feat(balance): 레벨 기반 장비 손실 확률 시스템

- 저레벨 사망 스파이럴 방지
- 장비 손실 확률 = (레벨 - 5) * 10%
  - Lv 1~5: 0% (절대 안전)
  - Lv 6: 10%
  - Lv 10: 50%
  - Lv 15+: 100%
- 디버그 로그 추가

lib/src/core/engine/combat_tick_service.dart

@@ -265,79 +265,73 @@ class CombatTickService {
       return null;
     }
 
-    // 우선순위 1: HP 물약 (HP <= 30%)
-    final hpRatio = playerStats.hpCurrent / playerStats.hpMax;
-    if (hpRatio <= PotionService.emergencyHpThreshold) {
-      final hpPotion = potionService.selectEmergencyHpPotion(
+    // 우선순위 1: HP 물약 (소모된 HP >= 물약 회복량)
+    final hpPotion = potionService.selectEmergencyHpPotion(
+      currentHp: playerStats.hpCurrent,
+      maxHp: playerStats.hpMax,
+      inventory: potionInventory,
+      playerLevel: playerLevel,
+    );
+
+    if (hpPotion != null) {
+      final result = potionService.usePotion(
+        potionId: hpPotion.id,
+        inventory: potionInventory,
         currentHp: playerStats.hpCurrent,
         maxHp: playerStats.hpMax,
-        inventory: potionInventory,
-        playerLevel: playerLevel,
+        currentMp: playerStats.mpCurrent,
+        maxMp: playerStats.mpMax,
       );
 
-      if (hpPotion != null) {
-        final result = potionService.usePotion(
-          potionId: hpPotion.id,
-          inventory: potionInventory,
-          currentHp: playerStats.hpCurrent,
-          maxHp: playerStats.hpMax,
-          currentMp: playerStats.mpCurrent,
-          maxMp: playerStats.mpMax,
+      if (result.success) {
+        return (
+          playerStats: playerStats.copyWith(hpCurrent: result.newHp),
+          lastPotionUsedMs: timestamp,
+          potionInventory: result.newInventory!,
+          events: [
+            CombatEvent.playerPotion(
+              timestamp: timestamp,
+              potionName: hpPotion.name,
+              healAmount: result.healedAmount,
+              isHp: true,
+            ),
+          ],
         );
-
-        if (result.success) {
-          return (
-            playerStats: playerStats.copyWith(hpCurrent: result.newHp),
-            lastPotionUsedMs: timestamp,
-            potionInventory: result.newInventory!,
-            events: [
-              CombatEvent.playerPotion(
-                timestamp: timestamp,
-                potionName: hpPotion.name,
-                healAmount: result.healedAmount,
-                isHp: true,
-              ),
-            ],
-          );
-        }
       }
     }
 
-    // 우선순위 2: MP 물약 (MP <= 50%)
-    final mpRatio = playerStats.mpCurrent / playerStats.mpMax;
-    if (mpRatio <= PotionService.emergencyMpThreshold) {
-      final mpPotion = potionService.selectEmergencyMpPotion(
+    // 우선순위 2: MP 물약 (소모된 MP >= 물약 회복량)
+    final mpPotion = potionService.selectEmergencyMpPotion(
+      currentMp: playerStats.mpCurrent,
+      maxMp: playerStats.mpMax,
+      inventory: potionInventory,
+      playerLevel: playerLevel,
+    );
+
+    if (mpPotion != null) {
+      final result = potionService.usePotion(
+        potionId: mpPotion.id,
+        inventory: potionInventory,
+        currentHp: playerStats.hpCurrent,
+        maxHp: playerStats.hpMax,
         currentMp: playerStats.mpCurrent,
         maxMp: playerStats.mpMax,
-        inventory: potionInventory,
-        playerLevel: playerLevel,
       );
 
-      if (mpPotion != null) {
-        final result = potionService.usePotion(
-          potionId: mpPotion.id,
-          inventory: potionInventory,
-          currentHp: playerStats.hpCurrent,
-          maxHp: playerStats.hpMax,
-          currentMp: playerStats.mpCurrent,
-          maxMp: playerStats.mpMax,
+      if (result.success) {
+        return (
+          playerStats: playerStats.copyWith(mpCurrent: result.newMp),
+          lastPotionUsedMs: timestamp,
+          potionInventory: result.newInventory!,
+          events: [
+            CombatEvent.playerPotion(
+              timestamp: timestamp,
+              potionName: mpPotion.name,
+              healAmount: result.healedAmount,
+              isHp: false,
+            ),
+          ],
         );
-
-        if (result.success) {
-          return (
-            playerStats: playerStats.copyWith(mpCurrent: result.newMp),
-            lastPotionUsedMs: timestamp,
-            potionInventory: result.newInventory!,
-            events: [
-              CombatEvent.playerPotion(
-                timestamp: timestamp,
-                potionName: mpPotion.name,
-                healAmount: result.healedAmount,
-                isHp: false,
-              ),
-            ],
-          );
-        }
       }
     }
 

lib/src/core/engine/potion_service.dart

@@ -13,12 +13,6 @@ class PotionService {
   /// 글로벌 물약 쿨타임 (1배속 기준 3초)
   static const int globalPotionCooldownMs = 3000;
 
-  /// 긴급 물약 사용 HP 임계치 (30%)
-  static const double emergencyHpThreshold = 0.30;
-
-  /// 긴급 물약 사용 MP 임계치 (50%)
-  static const double emergencyMpThreshold = 0.50;
-
   // ============================================================================
   // 물약 사용 가능 여부
   // ============================================================================
@@ -104,7 +98,7 @@ class PotionService {
 
   /// 긴급 HP 물약 선택
   ///
-  /// HP가 임계치 이하일 때 사용할 최적의 물약 선택
+  /// 소모된 HP >= 물약 회복량이면 사용할 최적의 물약 선택
   /// [currentHp] 현재 HP
   /// [maxHp] 최대 HP
   /// [inventory] 물약 인벤토리
@@ -115,9 +109,8 @@ class PotionService {
     required PotionInventory inventory,
     required int playerLevel,
   }) {
-    // 임계치 체크
-    final hpRatio = currentHp / maxHp;
-    if (hpRatio > emergencyHpThreshold) return null;
+    final hpLost = maxHp - currentHp;
+    if (hpLost <= 0) return null;
 
     // 적정 티어 계산
     final targetTier = PotionData.tierForLevel(playerLevel);
@@ -126,7 +119,10 @@ class PotionService {
     for (var tier = targetTier; tier >= 1; tier--) {
       final potion = PotionData.getHpPotionByTier(tier);
       if (potion != null && inventory.hasPotion(potion.id)) {
-        return potion;
+        final healAmount = potion.calculateHeal(maxHp);
+        if (hpLost >= healAmount) {
+          return potion;
+        }
       }
     }
 
@@ -134,7 +130,10 @@ class PotionService {
     for (var tier = targetTier + 1; tier <= 5; tier++) {
       final potion = PotionData.getHpPotionByTier(tier);
       if (potion != null && inventory.hasPotion(potion.id)) {
-        return potion;
+        final healAmount = potion.calculateHeal(maxHp);
+        if (hpLost >= healAmount) {
+          return potion;
+        }
       }
     }
 
@@ -143,16 +142,15 @@ class PotionService {
 
   /// 긴급 MP 물약 선택
   ///
-  /// MP가 임계치 이하일 때 사용할 최적의 물약 선택
+  /// 소모된 MP >= 물약 회복량이면 사용할 최적의 물약 선택
   Potion? selectEmergencyMpPotion({
     required int currentMp,
     required int maxMp,
     required PotionInventory inventory,
     required int playerLevel,
   }) {
-    // 임계치 체크
-    final mpRatio = currentMp / maxMp;
-    if (mpRatio > emergencyMpThreshold) return null;
+    final mpLost = maxMp - currentMp;
+    if (mpLost <= 0) return null;
 
     // 적정 티어 계산
     final targetTier = PotionData.tierForLevel(playerLevel);
@@ -161,7 +159,10 @@ class PotionService {
     for (var tier = targetTier; tier >= 1; tier--) {
       final potion = PotionData.getMpPotionByTier(tier);
       if (potion != null && inventory.hasPotion(potion.id)) {
-        return potion;
+        final healAmount = potion.calculateHeal(maxMp);
+        if (mpLost >= healAmount) {
+          return potion;
+        }
       }
     }
 
@@ -169,7 +170,10 @@ class PotionService {
     for (var tier = targetTier + 1; tier <= 5; tier++) {
       final potion = PotionData.getMpPotionByTier(tier);
       if (potion != null && inventory.hasPotion(potion.id)) {
-        return potion;
+        final healAmount = potion.calculateHeal(maxMp);
+        if (mpLost >= healAmount) {
+          return potion;
+        }
       }
     }
 

lib/src/core/engine/progress_service.dart

@@ -974,40 +974,50 @@ class ProgressService {
     ItemRarity? lostItemRarity;
 
     if (!isBossDeath) {
-      // 무기(슬롯 0)를 제외한 장착된 장비 중 1개를 제물로 삭제
-      final equippedNonWeaponSlots = <int>[];
-      for (var i = 1; i < Equipment.slotCount; i++) {
-        final item = state.equipment.getItemByIndex(i);
-        // 디버그: 장비 슬롯 상태 확인
-        // ignore: avoid_print
-        print('[Death] Slot $i: "${item.name}" isEmpty=${item.isEmpty}');
-        if (item.isNotEmpty) {
-          equippedNonWeaponSlots.add(i);
-        }
-      }
-      // 디버그: 장착된 슬롯 목록
+      // 레벨 기반 장비 손실 확률 계산
+      // Lv 1~5: 0%, Lv 6: 10%, Lv 10: 50%, Lv 15+: 100%
+      final level = state.traits.level;
+      final lossChancePercent = ((level - 5) * 10).clamp(0, 100);
+      final roll = state.rng.nextInt(100); // 0~99
+      final shouldLoseEquipment = roll < lossChancePercent;
+
       // ignore: avoid_print
-      print('[Death] equippedNonWeaponSlots: $equippedNonWeaponSlots');
+      print('[Death] Lv$level lossChance=$lossChancePercent% roll=$roll '
+          'shouldLose=$shouldLoseEquipment');
 
-      if (equippedNonWeaponSlots.isNotEmpty) {
-        lostCount = 1;
-        // 랜덤하게 1개 슬롯 선택
-        final sacrificeIndex =
-            equippedNonWeaponSlots[state.rng.nextInt(
-              equippedNonWeaponSlots.length,
-            )];
+      if (shouldLoseEquipment) {
+        // 무기(슬롯 0)를 제외한 장착된 장비 중 1개를 제물로 삭제
+        final equippedNonWeaponSlots = <int>[];
+        for (var i = 1; i < Equipment.slotCount; i++) {
+          final item = state.equipment.getItemByIndex(i);
+          if (item.isNotEmpty) {
+            equippedNonWeaponSlots.add(i);
+          }
+        }
 
-        // 제물로 바칠 아이템 정보 저장
-        final lostItem = state.equipment.getItemByIndex(sacrificeIndex);
-        lostItemName = lostItem.name;
-        lostItemSlot = EquipmentSlot.values[sacrificeIndex];
-        lostItemRarity = lostItem.rarity;
+        if (equippedNonWeaponSlots.isNotEmpty) {
+          lostCount = 1;
+          // 랜덤하게 1개 슬롯 선택
+          final sacrificeIndex =
+              equippedNonWeaponSlots[state.rng.nextInt(
+                equippedNonWeaponSlots.length,
+              )];
 
-        // 해당 슬롯을 빈 장비로 교체
-        newEquipment = newEquipment.setItemByIndex(
-          sacrificeIndex,
-          EquipmentItem.empty(lostItemSlot),
-        );
+          // 제물로 바칠 아이템 정보 저장
+          final lostItem = state.equipment.getItemByIndex(sacrificeIndex);
+          lostItemName = lostItem.name;
+          lostItemSlot = EquipmentSlot.values[sacrificeIndex];
+          lostItemRarity = lostItem.rarity;
+
+          // 해당 슬롯을 빈 장비로 교체
+          newEquipment = newEquipment.setItemByIndex(
+            sacrificeIndex,
+            EquipmentItem.empty(lostItemSlot),
+          );
+
+          // ignore: avoid_print
+          print('[Death] Lost item: $lostItemName (slot: $lostItemSlot)');
+        }
       }
     }