refactor(M03): extract WMO placement registry

docs/modules/wmo-placement-resolver.md

@@ -19,7 +19,8 @@ live-prototype instance paths.
 ## Non-goals
 
 - Parse ADT/WDT or convert canonical WoW coordinates.
-- Own WMO registry references, tile state, jobs, queues or retries.
+- Own WMO registry references, tile state, jobs, queues or retries; reference
+  ownership belongs to `WmoPlacementRegistry`.
 - Load/validate cached scenes or lightweight render resources.
 - Create Nodes, Mesh/MultiMesh, materials or RIDs.
 - Implement portals, rooms, visibility, materials, doodads or WMO parity.
@@ -34,7 +35,7 @@ flowchart LR
     Resolver --> Identity[Registry unique key]
     Resolver --> Transform[World Transform3D]
     CacheKey --> Cache[Loader WMO caches/requests]
-    Identity --> Registry[Loader WMO registry]
+    Identity --> Registry[WmoPlacementRegistry]
     Transform --> RenderRoot[Lightweight render root]
     Transform --> Scene[Cached scene instance]
     Transform --> Live[Live prototype instance]
@@ -60,7 +61,7 @@ WorkerThreadPool, mutexes, files, gameplay, network and editor UI are forbidden.
 | Input | Raw placement Dictionary | WDT global or ADT MODF parser result | Identity/transform queries | Read-only shallow value | One call |
 | Input | Tile key and placement index | Loader build job | Synthetic identity fallback | Copied scalar/String | Registry entry lifetime |
 | Output | Normalized relative path | Resolver | Render/scene cache and load-request maps | New String value | Request/cache lookup |
-| Output | `uid:*` or `tile:*:*` key | Resolver | Loader WMO registry/ref arrays | New String value | Until unregister/reset |
+| Output | `uid:*` or `tile:*:*` key | Resolver | `WmoPlacementRegistry` and loader ref arrays | New String value | Until unregister/reset |
 | Output | World `Transform3D` | Resolver | Three WMO instance adapters | Value copy | Instance lifetime after assignment |
 
 The resolver retains no source Dictionary, output or engine resource.
@@ -91,7 +92,7 @@ and shutdown require no resolver operation.
 sequenceDiagram
     participant Loader as StreamingWorldLoader
     participant Resolver as WmoPlacementResolver
-    participant Registry as Loader WMO registry/cache
+    participant Registry as WmoPlacementRegistry
     participant Instance as Render/cached/live instance
     Loader->>Resolver: normalize_relative_path(path)
     Resolver-->>Loader: cache key
@@ -105,8 +106,9 @@ sequenceDiagram
 ## Ownership, threading and resources
 
 - The resolver owns only call-local scalar/value calculations.
-- The loader owns WMO registry entries/ref sets, cache/load-request state, build
-  jobs/queues, resource fallback and cancellation.
+- `WmoPlacementRegistry` owns placement-key reference sets. The loader owns its
+  key-to-Node map, cache/load-request state, jobs/queues, resource fallback and
+  cancellation.
 - The loader and builders own every Node/Mesh/MultiMesh/material/RID lifecycle.
 - Pure calls are thread-safe; current consumers execute on the main thread.
 
@@ -152,8 +154,8 @@ in the facade/loader diagnostic snapshot.
 
 ## Extension points
 
-- A later package may extract WMO registry ownership/ref release using these
-  stable keys.
+- `WmoPlacementRegistry` consumes these stable keys; later packages may extract
+  WMO build/resource state without changing the resolver.
 - Render-group build cursor and resource-selection state require separate
   lifecycle/cancellation contracts.
 
@@ -162,7 +164,8 @@ in the facade/loader diagnostic snapshot.
 | Capability | Status | Evidence | Gap/next step |
 |---|---|---|---|
 | Consistent WMO placement identity/transform | Implemented extraction | Contract/source/timing verifier | Asset-backed placement comparison pending |
-| WMO registry/build services | Remains in loader | Existing runtime regressions | Stateful extraction pending |
+| WMO placement registry | Implemented extraction | Ownership/source/timing verifier | Asset-backed cross-tile corpus pending |
+| WMO build services | Remains in loader | Existing runtime regressions | Stateful extraction pending |
 | Portals/rooms/material fidelity | Partial | M00 checkpoint/material evidence | Broader WMO implementation pending |
 
 ## Known gaps and risks
@@ -177,11 +180,13 @@ in the facade/loader diagnostic snapshot.
 | Path | Responsibility |
 |---|---|
 | `src/render/wmo/wmo_placement_resolver.gd` | Path, identity and transform rules |
-| `src/scenes/streaming/streaming_world_loader.gd` | Registry/cache/build/resource/Node ownership |
+| `src/render/wmo/wmo_placement_registry.gd` | Placement reference-set ownership |
+| `src/scenes/streaming/streaming_world_loader.gd` | Node map/cache/build/resource ownership |
 | `src/tools/verify_wmo_placement_resolver.gd` | Contract, source and timing regression |
 
 ## Related decisions and references
 
 - [`world-renderer.md`](world-renderer.md)
+- [`wmo-placement-registry.md`](wmo-placement-registry.md)
 - [`../../RENDER.md`](../../RENDER.md)
 - [`../../targets/roadmap/02-rendering-and-graphics.md`](../../targets/roadmap/02-rendering-and-graphics.md)