CardanoWatchClient Error: Unexpected block chain response (expected "cardano", saw "<none>")

[beastmankojak]

I'm trying to use the CardanoWatchClient to watch for transactions involving a policyId. However, whenever I get a transaction from WatchService/WatchTx, I end up with this error:

~/projects/lobsvr/indexer-testing/node_modules/.pnpm/@utxorpc+sdk@0.8.0_@bufbuild+protobuf@1.10.1/node_modules/@utxorpc/sdk/src/cardano.ts:63
        throw new Error(`Unexpected block chain response (expected "cardano", saw "${response.action.value.block?.chain?.case ?? "<none>"}")`);
              ^

Error: Unexpected block chain response (expected "cardano", saw "<none>")
    at toTxEvent (~/projects/lobsvr/indexer-testing/node_modules/.pnpm/@utxorpc+sdk@0.8.0_@bufbuild+protobuf@1.10.1/node_modules/@utxorpc/sdk/src/cardano.ts:63:15)
    at WatchClient.watchTxByPredicate (~/projects/lobsvr/indexer-testing/node_modules/.pnpm/@utxorpc+sdk@0.8.0_@bufbuild+protobuf@1.10.1/node_modules/@utxorpc/sdk/src/cardano.ts:487:13)
    at process.processTicksAndRejections (node:internal/process/task_queues:104:5)
    at async WatchClient.watchTxByMatch (~/projects/lobsvr/indexer-testing/node_modules/.pnpm/@utxorpc+sdk@0.8.0_@bufbuild+protobuf@1.10.1/node_modules/@utxorpc/sdk/src/cardano.ts:496:5)
    at async WatchClient.watchTxForAsset (~/projects/lobsvr/indexer-testing/node_modules/.pnpm/@utxorpc+sdk@0.8.0_@bufbuild+protobuf@1.10.1/node_modules/@utxorpc/sdk/src/cardano.ts:534:5)
    at async <anonymous> (~/projects/lobsvr/indexer-testing/src/utxorpc.ts:56:18)

It looks like the toTxEvent function in src/cardano.ts is checking for a Block, but we only ever get a Transaction from the service.

function toTxEvent(response: watch.WatchTxResponse): TxEvent {
  switch (response.action.case) {
    case "apply":
    case "undo":
      if (response.action.value.chain.case !== "cardano") {
        throw new Error(`Unexpected tx chain response (expected "cardano", saw "${response.action.value.chain.case}")`);
      }
      if (response.action.value.block?.chain?.case !== "cardano") {
        // This code always triggers, because this is a Transaction Event, not a Block Event
        throw new Error(`Unexpected block chain response (expected "cardano", saw "${response.action.value.block?.chain?.case ?? "<none>"}")`);
      }
      return {
        action: response.action.case,
        Tx: response.action.value.chain.value,
        Block: response.action.value.block.chain.value,
      }

Can we just get rid of the check for a Block here, and then only return the action and Tx? It seems like we don't need the Block if we're just dealing with a Transation Event.

[beastmankojak]

@SupernaviX can you comment on this? It looks like you added the code that checks for a Block, as well as a PR that adds the Block response to Dolos, though it hasn't been merged yet. I don't see a Block field in the utxorpc spec version 0.18.1 either, so this change seems out of spec?

I'm seeing this error when running against Dolos version 1.0.0-rc.10 - 2026-02-17.