diff --git a/Assets/_Project/Tests/EditMode/BossAISystemTests.cs b/Assets/_Project/Tests/EditMode/BossAISystemTests.cs
new file mode 100644
index 000000000..7677c1dfe
--- /dev/null
+++ b/Assets/_Project/Tests/EditMode/BossAISystemTests.cs
@@ -0,0 +1,159 @@
+using NUnit.Framework;
+using ProjectM.Server;
+using ProjectM.Simulation;
+using Unity.Entities;
+using Unity.Mathematics;
+using Unity.Transforms;
+
+namespace ProjectM.Tests
+{
+    /// <summary>
+    /// Plain-Entities EditMode coverage for the server-only BossAISystem (the sole boss mover/attacker, previously
+    /// Play-only). Exercises phase gating, expedition-only targeting, the telegraphed radial-slam AoE + its radius
+    /// boundary, the B4 lunge-vs-slam windup disambiguation (a naive shared-windup reuse would slam on a lunge
+    /// elapse), and knockback immunity. Values are pinned to Tuning.Boss* so the tests track tuning, not literals.
+    /// No PhysicsWorldSingleton is created -> sweep=false -> the boss moves/lands unswept (headless-safe).
+    /// </summary>
+    public class BossAISystemTests
+    {
+        static Entity MakeBoss(EntityManager em, float3 pos, float cur, float max,
+            byte pending = 0, uint windup = 0, uint slamReady = 0, uint lungeReady = 0, uint knockUntil = 0)
+        {
+            var e = em.CreateEntity(typeof(EnemyTag), typeof(BossState), typeof(LocalTransform), typeof(EnemyStats),
+                typeof(Health), typeof(AttackWindup), typeof(KnockbackState), typeof(LungeState));
+            em.SetComponentData(e, LocalTransform.FromPosition(pos));
+            em.SetComponentData(e, new EnemyStats { MoveSpeed = 3f, AttackRange = 2f, AttackDamage = 10f, AttackCooldownTicks = 30 });
+            em.SetComponentData(e, new Health { Current = cur, Max = max });
+            em.SetComponentData(e, new BossState { Phase = 1, PendingAttack = pending, SlamReadyTick = slamReady, LungeReadyTick = lungeReady });
+            em.SetComponentData(e, new AttackWindup { WindUpUntilTick = windup });
+            em.SetComponentData(e, new KnockbackState { UntilTick = knockUntil });
+            return e;
+        }
+
+        static Entity MakePlayer(EntityManager em, float3 pos, byte region = RegionId.Expedition, float hp = 100f)
+        {
+            var e = em.CreateEntity(typeof(PlayerTag), typeof(RegionTag), typeof(LocalTransform), typeof(Health), typeof(DamageEvent));
+            em.SetComponentData(e, new RegionTag { Region = region });
+            em.SetComponentData(e, LocalTransform.FromPosition(pos));
+            em.SetComponentData(e, new Health { Current = hp, Max = hp });
+            return e;
+        }
+
+        [Test]
+        public void Phase_One_When_Above_Half_HP()
+        {
+            var (world, group) = TestWorld.Make<BossAISystem>("Boss_P1", tick: 200, server: true);
+            using (world)
+            {
+                var em = world.EntityManager;
+                var boss = MakeBoss(em, float3.zero, cur: 60f, max: 100f);
+                MakePlayer(em, new float3(3f, 0f, 0f));
+                group.Update();
+                Assert.AreEqual((byte)1, em.GetComponentData<BossState>(boss).Phase, "Above the phase-2 fraction -> phase 1.");
+            }
+        }
+
+        [Test]
+        public void Phase_Two_At_Or_Below_Half_HP()
+        {
+            var (world, group) = TestWorld.Make<BossAISystem>("Boss_P2", tick: 200, server: true);
+            using (world)
+            {
+                var em = world.EntityManager;
+                float cur = 100f * Tuning.BossPhase2HealthFraction; // exactly the boundary
+                var boss = MakeBoss(em, float3.zero, cur: cur, max: 100f);
+                MakePlayer(em, new float3(3f, 0f, 0f));
+                group.Update();
+                Assert.AreEqual((byte)2, em.GetComponentData<BossState>(boss).Phase, "At/below the fraction -> phase 2.");
+            }
+        }
+
+        [Test]
+        public void No_Living_Expedition_Target_Leaves_Boss_Idle()
+        {
+            var (world, group) = TestWorld.Make<BossAISystem>("Boss_NoTgt", tick: 200, server: true);
+            using (world)
+            {
+                var em = world.EntityManager;
+                var boss = MakeBoss(em, float3.zero, cur: 100f, max: 100f);
+                MakePlayer(em, new float3(3f, 0f, 0f), region: RegionId.Base);      // wrong region
+                MakePlayer(em, new float3(4f, 0f, 0f), region: RegionId.Expedition, hp: 0f); // dead
+
+                group.Update();
+
+                Assert.AreEqual(float3.zero, em.GetComponentData<LocalTransform>(boss).Position, "No valid target -> the boss does not move.");
+                Assert.AreEqual(0u, em.GetComponentData<AttackWindup>(boss).WindUpUntilTick, "No target -> no telegraph.");
+            }
+        }
+
+        [Test]
+        public void Slam_Lands_Radial_AoE_On_Windup_Elapse()
+        {
+            var (world, group) = TestWorld.Make<BossAISystem>("Boss_Slam", tick: 200, server: true);
+            using (world)
+            {
+                var em = world.EntityManager;
+                var boss = MakeBoss(em, float3.zero, cur: 100f, max: 100f, pending: 0, windup: 100); // 100 <= 200 -> elapsed
+                var player = MakePlayer(em, new float3(1f, 0f, 0f)); // inside slam radius
+
+                group.Update();
+
+                var dmg = em.GetBuffer<DamageEvent>(player);
+                Assert.AreEqual(1, dmg.Length, "A player inside the slam radius takes one hit on landing.");
+                Assert.AreEqual(Tuning.BossSlamDamage, dmg[0].Amount, 1e-3f);
+                Assert.AreEqual(-1, dmg[0].SourceNetworkId, "Slam damage is sourced from the boss/environment (-1).");
+                Assert.AreEqual(0u, em.GetComponentData<AttackWindup>(boss).WindUpUntilTick, "Windup cleared after landing.");
+            }
+        }
+
+        [Test]
+        public void Slam_Misses_A_Player_Outside_The_Radius()
+        {
+            var (world, group) = TestWorld.Make<BossAISystem>("Boss_SlamMiss", tick: 200, server: true);
+            using (world)
+            {
+                var em = world.EntityManager;
+                MakeBoss(em, float3.zero, cur: 100f, max: 100f, pending: 0, windup: 100);
+                var player = MakePlayer(em, new float3(Tuning.BossSlamRadius + 1f, 0f, 0f)); // just outside
+
+                group.Update();
+
+                Assert.AreEqual(0, em.GetBuffer<DamageEvent>(player).Length, "Outside the slam radius takes no hit.");
+            }
+        }
+
+        [Test]
+        public void Lunge_Windup_Elapse_Commits_Travel_And_Does_Not_Slam()
+        {
+            var (world, group) = TestWorld.Make<BossAISystem>("Boss_Lunge", tick: 200, server: true);
+            using (world)
+            {
+                var em = world.EntityManager;
+                var boss = MakeBoss(em, float3.zero, cur: 100f, max: 100f, pending: 1, windup: 100); // PendingAttack=1 => lunge
+                var player = MakePlayer(em, new float3(1f, 0f, 0f)); // inside slam radius, but a LUNGE must not slam
+
+                group.Update();
+
+                Assert.AreEqual(0, em.GetBuffer<DamageEvent>(player).Length, "A lunge elapse must NOT deal slam damage (B4 disambiguation).");
+                Assert.AreEqual(Tuning.BossLungeSpeed, em.GetComponentData<LungeState>(boss).Speed, 1e-3f, "Lunge travel committed.");
+                Assert.AreEqual(0u, em.GetComponentData<AttackWindup>(boss).WindUpUntilTick, "Windup cleared on lunge commit.");
+            }
+        }
+
+        [Test]
+        public void Knockback_Residual_Is_Zeroed_Boss_Is_Immune()
+        {
+            var (world, group) = TestWorld.Make<BossAISystem>("Boss_Knock", tick: 200, server: true);
+            using (world)
+            {
+                var em = world.EntityManager;
+                var boss = MakeBoss(em, float3.zero, cur: 100f, max: 100f, knockUntil: 999u);
+                MakePlayer(em, new float3(3f, 0f, 0f));
+
+                group.Update();
+
+                Assert.AreEqual(0u, em.GetComponentData<KnockbackState>(boss).UntilTick, "The boss is knockback-immune: residual is zeroed.");
+            }
+        }
+    }
+}
diff --git a/Assets/_Project/Tests/EditMode/BossAISystemTests.cs.meta b/Assets/_Project/Tests/EditMode/BossAISystemTests.cs.meta
new file mode 100644
index 000000000..c84c70e56
--- /dev/null
+++ b/Assets/_Project/Tests/EditMode/BossAISystemTests.cs.meta
@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: 407138571a76c6f4f821fcbde92327a5
\ No newline at end of file