render: extract static M2 batch materializer

docs/modules/world-renderer.md

@@ -54,6 +54,8 @@ flowchart LR
     M2Transform --> Loader
     Loader --> M2Batch[M2BuildBatchPlanner]
     M2Batch --> Loader
+    Loader --> M2Static[M2StaticBatchMaterializer]
+    M2Static --> Scene
     Loader --> WmoPlacement[WmoPlacementResolver]
     WmoPlacement --> Loader
     Loader --> WmoRegistry[WmoPlacementRegistry]
@@ -132,6 +134,7 @@ from externally reading/writing loader-private queue, task, cache and tile-state
 | `M2PlacementTransformResolver.resolve_basis/resolve_origin_offset` | Internal pure M2 service | Resolves regular and calibrated model-specific ADT placement transforms | Worker/main thread; stateless | Unknown paths use regular basis and zero offset |
 | `M2PlacementGrouper.group_placements` | Internal pure M2 service | Validates and groups ordered tile-local placement transforms by normalized path | Worker/main thread; stateless | Invalid variants/name IDs/empty paths are skipped |
 | `M2BuildBatchPlanner.plan_batch` | Internal pure M2 service | Selects static/animated batch count and next group cursor | Main/any thread; stateless | Non-positive selected limit clamps to one; empty range completes |
+| `M2StaticBatchMaterializer.materialize_batch` | Internal M2 scene-materialization service | Builds and attaches one prepared-Mesh MultiMesh transform slice | Renderer main thread; stateless after each call | Invalid/empty input returns null; bounds are caller precondition |
 | `M2RuntimeMeshRebuildClassifier` | Internal memoized M2 service | Detects billboard/UV-rotation metadata requiring stale cached-mesh rebuild | Renderer main thread; cached until reset | Invalid variants/indices skipped; first path decision wins |
 | `M2AnimationLoadPipelineState` | Internal M2 async-state service | Owns animated scene pending request records and terminal finalize FIFO | Renderer main thread; map/session | Empty/duplicate/unknown transitions rejected |
 | `M2AnimatedSceneFinalizer` | Internal M2 scene-finalization service | Instantiates candidates, repairs materials and requires AnimationPlayer descendants | Renderer main thread; stateless after each call | Invalid/rejected detached roots are freed |
@@ -179,6 +182,7 @@ loader configuration remains transitional composition data, not a caller API.
 | Internal transform | Rotation/path/scale | Loader or grouper / `M2PlacementTransformResolver` | Group/placeholder/instance transforms | Value-only Basis/Vector3 | One placement |
 | Internal grouping | Tile origin, M2 names and placements | Loader / `M2PlacementGrouper` | Loader worker result/build job | Fresh Dictionary/Transform3D arrays | One grouping task |
 | Internal batch plan | Transform count/offset, path kind and limits | Loader / `M2BuildBatchPlanner` | Loader materialization/cursor adapter | Fresh scalar Dictionary | One build operation |
+| Internal static M2 materialization | Parent, prepared Mesh, ordered transform slice and render settings | Loader / `M2StaticBatchMaterializer` | Attached MultiMeshInstance3D | Parent owns node/MultiMesh; exact Mesh reference retained | One main-thread build batch |
 | Internal WMO placement | Path, MODF placement, tile/index | Loader / `WmoPlacementResolver` | WMO caches, registry and three instance adapters | Value-only String/Transform3D | Lookup/placement lifetime |
 | Internal WMO ownership | Resolved placement key and tile/global reference key | Loader / `WmoPlacementRegistry` | Loader create/retain/final-free decisions | Registry-owned String sets; detached diagnostics | Map session or final release |
 | Internal WMO build step | Mesh/MultiMesh counts and job cursors | Loader / `WmoRenderBuildStepPlanner` | Loader materialization/cursor adapter | Fresh scalar Dictionary | One group operation |
@@ -239,7 +243,8 @@ flowchart TD
     M2Registry --> M2Grouper[M2PlacementGrouper]
     M2Transform[M2PlacementTransformResolver] --> M2Grouper
     M2Grouper --> M2Batch[M2BuildBatchPlanner]
-    M2Batch --> M2
+    M2Batch --> M2Static[M2StaticBatchMaterializer]
+    M2Static --> M2
     R --> WmoPlacement[WmoPlacementResolver]
     WmoPlacement --> WmoRegistry[WmoPlacementRegistry]
     WmoRegistry --> WmoBuildQueue[WmoRenderBuildQueue]
@@ -364,8 +369,10 @@ sequenceDiagram
   transforms and every build/render side effect remain loader-owned.
 - `M2PlacementGrouper` is stateless and owns only call-local grouped transforms.
   The loader retains tasks, mutex/result queues, stale checks and build state.
-- `M2BuildBatchPlanner` is stateless and owns only call-local scalar plans. The
-  loader retains queue/resource transitions, cursor adoption and materialization.
+- `M2BuildBatchPlanner` is stateless and owns only call-local scalar plans.
+  `M2StaticBatchMaterializer` owns static MultiMesh construction/attachment;
+  the loader retains queue/resource transitions, cursor adoption, animated/static
+  dispatch, budgets and Editor ownership.
 - `WmoPlacementResolver` is stateless and owns only call-local cache-key,
   identity and transform values. `WmoPlacementRegistry` owns only placement-key
   reference sets. `WmoRenderBuildStepPlanner` owns only a call-local operation
@@ -542,6 +549,7 @@ Exact exported settings and cache versions remain documented in [`../../RENDER.m
 |---|---|---|---|
 | ADT streaming/terrain | Partial | M00 checkpoints and current scenes | Fidelity/performance gaps remain |
 | Static M2 placement | Partial | MultiMesh/dedupe probes | Full materials/animation/effects |
+| M2 static batch materializer | Implemented extraction | Synthetic node/Mesh/render/source/timing contract | Asset-backed traversal/visual/GPU p95/p99 pending |
 | M2 unique placement registry | Implemented extraction | Scene-free ownership/lifecycle/timing contract and historical `uid:11785` smoke | Group/build/tasks/finalization and asset-backed p95/p99 remain pending |
 | M2 placement transform resolver | Implemented extraction | Scene-free formula/source/timing contract across three consumers | Asset-backed visual recheck and general placement parity pending |
 | M2 placement grouper | Implemented extraction | Scene-free validation/order/transform/source/timing contract | Worker/build state, spatial cells and asset-backed p95/p99 remain pending |
@@ -615,6 +623,7 @@ Exact exported settings and cache versions remain documented in [`../../RENDER.m
 | `src/render/m2/m2_animated_scene_finalizer.gd` | Animated scene candidate ownership, material repair and player validation |
 | `src/render/m2/m2_animation_playback_controller.gd` | Per-instance phase, selection, native copy/start and imported playback |
 | `src/render/m2/m2_animated_instance_materializer.gd` | Animated duplicate/render/playback startup and non-empty batch attachment |
+| `src/render/m2/m2_static_batch_materializer.gd` | Static MultiMesh construction, render setup and attachment |
 | `src/render/m2/m2_mesh_load_pipeline_state.gd` | Static M2 pending Resource paths, terminal statuses and finalize FIFO |
 | `src/render/m2/m2_mesh_resource_cache_state.gd` | Prepared static M2 Mesh references and final-shutdown release |
 | `src/render/m2/m2_mesh_resource_extractor.gd` | First-Mesh selection and temporary PackedScene instance lifetime |
@@ -640,6 +649,7 @@ Exact exported settings and cache versions remain documented in [`../../RENDER.m
 | `src/tools/verify_m2_animated_scene_finalizer.gd` | Animated M2 candidate/material/player/lifetime/boundary/timing regression |
 | `src/tools/verify_m2_animation_playback_controller.gd` | Animated M2 phase/selection/playback/native/boundary/timing regression |
 | `src/tools/verify_m2_animated_instance_materializer.gd` | Animated M2 order/render/playback/attachment/boundary/timing regression |
+| `src/tools/verify_m2_static_batch_materializer.gd` | Static M2 node/Mesh/render/attachment/boundary/timing regression |
 | `src/tools/verify_m2_mesh_load_pipeline_state.gd` | Static M2 request/terminal/FIFO/boundary/timing regression |
 | `src/tools/verify_m2_mesh_resource_cache_state.gd` | Static M2 Mesh cache ownership/lifetime/boundary/timing regression |
 | `src/tools/verify_m2_mesh_resource_extractor.gd` | M2 direct/PackedScene/subtree order/lifetime/boundary/timing regression |