return {
+                statusCode: 404,
+                statusMessage: "Not Found",
+                headers: {},
+                body: null,
+            };
+        }
+        const body = JSON.parse(Buffer.from(req.body).toString("utf8"));
+        const answer = Array.isArray(body) ? body.map(reply) : reply(body);
+        return {
+            statusCode: 200,
+            statusMessage: "OK",
+            headers: { "content-type": "application/json" },
+            body: Buffer.from(JSON.stringify(answer)),
+        };
+    });
+});
+
+afterEach(() => {
+    FetchRequest.registerGetUrl(FetchRequest.createGetUrlFunc());
+});
+
+test("a name typed into Send that is resolved off-chain does not resolve, and only the RPC endpoint is asked", async () => {
+    const provider = getProvider(RPC_URL, "mainnet");
+    const [outcome] = await Promise.allSettled([provider.resolveName(NAME)]);
+    expect(asked.filter((url) => url !== RPC_URL)).toEqual([]);
+    expect(outcome).toEqual({ status: "fulfilled", value: null });
+});
+
+test("the reverse lookup of a user's address whose name is resolved off-chain finds no name, and only the RPC endpoint is asked", async () => {
+    const provider = getProvider(RPC_URL, "mainnet");
+    const [outcome] = await Promise.allSettled([provider.lookupAddress(USER)]);
+    expect(asked.filter((url) => url !== RPC_URL)).toEqual([]);
+    expect(outcome).toEqual({ status: "fulfilled", value: null });
+});

tests/fabricatedDecimals.test.js

@@ -35,8 +35,11 @@ global.fetch = jest.fn(() => {
     throw new Error("tests must not perform network requests");
 });
 
+// Blockscout is asked only while the stored "Use Blockscout" is on.
 const { makeStorageStub } = require("./support/storageStub");
-global.chrome = { storage: makeStorageStub() };
+global.chrome = {
+    storage: makeStorageStub({ autistmask: { useBlockscout: true } }),
+};
 
 const { AbiCoder, Interface } = require("ethers");
 const { ERC20_ABI } = require("../src/shared/constants");
@@ -165,6 +168,9 @@ beforeEach(() => {
     debugFetch.mockReset();
     state.trackedTokens = [];
     state.wallets = [];
+    // The approval screens read the explorer's report only while the page's
+    // "Use Blockscout" is on.
+    state.useBlockscout = true;
 });
 
 describe("what fetchTokenBalances stores for an absent scale", () => {

tests/holders.test.js

@@ -21,7 +21,11 @@ jest.mock("../src/shared/log", () => ({
 global.fetch = jest.fn(() => {
     throw new Error("tests must not perform network requests");
 });
-global.chrome = { storage: { local: {} } };
+// Blockscout is asked only while the stored "Use Blockscout" is on.
+const { makeStorageStub } = require("./support/storageStub");
+global.chrome = {
+    storage: makeStorageStub({ autistmask: { useBlockscout: true } }),
+};
 
 const {
     LOW_HOLDER_THRESHOLD,

tests/manifest.test.js

@@ -165,6 +165,15 @@ describe("declared icons", () => {
     });
 });
 
+// Firefox gives a page in a private window locks of its own, so that page's
+// save could land between the background's read and its write (README,
+// "Stored state and its version").
+describe("private windows", () => {
+    test("a page in a firefox private window cannot read or write extension storage", () => {
+        expect(readManifest("firefox").incognito).toBe("not_allowed");
+    });
+});
+
 describe("shipped Content Security Policy", () => {
     // MV3 takes an object and applies extension_pages to the popup and the
     // background service worker, which is where libsodium runs.

tests/nativeCurrency.test.js

@@ -436,6 +436,13 @@ describe.each([
         });
 
         test("the transaction detail screen's type line and fee", async () => {
+            // The fee is Blockscout's, asked for only while the stored "Use
+            // Blockscout" is on.
+            state.useBlockscout = true;
+            global.chrome.storage.write("autistmask", {
+                ...global.chrome.storage.read("autistmask"),
+                useBlockscout: true,
+            });
             debugFetch.mockImplementationOnce(async () => ({
                 ok: true,
                 status: 200,

tests/persistedEntryFloors.test.js

@@ -286,8 +286,12 @@ describe("a malformed fraudContracts", () => {
     function stubSendDocument() {
         const select = { innerHTML: "", children: [] };
         select.appendChild = (child) => select.children.push(child);
+        const elements = {
+            "send-token": select,
+            "send-tokens-note": { classList: { toggle: () => {} } },
+        };
         globalThis.document = {
-            getElementById: (id) => (id === "send-token" ? select : null),
+            getElementById: (id) => elements[id] || null,
             createElement: () => ({ value: "", textContent: "" }),
         };
         return select;

tests/persistedFieldContract.test.js

@@ -629,6 +629,21 @@ const CONTRACT = [
         // the falsy answer is also the DEFAULT_STATE default.
         falsy: [0],
     })),
+    // Anything but true is off for these three settings:
+    // - useBlockscout and checkRecipientsOnEtherscan let a request reach
+    //   another service.
+    // - allowWeakPasswords lets AddWallet accept a short password.
+    ...[
+        "useBlockscout",
+        "checkRecipientsOnEtherscan",
+        "allowWeakPasswords",
+    ].map((field) => ({
+        field,
+        kind: KIND.SCALAR,
+        hostile: [42, "notabool", { a: 1 }],
+        floorOnly: [0, null, "true"],
+        holds: (v) => v === false,
+    })),
 ];
 
 function siteMapHolds(v) {

tests/popupBoot.test.js

@@ -44,7 +44,9 @@ test("a flash message's timer does not fire after cleanupPopup()", async () => {
 
 // A boot onto a screen that sends a request no mocked module answers: that
 // request reaches the boot's fetch() stub, never the internet
-// (https://git.eeqj.de/sneak/AutistMask/issues/559).
+// (https://git.eeqj.de/sneak/AutistMask/issues/559). TransactionDetail asks
+// Blockscout only while "Use Blockscout" is on. ConfirmTx asks Etherscan only
+// while "Check recipients on Etherscan" is on. So the profile turns both on.
 function restoringOnto(view, viewData) {
     return unversionedValidProfile({
         currentView: view,
@@ -52,6 +54,8 @@ function restoringOnto(view, viewData) {
         selectedAddress: 0,
         viewStack: ["main"],
         viewData,
+        useBlockscout: true,
+        checkRecipientsOnEtherscan: true,
     });
 }
 

tests/popupFollowsNetworkSwitch.test.js

@@ -0,0 +1,300 @@
+// An open popup follows a network switch the background saves once the user
+// approves a site's request: it takes the new network from the stored record
+// and draws the screen it is on for it, as a switch in Settings does
+// (https://git.eeqj.de/sneak/AutistMask/issues/650). Driven through the real
+// popup over a stored profile on Ethereum Mainnet. The background's write is
+// the storage stub's set, which the stub reports to the page as the browser
+// does.
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+    TOKEN_ADDRESS,
+} = require("./support/popupBoot");
+const { makeStorageStub } = require("./support/storageStub");
+const {
+    applyChainSwitchFields,
+    copyChainSwitchFields,
+} = require("../src/shared/chainSwitchFields");
+const { NETWORKS } = require("../src/shared/networks");
+const { STATE_SCHEMA_VERSION } = require("../src/shared/stateSchema");
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+const SEPOLIA_TOKEN = {
+    address: TOKEN_ADDRESS,
+    symbol: "TST",
+    decimals: 18,
+    name: "Test Token",
+};
+const MAINNET_TOKEN = {
+    address: "0x6B175474E89094C44Da98b954EedeAC495271d0F",
+    symbol: "DAI",
+    decimals: 18,
+    name: "Dai Stablecoin",
+};
+
+// A profile on Ethereum Mainnet that reopens the popup onto AddressDetail,
+// with DAI tracked there and TST tracked on Sepolia.
+function profileOnAddress() {
+    return unversionedValidProfile({
+        currentView: "address",
+        viewStack: ["main"],
+        selectedWallet: 0,
+        selectedAddress: 0,
+        trackedTokens: [MAINNET_TOKEN],
+        networkTrackedTokens: { sepolia: [SEPOLIA_TOKEN] },
+    });
+}
+
+// The popup reopened onto it.
+function bootOnAddress() {
+    return bootPopup(profileOnAddress());
+}
+
+// The background saves a switch to `networkId`, as its updateState() does
+// once the user approves a site's request.
+async function backgroundSwitch(page, networkId) {
+    const record = page.storage.read("autistmask");
+    applyChainSwitchFields(record, networkId);
+    await page.storage.local.set({ autistmask: record });
+    await page.settle();
+    await page.settle();
+}
+
+test("the popup open on AddressDetail shows the new network and its balances", async () => {
+    const page = await bootOnAddress();
+    expect(page.pageErrors).toEqual([]);
+    expect(page.visibleViews()).toEqual(["address"]);
+    expect(page.node("address-balances").innerHTML).toContain("DAI");
+    expect(page.node("debug-banner")).toBeNull();
+
+    await backgroundSwitch(page, "sepolia");
+
+    const { state } = require("../src/shared/state");
+    expect(state.networkId).toBe("sepolia");
+    expect(state.rpcUrl).toBe(NETWORKS.sepolia.defaultRpcUrl);
+    expect(page.visibleViews()).toEqual(["address"]);
+    const balances = page.node("address-balances").innerHTML;
+    expect(balances).toContain("TST");
+    expect(balances).toContain("SepoliaETH");
+    expect(balances).not.toContain("DAI");
+    expect(page.text("debug-banner")).toBe("[TESTNET]");
+
+    // Its next refresh runs on Sepolia, and what it fetched is stored.
+    await page.tick();
+    const { refreshBalances } = require("../src/shared/balances");
+    expect(refreshBalances.mock.lastCall[4]).toBe("sepolia");
+    const stored = page.storage.read("autistmask");
+    expect(stored.networkId).toBe("sepolia");
+    expect(stored.lastBalanceRefresh).toBeGreaterThan(0);
+});
+
+test("the popup open on Settings shows the new network, and Back draws the screen beneath for it", async () => {
+    const page = await bootOnAddress();
+    await page.click("btn-settings");
+    expect(page.visibleViews()).toEqual(["settings"]);
+
+    await backgroundSwitch(page, "sepolia");
+
+    expect(page.visibleViews()).toEqual(["settings"]);
+    expect(page.value("settings-network")).toBe("sepolia");
+    expect(page.value("settings-rpc")).toBe(NETWORKS.sepolia.defaultRpcUrl);
+    expect(page.node("settings-tracked-tokens").innerHTML).toContain("TST");
+    expect(page.text("debug-banner")).toBe("[TESTNET]");
+
+    await page.click("btn-settings-back");
+    expect(page.visibleViews()).toEqual(["address"]);
+    expect(page.node("address-balances").innerHTML).not.toContain("DAI");
+});
+
+// Neither can be drawn again for the new network: Send cannot be rendered from
+// saved state, and DAI was picked on Ethereum Mainnet, where alone it is
+// tracked. A reopened popup goes to Home in their place.
+test.each([
+    ["Send", (page) => page.click("btn-send")],
+    [
+        "AddressToken for DAI",
+        async (page) => {
+            const { state } = require("../src/shared/state");
+            state.selectedToken = MAINNET_TOKEN.address;
+            require("../src/popup/views/helpers").pushCurrentView();
+            require("../src/popup/views/addressToken").show();
+            await page.settle();
+        },
+    ],
+])("the popup open on %s goes to Home", async (_view, open) => {
+    const page = await bootOnAddress();
+    await open(page);
+    expect(page.visibleViews()).not.toEqual(["address"]);
+
+    await backgroundSwitch(page, "sepolia");
+
+    expect(page.visibleViews()).toEqual(["main"]);
+    expect(page.text("total-value")).toBe("0.0000 SepoliaETH");
+});
+
+// The report of the switch's own save names the network the page already has.
+test("a switch in Settings is not taken a second time when its save is reported", async () => {
+    const page = await bootOnAddress();
+    await page.click("btn-settings");
+    const { get, set } = page.storage.local;
+    const reads = get.mock.calls.length;
+    const writes = set.mock.calls.length;
+
+    const select = page.node("settings-network");
+    select.value = "sepolia";
+    for (const fn of select.listeners.change) await fn();
+    await page.settle();
+    await page.settle();
+
+    expect(get).toHaveBeenCalledTimes(reads + 1);
+    expect(set).toHaveBeenCalledTimes(writes + 1);
+    expect(page.text("flash-msg")).toBe("Switched to Sepolia Testnet.");
+});
+
+// The background saves the switch once the popup has read the stored record
+// and before it listens for changes to it, so the browser tells the page
+// nothing of it. Nor is any later write reported here: Chrome reports none
+// that leaves the record as it was, such as the popup's own save at start-up.
+test("a switch saved while the popup opens, before it listens for one, is followed", async () => {
+    const storage = makeStorageStub({ autistmask: profileOnAddress() });
+    storage.onChanged = { addListener: () => {} };
+    const read = storage.local.get.getMockImplementation();
+    storage.local.get.mockImplementationOnce(async (key) => {
+        const loaded = await read(key);
+        const record = storage.read("autistmask");
+        applyChainSwitchFields(record, "sepolia");
+        storage.write("autistmask", record);
+        return loaded;
+    });
+    const page = await bootPopup(undefined, { storage });
+    await page.settle();
+
+    const { state } = require("../src/shared/state");
+    expect(page.pageErrors).toEqual([]);
+    expect(state.networkId).toBe("sepolia");
+    expect(page.visibleViews()).toEqual(["address"]);
+    expect(page.node("address-balances").innerHTML).toContain("SepoliaETH");
+    expect(page.text("debug-banner")).toBe("[TESTNET]");
+});
+
+// While the popup's follow of the background's switch to Sepolia waits for the
+// lock, the user picks Sepolia in Settings and then Ethereum Mainnet again. The
+// last pick is the network stored, and the last one sites are told of.
+test("a switch in Settings made while a follow waits for the lock is not overwritten by it", async () => {
+    const page = await bootOnAddress();
+    await page.click("btn-settings");
+
+    // Another write holds the lock, so every save of the page waits for it.
+    let releaseLock;
+    const lockHeld = navigator.locks.request(
+        "autistmask",
+        () =>
+            new Promise((resolve) => {
+                releaseLock = resolve;
+            }),
+    );
+    await backgroundSwitch(page, "sepolia");
+    const select = page.node("settings-network");
+    const picks = [];
+    for (const networkId of ["sepolia", "mainnet"]) {
+        select.value = networkId;
+        for (const fn of select.listeners.change) picks.push(fn());
+    }
+    releaseLock();
+    await lockHeld;
+    await Promise.all(picks);
+    await page.settle();
+
+    const { state } = require("../src/shared/state");
+    expect(state.networkId).toBe("mainnet");
+    expect(page.storage.read("autistmask").networkId).toBe("mainnet");
+    expect(page.value("settings-network")).toBe("mainnet");
+    const told = globalThis.chrome.runtime.sendMessage.mock.calls
+        .map(([message]) => message)
+        .filter((message) => message.type === "AUTISTMASK_NETWORK_CHANGED");
+    expect(told.at(-1).chainId).toBe(NETWORKS.mainnet.chainId);
+});
+
+// The popup follows the background's switch to Sepolia, but its own write in
+// that save fails. The user then picks Ethereum Mainnet in Settings, the
+// network the popup was on before: that switch is stored, and only then
+// flashed and sent to sites.
+test("a switch back in Settings after a follow whose write failed is stored", async () => {
+    const page = await bootOnAddress();
+    await page.click("btn-settings");
+    const { set } = page.storage.local;
+    const write = set.getMockImplementation();
+    // The background's write lands; the next, the follow's, fails.
+    set.mockImplementationOnce(write).mockRejectedValueOnce(
+        new Error("quota exceeded"),
+    );
+    await backgroundSwitch(page, "sepolia");
+    const { state } = require("../src/shared/state");
+    expect(state.networkId).toBe("sepolia");
+
+    const select = page.node("settings-network");
+    select.value = "mainnet";
+    for (const fn of select.listeners.change) await fn();
+    await page.settle();
+
+    const stored = page.storage.read("autistmask");
+    expect(stored.networkId).toBe("mainnet");
+    expect(stored.rpcUrl).toBe(NETWORKS.mainnet.defaultRpcUrl);
+    expect(stored.trackedTokens).toEqual([MAINNET_TOKEN]);
+    expect(page.text("flash-msg")).toBe("Switched to Ethereum Mainnet.");
+    const told = globalThis.chrome.runtime.sendMessage.mock.calls
+        .map(([message]) => message)
+        .filter((message) => message.type === "AUTISTMASK_NETWORK_CHANGED");
+    expect(told.at(-1).chainId).toBe(NETWORKS.mainnet.chainId);
+});
+
+// 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.
+test("a record that names no network is not followed", async () => {
+    const page = await bootOnAddress();
+    const { get, set } = page.storage.local;
+    const reads = get.mock.calls.length;
+
+    await set({
+        autistmask: {
+            schemaVersion: STATE_SCHEMA_VERSION + 1,
+            wallets: [{ type: "hd", name: "Main", addresses: [] }],
+        },
+    });
+    await page.settle();
+
+    expect(get).toHaveBeenCalledTimes(reads);
+    expect(page.visibleViews()).toEqual(["address"]);
+});
+
+// A record that takes the switch from the switched record ends up as that
+// record, balances the background fetched since included.
+test("copyChainSwitchFields() takes every field applyChainSwitchFields() sets", () => {
+    const before = unversionedValidProfile({
+        trackedTokens: [MAINNET_TOKEN],
+        networkTrackedTokens: { sepolia: [SEPOLIA_TOKEN] },
+        networkEndpoints: {
+            sepolia: {
+                rpcUrl: "http://127.0.0.1:8545",
+                blockscoutUrl: "http://127.0.0.1:4000/api/v2",
+            },
+        },
+        lastBalanceRefresh: 1,
+        tokenHolderCache: { [MAINNET_TOKEN.address]: 5000 },
+        fraudContracts: ["0x1111111111111111111111111111111111111111"],
+    });
+    const switched = structuredClone(before);
+    applyChainSwitchFields(switched, "sepolia");
+    switched.wallets[0].addresses[0].balance = "2.0";
+
+    const follower = structuredClone(before);
+    copyChainSwitchFields(follower, switched);
+
+    expect(follower).toEqual(switched);
+});

tests/sendDisplayFloor.test.js

@@ -90,7 +90,7 @@ let approvalDetails = null;
 
 const { makeStorageStub } = require("./support/storageStub");
 global.chrome = {
-    storage: makeStorageStub(),
+    storage: makeStorageStub({ autistmask: { useBlockscout: true } }),
     runtime: {
         connect: () => ({
             postMessage() {},
@@ -220,6 +220,10 @@ async function refreshWith(balanceWei, tokenItems = []) {
     state.wallets = [{ name: "Wallet 1", addresses: [{ address: HOLDER }] }];
     state.selectedWallet = 0;
     state.selectedAddress = 0;
+    // Blockscout is asked only while the stored "Use Blockscout" is on. The
+    // screens save this page's copy of "Use Blockscout" over the stored one. So
+    // the page's copy is turned on here too.
+    state.useBlockscout = true;
     await refreshBalances(
         state.wallets,
         "https://rpc.example.invalid",

tests/sendMax.test.js

@@ -100,7 +100,10 @@ global.fetch = jest.fn(() => {
 });
 
 const { makeStorageStub } = require("./support/storageStub");
-global.chrome = { storage: makeStorageStub(), runtime: { sendMessage() {} } };
+global.chrome = {
+    storage: makeStorageStub({ autistmask: { useBlockscout: true } }),
+    runtime: { sendMessage() {} },
+};
 
 // A stub DOM: every id resolves to a recording element.
 const elements = new Map();
@@ -213,6 +216,10 @@ async function refreshWith(balanceWei, tokenItems = []) {
     ];
     state.selectedWallet = 0;
     state.selectedAddress = 0;
+    // Blockscout is asked only while the stored "Use Blockscout" is on. The
+    // screens save this page's copy of "Use Blockscout" over the stored one. So
+    // the page's copy is turned on here too.
+    state.useBlockscout = true;
     await refreshBalances(
         state.wallets,
         "https://rpc.example.invalid",

tests/sendTokenSelect.test.js

@@ -27,8 +27,12 @@ let select;
 function installStubDocument() {
     select = { innerHTML: "", children: [] };
     select.appendChild = (child) => select.children.push(child);
+    const elements = {
+        "send-token": select,
+        "send-tokens-note": { classList: { toggle: () => {} } },
+    };
     globalThis.document = {
-        getElementById: (id) => (id === "send-token" ? select : null),
+        getElementById: (id) => elements[id] || null,
         createElement: () => ({ value: "", textContent: "" }),
     };
 }

tests/stateRecovery.test.js

@@ -523,13 +523,16 @@ describe("a garbage value in a field the gate does not check", () => {
     });
 
     test("a malformed tokenBalances entry is dropped, and the wallet and its address survive", async () => {
-        const env = await bootPopup(
-            profileWithTokenBalances([
-                null,
-                42,
-                { address: TOKEN_ADDRESS, symbol: "AAA", balance: "2.0" },
-            ]),
-        );
+        // "Use Blockscout" is on. Otherwise the boot's balance refresh would
+        // drop the well-formed entry too, since the user has not tracked its
+        // token.
+        const profile = profileWithTokenBalances([
+            null,
+            42,
+            { address: TOKEN_ADDRESS, symbol: "AAA", balance: "2.0" },
+        ]);
+        profile.useBlockscout = true;
+        const env = await bootPopup(profile);
 
         const stored = env.storage.read("autistmask");
         expect(stored.wallets[0].encryptedSecret).toBe("encrypted-secret-1");

tests/stateWriteLock.test.js

@@ -6,9 +6,8 @@
 // now holds a lock from its read to its write.
 //
 // The popup and the background run here as the real modules over one shared
-// storage stub, and share the lock the way the background and a page outside
-// a Firefox private window share the browser's
-// (tests/support/navigatorLocks.js).
+// storage stub, and share the lock the way the background and its pages share
+// the browser's (tests/support/navigatorLocks.js).
 
 const { makeStorageStub } = require("./support/storageStub");
 

tests/support/navigatorLocks.js

@@ -4,9 +4,8 @@
 // the callback settles, whether it resolved or rejected. That is what the
 // browser's own does for the one call the extension makes,
 // `navigator.locks.request(name, callback)`. Every module a test file loads
-// shares it, as the extension's background and its pages share the browser's,
-// except a page in a Firefox private window (README, "Stored state and its
-// version").
+// shares it, as the extension's background and its pages share the browser's
+// (README, "Stored state and its version").
 //
 // Run before each test file by `setupFiles` in package.json.
 

tests/support/popupBoot.js

@@ -283,6 +283,8 @@ async function bootPopup(stored, options) {
     jest.doMock("../../src/shared/balances", () => ({
         fetchTokenBalances: jest.fn(async () => []),
         refreshBalances: jest.fn(async () => {}),
+        dropUntrackedTokens: jest.requireActual("../../src/shared/balances")
+            .dropUntrackedTokens,
         lookupTokenInfo: jest.fn(async () => null),
         getProvider: () => ({}),
         scanForAddresses: jest.fn(async () => ({
@@ -311,7 +313,7 @@ async function bootPopup(stored, options) {
     const windowListeners = {};
 
     globalThis.chrome = {
-        storage: { local: storage.local },
+        storage: { local: storage.local, onChanged: storage.onChanged },
         runtime: {
             sendMessage: jest.fn(async () => ({})),
             getURL: (p) => "chrome-extension://autistmask/" + p,

tests/support/storageStub.js

@@ -18,7 +18,9 @@
 // a storage stub by hand.
 
 // One storage area: get, set and remove over its own store, cloning both ways.
-function makeArea(store, tick) {
+// `changed` is handed what each set or remove changed, in the shape
+// storage.onChanged reports it.
+function makeArea(store, tick, changed) {
     const get = jest.fn(async (key) => {
         tick();
         if (key === undefined || key === null) return structuredClone(store);
@@ -34,14 +36,25 @@ function makeArea(store, tick) {
 
     const set = jest.fn(async (items) => {
         tick();
+        const changes = {};
         for (const k of Object.keys(items)) {
+            changes[k] = structuredClone({
+                oldValue: store[k],
+                newValue: items[k],
+            });
             store[k] = structuredClone(items[k]);
         }
+        changed(changes);
     });
 
     const remove = jest.fn(async (key) => {
         tick();
-        for (const k of Array.isArray(key) ? key : [key]) delete store[k];
+        const changes = {};
+        for (const k of Array.isArray(key) ? key : [key]) {
+            changes[k] = { oldValue: store[k] };
+            delete store[k];
+        }
+        changed(changes);
     });
 
     return { get, set, remove };
@@ -54,12 +67,22 @@ function makeArea(store, tick) {
 function makeStorageStub(initial, onOp) {
     const store = initial ? structuredClone(initial) : {};
     const tick = onOp || (() => {});
-    const local = makeArea(store, tick);
+    // storage.onChanged: after a set or remove has finished, every listener is
+    // called with what it changed and the area's name, as the browser calls
+    // them for a write by any page or the background.
+    const listeners = [];
+    const announce = (areaName) => (changes) => {
+        Promise.resolve().then(() => {
+            for (const fn of listeners) fn(structuredClone(changes), areaName);
+        });
+    };
+    const local = makeArea(store, tick, announce("local"));
 
     return {
         // Drop this straight in as chrome.storage.
         local,
-        session: makeArea({}, tick),
+        session: makeArea({}, tick, announce("session")),
+        onChanged: { addListener: (fn) => listeners.push(fn) },
         get: local.get,
         set: local.set,
         remove: local.remove,
@@ -71,7 +94,9 @@ function makeStorageStub(initial, onOp) {
                 ? structuredClone(store)
                 : structuredClone(store[key]),
         // Seed or replace a record without going through the module under
-        // test — for standing in as "another page wrote this".
+        // test — for standing in as "another page wrote this". Nothing is
+        // announced to storage.onChanged, so it also stands in for the time
+        // before the browser tells this page of such a write.
         write: (key, value) => {
             store[key] = structuredClone(value);
         },

tests/symbolSpoof.test.js

@@ -52,8 +52,14 @@ jest.mock("../src/shared/log", () => ({
 global.fetch = jest.fn(() => {
     throw new Error("tests must not perform network requests");
 });
+// Blockscout is asked only while the stored "Use Blockscout" is on.
 global.chrome = {
-    storage: { local: { get: async () => ({}), set: async () => {} } },
+    storage: {
+        local: {
+            get: async () => ({ autistmask: { useBlockscout: true } }),
+            set: async () => {},
+        },
+    },
 };
 
 const { isSpoofedSymbol } = require("../src/shared/symbolSpoof");
@@ -485,8 +491,12 @@ describe("surface 2: the Send token selector", () => {
     function render(tokenBalances) {
         select = { innerHTML: "", children: [] };
         select.appendChild = (child) => select.children.push(child);
+        const elements = {
+            "send-token": select,
+            "send-tokens-note": { classList: { toggle: () => {} } },
+        };
         globalThis.document = {
-            getElementById: (id) => (id === "send-token" ? select : null),
+            getElementById: (id) => elements[id] || null,
             createElement: () => ({ value: "", textContent: "" }),
         };
         renderSendTokenSelect({

tests/timestampDisplay.test.js

@@ -134,6 +134,8 @@ beforeEach(() => {
     state.selectedWallet = 0;
     state.selectedAddress = 0;
     state.selectedToken = "ETH";
+    // The history is Blockscout's.
+    state.useBlockscout = true;
 });
 
 describe.each([

tests/tokenTransferDetail.test.js

@@ -38,8 +38,14 @@ jest.mock("../src/shared/log", () => ({
     isDebug: () => false,
 }));
 
+// Blockscout is asked only while the stored "Use Blockscout" is on.
 globalThis.chrome = {
-    storage: { local: { get: async () => ({}), set: async () => {} } },
+    storage: {
+        local: {
+            get: async () => ({ autistmask: { useBlockscout: true } }),
+            set: async () => {},
+        },
+    },
 };
 
 const { state } = require("../src/shared/state");
@@ -158,6 +164,7 @@ beforeEach(() => {
     globalThis.document = makeDocument();
     globalThis.window = { location: { search: "" } };
     state.blockscoutUrl = EXPLORER;
+    state.useBlockscout = true;
     state.networkEndpoints = {};
     state.wallets = [
         {

tests/trackedTokenBalances.test.js

@@ -0,0 +1,309 @@
+// The balance of each token the user tracks is read with balanceOf through the
+// RPC endpoint, for every address. Blockscout's answer gives a tracked token its
+// holder count and decimals, and adds the tokens the user has not tracked
+// (https://git.eeqj.de/sneak/AutistMask/issues/669).
+//
+// The real refreshBalances() runs against a fake JSON-RPC node, answered
+// through ethers' own request hook, and a fake Blockscout, answered through
+// fetch().
+
+const { AbiCoder, FetchRequest } = require("ethers");
+const { refreshBalances } = require("../src/shared/balances");
+const { makeStorageStub } = require("./support/storageStub");
+
+// Blockscout is asked only while the stored "Use Blockscout" is on.
+globalThis.chrome = {
+    storage: makeStorageStub({ autistmask: { useBlockscout: true } }),
+};
+
+const RPC_URL = "https://rpc.example.invalid";
+const EXPLORER_URL = "https://explorer.example.invalid/api/v2";
+const FIRST = "0x1111111111111111111111111111111111111111";
+const SECOND = "0x2222222222222222222222222222222222222222";
+
+// A token the user tracks, outside the bundled list, at 6 decimals.
+const TOKEN = "0x7777777777777777777777777777777777777777";
+const TRACKED = {
+    address: TOKEN,
+    symbol: "TRK",
+    name: "Tracked Token",
+    decimals: 6,
+};
+
+// USDC, from the bundled list, which the user does not track.
+const USDC = "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48";
+// Neither on the bundled list nor tracked.
+const OTHER = "0x8888888888888888888888888888888888888888";
+
+const ZERO_WORD = "0x" + "0".repeat(64);
+const BALANCE_OF = "0x70a08231";
+
+// What balanceOf answers, by token contract and then by holder. A pair that is
+// not here makes balanceOf fail.
+let holdings;
+// What Blockscout answers for every address; null makes the request fail.
+let explorerRows;
+let logged;
+
+// One JSON-RPC answer. A call that is not balanceOf is the ENS reverse lookup,
+// answered with no resolver, so no name.
+function reply(req) {
+    const envelope = { jsonrpc: "2.0", id: req.id };
+    if (req.method === "eth_getBalance") {
+        return { ...envelope, result: "0x0" };
+    }
+    if (req.method !== "eth_call") {
+        return {
+            ...envelope,
+            error: { code: -32601, message: "method not found" },
+        };
+    }
+    const { to, data } = req.params[0];
+    if (!data.startsWith(BALANCE_OF)) return { ...envelope, result: ZERO_WORD };
+    const holder = "0x" + data.slice(-40);
+    const amount = (holdings[to.toLowerCase()] || {})[holder];
+    if (amount === undefined) {
+        return {
+            ...envelope,
+            error: { code: -32000, message: "fixture: balanceOf failed" },
+        };
+    }
+    return {
+        ...envelope,
+        result: AbiCoder.defaultAbiCoder().encode(["uint256"], [amount]),
+    };
+}
+
+const realFetch = globalThis.fetch;
+
+beforeEach(() => {
+    holdings = {};
+    explorerRows = null;
+    logged = [];
+    jest.spyOn(console, "error").mockImplementation((...args) => {
+        logged.push(args.map(String).join(" "));
+    });
+    FetchRequest.registerGetUrl(async (req) => {
+        const body = JSON.parse(Buffer.from(req.body).toString("utf8"));
+        const answer = Array.isArray(body) ? body.map(reply) : reply(body);
+        return {
+            statusCode: 200,
+            statusMessage: "OK",
+            headers: { "content-type": "application/json" },
+            body: Buffer.from(JSON.stringify(answer)),
+        };
+    });
+    globalThis.fetch = jest.fn(async () => {
+        if (explorerRows === null) throw new TypeError("Failed to fetch");
+        return { ok: true, status: 200, json: async () => explorerRows };
+    });
+});
+
+afterEach(() => {
+    FetchRequest.registerGetUrl(FetchRequest.createGetUrlFunc());
+    globalThis.fetch = realFetch;
+    jest.restoreAllMocks();
+});
+
+// One Blockscout token-balances row.
+function explorerRow(address, symbol, value, holders = "50000") {
+    return {
+        value: String(value),
+        token: {
+            type: "ERC-20",
+            address_hash: address,
+            symbol: symbol,
+            name: symbol,
+            decimals: "6",
+            holders_count: holders,
+        },
+    };
+}
+
+// The row refreshBalances() writes for TOKEN from a balanceOf answer, with the
+// decimals and holder count Blockscout reported for it, if any.
+function trackedRow(balance, decimals = null, holders = null) {
+    return {
+        address: TOKEN,
+        name: "Tracked Token",
+        symbol: "TRK",
+        decimals: decimals,
+        balance: balance,
+        holders: holders,
+    };
+}
+
+async function refresh(addresses, trackedTokens) {
+    await refreshBalances(
+        [{ addresses }],
+        RPC_URL,
+        EXPLORER_URL,
+        trackedTokens,
+        "mainnet",
+        new AbortController().signal,
+    );
+    return addresses;
+}
+
+test("with Blockscout failing, a tracked token's balance is read through the RPC endpoint for every address", async () => {
+    holdings[TOKEN] = { [FIRST]: 1234500000n, [SECOND]: 1n };
+    const [first, second] = await refresh(
+        [
+            { address: FIRST, tokenBalances: [] },
+            { address: SECOND, tokenBalances: [] },
+        ],
+        [TRACKED],
+    );
+    expect(first.tokenBalances).toEqual([trackedRow("1234.5")]);
+    // Exact, never cut: one base unit is not zero.
+    expect(second.tokenBalances).toEqual([trackedRow("0.000001")]);
+});
+
+test("with Blockscout failing, the untracked rows from before stay", async () => {
+    holdings[TOKEN] = { [FIRST]: 2000000n };
+    const usdc = {
+        address: USDC,
+        name: "USD Coin",
+        symbol: "USDC",
+        decimals: 6,
+        balance: "5.0",
+        holders: 50000,
+    };
+    const [first] = await refresh(
+        [{ address: FIRST, tokenBalances: [usdc] }],
+        [TRACKED],
+    );
+    expect(first.tokenBalances).toEqual([trackedRow("2.0"), usdc]);
+});
+
+test("a tracked token Blockscout also reports shows the RPC figure, and an untracked one is admitted as before", async () => {
+    holdings[TOKEN] = { [FIRST]: 2000000n };
+    explorerRows = [
+        explorerRow(TOKEN, "TRK", 9000000),
+        explorerRow(USDC, "USDC", 5000000),
+        // Too few holders, and neither on the bundled list nor tracked.
+        explorerRow(OTHER, "SPAM", 5000000, "10"),
+        // A known symbol from a contract it does not belong to.
+        explorerRow(OTHER, "USDC", 5000000),
+    ];
+    const [first] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        [TRACKED],
+    );
+    expect(first.tokenBalances).toEqual([
+        trackedRow("2.0", 6, 50000),
+        {
+            address: USDC,
+            name: "USDC",
+            symbol: "USDC",
+            decimals: 6,
+            balance: "5.0",
+            holders: 50000,
+        },
+    ]);
+});
+
+test("a tracked token's entry carries the holder count and decimals Blockscout reports for it", async () => {
+    holdings[TOKEN] = { [FIRST]: 2000000n };
+    // Fewer holders than "Hide tokens with fewer than 1,000 holders" lets
+    // through to Send's token list.
+    explorerRows = [explorerRow(TOKEN, "TRK", 9000000, "10")];
+    const [first] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        [TRACKED],
+    );
+    expect(first.tokenBalances).toEqual([trackedRow("2.0", 6, 10)]);
+});
+
+test("while Blockscout fails, a tracked token keeps the holder count and decimals of its entry from before", async () => {
+    holdings[TOKEN] = { [FIRST]: 2000000n };
+    const [first] = await refresh(
+        [{ address: FIRST, tokenBalances: [trackedRow("7.0", 6, 10)] }],
+        [TRACKED],
+    );
+    expect(first.tokenBalances).toEqual([trackedRow("2.0", 6, 10)]);
+});
+
+test("a failed balanceOf keeps the token's entry from before, and is logged", async () => {
+    explorerRows = [explorerRow(TOKEN, "TRK", 9000000)];
+    const before = trackedRow("7.0", 6, 50000);
+    const [first] = await refresh(
+        [{ address: FIRST, tokenBalances: [before] }],
+        [TRACKED],
+    );
+    expect(first.tokenBalances).toEqual([before]);
+    expect(logged.some((line) => line.includes("token balance failed"))).toBe(
+        true,
+    );
+});
+
+test("a failed balanceOf with no entry from before takes Blockscout's entry from this refresh", async () => {
+    // balanceOf fails at FIRST and answers at SECOND.
+    holdings[TOKEN] = { [SECOND]: 2000000n };
+    explorerRows = [explorerRow(TOKEN, "TRK", 9000000)];
+    const [first, second] = await refresh(
+        [
+            { address: FIRST, tokenBalances: [] },
+            { address: SECOND, tokenBalances: [] },
+        ],
+        [TRACKED],
+    );
+    expect(first.tokenBalances).toEqual([
+        {
+            address: TOKEN,
+            name: "TRK",
+            symbol: "TRK",
+            decimals: 6,
+            balance: "9.0",
+            holders: 50000,
+        },
+    ]);
+    // Where balanceOf answers, its figure stands.
+    expect(second.tokenBalances).toEqual([trackedRow("2.0", 6, 50000)]);
+});
+
+test("a balance of zero read through the RPC endpoint replaces the previous figure", async () => {
+    holdings[TOKEN] = { [FIRST]: 0n };
+    const [first] = await refresh(
+        [{ address: FIRST, tokenBalances: [trackedRow("7.0")] }],
+        [TRACKED],
+    );
+    expect(first.tokenBalances).toEqual([]);
+});
+
+test("a tracked token whose scale nothing knows gets no quantity, not a zero", async () => {
+    holdings[TOKEN] = { [FIRST]: 5n };
+    const [first] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        [{ ...TRACKED, decimals: null }],
+    );
+    expect(first.tokenBalances).toEqual([trackedRow(null)]);
+});
+
+test("a tracked token whose scale only Blockscout reports is stated at that scale", async () => {
+    holdings[TOKEN] = { [FIRST]: 2000000n };
+    explorerRows = [explorerRow(TOKEN, "TRK", 9000000)];
+    const [first] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        [{ ...TRACKED, decimals: null }],
+    );
+    expect(first.tokenBalances).toEqual([trackedRow("2.0", 6, 50000)]);
+});
+
+test("a tracked token wearing a known symbol from another contract is not listed", async () => {
+    holdings[OTHER] = { [FIRST]: 5000000n };
+    // Its entry from before goes too, although Blockscout fails.
+    const before = {
+        address: OTHER,
+        name: "Fake",
+        symbol: "USDC",
+        decimals: 6,
+        balance: "5.0",
+        holders: 50000,
+    };
+    const [first] = await refresh(
+        [{ address: FIRST, tokenBalances: [before] }],
+        [{ address: OTHER, symbol: "USDC", name: "Fake", decimals: 6 }],
+    );
+    expect(first.tokenBalances).toEqual([]);
+});

tests/trackedTokensPerNetwork.test.js

@@ -161,6 +161,7 @@ test("a token added by contract address on Sepolia is tracked on Sepolia only",
     );
     expect(stored().trackedTokens).toEqual([SEPOLIA_TOKEN]);
 
+    await boot.click("btn-settings");
     await chooseNetwork(boot, "mainnet");
     expect(stored().networkId).toBe("mainnet");
     expect(stored().trackedTokens).toEqual([MAINNET_TOKEN]);
@@ -286,6 +287,7 @@ describe("Back after a switch from the Settings gear", () => {
                 currentView: "confirm-tx",
                 selectedWallet: 0,
                 selectedAddress: 0,
+                checkRecipientsOnEtherscan: true,
                 viewData: {
                     pendingTx: {
                         token: "ETH",

tests/transactionListCancelled.test.js

@@ -125,6 +125,8 @@ beforeEach(() => {
     state.selectedWallet = 0;
     state.selectedAddress = 0;
     state.selectedToken = "ETH";
+    // The history is Blockscout's.
+    state.useBlockscout = true;
 });
 
 afterEach(() => {

tests/transactions.test.js

@@ -1215,6 +1215,8 @@ function respondWith(txItems, tokenTransferItems) {
 describe("fetchRecentTransactions merge and dedup", () => {
     beforeEach(() => {
         debugFetch.mockReset();
+        // Blockscout is asked only while the stored "Use Blockscout" is on.
+        global.chrome.storage.write("autistmask", { useBlockscout: true });
     });
 
     test("queries only the two Blockscout endpoints for the address", async () => {

tests/uniswap.test.js

@@ -1912,7 +1912,9 @@ describe("uniswap decoder", () => {
                         ],
                     ),
                 ],
-                first: USDT_400_GROUP,
+                // Nothing read says the user pays this step, so its 400 USDT
+                // gets no lines of its own.
+                first: [],
             },
             {
                 kind: "a V3 step of 600 USDT, then a V4 step whose input cannot be read",
@@ -2106,12 +2108,6 @@ describe("uniswap decoder", () => {
         const ONE_USDT_LINES = (spender) =>
             permitLines("1.0000 USDT", USDT_ADDR, "USDT", spender);
         test.each([
-            {
-                kind: "to another spender",
-                commands: [0x0a],
-                permits: [ONE_USDT_PERMIT(OTHER_ADDR)],
-                lines: ONE_USDT_LINES(OTHER_ADDR),
-            },
             {
                 kind: "that the router lets fail",
                 commands: [0x8a],
@@ -2331,6 +2327,103 @@ describe("uniswap decoder", () => {
             expect(linesBetweenTokens(result)).toEqual(lines);
         });
 
+        // A step that sets the input side and is paid from the router takes
+        // nothing from the sender, so with no Amount line its amount gets no
+        // lines of its own: in each route below the sender's 600 USDT moves
+        // into the router first, and such lines would say it left twice.
+        const INTO_ROUTER_600 = permit2TransferFrom(
+            USDT_ADDR,
+            ROUTER_ADDR,
+            USDT_600,
+        );
+        const V3_600_FROM_ROUTER = coder.encode(
+            ["address", "uint256", "uint256", "bytes", "bool"],
+            [
+                USER_ADDR,
+                USDT_600,
+                590000000n,
+                encodeV3Path([USDT_ADDR, USDC_ADDR]),
+                false,
+            ],
+        );
+        const TRANSFER_FROM_BATCH = coder.encode(
+            ["tuple(address,address,uint160,address)[]"],
+            [[[USER_ADDR, OTHER_ADDR, USDT_400, USDT_ADDR]]],
+        );
+        test.each([
+            {
+                kind: "a PERMIT2_TRANSFER_FROM of 600 USDT into the router, a V3 exact-in of 600 USDT paid from the router, then a PERMIT2_TRANSFER_FROM_BATCH",
+                commands: [0x02, 0x00, 0x0d],
+                inputs: [
+                    INTO_ROUTER_600,
+                    V3_600_FROM_ROUTER,
+                    TRANSFER_FROM_BATCH,
+                ],
+                lines: [["Moved from the sender", UNDECODED]],
+            },
+            {
+                kind: "a PERMIT2_PERMIT that cannot be read, a PERMIT2_TRANSFER_FROM of 600 USDT into the router, then a V3 exact-in of 600 USDT paid from the router",
+                commands: [0x0a, 0x02, 0x00],
+                inputs: [
+                    dirtyWord(
+                        encodePermit2(USDT_ADDR, 5000000000n, ROUTER_ADDR),
+                        0,
+                    ),
+                    INTO_ROUTER_600,
+                    V3_600_FROM_ROUTER,
+                ],
+                lines: [["Permit2 allowance", UNDECODED]],
+            },
+            {
+                kind: "a PERMIT2_TRANSFER_FROM of 600 USDT into the router, a V4 step swapping 600 USDT whose SETTLE the router pays, then a PERMIT2_TRANSFER_FROM_BATCH",
+                commands: [0x02, 0x10, 0x0d],
+                inputs: [
+                    INTO_ROUTER_600,
+                    encodeV4Swap(
+                        new Uint8Array([
+                            V4_SWAP_EXACT_IN_SINGLE_ID,
+                            V4_SETTLE_ID,
+                            V4_TAKE_ALL_ID,
+                        ]),
+                        [
+                            encodeV4ExactInSingle(
+                                USDT_ADDR,
+                                USDC_ADDR,
+                                USDT_600,
+                                590000000n,
+                            ),
+                            settle(USDT_ADDR, USDT_600, false),
+                            encodeV4TakeAll(USDC_ADDR, 0n),
+                        ],
+                    ),
+                    TRANSFER_FROM_BATCH,
+                ],
+                lines: [["Moved from the sender", UNDECODED]],
+            },
+            {
+                kind: "a PERMIT2_TRANSFER_FROM of 600 USDT into the router, a V2 exact-in of CONTRACT_BALANCE paid from the router, then an EXECUTE_SUB_PLAN",
+                commands: [0x02, 0x08, 0x21],
+                inputs: [
+                    INTO_ROUTER_600,
+                    coder.encode(
+                        ["address", "uint256", "uint256", "address[]", "bool"],
+                        [
+                            USER_ADDR,
+                            2n ** 255n, // CONTRACT_BALANCE
+                            590000000n,
+                            [USDT_ADDR, USDC_ADDR],
+                            false,
+                        ],
+                    ),
+                    SUB_PLAN,
+                ],
+                lines: [["Moved from the sender", UNDECODED]],
+            },
+        ])("$kind", ({ commands, inputs, lines }) => {
+            const result = decodeSteps(commands, inputs);
+            expect(linesBetweenTokens(result)).toEqual(lines);
+        });
+
         // A V3_SWAP_EXACT_OUT the user pays for, of at most `amountInMax`
         // USDT for USDC.
         const v3ExactOut = (amountInMax) =>
@@ -2451,20 +2544,6 @@ describe("uniswap decoder", () => {
                     ],
                     lines: USDT_600_LINES,
                 },
-                {
-                    kind: "a PERMIT2_PERMIT of 5,000 USDT to another spender, then a V3 exact-in of 600 USDT,",
-                    commands: [0x0a, 0x00],
-                    inputs: [
-                        encodePermit2(USDT_ADDR, USDT_5000, OTHER_ADDR),
-                        V3_600,
-                    ],
-                    lines: permitLines(
-                        "5000.0000 USDT",
-                        USDT_ADDR,
-                        "USDT",
-                        OTHER_ADDR,
-                    ),
-                },
                 {
                     kind: "a PERMIT2_PERMIT of 5,000 USDT to the router that the router may let fail, then a V3 exact-in of 600 USDT,",
                     commands: [0x8a, 0x00],
@@ -2578,45 +2657,41 @@ describe("uniswap decoder", () => {
             const DAI_5000 = 5000000000000000000000n;
             const MAX_UINT160 = 2n ** 160n - 1n;
 
-            // A batch names one spender for all its allowances.
-            test.each([
-                { kind: "the router", spender: ROUTER_ADDR },
-                { kind: "another spender", spender: OTHER_ADDR },
-            ])(
-                "a PERMIT2_PERMIT_BATCH of 5,000 USDT and unlimited DAI to $kind, then a V3 exact-in of 600 USDT, shows each allowance",
-                ({ spender }) => {
-                    const result = decodeSteps(
-                        [0x03, 0x00],
-                        [
-                            encodePermit2Batch(
-                                [
-                                    [USDT_ADDR, USDT_5000],
-                                    [DAI_ADDR, MAX_UINT160],
-                                ],
-                                spender,
-                            ),
-                            V3_600,
-                        ],
-                    );
-                    expect(result.name).toBe("Swap USDT → USDC");
-                    expect(linesBetweenTokens(result)).toEqual([
-                        ["Amount", "600.0000 USDT"],
-                        ...permitLines(
-                            "5000.0000 USDT",
-                            USDT_ADDR,
-                            "USDT",
-                            spender,
+            // A batch names one spender for all its allowances. One to
+            // another spender is under "an allowance to a spender other than
+            // the router" below.
+            test("a PERMIT2_PERMIT_BATCH of 5,000 USDT and unlimited DAI to the router, then a V3 exact-in of 600 USDT, shows each allowance", () => {
+                const result = decodeSteps(
+                    [0x03, 0x00],
+                    [
+                        encodePermit2Batch(
+                            [
+                                [USDT_ADDR, USDT_5000],
+                                [DAI_ADDR, MAX_UINT160],
+                            ],
+                            ROUTER_ADDR,
                         ),
-                        ...permitLines("Unlimited", DAI_ADDR, "DAI", spender),
-                    ]);
-                    // A batch pays nobody, so the swap's minimum is what the
-                    // sender receives.
-                    expect(detail(result, "Paid to")).toBeUndefined();
-                    expect(detail(result, "Min. received").value).toBe(
-                        "590.0000 USDC",
-                    );
-                },
-            );
+                        V3_600,
+                    ],
+                );
+                expect(result.name).toBe("Swap USDT → USDC");
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "600.0000 USDT"],
+                    ...permitLines(
+                        "5000.0000 USDT",
+                        USDT_ADDR,
+                        "USDT",
+                        ROUTER_ADDR,
+                    ),
+                    ...permitLines("Unlimited", DAI_ADDR, "DAI", ROUTER_ADDR),
+                ]);
+                // A batch pays nobody, so the swap's minimum is what the
+                // sender receives.
+                expect(detail(result, "Paid to")).toBeUndefined();
+                expect(detail(result, "Min. received").value).toBe(
+                    "590.0000 USDC",
+                );
+            });
 
             // A batch keeps a PERMIT2_PERMIT's amount from standing as the
             // Amount figure, before the permit as after it.
@@ -2669,7 +2744,7 @@ describe("uniswap decoder", () => {
                     ),
                 },
             ])(
-                "$kind that cannot be read, then a V3 exact-in of 600 USDT, says its allowances could not be decoded and shows no Amount figure",
+                "$kind that cannot be read, then a V3 exact-in of 600 USDT, says its allowances could not be decoded and shows no Amount figure and no Min. received",
                 ({ command, input }) => {
                     const result = decodeSteps(
                         [command, 0x00],
@@ -2679,6 +2754,14 @@ describe("uniswap decoder", () => {
                         ...USDT_600_GROUP,
                         ["Permit2 allowance", UNDECODED],
                     ]);
+                    // Its spender may be any address, as with an allowance
+                    // to a spender other than the router (below).
+                    // https://git.eeqj.de/sneak/AutistMask/issues/658 — on
+                    // next at e296546 this read Min. received.
+                    expect(detail(result, "Min. received")).toBeUndefined();
+                    expect(detail(result, "Min. paid out").value).toBe(
+                        "590.0000 USDC",
+                    );
                 },
             );
 
@@ -2707,6 +2790,125 @@ describe("uniswap decoder", () => {
             });
         });
 
+        // https://git.eeqj.de/sneak/AutistMask/issues/658 — code that a step
+        // runs can call a spender other than the router, which can then take
+        // up to its allowance from the sender before the transaction ends.
+        // On next at e296546 the Amount figure and Min. received took no
+        // account of it. An allowance of Token In to another spender now
+        // leaves no Amount figure, the swap steps' own takes get lines of
+        // their own, and any allowance to another spender leaves no Min.
+        // received.
+        describe("an allowance to a spender other than the router", () => {
+            const USDT_5000 = 5000000000n;
+            const DAI_5000 = 5000000000000000000000n;
+            const MAX_UINT160 = 2n ** 160n - 1n;
+            const USDT_5000_LINES = permitLines(
+                "5000.0000 USDT",
+                USDT_ADDR,
+                "USDT",
+                OTHER_ADDR,
+            );
+
+            test.each([
+                {
+                    kind: "a PERMIT2_PERMIT of 5,000 USDT to another spender, then a V3 exact-in of 600 USDT,",
+                    commands: [0x0a, 0x00],
+                    inputs: [
+                        encodePermit2(USDT_ADDR, USDT_5000, OTHER_ADDR),
+                        V3_600,
+                    ],
+                    lines: [...USDT_600_GROUP, ...USDT_5000_LINES],
+                    minimum: "590.0000 USDC",
+                },
+                {
+                    kind: "a V3 exact-in of 600 USDT, then a PERMIT2_PERMIT of 5,000 USDT to another spender,",
+                    commands: [0x00, 0x0a],
+                    inputs: [
+                        V3_600,
+                        encodePermit2(USDT_ADDR, USDT_5000, OTHER_ADDR),
+                    ],
+                    lines: [...USDT_600_GROUP, ...USDT_5000_LINES],
+                    minimum: "590.0000 USDC",
+                },
+                {
+                    kind: "a PERMIT2_PERMIT_BATCH of 5,000 USDT and unlimited DAI to another spender, then a V3 exact-in of 600 USDT,",
+                    commands: [0x03, 0x00],
+                    inputs: [
+                        encodePermit2Batch(
+                            [
+                                [USDT_ADDR, USDT_5000],
+                                [DAI_ADDR, MAX_UINT160],
+                            ],
+                            OTHER_ADDR,
+                        ),
+                        V3_600,
+                    ],
+                    lines: [
+                        ...USDT_600_GROUP,
+                        ...USDT_5000_LINES,
+                        ...permitLines(
+                            "Unlimited",
+                            DAI_ADDR,
+                            "DAI",
+                            OTHER_ADDR,
+                        ),
+                    ],
+                    minimum: "590.0000 USDC",
+                },
+                {
+                    kind: "a PERMIT2_PERMIT of 1 USDT to another spender, then a V3 exact-in of 600 USDT and a V2 exact-in of 400 USDT, both paid by the user,",
+                    commands: [0x0a, 0x00, 0x08],
+                    inputs: [
+                        ONE_USDT_PERMIT(OTHER_ADDR),
+                        V3_600,
+                        encodeV2SwapExactIn(USER_ADDR, USDT_400, 390000000n, [
+                            USDT_ADDR,
+                            USDC_ADDR,
+                        ]),
+                    ],
+                    lines: [
+                        ...USDT_600_GROUP,
+                        ...USDT_400_GROUP,
+                        ...ONE_USDT_LINES(OTHER_ADDR),
+                    ],
+                    // The last swap step's minimum.
+                    minimum: "390.0000 USDC",
+                },
+            ])(
+                "$kind shows each take's own lines and the allowances, and no Amount figure or Min. received",
+                ({ commands, inputs, lines, minimum }) => {
+                    const result = decodeSteps(commands, inputs);
+                    expect(result.name).toBe("Swap USDT → USDC");
+                    expect(linesBetweenTokens(result)).toEqual(lines);
+                    expect(detail(result, "Paid to")).toBeUndefined();
+                    expect(detail(result, "Min. received")).toBeUndefined();
+                    expect(detail(result, "Min. paid out").value).toBe(minimum);
+                },
+            );
+
+            // An allowance of another token leaves the Amount figure for
+            // Token In.
+            test("a PERMIT2_PERMIT of 5,000 DAI to another spender, then a V3 exact-in of 600 USDT, shows the swap's 600 USDT and no Min. received", () => {
+                const result = decodeSteps(
+                    [0x0a, 0x00],
+                    [encodePermit2(DAI_ADDR, DAI_5000, OTHER_ADDR), V3_600],
+                );
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "600.0000 USDT"],
+                    ...permitLines(
+                        "5000.0000 DAI",
+                        DAI_ADDR,
+                        "DAI",
+                        OTHER_ADDR,
+                    ),
+                ]);
+                expect(detail(result, "Min. received")).toBeUndefined();
+                expect(detail(result, "Min. paid out").value).toBe(
+                    "590.0000 USDC",
+                );
+            });
+        });
+
         // A V3_SWAP_EXACT_OUT whose path is shorter than one token cannot be
         // read. It may pay any address and take from the sender, so it
         // leaves no Amount figure.
@@ -3528,6 +3730,88 @@ describe("uniswap decoder", () => {
         },
     );
 
+    // https://git.eeqj.de/sneak/AutistMask/issues/574 — a V4 step that buys
+    // at least 0.5 WETH with 1,000 USDT, spends some of it on USDC, and takes
+    // the USDC and then the WETH, so its output side is WETH. Only what is
+    // left of the 0.5 WETH is sure to reach the user, and the screen read
+    // Min. received 0.5000 WETH.
+    test.each([
+        {
+            spend: "0.3 WETH for at least 594 USDC",
+            swap: {
+                id: V4_SWAP_EXACT_IN_SINGLE_ID,
+                param: encodeV4ExactInSingle(
+                    WETH_ADDR,
+                    USDC_ADDR,
+                    300000000000000000n,
+                    594000000n,
+                ),
+            },
+        },
+        {
+            spend: "0.3 WETH through DAI for at least 594 USDC",
+            swap: {
+                id: V4_SWAP_EXACT_IN,
+                param: encodeV4ExactIn(
+                    WETH_ADDR,
+                    [DAI_ADDR, USDC_ADDR],
+                    300000000000000000n,
+                    594000000n,
+                ),
+            },
+        },
+        {
+            spend: "at most 0.3 WETH for exactly 594 USDC",
+            swap: {
+                id: V4_SWAP_EXACT_OUT_SINGLE_ID,
+                param: encodeV4ExactOutSingle(
+                    WETH_ADDR,
+                    USDC_ADDR,
+                    594000000n,
+                    300000000000000000n,
+                ),
+            },
+        },
+    ])(
+        "a V4 step that buys WETH and spends $spend, with WETH as its output side, shows no Min. received",
+        ({ swap }) => {
+            const data = buildExecute(
+                "0x10",
+                [
+                    encodeV4Swap(
+                        new Uint8Array([
+                            USDT_FOR_WETH_IN.id,
+                            swap.id,
+                            V4_SETTLE_ALL_ID,
+                            V4_TAKE_ID,
+                            V4_TAKE_ID,
+                        ]),
+                        [
+                            USDT_FOR_WETH_IN.param,
+                            swap.param,
+                            encodeV4SettleAll(USDT_ADDR, 1000000000n),
+                            encodeV4Take(USDC_ADDR),
+                            encodeV4Take(WETH_ADDR),
+                        ],
+                    ),
+                ],
+                9999999999n,
+            );
+
+            const result = uniswap.decode(
+                data,
+                ROUTER_ADDR,
+                "0x1",
+                {},
+                USER_ADDR,
+            );
+            expect(result.name).toBe("Swap USDT → WETH");
+            expect(detail(result, "Amount").value).toBe("1000.0000 USDT");
+            expect(detail(result, "Token Out").address).toBe(WETH_ADDR);
+            expect(detail(result, "Min. received")).toBeUndefined();
+        },
+    );
+
     // A V4 step that spends WETH on USDC and on DAI. Its swap actions buy two
     // currencies that none of them spends, and CLOSE_CURRENCY, which the
     // decoder does not read, names no side, so its output side is unknown.

tests/uniswapRecipient.test.js

@@ -42,8 +42,14 @@ jest.mock("../src/shared/log", () => ({
     isDebug: () => false,
 }));
 
+// Blockscout is asked only while the stored "Use Blockscout" is on.
 globalThis.chrome = {
-    storage: { local: { get: async () => ({}), set: async () => {} } },
+    storage: {
+        local: {
+            get: async () => ({ autistmask: { useBlockscout: true } }),
+            set: async () => {},
+        },
+    },
 };
 
 const uniswap = require("../src/shared/uniswap");
@@ -1332,6 +1338,10 @@ describe("any token left in the router is not received", () => {
                 ),
             ),
             left: tokenLine(WETH, "WETH"),
+            // The second swap action spends 1 USDC of what the first buys,
+            // so the step states no minimum
+            // (https://git.eeqj.de/sneak/AutistMask/issues/574).
+            noMin: true,
         },
         {
             kind: "a WRAP_ETH of 1 ETH into the router, then a V4 SETTLE of OPEN_DELTA from the router before the swap, which the user settles",
@@ -1432,7 +1442,7 @@ describe("any token left in the router is not received", () => {
             ),
             left: { label: "Token moved into the router", value: "ETH" },
         },
-    ])("$kind", ({ data, left, spent, unread }) => {
+    ])("$kind", ({ data, left, spent, unread, noMin }) => {
         const result = decode(data);
         expect(labels(result)).toEqual([
             "Protocol",
@@ -1458,7 +1468,7 @@ describe("any token left in the router is not received", () => {
             "Token Out",
             "Paid to",
             "Token moved into the router",
-            "Min. paid out",
+            ...(noMin ? [] : ["Min. paid out"]),
             "Steps",
             "Deadline",
         ]);
@@ -1474,7 +1484,9 @@ describe("any token left in the router is not received", () => {
         }
         expect(paidTo(result)).toEqual([STAYS_IN_ROUTER]);
         expect(detail(result, "Token moved into the router")).toEqual(left);
-        expect(detail(result, "Min. paid out").value).toBe("1990.0000 USDC");
+        expect(detail(result, "Min. paid out")?.value).toBe(
+            noMin ? undefined : "1990.0000 USDC",
+        );
     });
 
     // Uniswap's own routes: a swap paid in ETH wraps into the router what its
@@ -2802,26 +2814,37 @@ describe("the allow-revert flag", () => {
     });
 
     // Only the routers from UniversalRouterV2 on let a PERMIT2_PERMIT fail.
+    // The permit's spender is the router at ROUTER, which on every other
+    // router is an allowance to another spender, so the minimum reads
+    // Min. paid out there.
     test.each([
-        { router: "UniversalRouterV1", address: ROUTER_V1, mark: "" },
+        {
+            router: "UniversalRouterV1",
+            address: ROUTER_V1,
+            mark: "",
+            minimum: "Min. paid out",
+        },
         {
             router: "UniversalRouterV1_2_V2Support",
             address: ROUTER_V1_2,
             mark: "",
+            minimum: "Min. paid out",
         },
         {
             router: "UniversalRouterV2",
             address: ROUTER,
             mark: " (allowed to fail)",
+            minimum: "Min. received",
         },
         {
             router: "UniversalRouterV2_1_2",
             address: ROUTER_V2_1_2,
             mark: " (allowed to fail)",
+            minimum: "Min. paid out",
         },
     ])(
         "on $router, a PERMIT2_PERMIT with the flag is listed as 'Permit2 Permit$mark', and the swap's lines read as without the flag",
-        ({ address, mark }) => {
+        ({ address, mark, minimum }) => {
             const steps = [
                 permit2Permit(USDT, USDT_2000),
                 swapToWeth(MSG_SENDER),
@@ -2853,7 +2876,7 @@ describe("the allow-revert flag", () => {
             expect(
                 labels(withFlag).filter((l) => permitLines.includes(l)),
             ).toEqual(permitLines);
-            expect(detail(withFlag, "Min. received").value).toBe("1.0000 WETH");
+            expect(detail(withFlag, minimum).value).toBe("1.0000 WETH");
         },
     );
 
@@ -3439,6 +3462,7 @@ async function showDetail(data) {
     globalThis.window = { location: { search: "" } };
     state.networkId = "mainnet";
     state.blockscoutUrl = "https://explorer.example/api/v2";
+    state.useBlockscout = true;
     state.viewData = {};
     state.viewStack = [];
     state.currentView = null;

tests/uniswapRouterAddress.test.js

@@ -34,8 +34,14 @@ jest.mock("../src/shared/log", () => ({
     isDebug: () => false,
 }));
 
+// Blockscout is asked only while the stored "Use Blockscout" is on.
 globalThis.chrome = {
-    storage: { local: { get: async () => ({}), set: async () => {} } },
+    storage: {
+        local: {
+            get: async () => ({ autistmask: { useBlockscout: true } }),
+            set: async () => {},
+        },
+    },
 };
 
 const { state } = require("../src/shared/state");
@@ -208,6 +214,7 @@ async function showDetail(row, activeNetworkId) {
     globalThis.window = { location: { search: "" } };
     state.networkId = activeNetworkId;
     state.blockscoutUrl = "https://explorer.example/api/v2";
+    state.useBlockscout = true;
     state.viewData = {};
     state.viewStack = [];
     state.currentView = null;

tests/uniswapUnknownDecimals.test.js

@@ -90,6 +90,9 @@ function swapDetail(data, label) {
 beforeEach(() => {
     state.trackedTokens = [];
     state.wallets = [];
+    // The approval screen reads the explorer's report only while "Use
+    // Blockscout" is on.
+    state.useBlockscout = true;
 });
 
 describe("a swap of a token outside the bundled list", () => {

tests/unknownScaleSend.test.js

@@ -72,8 +72,12 @@ global.fetch = jest.fn(() => {
     throw new Error("tests must not perform network requests");
 });
 
+// Blockscout is asked only while the stored "Use Blockscout" is on.
 const { makeStorageStub } = require("./support/storageStub");
-global.chrome = { storage: makeStorageStub(), runtime: { sendMessage() {} } };
+global.chrome = {
+    storage: makeStorageStub({ autistmask: { useBlockscout: true } }),
+    runtime: { sendMessage() {} },
+};
 
 // A stub DOM. Every id in index.html that these two views touch resolves to a
 // fresh recording element; nothing here depends on layout, only on what the
@@ -268,6 +272,9 @@ beforeEach(() => {
     state.fraudContracts = [];
     state.hideLowHolderTokens = false;
     state.currentView = null;
+    // The screens save this page's copy of "Use Blockscout" over the stored
+    // one. So the page's copy is turned on here too.
+    state.useBlockscout = true;
 });
 
 describe("the Send screen resolves the scale rather than reading the stored one", () => {