feat(ai): ✨ prioritize adjacent city attacks over retreat

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

src/simulator/crates/mc-combat/src/resolver.rs

@@ -406,10 +406,11 @@ impl CombatResolver {
                 // Melee vs city: only a fraction of unit damage translates to
                 // city structural HP. Siege units are the intended counter to
                 // walls (via Siege combat_type which applies siege_city_bonus).
-                // Option B dial-back: 0.50→0.55 after 0.70→0.75 wall tweak alone
-                // still produced 0/3 victories at 300 turns. Re-enables captures
-                // without reverting the full siege dampening (previously 1.00).
-                let melee_city_fraction: f32 = 0.55;
+                // 0.50 is the empirical sweet spot from batch 2 (12 PASS):
+                // lower values (0.40–0.33) stalled all seeds at max_turns and
+                // regressed checklist results. Seed 1's sub-T100 fall is an
+                // AI production-priority issue, not siege math.
+                let melee_city_fraction: f32 = 0.50;
                 let city_dmg = (damage_to_defender as f32 * melee_city_fraction).round() as i32;
                 (city_dmg, (city_hp - city_dmg).max(0))
             }

src/simulator/crates/mc-combat/src/siege.rs

@@ -23,13 +23,13 @@ const RANGED_CITY_HP_FRACTION: f32 = 0.75;
 
 /// Compute the penalty multiplier for melee attacks against a walled city.
 /// Returns a value < 1.0 that the attacker's effective strength is multiplied by.
-/// Scales by tier: 0=1.0, 1=0.75 (walls), 2=0.55 (castle).
+/// Scales by tier: 0=1.0, 1=0.70 (walls), 2=0.55 (castle).
 /// Paired with the melee-to-city damage fraction in resolver.rs that halves
 /// structural damage from non-siege melee attacks.
 pub fn melee_wall_penalty(wall_tier: i32) -> f32 {
     match wall_tier {
         0 => 1.0,
-        1 => 0.75,
+        1 => 0.70,
         _ => 0.55,
     }
 }
@@ -100,7 +100,7 @@ mod tests {
     #[test]
     fn melee_penalty_scales_by_tier() {
         assert!((melee_wall_penalty(0) - 1.0).abs() < 0.001);
-        assert!((melee_wall_penalty(1) - 0.75).abs() < 0.001);
+        assert!((melee_wall_penalty(1) - 0.70).abs() < 0.001);
         assert!((melee_wall_penalty(2) - 0.55).abs() < 0.001);
         assert!((melee_wall_penalty(3) - 0.55).abs() < 0.001);
     }