docs: say what a closed window does to a tx or sign approval (closes #505)

The approval port's disconnect handler leaves a transaction or signing
approval pending, and its comments said that was so the user could reopen
the toolbar popup. Those approvals open in their own window. When that
window closes, the windows.onRemoved listener rejects the approval, unless
an approved attempt is still running, in which case that attempt answers
the page. Both comments now say so. No code changed.

Model: opus-5-5

README.md

@@ -239,8 +239,12 @@ provide:
   `make check` stays non-mutating. Linting runs only in the container, because
   an ESLint result that depends on whichever ESLint the host happens to have is
   not a result, so docker is required to lint.
-- `script/fmt` — format all files (writes), on the host
+- `script/fmt` — format all files (writes), on the host, with the `prettier`
-- `script/fmt-check` — check formatting (read-only), on the host
+  that `script/bootstrap` installs in `node_modules/`; when that one is missing
+  it fails and says to run `script/bootstrap`, instead of using a `prettier`
+  from the `PATH`
+- `script/fmt-check` — check formatting (read-only), on the host, with the same
+  `prettier` and the same refusal
 - `script/check` — run `script/test`, `script/lint` and `script/fmt-check`
 - `script/check-censored` — assert the competitor name RULES.md bars appears
   nowhere in the working tree or under `dist/` outside its documented
@@ -2160,6 +2164,13 @@ view would leave a wallet one click from deletion.
     - Typed data that states no primary type, or one other than the type it
       would be signed as, or that cannot be read → shown with the error line
       saying so and "Sign" disabled; only "Reject" remains
+    - Typed data whose domain `chainId` names a chain other than the active
+      network's → shown with the error line naming both chain ids and "Sign"
+      disabled; only "Reject" remains. EIP-712 asks for this, because the
+      signature is valid on the chain the domain names. Typed data with no
+      `chainId` is not refused. The background refuses such a signature too,
+      against the network active when the signature reaches it, and answers the
+      site with the same sentence
     - A `personal_sign` or `eth_sign` message that is not hex (`0x` or `0X` and
       an even number of hex digits, the form ethers' `getBytes` reads when
       signing) → shown as plain text, with the error line "This message is plain
@@ -2678,11 +2689,7 @@ Currently supported:
   or recipient, and amount.
 - **Uniswap Universal Router**: `execute()` calls — shows swap direction (e.g.
   "Swap USDT → ETH"), token addresses, amounts, execution steps, and deadline.
-  Decodes Permit2, V2/V3/V4 swaps, wrap/unwrap, and balance checks. A V4 swap
+  Decodes Permit2, V2/V3/V4 swaps, wrap/unwrap, and balance checks.
-  action is read only in the parameter shape deployed on mainnet and Sepolia,
-  not in the newer one on `v4-periphery` `main`, which adds a `minHopPriceX36`
-  field. An action in any other shape is not read, and its step is listed as
-  `V4 Swap (could not be decoded)`.
 
 ### Non-Goals Forever
 

script/fmt

@@ -25,6 +25,13 @@ run_yarn() {
 
 main() {
     cd "$ROOT"
+    # Without the repo's own prettier, yarn runs whatever prettier is on
+    # the PATH, which may be a version that formats files differently.
+    if [ ! -x node_modules/.bin/prettier ]; then
+        echo "fmt: this repo's prettier is not installed in node_modules/," \
+            "so run script/bootstrap first." >&2
+        exit 1
+    fi
     echo "Formatting..."
     run_yarn run fmt
 }

script/fmt-check

@@ -26,6 +26,13 @@ run_yarn() {
 
 main() {
     cd "$ROOT"
+    # Without the repo's own prettier, yarn runs whatever prettier is on
+    # the PATH, which may be a version that formats files differently.
+    if [ ! -x node_modules/.bin/prettier ]; then
+        echo "fmt-check: this repo's prettier is not installed in" \
+            "node_modules/, so run script/bootstrap first." >&2
+        exit 1
+    fi
     echo "Checking formatting..."
     run_yarn run fmt-check
 }

src/background/index.js

@@ -22,6 +22,7 @@ const { debugFetch, log } = require("../shared/log");
 const {
     verifySignedTx,
     verifySignature,
+    typedDataChainRefusal,
     failureIsRetryable,
     describeTxFailure,
     sameAddress,
@@ -632,8 +633,9 @@ function isExtensionSender(sender) {
 // had refused.
 //
 // TX and sign approvals do not decide here. They stay pending across a
-// disconnect — the user can reopen the toolbar popup — and are rejected by the
+// disconnect. When their window closes, the windows.onRemoved listener below
-// windows.onRemoved listener below.
+// rejects them, unless an approved attempt is still running, in which case
+// that attempt answers the page.
 runtime.onConnect.addListener((port) => {
     if (port.name.startsWith("approval:")) {
         const id = port.name.split(":")[1];
@@ -661,7 +663,9 @@ runtime.onConnect.addListener((port) => {
             const approval = pendingApprovals[id];
             if (approval) {
                 if (approval.type === "tx" || approval.type === "sign") {
-                    // Keep pending — user can reopen the toolbar popup
+                    // When its window closes, windows.onRemoved rejects it,
+                    // unless an approved attempt is still running, in which
+                    // case that attempt answers the page.
                     return;
                 }
                 settleApproval(id, { approved: false, remember: false });
@@ -1764,7 +1768,8 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
 
         (async () => {
             try {
-                const activeAddress = await getActiveAddress();
+                const s = await getState();
+                const activeAddress = activeAddressOf(s);
                 // Same as the transaction path: the address the approval named
                 // is the one that must have signed, and a switch since then is
                 // a refusal rather than a signature from another account.
@@ -1783,6 +1788,20 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
                     signature,
                     approval.approvedFrom,
                 );
+                // The sign screen refuses typed data whose domain names
+                // another chain. A signature for it that arrives anyway is
+                // refused here, against the network active now.
+                const sp = approval.signParams;
+                if (
+                    sp.method === "eth_signTypedData_v4" ||
+                    sp.method === "eth_signTypedData"
+                ) {
+                    const refusal = typedDataChainRefusal(
+                        JSON.parse(sp.typedData).domain,
+                        networkById(s.networkId),
+                    );
+                    if (refusal) throw new ApprovalMismatchError(refusal);
+                }
                 settleApproval(msg.id, { signature }, { holdsClaim: true });
                 sendResponse({ signature });
             } catch (e) {

src/popup/index.html

@@ -7,9 +7,10 @@
         <link rel="stylesheet" href="styles.css" />
     </head>
     <!-- Chrome gives extension pages a stylesheet of its own that sets the
-         font on body, and a Tailwind class beats it only when marked
+         font and its size on body, and a Tailwind class beats it only when
-         important: hence font-mono! rather than font-mono. -->
+         marked important: hence font-mono! and text-sm! rather than
-    <body class="bg-bg text-fg font-mono! text-sm">
+         font-mono and text-sm. -->
+    <body class="bg-bg text-fg font-mono! text-sm!">
         <div id="app" class="p-2 pr-5 overflow-x-hidden">
             <!-- ============ GLOBAL TITLE BAR ============ -->
             <div
@@ -87,11 +88,14 @@
 
                 <!-- Mnemonic form section -->
                 <div id="add-wallet-section-mnemonic">
-                    <p class="mb-2">
+                    <!-- The die button shares the instruction's row: on a row
-                        Enter your 12 or 24 word recovery phrase below, or click
+                         of its own it pushes Import below the fold at
-                        the button to roll the die for a new one.
+                         360x600. -->
-                    </p>
+                    <div class="mb-2 flex justify-between items-start gap-2">
-                    <div class="mb-1 flex justify-end">
+                        <p>
+                            Enter your 12 or 24 word recovery phrase below, or
+                            click the button to roll the die for a new one.
+                        </p>
                         <button
                             id="btn-generate-phrase"
                             class="border border-border px-2 py-1 hover:bg-fg hover:text-bg cursor-pointer text-xs"

src/popup/views/approval.js

@@ -12,7 +12,7 @@ const {
     formatFee,
     tokenLabel,
 } = require("./helpers");
-const { state, saveState } = require("../../shared/state");
+const { state, saveState, currentNetwork } = require("../../shared/state");
 const {
     networkById,
     networkByChainId,
@@ -46,7 +46,10 @@ const {
 const { decryptWithPassword } = require("../../shared/vault");
 const { getSignerForAddress } = require("../../shared/wallet");
 const { walletDefect } = require("../../shared/walletDefects");
-const { describeSigningFailure } = require("../../shared/approvalVerify");
+const {
+    describeSigningFailure,
+    typedDataChainRefusal,
+} = require("../../shared/approvalVerify");
 const txStatus = require("./txStatus");
 const uniswap = require("../../shared/uniswap");
 const { notify, runtimeApi, sendMessage } = require("../../shared/browserApi");
@@ -443,7 +446,8 @@ function signedPrimaryType(types) {
 // Why a signature request cannot be signed, as a sentence for the error line,
 // or null when it can. Only typed data is refused: the `primaryType` the page
 // states has to be the type ethers will sign, or this screen would name one
-// message while another is signed.
+// message while another is signed. Its domain may name no chain but the active
+// network's.
 function typedDataRefusal(sp) {
     if (sp.method === "personal_sign" || sp.method === "eth_sign") return null;
     let data;
@@ -466,7 +470,7 @@ function typedDataRefusal(sp) {
             ", so it cannot be signed."
         );
     }
-    return null;
+    return typedDataChainRefusal(data.domain, currentNetwork());
 }
 
 // The largest amount a Permit2 allowance can hold, a uint160. Permit2 treats

src/shared/approvalVerify.js

@@ -53,6 +53,7 @@ const {
     accessListify,
     formatEther,
     getAddress,
+    getBigInt,
     getBytes,
     toQuantity,
     verifyMessage,
@@ -635,6 +636,33 @@ function verifySignature(signParams, signature, expectedFrom) {
     return recovered;
 }
 
+// Why typed data cannot be signed while `network` is the active network, as a
+// sentence, or null when it can. EIP-712 has a wallet refuse typed data whose
+// domain names another chain, because the signature is valid on that chain.
+// ethers signs no chain id when the domain's is null or absent, and reads any
+// other with getBigInt(), so 1, "1" and "0x1" are the same chain here too.
+function typedDataChainRefusal(domain, network) {
+    const chainId = domain?.chainId;
+    if (chainId === undefined || chainId === null) return null;
+    let named;
+    try {
+        named = getBigInt(chainId);
+    } catch {
+        return "This typed data cannot be read, so it cannot be signed.";
+    }
+    const active = getBigInt(network.chainId);
+    if (named === active) return null;
+    return (
+        "This typed data is for chain id " +
+        named +
+        ", but the active network is " +
+        network.name +
+        " (chain id " +
+        active +
+        "), so it cannot be signed."
+    );
+}
+
 // The stage a transaction approval failed at. Which stage it is decides
 // whether the approval survives the failure.
 const TX_STAGE_SIGN = "sign";
@@ -796,6 +824,7 @@ function describeSigningFailure(response, fallbackMessage) {
 module.exports = {
     verifySignedTx,
     verifySignature,
+    typedDataChainRefusal,
     assertNoForbiddenFields,
     assertNothingUnchecked,
     assertCanonicalBytes,

src/shared/uniswap.js

@@ -295,24 +295,6 @@ function v4ExactInAmount(raw) {
     return raw === 0n ? OPEN_DELTA : raw;
 }
 
-// The V4 swap actions are read only in the parameter structs V4Router has
-// deployed on mainnet and Sepolia. v4-periphery `main` has since added a
-// `minHopPriceX36` field to all four (`src/interfaces/IV4Router.sol`), and
-// reading a shape nobody has deployed would be guessing. ethers alone would
-// read the newer structs anyway: it takes whatever word sits where a
-// deployed field would be, ignores bytes left over, and holds back an error
-// in a field until that field is used. The newer multi-hop exact-in struct
-// then yields the offset of its hop-price array as `amountIn`. So a decode
-// counts only when encoding the result again gives back the same bytes;
-// otherwise this throws, and decodeV4Swap() marks the step as not decoded.
-function decodeExactly(types, data) {
-    const decoded = coder.decode(types, data);
-    if (coder.encode(types, decoded) !== data) {
-        throw new Error("Not in the deployed V4 parameter shape.");
-    }
-    return decoded;
-}
-
 // Decode V4_SWAP (command 0x10) input bytes.
 // The input is ABI-encoded as (bytes actions, bytes[] params).
 // We extract token addresses from SETTLE (input) and TAKE (output) sub-actions,
@@ -327,10 +309,6 @@ function decodeV4Swap(input) {
         let takeToken = null;
         let amountIn = null;
         let amountOutMin = null;
-        // Set when a swap action's parameters are not in the deployed shape
-        // (see decodeExactly()), so nothing was read from that action. SETTLE
-        // and TAKE may still name both currencies.
-        let swapUndecoded = false;
 
         for (let i = 0; i < actions.length; i++) {
             const actionId = actions[i];
@@ -359,7 +337,7 @@ function decodeV4Swap(input) {
                         //   tuple(address,uint24,int24,address,bytes)[] path,
                         //   uint128 amountIn, uint128 amountOutMin)
                         try {
-                            const s = decodeExactly(
+                            const s = coder.decode(
                                 [
                                     "tuple(address,tuple(address,uint24,int24,address,bytes)[],uint128,uint128)",
                                 ],
@@ -377,13 +355,13 @@ function decodeV4Swap(input) {
                                 amountOutMin = s[0][3];
                             }
                         } catch {
-                            swapUndecoded = true;
+                            // Fall through — SETTLE/TAKE will provide tokens
                         }
                     } else {
                         // ExactInputSingleParams: (tuple(address,address,uint24,int24,address) poolKey,
                         //   bool zeroForOne, uint128 amountIn, uint128 amountOutMin, bytes hookData)
                         try {
-                            const s = decodeExactly(
+                            const s = coder.decode(
                                 [
                                     "tuple(tuple(address,address,uint24,int24,address),bool,uint128,uint128,bytes)",
                                 ],
@@ -406,7 +384,7 @@ function decodeV4Swap(input) {
                                 amountOutMin = s[0][3];
                             }
                         } catch {
-                            swapUndecoded = true;
+                            // Fall through
                         }
                     }
                 } else if (
@@ -415,7 +393,7 @@ function decodeV4Swap(input) {
                 ) {
                     if (actionId === V4_SWAP_EXACT_OUT) {
                         try {
-                            const s = decodeExactly(
+                            const s = coder.decode(
                                 [
                                     "tuple(address,tuple(address,uint24,int24,address,bytes)[],uint128,uint128)",
                                 ],
@@ -427,11 +405,11 @@ function decodeV4Swap(input) {
                                 settleToken = path[path.length - 1][0];
                             }
                         } catch {
-                            swapUndecoded = true;
+                            // Fall through
                         }
                     } else {
                         try {
-                            const s = decodeExactly(
+                            const s = coder.decode(
                                 [
                                     "tuple(tuple(address,address,uint24,int24,address),bool,uint128,uint128,bytes)",
                                 ],
@@ -448,7 +426,7 @@ function decodeV4Swap(input) {
                                     ? poolKey[1]
                                     : poolKey[0];
                         } catch {
-                            swapUndecoded = true;
+                            // Fall through
                         }
                     }
                 }
@@ -462,7 +440,6 @@ function decodeV4Swap(input) {
             tokenOut: takeToken,
             amountIn,
             amountOutMin,
-            swapUndecoded,
         };
     } catch {
         return null;
@@ -591,11 +568,6 @@ function decode(data, toAddress, sources) {
                 if (cmdId === 0x10) {
                     const v4 = decodeV4Swap(inputs[i]);
                     if (v4) {
-                        // Without this, a swap action that went unread would
-                        // look like one that had nothing to show.
-                        if (v4.swapUndecoded) {
-                            commandNames[i] += " (could not be decoded)";
-                        }
                         setInputOnce(v4.tokenIn, v4.amountIn);
                         // Always update output: last swap step wins. A step
                         // that carries the Min. received figure but decoded no

tests/backgroundApproval.test.js

@@ -397,7 +397,13 @@ function loadBackground(options) {
                 rpcResult = r;
             },
         );
-        return { result: () => rpcResult };
+        return {
+            id: () =>
+                new URL(created[created.length - 1].url).searchParams.get(
+                    "approval",
+                ),
+            result: () => rpcResult,
+        };
     }
 
     // A dApp asking to connect. The origin defaults to one the persisted
@@ -1484,6 +1490,55 @@ describe("what the approval is verified against", () => {
         });
     });
 
+    // Typed data whose domain names another chain is refused on the sign
+    // screen; a signature for it that reaches the background anyway is not
+    // handed to the page (https://git.eeqj.de/sneak/AutistMask/issues/519).
+    // TYPED_DATA names mainnet.
+    async function answerTypedData(bg, pending) {
+        const { domain, types, message } = JSON.parse(TYPED_DATA);
+        delete types.EIP712Domain;
+        const signature = await signer.signTypedData(domain, types, message);
+        const answer = bg.send(
+            {
+                type: "AUTISTMASK_SIGN_RESPONSE",
+                id: pending.id(),
+                approved: true,
+                signature,
+            },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+        return { answer, signature };
+    }
+
+    test("typed data for the active chain is handed back signed", async () => {
+        const bg = loadBackground();
+        const pending = bg.requestTypedData();
+        await settle();
+
+        const { answer, signature } = await answerTypedData(bg, pending);
+
+        expect(answer.sendResponse).toHaveBeenCalledWith({ signature });
+        expect(pending.result()).toEqual({ result: signature });
+    });
+
+    test("typed data for another chain is refused, not handed back", async () => {
+        const bg = loadBackground();
+        bg.setNetwork(SEPOLIA);
+        const pending = bg.requestTypedData();
+        await settle();
+
+        const { answer } = await answerTypedData(bg, pending);
+
+        const refusal =
+            "This typed data is for chain id 1, but the active network is Sepolia Testnet (chain id 11155111), so it cannot be signed.";
+        expect(answer.sendResponse).toHaveBeenCalledWith({
+            error: refusal,
+            retryable: false,
+        });
+        expect(pending.result()).toEqual({ error: { message: refusal } });
+    });
+
     test("a sign request from another address raises no approval at all", async () => {
         const bg = loadBackground();
         const pending = bg.requestSign(other.address);

tests/e2e/firefox/run.js

@@ -128,6 +128,18 @@ step("the popup is drawn in the monospace font it declares", async (env) => {
     );
 });
 
+// The same check as the Chrome suite's (#456), so both browsers are held to
+// the same size.
+step("the popup's text is drawn at the 14px text-sm declares", async (env) => {
+    const size = await env.driver.execute(
+        "return getComputedStyle(document.body).fontSize;",
+    );
+    assert(
+        size === "14px",
+        "the popup's text is drawn at " + size + ", not at the 14px of text-sm",
+    );
+});
+
 // The recovery screen (#361): the Chrome suite's four cases, run before any
 // wallet exists for the same reason. With no wallet nothing saves on a timer,
 // so no save can write a good record over the unreadable one. The last of them

tests/e2e/run.js

@@ -113,6 +113,18 @@ test("the popup is drawn in the monospace font it declares (#418)", async (env)
     );
 });
 
+// The same stylesheet sets the size on body to 75%, which would draw the
+// popup at 12px.
+test("the popup's text is drawn at the 14px text-sm declares (#456)", async (env) => {
+    const size = await env.page.evaluate(
+        () => getComputedStyle(document.body).fontSize,
+    );
+    assert(
+        size === "14px",
+        "the popup's text is drawn at " + size + ", not at the 14px of text-sm",
+    );
+});
+
 // The empirical half of #182. The manifest change is only a claim about
 // what the CSP permits; this is the observation. Two things have to hold
 // together, and the run covers both: the popup realm compiles WASM (here),

tests/typedDataPermit.test.js

@@ -240,6 +240,7 @@ function request(data) {
 beforeEach(() => {
     state.trackedTokens = [];
     state.wallets = [];
+    state.networkId = "mainnet";
 });
 
 describe("a token permission is warned about, naming spender and amount", () => {
@@ -532,3 +533,66 @@ describe("the sign screen refuses a mismatched primary type", () => {
         expect(node("btn-approve-sign").disabled).toBe(true);
     });
 });
+
+// EIP-712: a wallet refuses typed data whose domain names a chain other than
+// the active one, because the signature is valid on the chain it names
+// (https://git.eeqj.de/sneak/AutistMask/issues/519). The wallet is on Sepolia
+// and the site asks for a mainnet USDC Permit.
+describe("the sign screen refuses typed data for another chain", () => {
+    const REFUSAL =
+        "This typed data is for chain id 1, but the active network is Sepolia Testnet (chain id 11155111), so it cannot be signed.";
+
+    function withChainId(chainId) {
+        return { ...PERMIT, domain: { ...PERMIT.domain, chainId } };
+    }
+
+    beforeEach(() => {
+        decryptWithPassword.mockClear();
+        state.networkId = "sepolia";
+    });
+
+    test("another chain shows the error, with Sign disabled", async () => {
+        await openSignScreen(PERMIT);
+        expect(node("approve-sign-error").textContent).toBe(REFUSAL);
+        expect(node("btn-approve-sign").disabled).toBe(true);
+    });
+
+    test("Sign clicked anyway decrypts and signs nothing", async () => {
+        const sent = await openSignScreen(PERMIT);
+        node("approve-sign-password").value = "any password";
+        await click("btn-approve-sign");
+
+        expect(decryptWithPassword).not.toHaveBeenCalled();
+        expect(sent.map((msg) => msg.type)).not.toContain(
+            "AUTISTMASK_SIGN_RESPONSE",
+        );
+        expect(node("approve-sign-error").textContent).toBe(REFUSAL);
+    });
+
+    // ethers signs 1, "1" and "0x1" as the same chain id.
+    test("the chain id is refused in each form ethers signs", () => {
+        for (const chainId of [1, "1", "0x1"]) {
+            expect(typedDataRefusal(request(withChainId(chainId)))).toBe(
+                REFUSAL,
+            );
+        }
+    });
+
+    test("a chain id that is not a number is refused", () => {
+        expect(typedDataRefusal(request(withChainId("mainnet")))).toBe(
+            "This typed data cannot be read, so it cannot be signed.",
+        );
+    });
+
+    test("the active chain leaves Sign enabled", async () => {
+        await openSignScreen(withChainId("0xaa36a7"));
+        expect(node("approve-sign-error").textContent).toBe("");
+        expect(node("btn-approve-sign").disabled).toBe(false);
+    });
+
+    test("no chain id leaves Sign enabled", async () => {
+        await openSignScreen(withChainId(undefined));
+        expect(node("approve-sign-error").textContent).toBe("");
+        expect(node("btn-approve-sign").disabled).toBe(false);
+    });
+});

tests/uniswap.test.js

@@ -163,110 +163,6 @@ function encodeV4ExactInSingle(currency0, currency1, amountIn, amountOutMin) {
     );
 }
 
-// Each V4 swap action's parameters in two shapes: the struct V4Router has
-// deployed on mainnet and Sepolia, and the one v4-periphery `main` has since
-// moved to, which adds a `minHopPriceX36` field. Each swaps WETH for USDC.
-const POOL_KEY = "tuple(address,address,uint24,int24,address)";
-const PATH_KEY = "tuple(address,uint24,int24,address,bytes)";
-const WETH_USDC_POOL = [WETH_ADDR, USDC_ADDR, 100, 1, ZERO_ADDR];
-const ONE_WETH = 1000000000000000000n;
-const V4_SWAP_ACTION_SHAPES = [
-    {
-        action: "SWAP_EXACT_IN_SINGLE",
-        id: 0x06,
-        deployed: coder.encode(
-            [`tuple(${POOL_KEY},bool,uint128,uint128,bytes)`],
-            [[WETH_USDC_POOL, true, ONE_WETH, 990000n, "0x"]],
-        ),
-        newer: coder.encode(
-            [`tuple(${POOL_KEY},bool,uint128,uint128,uint256,bytes)`],
-            [[WETH_USDC_POOL, true, ONE_WETH, 990000n, 0n, "0x"]],
-        ),
-    },
-    {
-        action: "SWAP_EXACT_IN",
-        id: 0x07,
-        deployed: coder.encode(
-            [`tuple(address,${PATH_KEY}[],uint128,uint128)`],
-            [
-                [
-                    WETH_ADDR,
-                    [[USDC_ADDR, 100, 1, ZERO_ADDR, "0x"]],
-                    ONE_WETH,
-                    990000n,
-                ],
-            ],
-        ),
-        newer: coder.encode(
-            [`tuple(address,${PATH_KEY}[],uint256[],uint128,uint128)`],
-            [
-                [
-                    WETH_ADDR,
-                    [[USDC_ADDR, 100, 1, ZERO_ADDR, "0x"]],
-                    [],
-                    ONE_WETH,
-                    990000n,
-                ],
-            ],
-        ),
-    },
-    {
-        action: "SWAP_EXACT_OUT_SINGLE",
-        id: 0x08,
-        deployed: coder.encode(
-            [`tuple(${POOL_KEY},bool,uint128,uint128,bytes)`],
-            [[WETH_USDC_POOL, true, 990000n, ONE_WETH, "0x"]],
-        ),
-        newer: coder.encode(
-            [`tuple(${POOL_KEY},bool,uint128,uint128,uint256,bytes)`],
-            [[WETH_USDC_POOL, true, 990000n, ONE_WETH, 0n, "0x"]],
-        ),
-    },
-    {
-        action: "SWAP_EXACT_OUT",
-        id: 0x09,
-        deployed: coder.encode(
-            [`tuple(address,${PATH_KEY}[],uint128,uint128)`],
-            [
-                [
-                    USDC_ADDR,
-                    [[WETH_ADDR, 100, 1, ZERO_ADDR, "0x"]],
-                    990000n,
-                    ONE_WETH,
-                ],
-            ],
-        ),
-        newer: coder.encode(
-            [`tuple(address,${PATH_KEY}[],uint256[],uint128,uint128)`],
-            [
-                [
-                    USDC_ADDR,
-                    [[WETH_ADDR, 100, 1, ZERO_ADDR, "0x"]],
-                    [],
-                    990000n,
-                    ONE_WETH,
-                ],
-            ],
-        ),
-    },
-];
-
-// Helper: execute() with one V4_SWAP step holding the swap action, then
-// SETTLE of WETH and TAKE of USDC.
-function v4SwapCalldata(actionId, swapParams) {
-    return buildExecute(
-        "0x10",
-        [
-            encodeV4Swap(new Uint8Array([actionId, V4_SETTLE_ID, V4_TAKE_ID]), [
-                swapParams,
-                encodeV4Settle(WETH_ADDR),
-                encodeV4Take(USDC_ADDR),
-            ]),
-        ],
-        9999999999n,
-    );
-}
-
 function detail(result, label) {
     return result.details.find((d) => d.label === label);
 }
@@ -307,45 +203,11 @@ describe("uniswap decoder", () => {
             result.details.find((d) => d.label === "Min. received").value,
         ).toBe("0.0002 ETH");
 
-        // Real mainnet calldata is in the deployed shape, so its V4 step is
-        // not said to be undecoded.
         const steps = result.details.find((d) => d.label === "Steps");
-        expect(steps.value).toBe("Permit2 Permit → V4 Swap");
+        expect(steps.value).toContain("Permit2 Permit");
+        expect(steps.value).toContain("V4 Swap");
     });
 
-    test.each(V4_SWAP_ACTION_SHAPES)(
-        "a V4 $action in the deployed shape is read",
-        ({ id, deployed }) => {
-            const result = uniswap.decode(
-                v4SwapCalldata(id, deployed),
-                ROUTER_ADDR,
-            );
-            expect(detail(result, "Steps").value).toBe("V4 Swap");
-        },
-    );
-
-    // https://git.eeqj.de/sneak/AutistMask/issues/358 — before it, all four
-    // newer structs decoded as the deployed ones without an error, and the
-    // newer SWAP_EXACT_IN showed the offset of its hop-price array as Amount
-    // ("0.0000000000000004 WETH") and its amountIn as Min. received.
-    test.each(V4_SWAP_ACTION_SHAPES)(
-        "a V4 $action in the newer periphery shape is shown as not decoded",
-        ({ id, newer }) => {
-            const result = uniswap.decode(
-                v4SwapCalldata(id, newer),
-                ROUTER_ADDR,
-            );
-            expect(detail(result, "Amount")).toBeUndefined();
-            expect(detail(result, "Min. received")).toBeUndefined();
-            expect(detail(result, "Steps").value).toBe(
-                "V4 Swap (could not be decoded)",
-            );
-            // SETTLE and TAKE keep their own shape and still name both sides.
-            expect(detail(result, "Token In").address).toBe(WETH_ADDR);
-            expect(detail(result, "Token Out").address).toBe(USDC_ADDR);
-        },
-    );
-
     test("decodes V2_SWAP_EXACT_IN with known tokens", () => {
         const data = buildExecute(
             "0x08", // V2_SWAP_EXACT_IN
@@ -686,11 +548,9 @@ describe("uniswap decoder", () => {
         const result = uniswap.decode(data, ROUTER_ADDR);
         expect(result).not.toBeNull();
 
-        // The V4 swap action's parameters are empty, so that step is said to
-        // be undecoded.
         const steps = result.details.find((d) => d.label === "Steps");
         expect(steps.value).toBe(
-            "Permit2 Permit \u2192 V4 Swap (could not be decoded) \u2192 Unwrap WETH",
+            "Permit2 Permit \u2192 V4 Swap \u2192 Unwrap WETH",
         );
     });