[F-2026-17740] - KV indexer path misses derived transactions

[AryaLanjewar3005]

[F-2026-17740] - KV indexer path misses derived transactions

Issue

The KV indexer only indexes standard MsgEthereumTx transactions — EVM executions submitted directly via Ethereum RPC. Derived transactions (EVM calls triggered internally by Cosmos modules such as IBC callbacks, governance, and ERC20 hooks) are never written to the index because they do not appear in block.Txs and do not carry the ExtensionOptionsEthereumTx extension option that isEthTx requires.

File: indexer/kv_indexer.go

if !isEthTx(tx) {
    continue  // derived txs always skipped — never indexed
}

At query time, GetTxByEthHash delegates to the KV indexer when one is configured and treats any error as a hard failure with no fallback:

File: rpc/backend/tx_info.go

if b.indexer != nil {
    txRes, err := b.indexer.GetByTxHash(hash)
    if err != nil {
        return nil, nil, err  // derived tx miss → error returned, fallback never reached
    }
    return txRes, nil, nil
}

// fallback to tendermint event search — unreachable when indexer is set

A working fallback path already exists below the indexer block. It searches Tendermint's event index using the ethereum_tx.ethereumTxHash attribute, which derived transactions do emit. On nodes without the KV indexer this path resolves derived txs correctly. On nodes with the KV indexer it is structurally unreachable.

Impact

• Nodes with KV indexer enabled return errors for eth_getTransactionByHash, eth_getTransactionReceipt, and related APIs when called with a derived transaction hash.
• Nodes without the KV indexer resolve the same hash correctly.
• This deployment-dependent inconsistency breaks integrators, block explorers, and indexing infrastructure that assume uniform transaction availability across node configurations.

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Solution

Change the error handling in GetTxByEthHash and GetTxByEthHashAndMsgIndex so that a KV indexer miss is treated as a cache miss rather than a hard failure. When GetByTxHash returns an error, fall through to the existing Tendermint event-query reconstruction path instead of propagating the error.

if b.indexer != nil {
    txRes, err := b.indexer.GetByTxHash(hash)
    if err == nil {
        return txRes, nil, nil  // cache hit — fast path preserved
    }
    // indexer miss or no derived-tx metadata — fall through to event-query reconstruction
}

// fallback to tendermint event search — now reachable for any miss

Behavior after fix

Node config	Transaction type	Result
No KV indexer	Standard Eth Tx	Found via Tendermint event search
No KV indexer	Derived Tx	Found via Tendermint event search
KV indexer enabled	Standard Eth Tx	Found in KV index (fast path, unchanged)
KV indexer enabled	Derived Tx	KV miss → fallback → found via Tendermint event search

Limitation

The fallback relies on Tendermint's event index. On nodes that prune historical event data, derived transactions older than the pruning window remain unresolvable. A complete fix requires also indexing derived transactions in the KV store during IndexBlock by scanning txResults[i].Events for EventTypeEthereumTx events carrying a DerivedTxType marker — this would give derived txs the same pruning-resistant durability as standard Eth txs.

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