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

@@ -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
@@ -2279,11 +2280,6 @@ view would leave a wallet one click from deletion.
           no user data and is made whether or not "Use Blockscout" is ticked.
     - If the network changes before either "Save" stores its URL, the URL is not
       saved and a flash message says so
-    - Either "Save" stores its URL only if the input still shows that URL when
-      the endpoint answers. Otherwise a flash message says that the URL was not
-      saved
-    - If the user taps the same "Save" again before the endpoint answers, the
-      earlier tap stores nothing and shows no flash message
     - Etherscan:
         - "Check recipients on Etherscan" checkbox, unticked until the user
           ticks it
@@ -3464,19 +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/settings.js

@@ -50,11 +50,6 @@ let versionClickTimer = null;
 // not the one in `state`.
 let shownNetwork = null;
 
-// Each endpoint "Save" counts its taps here, under the field that it stores. A
-// tap stores its URL and shows a flash message only while it is the latest tap
-// of its "Save".
-const saveTaps = { rpcUrl: 0, blockscoutUrl: 0 };
-
 // One row per site origin, however many addresses it appears under, each with
 // an [x] that hands it to onRemove.
 function renderSiteList(containerId, origins, onRemove) {
@@ -339,43 +334,16 @@ 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.
-//
+async function saveEndpoint(field, url, networkId) {
-// The save writes only the fields that differ from what this page last saved.
-// Another page may have stored a different URL since then. So `url` is set in
-// the stored record too. "Saved." then means that the stored record holds
-// `url`.
-//
-// `input` is the id of the input that the user typed `url` in. When another
-// page changes the network, "Use Blockscout" or "Check recipients on
-// Etherscan", this page draws Settings again. A redraw during the endpoint
-// check puts the URL from `state` back in the input. So if the input no longer
-// shows `url`, nothing is saved. The flash message then says that the URL was
-// changed during the check. The save compares the input and sets `url` in
-// `state` in one step. So a redraw after the comparison shows `url`.
-//
-// `tap` is the number of the "Save" tap that checked `url`. If the user taps
-// the same "Save" again before this save holds the lock, nothing is stored. If
-// the user taps the same "Save" again before the write ends, no flash message
-// is shown.
-async function saveEndpoint(field, input, url, networkId, tap) {
     let refused = false;
-    let inputChanged = false;
     await saveState((stored) => {
-        if (saveTaps[field] !== tap) return false;
         refused =
             state.networkId !== networkId || stored.networkId !== networkId;
-        inputChanged = $(input).value.trim() !== url;
+        if (refused) return false;
-        if (refused || inputChanged) return false;
         state[field] = url;
-        stored[field] = url;
     });
-    if (saveTaps[field] !== tap) return;
     if (refused) {
         showFlash("The URL was not saved because the network changed.");
-    } else if (inputChanged) {
-        showFlash(
-            "The URL was not saved because it was changed during the check.",
-        );
     } else {
         showFlash("Saved.");
     }
@@ -387,8 +355,6 @@ function init(_ctx) {
     showPhrase.init();
 
     $("btn-save-rpc").addEventListener("click", async () => {
-        saveTaps.rpcUrl++;
-        const tap = saveTaps.rpcUrl;
         const url = $("settings-rpc").value.trim();
         if (!url) {
             showFlash("Please enter an RPC URL.");
@@ -409,8 +375,6 @@ function init(_ctx) {
                 }),
             });
             const json = await resp.json();
-            // The user has tapped this "Save" again since the check began.
-            if (tap !== saveTaps.rpcUrl) return;
             if (json.error) {
                 log.errorf("RPC validation error:", json.error);
                 showFlash("Endpoint returned an error.");
@@ -424,7 +388,6 @@ function init(_ctx) {
             // Cancelled by the popup closing, not failed: see pageClosed in
             // src/popup/index.js.
             if (ctx.pageClosed.aborted) return;
-            if (tap !== saveTaps.rpcUrl) return;
             // Not the error's message: fetch puts the whole URL, password and
             // key included, in the message of the error it throws for a URL
             // with a user name and password or one it cannot parse.
@@ -432,12 +395,10 @@ function init(_ctx) {
             showFlash("Could not reach endpoint.");
             return;
         }
-        await saveEndpoint("rpcUrl", "settings-rpc", url, net.id, tap);
+        await saveEndpoint("rpcUrl", url, net.id);
     });
 
     $("btn-save-blockscout").addEventListener("click", async () => {
-        saveTaps.blockscoutUrl++;
-        const tap = saveTaps.blockscoutUrl;
         const url = $("settings-blockscout").value.trim();
         if (!url) {
             showFlash("Please enter a Blockscout API URL.");
@@ -447,26 +408,18 @@ function init(_ctx) {
         showFlash("Testing endpoint...");
         try {
             const resp = await debugFetch(url + "/stats");
-            if (tap !== saveTaps.blockscoutUrl) return;
             if (!resp.ok) {
                 showFlash("Endpoint returned HTTP " + resp.status + ".");
                 return;
             }
         } catch {
             if (ctx.pageClosed.aborted) return;
-            if (tap !== saveTaps.blockscoutUrl) return;
             // Not the error's message, as for the RPC check above.
             log.errorf("Blockscout validation failed:", urlOrigin(url));
             showFlash("Could not reach endpoint.");
             return;
         }
-        await saveEndpoint(
+        await saveEndpoint("blockscoutUrl", url, net.id);
-            "blockscoutUrl",
-            "settings-blockscout",
-            url,
-            net.id,
-            tap,
-        );
     });
 
     // Each change is made inside the save, holding the lock. So

src/popup/views/transactionDetail.js

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

src/shared/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/settingsEndpointSave.test.js

@@ -1,393 +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",
-    },
-])(
-    "$button stores the URL on screen after another page stored a different one",
-    async ({ button, input, field }) => {
-        const page = await bootPopup(unversionedValidProfile());
-        await page.click("btn-settings");
-        const url = page.value(input);
-        // This write sends this page no storage change event.
-        page.storage.write("autistmask", {
-            ...page.storage.read("autistmask"),
-            [field]: "https://other-page.example.invalid",
-        });
-        // This answer passes both endpoint checks on Ethereum Mainnet. The RPC
-        // check reads Ethereum Mainnet's chain id from it. The Blockscout check
-        // reads `ok`.
-        globalThis.fetch.mockResolvedValue({
-            ok: true,
-            json: async () => ({ result: NETWORKS.mainnet.chainId }),
-        });
-
-        await page.click(button);
-
-        expect(page.storage.read("autistmask")[field]).toBe(url);
-        expect(page.text("flash-msg")).toBe("Saved.");
-    },
-);
-
-// The user types a URL in Settings and taps "Save". While the check waits for
-// the endpoint's answer, another page turns "Use Blockscout" on. This page
-// follows that change and draws Settings again, with the stored URL in the
-// input. The check then passes. The typed URL is not stored. The flash message
-// says that the URL was changed during the check
-// (https://git.eeqj.de/sneak/AutistMask/issues/695).
-test.each([
-    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
-    {
-        button: "btn-save-blockscout",
-        input: "settings-blockscout",
-        field: "blockscoutUrl",
-    },
-])(
-    "$button stores nothing when Settings is drawn again during the check",
-    async ({ button, input, field }) => {
-        const page = await bootPopup(unversionedValidProfile());
-        await page.click("btn-settings");
-        const storedUrl = page.value(input);
-        let answer;
-        globalThis.fetch.mockReturnValue(
-            new Promise((resolve) => {
-                answer = resolve;
-            }),
-        );
-
-        page.node(input).value = "https://typed.example.invalid";
-        const saving = page.node(button).listeners.click.map((fn) => fn());
-        await page.settle();
-        // The browser announces this write to this page.
-        await page.storage.local.set({
-            autistmask: {
-                ...page.storage.read("autistmask"),
-                useBlockscout: true,
-            },
-        });
-        await page.settle();
-        expect(page.node("settings-use-blockscout").checked).toBe(true);
-        // This answer passes both endpoint checks on Ethereum Mainnet.
-        answer({
-            ok: true,
-            json: async () => ({ result: NETWORKS.mainnet.chainId }),
-        });
-        await Promise.all(saving);
-        await page.settle();
-
-        expect(page.storage.read("autistmask")[field]).toBe(storedUrl);
-        expect(page.value(input)).toBe(storedUrl);
-        expect(page.text("flash-msg")).toBe(
-            "The URL was not saved because it was changed during the check.",
-        );
-    },
-);
-
-// As above, but another write holds the lock. So this page's follow of the
-// change to "Use Blockscout" waits for the lock. The endpoint answers while the
-// input still shows the typed URL. The save then asks for the lock, after the
-// follow did. So the follow draws Settings again before the save compares the
-// input.
-test.each([
-    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
-    {
-        button: "btn-save-blockscout",
-        input: "settings-blockscout",
-        field: "blockscoutUrl",
-    },
-])(
-    "$button stores nothing when Settings is drawn again while the save waits for the lock",
-    async ({ button, input, field }) => {
-        const page = await bootPopup(unversionedValidProfile());
-        await page.click("btn-settings");
-        const storedUrl = page.value(input);
-        let answer;
-        globalThis.fetch.mockReturnValue(
-            new Promise((resolve) => {
-                answer = resolve;
-            }),
-        );
-        const typedUrl = "https://typed.example.invalid";
-
-        page.node(input).value = typedUrl;
-        const saving = page.node(button).listeners.click.map((fn) => fn());
-        await page.settle();
-        let releaseLock;
-        const lockHeld = navigator.locks.request(
-            "autistmask",
-            () =>
-                new Promise((resolve) => {
-                    releaseLock = resolve;
-                }),
-        );
-        // The browser announces this write to this page.
-        await page.storage.local.set({
-            autistmask: {
-                ...page.storage.read("autistmask"),
-                useBlockscout: true,
-            },
-        });
-        await page.settle();
-        // This answer passes both endpoint checks on Ethereum Mainnet.
-        answer({
-            ok: true,
-            json: async () => ({ result: NETWORKS.mainnet.chainId }),
-        });
-        await page.settle();
-        expect(page.value(input)).toBe(typedUrl);
-        releaseLock();
-        await lockHeld;
-        await Promise.all(saving);
-        await page.settle();
-
-        expect(page.node("settings-use-blockscout").checked).toBe(true);
-        expect(page.storage.read("autistmask")[field]).toBe(storedUrl);
-        expect(page.value(input)).toBe(storedUrl);
-        expect(page.text("flash-msg")).toBe(
-            "The URL was not saved because it was changed during the check.",
-        );
-    },
-);
-
-// This answer passes both endpoint checks on Ethereum Mainnet.
-const PASSING_ANSWER = {
-    ok: true,
-    json: async () => ({ result: NETWORKS.mainnet.chainId }),
-};
-
-// Both endpoint checks read this answer as an error. The RPC check reads the
-// answer's `error`. The Blockscout check reads the answer's `ok`.
-const ERROR_ANSWER = {
-    ok: false,
-    status: 500,
-    json: async () => ({ error: { code: -32603, message: "Internal error" } }),
-};
-
-// The user types a URL in Settings and taps "Save". Before the endpoint answers,
-// the user types a second URL and taps "Save" again. The second check passes
-// first. The second URL is stored, and the flash message reads "Saved.". The
-// first check then ends in one of three ways:
-//
-// - It passes.
-// - It fails, because fetch cannot reach the endpoint.
-// - It gets an answer that holds an error.
-//
-// None of the three changes the stored URL or the flash message
-// (https://git.eeqj.de/sneak/AutistMask/issues/698).
-test.each([
-    {
-        button: "btn-save-rpc",
-        input: "settings-rpc",
-        field: "rpcUrl",
-        first: "passes",
-    },
-    {
-        button: "btn-save-rpc",
-        input: "settings-rpc",
-        field: "rpcUrl",
-        first: "fails",
-    },
-    {
-        button: "btn-save-rpc",
-        input: "settings-rpc",
-        field: "rpcUrl",
-        first: "answers with an error",
-    },
-    {
-        button: "btn-save-blockscout",
-        input: "settings-blockscout",
-        field: "blockscoutUrl",
-        first: "passes",
-    },
-    {
-        button: "btn-save-blockscout",
-        input: "settings-blockscout",
-        field: "blockscoutUrl",
-        first: "fails",
-    },
-    {
-        button: "btn-save-blockscout",
-        input: "settings-blockscout",
-        field: "blockscoutUrl",
-        first: "answers with an error",
-    },
-])(
-    "$button keeps the second tap's result when the first check $first last",
-    async ({ button, input, field, first }) => {
-        const page = await bootPopup(unversionedValidProfile());
-        await page.click("btn-settings");
-        const checks = [];
-        globalThis.fetch.mockImplementation(
-            () =>
-                new Promise((resolve, reject) => {
-                    checks.push({ resolve, reject });
-                }),
-        );
-        const secondUrl = "https://second.example.invalid";
-
-        page.node(input).value = "https://first.example.invalid";
-        const firstTap = page.node(button).listeners.click.map((fn) => fn());
-        await page.settle();
-        page.node(input).value = secondUrl;
-        const secondTap = page.node(button).listeners.click.map((fn) => fn());
-        await page.settle();
-        checks[1].resolve(PASSING_ANSWER);
-        await Promise.all(secondTap);
-        await page.settle();
-        expect(page.text("flash-msg")).toBe("Saved.");
-        if (first === "passes") {
-            checks[0].resolve(PASSING_ANSWER);
-        } else if (first === "answers with an error") {
-            checks[0].resolve(ERROR_ANSWER);
-        } else {
-            // fetch rejects when it cannot reach the endpoint.
-            checks[0].reject(new TypeError("Failed to fetch"));
-        }
-        await Promise.all(firstTap);
-        await page.settle();
-
-        expect(checks).toHaveLength(2);
-        expect(page.storage.read("autistmask")[field]).toBe(secondUrl);
-        expect(page.text("flash-msg")).toBe("Saved.");
-    },
-);
-
-// The user types a URL in Settings and taps "Save". Another write holds the
-// lock. So the save waits for the lock once the check passes. The user then
-// taps "Save" again on the same URL. When the lock is free, the first save
-// stores nothing and shows no flash message. The second check then passes, and
-// the second save stores the URL.
-test.each([
-    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
-    {
-        button: "btn-save-blockscout",
-        input: "settings-blockscout",
-        field: "blockscoutUrl",
-    },
-])(
-    "$button stores nothing for an earlier tap still waiting for the lock",
-    async ({ button, input, field }) => {
-        const page = await bootPopup(unversionedValidProfile());
-        await page.click("btn-settings");
-        const storedUrl = page.value(input);
-        const checks = [];
-        globalThis.fetch.mockImplementation(
-            () =>
-                new Promise((resolve) => {
-                    checks.push(resolve);
-                }),
-        );
-        const typedUrl = "https://typed.example.invalid";
-
-        page.node(input).value = typedUrl;
-        const firstTap = page.node(button).listeners.click.map((fn) => fn());
-        await page.settle();
-        let releaseLock;
-        const lockHeld = navigator.locks.request(
-            "autistmask",
-            () =>
-                new Promise((resolve) => {
-                    releaseLock = resolve;
-                }),
-        );
-        checks[0](PASSING_ANSWER);
-        await page.settle();
-        const secondTap = page.node(button).listeners.click.map((fn) => fn());
-        await page.settle();
-        releaseLock();
-        await lockHeld;
-        await Promise.all(firstTap);
-        await page.settle();
-
-        expect(page.storage.read("autistmask")[field]).toBe(storedUrl);
-        expect(page.text("flash-msg")).toBe("Testing endpoint...");
-
-        checks[1](PASSING_ANSWER);
-        await Promise.all(secondTap);
-        await page.settle();
-
-        expect(checks).toHaveLength(2);
-        expect(page.storage.read("autistmask")[field]).toBe(typedUrl);
-        expect(page.text("flash-msg")).toBe("Saved.");
-    },
-);
-
-// The user taps "Save", and the check passes. The save then begins its storage
-// write, and this test keeps the write waiting. The user taps "Save" again, and
-// the second check cannot reach the endpoint. When the write ends, the flash
-// message still reads "Could not reach endpoint.". The write stores the URL
-// anyway, because the write began before the second tap.
-test.each([
-    { button: "btn-save-rpc", input: "settings-rpc", field: "rpcUrl" },
-    {
-        button: "btn-save-blockscout",
-        input: "settings-blockscout",
-        field: "blockscoutUrl",
-    },
-])(
-    "$button keeps the second tap's message when tapped again during the write",
-    async ({ button, input, field }) => {
-        const page = await bootPopup(unversionedValidProfile());
-        await page.click("btn-settings");
-        const checks = [];
-        globalThis.fetch.mockImplementation(
-            () =>
-                new Promise((resolve, reject) => {
-                    checks.push({ resolve, reject });
-                }),
-        );
-        const typedUrl = "https://typed.example.invalid";
-
-        page.node(input).value = typedUrl;
-        const firstTap = page.node(button).listeners.click.map((fn) => fn());
-        await page.settle();
-        const { set } = page.storage.local;
-        const write = set.getMockImplementation();
-        let writeBegan = false;
-        let releaseWrite;
-        const writeHeld = new Promise((resolve) => {
-            releaseWrite = resolve;
-        });
-        set.mockImplementationOnce(async (items) => {
-            writeBegan = true;
-            await writeHeld;
-            await write(items);
-        });
-        checks[0].resolve(PASSING_ANSWER);
-        await page.settle();
-        expect(writeBegan).toBe(true);
-        const secondTap = page.node(button).listeners.click.map((fn) => fn());
-        await page.settle();
-        // fetch rejects when it cannot reach the endpoint.
-        checks[1].reject(new TypeError("Failed to fetch"));
-        await Promise.all(secondTap);
-        await page.settle();
-        expect(page.text("flash-msg")).toBe("Could not reach endpoint.");
-        releaseWrite();
-        await Promise.all(firstTap);
-        await page.settle();
-
-        expect(checks).toHaveLength(2);
-        expect(page.storage.read("autistmask")[field]).toBe(typedUrl);
-        expect(page.text("flash-msg")).toBe("Could not reach endpoint.");
-    },
-);

tests/transactionDetailLateAnswer.test.js

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

tests/uniswap.test.js

@@ -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