fix: a permit on the zero address never reads as ETH (closes #660)

Permit2 has no allowance of ETH, but the swap decoder read a permit's
zero-address token as ETH. Its Allowance token line read ETH. A permit of
1 wei of the zero address before a V4 step of 5 ETH stood as the Amount
figure, which then read 0.000000000000000001 ETH. With that permit to
another spender, there was no Amount line.

Such a permit now never stands as the Amount figure. To another spender,
it no longer removes the Amount line either. Its lines give the amount in
base units and name the zero address, as for a token nothing knows.

Model: opus-5-5

src/shared/uniswap.js

@@ -2032,12 +2032,14 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // it may take more. A later permit or batch, or a later step this
         // decoder did not read, may raise what Permit2 lets the router take.
         // Every other PERMIT2_PERMIT leaves Token In and the Amount line as
-        // they read with no permit, and gets lines of its own below. A step
-        // that may take from the sender what this decoder did not read leaves
-        // no figure, permit or not (see spentUnread()), and so do a permit
-        // or batch whose input it cannot read (see permitUnread()) and an
-        // allowance of Token In to another spender (see toAnotherSpender). An
-        // EXECUTE_SUB_PLAN step leaves both sides unknown (below).
+        // they read with no permit, and gets lines of its own below. A permit
+        // on the zero address never stands as the Amount figure, because
+        // Permit2 has no allowance of ETH. A step that may take from the
+        // sender what this decoder did not read leaves no figure, permit or
+        // not (see spentUnread()), and so do a permit or batch whose input it
+        // cannot read (see permitUnread()) and an allowance of Token In to
+        // another spender (see toAnotherSpender). An EXECUTE_SUB_PLAN step
+        // leaves both sides unknown (below).
         const stepCommands = Array.from(
             commandsBytes,
             (b) => commands[b & commandTypeMask],
@@ -2047,6 +2049,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             stepCommands.filter((c) => c === "PERMIT2_PERMIT").length === 1 &&
             !stepCommands.includes("PERMIT2_PERMIT_BATCH") &&
             sameAddress(permit.spender, toAddress) &&
+            permit.token !== "0x0000000000000000000000000000000000000000" &&
             !permit.allowedToFail &&
             permit.beforeEveryTake &&
             !stepsUnread.some((step) => step > permit.step);
@@ -2234,17 +2237,19 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // A null token in `spentFromSender`, a step this decoder did not read
         // or a token it does not know, and an allowance to another spender
         // that may be of Token In, leave no Amount figure, which may then be
-        // too low. With no Amount line, each take the total adds up gets
-        // lines of its own, first, so that every amount this decoder read is
-        // shown.
+        // too low. An allowance of the zero address is never one of Token In,
+        // because Permit2 has no allowance of ETH. With no Amount line, each
+        // take the total adds up gets lines of its own, first, so that every
+        // amount this decoder read is shown.
         if (
             present(inputAmount) &&
             spentFromSender.every((s) => present(s.token)) &&
             toAnotherSpender.every(
                 (p) =>
-                    present(p.token) &&
-                    present(inputToken) &&
-                    !sameAddress(p.token, inputToken),
+                    p.token === "0x0000000000000000000000000000000000000000" ||
+                    (present(p.token) &&
+                        present(inputToken) &&
+                        !sameAddress(p.token, inputToken)),
             )
         ) {
             const amount = spentText(inputAmount, inInfo);
@@ -2315,15 +2320,36 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                 });
                 continue;
             }
-            details.push({
-                label: "Permit2 allowance",
-                value:
-                    p.amount >= MAX_UINT160
-                        ? "Unlimited"
-                        : amountText(p.amount, tokenInfo(p.token, sources))
-                              .display,
-            });
-            details.push(tokenMovedLine("Allowance token", p.token, sources));
+            // Permit2 has no allowance of ETH. An allowance of the zero
+            // address reads as one of a token nothing knows: its amount in
+            // base units, and the zero address as its token.
+            if (p.token === "0x0000000000000000000000000000000000000000") {
+                details.push({
+                    label: "Permit2 allowance",
+                    value:
+                        p.amount >= MAX_UINT160
+                            ? "Unlimited"
+                            : unknownDecimalsAmount(p.amount),
+                });
+                details.push({
+                    label: "Allowance token",
+                    value: p.token,
+                    address: p.token,
+                    isToken: true,
+                });
+            } else {
+                details.push({
+                    label: "Permit2 allowance",
+                    value:
+                        p.amount >= MAX_UINT160
+                            ? "Unlimited"
+                            : amountText(p.amount, tokenInfo(p.token, sources))
+                                  .display,
+                });
+                details.push(
+                    tokenMovedLine("Allowance token", p.token, sources),
+                );
+            }
             details.push({
                 label: "Allowance spender",
                 value: p.spender,