diff --git a/category/execution/monad/chain/monad_chain.hpp b/category/execution/monad/chain/monad_chain.hpp
index cd924ce8d..56b4fd27d 100644
--- a/category/execution/monad/chain/monad_chain.hpp
+++ b/category/execution/monad/chain/monad_chain.hpp
@@ -49,6 +49,9 @@ struct MonadChainContext
     std::vector<std::vector<std::optional<Address>>> const &authorities;
 };
 
+static_assert(sizeof(MonadChainContext) == 40);
+static_assert(alignof(MonadChainContext) == 8);
+
 struct MonadChain : Chain
 {
     virtual evmc_revision
diff --git a/cmd/monad/runloop_ethereum.cpp b/cmd/monad/runloop_ethereum.cpp
index 92564d4d6..166be6db3 100644
--- a/cmd/monad/runloop_ethereum.cpp
+++ b/cmd/monad/runloop_ethereum.cpp
@@ -79,9 +79,8 @@ void log_tps(
 
 // Process a single historical Ethereum block
 template <Traits traits>
-Result<void> process_ethereum_block(
-    Chain const &chain, Db &db, vm::VM &vm,
-    BlockHashBufferFinalized &block_hash_buffer,
+Result<BlockHeader> process_ethereum_block(
+    Chain const &chain, Db &db, vm::VM &vm, BlockHashBuffer &block_hash_buffer,
     fiber::PriorityPool &priority_pool, Block &block, bytes32_t const &block_id,
     bytes32_t const &parent_block_id, bool const enable_tracing)
 {
@@ -151,7 +150,7 @@ Result<void> process_ethereum_block(
     block_state.log_debug();
     auto const commit_begin = std::chrono::steady_clock::now();
     block_state.commit(
-        bytes32_t{block.header.number},
+        block_id,
         block.header,
         receipts,
         call_frames,
@@ -164,7 +163,7 @@ Result<void> process_ethereum_block(
             std::chrono::steady_clock::now() - commit_begin);
 
     // Post-commit validation of header, with Merkle root fields filled in
-    auto const output_header = db.read_eth_header();
+    BlockHeader const output_header = db.read_eth_header();
     BOOST_OUTCOME_TRY(
         chain.validate_output_header(block.header, output_header));
 
@@ -172,9 +171,6 @@ Result<void> process_ethereum_block(
     // block hash to append to the circular hash buffer
     db.finalize(block.header.number, block_id);
     db.update_verified_block(block.header.number);
-    auto const eth_block_hash =
-        to_bytes(keccak256(rlp::encode_block_header(output_header)));
-    block_hash_buffer.set(block.header.number, eth_block_hash);
 
     // Emit the block metrics log line
     [[maybe_unused]] auto const block_time =
@@ -209,7 +205,7 @@ Result<void> process_ethereum_block(
         vm.print_and_reset_block_counts(),
         vm.print_compiler_stats());
 
-    return outcome_e::success();
+    return output_header;
 }
 
 MONAD_ANONYMOUS_NAMESPACE_END
@@ -245,7 +241,7 @@ Result<std::pair<uint64_t, uint64_t>> runloop_ethereum(
         evmc_revision const rev =
             chain.get_revision(block.header.number, block.header.timestamp);
 
-        BOOST_OUTCOME_TRY([&] {
+        BOOST_OUTCOME_TRY(BlockHeader const output_header, [&] {
             SWITCH_EVM_TRAITS(
                 process_ethereum_block,
                 chain,
@@ -260,6 +256,10 @@ Result<std::pair<uint64_t, uint64_t>> runloop_ethereum(
             MONAD_ABORT_PRINTF("unhandled rev switch case: %d", rev);
         }());
 
+        bytes32_t const eth_block_hash =
+            to_bytes(keccak256(rlp::encode_block_header(output_header)));
+        block_hash_buffer.set(block.header.number, eth_block_hash);
+
         ntxs += block.transactions.size();
         batch_num_txs += block.transactions.size();
         total_gas += block.header.gas_used;
diff --git a/cmd/monad/runloop_monad.cpp b/cmd/monad/runloop_monad.cpp
index aeda83b76..2f844cfea 100644
--- a/cmd/monad/runloop_monad.cpp
+++ b/cmd/monad/runloop_monad.cpp
@@ -183,28 +183,26 @@ Result<BlockExecOutput> propose_block(
             return TransactionError::MissingSender;
         }
     }
-    ankerl::unordered_dense::segmented_set<Address> senders_and_authorities;
+
+    BOOST_OUTCOME_TRY(static_validate_monad_senders<traits>(senders));
+    auto [entry, success] = block_cache.emplace(
+        block_id,
+        BlockCacheEntry{
+            .block_number = block.header.number,
+            .parent_id = consensus_header.parent_id(),
+            .senders_and_authorities = {}});
+    MONAD_ASSERT(success, "should never be processing duplicate block");
     for (Address const &sender : senders) {
-        senders_and_authorities.insert(sender);
+        entry->second.senders_and_authorities.insert(sender);
     }
     for (std::vector<std::optional<Address>> const &authorities :
          recovered_authorities) {
         for (std::optional<Address> const &authority : authorities) {
             if (authority.has_value()) {
-                senders_and_authorities.insert(authority.value());
+                entry->second.senders_and_authorities.insert(authority.value());
             }
         }
     }
-    MONAD_ASSERT(block_cache
-                     .emplace(
-                         block_id,
-                         BlockCacheEntry{
-                             .block_number = block.header.number,
-                             .parent_id = consensus_header.parent_id(),
-                             .senders_and_authorities =
-                                 std::move(senders_and_authorities)})
-                     .second);
-    BOOST_OUTCOME_TRY(static_validate_monad_senders<traits>(senders));
 
     // Create call frames vectors for tracers
     std::vector<std::vector<CallFrame>> call_frames{block.transactions.size()};