Aztec Pxe

PXE Private Execution Operations

Overview

Use this skill for direct @aztec/pxe work.

Primary scope:

• private execution lifecycle (simulateTx, profileTx, proveTx, executeUtility)
• note discovery/synchronization behavior and scope control
• sender/recipient tagging workflows
• private event retrieval and filter handling
• oracle compatibility checks and PXE debug helpers

Out of scope:

• Noir/Aztec.nr contract authoring (use aztec-contracts)
• generic Aztec.js app flows that do not need direct PXE control (use aztec-js)
• deployment-focused procedures (use aztec-deployment)

Required Repository State

Use the upstream repository and pin:

• Repo: https://github.com/AztecProtocol/aztec-packages
• Tag: v4.2.0
• Commit: f8c89cf4345df6c4ca9e66ea9b738e96070abc5a
• Source root: yarn-project/pxe

Checkout example:

git clone https://github.com/AztecProtocol/aztec-packages.git
cd aztec-packages
git checkout v4.2.0
git status

Expected status includes HEAD detached at v4.2.0.

Operating Rules

• Treat PXE as a serialized execution environment: high-level jobs are queued and run one-at-a-time.
• Always pass an explicit scopes: AztecAddress[] list; the 'ALL_SCOPES' sentinel was removed. To emulate the old "see everything" behavior, pass the enumerated list of registered addresses: scopes = (await pxe.getRegisteredAccounts()).map(a => a.address).
• Capsule access is enforced at the PXE level in v4.2.0: a contract touching capsules scoped to an address not in the tx's scopes list fails at runtime with Scope 0x… is not in the allowed scopes list: [...]. AztecAddress::zero() is always permitted (global scope).
• Register recipient accounts with registerAccount(...) before expecting note or private event visibility.
• Register counterpart senders with registerSender(...) when syncing tagged logs across peers.
• Use simulateTx before proveTx; only prove after simulation and sync checks pass.
• For private events, filter.scopes must be non-empty and block range follows [fromBlock, toBlock).
• Use debug.getNotes(...) only for diagnostics; prefer contract utility functions for production reads.
• If oracle interface changes, run oracle version checks before trusting cross-version simulations.

Quick Start

# install dependencies in your app
scripts/install_pxe_deps.sh npm

# check node reachability + optional pxe source path validation
scripts/preflight_pxe.sh http://localhost:8080 /path/to/aztec-packages/yarn-project/pxe

import { createAztecNodeClient, waitForNode } from '@aztec/aztec.js/node';
import { createPXE, getPXEConfig } from '@aztec/pxe/server';

const node = createAztecNodeClient('http://localhost:8080');
await waitForNode(node);

const pxe = await createPXE(node, getPXEConfig(), {
  loggerActorLabel: 'app-pxe',
});

Core Workflows

1. Boot PXE and Anchor State

• Build node client and wait for JSON-RPC readiness.
• Create PXE via createPXE(...) from @aztec/pxe/server or @aztec/pxe/client/lazy.
• Use getSyncedBlockHeader() to confirm the current anchor block before execution.

2. Register Accounts, Senders, and Contract Data

• Register account recipients via registerAccount(secretKey, partialAddress).
• Register known counterpart senders via registerSender(senderAddress).
• Register artifacts/instances via registerContractClass(...) and registerContract(...).
• Verify registration with getRegisteredAccounts(), getSenders(), getContractInstance().

3. Run Private Execution Lifecycle

• simulateTx(txRequest, opts) for private (and optional public) simulation.
  • opts.overrides?: SimulationOverrides injects simulation-time contract instances/artifacts (useful for testing).
• profileTx(txRequest, { profileMode, scopes }) for execution/gate diagnostics.
  • profileMode values: 'full' | 'execution-steps' | 'gates'.
• proveTx(txRequest, scopes) only after simulation correctness is confirmed.
  • Returns TxProvingResult; publicInputs is non-optional on the result.
• executeUtility(functionCall, { authwits, scopes }) for utility paths and sync-state calls.

4. Note Discovery and Synchronization

• PXE sync occurs before simulation/event operations; keep one execution flow per state transition.
• Contract sync is scope-aware; [] scopes deny access and skip sync.
• Use debug.sync() to force an explicit sync checkpoint when diagnosing stale state.
• Use debug.getNotes({ contractAddress, owner?, storageSlot?, status?, siloedNullifier?, scopes }) for note-level diagnostics.

5. Tagging (Sender / Recipient)

• Sender-side index progression is maintained per directional secret (sender, recipient, contract).
• Recipient-side log loading scans bounded windows of tagging indexes and updates aged/finalized indices.
• Registering sender addresses improves recipient decryption coverage for incoming private logs.
• If tags are reused unexpectedly, inspect pending/finalized index movement and tx inclusion timing.

6. Private Events

• Retrieve private events via getPrivateEvents(eventSelector, filter).
• Required filter fields:
• contractAddress
• scopes (non-empty)
• Optional filters: txHash, fromBlock, toBlock (toBlock exclusive).
• If events are missing, ensure account registration, scope inclusion, and anchor sync point.

7. Oracle and Debug Workflows

• Verify oracle compatibility with scripts/check_oracle_version.sh against your pinned aztec-packages checkout.
• Use utilityLog outputs and simulation traces (profileTx) to localize oracle call failures.
• Treat PXEDebugUtils APIs as unstable and diagnostics-only.

8. Shutdown and Resource Hygiene

• Call pxe.stop() on teardown to end queued jobs cleanly.
• Preserve persistent store state across sessions when reproducing note/tagging issues.

Tooling / Commands

# preflight node/package manager/source checks
scripts/preflight_pxe.sh [node-url] [pxe-dir]

# install core PXE dependencies
scripts/install_pxe_deps.sh <npm|yarn|pnpm> [version]

# wait for node JSON-RPC readiness
scripts/wait_for_aztec_node.sh <node-url> [timeout-seconds] [interval-seconds]

# run a TypeScript example via tsx
scripts/run_pxe_example.sh <entry-file.ts> [-- <extra-args...>]

# summarize pxe package exports + method surfaces
scripts/summarize_pxe_surface.sh <aztec-packages-dir>

# run @aztec/pxe package tests
scripts/run_pxe_tests.sh <aztec-packages-dir> [test-path-pattern]

# run oracle interface compatibility check
scripts/check_oracle_version.sh <aztec-packages-dir>

Edge Cases and Failure Handling

• At least one scope is required to get private events: provide non-empty filter.scopes.
• Missing private notes/events despite successful tx: verify recipient account registration and scope membership.
• Incompatible oracle version error: run oracle version check and align Aztec.nr/PXE versions.
• Simulations appear stale after chain changes: force debug.sync() and re-run with fresh anchor block.
• Interleaved requests behave unpredictably: avoid app-side concurrent PXE operation bursts; serialize user flows.
• Tagging sync does not advance: verify sender registration and inspect finalized/aged tagging index windows.

Next Steps / Related Files

• Use reference.md for source map and API/file coverage.
• Use patterns.md for reusable workflow snippets.
• Use scripts/ for repeatable diagnostics and verification.