docs(physics): close Slice I evidence and roadmap

Record the accepted flat-authoritative collision cutover, production parsed-graph removal, exact rollbacks, zero-residency connected gates, and RDP measurement boundary. Reconcile architecture, milestones, roadmap, issue ledger, agent instructions, and the active Slice J handoff.

Validated by the existing zero-warning Release build, 8,413 passing Release tests with five pre-existing skips, 201 focused closeout tests, and both exact-binary connected routes.

Co-authored-by: Codex <codex@openai.com>

docs/architecture/acdream-architecture.md

@@ -175,7 +175,7 @@ src/
       TransitionTypes.cs      -> SpherePath / CollisionInfo / transition helpers (active in L.2)
       FlatCollisionAssets.cs  -> immutable array/index collision schema (Slice I2)
       FlatCollisionAssetBuilder.cs -> deterministic DAT graph preparation (Slice I2/I3)
-      PhysicsDataCache.cs     -> GfxObj / Setup / CellStruct collision data (done, active)
+      PhysicsDataCache.cs     -> flat prepared GfxObj / Setup / CellStruct / EnvCell collision owner
       ShadowObjectRegistry.cs -> broadphase for nearby physics objects (active)
       PhysicsEngine.cs        -> ResolveWithTransition active player path
       ProjectilePhysicsStepper.cs -> pure retail projectile integration + sweep
@@ -204,7 +204,7 @@ src/
     Messages/                 -> done (CreateObject, MoveToState, etc.)
 
   AcDream.Runtime/           presentation-independent client kernel boundary
-    RuntimeAssemblyMarker.cs  -> J0 dependency boundary; owner moves start after I6/I7
+    RuntimeAssemblyMarker.cs  -> J0 dependency boundary; J1 contracts active
     -> may reference Core, Core.Net, Content, and Plugin.Abstractions only
     -> must never reference App, UI, Silk.NET, OpenAL, Arch, or ImGui
   
@@ -406,7 +406,10 @@ What exists and is active:
 - `TransitionTypes` carries `SpherePath`, `CollisionInfo`, `ObjectInfo`,
   transition validation, step-up/down, contact-plane handling, and partial
   slide behavior.
-- `PhysicsDataCache` loads GfxObj, Setup, and CellStruct physics data from DATs.
+- `PhysicsDataCache` owns immutable flat GfxObj, Setup, CellStruct, and EnvCell
+  collision assets loaded from the validated prepared package. Production
+  retains no parsed DAT collision graph; graph construction is restricted to
+  bake/equivalence tools and explicit test oracles.
 - `ShadowObjectRegistry` gives movement a broadphase over nearby objects and
   buildings.
 - `TerrainSurface` uses triangle-aware terrain contact; older "bilinear terrain

docs/architecture/worldbuilder-inventory.md

@@ -140,8 +140,8 @@ strict little-endian codec and `IPreparedCollisionSource`.
 `PakPreparedAssetSource` implements the render and collision interfaces over
 one mmap; it does not create a second DAT reader or mapping. CellStruct
 payloads alias only after exact serialized-byte comparison, while each
-EnvCell topology remains independently keyed. Production traversal is still
-the parsed graph oracle until Slice I6. Full-catalog evidence:
+EnvCell topology remains independently keyed. Production traversal remained
+on the parsed graph oracle until the later Slice-I cutover. Full-catalog evidence:
 `docs/research/2026-07-25-slice-i3-prepared-collision-package.md`.
 
 **Slice I5 dual-publication seam (2026-07-25).** Near-tier
@@ -155,6 +155,19 @@ fault. This is still one `DatCollection` and one prepared-package mmap, not a
 second reader or a WorldBuilder runtime dependency. Evidence:
 `docs/research/2026-07-25-slice-i5-dual-collision-shadow.md`.
 
+**Slice I6/I7 flat-authoritative closeout (2026-07-25).** Production
+`PhysicsDataCache` now publishes only immutable flat GfxObj, Setup,
+CellStruct, and EnvCell-topology records from the validated package. Stable
+world state strips temporary `PhysicsDatBundle` source material, and near
+landblock builds discard raw Environment/GfxObj collision graphs once the
+flat closure exists. Parsed graph constructors remain explicit
+test/bake/equivalence oracles only; gameplay has no graph fallback or referee.
+Both exact-binary connected routes report `0/0/0` retained parsed collision
+graphs at every stable checkpoint while flat residency remains populated.
+This remains one `DatCollection`, one preparation algorithm, and one package
+mmap. Evidence:
+`docs/research/2026-07-25-slice-i7-closeout.md`.
+
 **Retail VFX hook compatibility seam (2026-07-14).** Chorizite.DatReaderWriter
 2.1.7 models `CreateBlockingParticleHook` as the common hook header only, while
 retail inherits the complete `CreateParticleHook` payload. The narrow readers in