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

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

These steps drop earlier steps from the sum:

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

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

Model: opus-5-5

README.md

@@ -905,8 +905,8 @@ src/
     prices.js         — ETH/USD and token/USD from Chainlink price feeds
     scamlist.js       — known fraud contract addresses
     state.js          — persisted state (extension storage)
-    storedSettings.js — "Use Blockscout", "Check recipients on Etherscan" and
+    storedSettings.js — "Use Blockscout" and "Check recipients on Etherscan",
-                        the active network, read from storage
+                        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, and their Chainlink
                         price feeds (hardcoded)
@@ -1266,7 +1266,8 @@ see Transaction Decoding), do not always read as a number. They can read:
   the same words. `Unlimited`, `All available (V4 open delta)` and
   `Whatever an earlier step sent to the pair (V2 already paid)` keep their
   wording. When a V2 or V3 exact-out step sets `Min. received`, that line shows
-  its `amountOut`, the exact amount it buys.
+  its `amountOut`, the exact amount it buys. When earlier swap steps also pay
+  that token to the user, the line shows the sum (see Transaction Decoding).
 - `All available (V4 open delta)`: the swap's `Amount` line, when the amount it
   shows is a V4 exact-in `amountIn` of zero. V4 reads that zero as "use the
   whole open delta", so the calldata states no quantity. Transaction Decoding
@@ -3459,19 +3460,29 @@ Currently supported:
   name); and one more reads `Unknown (could not be decoded)` when a step that
   may pay an address went unread. When no step pays anyone, a single line reads
   `Unknown (not named in the calldata)`. Wherever there is a `Paid to` line, the
-  minimum reads `Min. paid out`. The `Amount` line gives the total the steps
+  minimum reads `Min. paid out`. The step that sets the output side gives the
-  take of `Token In`, from the step that sets the input side on: the first V2 or
+  minimum. When that step and earlier swap steps each pay the output token to
-  V3 exact-in or exact-out, `WRAP_ETH` or V4 swap step that names an input token
+  the transaction's sender, the minimum is the sum of their minimums. There is
-  or amount. A V4 step with a swap action sets the input side when no earlier
+  no minimum when the decoder reads none from one of them, or when one of them
-  step set it, even when it names neither (see Display Consistency). That step
+  pays part of that token elsewhere. There is also no minimum when the decoder
-  counts its own amount, whoever pays it: a V2 or V3 exact-out step its
+  did not read one of them, or a step between them, in full. A swap step that
-  `amountInMax`, and a V4 step what it takes of its input token from the user's
+  spends the output token drops earlier steps from the sum. A V4 step spends
-  wallet, as below, or, when the user pays it none of that token, the `amountIn`
+  each token that its swap actions spend. A V4 `SETTLE` or `SETTLE_ALL` of the
-  of the swap action that spends it. Each later V2 or V3 exact-in or exact-out
+  output token also drops earlier steps. A `PERMIT2_TRANSFER_FROM` of the output
-  step whose `payerIsUser` is true takes its amount, found in the same way, from
+  token drops earlier steps too. A step after the step that sets the output side
-  the user's wallet. Every V4 step, with a swap action or without, takes from
+  drops nothing from the sum. The `Amount` line gives the total the steps take
-  the user's wallet what its `SETTLE`s paid by the user (`payerIsUser` true) and
+  of `Token In`, from the step that sets the input side on: the first V2 or V3
-  its `SETTLE_ALL`s pay, for each token on its own; what the step that sets the
+  exact-in or exact-out, `WRAP_ETH` or V4 swap step that names an input token or
+  amount. A V4 step with a swap action sets the input side when no earlier step
+  set it, even when it names neither (see Display Consistency). That step counts
+  its own amount, whoever pays it: a V2 or V3 exact-out step its `amountInMax`,
+  and a V4 step what it takes of its input token from the user's wallet, as
+  below, or, when the user pays it none of that token, the `amountIn` of the
+  swap action that spends it. Each later V2 or V3 exact-in or exact-out step
+  whose `payerIsUser` is true takes its amount, found in the same way, from the
+  user's wallet. Every V4 step, with a swap action or without, takes from the
+  user's wallet what its `SETTLE`s paid by the user (`payerIsUser` true) and its
+  `SETTLE_ALL`s pay, for each token on its own; what the step that sets the
   input side takes of any other token counts as a later step's take. A `SETTLE`
   of any amount but `OPEN_DELTA` pays that amount, and a `SETTLE` of
   `OPEN_DELTA` or a `SETTLE_ALL` pays what the step owes, as above. So a V4 step

src/popup/views/addressDetail.js

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

src/popup/views/addressToken.js

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

src/popup/views/home.js

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

src/popup/views/settings.js

@@ -334,11 +334,6 @@ function showNewSettings() {
 // src/popup/index.js) between setting the URL and writing it. If the active
 // network is no longer `networkId`, on this page or in the stored record,
 // nothing is saved. The flash message then says that the network changed.
-//
-// The save writes only the fields that differ from what this page last saved.
-// Another page may have stored a different URL since then. So `url` is set in
-// the stored record too. "Saved." then means that the stored record holds
-// `url`.
 async function saveEndpoint(field, url, networkId) {
     let refused = false;
     await saveState((stored) => {
@@ -346,7 +341,6 @@ async function saveEndpoint(field, url, networkId) {
             state.networkId !== networkId || stored.networkId !== networkId;
         if (refused) return false;
         state[field] = url;
-        stored[field] = url;
     });
     if (refused) {
         showFlash("The URL was not saved because the network changed.");

src/shared/storedSettings.js

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

src/shared/uniswap.js

@@ -988,6 +988,9 @@ function totalAmount(amounts) {
 // pays it of Token In as the step's amount in place of the rules' Amount, or
 // no amount when this decoder cannot tell what that is.
 //
+// `spent` lists the currency that each swap action spends, for each swap
+// action that this decoder could read.
+//
 // `takes` is every TAKE, TAKE_ALL and TAKE_PORTION, as the currency it takes
 // and its recipient as written, MSG_SENDER for a TAKE_ALL. TAKE_PORTION takes
 // a share of the currency, so it does not name the output side as TAKE does.
@@ -1163,6 +1166,8 @@ function decodeV4Swap(input) {
             }
         }
 
+        const spent = swaps.map((s) => s.tokenIn);
+
         // Rule 3.
         if (swapUndecoded) {
             return {
@@ -1170,6 +1175,7 @@ function decodeV4Swap(input) {
                 tokenOut: takeToken,
                 amountIn: null,
                 amountOutMin: null,
+                spent,
                 takes,
                 settledFromRouter,
                 paidByUser,
@@ -1180,7 +1186,6 @@ function decodeV4Swap(input) {
             };
         }
 
-        const spent = swaps.map((s) => s.tokenIn);
         const bought = swaps.map((s) => s.tokenOut);
 
         // Rules 1 and 2 for Token In.
@@ -1216,6 +1221,7 @@ function decodeV4Swap(input) {
             tokenOut,
             amountIn,
             amountOutMin,
+            spent,
             takes,
             settledFromRouter,
             paidByUser,
@@ -1307,8 +1313,9 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         const commandNames = [];
 
         // THE INVARIANT: an amount and the token it is counted in always come
-        // from the same hop, or from hops that all spend that token. A figure
+        // from the same hop, or from hops that all spend that token or all buy
-        // is never rendered against a token that did not supply it.
+        // it. A figure is never rendered against a token that did not supply
+        // it.
         //
         // Both sides are therefore set as a PAIR — never field by field, and
         // never on truthiness. An address is never falsy once set but an
@@ -1423,6 +1430,10 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             const r = recipient.toLowerCase();
             return r === ADDRESS_THIS || r === toAddress.toLowerCase();
         };
+        const isSender = (recipient) => {
+            const r = recipient.toLowerCase();
+            return r === MSG_SENDER || r === sender;
+        };
         // A swap step or V4 SETTLE pays `amount` of `token` from the router's
         // own balance. CONTRACT_BALANCE pays all of it. Any other quantity
         // counts against the amount a WRAP_ETH stated, and the steps pay all
@@ -1455,17 +1466,73 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // A step pays `recipient`. `output` is the token a swap step or a V4
         // TAKE or TAKE_PORTION pays; other steps pass none.
         const addPayee = (recipient, output) => {
-            const r = recipient.toLowerCase();
             if (isRouter(recipient)) {
                 if (present(output)) {
                     heldByRouter.set(output.toLowerCase(), null);
                 }
-            } else if (r === MSG_SENDER || r === sender) {
+            } else if (isSender(recipient)) {
                 paidToSender = true;
             } else {
                 addPaidElsewhere(recipient);
             }
         };
+        // Each swap step that paid the sender some of the token it bought,
+        // as { step, token, amount, onlyToSender }:
+        // - `step` is the step's index;
+        // - `token` is that token;
+        // - `amount` is the step's stated minimum;
+        // - `onlyToSender` is whether the step paid all of that token to the
+        //   sender.
+        // A later step that spends that token takes the step off this list
+        // (see dropFromSum()).
+        let swapsPayingSender = [];
+        // The step being read spends `token`, so it may spend what an earlier
+        // swap step paid the sender. Each step on swapsPayingSender that
+        // bought `token` leaves the list. A step spends a token as follows:
+        // - a V2 or V3 swap step spends its input token;
+        // - a V4 step spends each token that one of its swap actions spends,
+        //   and each token that one of its SETTLEs or SETTLE_ALLs pays;
+        // - a PERMIT2_TRANSFER_FROM spends the token it moves.
+        const dropFromSum = (token) => {
+            swapsPayingSender = swapsPayingSender.filter(
+                (s) => !sameAddress(s.token, token),
+            );
+        };
+        // The minimum the output side shows for the swap step at `step`. The
+        // step buys `token` with the stated minimum `amount`, and pays
+        // `token` to `recipients`. The minimum is the step's own, unless this
+        // step and an earlier one on swapsPayingSender both pay `token` to
+        // the sender, as a route split across steps does. The minimum is then
+        // the total of all such steps' minimums. There is none when this
+        // decoder reads no minimum from one of them, or when one of them pays
+        // some of `token` elsewhere. There is also none when this decoder did
+        // not read one of them, or a step between them, in full (see
+        // stepsUnread).
+        const swapMinimum = (step, token, amount, recipients) => {
+            const toSender = recipients.filter(
+                (r) => present(r) && isSender(r),
+            );
+            if (toSender.length === 0) return amount;
+            swapsPayingSender.push({
+                step,
+                token,
+                amount,
+                onlyToSender: toSender.length === recipients.length,
+            });
+            const split = swapsPayingSender.filter((s) =>
+                sameAddress(s.token, token),
+            );
+            if (split.length < 2) return amount;
+            if (
+                split.some(
+                    (s) => !s.onlyToSender || typeof s.amount !== "bigint",
+                ) ||
+                stepsUnread.some((unread) => unread >= split[0].step)
+            ) {
+                return null;
+            }
+            return split.reduce((sum, s) => sum + s.amount, 0n);
+        };
         // A step that pays `token` to `recipient` is a hop, not a payout,
         // when the very next step is a V2 exact-in whose input is already
         // paid, whose path starts at `token`, and whose pair (see v2PairFor())
@@ -1607,6 +1674,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                                     : null,
                         });
                     }
+                    if (p) dropFromSum(p.token);
                 } else if (command === "BALANCE_CHECK_ERC20") {
                     const b = decodeBalanceCheck(inputs[i]);
                     if (!b) {
@@ -1649,10 +1717,18 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         } else if (s.payerIsUser) {
                             addUserPaid(s.tokenIn, s.amountIn);
                         }
+                        dropFromSum(s.tokenIn);
                         // Always update output: in multi-step swaps (V3 → V4),
-                        // the last swap step determines the final output token
+                        // the last swap step determines the final output
-                        // and minimum received amount.
+                        // token. swapMinimum() gives the minimum.
-                        setOutput(i, s.tokenOut, s.amountOutMin, [s.recipient]);
+                        setOutput(
+                            i,
+                            s.tokenOut,
+                            swapMinimum(i, s.tokenOut, s.amountOutMin, [
+                                s.recipient,
+                            ]),
+                            [s.recipient],
+                        );
                         if (!s.payerIsUser) {
                             spendFromRouter(s.tokenIn, s.amountIn);
                         }
@@ -1673,7 +1749,15 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         } else if (s.payerIsUser) {
                             addUserPaid(s.tokenIn, s.amountIn);
                         }
-                        setOutput(i, s.tokenOut, s.amountOutMin, [s.recipient]);
+                        dropFromSum(s.tokenIn);
+                        setOutput(
+                            i,
+                            s.tokenOut,
+                            swapMinimum(i, s.tokenOut, s.amountOutMin, [
+                                s.recipient,
+                            ]),
+                            [s.recipient],
+                        );
                         if (!s.payerIsUser) {
                             spendFromRouter(s.tokenIn, s.amountIn);
                         }
@@ -1705,7 +1789,15 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         } else if (s.payerIsUser) {
                             addUserPaid(s.tokenIn, s.amountInMax);
                         }
-                        setOutput(i, s.tokenOut, s.amountOut, [s.recipient]);
+                        dropFromSum(s.tokenIn);
+                        setOutput(
+                            i,
+                            s.tokenOut,
+                            swapMinimum(i, s.tokenOut, s.amountOut, [
+                                s.recipient,
+                            ]),
+                            [s.recipient],
+                        );
                         if (!isHop(i, s.tokenOut, s.recipient)) {
                             addPayee(s.recipient, s.tokenOut);
                         }
@@ -1877,6 +1969,11 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                                 addPayee(t.recipient, t.currency);
                             }
                         }
+                        for (const token of v4.spent) dropFromSum(token);
+                        for (const s of v4.paidByUser) dropFromSum(s.currency);
+                        for (const s of v4.settledFromRouter) {
+                            dropFromSum(s.currency);
+                        }
                     }
                     if (!v4 || v4.recipientUnread) {
                         payeeUnread = true;
@@ -1925,7 +2022,12 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                             setInput(v4.tokenIn, amountIn);
                         }
                         outputToken = v4.tokenOut;
-                        minOutput = v4.amountOutMin;
+                        minOutput = swapMinimum(
+                            i,
+                            v4.tokenOut,
+                            v4.amountOutMin,
+                            takeRecipients,
+                        );
                         outputEstablished = true;
                         outputUnwrapped = false;
                         unwrapIntoRouterStep = null;

tests/historyAfterNetworkSwitch.test.js

@@ -1,493 +0,0 @@
-// Home, AddressDetail and AddressToken drop a transaction history answer that
-// lands after a network switch. A dropped answer draws no rows and saves no
-// fraud contracts (https://git.eeqj.de/sneak/AutistMask/issues/657).
-//
-// Most tests hold the history request open, switch the network or what the
-// screen shows, and then let the answer land. The views run against a minimal
-// DOM stub, as in tests/transactionListCancelled.test.js, and over
-// tests/support/storageStub.js.
-
-const { makeStorageStub } = require("./support/storageStub");
-const { STATE_SCHEMA_VERSION } = require("../src/shared/stateSchema");
-
-jest.mock("../src/shared/transactions", () => ({
-    ...jest.requireActual("../src/shared/transactions"),
-    fetchRecentTransactions: jest.fn(async () => []),
-}));
-jest.mock("../src/shared/ens", () => ({
-    resolveEnsNames: jest.fn(async () => new Map()),
-}));
-
-const { fetchRecentTransactions } = require("../src/shared/transactions");
-const { resolveEnsNames } = require("../src/shared/ens");
-const { state, loadState } = require("../src/shared/state");
-const { onChainSwitch } = require("../src/shared/chainSwitch");
-const { applyChainSwitchFields } = require("../src/shared/chainSwitchFields");
-const { storedNetworkIs } = require("../src/shared/storedSettings");
-const home = require("../src/popup/views/home");
-const addressDetail = require("../src/popup/views/addressDetail");
-const addressToken = require("../src/popup/views/addressToken");
-
-const ADDRESS = "0x1111111111111111111111111111111111111111";
-const OTHER_ADDRESS = "0x2222222222222222222222222222222222222222";
-const RECIPIENT = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
-// A contract that sends a token claiming USDT's symbol. Spotting the spoof
-// adds this contract to the fraud contracts.
-const SPOOF_CONTRACT = "0x3333333333333333333333333333333333333333";
-const TOKEN = "0x6B175474E89094C44Da98b954EedeAC495271d0F";
-
-// A profile on Ethereum Mainnet with two addresses, "Use Blockscout" on and no
-// fraud contracts.
-function profile() {
-    return {
-        schemaVersion: STATE_SCHEMA_VERSION,
-        hasWallet: true,
-        wallets: [
-            {
-                type: "hd",
-                name: "Main",
-                xpub: "xpub-main",
-                encryptedSecret: "encrypted-secret",
-                nextIndex: 2,
-                addresses: [
-                    { address: ADDRESS, balance: "1.0", tokenBalances: [] },
-                    {
-                        address: OTHER_ADDRESS,
-                        balance: "0.0",
-                        tokenBalances: [],
-                    },
-                ],
-            },
-        ],
-        activeAddress: ADDRESS,
-        networkId: "mainnet",
-        rpcUrl: "https://ethereum-rpc.publicnode.com",
-        blockscoutUrl: "https://eth.blockscout.com/api/v2",
-        useBlockscout: true,
-        fraudContracts: [],
-    };
-}
-
-// What Blockscout answers for ADDRESS on Ethereum Mainnet:
-//
-// - a transfer of ETH from ADDRESS;
-// - a transfer of the fake USDT from SPOOF_CONTRACT.
-function history() {
-    return [
-        {
-            hash: "0x85215772ed26ea8b39c2b3b18779030487efbe0b5fd7e882592b2f62b837be84",
-            blockNumber: 2,
-            from: ADDRESS,
-            to: RECIPIENT,
-            value: "1.0000",
-            exactValue: "1.0",
-            rawAmount: "1000000000000000000",
-            rawUnit: "wei",
-            symbol: "ETH",
-            timestamp: 1790000000,
-            isError: false,
-            directionLabel: "Sent",
-            direction: "sent",
-            contractAddress: null,
-        },
-        {
-            hash: "0x0d6a6e0a0d1b7d4c3b2a19087f6e5d4c3b2a19087f6e5d4c3b2a19087f6e5d4c",
-            blockNumber: 1,
-            from: SPOOF_CONTRACT,
-            to: ADDRESS,
-            value: "100.0000",
-            exactValue: "100.0",
-            rawAmount: "100000000",
-            rawUnit: "base units",
-            symbol: "USDT",
-            timestamp: 1790000000,
-            isError: false,
-            directionLabel: "Received",
-            direction: "received",
-            contractAddress: SPOOF_CONTRACT,
-        },
-    ];
-}
-
-// The next history request waits until the returned function is called, and
-// then answers with `answer`.
-function holdHistory(answer = history()) {
-    let land;
-    fetchRecentTransactions.mockImplementationOnce(
-        () =>
-            new Promise((resolve) => {
-                land = () => resolve(answer);
-            }),
-    );
-    return () => land();
-}
-
-// The next history request waits until the returned function is called, and
-// then fails.
-function holdFailure() {
-    let fail;
-    fetchRecentTransactions.mockImplementationOnce(
-        () =>
-            new Promise((resolve, reject) => {
-                fail = () => reject(new Error("Blockscout is down"));
-            }),
-    );
-    return () => fail();
-}
-
-// Another write holds the lock until the returned function is called. Every
-// save waits until then.
-function holdLock() {
-    let release;
-    const held = navigator.locks.request(
-        "autistmask",
-        () =>
-            new Promise((resolve) => {
-                release = resolve;
-            }),
-    );
-    return async () => {
-        release();
-        await held;
-    };
-}
-
-function makeElement(id) {
-    const el = {
-        id,
-        textContent: "",
-        value: "",
-        innerHTML: "",
-        style: {},
-        dataset: {},
-        classList: {
-            add: () => {},
-            remove: () => {},
-            contains: () => false,
-            toggle: () => false,
-        },
-        addEventListener: () => {},
-        querySelectorAll: () => [],
-        appendChild: () => {},
-    };
-    // Views reach for .parentElement to hide whole sections.
-    Object.defineProperty(el, "parentElement", {
-        get: () => node(id + "-parent"),
-    });
-    return el;
-}
-
-function makeDocument() {
-    const els = new Map();
-    return {
-        getElementById(id) {
-            // The debug banner is created on demand by helpers.js; absent
-            // is the state a non-debug, non-testnet popup is in.
-            if (id === "debug-banner") return null;
-            if (!els.has(id)) els.set(id, makeElement(id));
-            return els.get(id);
-        },
-        createElement: () => makeElement("created"),
-        addEventListener: () => {},
-        body: { prepend: () => {} },
-    };
-}
-
-function node(id) {
-    return globalThis.document.getElementById(id);
-}
-
-// Lets every promise that is not held open settle.
-function settle() {
-    return new Promise((resolve) => setTimeout(resolve, 0));
-}
-
-let storage;
-
-beforeEach(async () => {
-    storage = makeStorageStub({ autistmask: profile() });
-    globalThis.chrome = {
-        storage: { local: storage.local, onChanged: storage.onChanged },
-    };
-    globalThis.document = makeDocument();
-    globalThis.window = { location: { search: "" } };
-    await loadState();
-    state.viewStack = [];
-    state.selectedWallet = 0;
-    state.selectedAddress = 0;
-    state.selectedToken = "ETH";
-    const ctx = { pageClosed: new AbortController().signal };
-    addressDetail.init(ctx);
-    addressToken.init(ctx);
-});
-
-afterEach(() => {
-    delete globalThis.chrome;
-    delete globalThis.document;
-    delete globalThis.window;
-});
-
-const HOME = {
-    name: "Home",
-    listId: "home-tx-list",
-    open: () => home.render({ pageClosed: new AbortController().signal }),
-};
-const ADDRESS_DETAIL = {
-    name: "AddressDetail",
-    listId: "tx-list",
-    open: () => addressDetail.show(),
-};
-const ADDRESS_TOKEN = {
-    name: "AddressToken",
-    listId: "address-token-tx-list",
-    open: () => addressToken.show(),
-};
-
-// Three ways a test switches the network:
-//
-// - made in Settings: the page and storage have both switched;
-// - saved elsewhere: storage has switched and the page has not;
-// - not yet stored: the page has switched and storage has not.
-const SWITCHES = [
-    {
-        how: "made in Settings",
-        to: (networkId) => onChainSwitch(networkId),
-    },
-    {
-        // Another page or the background stored the switch, and this page has
-        // not followed it yet.
-        how: "saved elsewhere",
-        to: async (networkId) => {
-            const record = storage.read("autistmask");
-            applyChainSwitchFields(record, networkId);
-            storage.write("autistmask", record);
-        },
-    },
-    {
-        // The switch's own save has changed the page and has not yet written
-        // storage.
-        how: "not yet stored",
-        to: async (networkId) => {
-            applyChainSwitchFields(state, networkId);
-        },
-    },
-];
-
-// The list still shows `before`, and neither the page nor storage holds a
-// fraud contract.
-function expectNothingAdded(screen, before) {
-    expect(node(screen.listId).innerHTML).toBe(before);
-    expect(state.fraudContracts).toEqual([]);
-    expect(storage.read("autistmask").fraudContracts).toEqual([]);
-}
-
-describe.each([HOME, ADDRESS_DETAIL, ADDRESS_TOKEN])("$name", (screen) => {
-    test("an answer that lands on the same network is drawn and saved", async () => {
-        const land = holdHistory();
-        screen.open();
-        land();
-        await settle();
-
-        expect(node(screen.listId).innerHTML).toContain("tx-row");
-        expect(state.fraudContracts).toEqual([SPOOF_CONTRACT]);
-        expect(storage.read("autistmask").fraudContracts).toEqual([
-            SPOOF_CONTRACT,
-        ]);
-    });
-
-    test.each(SWITCHES)(
-        "an answer that lands after a switch $how adds nothing",
-        async ({ to }) => {
-            const land = holdHistory();
-            screen.open();
-            await settle();
-            const before = node(screen.listId).innerHTML;
-            await to("sepolia");
-            land();
-            await settle();
-
-            expectNothingAdded(screen, before);
-        },
-    );
-
-    // The answer is the transfer of ETH alone, which adds no fraud contract.
-    // Nothing is saved, so only the check before the save can drop the answer.
-    test.each(SWITCHES)(
-        "an answer without a fraud contract that lands after a switch $how adds nothing",
-        async ({ to }) => {
-            const land = holdHistory(history().slice(0, 1));
-            screen.open();
-            await settle();
-            const before = node(screen.listId).innerHTML;
-            await to("sepolia");
-            land();
-            await settle();
-
-            expectNothingAdded(screen, before);
-        },
-    );
-
-    test.each(SWITCHES)(
-        "a request that fails after a switch $how shows no message",
-        async ({ to }) => {
-            const fail = holdFailure();
-            screen.open();
-            await settle();
-            const before = node(screen.listId).innerHTML;
-            await to("sepolia");
-            fail();
-            await settle();
-
-            expect(node(screen.listId).innerHTML).toBe(before);
-        },
-    );
-
-    // The user picks Sepolia in Settings while another write holds the lock.
-    // The answer lands, and its save waits behind the switch.
-    test("an answer whose save waits behind a switch made in Settings adds nothing", async () => {
-        const land = holdHistory();
-        screen.open();
-        const before = node(screen.listId).innerHTML;
-        const releaseLock = holdLock();
-        const switching = onChainSwitch("sepolia");
-        land();
-        await settle();
-        await releaseLock();
-        await switching;
-        await settle();
-
-        expectNothingAdded(screen, before);
-    });
-
-    // The answer lands and its save waits for the lock. Another page or the
-    // background then stores a switch.
-    test("an answer whose save waits while a switch is saved elsewhere adds nothing", async () => {
-        const land = holdHistory();
-        screen.open();
-        const before = node(screen.listId).innerHTML;
-        const releaseLock = holdLock();
-        land();
-        await settle();
-        const record = storage.read("autistmask");
-        applyChainSwitchFields(record, "sepolia");
-        storage.write("autistmask", record);
-        await releaseLock();
-        await settle();
-
-        expectNothingAdded(screen, before);
-    });
-
-    // The answer lands and its save waits for the lock. The page then switches,
-    // and storage has not.
-    test("an answer whose save waits while the page switches adds nothing", async () => {
-        const land = holdHistory();
-        screen.open();
-        const before = node(screen.listId).innerHTML;
-        const releaseLock = holdLock();
-        land();
-        await settle();
-        applyChainSwitchFields(state, "sepolia");
-        await releaseLock();
-        await settle();
-
-        expectNothingAdded(screen, before);
-    });
-
-    test("a request that fails after a switch leaves the new network's rows", async () => {
-        const fail = holdFailure();
-        screen.open();
-        await onChainSwitch("sepolia");
-        fetchRecentTransactions.mockImplementationOnce(async () => history());
-        screen.open();
-        await settle();
-        const drawn = node(screen.listId).innerHTML;
-        fail();
-        await settle();
-
-        expect(drawn).toContain("tx-row");
-        expect(node(screen.listId).innerHTML).toBe(drawn);
-    });
-});
-
-describe.each([ADDRESS_DETAIL, ADDRESS_TOKEN])("$name", (screen) => {
-    test("an answer that lands once the screen shows another address adds nothing", async () => {
-        const land = holdHistory();
-        screen.open();
-        state.selectedAddress = 1;
-        screen.open();
-        await settle();
-        const before = node(screen.listId).innerHTML;
-        land();
-        await settle();
-
-        expectNothingAdded(screen, before);
-    });
-
-    test("a request that fails once the screen shows another address shows no message", async () => {
-        const fail = holdFailure();
-        screen.open();
-        state.selectedAddress = 1;
-        screen.open();
-        await settle();
-        const before = node(screen.listId).innerHTML;
-        fail();
-        await settle();
-
-        expect(node(screen.listId).innerHTML).toBe(before);
-    });
-
-    test("an answer whose name lookup lands after a switch adds nothing", async () => {
-        let landNames;
-        resolveEnsNames.mockImplementationOnce(
-            () =>
-                new Promise((resolve) => {
-                    landNames = () => resolve(new Map());
-                }),
-        );
-        fetchRecentTransactions.mockImplementationOnce(async () => history());
-        screen.open();
-        await settle();
-        const before = node(screen.listId).innerHTML;
-        await onChainSwitch("sepolia");
-        landNames();
-        await settle();
-
-        expectNothingAdded(screen, before);
-    });
-});
-
-test("AddressToken: an answer that lands once the screen shows another token adds nothing", async () => {
-    const land = holdHistory();
-    addressToken.show();
-    state.selectedToken = TOKEN;
-    addressToken.show();
-    await settle();
-    const before = node(ADDRESS_TOKEN.listId).innerHTML;
-    land();
-    await settle();
-
-    expectNothingAdded(ADDRESS_TOKEN, before);
-});
-
-test("AddressToken: a request that fails once the screen shows another token shows no message", async () => {
-    const fail = holdFailure();
-    addressToken.show();
-    state.selectedToken = TOKEN;
-    addressToken.show();
-    await settle();
-    const before = node(ADDRESS_TOKEN.listId).innerHTML;
-    fail();
-    await settle();
-
-    expect(node(ADDRESS_TOKEN.listId).innerHTML).toBe(before);
-});
-
-test("storedNetworkIs(): a failed read counts as no", async () => {
-    globalThis.chrome.storage.local = {
-        get: async () => {
-            throw new Error("storage is down");
-        },
-    };
-
-    await expect(storedNetworkIs("mainnet")).resolves.toBe(false);
-});

tests/settingsEndpointSave.test.js

@@ -1,49 +0,0 @@
-// Another page stores a different RPC or Blockscout URL for the same network.
-// Then the user taps "Save" in Settings on this page, on the URL that this page
-// loaded. The URL on screen is stored, and the flash message reads "Saved."
-// (https://git.eeqj.de/sneak/AutistMask/issues/688). Driven through the real
-// popup over a stored profile on Ethereum Mainnet.
-
-const {
-    bootPopup,
-    cleanupPopup,
-    unversionedValidProfile,
-} = require("./support/popupBoot");
-const { NETWORKS } = require("../src/shared/networks");
-
-afterEach(() => {
-    cleanupPopup();
-});
-
-test.each([
-    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
-    {
-        button: "btn-save-blockscout",
-        input: "settings-blockscout",
-        field: "blockscoutUrl",
-    },
-])(
-    "$button stores the URL on screen after another page stored a different one",
-    async ({ button, input, field }) => {
-        const page = await bootPopup(unversionedValidProfile());
-        await page.click("btn-settings");
-        const url = page.value(input);
-        // This write sends this page no storage change event.
-        page.storage.write("autistmask", {
-            ...page.storage.read("autistmask"),
-            [field]: "https://other-page.example.invalid",
-        });
-        // This answer passes both endpoint checks on Ethereum Mainnet. The RPC
-        // check reads Ethereum Mainnet's chain id from it. The Blockscout check
-        // reads `ok`.
-        globalThis.fetch.mockResolvedValue({
-            ok: true,
-            json: async () => ({ result: NETWORKS.mainnet.chainId }),
-        });
-
-        await page.click(button);
-
-        expect(page.storage.read("autistmask")[field]).toBe(url);
-        expect(page.text("flash-msg")).toBe("Saved.");
-    },
-);

tests/uniswap.test.js

@@ -2871,8 +2871,9 @@ describe("uniswap decoder", () => {
                         ...USDT_400_GROUP,
                         ...ONE_USDT_LINES(OTHER_ADDR),
                     ],
-                    // The last swap step's minimum.
+                    // Both swap steps pay USDC to the user, so the minimum
-                    minimum: "390.0000 USDC",
+                    // is the sum of their two minimums.
+                    minimum: "980.0000 USDC",
                 },
             ])(
                 "$kind shows each take's own lines and the allowances, and no Amount figure or Min. received",
@@ -3638,6 +3639,355 @@ describe("uniswap decoder", () => {
                 ]);
             });
         });
+
+        // https://git.eeqj.de/sneak/AutistMask/issues/647 — on next at
+        // f550d8c, a split whose steps each pay WETH to the user showed only
+        // the last step's minimum.
+        describe("the minimum of a split that pays WETH to the user", () => {
+            const WETH_01 = 100000000000000000n;
+            const WETH_02 = 200000000000000000n;
+            const WETH_03 = 300000000000000000n;
+            // A V3 exact-in of 600 USDT for at least 0.3 WETH, and a V2
+            // exact-in of 400 USDT for at least 0.2 WETH, each paid to the
+            // user.
+            const V3_TO_WETH = encodeV3SwapExactIn(
+                USER_ADDR,
+                USDT_600,
+                WETH_03,
+                [USDT_ADDR, WETH_ADDR],
+            );
+            const V2_TO_WETH = encodeV2SwapExactIn(
+                USER_ADDR,
+                USDT_400,
+                WETH_02,
+                [USDT_ADDR, WETH_ADDR],
+            );
+            // A V4 step that swaps 400 USDT for at least 0.2 WETH, with these
+            // TAKEs of the WETH.
+            const v4ToWeth = (...takes) =>
+                encodeV4Swap(
+                    new Uint8Array([
+                        V4_SWAP_EXACT_IN_SINGLE_ID,
+                        V4_SETTLE_ID,
+                        ...takes.map(() => V4_TAKE_ID),
+                    ]),
+                    [
+                        encodeV4ExactInSingle(
+                            USDT_ADDR,
+                            WETH_ADDR,
+                            USDT_400,
+                            WETH_02,
+                        ),
+                        encodeV4Settle(USDT_ADDR), // paid by the user
+                        ...takes,
+                    ],
+                );
+            // The swap's minimum line as [label, value], or undefined.
+            const minimum = (result) =>
+                result.details
+                    .filter(
+                        (d) =>
+                            d.label === "Min. received" ||
+                            d.label === "Min. paid out",
+                    )
+                    .map((d) => [d.label, d.value])[0];
+
+            test("a V3 and a V2 exact-in show the total of their minimums", () => {
+                const result = decodeSteps(
+                    [0x00, 0x08],
+                    [V3_TO_WETH, V2_TO_WETH],
+                );
+                expect(minimum(result)).toEqual([
+                    "Min. received",
+                    "0.5000 WETH",
+                ]);
+            });
+
+            test("a V3 exact-in and a V4 step show the total of their minimums", () => {
+                const result = decodeSteps(
+                    [0x00, 0x10],
+                    [V3_TO_WETH, v4ToWeth(encodeV4Take(WETH_ADDR))],
+                );
+                expect(minimum(result)).toEqual([
+                    "Min. received",
+                    "0.5000 WETH",
+                ]);
+            });
+
+            // The second route buys DAI for the router, then swaps all of it
+            // from the router for at least 0.2 WETH.
+            test("a route that hops through DAI counts its last hop's minimum", () => {
+                const result = decodeSteps(
+                    [0x00, 0x08, 0x00],
+                    [
+                        V3_TO_WETH,
+                        encodeV2SwapExactIn(ROUTER_ADDR, USDT_400, DAI_400, [
+                            USDT_ADDR,
+                            DAI_ADDR,
+                        ]),
+                        coder.encode(
+                            ["address", "uint256", "uint256", "bytes", "bool"],
+                            [
+                                USER_ADDR,
+                                2n ** 255n, // CONTRACT_BALANCE
+                                WETH_02,
+                                encodeV3Path([DAI_ADDR, WETH_ADDR]),
+                                false, // paid from the router
+                            ],
+                        ),
+                    ],
+                );
+                expect(minimum(result)).toEqual([
+                    "Min. received",
+                    "0.5000 WETH",
+                ]);
+            });
+
+            // The middle step swaps 0.3 of the user's WETH for USDC, so the
+            // sum of minimums starts again after it.
+            test.each([
+                {
+                    kind: "a V3 exact-in",
+                    command: 0x00,
+                    input: encodeV3SwapExactIn(USER_ADDR, WETH_03, 1n, [
+                        WETH_ADDR,
+                        USDC_ADDR,
+                    ]),
+                },
+                {
+                    kind: "a V2 exact-in",
+                    command: 0x08,
+                    input: encodeV2SwapExactIn(USER_ADDR, WETH_03, 1n, [
+                        WETH_ADDR,
+                        USDC_ADDR,
+                    ]),
+                },
+                {
+                    kind: "a V2 exact-out",
+                    command: 0x09,
+                    input: encodeV2SwapExactOut(USER_ADDR, 1n, WETH_03, [
+                        WETH_ADDR,
+                        USDC_ADDR,
+                    ]),
+                },
+                {
+                    kind: "a V3 exact-out",
+                    command: 0x01,
+                    input: encodeV3SwapExactOut(USER_ADDR, 1n, WETH_03, [
+                        USDC_ADDR,
+                        WETH_ADDR,
+                    ]),
+                },
+            ])(
+                "$kind that spends WETH between them leaves the last step's minimum",
+                ({ command, input }) => {
+                    const result = decodeSteps(
+                        [0x00, command, 0x08],
+                        [V3_TO_WETH, input, V2_TO_WETH],
+                    );
+                    expect(minimum(result)).toEqual([
+                        "Min. received",
+                        "0.2000 WETH",
+                    ]);
+                },
+            );
+
+            // The middle step swaps 0.3 WETH and 400 DAI for USDC, both paid
+            // by the user. It spends WETH whichever SETTLE comes last.
+            test.each([
+                { order: "WETH first", settled: [WETH_ADDR, DAI_ADDR] },
+                { order: "DAI first", settled: [DAI_ADDR, WETH_ADDR] },
+            ])(
+                "a V4 step that spends WETH and DAI between them leaves the last step's minimum, with the SETTLE of $order",
+                ({ settled }) => {
+                    const wethAndDaiForUsdc = encodeV4Swap(
+                        new Uint8Array([
+                            V4_SWAP_EXACT_IN_SINGLE_ID,
+                            V4_SWAP_EXACT_IN_SINGLE_ID,
+                            V4_SETTLE_ID,
+                            V4_SETTLE_ID,
+                            V4_TAKE_ALL_ID,
+                        ]),
+                        [
+                            encodeV4ExactInSingle(
+                                WETH_ADDR,
+                                USDC_ADDR,
+                                WETH_03,
+                                1n,
+                            ),
+                            encodeV4ExactInSingle(
+                                DAI_ADDR,
+                                USDC_ADDR,
+                                DAI_400,
+                                1n,
+                            ),
+                            ...settled.map((token) => encodeV4Settle(token)),
+                            encodeV4TakeAll(USDC_ADDR, 0n),
+                        ],
+                    );
+                    const result = decodeSteps(
+                        [0x00, 0x10, 0x08],
+                        [V3_TO_WETH, wethAndDaiForUsdc, V2_TO_WETH],
+                    );
+                    expect(minimum(result)).toEqual([
+                        "Min. received",
+                        "0.2000 WETH",
+                    ]);
+                },
+            );
+
+            // The middle step's swap actions buy WETH with the user's USDT,
+            // then swap all of that WETH for USDC.
+            test("a V4 step that swaps through WETH between them leaves the last step's minimum", () => {
+                const usdtToUsdcThroughWeth = encodeV4Swap(
+                    new Uint8Array([
+                        V4_SWAP_EXACT_IN_SINGLE_ID,
+                        V4_SWAP_EXACT_IN_SINGLE_ID,
+                        V4_SETTLE_ID,
+                        V4_TAKE_ALL_ID,
+                    ]),
+                    [
+                        encodeV4ExactInSingle(
+                            USDT_ADDR,
+                            WETH_ADDR,
+                            USDT_400,
+                            WETH_01,
+                        ),
+                        encodeV4ExactInSingle(WETH_ADDR, USDC_ADDR, 0n, 1n),
+                        encodeV4Settle(USDT_ADDR), // paid by the user
+                        encodeV4TakeAll(USDC_ADDR, 0n),
+                    ],
+                );
+                const result = decodeSteps(
+                    [0x00, 0x10, 0x08],
+                    [V3_TO_WETH, usdtToUsdcThroughWeth, V2_TO_WETH],
+                );
+                expect(minimum(result)).toEqual([
+                    "Min. received",
+                    "0.2000 WETH",
+                ]);
+            });
+
+            // The middle step has no swap action. Its SETTLE or SETTLE_ALL
+            // pays 0.3 WETH, and its TAKE pays that WETH to another address.
+            test.each([
+                {
+                    payment: "a SETTLE of WETH paid by the user",
+                    actions: [V4_SETTLE_ID, V4_TAKE_ID],
+                    params: [
+                        settle(WETH_ADDR, WETH_03, true),
+                        take(WETH_ADDR, OTHER_ADDR, 0n),
+                    ],
+                },
+                {
+                    payment: "a SETTLE of WETH paid from the router",
+                    actions: [V4_SETTLE_ID, V4_TAKE_ID],
+                    params: [
+                        settle(WETH_ADDR, WETH_03, false),
+                        take(WETH_ADDR, OTHER_ADDR, 0n),
+                    ],
+                },
+                {
+                    payment: "a SETTLE_ALL of WETH",
+                    actions: [V4_TAKE_ID, V4_SETTLE_ALL_ID],
+                    params: [
+                        take(WETH_ADDR, OTHER_ADDR, WETH_03),
+                        encodeV4SettleAll(WETH_ADDR, WETH_03),
+                    ],
+                },
+            ])(
+                "a V4 step with $payment between them leaves the last step's minimum",
+                ({ actions, params }) => {
+                    const wethToOther = encodeV4Swap(
+                        new Uint8Array(actions),
+                        params,
+                    );
+                    const result = decodeSteps(
+                        [0x00, 0x10, 0x08],
+                        [V3_TO_WETH, wethToOther, V2_TO_WETH],
+                    );
+                    expect(minimum(result)).toEqual([
+                        "Min. paid out",
+                        "0.2000 WETH",
+                    ]);
+                },
+            );
+
+            test("a PERMIT2_TRANSFER_FROM of WETH between them leaves the last step's minimum", () => {
+                const result = decodeSteps(
+                    [0x00, 0x02, 0x08],
+                    [
+                        V3_TO_WETH,
+                        permit2TransferFrom(WETH_ADDR, OTHER_ADDR, WETH_03),
+                        V2_TO_WETH,
+                    ],
+                );
+                expect(minimum(result)).toEqual([
+                    "Min. paid out",
+                    "0.2000 WETH",
+                ]);
+            });
+
+            // The decoder reads no minimum from a V4 exact-out action.
+            test("a step that states no minimum leaves no figure", () => {
+                const exactOut = encodeV4Swap(
+                    new Uint8Array([
+                        V4_SWAP_EXACT_OUT_SINGLE_ID,
+                        V4_SETTLE_ALL_ID,
+                        V4_TAKE_ALL_ID,
+                    ]),
+                    [
+                        encodeV4ExactOutSingle(
+                            USDT_ADDR,
+                            WETH_ADDR,
+                            WETH_02,
+                            USDT_400,
+                        ),
+                        encodeV4SettleAll(USDT_ADDR, USDT_400),
+                        encodeV4TakeAll(WETH_ADDR, 0n),
+                    ],
+                );
+                const result = decodeSteps(
+                    [0x10, 0x00],
+                    [exactOut, V3_TO_WETH],
+                );
+                expect(minimum(result)).toBeUndefined();
+            });
+
+            test("a step that pays some of its WETH to the router leaves no figure", () => {
+                const result = decodeSteps(
+                    [0x00, 0x10],
+                    [
+                        V3_TO_WETH,
+                        v4ToWeth(
+                            take(WETH_ADDR, USER_ADDR, WETH_01),
+                            take(WETH_ADDR, ROUTER_ADDR, 0n),
+                        ),
+                    ],
+                );
+                expect(minimum(result)).toBeUndefined();
+            });
+
+            // The router still runs a swap step whose recipient cannot be
+            // read, and that step may spend the WETH the first step paid.
+            test("a step between them that cannot be read leaves no figure", () => {
+                const result = decodeSteps(
+                    [0x00, 0x00, 0x08],
+                    [
+                        V3_TO_WETH,
+                        dirtyWord(
+                            encodeV3SwapExactIn(USER_ADDR, WETH_03, 1n, [
+                                WETH_ADDR,
+                                USDC_ADDR,
+                            ]),
+                            0,
+                        ),
+                        V2_TO_WETH,
+                    ],
+                );
+                expect(minimum(result)).toBeUndefined();
+            });
+        });
     });
 
     // https://git.eeqj.de/sneak/AutistMask/issues/359 — the output half, in