iuna

commit 8840d73382f1c8af915bafe3885fb91c44e34719
parent e59bdc98ccecd9a6b46a3bba46b1e1babf3cb000
Author: Joris Hartog <jorishartog@hotmail.com>
Date:   Fri,  7 Aug 2026 15:22:21 +0200

Make automatic burns preserve configured amount

Diffstat:
M
src/app.rs
 | 
36
+++++++++++++++++++++++++++++++++++-
M
tests/iuna.rs
 | 
21
+++++++++++++++++++++

2 files changed, 56 insertions(+), 1 deletion(-)
diff --git a/src/app.rs b/src/app.rs
@@ -1174,6 +1174,17 @@ impl NodeCore {
         })
     }
 
+    fn build_blinded_burn_with_fee_on_ledger(
+        &self,
+        ledger: &Ledger,
+        amount: Amount,
+        fee: Amount,
+    ) -> Result<BuiltBlindedTransaction> {
+        let expires_at_height = self.default_blinded_transaction_expiry_height();
+        let tx = ledger.build_burn(self.wallet.unlocked()?, amount, fee)?;
+        ledger.build_blinded_transaction(self.wallet.unlocked()?, tx, expires_at_height)
+    }
+
     fn build_transfer_with_fee_rate(
         &self,
         to: impl Into<String>,
@@ -1582,8 +1593,31 @@ impl NodeCore {
         fee_per_byte: Amount,
         balance: Amount,
     ) -> Option<BuiltBlindedTransaction> {
+        let target = self.burn_per_block.min(balance);
+        if target == 0 {
+            return None;
+        }
+        let exact_at_fee_rate =
+            self.build_blinded_burn_with_fee_rate_on_ledger(ledger, target, fee_per_byte);
+        if let Ok((built, estimate)) = exact_at_fee_rate {
+            if target
+                .checked_add(estimate.fee)
+                .is_some_and(|required| required <= balance)
+            {
+                return Some(built);
+            }
+        }
+        if self.burn_per_block <= balance {
+            let affordable_fee = balance.saturating_sub(target);
+            if let Ok(built) =
+                self.build_blinded_burn_with_fee_on_ledger(ledger, target, affordable_fee)
+            {
+                return Some(built);
+            }
+        }
+
         let mut low = 1;
-        let mut high = self.burn_per_block.min(balance);
+        let mut high = target;
         let mut best = None;
         while low <= high {
             let amount = low + (high - low) / 2;
diff --git a/tests/iuna.rs b/tests/iuna.rs
@@ -738,6 +738,27 @@ fn automatic_mining_caps_burn_to_spendable_balance_after_fee() {
 }
 
 #[test]
+fn automatic_mining_preserves_configured_burn_when_only_fee_is_short() {
+    let alice = Wallet::from_seed("auto-burn-exact-target-alice");
+    let mut allocations = BTreeMap::new();
+    allocations.insert(alice.address().to_string(), MICRO_IUNA);
+    let mut node = NodeCore::new(NodeConfig {
+        wallet: alice.clone(),
+        genesis_allocations: allocations,
+        vdf_rounds: 10,
+        burn_per_block: MICRO_IUNA,
+        burn_fee: DEFAULT_FEE_PER_BYTE,
+    });
+
+    let outcome = node.automatic_mine_once(1);
+
+    let burned = outcome.burned.as_ref().unwrap();
+    assert_eq!(burned.amount(), MICRO_IUNA);
+    assert_eq!(burned.fee(), 0);
+    assert!(outcome.block.is_some());
+}
+
+#[test]
 fn setting_burn_rate_after_running_at_zero_prepares_private_anchor_burn() {
     let alice = Wallet::from_seed("alice");
     let bob = Wallet::from_seed("bob");