chore: Drop unused lookahead (#288)

Thats basically what the gap limit is doing already and its not used anyway.

Author: xdustinface

key-wallet/CLAUDE.md

@@ -187,7 +187,7 @@ let managed_account = ManagedAccount::from_account(&account);
 ```rust
 // Pre-generate addresses for performance
 let pool = &mut managed_account.account_type.receive_pool_mut()?;
-pool.ensure_addresses_generated(current_index + lookahead)?;
+pool.ensure_addresses_generated(current_index + gap_limit)?;
 ```
 
 ### 3. Transaction Checking Pattern

key-wallet/src/derivation.rs

@@ -363,8 +363,6 @@ pub struct DerivationStrategy {
     base_path: DerivationPath,
     /// Gap limit for address discovery
     gap_limit: u32,
-    /// Lookahead window
-    lookahead: u32,
 }
 
 impl DerivationStrategy {
@@ -373,7 +371,6 @@ impl DerivationStrategy {
         Self {
             base_path,
             gap_limit: 20,
-            lookahead: 20,
         }
     }
 
@@ -383,12 +380,6 @@ impl DerivationStrategy {
         self
     }
 
-    /// Set the lookahead window
-    pub fn with_lookahead(mut self, lookahead: u32) -> Self {
-        self.lookahead = lookahead;
-        self
-    }
-
     /// Derive a batch of addresses
     pub fn derive_batch<C: secp256k1::Signing>(
         &self,

key-wallet/src/managed_account/address_pool.rs

@@ -346,8 +346,6 @@ pub struct AddressPool {
     pub highest_generated: Option<u32>,
     /// Highest used index
     pub highest_used: Option<u32>,
-    /// Lookahead window for performance
-    pub lookahead_size: u32,
     /// Address type preference
     pub address_type: AddressType,
 }
@@ -389,7 +387,6 @@ impl AddressPool {
             used_indices: HashSet::new(),
             highest_generated: None,
             highest_used: None,
-            lookahead_size: gap_limit * 2,
             address_type: AddressType::P2pkh,
         }
     }
@@ -899,23 +896,6 @@ impl AddressPool {
         Ok(new_addresses)
     }
 
-    /// Generate lookahead addresses for performance
-    pub fn generate_lookahead(&mut self, key_source: &KeySource) -> Result<Vec<Address>> {
-        let target = match self.highest_used {
-            None => self.lookahead_size,
-            Some(highest) => highest + self.lookahead_size + 1,
-        };
-
-        let mut new_addresses = Vec::new();
-        while self.highest_generated.unwrap_or(0) < target {
-            let next_index = self.highest_generated.map(|h| h + 1).unwrap_or(0);
-            let address = self.generate_address_at_index(next_index, key_source, true)?;
-            new_addresses.push(address);
-        }
-
-        Ok(new_addresses)
-    }
-
     /// Set a custom label for an address
     pub fn set_address_label(&mut self, address: &Address, label: String) -> bool {
         if let Some(info) = self.address_info_mut(address) {
@@ -1040,7 +1020,6 @@ pub struct AddressPoolBuilder {
     pool_type: AddressPoolType,
     gap_limit: u32,
     network: Network,
-    lookahead_size: u32,
     address_type: AddressType,
     key_source: Option<KeySource>,
 }
@@ -1053,7 +1032,6 @@ impl AddressPoolBuilder {
             pool_type: AddressPoolType::External,
             gap_limit: DEFAULT_EXTERNAL_GAP_LIMIT,
             network: Network::Dash,
-            lookahead_size: 40,
             address_type: AddressType::P2pkh,
             key_source: None,
         }
@@ -1093,12 +1071,6 @@ impl AddressPoolBuilder {
         self
     }
 
-    /// Set the lookahead size
-    pub fn lookahead(mut self, size: u32) -> Self {
-        self.lookahead_size = size;
-        self
-    }
-
     /// Set the address type
     pub fn address_type(mut self, addr_type: AddressType) -> Self {
         self.address_type = addr_type;
@@ -1122,7 +1094,6 @@ impl AddressPoolBuilder {
             self.gap_limit,
             self.network,
         );
-        pool.lookahead_size = self.lookahead_size;
         pool.address_type = self.address_type;
 
         // Generate addresses if a key source was provided
@@ -1281,15 +1252,13 @@ mod tests {
             .internal(true)
             .gap_limit(10)
             .network(Network::Testnet)
-            .lookahead(20)
             .address_type(AddressType::P2pkh)
             .build()
             .unwrap();
 
         assert!(pool.is_internal());
         assert_eq!(pool.gap_limit, 10);
         assert_eq!(pool.network, Network::Testnet);
-        assert_eq!(pool.lookahead_size, 20);
     }
 
     #[test]