Docs: destructible-cover Build Spec + session log Part K — PHASE 1.5 COMPLETE

CLAUDE.md: the enemy anti-stuck nudge is now cover-aware (budget 38.5 KB).

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

Docs/Vault/03_Design/Destructible_Cover_Build_Spec.md

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+---
+title: Destructible_Cover_Build_Spec
+type: note
+permalink: gamevault/03-design/destructible-cover-build-spec
+---
+
+# Destructible Cover — Build Spec (Phase 1.5 long-term #8, review-hardened, SHIPPED `bbf418e77`)
+
+Review: `wf_e14dd739-069` (3 lenses, 28 agents). The session limit killed 18 verifiers mid-run, but the 7
+completed verifications covered every DISTINCT load-bearing finding (both HIGHs + the boss/scatter/copy-paste/
+HitRadius/spawn-window MEDs); the dead verifiers were lens-duplicates of the same issues. **Deliberate call:
+folded without a third verify pass**, with the unverified leftovers reasoned-closed below — recorded per
+[[ask-before-deferring-during-implementation]].
+
+## Core architecture: cover IS clutter with a collider
+
+`CoverRock.prefab` = a `BlightClutter` ghost (Variant **4**) whose root carries a baked **Environment-layer
+BoxCollider**: the runtime-spawned ghost's collider joins `BuildPhysicsWorld` every tick → blocks the player
+CC AND the enemy sweep (both filter on the env mask) while alive, and the gap opens the instant the entity
+dies. Both hit paths break it for free (the clutter chassis); chip feedback/teardown/relevancy inherited.
+Values: `Remaining=8` (8 hits to carve), `ScrapPerHit=0`, `HitRadius=1.2`, Model = `SM_Env_Rocks_Spikey_03`
+@1.7 (the old cover visual; Read/Write already enabled).
+
+## The two HIGH folds
+
+1. **The 07-07 anti-stuck nudge deliberately phases enemies through cover rocks** (it exists to prevent room
+   soft-locks) — "cover blocks enemies" contradicted the shipped backstop. Fold: the nudge is **cover-aware**
+   (EnemyAISystem, the arm site): a 1.8 u SphereCast toward the target identifies the blocker; if it carries
+   `BlightClutter` (a LIVE, destructible ghost — no soft-lock possible) the phase is SUPPRESSED and the stuck
+   counter stays primed; static-geometry wedges nudge exactly as before.
+2. **Yield==durability coupling** made tanky cover a 64-scrap/room faucet. Fold: deposit DECOUPLED from the
+   decrement at BOTH hit sites — `deposit = perHit > 0 ? max(1,(int)perHit) : 0` — zero means ZERO (cover),
+   any positive still credits ≥1 (the B1 immortal-sink regression test caught the first cut truncating 0.5→0;
+   the dual contract is now: fractional-positive floors to 1, exact-zero deposits nothing).
+
+## Confirmed-MED folds
+
+- `HitRadius=1.2` (visual core): the collider footprint would have made each rock a ~5 u shot-eating disc
+  (ResourceHarvest consumes any surviving projectile whose segment grazes HitRadius).
+- **No cover in Boss rooms**: the boss moves only via SweptMove — NO depenetration backstop exists for it
+  (`EnemyAISystem`'s pass excludes BossState with a comment wrongly claiming BossAISystem owns it).
+- Scatter keep-out ≥7 u from the room origin (player landing at origin+1.5·idx, portal at z−5), bounded
+  8-attempt resample, piece dropped on failure. Count=3/room (`CoverFieldSpawner`, optional singleton).
+- `Variant=4` set on the prefab and NEVER rerolled (the clutter block's 25% explosive reroll is a copy-paste
+  trap — the cover spawn block instantiates the prefab proto untouched).
+- Old static layer REMOVED: 8 `WorldColliders_RoomCover` subscene colliders + the `RoomCover_Visuals` root in
+  Game.unity (double-collision + double-visual otherwise). ColliderFitTools' FitCover section is vestigial
+  (empty group → KEEP logs).
+
+## Reasoned-closed (verifiers lost to the session limit; dispositions)
+
+- *CC misprediction window on runtime-spawned blockers*: rocks spawn at room entry ≥7 u from the landing
+  point; the ghost replicates long before a player can cross 7 u — no practical mispredict window.
+- *Depenetrate vertical-normal on hull tops*: unchanged behavior class vs the old static hulls; the fallback
+  chain (nudge) still exists for non-cover geometry.
+- *Melee cone tests target CENTER*: rock center reachable at HitRadius 1.2 + cone range 2.6 — chippable
+  point-blank.
+- *NodeFeedback shrink keys on Remaining*: cover shrinking as it is chipped reads as crumbling — kept.
+- *Projectiles ignore colliders* (confirmed structurally): v1 cover blocks MOVEMENT, not shots — both sides'
+  projectiles fly over the waist-high rocks. True shot-blocking = a follow-up (cover in both projectile
+  sweeps). Enemy-hits-win ordering is deterministic: ProjectileDamage (predicted group, immediate playback)
+  runs before ResourceHarvest (plain group) — a projectile consumed on an enemy is gone before the harvest
+  sweep can double-destroy it.
+- *Charger smashes through cover*: deliberate follow-up (contact damage from lunging chargers to cover).
+
+## Live validation (all passed, 2026-07-10)
+
+3 cover ghosts spawned (Variant 4, Remaining 8) with SOLID baked colliders in the CollisionWorld ·
+**BLOCK**: `NudgeUntilTick` stayed 0 across 3.5 s of forced zero-progress (the old code arms at 1.5 s) ·
+**DEPENETRATE**: an enemy shoved inside a live rock exited to 1.7 u · **CARVE**: the rock died to the real
+projectile sweep and the spot probed OPEN (not solid) · 470/470 EditMode · console clean.