diff --git a/src/simulator/crates/mc-turn/src/processor.rs b/src/simulator/crates/mc-turn/src/processor.rs
index 64b55397..a411fee5 100644
--- a/src/simulator/crates/mc-turn/src/processor.rs
+++ b/src/simulator/crates/mc-turn/src/processor.rs
@@ -2275,8 +2275,14 @@ impl TurnProcessor {
 
         let owner = defender_player as u8;
         let created_turn = state.turn;
-        let offer_id = state.ransom_queue.push(unit_id, captor, owner, price, created_turn);
-        let expires_turn = created_turn.saturating_add(crate::ransom::RANSOM_OFFER_DURATION_TURNS);
+        // p2-55f: use the data-driven duration from CombatBalance instead of
+        // the hardcoded const. The const remains as a fallback default for
+        // tests that construct GameState via Default and never load JSON.
+        let duration = state.combat_balance.ransom_offer_duration_turns;
+        let offer_id = state
+            .ransom_queue
+            .push_with_duration(unit_id, captor, owner, price, created_turn, duration);
+        let expires_turn = created_turn.saturating_add(duration);
 
         state.pending_capture_events.ransom_offers_created.push(UnitRansomOfferedEvent {
             turn: state.turn,
diff --git a/src/simulator/crates/mc-turn/tests/ransom.rs b/src/simulator/crates/mc-turn/tests/ransom.rs
index 38507291..62fbe5f7 100644
--- a/src/simulator/crates/mc-turn/tests/ransom.rs
+++ b/src/simulator/crates/mc-turn/tests/ransom.rs
@@ -177,3 +177,40 @@ fn pending_capture_events_is_empty_considers_new_vecs() {
     });
     assert!(!pending.is_empty(), "non-empty expired should report not-empty");
 }
+
+// ── p2-55f: end-to-end duration plumbed from CombatBalance ────────────────────
+
+#[test]
+fn push_with_duration_overrides_default_const() {
+    // p2-55f: RansomQueue::push_with_duration accepts a runtime duration,
+    // proving the const is no longer the only path. CombatBalance.ransom_offer_duration_turns
+    // flows through here when wired in processor.rs::enqueue_ransom_offer.
+    let mut q = RansomQueue::default();
+    let id = q.push_with_duration(101, 1, 2, 50, /*created*/ 10, /*duration*/ 5);
+
+    let offer = q.iter().find(|o| o.id == id).expect("offer present");
+    assert_eq!(offer.expires_turn, 15, "expires_turn = created + duration");
+
+    // Tick at turn 14 — not yet expired.
+    let early = q.tick(14);
+    assert!(early.is_empty(), "duration=5 means turn 14 is one short of expiry");
+
+    // Tick at turn 15 — drained.
+    let expired = q.tick(15);
+    assert_eq!(expired.len(), 1);
+    assert_eq!(expired[0].unit_id, 101);
+}
+
+#[test]
+fn combat_balance_default_matches_legacy_duration_const() {
+    // p2-55f: CombatBalance::default().ransom_offer_duration_turns must equal
+    // RANSOM_OFFER_DURATION_TURNS so behaviour is byte-equivalent for code
+    // paths that haven't migrated to read from CombatBalance yet.
+    use mc_turn::combat_balance::CombatBalance;
+    let cb = CombatBalance::default();
+    assert_eq!(
+        cb.ransom_offer_duration_turns,
+        RANSOM_OFFER_DURATION_TURNS,
+        "default config drift would break unmigrated callers"
+    );
+}