miner: add block_max_weight to BlockCreateOptions

diff --git a/src/node/miner.cpp b/src/node/miner.cpp
index c9a491ef..41c1d997 100644
--- a/src/node/miner.cpp
+++ b/src/node/miner.cpp
@@ -78,12 +78,12 @@ void RegenerateCommitments(CBlock& block, ChainstateManager& chainman)
 
 static BlockAssembler::Options ClampOptions(BlockAssembler::Options options)
 {
-    // Apply DEFAULT_BLOCK_RESERVED_WEIGHT when the caller left it unset.
-    options.block_reserved_weight = std::clamp<size_t>(options.block_reserved_weight.value_or(DEFAULT_BLOCK_RESERVED_WEIGHT), MINIMUM_BLOCK_RESERVED_WEIGHT, MAX_BLOCK_WEIGHT);
+    // Apply DEFAULT_BLOCK_RESERVED_WEIGHT and DEFAULT_BLOCK_MAX_WEIGHT when the caller left it unset.
+    options.block_reserved_weight = std::clamp<uint64_t>(options.block_reserved_weight.value_or(DEFAULT_BLOCK_RESERVED_WEIGHT), MINIMUM_BLOCK_RESERVED_WEIGHT, MAX_BLOCK_WEIGHT);
     options.coinbase_output_max_additional_sigops = std::clamp<size_t>(options.coinbase_output_max_additional_sigops, 0, MAX_BLOCK_SIGOPS_COST);
     // Limit weight to between block_reserved_weight and MAX_BLOCK_WEIGHT for sanity:
     // block_reserved_weight can safely exceed -blockmaxweight, but the rest of the block template will be empty.
-    options.nBlockMaxWeight = std::clamp<size_t>(options.nBlockMaxWeight, *options.block_reserved_weight, MAX_BLOCK_WEIGHT);
+    options.block_max_weight = std::clamp<uint64_t>(options.block_max_weight.value_or(DEFAULT_BLOCK_MAX_WEIGHT), *options.block_reserved_weight, MAX_BLOCK_WEIGHT);
     return options;
 }
 
@@ -98,13 +98,15 @@ BlockAssembler::BlockAssembler(Chainstate& chainstate, const CTxMemPool* mempool
 void ApplyArgsManOptions(const ArgsManager& args, BlockAssembler::Options& options)
 {
     // Block resource limits
-    options.nBlockMaxWeight = args.GetIntArg("-blockmaxweight", options.nBlockMaxWeight);
+    if (!options.block_max_weight) {
+        options.block_max_weight = args.GetArg<uint64_t>("-blockmaxweight");
+    }
     if (const auto blockmintxfee{args.GetArg("-blockmintxfee")}) {
         if (const auto parsed{ParseMoney(*blockmintxfee)}) options.blockMinFeeRate = CFeeRate{*parsed};
     }
     options.print_modified_fee = args.GetBoolArg("-printpriority", options.print_modified_fee);
     if (!options.block_reserved_weight) {
-        options.block_reserved_weight = args.GetIntArg("-blockreservedweight");
+        options.block_reserved_weight = args.GetArg<uint64_t>("-blockreservedweight");
     }
 }
 
@@ -241,7 +243,7 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock()
 
 bool BlockAssembler::TestChunkBlockLimits(FeePerWeight chunk_feerate, int64_t chunk_sigops_cost) const
 {
-    if (nBlockWeight + chunk_feerate.size >= m_options.nBlockMaxWeight) {
+    if (nBlockWeight + chunk_feerate.size >= m_options.block_max_weight) {
         return false;
     }
     if (nBlockSigOpsCost + chunk_sigops_cost >= MAX_BLOCK_SIGOPS_COST) {
@@ -315,7 +317,7 @@ void BlockAssembler::addChunks()
             ++nConsecutiveFailed;
 
             if (nConsecutiveFailed > MAX_CONSECUTIVE_FAILURES && nBlockWeight +
-                    BLOCK_FULL_ENOUGH_WEIGHT_DELTA > m_options.nBlockMaxWeight) {
+                    BLOCK_FULL_ENOUGH_WEIGHT_DELTA > m_options.block_max_weight) {
                 // Give up if we're close to full and haven't succeeded in a while
                 return;
             }
diff --git a/src/node/miner.h b/src/node/miner.h
index 73003d18..b579dc68 100644
--- a/src/node/miner.h
+++ b/src/node/miner.h
@@ -80,8 +80,6 @@ private:
 
 public:
     struct Options : BlockCreateOptions {
-        // Configuration parameters for the block size
-        size_t nBlockMaxWeight{DEFAULT_BLOCK_MAX_WEIGHT};
         CFeeRate blockMinFeeRate{DEFAULT_BLOCK_MIN_TX_FEE};
         bool print_modified_fee{DEFAULT_PRINT_MODIFIED_FEE};
     };
diff --git a/src/node/mining_types.h b/src/node/mining_types.h
index 4a2ef052..30206c2e 100644
--- a/src/node/mining_types.h
+++ b/src/node/mining_types.h
@@ -40,7 +40,14 @@ struct BlockCreateOptions {
      * Cap'n Proto IPC clients currently cannot leave this field unset, so they
      * always provide a value.
      */
-    std::optional<size_t> block_reserved_weight{};
+    std::optional<uint64_t> block_reserved_weight{};
+    /**
+     * Maximum block weight, defaults to -maxblockweight
+     *
+     * block_reserved_weight can safely exceed block_max_weight, but the rest of
+     * the block template will be empty.
+     */
+    std::optional<uint64_t> block_max_weight{};
     /**
      * The maximum additional sigops which the pool will add in coinbase
      * transaction outputs.
diff --git a/src/test/fuzz/tx_pool.cpp b/src/test/fuzz/tx_pool.cpp
index 7daed723..9cada5df 100644
--- a/src/test/fuzz/tx_pool.cpp
+++ b/src/test/fuzz/tx_pool.cpp
@@ -94,7 +94,7 @@ void Finish(FuzzedDataProvider& fuzzed_data_provider, MockedTxPool& tx_pool, Cha
     WITH_LOCK(::cs_main, tx_pool.check(chainstate.CoinsTip(), chainstate.m_chain.Height() + 1));
     {
         BlockAssembler::Options options;
-        options.nBlockMaxWeight = fuzzed_data_provider.ConsumeIntegralInRange(0U, MAX_BLOCK_WEIGHT);
+        options.block_max_weight = fuzzed_data_provider.ConsumeIntegralInRange(0U, MAX_BLOCK_WEIGHT);
         options.blockMinFeeRate = CFeeRate{ConsumeMoney(fuzzed_data_provider, /*max=*/COIN)};
         auto assembler = BlockAssembler{chainstate, &tx_pool, options};
         auto block_template = assembler.CreateNewBlock();