EB-1: machines can die - structures get HP, Husks raze them, wounded base persists

Structures (Turret/Wall/Pylon) reuse the combat spine: authoring bakes Health(GhostField)+DamageEvent buffer+a Destructible tag (no HitRadius -> no friendly projectile fire; no EffectiveCharacterStats -> clamp-to-0). HealthApplyDamageSystem destroys a Destructible at 0 (occupancy auto-frees). EnemyAISystem fortress-targets the weighted-nearest of players+structures via the shared EnemyAIMath.PickWeightedNearest (StructureAggroWeight TuningConfig knob, <1 prefers structures, squared factor; snapshot above the early-return so an undefended base is razed). Persistence v3: per-structure HP threaded through 5 sites (SaveData/PendingStructure/scan-guarded/BaseRestore same-ECB born-correct/WorldLauncher via SaveApply.ToPending); SaveService floor-gate [2,3] loads old saves. Loss feedback: proximity-gated StructureFeedbackSystem; CombatFeedbackSystem suppressed for structures. Pre-code review caught the DamageEvent-buffer crash blocker + 8 majors; post-code review clean. See DR-032.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Assets/_Project/Scripts/Simulation/Combat/Destructible.cs

@@ -0,0 +1,14 @@
+using Unity.Entities;
+
+namespace ProjectM.Simulation
+{
+    /// <summary>
+    /// EB-1 — opt-in marker for an entity that <see cref="ProjectM.Server.HealthApplyDamageSystem"/> DESTROYS when
+    /// its <see cref="Health"/> hits 0 (alongside <c>TrainingDummyTag</c>/<c>EnemyTag</c>). Baked ONLY on the
+    /// player-built structure ghosts (Turret/Wall/Pylon) so "machines can die". DELIBERATELY a distinct tag rather
+    /// than gating on bare <see cref="PlacedStructure"/>: that identity is SHARED by the reserved M7 automation
+    /// machines (Harvester/Fabricator/Conveyor) whose teardown would silently drop in-flight conveyor cargo — the
+    /// tag lets each destructible opt in explicitly (zero-size, ghost-hash-neutral). See [[DR-031]] follow-on EB-1.
+    /// </summary>
+    public struct Destructible : IComponentData { }
+}

Assets/_Project/Scripts/Simulation/Combat/Destructible.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: a0efc019048795541ba13795d724f331

Assets/_Project/Scripts/Simulation/Combat/EnemyAIMath.cs

@@ -1,3 +1,4 @@
+using Unity.Collections;
 using Unity.Mathematics;
 
 namespace ProjectM.Simulation
@@ -68,5 +69,31 @@ namespace ProjectM.Simulation
             math.sincos(angle, out float s, out float c);
             return center + new float3(c * radius, 0f, s * radius);
         }
+        /// <summary>
+        /// EB-1 fortress aggro: pick a Husk's target as the weighted-nearest of the living players (weight 1) and
+        /// the live structures (a SQUARED <paramref name="structureWeight"/> applied to structure distance, so &lt;1
+        /// makes structures preferred while a sufficiently-closer player 'in the way' still wins). Planar XZ,
+        /// deterministic (no RNG/wall-clock). Sets <paramref name="index"/> = -1 when there are no targets. Pure so
+        /// both the Grunt and Charger passes select IDENTICALLY and it is EditMode-unit-testable.
+        /// </summary>
+        public static void PickWeightedNearest(float3 from, NativeList<float3> playerPositions,
+            NativeList<float3> structurePositions, float structureWeight, out bool isStructure, out int index)
+        {
+            isStructure = false;
+            index = -1;
+            float bestSq = float.MaxValue;
+            for (int i = 0; i < playerPositions.Length; i++)
+            {
+                float sq = math.lengthsq(playerPositions[i].xz - from.xz);
+                if (sq < bestSq) { bestSq = sq; index = i; isStructure = false; }
+            }
+            float w = math.max(0f, structureWeight);
+            float wsq = w * w; // applied to SQUARED distance so the weight scales true distance
+            for (int i = 0; i < structurePositions.Length; i++)
+            {
+                float sq = math.lengthsq(structurePositions[i].xz - from.xz) * wsq;
+                if (sq < bestSq) { bestSq = sq; index = i; isStructure = true; }
+            }
+        }
     }
 }