fix bug in Bit255

package.json

@@ -1,6 +1,6 @@
 {
     "name": "@auxo-dev/auxo-libs",
-    "version": "0.6.1",
+    "version": "0.6.3",
     "description": "",
     "author": "",
     "license": "Apache-2.0",
@@ -17,6 +17,7 @@
     "types": "./build/types/src/index.d.ts",
     "scripts": {
         "build": "tsc --build tsconfig.esm.json tsconfig.cjs.json tsconfig.types.json && ./fix-export.sh",
+        "build:clean": "rm -rf build && rm package-lock.json && tsc --build tsconfig.esm.json tsconfig.cjs.json tsconfig.types.json && ./fix-export.sh",
         "buildw": "tsc --watch",
         "scripts": "tsc --build tsconfig.json tsconfig.cjs.json tsconfig.types.json && ./fix-export.sh && node",
         "coverage": "node --experimental-vm-modules node_modules/jest/bin/jest.js --coverage",

src/Bit255.test.ts

@@ -1,4 +1,12 @@
-import { Provable, Reducer, Scalar, SmartContract, method } from 'o1js';
+import {
+    Bool,
+    Field,
+    Provable,
+    Reducer,
+    Scalar,
+    SmartContract,
+    method,
+} from 'o1js';
 import { Bit255 } from './Bit255.js';
 
 describe('Bit255', () => {
@@ -74,4 +82,16 @@ describe('Bit255', () => {
         let converted = Bit255.fromBits(b.toBits());
         expect(b.toBigInt()).toEqual(converted.toBigInt());
     });
+
+    it('Should preserve correctness between bigint and bits', async () => {
+        let r = Field.random();
+        let bi = r.toBigInt();
+        let bits = r.toBits();
+        expect(Bit255.fromBits(bits.concat([Bool(false)])).toBigInt()).toEqual(
+            bi
+        );
+        // let b2 = Bit255.fromBigInt(b.toBigInt());
+        // expect(b.toBigInt()).toEqual(b1.toBigInt());
+        // expect(b.toBigInt()).toEqual(b2.toBigInt());
+    });
 });

src/Bit255.ts

@@ -53,16 +53,16 @@ export class Bit255 extends Struct({
     static fromBits(bits: Bool[]): Bit255 {
         if (bits.length !== 255) throw new Error('Invalid input length');
         return new Bit255({
-            head: Field.fromBits(bits.slice(0, 128)),
-            tail: Field.fromBits(bits.slice(128)),
+            head: Field.fromBits(bits.slice(127)),
+            tail: Field.fromBits(bits.slice(0, 127)),
         });
     }
 
     static toBits(b: Bit255): Bool[] {
-        return b.head
+        return b.tail
             .toBits()
-            .slice(0, 128)
-            .concat(b.tail.toBits().slice(0, 127));
+            .slice(0, 127)
+            .concat(b.head.toBits().slice(0, 128));
     }
 
     static fromBigInt(i: bigint): Bit255 {