refactor(M03): extract M2 placement grouper

docs/modules/world-renderer.md

@@ -5,9 +5,9 @@
 | Field | Value |
 |---|---|
 | Status | Partial |
-| Target/work package | M00 baseline; `M01-RND-STREAMING-FOCUS-001`; `M01-QAR-SERVER-SPAWN-RENDERER-001`; M03 facade/planner/scheduler/internal-access/ground/environment/entity packages; M03 terrain packages; M03 M2 unique/transform packages |
+| Target/work package | M00 baseline; `M01-RND-STREAMING-FOCUS-001`; `M01-QAR-SERVER-SPAWN-RENDERER-001`; M03 facade/planner/scheduler/internal-access/ground/environment/entity packages; M03 terrain packages; M03 M2 unique/transform/grouping packages |
 | Owners | Renderer workstream / milestone integrator |
-| Last verified | Worktree `work/sindo-main-codex/m03-m2-placement-transform`, 2026-07-16 |
+| Last verified | Worktree `work/sindo-main-codex/m03-m2-placement-grouper`, 2026-07-16 |
 | Profiles/capabilities | `Performance`, `Balanced`, `High`, `Custom`; Blizzlike fidelity incomplete |
 
 ## Purpose
@@ -48,7 +48,9 @@ flowchart LR
     ChunkQueue --> Loader
     Loader --> M2Registry[M2UniquePlacementRegistry]
     M2Registry --> Loader
-    Loader --> M2Transform[M2PlacementTransformResolver]
+    Loader --> M2Grouper[M2PlacementGrouper]
+    M2Grouper --> M2Transform[M2PlacementTransformResolver]
+    M2Transform --> M2Grouper
     M2Transform --> Loader
     Native --> Parsed[Parsed tile/model data]
     Parsed --> Loader
@@ -118,6 +120,7 @@ from externally reading/writing loader-private queue, task, cache and tile-state
 | `TerrainChunkGeometryQueuePlanner.plan` | Internal pure terrain query | Produces chunk create/remove requests from current and desired state | Synchronous per queue rebuild | Invalid focus returns empty arrays |
 | `M2UniquePlacementRegistry.reserve/release/clear` | Internal M2 service | Owns positive cross-tile ADT placement-ID reservations | Renderer thread/map session | Invalid/unkeyed/non-owner inputs preserve documented fallback |
 | `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 |
 
 Публичным contract не считаются `StreamingWorldLoader` methods/properties,
 внутренние dictionaries, queues, job records и generated node names. Scene-owned
@@ -143,7 +146,8 @@ loader configuration remains transitional composition data, not a caller API.
 | Internal plan | Parsed chunks, typed focus and immutable chunk-LOD policy | Loader / `TerrainChunkLodPlanner` | Loader desired state | Fresh dictionary; no retained resources | One target refresh |
 | Internal plan | Current/desired chunk state and typed focus | Loader / `TerrainChunkGeometryQueuePlanner` | Loader chunk queues | Fresh request arrays; no retained resources | One queue rebuild |
 | Internal registry | Tile key and M2 placement unique IDs | Loader / `M2UniquePlacementRegistry` | Filtered grouping input and tile retry state | Registry-owned strings; fresh result arrays | Map session |
-| Internal transform | Rotation/path/scale | Loader / `M2PlacementTransformResolver` | Group/placeholder/instance transforms | Value-only Basis/Vector3 | One placement |
+| 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 |
 | Output | Desired tile/detail operations | Streamer plan application | Finalize queues | Loader-owned | Cross-frame |
 | Output | Terrain/M2/WMO/liquid instances | Loader/builders | Godot world/renderer | Loader/world owner | Main-thread attach |
 | Output | Detached renderer metrics | `WorldRenderFacade` | Capture/baseline tools | Caller-owned deep copy | On demand |
@@ -188,8 +192,9 @@ flowchart TD
     DesiredChunkLod --> ChunkQueue[TerrainChunkGeometryQueuePlanner]
     ChunkQueue --> B
     R --> M2Registry[M2UniquePlacementRegistry reserve]
-    M2Registry --> M2
-    M2Transform[M2PlacementTransformResolver] --> M2
+    M2Registry --> M2Grouper[M2PlacementGrouper]
+    M2Transform[M2PlacementTransformResolver] --> M2Grouper
+    M2Grouper --> M2
     R --> B[RenderBudgetScheduler permits]
     B --> Terrain[Terrain attach/upgrade]
     B --> M2[M2 group/MultiMesh attach]
@@ -305,7 +310,10 @@ sequenceDiagram
   The loader retains owned/skipped tile arrays, candidate retry, grouping/build
   tasks, caches and all MultiMesh/Node/Mesh/material/RID side effects.
 - `M2PlacementTransformResolver` is stateless and retains no resources. The
-  loader owns final transforms and every grouping/build/render side effect.
+  grouper owns worker-path final transforms; direct placeholder/instance
+  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.
 - Rendered-ground query results and diagnostic snapshots are caller-owned values;
   the facade never returns Mesh, Node, tile-state or queue references.
 - Loaded-mesh ground sampling is renderer diagnostics, not authoritative gameplay
@@ -393,6 +401,8 @@ Exact exported settings and cache versions remain documented in [`../../RENDER.m
   bounded reserve/release timing without a world scene.
 - M2 placement transform contract: regular/cliffrock/waterfall formulas, path
   normalization, scale compensation, all three consumers and bounded timing.
+- M2 placement grouper contract: invalid/default records, historical path rules,
+  group order, local transforms, fresh output, source boundary and bounded timing.
 - Budget scheduler contract: exact lane exhaustion, shared chunk removal/create
   priority, independent lanes, frame reset, invalid limits, terminal cancellation,
   dependency boundaries and bounded permit timing without loading a world scene.
@@ -424,6 +434,7 @@ Exact exported settings and cache versions remain documented in [`../../RENDER.m
 | Static M2 placement | Partial | MultiMesh/dedupe probes | Full materials/animation/effects |
 | 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 |
 | WMO rendering | Partial | Cached group rendering | Portals/rooms/material parity |
 | Liquids | Partial | MH2O/MLIQ paths | LiquidType/depth/shore fidelity |
 | Sky/light | Partial | DBC controller/logs | Zone transition paired validation |