render: extract animated M2 materializer

docs/modules/m2-animation-playback-controller.md

@@ -27,8 +27,8 @@ select an imported animation and configure linear looping/playback/seek.
 
 ```mermaid
 flowchart LR
-    Prototype[Animated prototype] --> Loader[StreamingWorldLoader materializer]
-    Loader -->|source and duplicate| Playback[M2AnimationPlaybackController]
+    Prototype[Animated prototype] --> Materializer[M2AnimatedInstanceMaterializer]
+    Materializer -->|source and duplicate| Playback[M2AnimationPlaybackController]
     Finalizer[M2AnimatedSceneFinalizer player inventory] --> Playback
     Playback --> Native[M2NativeAnimator mutation]
     Playback --> Imported[AnimationPlayer mutation]
@@ -52,7 +52,7 @@ MultiMesh, SceneTree attachment and application layers are forbidden.
 
 | Direction | Contract/data | Producer | Consumer | Ownership | Thread/lifetime |
 |---|---|---|---|---|---|
-| Input | Prototype and duplicate subtrees | Loader materializer | Native field copy | Borrowed Nodes | One duplicate |
+| Input | Prototype and duplicate subtrees | M2 animated instance materializer | Native field copy | Borrowed Nodes | One duplicate |
 | Input | Exact native animator Script | Loader composition | Native inventory | Borrowed Script | Call-local |
 | Input | Relative path and instance index | Build batch adapter | Phase/selection | Copied values | One start |
 | Input | AnimationPlayer inventory | Animated scene finalizer traversal | Imported playback | Borrowed players | One start |
@@ -94,29 +94,30 @@ The controller itself is stateless; lifecycle labels describe borrowed instance
 
 ```mermaid
 sequenceDiagram
-    participant L as StreamingWorldLoader
+    participant M as M2AnimatedInstanceMaterializer
     participant F as M2AnimatedSceneFinalizer
     participant P as M2AnimationPlaybackController
     participant N as M2NativeAnimator
     participant A as AnimationPlayer
-    L->>P: copy_native_animator_data(prototype, duplicate, script)
-    L->>F: animation_players_in_subtree(duplicate)
-    F-->>L: ordered players
-    L->>P: start_instance_playback(path, index, players, debug)
+    M->>P: copy_native_animator_data(prototype, duplicate, script)
+    M->>F: animation_players_in_subtree(duplicate)
+    F-->>M: ordered players
+    M->>P: start_instance_playback(path, index, players, debug)
     P->>N: prepare_runtime and set_phase
     P->>A: choose, loop, play and seek
-    P-->>L: optional detached native diagnostics
-    L->>L: preserve existing log format
+    P-->>M: optional detached native diagnostics
+    M-->>M: tag states with instance index
 ```
 
 ## Dependency diagram
 
 ```mermaid
 flowchart TB
-    Loader[StreamingWorldLoader] --> Playback[M2AnimationPlaybackController]
-    Finalizer[M2AnimatedSceneFinalizer] --> Loader
+    Loader[StreamingWorldLoader] --> Materializer[M2AnimatedInstanceMaterializer]
+    Materializer --> Playback[M2AnimationPlaybackController]
+    Materializer --> Finalizer[M2AnimatedSceneFinalizer]
     Playback --> Engine[Node / Script / AnimationPlayer / Animation]
-    Loader --> Batch[SceneTree batch materialization]
+    Materializer --> Batch[SceneTree batch materialization]
     Loader --> NativeScript[M2NativeAnimator script]
     Playback -. no dependency .-> ResourceLoader
     Playback -. no dependency .-> Cache[M2PrototypeCacheState]
@@ -125,8 +126,8 @@ flowchart TB
 
 ## Ownership, threading and resources
 
-- Loader owns prototype duplication, instance/batch roots and SceneTree attachment.
-- Finalizer traversal supplies borrowed AnimationPlayer references.
+- Materializer owns prototype duplication, instance/batch roots and SceneTree attachment.
+- Materializer uses finalizer traversal for borrowed AnimationPlayer references.
 - Controller borrows Nodes/Script/players only for the synchronous call.
 - Native arrays are assigned by reference exactly as before extraction.
 - Diagnostic Dictionaries are deep-duplicated before return.
@@ -185,7 +186,7 @@ for world doodads and compatibility fixtures.
 |---|---|---|---|
 | Imported default selection/playback | Implemented extraction | Synthetic priority/play/seek verifier | Asset-backed animation-name corpus pending |
 | Native data/phase startup | Implemented extraction | Exact-reference/native state verifier | Native visual fidelity remains experimental |
-| Instance/batch materialization | Existing loader-owned | Adjacent build tests | Safe extraction next |
+| Instance/batch materialization | Implemented extraction | Materializer contract verifier | Asset-backed traversal pending |
 
 ## Known gaps and risks
 
@@ -200,7 +201,8 @@ for world doodads and compatibility fixtures.
 | `src/render/m2/m2_animation_playback_controller.gd` | Phase, selection, native copy/start and imported playback |
 | `src/render/m2/m2_animated_scene_finalizer.gd` | Accepted prototype/player inventory |
 | `src/scenes/streaming/m2_native_animator.gd` | Experimental native deformation runtime |
-| `src/scenes/streaming/streaming_world_loader.gd` | Instance duplication/attachment and diagnostic formatting |
+| `src/render/m2/m2_animated_instance_materializer.gd` | Instance duplication/attachment and playback composition |
+| `src/scenes/streaming/streaming_world_loader.gd` | Build adapter, diagnostic formatting and Editor ownership |
 | `src/tools/verify_m2_animation_playback_controller.gd` | Policy/mutation/boundary/timing regression |
 
 ## Related decisions and references