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Midnight.js v4.0.2 release notes

  • Version: v4.0.2
  • Date: March 24, 2026
  • Node.js requirement: >=22

High-level summary​

This release stabilizes the v4.0.x line by preserving core v4 capabilities while reverting a transaction construction path that caused failures in shielded coin flows.

It also improves proving provider configuration, contract error typing, security hardening, and operational reliability across transaction handling.

Audience​

This release note is most relevant for developers who:

  • Upgraded to v4.0.1 and adopted the addCalls-based call transaction flow.
  • Build contracts that use shielded coin operations.
  • Run HTTP proof providers requiring authentication headers.
  • Maintain custom error handling for Effect-based contract errors.

Summary of updates​

  • Added custom headers support in httpClientProvingProvider
  • Added isEffectContractError type guard for safe error narrowing
  • Reverted createUnprovenLedgerCallTx internals to restore shielded-call reliability
  • Fixed Merkle-tree rehash handling before contract-owned spend validation
  • Improved compact error propagation for deploy flows
  • Fixed fallible transaction error construction and reporting

New features​

This release adds focused developer ergonomics for proving-provider configuration and safer error handling.

Headers support in httpClientProvingProvider​

The HTTP client proving provider now supports custom headers for all requests to the proof server. This enables authentication tokens, API keys, or other custom headers to be forwarded with proof generation and verification requests.

Usage:

import { httpClientProvingProvider } from '@midnight-ntwrk/http-client-proof-provider';

const provider = httpClientProvingProvider(zkConfigProvider, proofServerUrl, {
  timeout: 60_000,
  headers: {
    'Authorization': 'Bearer <token>',
    'X-Custom-Header': 'value'
  }
});

API interface:

export interface ProvingProviderConfig {
  readonly timeout?: number;
  readonly headers?: Record<string, string>;  // NEW
}

Headers are merged with { 'Content-Type': 'application/octet-stream' } as the base, so custom headers take precedence over defaults.

isEffectContractError type guard​

A new type guard for safely narrowing Effect-ts contract errors without as any casts. Used internally in unproven-call-tx.ts and unproven-deploy-tx.ts, and exported from @midnight-ntwrk/midnight-js-contracts for use in custom error handling.

Usage:

import { isEffectContractError } from '@midnight-ntwrk/midnight-js-contracts';

try {
  await executeCircuit();
} catch (error) {
  if (isEffectContractError(error) && error._tag === 'ContractRuntimeError') {
    // Safely access error.cause without any casts
    console.error(error.cause.message);
  }
}

Breaking changes​

This release introduces no new breaking APIs. However, it reverts v4.0.1 breaking change #4 (addCalls transaction-construction migration), so teams that already adapted to v4.0.1 must revert those adaptations.

Revert of v4.0.1 addCalls migration​

What changed: createUnprovenLedgerCallTx behavior was restored from the v4.0.1 addCalls path to the v3.2.0-compatible ContractCallPrototype/PartitionedTranscript approach.

What breaks: Implementations migrated to the v4.0.1 publicTranscript + ledgerParameters call signature can fail or become incompatible in v4.0.2.

Required actions:

  • Replace publicTranscript with partitionedTranscript: PartitionedTranscript in createUnprovenLedgerCallTx call sites.
  • Remove ledgerParameters from createUnprovenLedgerCallTx call arguments (while keeping ledgerParameters in CallOptionsProviderDataDependencies, which remains required).
  • Restore extractUserAddressedOutputs usage where it was removed for v4.0.1 compatibility workarounds.

Restored API shape:

// v4.0.2 restored shape
createUnprovenLedgerCallTx(
  circuitId: AnyProvableCircuitId,
  contractAddress: ContractAddress,
  initialContractState: ContractState,
  zswapChainState: ZswapChainState,
  partitionedTranscript: PartitionedTranscript,
  privateTranscriptOutputs: AlignedValue[],
  input: AlignedValue,
  output: AlignedValue,
  nextZswapLocalState: ZswapLocalState,
  encryptionPublicKey: EncPublicKey
): UnprovenTransaction

Common migration issues​

The following runtime errors are commonly resolved by upgrading to v4.0.2 and reverting v4.0.1 addCalls-specific adaptations.

Error: "expected a cell, received null" on shielded operations​

Cause: v4.0.1 addCalls stack initialization mismatch for contracts using receiveShielded, sendShielded, or writeCoin.

Resolution: Use v4.0.2 transaction construction path (restored prototype approach).

Error: "attempted to spend from a Merkle tree that was not rehashed"​

Cause: The chain state's Merkle tree was not rehashed before constructing inclusion proofs.

Resolution: v4.0.2 updates zswapStateToOffer to call postBlockUpdate() before input construction.

Bug fixes​

This release resolves correctness and reliability issues in transaction construction, fallible transaction reporting, and deploy-time error propagation.

Revert createUnprovenLedgerCallTx to ContractCallPrototype approach​

The PreTranscript + Transaction.addCalls() approach introduced in v4.0.1 fails for contracts using shielded coin operations (receiveShielded, sendShielded, writeCoin). The addCalls() stack machine does not initialize its stack identically to compact-runtime's queryLedgerState during circuit execution, causing "expected a cell, received null" errors when shielded operations produce dup ops expecting items on the initial stack.

Reverted createUnprovenLedgerCallTx to use ContractCallPrototype + Intent.addCall() with PartitionedTranscript, which correctly handles shielded coin operations.

Affected contracts: Any contract using receiveShielded, sendShielded, or writeCoin (for example, Seabattle join_p1/join_p2, Lunarswap addLiquidity).

Rehash ZswapChainState before spending from Merkle tree​

ZswapInput.newContractOwned in ledger-v8 requires the chain state's Merkle tree to be rehashed before validating coin inclusion proofs. The zswapStateToOffer function now calls postBlockUpdate() on the chain state before constructing inputs. Without this, contracts that spend coins deposited in a prior transaction (for example, Seabattle join_p2 calling mergeCoinImmediate on a coin from join_p1) fail with "attempted to spend from a Merkle tree that was not rehashed".

Fix CompactError propagation in createUnprovenDeployTxFromVerifierKeys​

The error handler in createUnprovenDeployTxFromVerifierKeys only checked for ContractRuntimeError when unwrapping errors from the contract runtime. The compact-js dependency now wraps initialState errors as ContractConfigurationError. Updated the handler to recognize both ContractRuntimeError and ContractConfigurationError, so CompactError messages propagate correctly to callers.

Fix fallible offer error reporting​

Two bugs in fallible transaction error reporting:

  • Map serialization in TxFailedError: segmentStatusMap was silently lost during JSON.stringify because Map is not natively serializable. The replacer now converts Map instances to plain objects via Object.fromEntries.
  • Incorrect scopeName in scoped transaction errors: Error messages referenced the options parameter (only set for nested transactions) instead of the resolved txOptions. Root transactions always displayed <unnamed> even when a scopeName was provided.

Fix fallible error handling​

Fixed error construction in fallible transaction handling where the error object was incorrectly built.

Replace error as any casts with type guard​

Introduced isEffectContractError type guard in errors.ts to safely narrow Effect-ts errors instead of using fragile (error as any) introspection. Removed all as-any casts and eslint-disable comments from catch blocks in unproven-call-tx.ts and unproven-deploy-tx.ts.

Known issues​

No critical known issues were identified at release time.