From 433b9ebdb505b21bef40c174e4feec0e6ca211e8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Bene=C5=A1?= <janbenes1234@gmail.com>
Date: Thu, 1 Feb 2024 14:05:40 +0100
Subject: [PATCH] refactor: `toFields()`/`fromFields(...)` methods in more
 classes (#4335)

Partially fixes #4332

The goal of this PR was to progress on nuking
yarn-project/acir-simulator/src/acvm/serialize.ts and move it to the
individual classes to then be able to easily test it in the classes
tests and improve readability.

I didn't fully tackle the issue in this one because it was all getting
too big.
---
 .../acir-simulator/src/acvm/deserialize.ts    |   4 +-
 .../acir-simulator/src/acvm/oracle/oracle.ts  |  16 +-
 .../src/acvm/oracle/typed_oracle.ts           |  33 ++--
 .../acir-simulator/src/acvm/serialize.ts      | 154 +-----------------
 .../src/client/client_execution_context.ts    |  14 +-
 .../src/client/private_execution.test.ts      |  14 +-
 .../acir-simulator/src/public/index.test.ts   |   9 +-
 .../src/public/public_execution_context.ts    |  10 +-
 yarn-project/circuits.js/src/abis/abis.ts     |   4 +-
 .../call_stack_item.test.ts.snap              |  44 +++++
 .../circuits.js/src/structs/call_context.ts   |   6 +-
 .../src/structs/call_stack_item.test.ts       |  28 ++++
 .../src/structs/call_stack_item.ts            |  23 ++-
 .../structs/contract_deployment_data.test.ts  |  17 ++
 .../src/structs/contract_deployment_data.ts   |  94 +++++++++++
 .../circuits.js/src/structs/function_data.ts  |  19 ++-
 .../src/structs/global_variables.ts           |  10 +-
 .../circuits.js/src/structs/header.test.ts    |   4 +-
 .../circuits.js/src/structs/header.ts         |  35 ++--
 yarn-project/circuits.js/src/structs/index.ts |   1 +
 .../src/structs/partial_state_reference.ts    |  24 ++-
 .../private_circuit_public_inputs.test.ts     |  15 ++
 .../structs/private_circuit_public_inputs.ts  |  44 ++++-
 .../rollup/append_only_tree_snapshot.ts       |  10 +-
 .../src/structs/state_reference.ts            |  13 +-
 .../circuits.js/src/structs/tx_context.ts     |  75 +--------
 .../foundation/src/serialize/serialize.ts     |  40 +++++
 .../src/type_conversion.test.ts               |   2 +-
 .../pxe/src/simulator_oracle/index.ts         |   6 +-
 .../src/simulator/public_executor.ts          |   6 +-
 30 files changed, 434 insertions(+), 340 deletions(-)
 create mode 100644 yarn-project/circuits.js/src/structs/__snapshots__/call_stack_item.test.ts.snap
 create mode 100644 yarn-project/circuits.js/src/structs/call_stack_item.test.ts
 create mode 100644 yarn-project/circuits.js/src/structs/contract_deployment_data.test.ts
 create mode 100644 yarn-project/circuits.js/src/structs/contract_deployment_data.ts

diff --git a/yarn-project/acir-simulator/src/acvm/deserialize.ts b/yarn-project/acir-simulator/src/acvm/deserialize.ts
index a49f060e2e7..1c4aa93ec26 100644
--- a/yarn-project/acir-simulator/src/acvm/deserialize.ts
+++ b/yarn-project/acir-simulator/src/acvm/deserialize.ts
@@ -101,7 +101,7 @@ export function extractPrivateCircuitPublicInputs(
   const encryptedLogPreimagesLength = witnessReader.readField();
   const unencryptedLogPreimagesLength = witnessReader.readField();
 
-  const header = Header.fromFieldArray(witnessReader.readFieldArray(HEADER_LENGTH));
+  const header = Header.fromFields(witnessReader.readFieldArray(HEADER_LENGTH));
 
   const contractDeploymentData = new ContractDeploymentData(
     new Point(witnessReader.readField(), witnessReader.readField()),
@@ -176,7 +176,7 @@ export function extractPublicCircuitPublicInputs(partialWitness: ACVMWitness, ac
   const unencryptedLogsHash = witnessReader.readFieldArray(NUM_FIELDS_PER_SHA256);
   const unencryptedLogPreimagesLength = witnessReader.readField();
 
-  const header = Header.fromFieldArray(witnessReader.readFieldArray(HEADER_LENGTH));
+  const header = Header.fromFields(witnessReader.readFieldArray(HEADER_LENGTH));
 
   const proverAddress = AztecAddress.fromField(witnessReader.readField());
 
diff --git a/yarn-project/acir-simulator/src/acvm/oracle/oracle.ts b/yarn-project/acir-simulator/src/acvm/oracle/oracle.ts
index 22d3d9dd04c..984d16c7992 100644
--- a/yarn-project/acir-simulator/src/acvm/oracle/oracle.ts
+++ b/yarn-project/acir-simulator/src/acvm/oracle/oracle.ts
@@ -8,13 +8,7 @@ import { createDebugLogger } from '@aztec/foundation/log';
 
 import { ACVMField } from '../acvm_types.js';
 import { frToNumber, fromACVMField } from '../deserialize.js';
-import {
-  toACVMField,
-  toACVMHeader,
-  toAcvmCallPrivateStackItem,
-  toAcvmEnqueuePublicFunctionResult,
-  toAcvmL1ToL2MessageLoadOracleInputs,
-} from '../serialize.js';
+import { toACVMField, toAcvmEnqueuePublicFunctionResult } from '../serialize.js';
 import { acvmFieldMessageToString, oracleDebugCallToFormattedStr } from './debug.js';
 import { TypedOracle } from './typed_oracle.js';
 
@@ -132,7 +126,7 @@ export class Oracle {
     if (!header) {
       throw new Error(`Block header not found for block ${parsedBlockNumber}.`);
     }
-    return toACVMHeader(header);
+    return header.toFields().map(toACVMField);
   }
 
   async getAuthWitness([messageHash]: ACVMField[]): Promise<ACVMField[]> {
@@ -226,8 +220,8 @@ export class Oracle {
   }
 
   async getL1ToL2Message([msgKey]: ACVMField[]): Promise<ACVMField[]> {
-    const { ...message } = await this.typedOracle.getL1ToL2Message(fromACVMField(msgKey));
-    return toAcvmL1ToL2MessageLoadOracleInputs(message);
+    const message = await this.typedOracle.getL1ToL2Message(fromACVMField(msgKey));
+    return message.toFields().map(toACVMField);
   }
 
   async getPortalContractAddress([aztecAddress]: ACVMField[]): Promise<ACVMField> {
@@ -297,7 +291,7 @@ export class Oracle {
       fromACVMField(argsHash),
       frToNumber(fromACVMField(sideffectCounter)),
     );
-    return toAcvmCallPrivateStackItem(callStackItem);
+    return callStackItem.toFields().map(toACVMField);
   }
 
   async callPublicFunction(
diff --git a/yarn-project/acir-simulator/src/acvm/oracle/typed_oracle.ts b/yarn-project/acir-simulator/src/acvm/oracle/typed_oracle.ts
index ffa9ac1fbfc..f4c58c9d33d 100644
--- a/yarn-project/acir-simulator/src/acvm/oracle/typed_oracle.ts
+++ b/yarn-project/acir-simulator/src/acvm/oracle/typed_oracle.ts
@@ -48,23 +48,22 @@ export interface NoteData {
   index?: bigint;
 }
 
-/**
- * The data for L1 to L2 Messages provided by other data sources.
- */
-export interface MessageLoadOracleInputs {
-  /**
-   * An collapsed array of fields containing all of the l1 to l2 message components.
-   * `l1ToL2Message.toFieldArray()` -\> [sender, chainId, recipient, version, content, secretHash, deadline, fee]
-   */
-  message: Fr[];
-  /**
-   * The path in the merkle tree to the message.
-   */
-  siblingPath: Fr[];
-  /**
-   * The index of the message commitment in the merkle tree.
-   */
-  index: bigint;
+export class MessageLoadOracleInputs {
+  constructor(
+    /**
+     * An collapsed array of fields containing all of the l1 to l2 message components.
+     * `l1ToL2Message.toFieldArray()` -\> [sender, chainId, recipient, version, content, secretHash, deadline, fee]
+     */
+    public message: Fr[],
+    /** The index of the message commitment in the merkle tree. */
+    public index: bigint,
+    /** The path in the merkle tree to the message. */
+    public siblingPath: Fr[],
+  ) {}
+
+  toFields(): Fr[] {
+    return [...this.message, new Fr(this.index), ...this.siblingPath];
+  }
 }
 
 /**
diff --git a/yarn-project/acir-simulator/src/acvm/serialize.ts b/yarn-project/acir-simulator/src/acvm/serialize.ts
index c2c7440d8a9..28ca4b3e27f 100644
--- a/yarn-project/acir-simulator/src/acvm/serialize.ts
+++ b/yarn-project/acir-simulator/src/acvm/serialize.ts
@@ -1,19 +1,9 @@
-import {
-  CallContext,
-  ContractDeploymentData,
-  FunctionData,
-  GlobalVariables,
-  Header,
-  PrivateCallStackItem,
-  PrivateCircuitPublicInputs,
-  PublicCallRequest,
-} from '@aztec/circuits.js';
+import { PublicCallRequest } from '@aztec/circuits.js';
 import { AztecAddress } from '@aztec/foundation/aztec-address';
 import { EthAddress } from '@aztec/foundation/eth-address';
 import { Fr } from '@aztec/foundation/fields';
 
 import { ACVMField } from './acvm_types.js';
-import { MessageLoadOracleInputs } from './oracle/typed_oracle.js';
 
 /**
  * Adapts the buffer to the field size.
@@ -53,125 +43,6 @@ export function toACVMField(
 // Utilities to write TS classes to ACVM Field arrays
 // In the order that the ACVM expects them
 
-/**
- * Converts a function data to ACVM fields.
- * @param functionData - The function data to convert.
- * @returns The ACVM fields.
- */
-export function toACVMFunctionData(functionData: FunctionData): ACVMField[] {
-  return [
-    toACVMField(functionData.selector.toBuffer()),
-    toACVMField(functionData.isInternal),
-    toACVMField(functionData.isPrivate),
-    toACVMField(functionData.isConstructor),
-  ];
-}
-
-/**
- * Converts a call context to ACVM fields.
- * @param callContext - The call context to convert.
- * @returns The ACVM fields.
- */
-export function toACVMCallContext(callContext: CallContext): ACVMField[] {
-  return [
-    toACVMField(callContext.msgSender),
-    toACVMField(callContext.storageContractAddress),
-    toACVMField(callContext.portalContractAddress),
-    toACVMField(callContext.functionSelector.toField()),
-    toACVMField(callContext.isDelegateCall),
-    toACVMField(callContext.isStaticCall),
-    toACVMField(callContext.isContractDeployment),
-    toACVMField(callContext.startSideEffectCounter),
-  ];
-}
-
-/**
- * Converts a contract deployment data to ACVM fields.
- * @param contractDeploymentData - The contract deployment data to convert.
- * @returns The ACVM fields.
- */
-export function toACVMContractDeploymentData(contractDeploymentData: ContractDeploymentData): ACVMField[] {
-  return [
-    toACVMField(contractDeploymentData.publicKey.x),
-    toACVMField(contractDeploymentData.publicKey.y),
-    toACVMField(contractDeploymentData.initializationHash),
-    toACVMField(contractDeploymentData.contractClassId),
-    toACVMField(contractDeploymentData.contractAddressSalt),
-    toACVMField(contractDeploymentData.portalContractAddress),
-  ];
-}
-
-/**
- * Converts a block header into ACVM fields.
- * @param header - The block header object to convert.
- * @returns The ACVM fields.
- */
-export function toACVMHeader(header: Header): ACVMField[] {
-  return header.toFieldArray().map(toACVMField);
-}
-
-/**
- * Converts global variables into ACVM fields
- * @param globalVariables - The global variables object to convert.
- * @returns The ACVM fields
- */
-export function toACVMGlobalVariables(globalVariables: GlobalVariables): ACVMField[] {
-  return [
-    toACVMField(globalVariables.chainId),
-    toACVMField(globalVariables.version),
-    toACVMField(globalVariables.blockNumber),
-    toACVMField(globalVariables.timestamp),
-  ];
-}
-
-/**
- * Converts the public inputs structure to ACVM fields.
- * @param publicInputs - The public inputs to convert.
- * @returns The ACVM fields.
- */
-export function toACVMPublicInputs(publicInputs: PrivateCircuitPublicInputs): ACVMField[] {
-  return [
-    ...toACVMCallContext(publicInputs.callContext),
-    toACVMField(publicInputs.argsHash),
-
-    ...publicInputs.returnValues.map(toACVMField),
-    ...publicInputs.readRequests.flatMap(x => x.toFields()).map(toACVMField),
-    ...publicInputs.nullifierKeyValidationRequests.flatMap(x => x.toFields()).map(toACVMField),
-    ...publicInputs.newCommitments.flatMap(x => x.toFields()).map(toACVMField),
-    ...publicInputs.newNullifiers.flatMap(x => x.toFields()).map(toACVMField),
-    ...publicInputs.privateCallStackHashes.map(toACVMField),
-    ...publicInputs.publicCallStackHashes.map(toACVMField),
-    ...publicInputs.newL2ToL1Msgs.map(toACVMField),
-    toACVMField(publicInputs.endSideEffectCounter),
-    ...publicInputs.encryptedLogsHash.map(toACVMField),
-    ...publicInputs.unencryptedLogsHash.map(toACVMField),
-
-    toACVMField(publicInputs.encryptedLogPreimagesLength),
-    toACVMField(publicInputs.unencryptedLogPreimagesLength),
-
-    ...toACVMHeader(publicInputs.historicalHeader),
-
-    ...toACVMContractDeploymentData(publicInputs.contractDeploymentData),
-
-    toACVMField(publicInputs.chainId),
-    toACVMField(publicInputs.version),
-  ];
-}
-
-/**
- * Converts a private call stack item to ACVM fields.
- * @param item - The private call stack item to convert.
- * @returns The ACVM fields.
- */
-export function toAcvmCallPrivateStackItem(item: PrivateCallStackItem): ACVMField[] {
-  return [
-    toACVMField(item.contractAddress),
-    ...toACVMFunctionData(item.functionData),
-    ...toACVMPublicInputs(item.publicInputs),
-    toACVMField(item.isExecutionRequest),
-  ];
-}
-
 /**
  * Converts a public call stack item with the request for executing a public function to
  * a set of ACVM fields accepted by the enqueue_public_function_call_oracle Aztec.nr function.
@@ -182,24 +53,11 @@ export function toAcvmCallPrivateStackItem(item: PrivateCallStackItem): ACVMFiel
  */
 export function toAcvmEnqueuePublicFunctionResult(item: PublicCallRequest): ACVMField[] {
   return [
-    toACVMField(item.contractAddress),
-    ...toACVMFunctionData(item.functionData),
-    ...toACVMCallContext(item.callContext),
-    toACVMField(item.getArgsHash()),
-  ];
-}
-
-/**
- * Converts the result of loading messages to ACVM fields.
- * @param messageLoadOracleInputs - The result of loading messages to convert.
- * @returns The Message Oracle Fields.
- */
-export function toAcvmL1ToL2MessageLoadOracleInputs(messageLoadOracleInputs: MessageLoadOracleInputs): ACVMField[] {
-  return [
-    ...messageLoadOracleInputs.message.map(f => toACVMField(f)),
-    toACVMField(messageLoadOracleInputs.index),
-    ...messageLoadOracleInputs.siblingPath.map(f => toACVMField(f)),
-  ];
+    item.contractAddress.toField(),
+    ...item.functionData.toFields(),
+    ...item.callContext.toFields(),
+    item.getArgsHash(),
+  ].map(toACVMField);
 }
 
 /**
diff --git a/yarn-project/acir-simulator/src/client/client_execution_context.ts b/yarn-project/acir-simulator/src/client/client_execution_context.ts
index f3d684f4ef0..27afde14d26 100644
--- a/yarn-project/acir-simulator/src/client/client_execution_context.ts
+++ b/yarn-project/acir-simulator/src/client/client_execution_context.ts
@@ -17,13 +17,7 @@ import { AztecAddress } from '@aztec/foundation/aztec-address';
 import { Fr, Point } from '@aztec/foundation/fields';
 import { createDebugLogger } from '@aztec/foundation/log';
 
-import {
-  NoteData,
-  toACVMCallContext,
-  toACVMContractDeploymentData,
-  toACVMHeader,
-  toACVMWitness,
-} from '../acvm/index.js';
+import { NoteData, toACVMWitness } from '../acvm/index.js';
 import { PackedArgsCache } from '../common/packed_args_cache.js';
 import { DBOracle } from './db_oracle.js';
 import { ExecutionNoteCache } from './execution_note_cache.js';
@@ -96,9 +90,9 @@ export class ClientExecutionContext extends ViewDataOracle {
     }
 
     const fields = [
-      ...toACVMCallContext(this.callContext),
-      ...toACVMHeader(this.historicalHeader),
-      ...toACVMContractDeploymentData(contractDeploymentData),
+      ...this.callContext.toFields(),
+      ...this.historicalHeader.toFields(),
+      ...contractDeploymentData.toFields(),
 
       this.txContext.chainId,
       this.txContext.version,
diff --git a/yarn-project/acir-simulator/src/client/private_execution.test.ts b/yarn-project/acir-simulator/src/client/private_execution.test.ts
index 0587f3ec4dd..b3ace37240b 100644
--- a/yarn-project/acir-simulator/src/client/private_execution.test.ts
+++ b/yarn-project/acir-simulator/src/client/private_execution.test.ts
@@ -56,7 +56,7 @@ import { jest } from '@jest/globals';
 import { MockProxy, mock } from 'jest-mock-extended';
 import { getFunctionSelector } from 'viem';
 
-import { KeyPair } from '../acvm/index.js';
+import { KeyPair, MessageLoadOracleInputs } from '../acvm/index.js';
 import { buildL1ToL2Message } from '../test/utils.js';
 import { computeSlotForMapping } from '../utils.js';
 import { DBOracle } from './db_oracle.js';
@@ -544,11 +544,13 @@ describe('Private Execution test suite', () => {
       const mockOracles = async () => {
         const tree = await insertLeaves([messageKey ?? preimage.hash()], 'l1ToL2Messages');
         oracle.getL1ToL2Message.mockImplementation(async () => {
-          return Promise.resolve({
-            message: preimage.toFieldArray(),
-            index: 0n,
-            siblingPath: (await tree.getSiblingPath(0n, false)).toFieldArray(),
-          });
+          return Promise.resolve(
+            new MessageLoadOracleInputs(
+              preimage.toFieldArray(),
+              0n,
+              (await tree.getSiblingPath(0n, false)).toFieldArray(),
+            ),
+          );
         });
       };
 
diff --git a/yarn-project/acir-simulator/src/public/index.test.ts b/yarn-project/acir-simulator/src/public/index.test.ts
index dde71adb1ea..4d7fdb81c92 100644
--- a/yarn-project/acir-simulator/src/public/index.test.ts
+++ b/yarn-project/acir-simulator/src/public/index.test.ts
@@ -21,6 +21,7 @@ import { MockProxy, mock } from 'jest-mock-extended';
 import { type MemDown, default as memdown } from 'memdown';
 import { getFunctionSelector } from 'viem';
 
+import { MessageLoadOracleInputs } from '../index.js';
 import { buildL1ToL2Message } from '../test/utils.js';
 import { computeSlotForMapping } from '../utils.js';
 import { CommitmentsDB, PublicContractsDB, PublicStateDB } from './db.js';
@@ -459,12 +460,8 @@ describe('ACIR public execution simulator', () => {
         for (const sibling of siblingPath) {
           root = Fr.fromBuffer(pedersenHash([root.toBuffer(), sibling.toBuffer()]));
         }
-        commitmentsDb.getL1ToL2Message.mockImplementation(async () => {
-          return await Promise.resolve({
-            message: preimage.toFieldArray(),
-            index: 0n,
-            siblingPath,
-          });
+        commitmentsDb.getL1ToL2Message.mockImplementation(() => {
+          return Promise.resolve(new MessageLoadOracleInputs(preimage.toFieldArray(), 0n, siblingPath));
         });
 
         return new AppendOnlyTreeSnapshot(
diff --git a/yarn-project/acir-simulator/src/public/public_execution_context.ts b/yarn-project/acir-simulator/src/public/public_execution_context.ts
index 5ed036b1413..1c275fae334 100644
--- a/yarn-project/acir-simulator/src/public/public_execution_context.ts
+++ b/yarn-project/acir-simulator/src/public/public_execution_context.ts
@@ -5,7 +5,7 @@ import { EthAddress } from '@aztec/foundation/eth-address';
 import { Fr } from '@aztec/foundation/fields';
 import { createDebugLogger } from '@aztec/foundation/log';
 
-import { TypedOracle, toACVMCallContext, toACVMGlobalVariables, toACVMHeader, toACVMWitness } from '../acvm/index.js';
+import { TypedOracle, toACVMWitness } from '../acvm/index.js';
 import { PackedArgsCache, SideEffectCounter } from '../common/index.js';
 import { CommitmentsDB, PublicContractsDB, PublicStateDB } from './db.js';
 import { PublicExecution, PublicExecutionResult } from './execution.js';
@@ -49,13 +49,7 @@ export class PublicExecutionContext extends TypedOracle {
    */
   public getInitialWitness(witnessStartIndex = 0) {
     const { callContext, args } = this.execution;
-    const fields = [
-      ...toACVMCallContext(callContext),
-      ...toACVMHeader(this.header),
-      ...toACVMGlobalVariables(this.globalVariables),
-
-      ...args,
-    ];
+    const fields = [...callContext.toFields(), ...this.header.toFields(), ...this.globalVariables.toFields(), ...args];
 
     return toACVMWitness(witnessStartIndex, fields);
   }
diff --git a/yarn-project/circuits.js/src/abis/abis.ts b/yarn-project/circuits.js/src/abis/abis.ts
index 8f346fbd79e..003829def1b 100644
--- a/yarn-project/circuits.js/src/abis/abis.ts
+++ b/yarn-project/circuits.js/src/abis/abis.ts
@@ -397,7 +397,7 @@ function computePrivateInputsHash(input: PrivateCircuitPublicInputs) {
     ...input.unencryptedLogsHash.map(fr => fr.toBuffer()),
     input.encryptedLogPreimagesLength.toBuffer(),
     input.unencryptedLogPreimagesLength.toBuffer(),
-    ...(input.historicalHeader.toFieldArray().map(fr => fr.toBuffer()) as Buffer[]),
+    ...(input.historicalHeader.toFields().map(fr => fr.toBuffer()) as Buffer[]),
     computeContractDeploymentDataHash(input.contractDeploymentData).toBuffer(),
     input.chainId.toBuffer(),
     input.version.toBuffer(),
@@ -463,7 +463,7 @@ export function computePublicInputsHash(input: PublicCircuitPublicInputs) {
     ...input.newL2ToL1Msgs.map(fr => fr.toBuffer()),
     ...input.unencryptedLogsHash.map(fr => fr.toBuffer()),
     input.unencryptedLogPreimagesLength.toBuffer(),
-    ...input.historicalHeader.toFieldArray().map(fr => fr.toBuffer()),
+    ...input.historicalHeader.toFields().map(fr => fr.toBuffer()),
     input.proverAddress.toBuffer(),
   ];
   if (toHash.length != PUBLIC_CIRCUIT_PUBLIC_INPUTS_HASH_INPUT_LENGTH) {
diff --git a/yarn-project/circuits.js/src/structs/__snapshots__/call_stack_item.test.ts.snap b/yarn-project/circuits.js/src/structs/__snapshots__/call_stack_item.test.ts.snap
new file mode 100644
index 00000000000..d54ec645a35
--- /dev/null
+++ b/yarn-project/circuits.js/src/structs/__snapshots__/call_stack_item.test.ts.snap
@@ -0,0 +1,44 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`PrivateCallStackItem computes hash 1`] = `
+Fr {
+  "asBigInt": 20211835094457188239301134546342553663959029760227448898294272588084026667910n,
+  "asBuffer": {
+    "data": [
+      44,
+      175,
+      126,
+      70,
+      125,
+      139,
+      43,
+      118,
+      26,
+      81,
+      126,
+      221,
+      198,
+      219,
+      65,
+      196,
+      232,
+      191,
+      214,
+      222,
+      18,
+      149,
+      88,
+      100,
+      79,
+      28,
+      235,
+      175,
+      176,
+      129,
+      243,
+      134,
+    ],
+    "type": "Buffer",
+  },
+}
+`;
diff --git a/yarn-project/circuits.js/src/structs/call_context.ts b/yarn-project/circuits.js/src/structs/call_context.ts
index 5f35bced17d..3640040718d 100644
--- a/yarn-project/circuits.js/src/structs/call_context.ts
+++ b/yarn-project/circuits.js/src/structs/call_context.ts
@@ -1,6 +1,6 @@
 import { AztecAddress } from '@aztec/foundation/aztec-address';
 import { EthAddress } from '@aztec/foundation/eth-address';
-import { BufferReader, FieldReader, serializeToBuffer } from '@aztec/foundation/serialize';
+import { BufferReader, FieldReader, serializeToBuffer, serializeToFieldArray } from '@aztec/foundation/serialize';
 import { FieldsOf } from '@aztec/foundation/types';
 
 import { Fr, FunctionSelector } from './index.js';
@@ -107,6 +107,10 @@ export class CallContext {
     return serializeToBuffer(...CallContext.getFields(this));
   }
 
+  toFields(): Fr[] {
+    return serializeToFieldArray(...CallContext.getFields(this));
+  }
+
   /**
    * Deserialize this from a buffer.
    * @param buffer - The bufferable type from which to deserialize.
diff --git a/yarn-project/circuits.js/src/structs/call_stack_item.test.ts b/yarn-project/circuits.js/src/structs/call_stack_item.test.ts
new file mode 100644
index 00000000000..0a483a35699
--- /dev/null
+++ b/yarn-project/circuits.js/src/structs/call_stack_item.test.ts
@@ -0,0 +1,28 @@
+import { makePrivateCallStackItem } from '../tests/factories.js';
+import { PrivateCallStackItem } from './call_stack_item.js';
+
+describe('PrivateCallStackItem', () => {
+  it('serializes to buffer and deserializes it back', () => {
+    const randomInt = Math.floor(Math.random() * 1000);
+    const expected = makePrivateCallStackItem(randomInt);
+    const buffer = expected.toBuffer();
+    const res = PrivateCallStackItem.fromBuffer(buffer);
+    expect(res).toEqual(expected);
+  });
+
+  it('serializes to field array and deserializes it back', () => {
+    const randomInt = Math.floor(Math.random() * 1000);
+    const expected = makePrivateCallStackItem(randomInt);
+
+    const fieldArray = expected.toFields();
+    const res = PrivateCallStackItem.fromFields(fieldArray);
+    expect(res).toEqual(expected);
+  });
+
+  it('computes hash', () => {
+    const seed = 9870243;
+    const PrivateCallStackItem = makePrivateCallStackItem(seed);
+    const hash = PrivateCallStackItem.hash();
+    expect(hash).toMatchSnapshot();
+  });
+});
diff --git a/yarn-project/circuits.js/src/structs/call_stack_item.ts b/yarn-project/circuits.js/src/structs/call_stack_item.ts
index 4752238d7bc..397b1654289 100644
--- a/yarn-project/circuits.js/src/structs/call_stack_item.ts
+++ b/yarn-project/circuits.js/src/structs/call_stack_item.ts
@@ -1,6 +1,6 @@
 import { AztecAddress } from '@aztec/foundation/aztec-address';
 import { Fr } from '@aztec/foundation/fields';
-import { BufferReader, serializeToBuffer } from '@aztec/foundation/serialize';
+import { BufferReader, FieldReader, serializeToBuffer } from '@aztec/foundation/serialize';
 
 import { computePrivateCallStackItemHash, computePublicCallStackItemHash } from '../abis/abis.js';
 import { CallRequest, CallerContext } from './call_request.js';
@@ -10,7 +10,6 @@ import { PublicCircuitPublicInputs } from './public_circuit_public_inputs.js';
 
 /**
  * Call stack item on a private call.
- * @see cpp/src/aztec3/circuits/abis/call_stack_item.hpp.
  */
 export class PrivateCallStackItem {
   constructor(
@@ -40,6 +39,15 @@ export class PrivateCallStackItem {
     return serializeToBuffer(this.contractAddress, this.functionData, this.publicInputs, this.isExecutionRequest);
   }
 
+  toFields(): Fr[] {
+    return [
+      this.contractAddress.toField(),
+      ...this.functionData.toFields(),
+      ...this.publicInputs.toFields(),
+      new Fr(this.isExecutionRequest),
+    ];
+  }
+
   /**
    * Deserializes from a buffer or reader.
    * @param buffer - Buffer or reader to read from.
@@ -55,6 +63,17 @@ export class PrivateCallStackItem {
     );
   }
 
+  static fromFields(fields: Fr[] | FieldReader): PrivateCallStackItem {
+    const reader = FieldReader.asReader(fields);
+
+    const contractAddress = AztecAddress.fromFields(reader);
+    const functionData = FunctionData.fromFields(reader);
+    const publicInputs = PrivateCircuitPublicInputs.fromFields(reader);
+    const isExecutionRequest = reader.readBoolean();
+
+    return new PrivateCallStackItem(contractAddress, functionData, publicInputs, isExecutionRequest);
+  }
+
   /**
    * Returns a new instance of PrivateCallStackItem with zero contract address, function data and public inputs.
    * @returns A new instance of PrivateCallStackItem with zero contract address, function data and public inputs.
diff --git a/yarn-project/circuits.js/src/structs/contract_deployment_data.test.ts b/yarn-project/circuits.js/src/structs/contract_deployment_data.test.ts
new file mode 100644
index 00000000000..40fa0173a03
--- /dev/null
+++ b/yarn-project/circuits.js/src/structs/contract_deployment_data.test.ts
@@ -0,0 +1,17 @@
+import { makeContractDeploymentData } from '../tests/factories.js';
+import { ContractDeploymentData } from './contract_deployment_data.js';
+
+describe('ContractDeploymentData', () => {
+  it(`serializes to buffer and deserializes it back`, () => {
+    const expected = makeContractDeploymentData(1);
+    const buffer = expected.toBuffer();
+    const res = ContractDeploymentData.fromBuffer(buffer);
+    expect(res).toEqual(expected);
+    expect(res.isEmpty()).toBe(false);
+  });
+
+  it(`initializes an empty ContractDeploymentData`, () => {
+    const target = ContractDeploymentData.empty();
+    expect(target.isEmpty()).toBe(true);
+  });
+});
diff --git a/yarn-project/circuits.js/src/structs/contract_deployment_data.ts b/yarn-project/circuits.js/src/structs/contract_deployment_data.ts
new file mode 100644
index 00000000000..d99d15044a0
--- /dev/null
+++ b/yarn-project/circuits.js/src/structs/contract_deployment_data.ts
@@ -0,0 +1,94 @@
+import { BufferReader, FieldReader, serializeToBuffer } from '@aztec/foundation/serialize';
+
+import { EthAddress, Fr, Point, PublicKey } from '../index.js';
+
+/**
+ * Contract deployment data in a TxContext
+ * Not to be confused with NewContractData.
+ */
+export class ContractDeploymentData {
+  constructor(
+    /** Public key of the contract. */
+    public publicKey: PublicKey,
+    /** Hash of the initialization payload. */
+    public initializationHash: Fr,
+    /** Contract class identifier. */
+    public contractClassId: Fr,
+    /** Contract address salt (used when deriving a contract address). */
+    public contractAddressSalt: Fr,
+    /** Ethereum address of the portal contract on L1. */
+    public portalContractAddress: EthAddress,
+  ) {}
+
+  toBuffer() {
+    return serializeToBuffer(
+      this.publicKey,
+      this.initializationHash,
+      this.contractClassId,
+      this.contractAddressSalt,
+      this.portalContractAddress,
+    );
+  }
+
+  toFields(): Fr[] {
+    return [
+      ...this.publicKey.toFields(),
+      this.initializationHash,
+      this.contractClassId,
+      this.contractAddressSalt,
+      this.portalContractAddress.toField(),
+    ];
+  }
+
+  /**
+   * Returns an empty ContractDeploymentData.
+   * @returns The empty ContractDeploymentData.
+   */
+  public static empty(): ContractDeploymentData {
+    return new ContractDeploymentData(Point.ZERO, Fr.ZERO, Fr.ZERO, Fr.ZERO, EthAddress.ZERO);
+  }
+
+  isEmpty() {
+    return (
+      this.publicKey.isZero() &&
+      this.initializationHash.isZero() &&
+      this.contractClassId.isZero() &&
+      this.contractAddressSalt.isZero() &&
+      this.portalContractAddress.isZero()
+    );
+  }
+
+  /**
+   * Deserializes contract deployment data rom a buffer or reader.
+   * @param buffer - Buffer to read from.
+   * @returns The deserialized ContractDeploymentData.
+   */
+  static fromBuffer(buffer: Buffer | BufferReader): ContractDeploymentData {
+    const reader = BufferReader.asReader(buffer);
+    return new ContractDeploymentData(
+      reader.readObject(Point),
+      Fr.fromBuffer(reader),
+      Fr.fromBuffer(reader),
+      Fr.fromBuffer(reader),
+      new EthAddress(reader.readBytes(32)),
+    );
+  }
+
+  static fromFields(fields: Fr[] | FieldReader): ContractDeploymentData {
+    const reader = FieldReader.asReader(fields);
+
+    const publicKey = Point.fromFields(reader);
+    const initializationHash = reader.readField();
+    const contractClassId = reader.readField();
+    const contractAddressSalt = reader.readField();
+    const portalContractAddress = new EthAddress(reader.readField().toBuffer());
+
+    return new ContractDeploymentData(
+      publicKey,
+      initializationHash,
+      contractClassId,
+      contractAddressSalt,
+      portalContractAddress,
+    );
+  }
+}
diff --git a/yarn-project/circuits.js/src/structs/function_data.ts b/yarn-project/circuits.js/src/structs/function_data.ts
index 7bafa4c126a..d35eb8dfffa 100644
--- a/yarn-project/circuits.js/src/structs/function_data.ts
+++ b/yarn-project/circuits.js/src/structs/function_data.ts
@@ -1,7 +1,7 @@
 import { FunctionAbi, FunctionSelector, FunctionType } from '@aztec/foundation/abi';
-import { BufferReader, serializeToBuffer } from '@aztec/foundation/serialize';
+import { BufferReader, FieldReader, serializeToBuffer } from '@aztec/foundation/serialize';
 
-import { ContractFunctionDao } from '../index.js';
+import { ContractFunctionDao, Fr } from '../index.js';
 
 /**
  * Function description for circuit.
@@ -44,6 +44,10 @@ export class FunctionData {
     return serializeToBuffer(this.selector, this.isInternal, this.isPrivate, this.isConstructor);
   }
 
+  toFields(): Fr[] {
+    return [this.selector.toField(), new Fr(this.isInternal), new Fr(this.isPrivate), new Fr(this.isConstructor)];
+  }
+
   /**
    * Returns whether this instance is empty.
    * @returns True if the function selector is zero.
@@ -93,4 +97,15 @@ export class FunctionData {
       reader.readBoolean(),
     );
   }
+
+  static fromFields(fields: Fr[] | FieldReader): FunctionData {
+    const reader = FieldReader.asReader(fields);
+
+    const selector = FunctionSelector.fromFields(reader);
+    const isInternal = reader.readBoolean();
+    const isPrivate = reader.readBoolean();
+    const isConstructor = reader.readBoolean();
+
+    return new FunctionData(selector, isInternal, isPrivate, isConstructor);
+  }
 }
diff --git a/yarn-project/circuits.js/src/structs/global_variables.ts b/yarn-project/circuits.js/src/structs/global_variables.ts
index fd353693a10..04491e46aba 100644
--- a/yarn-project/circuits.js/src/structs/global_variables.ts
+++ b/yarn-project/circuits.js/src/structs/global_variables.ts
@@ -1,5 +1,5 @@
 import { Fr } from '@aztec/foundation/fields';
-import { BufferReader, serializeToBuffer } from '@aztec/foundation/serialize';
+import { BufferReader, FieldReader, serializeToBuffer } from '@aztec/foundation/serialize';
 import { FieldsOf } from '@aztec/foundation/types';
 
 /**
@@ -52,6 +52,12 @@ export class GlobalVariables {
     );
   }
 
+  static fromFields(fields: Fr[] | FieldReader): GlobalVariables {
+    const reader = FieldReader.asReader(fields);
+
+    return new GlobalVariables(reader.readField(), reader.readField(), reader.readField(), reader.readField());
+  }
+
   static getFields(fields: FieldsOf<GlobalVariables>) {
     // Note: The order here must match the order in the HeaderLib solidity library.
     return [fields.chainId, fields.version, fields.blockNumber, fields.timestamp] as const;
@@ -61,7 +67,7 @@ export class GlobalVariables {
     return serializeToBuffer(...GlobalVariables.getFields(this));
   }
 
-  toFieldArray() {
+  toFields() {
     return GlobalVariables.getFields(this);
   }
 
diff --git a/yarn-project/circuits.js/src/structs/header.test.ts b/yarn-project/circuits.js/src/structs/header.test.ts
index 72d49ae9bf2..9f25ffc0648 100644
--- a/yarn-project/circuits.js/src/structs/header.test.ts
+++ b/yarn-project/circuits.js/src/structs/header.test.ts
@@ -14,8 +14,8 @@ describe('Header', () => {
     const randomInt = Math.floor(Math.random() * 1000);
     const expected = makeHeader(randomInt, undefined);
 
-    const fieldArray = expected.toFieldArray();
-    const res = Header.fromFieldArray(fieldArray);
+    const fieldArray = expected.toFields();
+    const res = Header.fromFields(fieldArray);
     expect(res).toEqual(expected);
   });
 
diff --git a/yarn-project/circuits.js/src/structs/header.ts b/yarn-project/circuits.js/src/structs/header.ts
index 016f9e9f98e..5923e869541 100644
--- a/yarn-project/circuits.js/src/structs/header.ts
+++ b/yarn-project/circuits.js/src/structs/header.ts
@@ -1,10 +1,9 @@
 import { pedersenHash } from '@aztec/foundation/crypto';
 import { Fr } from '@aztec/foundation/fields';
-import { BufferReader, from2Fields, serializeToBuffer, to2Fields } from '@aztec/foundation/serialize';
+import { BufferReader, FieldReader, from2Fields, serializeToBuffer, to2Fields } from '@aztec/foundation/serialize';
 
 import { GeneratorIndex, HEADER_LENGTH } from '../constants.gen.js';
 import { GlobalVariables } from './global_variables.js';
-import { PartialStateReference } from './partial_state_reference.js';
 import { AppendOnlyTreeSnapshot } from './rollup/append_only_tree_snapshot.js';
 import { StateReference } from './state_reference.js';
 
@@ -32,13 +31,13 @@ export class Header {
     return serializeToBuffer(this.lastArchive, this.bodyHash, this.state, this.globalVariables);
   }
 
-  toFieldArray(): Fr[] {
+  toFields(): Fr[] {
     // Note: The order here must match the order in header.nr
     const serialized = [
-      ...this.lastArchive.toFieldArray(),
+      ...this.lastArchive.toFields(),
       ...to2Fields(this.bodyHash),
       ...this.state.toFieldArray(),
-      ...this.globalVariables.toFieldArray(),
+      ...this.globalVariables.toFields(),
     ];
     if (serialized.length !== HEADER_LENGTH) {
       throw new Error(`Expected header to have ${HEADER_LENGTH} fields, but it has ${serialized.length} fields`);
@@ -57,23 +56,13 @@ export class Header {
     );
   }
 
-  static fromFieldArray(fields: Fr[]): Header {
-    if (fields.length !== HEADER_LENGTH) {
-      throw new Error(`Expected header to have ${HEADER_LENGTH} fields, but it has ${fields.length} fields`);
-    }
-    // Note: The order here must match the order in header.nr
-    const lastArchive = new AppendOnlyTreeSnapshot(fields[0], Number(fields[1].toBigInt()));
-    const bodyHash = from2Fields(fields[2], fields[3]);
-    const state = new StateReference(
-      new AppendOnlyTreeSnapshot(fields[4], Number(fields[5].toBigInt())),
-      new PartialStateReference(
-        new AppendOnlyTreeSnapshot(fields[6], Number(fields[7].toBigInt())),
-        new AppendOnlyTreeSnapshot(fields[8], Number(fields[9].toBigInt())),
-        new AppendOnlyTreeSnapshot(fields[10], Number(fields[11].toBigInt())),
-        new AppendOnlyTreeSnapshot(fields[12], Number(fields[13].toBigInt())),
-      ),
-    );
-    const globalVariables = new GlobalVariables(fields[14], fields[15], fields[16], fields[17]);
+  static fromFields(fields: Fr[] | FieldReader): Header {
+    const reader = FieldReader.asReader(fields);
+
+    const lastArchive = new AppendOnlyTreeSnapshot(reader.readField(), Number(reader.readField().toBigInt()));
+    const bodyHash = from2Fields(reader.readField(), reader.readField());
+    const state = StateReference.fromFields(reader);
+    const globalVariables = GlobalVariables.fromFields(reader);
 
     return new Header(lastArchive, bodyHash, state, globalVariables);
   }
@@ -112,7 +101,7 @@ export class Header {
   hash(): Fr {
     return Fr.fromBuffer(
       pedersenHash(
-        this.toFieldArray().map(f => f.toBuffer()),
+        this.toFields().map(f => f.toBuffer()),
         GeneratorIndex.BLOCK_HASH,
       ),
     );
diff --git a/yarn-project/circuits.js/src/structs/index.ts b/yarn-project/circuits.js/src/structs/index.ts
index ca2cb39c1c6..2218c043152 100644
--- a/yarn-project/circuits.js/src/structs/index.ts
+++ b/yarn-project/circuits.js/src/structs/index.ts
@@ -4,6 +4,7 @@ export * from './call_context.js';
 export * from './call_request.js';
 export * from './call_stack_item.js';
 export * from './complete_address.js';
+export * from './contract_deployment_data.js';
 export * from './function_data.js';
 export * from './function_leaf_preimage.js';
 export * from './global_variables.js';
diff --git a/yarn-project/circuits.js/src/structs/partial_state_reference.ts b/yarn-project/circuits.js/src/structs/partial_state_reference.ts
index 7e375eeb12a..369b0732c41 100644
--- a/yarn-project/circuits.js/src/structs/partial_state_reference.ts
+++ b/yarn-project/circuits.js/src/structs/partial_state_reference.ts
@@ -1,4 +1,5 @@
-import { BufferReader, serializeToBuffer } from '@aztec/foundation/serialize';
+import { Fr } from '@aztec/foundation/fields';
+import { BufferReader, FieldReader, serializeToBuffer } from '@aztec/foundation/serialize';
 
 import { AppendOnlyTreeSnapshot } from './rollup/append_only_tree_snapshot.js';
 
@@ -27,6 +28,17 @@ export class PartialStateReference {
     );
   }
 
+  static fromFields(fields: Fr[] | FieldReader): PartialStateReference {
+    const reader = FieldReader.asReader(fields);
+
+    const noteHashTree = AppendOnlyTreeSnapshot.fromFields(reader);
+    const nullifierTree = AppendOnlyTreeSnapshot.fromFields(reader);
+    const contractTree = AppendOnlyTreeSnapshot.fromFields(reader);
+    const publicDataTree = AppendOnlyTreeSnapshot.fromFields(reader);
+
+    return new PartialStateReference(noteHashTree, nullifierTree, contractTree, publicDataTree);
+  }
+
   static empty(): PartialStateReference {
     return new PartialStateReference(
       AppendOnlyTreeSnapshot.zero(),
@@ -40,12 +52,12 @@ export class PartialStateReference {
     return serializeToBuffer(this.noteHashTree, this.nullifierTree, this.contractTree, this.publicDataTree);
   }
 
-  toFieldArray() {
+  toFields() {
     return [
-      ...this.noteHashTree.toFieldArray(),
-      ...this.nullifierTree.toFieldArray(),
-      ...this.contractTree.toFieldArray(),
-      ...this.publicDataTree.toFieldArray(),
+      ...this.noteHashTree.toFields(),
+      ...this.nullifierTree.toFields(),
+      ...this.contractTree.toFields(),
+      ...this.publicDataTree.toFields(),
     ];
   }
 
diff --git a/yarn-project/circuits.js/src/structs/private_circuit_public_inputs.test.ts b/yarn-project/circuits.js/src/structs/private_circuit_public_inputs.test.ts
index a5f54760c11..fd7cea4b38d 100644
--- a/yarn-project/circuits.js/src/structs/private_circuit_public_inputs.test.ts
+++ b/yarn-project/circuits.js/src/structs/private_circuit_public_inputs.test.ts
@@ -1,6 +1,21 @@
+import { makePrivateCircuitPublicInputs } from '../tests/factories.js';
 import { PrivateCircuitPublicInputs } from './private_circuit_public_inputs.js';
 
 describe('PrivateCircuitPublicInputs', () => {
+  it('serializes to buffer and back', () => {
+    const target = makePrivateCircuitPublicInputs(100);
+    const buffer = target.toBuffer();
+    const result = PrivateCircuitPublicInputs.fromBuffer(buffer);
+    expect(result).toEqual(target);
+  });
+
+  it('serializes to fields and back', () => {
+    const target = makePrivateCircuitPublicInputs(100);
+    const fields = target.toFields();
+    const result = PrivateCircuitPublicInputs.fromFields(fields);
+    expect(result).toEqual(target);
+  });
+
   it(`initializes an empty PrivateCircuitPublicInputs`, () => {
     const target = PrivateCircuitPublicInputs.empty();
     expect(target.isEmpty()).toBe(true);
diff --git a/yarn-project/circuits.js/src/structs/private_circuit_public_inputs.ts b/yarn-project/circuits.js/src/structs/private_circuit_public_inputs.ts
index 9ddd2fbcdde..c5f7332d6c6 100644
--- a/yarn-project/circuits.js/src/structs/private_circuit_public_inputs.ts
+++ b/yarn-project/circuits.js/src/structs/private_circuit_public_inputs.ts
@@ -1,7 +1,13 @@
 import { makeTuple } from '@aztec/foundation/array';
 import { isArrayEmpty } from '@aztec/foundation/collection';
 import { Fr } from '@aztec/foundation/fields';
-import { BufferReader, Tuple, serializeToBuffer } from '@aztec/foundation/serialize';
+import {
+  BufferReader,
+  FieldReader,
+  Tuple,
+  serializeToBuffer,
+  serializeToFieldArray,
+} from '@aztec/foundation/serialize';
 import { FieldsOf } from '@aztec/foundation/types';
 
 import {
@@ -16,9 +22,8 @@ import {
   RETURN_VALUES_LENGTH,
 } from '../constants.gen.js';
 import { CallContext } from './call_context.js';
-import { Header, SideEffect, SideEffectLinkedToNoteHash } from './index.js';
+import { ContractDeploymentData, Header, SideEffect, SideEffectLinkedToNoteHash } from './index.js';
 import { NullifierKeyValidationRequest } from './nullifier_key_validation_request.js';
-import { ContractDeploymentData } from './tx_context.js';
 
 /**
  * Public inputs to a private circuit.
@@ -154,6 +159,31 @@ export class PrivateCircuitPublicInputs {
     );
   }
 
+  static fromFields(fields: Fr[] | FieldReader): PrivateCircuitPublicInputs {
+    const reader = FieldReader.asReader(fields);
+    return new PrivateCircuitPublicInputs(
+      reader.readObject(CallContext),
+      reader.readField(),
+      reader.readFieldArray(RETURN_VALUES_LENGTH),
+      reader.readArray(MAX_READ_REQUESTS_PER_CALL, SideEffect),
+      reader.readArray(MAX_NULLIFIER_KEY_VALIDATION_REQUESTS_PER_CALL, NullifierKeyValidationRequest),
+      reader.readArray(MAX_NEW_COMMITMENTS_PER_CALL, SideEffect),
+      reader.readArray(MAX_NEW_NULLIFIERS_PER_CALL, SideEffectLinkedToNoteHash),
+      reader.readFieldArray(MAX_PRIVATE_CALL_STACK_LENGTH_PER_CALL),
+      reader.readFieldArray(MAX_PUBLIC_CALL_STACK_LENGTH_PER_CALL),
+      reader.readFieldArray(MAX_NEW_L2_TO_L1_MSGS_PER_CALL),
+      reader.readField(),
+      reader.readFieldArray(NUM_FIELDS_PER_SHA256),
+      reader.readFieldArray(NUM_FIELDS_PER_SHA256),
+      reader.readField(),
+      reader.readField(),
+      reader.readObject(Header),
+      reader.readObject(ContractDeploymentData),
+      reader.readField(),
+      reader.readField(),
+    );
+  }
+
   /**
    * Create an empty PrivateCircuitPublicInputs.
    * @returns An empty PrivateCircuitPublicInputs object.
@@ -237,6 +267,7 @@ export class PrivateCircuitPublicInputs {
       fields.version,
     ] as const;
   }
+
   /**
    * Serialize this as a buffer.
    * @returns The buffer.
@@ -244,4 +275,11 @@ export class PrivateCircuitPublicInputs {
   toBuffer(): Buffer {
     return serializeToBuffer(...PrivateCircuitPublicInputs.getFields(this));
   }
+
+  /**
+   * Serialize this as a field array.
+   */
+  toFields(): Fr[] {
+    return serializeToFieldArray(...PrivateCircuitPublicInputs.getFields(this));
+  }
 }
diff --git a/yarn-project/circuits.js/src/structs/rollup/append_only_tree_snapshot.ts b/yarn-project/circuits.js/src/structs/rollup/append_only_tree_snapshot.ts
index 09216a8a0a1..6f39790a162 100644
--- a/yarn-project/circuits.js/src/structs/rollup/append_only_tree_snapshot.ts
+++ b/yarn-project/circuits.js/src/structs/rollup/append_only_tree_snapshot.ts
@@ -1,5 +1,5 @@
 import { Fr } from '@aztec/foundation/fields';
-import { BufferReader, serializeToBuffer } from '@aztec/foundation/serialize';
+import { BufferReader, FieldReader, serializeToBuffer } from '@aztec/foundation/serialize';
 
 import { STRING_ENCODING, UInt32 } from '../shared.js';
 
@@ -30,7 +30,7 @@ export class AppendOnlyTreeSnapshot {
     return serializeToBuffer(this.root, this.nextAvailableLeafIndex);
   }
 
-  toFieldArray(): Fr[] {
+  toFields(): Fr[] {
     return [this.root, new Fr(this.nextAvailableLeafIndex)];
   }
 
@@ -47,6 +47,12 @@ export class AppendOnlyTreeSnapshot {
     return AppendOnlyTreeSnapshot.fromBuffer(Buffer.from(str, STRING_ENCODING));
   }
 
+  static fromFields(fields: Fr[] | FieldReader): AppendOnlyTreeSnapshot {
+    const reader = FieldReader.asReader(fields);
+
+    return new AppendOnlyTreeSnapshot(reader.readField(), Number(reader.readField().toBigInt()));
+  }
+
   static zero() {
     return new AppendOnlyTreeSnapshot(Fr.ZERO, 0);
   }
diff --git a/yarn-project/circuits.js/src/structs/state_reference.ts b/yarn-project/circuits.js/src/structs/state_reference.ts
index 284d988e07f..1e312739c15 100644
--- a/yarn-project/circuits.js/src/structs/state_reference.ts
+++ b/yarn-project/circuits.js/src/structs/state_reference.ts
@@ -1,5 +1,5 @@
 import { Fr } from '@aztec/foundation/fields';
-import { BufferReader, serializeToBuffer } from '@aztec/foundation/serialize';
+import { BufferReader, FieldReader, serializeToBuffer } from '@aztec/foundation/serialize';
 
 import { PartialStateReference } from './partial_state_reference.js';
 import { AppendOnlyTreeSnapshot } from './rollup/append_only_tree_snapshot.js';
@@ -21,7 +21,7 @@ export class StateReference {
   }
 
   toFieldArray(): Fr[] {
-    return [...this.l1ToL2MessageTree.toFieldArray(), ...this.partial.toFieldArray()];
+    return [...this.l1ToL2MessageTree.toFields(), ...this.partial.toFields()];
   }
 
   static fromBuffer(buffer: Buffer | BufferReader): StateReference {
@@ -29,6 +29,15 @@ export class StateReference {
     return new StateReference(reader.readObject(AppendOnlyTreeSnapshot), reader.readObject(PartialStateReference));
   }
 
+  static fromFields(fields: Fr[] | FieldReader): StateReference {
+    const reader = FieldReader.asReader(fields);
+
+    const l1ToL2MessageTree = AppendOnlyTreeSnapshot.fromFields(reader);
+    const partial = PartialStateReference.fromFields(reader);
+
+    return new StateReference(l1ToL2MessageTree, partial);
+  }
+
   static empty(): StateReference {
     return new StateReference(AppendOnlyTreeSnapshot.zero(), PartialStateReference.empty());
   }
diff --git a/yarn-project/circuits.js/src/structs/tx_context.ts b/yarn-project/circuits.js/src/structs/tx_context.ts
index f84a47b5b8c..07becc7f95e 100644
--- a/yarn-project/circuits.js/src/structs/tx_context.ts
+++ b/yarn-project/circuits.js/src/structs/tx_context.ts
@@ -1,83 +1,10 @@
 import { BufferReader, serializeToBuffer } from '@aztec/foundation/serialize';
 import { FieldsOf } from '@aztec/foundation/types';
 
-import { PublicKey } from '../index.js';
-import { AztecAddress, EthAddress, Fr, Point } from './index.js';
-
-/**
- * Contract deployment data in a TxContext
- * Not to be confused with NewContractData.
- */
-export class ContractDeploymentData {
-  /** Ethereum address of the portal contract on L1. */
-  public portalContractAddress: EthAddress;
-
-  constructor(
-    /** Public key of the contract. */
-    public publicKey: PublicKey,
-    /** Hash of the initialization payload. */
-    public initializationHash: Fr,
-    /** Contract class identifier. */
-    public contractClassId: Fr,
-    /** Contract address salt (used when deriving a contract address). */
-    public contractAddressSalt: Fr,
-    /**
-     * Ethereum address of the portal contract on L1.
-     * TODO(AD): union type kludge due to cbind compiler having special needs
-     */
-    portalContractAddress: EthAddress | AztecAddress,
-  ) {
-    this.portalContractAddress = EthAddress.fromField(portalContractAddress.toField());
-  }
-
-  toBuffer() {
-    return serializeToBuffer(
-      this.publicKey,
-      this.initializationHash,
-      this.contractClassId,
-      this.contractAddressSalt,
-      this.portalContractAddress,
-    );
-  }
-
-  /**
-   * Returns an empty ContractDeploymentData.
-   * @returns The empty ContractDeploymentData.
-   */
-  public static empty(): ContractDeploymentData {
-    return new ContractDeploymentData(Point.ZERO, Fr.ZERO, Fr.ZERO, Fr.ZERO, EthAddress.ZERO);
-  }
-
-  isEmpty() {
-    return (
-      this.publicKey.isZero() &&
-      this.initializationHash.isZero() &&
-      this.contractClassId.isZero() &&
-      this.contractAddressSalt.isZero() &&
-      this.portalContractAddress.isZero()
-    );
-  }
-
-  /**
-   * Deserializes contract deployment data rom a buffer or reader.
-   * @param buffer - Buffer to read from.
-   * @returns The deserialized ContractDeploymentData.
-   */
-  static fromBuffer(buffer: Buffer | BufferReader): ContractDeploymentData {
-    const reader = BufferReader.asReader(buffer);
-    return new ContractDeploymentData(
-      reader.readObject(Point),
-      Fr.fromBuffer(reader),
-      Fr.fromBuffer(reader),
-      Fr.fromBuffer(reader),
-      new EthAddress(reader.readBytes(32)),
-    );
-  }
-}
+import { ContractDeploymentData, Fr } from './index.js';
 
 /**
  * Transaction context.
- * @see cpp/src/aztec3/circuits/abis/tx_context.hpp.
  */
 export class TxContext {
   constructor(
diff --git a/yarn-project/foundation/src/serialize/serialize.ts b/yarn-project/foundation/src/serialize/serialize.ts
index 5ab8a8ac5c4..d8eef08529b 100644
--- a/yarn-project/foundation/src/serialize/serialize.ts
+++ b/yarn-project/foundation/src/serialize/serialize.ts
@@ -1,5 +1,6 @@
 import { toBigIntBE, toBufferBE } from '@aztec/foundation/bigint-buffer';
 
+import { Fr } from '../fields/fields.js';
 import { numToUInt32BE } from './free_funcs.js';
 
 /**
@@ -118,6 +119,22 @@ export type Bufferable =
     }
   | Bufferable[];
 
+/** A type that can be converted to a Field or a Field array. */
+export type Fieldeable =
+  | Fr
+  | boolean
+  | number
+  | bigint
+  | {
+      /** Serialize to a field. */
+      toField: () => Fr;
+    }
+  | {
+      /** Serialize to an array of fields. */
+      toFields: () => Fr[];
+    }
+  | Fieldeable[];
+
 /**
  * Checks whether an object implements the toBuffer32 method.
  * @param obj - The object to check.
@@ -168,6 +185,29 @@ export function serializeToBufferArray(...objs: Bufferable[]): Buffer[] {
   return ret;
 }
 
+/**
+ * Serializes a list of objects contiguously.
+ * @param objs - Objects to serialize.
+ * @returns An array of fields with the concatenation of all fields.
+ */
+export function serializeToFieldArray(...objs: Fieldeable[]): Fr[] {
+  let ret: Fr[] = [];
+  for (const obj of objs) {
+    if (Array.isArray(obj)) {
+      ret = [...ret, ...serializeToFieldArray(...obj)];
+    } else if (obj instanceof Fr) {
+      ret.push(obj);
+    } else if (typeof obj === 'boolean' || typeof obj === 'number' || typeof obj === 'bigint') {
+      ret.push(new Fr(obj));
+    } else if ('toFields' in obj) {
+      ret = [...ret, ...obj.toFields()];
+    } else {
+      ret.push(obj.toField());
+    }
+  }
+  return ret;
+}
+
 /**
  * Serializes a list of objects contiguously.
  * @param objs - Objects to serialize.
diff --git a/yarn-project/noir-protocol-circuits/src/type_conversion.test.ts b/yarn-project/noir-protocol-circuits/src/type_conversion.test.ts
index 96295999765..562d9aa09e0 100644
--- a/yarn-project/noir-protocol-circuits/src/type_conversion.test.ts
+++ b/yarn-project/noir-protocol-circuits/src/type_conversion.test.ts
@@ -59,7 +59,7 @@ describe('Noir<>Circuits.js type conversion test suite', () => {
       new Fr(29n),
       new Fr(30n),
       new Fr(31n),
-      AztecAddress.random(),
+      EthAddress.random(),
     );
 
     it('should map contract deployment data', () => {
diff --git a/yarn-project/pxe/src/simulator_oracle/index.ts b/yarn-project/pxe/src/simulator_oracle/index.ts
index a7b2a4dcd81..6077752fdcb 100644
--- a/yarn-project/pxe/src/simulator_oracle/index.ts
+++ b/yarn-project/pxe/src/simulator_oracle/index.ts
@@ -123,11 +123,7 @@ export class SimulatorOracle implements DBOracle {
     const message = messageAndIndex.message.toFieldArray();
     const index = messageAndIndex.index;
     const siblingPath = await this.stateInfoProvider.getL1ToL2MessageSiblingPath('latest', index);
-    return {
-      message,
-      siblingPath: siblingPath.toFieldArray(),
-      index,
-    };
+    return new MessageLoadOracleInputs(message, index, siblingPath.toFieldArray());
   }
 
   /**
diff --git a/yarn-project/sequencer-client/src/simulator/public_executor.ts b/yarn-project/sequencer-client/src/simulator/public_executor.ts
index 9015fb06bc4..de082839ab0 100644
--- a/yarn-project/sequencer-client/src/simulator/public_executor.ts
+++ b/yarn-project/sequencer-client/src/simulator/public_executor.ts
@@ -150,11 +150,7 @@ export class WorldStateDB implements CommitmentsDB {
     const index = (await this.db.findLeafIndex(MerkleTreeId.L1_TO_L2_MESSAGE_TREE, messageKey.toBuffer()))!;
     const siblingPath = await this.db.getSiblingPath(MerkleTreeId.L1_TO_L2_MESSAGE_TREE, index);
 
-    return {
-      message: message.toFieldArray(),
-      siblingPath: siblingPath.toFieldArray(),
-      index,
-    };
+    return new MessageLoadOracleInputs(message.toFieldArray(), index, siblingPath.toFieldArray());
   }
 
   public async getCommitmentIndex(commitment: Fr): Promise<bigint | undefined> {