fix: the swap decoder reads each command's type with its router's mask (closes #535)

Each Universal Router address now carries the mask its own source reads a
command's type with: 0x1f for UniversalRouterV1, 0x3f for V1_2 and V2, 0x7f
for V2_1_1 and V2_1_2. The fixed 0x1f dropped the 0x20 bit, so
EXECUTE_SUB_PLAN (0x21) was listed as a V3 exact-out swap. A sub-plan step is
now listed as "Execute Sub-Plan (its steps are not shown)", and a Token In or
Token Out line that nothing named reads "Unknown (could not be decoded)",
since the sub-plan may name it.

Model: opus-5-5

tests/uniswap.test.js

@@ -1,8 +1,12 @@
 const { AbiCoder, Interface, solidityPacked } = require("ethers");
 const uniswap = require("../src/shared/uniswap");
 
-// A Universal Router on Ethereum Mainnet, chain id 0x1.
+// A Universal Router on Ethereum Mainnet, chain id 0x1: UniversalRouterV2,
+// which reads a command's type with the mask 0x3f.
 const ROUTER_ADDR = "0x66a9893cc07d91d95644aedd05d03f95e1dba8af";
+// Two more there, which read it with 0x1f and 0x7f.
+const ROUTER_V1_ADDR = "0xEf1c6E67703c7BD7107eed8303Fbe6EC2554BF6B";
+const ROUTER_V2_1_2_ADDR = "0x23617e59A5925b2A4Bf75d73ff6711cD0b29De85";
 const USDT_ADDR = "0xdAC17F958D2ee523a2206206994597C13D831ec7";
 const WETH_ADDR = "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2";
 const USDC_ADDR = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
@@ -864,6 +868,117 @@ describe("uniswap decoder", () => {
         );
     });
 
+    // https://git.eeqj.de/sneak/AutistMask/issues/535 \u2014 every command's type
+    // was read from its low five bits, as only UniversalRouterV1 reads it, so
+    // the later routers listed 0x21 as a V3 exact-out swap, and
+    // UniversalRouterV2_1_2 listed 0x40 as a V3 exact-in swap.
+    test.each([
+        {
+            router: "UniversalRouterV1",
+            address: ROUTER_V1_ADDR,
+            command: "0x21",
+            steps: "V3 Swap (Exact Out)",
+        },
+        {
+            router: "UniversalRouterV2",
+            address: ROUTER_ADDR,
+            command: "0x21",
+            steps: "Execute Sub-Plan (its steps are not shown)",
+        },
+        {
+            router: "UniversalRouterV2_1_2",
+            address: ROUTER_V2_1_2_ADDR,
+            command: "0x21",
+            steps: "Execute Sub-Plan (its steps are not shown)",
+        },
+        {
+            router: "UniversalRouterV1",
+            address: ROUTER_V1_ADDR,
+            command: "0x40",
+            steps: "V3 Swap (Exact In)",
+        },
+        {
+            router: "UniversalRouterV2",
+            address: ROUTER_ADDR,
+            command: "0x40",
+            steps: "V3 Swap (Exact In)",
+        },
+        {
+            router: "UniversalRouterV2_1_2",
+            address: ROUTER_V2_1_2_ADDR,
+            command: "0x40",
+            steps: "Command 0x40",
+        },
+    ])(
+        "command $command sent to $router is listed as $steps",
+        ({ address, command, steps }) => {
+            const data = buildExecute(command, ["0x"], 9999999999n);
+            const result = uniswap.decode(data, address, "0x1");
+            expect(detail(result, "Steps").value).toBe(steps);
+        },
+    );
+
+    // A sub-plan holding a V3 swap of USDT for WETH, which the decoder does
+    // not read. With the allow-revert flag (0x80) the command byte is 0xa1.
+    test.each([
+        { flag: "without", command: 0x21 },
+        { flag: "with", command: 0xa1 },
+    ])(
+        "an EXECUTE_SUB_PLAN step $flag the allow-revert flag says its steps are not shown",
+        ({ command }) => {
+            const subPlan = coder.encode(
+                ["bytes", "bytes[]"],
+                [
+                    "0x00",
+                    [
+                        encodeV3SwapExactIn(USER_ADDR, 2000000n, ONE_WETH, [
+                            USDT_ADDR,
+                            WETH_ADDR,
+                        ]),
+                    ],
+                ],
+            );
+            const data = buildExecute(
+                solidityPacked(["uint8"], [command]),
+                [subPlan],
+                9999999999n,
+            );
+            const result = uniswap.decode(data, ROUTER_ADDR, "0x1");
+            expect(result.name).toBe("Uniswap Swap");
+            expect(detail(result, "Steps").value).toBe(
+                "Execute Sub-Plan (its steps are not shown)",
+            );
+            // The sub-plan names both currencies, so the lines must not say
+            // the calldata did not.
+            expect(detail(result, "Token In").value).toBe(
+                "Unknown (could not be decoded)",
+            );
+            expect(detail(result, "Token Out").value).toBe(
+                "Unknown (could not be decoded)",
+            );
+            expect(detail(result, "Amount")).toBeUndefined();
+            expect(detail(result, "Min. received")).toBeUndefined();
+        },
+    );
+
+    // The permit names the input side; the output side is in the sub-plan.
+    test("a permit, then an EXECUTE_SUB_PLAN step, keeps the permit's token and says the rest is not shown", () => {
+        const data = buildExecute(
+            solidityPacked(["uint8", "uint8"], [0x0a, 0x21]),
+            [encodePermit2(USDT_ADDR, 1000000n, ROUTER_ADDR), "0x"],
+            9999999999n,
+        );
+        const result = uniswap.decode(data, ROUTER_ADDR, "0x1");
+        expect(detail(result, "Token In").address).toBe(USDT_ADDR);
+        expect(detail(result, "Amount").value).toBe("1.0000 USDT");
+        expect(detail(result, "Token Out").value).toBe(
+            "Unknown (could not be decoded)",
+        );
+        expect(detail(result, "Steps").value).toBe(
+            "Permit2 Permit \u2192 Execute Sub-Plan (its steps are not shown)",
+        );
+    });
+
     test("shows the deadline as a UTC date and time", () => {
         const result = uniswap.decode(FIRST_SWAP_CALLDATA, ROUTER_ADDR, "0x1");
         expect(detail(result, "Deadline").value).toBe("2026-02-27 08:25:51");