// The broken path (SDK default — hits the null offset bug)
await providers.publicDataProvider.queryContractState(contractAddress);
// ❌ Fails on preview/preprod with GraphQL error

// The working path — explicit query with no offset field at all
async function queryLatestContractState(
  indexerUrl: string,
  contractAddress: string,
): Promise<string | null> {
  const res = await fetch(indexerUrl, {
    method: 'POST',
    headers: { 'content-type': 'application/json' },
    body: JSON.stringify({
      query: `
        query LATEST_STATE($address: HexEncoded!) {
          contractAction(address: $address) {
            state
          }
        }
      `,
      variables: { address: contractAddress },
    }),
  });
  const payload = await res.json();
  if (payload.errors?.length) throw new Error(payload.errors.map((e: any) => e.message).join('; '));
  return payload.data?.contractAction?.state ?? null;
}

import { ContractState } from '@midnight-ntwrk/compact-runtime';
import { Counter } from './managed/counter'; // generated by compact compiler

// Helper: hex string → Uint8Array
function fromHex(hex: string): Uint8Array {
  const normalized = hex.startsWith('0x') ? hex.slice(2) : hex;
  const bytes = new Uint8Array(normalized.length / 2);
  for (let i = 0; i < normalized.length; i += 2) {
    bytes[i / 2] = parseInt(normalized.slice(i, i + 2), 16);
  }
  return bytes;
}

async function getContractLedgerState(
  indexerUrl: string,
  contractAddress: string,
) {
  const res = await fetch(indexerUrl, {
    method: 'POST',
    headers: { 'content-type': 'application/json' },
    body: JSON.stringify({
      query: `
        query($address: HexEncoded!) {
          contractAction(address: $address) {
            state
            zswapState
            transaction {
              block { ledgerParameters }
            }
          }
        }
      `,
      variables: { address: contractAddress },
    }),
  });

  const payload = await res.json();
  if (payload.errors?.length) throw new Error(payload.errors[0].message);

  const action = payload.data?.contractAction;
  if (!action) return null;

  // Deserialize raw hex → ContractState → typed ledger state
  const contractState = ContractState.deserialize(fromHex(action.state));
  const ledgerState = Counter.ledger(contractState.data);

  return ledgerState; // fully typed: ledgerState.round, ledgerState.message, etc.
}

import { LedgerParameters, ZswapChainState } from '@midnight-ntwrk/ledger-v8';

const action = payload.data?.contractAction;
if (action?.zswapState) {
  const zswapState = ZswapChainState.deserialize(fromHex(action.zswapState));
  const contractState = ContractState.deserialize(fromHex(action.state));
  const ledgerParams = action.transaction?.block?.ledgerParameters
    ? LedgerParameters.deserialize(fromHex(action.transaction.block.ledgerParameters))
    : LedgerParameters.initialParameters();

  return [zswapState, contractState, ledgerParams];
}

query {
  block {
    hash
    height
    timestamp
    protocolVersion
    ledgerParameters
    transactions {
      id
      hash
    }
  }
}

query {
  block(offset: { height: 42 }) {
    hash height timestamp
  }
}

query {
  block(offset: { hash: "3031323..." }) {
    hash height timestamp
  }
}

query($address: HexEncoded!) {
  contractAction(address: $address) {
    __typename
    address
    state
    zswapState
    transaction {
      hash
      block { height ledgerParameters }
      fees { paidFees estimatedFees }
    }
    unshieldedBalances {
      tokenType
      amount
    }
    ... on ContractCall {
      entryPoint
    }
  }
}

query($address: HexEncoded!) {
  contractAction(
    address: $address,
    offset: { blockOffset: { height: 100 } }
  ) {
    state
    zswapState
  }
}

query($address: HexEncoded!, $txHash: HexEncoded!) {
  contractAction(
    address: $address,
    offset: { transactionOffset: { hash: $txHash } }
  ) {
    state
  }
}

query($hash: HexEncoded!) {
  transactions(offset: { hash: $hash }) {
    id hash
    block { height hash }
    transactionResult {
      status
      segments { id success }
    }
    fees { paidFees estimatedFees }
    contractActions {
      __typename
      address
      state
      ... on ContractDeploy { address }
      ... on ContractCall { entryPoint }
    }
    unshieldedCreatedOutputs {
      owner value tokenType intentHash outputIndex
    }
    unshieldedSpentOutputs {
      owner value tokenType intentHash outputIndex
    }
  }
}

query($address: HexEncoded!) {
  contractAction(address: $address) {
    unshieldedBalances {
      tokenType   # hex-encoded token type identifier
      amount      # string (supports u128)
    }
  }
}

query {
  dustGenerationStatus(
    cardanoRewardAddresses: ["stake_test1uq..."]
  ) {
    cardanoRewardAddress
    dustAddress
    registered
    nightBalance
    generationRate
    currentCapacity
    maxCapacity
  }
}

import { ContractState } from '@midnight-ntwrk/compact-runtime';
import { LedgerParameters, ZswapChainState } from '@midnight-ntwrk/ledger-v8';
import { indexerPublicDataProvider } from '@midnight-ntwrk/midnight-js-indexer-public-data-provider';
import type { PublicDataProvider } from '@midnight-ntwrk/midnight-js-types';

function fromHex(hex: string): Uint8Array {
  const normalized = hex.startsWith('0x') ? hex.slice(2) : hex;
  const bytes = new Uint8Array(normalized.length / 2);
  for (let i = 0; i < normalized.length; i += 2) {
    bytes[i / 2] = parseInt(normalized.slice(i, i + 2), 16);
  }
  return bytes;
}

async function gqlQuery(url: string, query: string, variables: Record<string, unknown>) {
  const res = await fetch(url, {
    method: 'POST',
    headers: { 'content-type': 'application/json' },
    body: JSON.stringify({ query, variables }),
  });
  if (!res.ok) throw new Error(`Indexer HTTP ${res.status}`);
  const payload = await res.json();
  if (payload.errors?.length) throw new Error(payload.errors.map((e: any) => e.message).join('; '));
  return payload.data;
}

export function createPatchedPublicDataProvider(
  queryUrl: string,
  subscriptionUrl: string,
): PublicDataProvider {
  const base = indexerPublicDataProvider(queryUrl, subscriptionUrl);

  return {
    ...base,

    async queryContractState(contractAddress: string, config?: any) {
      // If config is provided, the SDK offset path works — pass through
      if (config) return base.queryContractState(contractAddress, config);

      // Without config → null offset bug → use manual query
      const data = await gqlQuery(queryUrl, `
        query LATEST_STATE($address: HexEncoded!) {
          contractAction(address: $address) { state }
        }
      `, { address: contractAddress });

      return data?.contractAction
        ? ContractState.deserialize(fromHex(data.contractAction.state))
        : null;
    },

    async queryZSwapAndContractState(contractAddress: string, config?: any) {
      if (config) return base.queryZSwapAndContractState(contractAddress, config);

      const data = await gqlQuery(queryUrl, `
        query LATEST_BOTH($address: HexEncoded!) {
          contractAction(address: $address) {
            state
            zswapState
            transaction { block { ledgerParameters } }
          }
        }
      `, { address: contractAddress });

      const action = data?.contractAction;
      if (!action?.zswapState) return null;

      return [
        ZswapChainState.deserialize(fromHex(action.zswapState)),
        ContractState.deserialize(fromHex(action.state)),
        action.transaction?.block?.ledgerParameters
          ? LedgerParameters.deserialize(fromHex(action.transaction.block.ledgerParameters))
          : LedgerParameters.initialParameters(),
      ] as [ZswapChainState, ContractState, LedgerParameters];
    },

    async queryUnshieldedBalances(contractAddress: string, config?: any) {
      if (config) return base.queryUnshieldedBalances(contractAddress, config);

      const data = await gqlQuery(queryUrl, `
        query LATEST_BALANCES($address: HexEncoded!) {
          contractAction(address: $address) {
            ... on ContractDeploy { unshieldedBalances { tokenType amount } }
            ... on ContractCall   { unshieldedBalances { tokenType amount } }
            ... on ContractUpdate { unshieldedBalances { tokenType amount } }
          }
        }
      `, { address: contractAddress });

      const action = data?.contractAction;
      if (!action) return null;
      const raw: Array<{ tokenType: string; amount: string }> =
        action.unshieldedBalances ?? [];
      return raw.map(e => ({ tokenType: e.tokenType, balance: BigInt(e.amount) }));
    },
  };
}

npm install graphql-ws ws

import { createClient } from 'graphql-ws';
import { WebSocket } from 'ws'; // Node.js only

const client = createClient({
  url: 'wss://indexer.preprod.midnight.network/api/v4/graphql/ws',
  webSocketImpl: typeof window === 'undefined' ? WebSocket : undefined,
});

const unsubscribe = client.subscribe(
  {
    query: `
      subscription WatchContract($address: HexEncoded!) {
        contractActions(address: $address) {
          __typename
          address
          state
          zswapState
          transaction {
            hash
            block { height timestamp }
            fees { paidFees }
          }
          ... on ContractCall {
            entryPoint
          }
        }
      }
    `,
    variables: { address: contractAddress },
  },
  {
    next(data) {
      const action = data.data?.contractActions;
      if (!action) return;

      // Deserialize raw state to typed ledger
      const contractState = ContractState.deserialize(fromHex(action.state));
      const ledgerState = YourContract.ledger(contractState.data);

      console.log('New state:', ledgerState);
      console.log('Entry point:', action.entryPoint); // which circuit was called
    },
    error(err) { console.error('Subscription error:', err); },
    complete() { console.log('Subscription closed'); },
  },
);

// Cleanup
unsubscribe();

variables: { address: contractAddress },
// Pass offset in the query to replay from block 100:
query: `subscription($address: HexEncoded!) {
  contractActions(address: $address, offset: { height: 100 }) { ... }
}`

client.subscribe(
  {
    query: `
      subscription {
        blocks {
          hash height timestamp
          transactions { id hash }
        }
      }
    `,
  },
  {
    next(data) { console.log('New block:', data.data?.blocks?.height); },
    error(err) { console.error(err); },
    complete() {},
  },
);

client.subscribe(
  {
    query: `
      subscription WatchAddress($address: UnshieldedAddress!) {
        unshieldedTransactions(address: $address) {
          __typename
          ... on UnshieldedTransaction {
            transaction { hash block { height } }
            createdUtxos { owner value tokenType intentHash outputIndex }
            spentUtxos  { owner value tokenType intentHash outputIndex }
          }
          ... on UnshieldedTransactionsProgress {
            highestTransactionId
          }
        }
      }
    `,
    variables: { address: 'mn_addr_preprod1...' },
  },
  {
    next(data) {
      const event = data.data?.unshieldedTransactions;
      if (event?.__typename === 'UnshieldedTransaction') {
        console.log('Created UTXOs:', event.createdUtxos);
        console.log('Spent UTXOs:', event.spentUtxos);
      }
    },
    error(err) { console.error(err); },
    complete() {},
  },
);

variables: { address: 'mn_addr_preprod1...', transactionId: 12345 },

// Step 1: get a session ID
const sessionRes = await fetch(indexerHttpUrl, {
  method: 'POST',
  headers: { 'content-type': 'application/json' },
  body: JSON.stringify({
    query: `mutation { connect(viewingKey: "mn_shield-esk1...") }`,
  }),
});
const { data } = await sessionRes.json();
const sessionId = data.connect;

// Step 2: subscribe
client.subscribe(
  {
    query: `
      subscription($sessionId: HexEncoded!, $index: Int) {
        shieldedTransactions(sessionId: $sessionId, index: $index) {
          __typename
          ... on RelevantTransaction {
            transaction { id hash }
            collapsedMerkleTree { startIndex endIndex update protocolVersion }
          }
          ... on ShieldedTransactionsProgress {
            highestEndIndex
            highestCheckedEndIndex
            highestRelevantEndIndex
          }
        }
      }
    `,
    variables: { sessionId, index: 0 },
  },
  {
    next(data) { /* process wallet sync events */ },
    error(err) { console.error(err); },
    complete() {},
  },
);

// Step 3: cleanup session when done
await fetch(indexerHttpUrl, {
  method: 'POST',
  headers: { 'content-type': 'application/json' },
  body: JSON.stringify({
    query: `mutation { disconnect(sessionId: "${sessionId}") }`,
  }),
});

async function pollForContractState(
  indexerUrl: string,
  contractAddress: string,
  options: { maxAttempts?: number; intervalMs?: number } = {},
): Promise<string | null> {
  const { maxAttempts = 30, intervalMs = 2000 } = options;

  for (let i = 0; i < maxAttempts; i++) {
    const data = await gqlQuery(indexerUrl, `
      query($address: HexEncoded!) {
        contractAction(address: $address) { state }
      }
    `, { address: contractAddress });

    if (data?.contractAction?.state) return data.contractAction.state;

    await new Promise(r => setTimeout(r, intervalMs));
  }
  return null;
}

// Usage after deploy
const deployed = await deployContract(providers, { ... });
const address = deployed.deployTxData.public.contractAddress;
const stateHex = await pollForContractState(config.indexerHttp, address);
if (!stateHex) throw new Error('Contract not found after deploy — indexer lag');