feat(via_btc_client): implement Largest-First UTXO selection

core/lib/config/src/configs/via_btc_sender.rs

@@ -35,6 +35,36 @@ pub struct ViaBtcSenderConfig {
 
     /// The required time (seconds) to wait before create a proof inscription.
     pub block_time_to_proof: Option<u32>,
+
+    /// Minimum inscription output value to stay comfortably above dust-like policy floors.
+    pub min_inscription_output_sats: Option<u64>,
+
+    /// Minimum reusable change output value.
+    pub min_change_output_sats: Option<u64>,
+
+    /// Whether unconfirmed reveal-change outputs from the in-memory inscriber context may be reused.
+    pub allow_unconfirmed_change_reuse: Option<bool>,
+
+    /// Minimum feerate for normal inscription construction.
+    pub min_feerate_sat_vb: Option<u64>,
+
+    /// Minimum feerate when the sender is already operating on a pending chain.
+    pub min_feerate_chained_sat_vb: Option<u64>,
+
+    /// Maximum feerate cap to avoid runaway overpay behavior.
+    pub max_feerate_sat_vb: Option<u64>,
+
+    /// Additional sat/vB step applied as pending chain depth grows.
+    pub escalation_step_sat_vb: Option<u64>,
+
+    /// Minimum age before attempting a replacement / re-broadcast for a stuck inscription.
+    pub escalation_interval_sec: Option<u64>,
+
+    /// Max number of pending inscriptions in context before pausing new sends.
+    pub max_pending_chain_depth: Option<u32>,
+
+    /// Do not send new inscriptions when trusted (confirmed) balance goes below this threshold.
+    pub min_spendable_balance_sats: Option<u64>,
 }
 
 impl ViaBtcSenderConfig {
@@ -60,6 +90,46 @@ impl ViaBtcSenderConfig {
     pub fn stuck_inscription_block_number(&self) -> u32 {
         self.stuck_inscription_block_number.unwrap_or(6)
     }
+
+    pub fn min_inscription_output_sats(&self) -> u64 {
+        self.min_inscription_output_sats.unwrap_or(600)
+    }
+
+    pub fn min_change_output_sats(&self) -> u64 {
+        self.min_change_output_sats.unwrap_or(1_000)
+    }
+
+    pub fn allow_unconfirmed_change_reuse(&self) -> bool {
+        self.allow_unconfirmed_change_reuse.unwrap_or(false)
+    }
+
+    pub fn min_feerate_sat_vb(&self) -> u64 {
+        self.min_feerate_sat_vb.unwrap_or(8)
+    }
+
+    pub fn min_feerate_chained_sat_vb(&self) -> u64 {
+        self.min_feerate_chained_sat_vb.unwrap_or(20)
+    }
+
+    pub fn max_feerate_sat_vb(&self) -> u64 {
+        self.max_feerate_sat_vb.unwrap_or(80)
+    }
+
+    pub fn escalation_step_sat_vb(&self) -> u64 {
+        self.escalation_step_sat_vb.unwrap_or(5)
+    }
+
+    pub fn escalation_interval_sec(&self) -> u64 {
+        self.escalation_interval_sec.unwrap_or(900)
+    }
+
+    pub fn max_pending_chain_depth(&self) -> u32 {
+        self.max_pending_chain_depth.unwrap_or(3)
+    }
+
+    pub fn min_spendable_balance_sats(&self) -> u64 {
+        self.min_spendable_balance_sats.unwrap_or(2_000)
+    }
 }
 
 impl ViaBtcSenderConfig {
@@ -76,6 +146,29 @@ impl ViaBtcSenderConfig {
             block_time_to_commit: None,
             block_time_to_proof: None,
             stuck_inscription_block_number: None,
+            min_inscription_output_sats: None,
+            min_change_output_sats: None,
+            allow_unconfirmed_change_reuse: None,
+            min_feerate_sat_vb: None,
+            min_feerate_chained_sat_vb: None,
+            max_feerate_sat_vb: None,
+            escalation_step_sat_vb: None,
+            escalation_interval_sec: None,
+            max_pending_chain_depth: None,
+            min_spendable_balance_sats: None,
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::ViaBtcSenderConfig;
+
+    #[test]
+    fn test_guardrail_defaults() {
+        let config = ViaBtcSenderConfig::for_tests();
+
+        assert_eq!(config.max_pending_chain_depth(), 3);
+        assert_eq!(config.min_spendable_balance_sats(), 2_000);
+    }
+}

core/lib/via_btc_client/src/inscriber/internal_type.rs

@@ -6,6 +6,7 @@ pub struct CommitTxInputRes {
     pub unlocked_value: Amount,
     pub inputs_count: u32,
     pub utxo_amounts: Vec<Amount>,
+    pub fee_rate: u64,
 }
 
 #[derive(Debug)]
@@ -22,6 +23,7 @@ pub struct RevealTxInputRes {
     pub prev_outs: Vec<TxOut>,
     pub unlock_value: Amount,
     pub control_block: ControlBlock,
+    pub fee_rate: u64,
 }
 
 #[derive(Debug)]