fix: a PERMIT2_PERMIT_BATCH, and a permit that cannot be read, state what they allow (closes #652)

A PERMIT2_PERMIT_BATCH was never read, and a PERMIT2_PERMIT whose input
could not be read got no lines, so the approval screen showed nothing of
the allowances either grants.

Each allowance of a batch now gets the three lines a permit whose amount
does not stand gets: Permit2 allowance, Allowance token and Allowance
spender. A permit or batch that cannot be read gets one Permit2 allowance
line reading Unknown (could not be decoded) and leaves no Amount line.
Any batch in the transaction keeps a PERMIT2_PERMIT's amount from
standing. A batch pays nobody, so it no longer adds a Paid to line.
README Transaction Decoding and the TxApproval element list match.

Model: opus-5-5

src/shared/uniswap.js

@@ -336,7 +336,8 @@ const UNNAMED_CURRENCY = "Unknown (not named in the calldata)";
 // currencies, and those commands may name one, so saying the calldata did not
 // name it would be false. The Paid to line uses it too, when a step may pay an
 // address this decoder did not read, and so do the lines for what a step
-// takes from the sender, when this decoder does not know it.
+// takes from the sender, when this decoder does not know it, and for what a
+// permit it could not read allows.
 const UNDECODED_CURRENCY = "Unknown (could not be decoded)";
 
 // The Paid to line for each token paid to the router, the swap's output or
@@ -528,6 +529,32 @@ function decodePermit2(input) {
     }
 }
 
+// Decode PERMIT2_PERMIT_BATCH (command 0x03) input bytes into the allowances
+// it grants, one for each token it names, all for its one spender, in the
+// shape decodePermit2() returns. Each release's
+// `contracts/base/Dispatcher.sol`, at the commit linked for it above, hands
+// Permit2 the batch in this shape.
+// ABI: (((address token, uint160 amount, uint48 expiration, uint48 nonce)[],
+//        address spender, uint256 sigDeadline), bytes signature)
+function decodePermit2Batch(input) {
+    try {
+        const d = coder.decode(
+            [
+                "tuple(tuple(address,uint160,uint48,uint48)[],address,uint256)",
+                "bytes",
+            ],
+            input,
+        );
+        return d[0][0].map((details) => ({
+            token: details[0],
+            amount: details[1],
+            spender: d[0][1],
+        }));
+    } catch {
+        return null;
+    }
+}
+
 // Decode BALANCE_CHECK_ERC20 (command 0x0e) input bytes. The router passes the
 // check when `owner` holds at least `minBalance` of `token`, and reads `owner`
 // as written, without map(), on every release that has the command:
@@ -1214,10 +1241,12 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // The last PERMIT2_PERMIT this decoder read before a step set the
         // input side, or null (see permitStands after the loop).
         let permit = null;
-        // Every PERMIT2_PERMIT this decoder read, before a step set the input
-        // side or after, in step order, as { token, amount, spender, step }.
-        // Each whose amount is not the Amount figure gets lines of its own
-        // (see after the PERMIT2_TRANSFER_FROM lines).
+        // Every allowance a PERMIT2_PERMIT or PERMIT2_PERMIT_BATCH grants,
+        // before a step set the input side or after, in step order, as
+        // { token, amount, spender, step }. A permit or batch whose input
+        // this decoder cannot read is one with a null token, amount and
+        // spender. Each but a permit whose amount is the Amount figure gets
+        // lines of its own (see after the PERMIT2_TRANSFER_FROM lines).
         const permits = [];
         // 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
@@ -1322,6 +1351,14 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         const spentUnread = () => {
             userPaid.push({ token: null, amount: null });
         };
+        // A PERMIT2_PERMIT or PERMIT2_PERMIT_BATCH at `step` whose input this
+        // decoder cannot read may let any spender take any amount of any
+        // token: one line says so, and there is no Amount line, whose figure
+        // may then be too low.
+        const permitUnread = (step) => {
+            permits.push({ token: null, amount: null, spender: null, step });
+            stepsUnread.push(step);
+        };
 
         // Who the steps pay, in whichever step and of whatever token.
         // MSG_SENDER is the sender. The router itself, as ADDRESS_THIS or by
@@ -1477,7 +1514,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                         permits.push({ ...p, step: i });
                         keepsRouterWeth = true;
                     } else {
-                        stepsUnread.push(i);
+                        permitUnread(i);
                     }
                     // Only a permit whose amount stands as the Amount figure
                     // names Token In (see permitStands). Every other permit,
@@ -1502,6 +1539,15 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                             beforeEveryTake: !tookBefore,
                         };
                     }
+                } else if (command === "PERMIT2_PERMIT_BATCH") {
+                    // Each allowance it grants gets the lines of a permit
+                    // whose amount does not stand. It pays nobody.
+                    const batch = decodePermit2Batch(inputs[i]);
+                    if (batch) {
+                        permits.push(...batch.map((p) => ({ ...p, step: i })));
+                    } else {
+                        permitUnread(i);
+                    }
                 } else if (command === "PERMIT2_TRANSFER_FROM") {
                     const p = decodePermit2TransferFrom(inputs[i]);
                     if (!p) {
@@ -1910,8 +1956,8 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                     }
                 } else {
                     // Any other step may pay an address this decoder does not
-                    // read: PERMIT2_PERMIT_BATCH and the NFT commands among
-                    // them, and a type the release names no command for.
+                    // read: the NFT commands among them, and a type the
+                    // release names no command for.
                     payeeUnread = true;
                     stepsUnread.push(i);
                 }
@@ -1961,17 +2007,19 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // Amount figure in place of the total, which it does only in the
         // plain shape of Uniswap's own routes: it comes before the step that
         // set the input side, it is the only PERMIT2_PERMIT in the
-        // transaction, its spender is the router, the router may not let it
-        // fail, no step before it took 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. 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 an EXECUTE_SUB_PLAN step leaves both sides unknown (below).
+        // transaction and there is no PERMIT2_PERMIT_BATCH, its spender is
+        // the router, the router may not let it fail, no step before it took
+        // 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 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 does a permit or batch
+        // whose input it cannot read (see permitUnread()). An
+        // EXECUTE_SUB_PLAN step leaves both sides unknown (below).
         const stepCommands = Array.from(
             commandsBytes,
             (b) => commands[b & commandTypeMask],
@@ -1979,6 +2027,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         const permitStands =
             permit !== null &&
             stepCommands.filter((c) => c === "PERMIT2_PERMIT").length === 1 &&
+            !stepCommands.includes("PERMIT2_PERMIT_BATCH") &&
             sameAddress(permit.spender, toAddress) &&
             !permit.allowedToFail &&
             permit.beforeEveryTake &&
@@ -2147,11 +2196,13 @@ 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, leaves no Amount figure, which may
-        // then be too low.
+        // or a token it does not know, and one in `permits`, a permit or
+        // batch it could not read, leave no Amount figure, which may then be
+        // too low.
         if (
             present(inputAmount) &&
-            spentFromSender.every((s) => present(s.token))
+            spentFromSender.every((s) => present(s.token)) &&
+            permits.every((p) => present(p.token))
         ) {
             const amount = spentText(inputAmount, inInfo);
             details.push({
@@ -2201,16 +2252,24 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             );
         }
 
-        // What each PERMIT2_PERMIT lets its spender take: its amount, its
-        // token and the spender, an address on a line of its own. Permit2's
-        // maximum is unbounded. Only a permit whose amount stands as the
-        // Amount figure (see permitStands) gets none: that line already gives
-        // its amount and Token In its token, and its spender is the router.
-        // Every other permit, one after the step that set the input side
-        // included, gets these lines, so nothing it lets anyone take goes
-        // unstated.
+        // What each allowance of a PERMIT2_PERMIT or PERMIT2_PERMIT_BATCH lets
+        // its spender take: its amount, its token and the spender, an address
+        // on a line of its own. Permit2's maximum is unbounded. Only a permit
+        // whose amount stands as the Amount figure (see permitStands) gets
+        // none: that line already gives its amount and Token In its token,
+        // and its spender is the router. Every other allowance, one after the
+        // step that set the input side included, gets these lines, so nothing
+        // it lets anyone take goes unstated. A permit or batch this decoder
+        // could not read gets one line saying so.
         for (const p of permits) {
             if (permitStands && p.step === permit.step) continue;
+            if (!present(p.token)) {
+                details.push({
+                    label: "Permit2 allowance",
+                    value: UNDECODED_CURRENCY,
+                });
+                continue;
+            }
             details.push({
                 label: "Permit2 allowance",
                 value: