feat(wallet): Use mempool histogram for fee estimation (#358)

* feat(wallet): Use mempool.space as a secondary fee estimation source

* fix: warn if mempool client cannot be instantiated

* make clippy happy

* nitpick: rename clippy_check to clippy in justfile

* rename `estimate_fee_rate_from_mempool` to `estimate_fee_rate_from_histogram` for clarity

* dprint fmt

* make clippy happy

* change teacing level back to debug!

* change log levels

* refactors

* refactor: estimate_fee and min_relay_fee

* serde camel case

Co-authored-by: Byron Hambly <[email protected]>

* refactors

* Add comments, use Weight struct where possible

* fmt, fix testrs

* dont fallback to bitcoin::MAX, fail instead

* make mempool space optional

* fmt

* refactor: use estimate_fee(...) in max_giveable(...)

* refactor max_giveable(...)

* refactor max_giveeable to return fee as well, remove safety margin for fee

* fix compile

* fmtr

* fix(integration test): Use pre-calculated cancel / punish fees for assert_alice_punished

* fix(integration test): Use real fees for asserts

* sync wallet before transaction_fee call

* split send_to_address into sweep_balance_to_address_dynamic_fee

---------

Co-authored-by: Byron Hambly <[email protected]>

Author: binarybaron

CHANGELOG.md

@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- We add a safety margin of 25% to the Bitcoin fee estimation. This ensures pre-signed transactions will get confirmed in time.
+- The Bitcoin fee estimation is now more accurate. It uses a combination of `estimatesmartfee` from Bitcoin Core and `mempool.get_fee_histogram` from Electrum to ensure our distance from the mempool tip is appropriate. If our Electrum server doesn't support fee estimation, we use the mempool.space API. The mempool space API can be disabled using the `bitcoin.use_mempool_space_fee_estimation` option in the config file. It defaults to `true`.
 
 ## [1.1.2] - 2025-05-24
 

dprint.json

@@ -25,4 +25,4 @@
     "https://plugins.dprint.dev/exec-0.3.5.json@d687dda57be0fe9a0088ccdaefa5147649ff24127d8b3ea227536c68ee7abeab",
     "https://plugins.dprint.dev/prettier-0.26.6.json@0118376786f37496e41bb19dbcfd1e7214e2dc859a55035c5e54d1107b4c9c57"
   ]
-}
+}

justfile

@@ -50,7 +50,7 @@ update_submodules:
 	cd monero-sys && git submodule update --init --recursive --force
 
 # Run clippy checks
-clippy_check:
+clippy:
 	cargo clippy --workspace --all-targets --all-features -- -D warnings
 
 # Check the bindings for the Tauri API
@@ -71,4 +71,4 @@ fmt:
 
 # Sometimes you have to prune the docker network to get the integration tests to work
 docker-prune-network:
-	docker network prune -f
+	docker network prune -f

swap/proptest-regressions/bitcoin/wallet.txt

@@ -5,3 +5,6 @@
 # It is recommended to check this file in to source control so that
 # everyone who runs the test benefits from these saved cases.
 cc 849f8b01f49fc9a913100203698a9151d8de8a37564e1d3b1e3b4169e192f58a # shrinks to funding_amount = 290250686, num_utxos = 3, sats_per_vb = 75.35638, key = ExtendedPrivKey { network: Regtest, depth: 0, parent_fingerprint: 00000000, child_number: Normal { index: 0 }, private_key: [private key data], chain_code: 0b7a29ca6990bbc9b9187c1d1a07e2cf68e32f5ce55d2df01edf8a4ac2ee2a4b }, alice = Point<Normal,Public,NonZero>(0299a8c6a662e2e9e8ee7c6889b75a51c432812b4bf70c1d76eace63abc1bdfb1b), bob = Point<Normal,Public,NonZero>(027165b1f9924030c90d38c511da0f4397766078687997ed34d6ef2743d2a7bbed)
+cc ec2c53bbf967d46a4e9a394da96f8089ea77dcca794dec9fcc13c5a7141eb929 # shrinks to funding_amount = 271331, num_utxos = 4, sats_per_vb = 308, key = Xpriv { network: Test, depth: 0, parent_fingerprint: 00000000, child_number: Normal { index: 0 }, private_key: SecretKey(#dc659542f09c329f), chain_code: c94a49bbee951f7f7401c801db73c23cf17b0b3aa2f6246a8616fe2205a6ca51 }, alice = Point<Normal,Public,NonZero>(0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798), bob = Point<Normal,Public,NonZero>(02c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5)
+cc 2062fe113880e48af4d170fca9a2690e57a55f8985f86a66bd53e8bbe5c62dbd # shrinks to funding_amount = 3000, num_utxos = 1, sats_per_vb = 7, key = Xpriv { network: Test, depth: 0, parent_fingerprint: 00000000, child_number: Normal { index: 0 }, private_key: SecretKey(#dc659542f09c329f), chain_code: c94a49bbee951f7f7401c801db73c23cf17b0b3aa2f6246a8616fe2205a6ca51 }, alice = Point<Normal,Public,NonZero>(0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798), bob = Point<Normal,Public,NonZero>(02c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5)
+cc 381f4c0a72579c36107b0fd7a5b9c8aad2f02c0f9908b3a137b71ff05e7d8d33 # shrinks to funding_amount = 3000, num_utxos = 1, sats_per_vb = 7, key = Xpriv { network: Test, depth: 0, parent_fingerprint: 00000000, child_number: Normal { index: 0 }, private_key: SecretKey(#dc659542f09c329f), chain_code: c94a49bbee951f7f7401c801db73c23cf17b0b3aa2f6246a8616fe2205a6ca51 }, alice = Point<Normal,Public,NonZero>(0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798), bob = Point<Normal,Public,NonZero>(02c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5)

swap/src/asb/config.rs

@@ -185,6 +185,12 @@ pub struct Bitcoin {
     pub finality_confirmations: Option<u32>,
     #[serde(with = "crate::bitcoin::network")]
     pub network: bitcoin::Network,
+    #[serde(default = "default_use_mempool_space_fee_estimation")]
+    pub use_mempool_space_fee_estimation: bool,
+}
+
+fn default_use_mempool_space_fee_estimation() -> bool {
+    true
 }
 
 #[derive(Clone, Debug, Deserialize, PartialEq, Eq, Serialize)]
@@ -377,6 +383,7 @@ pub fn query_user_for_initial_config(testnet: bool) -> Result<Config> {
             target_block,
             finality_confirmations: None,
             network: bitcoin_network,
+            use_mempool_space_fee_estimation: true,
         },
         monero: Monero {
             wallet_rpc_url: monero_wallet_rpc_url,
@@ -421,6 +428,7 @@ mod tests {
                 target_block: defaults.bitcoin_confirmation_target,
                 finality_confirmations: None,
                 network: bitcoin::Network::Testnet,
+                use_mempool_space_fee_estimation: true,
             },
             network: Network {
                 listen: vec![defaults.listen_address_tcp],
@@ -465,6 +473,7 @@ mod tests {
                 target_block: defaults.bitcoin_confirmation_target,
                 finality_confirmations: None,
                 network: bitcoin::Network::Bitcoin,
+                use_mempool_space_fee_estimation: true,
             },
             network: Network {
                 listen: vec![defaults.listen_address_tcp],
@@ -519,6 +528,7 @@ mod tests {
                 target_block: defaults.bitcoin_confirmation_target,
                 finality_confirmations: None,
                 network: bitcoin::Network::Bitcoin,
+                use_mempool_space_fee_estimation: true,
             },
             network: Network {
                 listen,

swap/src/bin/asb.rs

@@ -310,19 +310,22 @@ pub async fn main() -> Result<()> {
         Command::WithdrawBtc { amount, address } => {
             let bitcoin_wallet = init_bitcoin_wallet(&config, &seed, env_config).await?;
 
-            let amount = match amount {
-                Some(amount) => amount,
+            let withdraw_tx_unsigned = match amount {
+                Some(amount) => {
+                    bitcoin_wallet
+                        .send_to_address_dynamic_fee(address, amount, None)
+                        .await?
+                }
                 None => {
                     bitcoin_wallet
-                        .max_giveable(address.script_pubkey().len())
+                        .sweep_balance_to_address_dynamic_fee(address)
                         .await?
                 }
             };
 
-            let psbt = bitcoin_wallet
-                .send_to_address(address, amount, None)
+            let signed_tx = bitcoin_wallet
+                .sign_and_finalize(withdraw_tx_unsigned)
                 .await?;
-            let signed_tx = bitcoin_wallet.sign_and_finalize(psbt).await?;
 
             bitcoin_wallet.broadcast(signed_tx, "withdraw").await?;
         }
@@ -420,6 +423,7 @@ async fn init_bitcoin_wallet(
         })
         .finality_confirmations(env_config.bitcoin_finality_confirmations)
         .target_block(config.bitcoin.target_block)
+        .use_mempool_space_fee_estimation(config.bitcoin.use_mempool_space_fee_estimation)
         .sync_interval(env_config.bitcoin_sync_interval())
         .build()
         .await