Hazard: destructible cover — carve-able rocks that genuinely block until broken

Phase 1.5 long-term #8, the LAST 1.5 item (design review wf_e14dd739-069:
both HIGHs + the distinct MEDs verified before the session limit ate the
duplicate verifiers; unverified leftovers reasoned-closed in the spec).

Cover = a BlightClutter ghost (Variant 4) with a baked Environment-layer
BoxCollider: the runtime ghost's collider joins BuildPhysicsWorld ->
blocks the player CC and the enemy sweep while alive, and the gap opens
the instant the entity dies. Both hit paths already break it (the
clutter chassis); 8 hits to carve.

Review folds:
- HIGH: the 07-07 anti-stuck nudge would phase enemies THROUGH cover
  after ~1.5s (it exists to prevent room soft-locks). The nudge is now
  COVER-AWARE: a SphereCast identifies the blocker; a live BlightClutter
  ghost suppresses the phase (no soft-lock possible - the blocker is
  destructible); static-geometry wedges still nudge.
- HIGH: yield==durability made tanky cover an economy faucet. Deposit
  is DECOUPLED from the decrement at both hit sites: ScrapPerHit=0 =
  breaks in Remaining hits, yields NOTHING; fractional POSITIVE yields
  still credit >=1 (the B1 immortal-sink test pinned this - zero means
  zero, positive floors to 1).
- MEDs: HitRadius 1.2 (visual core, not a shot-eating disc), NO cover
  in Boss rooms (no boss depenetration backstop), scatter keep-out >=7u
  from the room origin (player landing + portal), Variant=4 explicit
  (the clutter block's explosive reroll cannot leak).
- Old static layer removed: 8 WorldColliders_RoomCover colliders
  (subscene) + the RoomCover_Visuals root (Game.unity).

Verified live: 3 cover ghosts spawned with SOLID baked colliders;
BLOCK - NudgeUntilTick stayed 0 across 3.5s of forced zero-progress
(old code arms at 1.5s); DEPENETRATE - an enemy shoved inside a live
rock exited to 1.7u (backstop holds against ghost colliders); CARVE -
the rock died to the real sweep and the spot probed OPEN. 470/470
EditMode; console clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Assets/_Project/Scripts/Simulation/Economy/CoverFieldSpawner.cs

@@ -0,0 +1,22 @@
+using Unity.Entities;
+
+namespace ProjectM.Simulation
+{
+    /// <summary>
+    /// Baked singleton holding the DESTRUCTIBLE COVER ghost prefab (Exploding_Barrels sibling —
+    /// Cover_Rock_Build: a BlightClutter carrier with ScrapPerHit=0, Variant=4, and a baked
+    /// Environment-layer collider that blocks the player CC and the enemy sweep while alive).
+    /// RoomFieldSystem scatters <see cref="Count"/> cover rocks per room epoch — EXCEPT Boss rooms
+    /// (the boss has no depenetration backstop; review wf_e14dd739-069) — with a keep-out ring
+    /// around the room origin (player landing + portal). OPTIONAL: absent singleton = no cover.
+    /// Mirrors <see cref="ClutterFieldSpawner"/>; carries no transform.
+    /// </summary>
+    public struct CoverFieldSpawner : IComponentData
+    {
+        /// <summary>Baked cover-rock ghost prefab to instantiate.</summary>
+        public Entity Prefab;
+
+        /// <summary>Cover rocks per room (Boss rooms get none).</summary>
+        public int Count;
+    }
+}

Assets/_Project/Scripts/Simulation/Economy/CoverFieldSpawner.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: 0331196c0b301674189f1c1779f108da

Assets/_Project/Scripts/Simulation/Player/MeleeComboSystem.cs

@@ -270,6 +270,10 @@ namespace ProjectM.Simulation
                             continue;
 
                         int amount = math.max(1, (int)harvPerHit[i]);
+                        // DECOUPLED deposit (cover review): cover has ScrapPerHit=0 — breaks in Remaining hits,
+                        // yields nothing. Nodes/clutter (PerHit >= 1) keep deposit == decrement as before.
+                        // zero means ZERO (cover); any POSITIVE yield still credits >= 1 (the fractional-yield guard).
+                        int deposit = harvPerHit[i] > 0f ? amount : 0;
                         byte yieldId = harvYieldId[i];
                         // Route by region: Base nodes credit the shared ledger DIRECTLY (the build pool); an
                         // expedition / un-tagged target goes to the swinging player's PERSONAL inventory (spill to
@@ -278,10 +282,13 @@ namespace ProjectM.Simulation
                         Entity meleeHarvester = Entity.Null;
                         if (meleePlayerByConn.TryGetValue(hc.OwnerId, out var meleePlayer))
                             meleeHarvester = meleePlayer;
-                        bool deposited = HarvestMath.DepositYield(yieldId, amount, harvToLedger[i], meleeHarvester,
-                            m_InvLookup, ledger, haveLedger, haveDb, itemDb);
-                        if (!deposited)
-                            continue;
+                        if (deposit > 0)
+                        {
+                            bool deposited = HarvestMath.DepositYield(yieldId, deposit, harvToLedger[i], meleeHarvester,
+                                m_InvLookup, ledger, haveLedger, haveDb, itemDb);
+                            if (!deposited)
+                                continue; // never consume a YIELDING target for zero credit
+                        }
 
                         int rem = harvRemaining[i] - amount;
                         harvRemaining[i] = rem;