feat: expose getL2ToL1Membership on the pxe (#11215)

This PR adds a new API to the PXE to calculate the membership witness
for an L2 to L1 message by forwarding the request to a node (this
obviously leaks privacy). This API is necessary in order to complete a
withdrawal back to L1.

yarn-project/aztec.js/src/index.ts

@@ -46,6 +46,7 @@ export {
   type L2AmountClaimWithRecipient,
   type L2Claim,
   type WrappedFieldLike,
+  type IntentAction,
 } from './utils/index.js';
 
 export { NoteSelector } from '@aztec/foundation/abi';

yarn-project/aztec.js/src/wallet/base_wallet.ts

@@ -211,4 +211,7 @@ export abstract class BaseWallet implements Wallet {
   ): Promise<[bigint, SiblingPath<typeof L1_TO_L2_MSG_TREE_HEIGHT>]> {
     return this.pxe.getL1ToL2MembershipWitness(contractAddress, messageHash, secret);
   }
+  getL2ToL1MembershipWitness(blockNumber: number, l2Tol1Message: Fr): Promise<[bigint, SiblingPath<number>]> {
+    return this.pxe.getL2ToL1MembershipWitness(blockNumber, l2Tol1Message);
+  }
 }

yarn-project/circuit-types/src/interfaces/pxe.test.ts

@@ -200,6 +200,11 @@ describe('PXESchema', () => {
     expect(result).toEqual([expect.any(BigInt), expect.any(SiblingPath)]);
   });
 
+  it('getL2ToL1MembershipWitness', async () => {
+    const result = await context.client.getL2ToL1MembershipWitness(42, Fr.random());
+    expect(result).toEqual([expect.any(BigInt), expect.any(SiblingPath)]);
+  });
+
   it('addNote', async () => {
     await context.client.addNote(ExtendedNote.random(), address);
   });
@@ -423,6 +428,11 @@ class MockPXE implements PXE {
     expect(secret).toBeInstanceOf(Fr);
     return Promise.resolve([1n, SiblingPath.random(L1_TO_L2_MSG_TREE_HEIGHT)]);
   }
+  getL2ToL1MembershipWitness(blockNumber: number, l2Tol1Message: Fr): Promise<[bigint, SiblingPath<number>]> {
+    expect(typeof blockNumber).toEqual('number');
+    expect(l2Tol1Message).toBeInstanceOf(Fr);
+    return Promise.resolve([1n, SiblingPath.random<number>(4)]);
+  }
   addNote(note: ExtendedNote, scope?: AztecAddress | undefined): Promise<void> {
     expect(note).toBeInstanceOf(ExtendedNote);
     expect(scope).toEqual(this.address);

yarn-project/circuit-types/src/interfaces/pxe.ts

@@ -252,6 +252,14 @@ export interface PXE {
     secret: Fr,
   ): Promise<[bigint, SiblingPath<typeof L1_TO_L2_MSG_TREE_HEIGHT>]>;
 
+  /**
+   * Gets the membership witness for a message that was emitted at a particular block
+   * @param blockNumber - The block number in which to search for the message
+   * @param l2Tol1Message - The message to search for
+   * @returns The membership witness for the message
+   */
+  getL2ToL1MembershipWitness(blockNumber: number, l2Tol1Message: Fr): Promise<[bigint, SiblingPath<number>]>;
+
   /**
    * Adds a note to the database.
    * @throws If the note hash of the note doesn't exist in the tree.
@@ -488,6 +496,10 @@ export const PXESchema: ApiSchemaFor<PXE> = {
     .function()
     .args(schemas.AztecAddress, schemas.Fr, schemas.Fr)
     .returns(z.tuple([schemas.BigInt, SiblingPath.schemaFor(L1_TO_L2_MSG_TREE_HEIGHT)])),
+  getL2ToL1MembershipWitness: z
+    .function()
+    .args(z.number(), schemas.Fr)
+    .returns(z.tuple([schemas.BigInt, SiblingPath.schema])),
   addNote: z.function().args(ExtendedNote.schema, optional(schemas.AztecAddress)).returns(z.void()),
   addNullifiedNote: z.function().args(ExtendedNote.schema).returns(z.void()),
   getBlock: z

yarn-project/pxe/src/pxe_service/pxe_service.ts

@@ -307,6 +307,10 @@ export class PXEService implements PXE {
     return await getNonNullifiedL1ToL2MessageWitness(this.node, contractAddress, messageHash, secret);
   }
 
+  public getL2ToL1MembershipWitness(blockNumber: number, l2Tol1Message: Fr): Promise<[bigint, SiblingPath<number>]> {
+    return this.node.getL2ToL1MessageMembershipWitness(blockNumber, l2Tol1Message);
+  }
+
   public async addNote(note: ExtendedNote, scope?: AztecAddress) {
     const owner = await this.db.getCompleteAddress(note.owner);
     if (!owner) {