fix: a swap split across steps the user pays for shows every amount it spends (closes #625)

The swap's Amount line took only the first swap step's amount. It now
gives the total the steps take of Token In: the amount of the step that
sets the input side plus what each later step the user pays takes of it.
A take of another token, one after an amount that is not a quantity, or
one the decoder cannot tell, gets lines of its own; an unread take, a
V3_SWAP_EXACT_OUT's included, leaves no figure. A V4 step counts every
SETTLE paid by the user and every SETTLE_ALL. A PERMIT2_PERMIT names
Token In, and its amount stands only in the plain shape of Uniswap's own
routes, with every later step read.

Model: opus-5-5

README.md

@@ -3153,36 +3153,40 @@ Currently supported:
   included, stands as the `Amount` figure in place of the total only in the
   plain shape of Uniswap's own routes: it is the only `PERMIT2_PERMIT`, its
   spender is the router, the router may not let it fail, no step before it takes
-  its token or a token the decoder does not know, and no `PERMIT2_PERMIT_BATCH`
-  comes after it. Permit2 then lets the router take no more of the token than
-  that amount, so the permit covers every take of it. In any other case the line
-  gives the total, as with no permit. When the step that sets the input side
-  spends a token other than the permit's, or one the decoder does not know, its
-  amount gets lines of its own and the total has no figure to start from: unless
-  the permit's amount stands there is no `Amount` line, and each take of the
-  permit's token gets lines of its own. Each take the total does not count gives
-  three lines after the `Amount` line (after `Token In` when there is none): one
-  of a token other than `Token In`; one of `Token In` after an amount that is
-  not a quantity (a V4 open delta, `ALREADY_PAID`, which keep their wording on
-  the `Amount` line, or no stated amount, as of a V4 exact-out step); and one
-  whose amount the decoder does not know. They come in step order, the step that
-  sets the input side first when it has them: `Moved from the sender`, its
-  amount, worded as the `Amount` line words one, or
-  `Unknown (could not be decoded)` when the decoder does not know it;
-  `Token moved`, giving the token's address as the `Token In` line does; and
-  `Moved to`, which reads `The swap step that spends it`. A token the decoder
-  does not know gives the `Moved from the sender` line alone. A step may also
-  take from the user's wallet what the decoder did not read: a V4 step, other
-  than the one that sets the input side, whose input or one of whose `SETTLE`s
-  or `SETTLE_ALL`s it cannot read, which the router still runs; a V2 or V3
-  exact-in or V2 exact-out step or a `PERMIT2_TRANSFER_FROM` whose input it
-  cannot read; and every `PERMIT2_TRANSFER_FROM_BATCH`. Each such step gives one
-  `Moved from the sender` line among those, reading
-  `Unknown (could not be decoded)`. That line, or any line for a token the
-  decoder does not know, leaves no `Amount` line, whose figure might be too low.
-  Then each `PERMIT2_TRANSFER_FROM` but one into the router, in step order,
-  gives three lines: `Moved from the sender`, the amount it moves, for example
-  `1000000.0000 USDT`; `Token moved`, giving the token's address as the
+  its token or a token the decoder does not know, and the decoder reads every
+  step after it in full. Permit2 then lets the router take no more of the token
+  than that amount, so the permit covers every take of it. A step the decoder
+  does not read in full may raise what Permit2 lets the router take, as a
+  `PERMIT2_PERMIT_BATCH` can: a command the decoder does not read (listed at the
+  end of this section), a step whose input it cannot read, in whole or in part,
+  and a step it fails on. In any other case the line gives the total, as with no
+  permit. When the step that sets the input side spends a token other than the
+  permit's, or one the decoder does not know, its amount gets lines of its own
+  and the total has no figure to start from: unless the permit's amount stands
+  there is no `Amount` line, and each take of the permit's token gets lines of
+  its own. Each take the total does not count gives three lines after the
+  `Amount` line (after `Token In` when there is none): one of a token other than
+  `Token In`; one of `Token In` after an amount that is not a quantity (a V4
+  open delta, `ALREADY_PAID`, which keep their wording on the `Amount` line, or
+  no stated amount, as of a V4 exact-out step); and one whose amount the decoder
+  does not know. They come in step order, the step that sets the input side
+  first when it has them: `Moved from the sender`, its amount, worded as the
+  `Amount` line words one, or `Unknown (could not be decoded)` when the decoder
+  does not know it; `Token moved`, giving the token's address as the `Token In`
+  line does; and `Moved to`, which reads `The swap step that spends it`. A token
+  the decoder does not know gives the `Moved from the sender` line alone. A step
+  may also take from the user's wallet what the decoder did not read: a V4 step,
+  other than the one that sets the input side, whose input or one of whose
+  `SETTLE`s or `SETTLE_ALL`s it cannot read, which the router still runs; a V2
+  or V3 exact-in or V2 exact-out step or a `PERMIT2_TRANSFER_FROM` whose input
+  it cannot read; every `PERMIT2_TRANSFER_FROM_BATCH`; and, once the input side
+  is set, every `V3_SWAP_EXACT_OUT`, which the decoder does not read, and every
+  step it fails on. Each such step gives one `Moved from the sender` line among
+  those, reading `Unknown (could not be decoded)`. That line, or any line for a
+  token the decoder does not know, leaves no `Amount` line, whose figure might
+  be too low. Then each `PERMIT2_TRANSFER_FROM` but one into the router, in step
+  order, gives three lines: `Moved from the sender`, the amount it moves, for
+  example `1000000.0000 USDT`; `Token moved`, giving the token's address as the
   `Token In` line does; and `Moved to`, which reads
   `The V2 pair the next swap spends` for a hop and `The sender` for `address(1)`
   on every router but `UniversalRouterV1`, and otherwise gives the address. A

src/shared/uniswap.js

@@ -1169,6 +1169,10 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // The last PERMIT2_PERMIT this decoder read, or null (see
         // permitStands after the loop).
         let permit = null;
+        // The index of each step this decoder did not read in full: a
+        // command it does not read, a step whose input it cannot read, in
+        // whole or in part, and one it fails on (see permitStands).
+        const stepsUnread = [];
         let outputToken = null;
         let minOutput = null;
         let outputEstablished = false;
@@ -1229,10 +1233,11 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // A step may take from the sender what this decoder did not read: a
         // V4 step, other than the one that sets the input side, whose input
         // or one of whose SETTLEs or SETTLE_ALLs it cannot read; a V2 or V3
-        // swap step or PERMIT2_TRANSFER_FROM whose input it cannot read; or a
-        // PERMIT2_TRANSFER_FROM_BATCH. It is recorded with a null token and
-        // amount: one line says so, and there is no Amount line, whose figure
-        // may then be too low.
+        // exact-in or V2 exact-out step or PERMIT2_TRANSFER_FROM whose input
+        // it cannot read; a PERMIT2_TRANSFER_FROM_BATCH; and, once the input
+        // side is set, a V3_SWAP_EXACT_OUT or a step it fails on. It is
+        // recorded with a null token and amount: one line says so, and there
+        // is no Amount line, whose figure may then be too low.
         const spentUnread = () => {
             userPaid.push({ token: null, amount: null });
         };
@@ -1371,6 +1376,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     hasSubPlan = true;
                     commandNames[i] += " (its steps are not shown)";
                     payeeUnread = true;
+                    stepsUnread.push(i);
                 } else if (command === "PERMIT2_PERMIT") {
                     const p = decodePermit2(inputs[i]);
                     if (p) {
@@ -1389,11 +1395,14 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                             allowedToFail,
                             beforeEveryTake: !tookBefore,
                         };
+                    } else {
+                        stepsUnread.push(i);
                     }
                 } else if (command === "PERMIT2_TRANSFER_FROM") {
                     const p = decodePermit2TransferFrom(inputs[i]);
                     if (!p) {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                         spentUnread();
                     } else if (
                         commandTypeMask === 0x1f &&
@@ -1432,6 +1441,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         // owner may be any address. It sets no side, and the
                         // step says so.
                         commandNames[i] += " (could not be decoded)";
+                        stepsUnread.push(i);
                     } else if (b.owner.toLowerCase() !== sender) {
                         // The router reads the owner as written (see
                         // decodeBalanceCheck()), so address(1) and address(2)
@@ -1473,8 +1483,17 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                         spentUnread();
                     }
+                } else if (command === "V3_SWAP_EXACT_OUT") {
+                    // This decoder does not read it
+                    // (https://git.eeqj.de/sneak/AutistMask/issues/601). It
+                    // may pay any address and take from the sender, so once
+                    // the input side is set it leaves no Amount figure.
+                    payeeUnread = true;
+                    stepsUnread.push(i);
+                    if (inputEstablished) spentUnread();
                 } else if (command === "V2_SWAP_EXACT_IN") {
                     const s = decodeV2SwapExactIn(inputs[i]);
                     if (s) {
@@ -1492,6 +1511,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                         spentUnread();
                     }
                 } else if (command === "V2_SWAP_EXACT_OUT") {
@@ -1510,12 +1530,14 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                         spentUnread();
                     }
                 } else if (command === "PERMIT2_TRANSFER_FROM_BATCH") {
                     // It moves the sender's tokens to any addresses, and this
                     // decoder does not read it.
                     payeeUnread = true;
+                    stepsUnread.push(i);
                     spentUnread();
                 } else if (command === "SWEEP") {
                     const s = decodeSweep(inputs[i]);
@@ -1526,6 +1548,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                     }
                 } else if (
                     command === "TRANSFER" ||
@@ -1562,6 +1585,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                     }
                 } else if (command === "ACROSS_V4_DEPOSIT_V3") {
                     const a = decodeAcrossV4DepositV3(inputs[i]);
@@ -1585,6 +1609,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                     }
                 } else if (command === "WRAP_ETH") {
                     const w = decodeWrapEth(inputs[i]);
@@ -1615,6 +1640,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                     }
                 } else if (command === "V4_SWAP") {
                     const v4 = decodeV4Swap(inputs[i]);
@@ -1634,6 +1660,14 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     if (!v4 || v4.recipientUnread) {
                         payeeUnread = true;
                     }
+                    if (
+                        !v4 ||
+                        v4.recipientUnread ||
+                        v4.settleUnread ||
+                        v4.swapUndecoded
+                    ) {
+                        stepsUnread.push(i);
+                    }
                     if (v4 && v4.swapUndecoded) {
                         // A swap action of this step went unread, so the step
                         // is marked.
@@ -1701,16 +1735,21 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         }
                     } else {
                         payeeUnread = true;
+                        stepsUnread.push(i);
                     }
                 } else {
                     // Any other step may pay an address this decoder does not
-                    // read: V3_SWAP_EXACT_OUT and the NFT commands among them,
-                    // and a type the release names no command for.
+                    // read: PERMIT2_PERMIT_BATCH and the NFT commands among
+                    // them, and a type the release names no command for.
                     payeeUnread = true;
+                    stepsUnread.push(i);
                 }
             } catch {
-                // Skip commands we can't decode. One may pay any address.
+                // Skip commands we can't decode. One may pay any address and
+                // take from the sender.
                 payeeUnread = true;
+                stepsUnread.push(i);
+                if (inputEstablished) spentUnread();
             }
             if (allowedToFail) {
                 commandNames[i] += " (allowed to fail)";
@@ -1731,12 +1770,15 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // the Amount figure in place of the total only in the plain shape of
         // Uniswap's own routes: it is the only PERMIT2_PERMIT, its spender is
         // the router, the router may not let it fail, no step before it took
-        // its token or one not known, and no PERMIT2_PERMIT_BATCH comes after
-        // it. Permit2 then
-        // lets the router take no more of the token than that amount, so the
-        // permit covers every take of it. A step this decoder does not read
-        // that may take from the sender leaves no figure in any case, and an
-        // EXECUTE_SUB_PLAN step leaves both sides unknown (below).
+        // its token or one not known, and this decoder read every step after
+        // it in full (see stepsUnread). Permit2 then lets the router take no
+        // more of the token than that amount, so the permit covers every take
+        // of it. A later step this decoder did not read may raise what Permit2
+        // lets the router take, as a PERMIT2_PERMIT_BATCH can. A step this
+        // decoder does not read that may take from the sender leaves no
+        // figure, permit or not, when it comes after the step that sets the
+        // input side (see spentUnread()), and an EXECUTE_SUB_PLAN step leaves
+        // both sides unknown (below).
         const stepCommands = Array.from(
             commandsBytes,
             (b) => commands[b & commandTypeMask],
@@ -1747,9 +1789,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             sameAddress(permit.spender, toAddress) &&
             !permit.allowedToFail &&
             permit.beforeEveryTake &&
-            !stepCommands
-                .slice(permit.step + 1)
-                .includes("PERMIT2_PERMIT_BATCH");
+            !stepsUnread.some((step) => step > permit.step);
         // What the steps take that the Amount line does not give, as
         // { token, amount }. A null token is a step this decoder did not read
         // (see spentUnread()), or a token it does not know.

tests/uniswap.test.js

@@ -1830,6 +1830,70 @@ describe("uniswap decoder", () => {
             ]);
         });
 
+        // Any other step this decoder does not read may do the same, for
+        // example through the hook of the pool a V4_INITIALIZE_POOL sets up.
+        test.each([
+            {
+                kind: "a V4_INITIALIZE_POOL",
+                command: 0x13,
+                input: coder.encode(
+                    [POOL_KEY, "uint160"],
+                    [
+                        [USDC_ADDR, USDT_ADDR, 3000, 60, OTHER_ADDR],
+                        79228162514264337593543950336n,
+                    ],
+                ),
+            },
+            {
+                kind: "a SWEEP whose input cannot be read",
+                command: 0x04,
+                input: dirtyWord(
+                    coder.encode(
+                        ["address", "address", "uint256"],
+                        [USDC_ADDR, USER_ADDR, 0n],
+                    ),
+                    1,
+                ),
+            },
+        ])(
+            "a split after a PERMIT2_PERMIT, with $kind between its steps, shows the total the steps take",
+            ({ command, input }) => {
+                const result = decodeSteps(
+                    [0x0a, 0x00, command, 0x08],
+                    [
+                        encodePermit2(USDT_ADDR, USDT_600, ROUTER_ADDR),
+                        V3_600,
+                        input,
+                        encodeV2SwapExactIn(USER_ADDR, 9400000000n, 1n, [
+                            USDT_ADDR,
+                            USDC_ADDR,
+                        ]),
+                    ],
+                );
+                expect(linesBetweenTokens(result)).toEqual([
+                    ["Amount", "10000.0000 USDT"],
+                ]);
+            },
+        );
+
+        // This decoder does not read a V3_SWAP_EXACT_OUT, so what one takes
+        // after the step that sets the input side leaves no Amount figure.
+        test("a V3 exact-in of 600 USDT, then a V3_SWAP_EXACT_OUT the user pays for, shows no Amount figure", () => {
+            // Its input is (recipient, amountOut, amountInMax, path,
+            // payerIsUser), laid out as encodeV3SwapExactIn() writes one; an
+            // exact-out path lists the token bought first.
+            const exactOut = encodeV3SwapExactIn(
+                USER_ADDR,
+                390000000n,
+                USDT_400,
+                [USDC_ADDR, USDT_ADDR],
+            );
+            const result = decodeSteps([0x00, 0x01], [V3_600, exactOut]);
+            expect(linesBetweenTokens(result)).toEqual([
+                ["Moved from the sender", UNDECODED],
+            ]);
+        });
+
         // A later step's amount that cannot be added to the Amount line,
         // because the amount of the step that set the input side is not a
         // quantity, gets lines of its own.