fix(rpc): derived transaction support for tracing and block responses

[AryaLanjewar3005]

Description

fix(rpc): derived transaction support for tracing and block responses

Summary

Two bugs in the 0.5.0 merge caused derived transactions (EVM executions synthesized from non-EVM Cosmos messages) to fail in two separate RPC endpoints. Both regressions are present in audit/evm-merge-inconsistent-logs but not in feat/derived-tx-evm-0.4.0.

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Bug 1 — debug_traceTransaction returns "invalid transaction v, r, s values" for derived txs

Root Cause

traceTx in x/vm/keeper/grpc_query.go calls core.TransactionToMessage(tx, signer, cfg.BaseFee) unconditionally. Derived transactions have no Ethereum signature — they are synthesized from Cosmos ABCI events and carry V=R=S=0. TransactionToMessage tries to recover the sender from these zero-value signature fields and fails with:

rpc error: code = Internal desc = invalid transaction v, r, s values

The predecessor loop (lines 552–560) was already correctly patched with an isUnsigned guard that calls unsignedTxAsMessage(from, tx, baseFee) instead of TransactionToMessage. However, traceTx itself — which processes the target transaction, not predecessors — was never updated with the same logic. The from common.Address parameter was passed in from the call site (common.BytesToAddress(req.Msg.GetFrom())) but was silently ignored inside traceTx.

Fix

x/vm/keeper/grpc_query.go — traceTx function:

Added the same isUnsigned check that already exists in the predecessor loop. When the target tx is unsigned (derived), construct the EVM message from the pre-populated from address directly instead of attempting signature recovery.

// Before
msg, err := core.TransactionToMessage(tx, signer, cfg.BaseFee)
if err != nil {
    return nil, 0, status.Error(codes.Internal, err.Error())
}
return k.traceTxWithMsg(ctx, cfg, txConfig, msg, traceConfig, commitMessage)

// After
var msg *core.Message
if isUnsigned(tx) {
    m := unsignedTxAsMessage(from, tx, cfg.BaseFee)
    msg = &m
} else {
    var err error
    msg, err = core.TransactionToMessage(tx, signer, cfg.BaseFee)
    if err != nil {
        return nil, 0, status.Error(codes.Internal, err.Error())
    }
}
return k.traceTxWithMsg(ctx, cfg, txConfig, msg, traceConfig, commitMessage)

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Bug 2 — eth_getBlockByHash returns 0 transactions when the block contains only derived txs

Root Cause

The 0.5.0 merge split block building across two functions:

• EthBlockFromCometBlock — builds a proper *ethtypes.Block. It intentionally excludes derived txs from the block body (correct: the Ethereum block trie should only contain signed native EVM txs for hash integrity). The comment at that line reads "exclude derived txs from the ETH block body".
• RPCMarshalBlock — converts the ethBlock to the JSON-RPC response. It builds the "transactions" field from block.Transactions(), which are the transactions in the ethBlock body — i.e., only native EVM txs. Derived txs are gone.

RPCBlockFromCometBlock calls both and passes a msgs slice (which does include derived txs) to RPCMarshalBlock, but RPCMarshalBlock never reads msgs — it only reads block.Transactions().

In feat/derived-tx-evm-0.4.0, RPCBlockFromCometBlock built the transaction list manually from msgs + txsAdditional, using the ABCI event-assigned hash for each derived tx. That path was lost in the 0.5.0 restructure.

Fix

rpc/backend/comet_to_eth.go — RPCBlockFromCometBlock function:

After RPCMarshalBlock returns the base block fields, override the "transactions" field with a list built from msgs + txsAdditional:

• For hash-only responses (fullTx=false): use the ABCI event hash for derived txs and ethMsg.Hash() for native EVM txs.
• For full-tx responses (fullTx=true): use NewTransactionFromMsg for native EVM txs and NewRPCTransactionFromIncompleteMsg (with the event hash) for derived txs.

This restores the behaviour from the working branch while keeping EthBlockFromCometBlock correct (derived txs remain excluded from the actual *ethtypes.Block body used for hash computation).

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Files Changed

File	Change
x/vm/keeper/grpc_query.go	Added isUnsigned guard in traceTx to use unsignedTxAsMessage for derived txs instead of failing on signature recovery
rpc/backend/comet_to_eth.go	RPCBlockFromCometBlock now overrides the "transactions" field using msgs+txsAdditional so derived txs appear in block responses

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Testing

All 11 existing BackendTestSuite/TestTraceTransaction* unit tests pass (-tags=test). The two fixes are independently verifiable by tracing a derived-tx hash and by calling eth_getBlockByHash on a block that contains only non-EVM Cosmos txs that triggered EVM executions.

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Author Checklist

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• tackled an existing issue or discussed with a team member
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• targeted the main branch