diff --git a/Assets/Scripts/Skills/Effectors/Projectile.cs b/Assets/Scripts/Skills/Effectors/Projectile.cs
index bc0ef54..e27893b 100644
--- a/Assets/Scripts/Skills/Effectors/Projectile.cs
+++ b/Assets/Scripts/Skills/Effectors/Projectile.cs
@@ -43,26 +43,54 @@ namespace EerieVillage.Skills.Effectors
 
         protected virtual void OnTriggerEnter2D(Collider2D other)
         {
-            if (_hitTargets.Contains(other)) return;
+            // BT12-Dev 진단 (2026-05-09 PD A안) — 적 피격 X 근본 진단.
+            // 회수 의무: PD Console 결과 수령 + 근본 fix 적용 후 본 진단 Debug.Log 일괄 제거.
+            Debug.Log($"[Projectile][Enter] other={other.name} layer={other.gameObject.layer} t={Time.time:F2}");
+
+            if (_hitTargets.Contains(other))
+            {
+                Debug.Log($"[Projectile][Return] _hitTargets duplicate other={other.name}");
+                return;
+            }
 
             // PD 지시 2026-05-09 후속 방어 — 자기(Player) hit·자기 자신·hit 방어.
-            if (other.GetComponent<PlayerController>() != null) return;
+            if (other.GetComponent<PlayerController>() != null)
+            {
+                Debug.Log($"[Projectile][Return] PlayerController detected other={other.name}");
+                return;
+            }
 
             // Enemy 레이어 한정.
             // Phase 2-D fallback (2026-05-09): TagManager에 "Enemy" 레이어 미등재 시 LayerMask.NameToLayer 반환값 = -1.
             // 레이어 매칭 실패 시 EnemyController 컴포넌트 존재 여부로 대체 판정.
             int enemyLayer = LayerMask.NameToLayer("Enemy");
-            bool isEnemy = (enemyLayer != -1 && other.gameObject.layer == enemyLayer)
-                           || other.GetComponent<EnemyController>() != null;
-            if (!isEnemy) return;
+            bool hasEnemyController = other.GetComponent<EnemyController>() != null;
+            bool isEnemy = (enemyLayer != -1 && other.gameObject.layer == enemyLayer) || hasEnemyController;
+            Debug.Log($"[Projectile][LayerCheck] enemyLayer={enemyLayer} otherLayer={other.gameObject.layer} hasEnemyController={hasEnemyController} isEnemy={isEnemy}");
+
+            if (!isEnemy)
+            {
+                Debug.Log($"[Projectile][Return] not Enemy other={other.name}");
+                return;
+            }
 
             var health = other.GetComponent<Health>();
-            if (health == null || !health.IsAlive) return;
+            if (health == null)
+            {
+                Debug.Log($"[Projectile][Return] Health component missing other={other.name}");
+                return;
+            }
+            if (!health.IsAlive)
+            {
+                Debug.Log($"[Projectile][Return] Health not alive other={other.name} hp={health.CurrentHP}");
+                return;
+            }
 
             _hitTargets.Add(other);
 
             // 유효 대미지 산출 (balance/01 v0.2 §3 공식 — ActiveSkillRuntime.CalculateEffectiveDamage())
             int damage = _runtime.CalculateEffectiveDamage();
+            Debug.Log($"[Projectile][Hit] other={other.name} damage={damage}");
 
             // 피해 적용
             health.Decrement(damage);