From 0c5ba499c16d1906db8c9812b724dbe16114b381 Mon Sep 17 00:00:00 2001
From: MariusVanDerWijden <m.vanderwijden@live.de>
Date: Mon, 16 Feb 2026 17:54:11 +0100
Subject: [PATCH] eth/catalyst: fill block with txs from txpool if nil
 transactions

---
 eth/catalyst/api_testing.go | 12 ++++++++----
 miner/payload_building.go   |  4 ++--
 miner/worker.go             |  4 +++-
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/eth/catalyst/api_testing.go b/eth/catalyst/api_testing.go
index 87cceaf48f..121a7398a6 100644
--- a/eth/catalyst/api_testing.go
+++ b/eth/catalyst/api_testing.go
@@ -32,12 +32,16 @@ func RegisterTestingAPI(stack *node.Node, backend *eth.Ethereum) error {
 	return nil
 }
 
-func (api *TestingAPI) BuildBlockV1(parentHash common.Hash, payloadAttributes engine.PayloadAttributes, transactions []hexutil.Bytes, extraData *hexutil.Bytes) (*engine.ExecutionPayloadEnvelope, error) {
+func (api *TestingAPI) BuildBlockV1(parentHash common.Hash, payloadAttributes engine.PayloadAttributes, transactions *[]hexutil.Bytes, extraData *hexutil.Bytes) (*engine.ExecutionPayloadEnvelope, error) {
 	if api.eth.BlockChain().CurrentBlock().Hash() != parentHash {
 		return nil, errors.New("parentHash is not current head")
 	}
-	dec := make([][]byte, 0, len(transactions))
-	for _, tx := range transactions {
+	// If transactions is empty but not nil, build an empty block
+	// If the transactions is nil, build a block with the current transactions from the txpool
+	// If the transactions is not nil and not empty, build a block with the transactions
+	buildEmpty := transactions != nil && len(*transactions) == 0
+	dec := make([][]byte, 0, len(*transactions))
+	for _, tx := range *transactions {
 		dec = append(dec, tx)
 	}
 	txs, err := engine.DecodeTransactions(dec)
@@ -56,5 +60,5 @@ func (api *TestingAPI) BuildBlockV1(parentHash common.Hash, payloadAttributes en
 		Withdrawals:  payloadAttributes.Withdrawals,
 		BeaconRoot:   payloadAttributes.BeaconRoot,
 	}
-	return api.eth.Miner().BuildTestingPayload(args, txs, extra)
+	return api.eth.Miner().BuildTestingPayload(args, txs, buildEmpty, extra)
 }
diff --git a/miner/payload_building.go b/miner/payload_building.go
index 35e450f3e7..f876bd1841 100644
--- a/miner/payload_building.go
+++ b/miner/payload_building.go
@@ -274,7 +274,7 @@ func (miner *Miner) buildPayload(args *BuildPayloadArgs, witness bool) (*Payload
 	return payload, nil
 }
 
-func (miner *Miner) BuildTestingPayload(args *BuildPayloadArgs, transactions []*types.Transaction, extraData []byte) (*engine.ExecutionPayloadEnvelope, error) {
+func (miner *Miner) BuildTestingPayload(args *BuildPayloadArgs, transactions []*types.Transaction, empty bool, extraData []byte) (*engine.ExecutionPayloadEnvelope, error) {
 	fullParams := &generateParams{
 		timestamp:         args.Timestamp,
 		forceTime:         true,
@@ -283,7 +283,7 @@ func (miner *Miner) BuildTestingPayload(args *BuildPayloadArgs, transactions []*
 		random:            args.Random,
 		withdrawals:       args.Withdrawals,
 		beaconRoot:        args.BeaconRoot,
-		noTxs:             false,
+		noTxs:             !empty,
 		forceOverrides:    true,
 		overrideExtraData: extraData,
 		overrideTxs:       transactions,
diff --git a/miner/worker.go b/miner/worker.go
index 8aa3da2553..9e2140bd04 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -136,7 +136,9 @@ func (miner *Miner) generateWork(genParam *generateParams, witness bool) *newPay
 	work.size += uint64(genParam.withdrawals.Size())
 
 	if !genParam.noTxs {
-		if genParam.forceOverrides {
+		// If forceOverrides is true and overrideTxs is not empty, commit the override transactions
+		// otherwise, fill the block with the current transactions from the txpool
+		if genParam.forceOverrides && len(genParam.overrideTxs) > 0 {
 			if work.gasPool == nil {
 				work.gasPool = new(core.GasPool).AddGas(work.header.GasLimit)
 			}