refactor(M03): extract M2 mesh resource cache state

Work-Package: M03-RND-M2-MESH-RESOURCE-CACHE-001
Agent: sindo-main-codex
Tests: 35 headless renderer/coordinate contracts pass; checkpoint dry-run 7/7; documentation and coordination gates pass
Fidelity: preserves exact Mesh references, replacement semantics and final-shutdown lifetime; no visual parity claim

RENDER.md

@@ -37,6 +37,7 @@ Paired run 2026-07-11 подтвердил крупный coordinate/placement g
 - `src/render/liquid/adt_water_scene_finalizer.gd` - stateless main-thread ADT water build/attach and optional persisted Editor ownership through the existing ADTBuilder.
 - `src/render/m2/m2_runtime_mesh_rebuild_classifier.gd` - memoized billboard/UV-rotation decision for stale cached M2 runtime mesh refresh.
 - `src/render/m2/m2_mesh_load_pipeline_state.gd` - static M2 threaded-load request records, terminal statuses and completion-order finalize FIFO without I/O or Mesh ownership.
+- `src/render/m2/m2_mesh_resource_cache_state.gd` - normalized-path prepared static M2 Mesh references with final-shutdown lifetime.
 - `src/scenes/streaming/eastern_kingdoms_streaming.tscn` - текущая сцена для проверки Azeroth/Eastern Kingdoms.
 - `addons/mpq_extractor/loaders/adt_builder.gd` - сборка ADT terrain, control splat материалов и MH2O liquids.
 - `addons/mpq_extractor/loaders/m2_builder.gd` - сборка статического M2 mesh/material.
@@ -1073,6 +1074,19 @@ $exe = Join-Path $env:TEMP 'godot-4.6.1-openwc\Godot_v4.6.1-stable_win64.exe'
 - Cache formats, material refresh, profiles and visible output are unchanged.
   Synthetic state timing is not asset-backed I/O, leak or p95/p99 evidence.
 
+## 2026-07-17 M2 Mesh Resource Cache State Extraction
+
+- `M2MeshResourceCacheState` now owns normalized-path references to prepared
+  static M2 Mesh resources. Lookup returns the exact retained reference and a
+  later store for one path keeps the historical replacement behavior.
+- The cache retains map-refresh lifetime and clears only at the existing final
+  runtime-cache shutdown site after asynchronous work is drained.
+- `StreamingWorldLoader` still owns normalization, `.tscn`/`.glb` selection,
+  ResourceLoader I/O, Mesh extraction, material refresh/rebuild, shared missing
+  and prototype/animated caches, permits and MultiMesh materialization.
+- Cache formats, refresh metadata, profiles and visible output are unchanged.
+  Synthetic cache timing is not asset-backed memory/leak or p95/p99 evidence.
+
 ## 2026-07-17 WMO Placement Resolver Extraction
 
 - `WmoPlacementResolver` now owns lowercase/slash cache-key normalization,

coordination/claims/M03-RND-M2-MESH-RESOURCE-CACHE-001.md

@@ -30,6 +30,8 @@ all existing cache consumers.
   `src/tools/verify_m2_mesh_resource_cache_state.gd`,
   `docs/modules/m2-mesh-resource-cache-state.md`, this claim
 - Shared/hotspots: `src/scenes/streaming/streaming_world_loader.gd`,
+  `src/tools/verify_m2_mesh_load_pipeline_state.gd`,
+  `src/tools/verify_render_runtime_cache_shutdown.gd`,
   `docs/modules/world-renderer.md`, `docs/modules/README.md`, `RENDER.md`,
   `targets/03-renderer-facade.md`
 - Generated/ignored: `.godot`, native DLL, generated M2 resources, caches and

docs/modules/README.md

@@ -23,6 +23,7 @@
 | M2 build batch planner | Implemented extraction | [`m2-build-batch-planner.md`](m2-build-batch-planner.md) |
 | M2 runtime mesh rebuild classifier | Implemented extraction | [`m2-runtime-mesh-rebuild-classifier.md`](m2-runtime-mesh-rebuild-classifier.md) |
 | M2 mesh load pipeline state | Implemented extraction | [`m2-mesh-load-pipeline-state.md`](m2-mesh-load-pipeline-state.md) |
+| M2 mesh resource cache state | Implemented extraction | [`m2-mesh-resource-cache-state.md`](m2-mesh-resource-cache-state.md) |
 | WMO placement resolver | Implemented extraction | [`wmo-placement-resolver.md`](wmo-placement-resolver.md) |
 | WMO placement registry | Implemented extraction | [`wmo-placement-registry.md`](wmo-placement-registry.md) |
 | WMO render build step planner | Implemented extraction | [`wmo-render-build-step-planner.md`](wmo-render-build-step-planner.md) |

docs/modules/m2-mesh-load-pipeline-state.md

@@ -19,7 +19,7 @@ loader retains every I/O and engine-resource operation.
 ## Non-goals
 
 - Call ResourceLoader or select cache paths/formats.
-- Own M2 Mesh, scene, missing or material-refresh caches.
+- Own M2 scene, missing or material-refresh caches, or prepared Mesh references.
 - Extract Meshes from PackedScene/GLB Resources.
 - Consume finalize permits or rebuild/adopt runtime Meshes.
 - Merge static and animated M2 pipelines.
@@ -38,7 +38,7 @@ flowchart LR
     State --> FIFO[Finalize FIFO]
     FIFO --> Loader
     Loader --> Budget[M2_MESH_FINALIZE permit]
-    Loader --> Cache[Mesh or missing cache]
+    Loader --> Cache[M2 Mesh resource cache or shared missing cache]
 ```
 
 Allowed dependencies are value containers, Strings and opaque integer statuses.
@@ -135,7 +135,7 @@ flowchart TB
     Loader[StreamingWorldLoader] --> State[M2MeshLoadPipelineState]
     Loader --> Resource[ResourceLoader]
     Loader --> Budget[RenderBudgetScheduler]
-    Loader --> MeshCache[M2 Mesh/missing caches]
+    Loader --> MeshCache[M2 Mesh resource cache and shared missing cache]
     Loader --> Classifier[M2RuntimeMeshRebuildClassifier]
     State -. no dependency .-> Resource
     State -. no dependency .-> Budget
@@ -147,7 +147,8 @@ flowchart TB
 - Main thread serializes all state mutation and snapshots.
 - State owns only request/finalize Dictionaries containing Strings and status integers.
 - Loader owns ResourceLoader request lifetime and drains active paths before shutdown clear.
-- Loader owns Mesh/missing caches, material refresh, M2Builder and engine resources.
+- `M2MeshResourceCacheState` owns prepared static Mesh references; the loader
+  owns shared missing state, material refresh, M2Builder and other engine resources.
 - Snapshot and diagnostic records are detached; caller mutation cannot affect state.
 
 ## Errors, cancellation and recovery
@@ -202,7 +203,8 @@ rebuild policy are unchanged; no migration or rebake is required.
 |---|---|---|---|
 | Static M2 request/finalize state | Implemented extraction | Contract/source/timing verifier | Asset-backed long traversal pending |
 | ResourceLoader I/O | Existing loader-owned | Shutdown/material regressions | I/O adapter extraction optional |
-| Mesh cache/materialization | Existing loader-owned | Renderer/material tests | Separate state/finalizer extraction pending |
+| Mesh cache | Implemented extraction | Mesh resource cache state verifier | Asset-backed memory/leak run pending |
+| Mesh materialization | Existing loader-owned | Renderer/material tests | Separate finalizer extraction pending |
 
 ## Known gaps and risks
 
@@ -216,6 +218,7 @@ rebuild policy are unchanged; no migration or rebake is required.
 | Path | Responsibility |
 |---|---|
 | `src/render/m2/m2_mesh_load_pipeline_state.gd` | Pending records, terminal FIFO and metrics |
+| `src/render/m2/m2_mesh_resource_cache_state.gd` | Prepared static Mesh references and final clear |
 | `src/scenes/streaming/streaming_world_loader.gd` | Cache path choice, I/O polling, permits and Mesh/missing adoption |
 | `src/render/m2/m2_runtime_mesh_rebuild_classifier.gd` | Downstream stale Mesh rebuild decision |
 | `src/tools/verify_m2_mesh_load_pipeline_state.gd` | Lifecycle/boundary/timing regression |

docs/modules/m2-mesh-resource-cache-state.md

@@ -0,0 +1,209 @@
+# M2 Mesh Resource Cache State
+
+## Metadata
+
+| Field | Value |
+|---|---|
+| Status | Implemented extraction |
+| Target/work package | M03 / `M03-RND-M2-MESH-RESOURCE-CACHE-001` |
+| Owners | Prepared static M2 Mesh resource references by normalized path |
+| Last verified | Worktree `work/sindo-main-codex/m03-m2-mesh-resource-cache`, 2026-07-17 |
+| Profiles/capabilities | Existing static M2 cached and raw fallback paths |
+
+## Purpose
+
+Own the runtime cache of prepared static M2 `Mesh` references outside
+`StreamingWorldLoader`. The loader remains responsible for finding, loading,
+extracting, refreshing and materializing each Mesh.
+
+## Non-goals
+
+- Own the shared M2 missing-path, prototype or animated-scene caches.
+- Call ResourceLoader/FileAccess or select `.tscn`/`.glb` paths.
+- Extract a Mesh from a Resource or Node.
+- Refresh materials, rebuild Meshes or create MultiMesh instances.
+- Add eviction, persistence, cache versions or quality-profile behavior.
+
+## Context and boundaries
+
+```mermaid
+flowchart LR
+    Need[Static M2 mesh lookup] --> Loader[StreamingWorldLoader]
+    Loader --> Cache[M2MeshResourceCacheState]
+    Cache -->|cached Mesh or null| Loader
+    Loader --> Pipeline[M2MeshLoadPipelineState]
+    Pipeline --> IO[ResourceLoader]
+    IO --> Prepare[Loader extraction and runtime preparation]
+    Prepare --> Cache
+    Loader --> Build[M2 MultiMesh materialization]
+```
+
+The cache may retain `Mesh` resources and copied normalized-path Strings. It has
+no Node, ResourceLoader, filesystem, worker, scheduler, missing-state, builder,
+gameplay, network or editor dependency.
+
+## Public API
+
+| Symbol | Kind | Purpose | Thread/lifetime | Errors |
+|---|---|---|---|---|
+| `store_mesh(path, mesh)` | Command/query | Retain or replace one prepared Mesh | Renderer main thread; final shutdown | Empty path/null Mesh rejected |
+| `has_mesh(path)` | Query | Test whether a Mesh is retained | Renderer main thread | Empty/unknown false |
+| `find_mesh(path)` | Query | Borrow exact retained Mesh reference | Renderer main thread | Empty/unknown null |
+| `mesh_count()` | Query | Return retained entry count | Diagnostics/tests | None |
+| `normalized_paths_snapshot()` | Query | Copy insertion-order path keys | Diagnostics/tests | Never exposes Mesh references |
+| `clear()` | Command | Release every retained Mesh reference | Final shutdown after async drain | Idempotent |
+
+## Inputs and outputs
+
+| Direction | Contract/data | Producer | Consumer | Ownership | Thread/lifetime |
+|---|---|---|---|---|---|
+| Input | Normalized relative M2 path | Loader normalization adapter | Cache key | Copied String | Cache lifetime |
+| Input | Prepared static Mesh | Loader finalizer or synchronous fallback | Cache value | Strong reference retained | Until replacement/clear |
+| Output | Borrowed exact Mesh | Cache lookup | Static M2 batch builder | Cache retains reference | One build/materialization pass |
+| Output | Detached normalized paths | Cache diagnostics | Verifier/future metrics | Caller-owned Strings | Snapshot lifetime |
+
+Store and clear mutate only the cache Dictionary and Resource reference counts.
+
+## Data flow
+
+```mermaid
+flowchart TD
+    Lookup[Lookup normalized M2 path] --> Cached{Mesh cached?}
+    Cached -->|yes| Return[Return retained Mesh]
+    Cached -->|no| Missing{Shared missing state?}
+    Missing -->|yes| Null[Return null]
+    Missing -->|no| Load[Loader request or synchronous fallback]
+    Load --> Prepare[Loader extracts and prepares Mesh]
+    Prepare --> Valid{Prepared Mesh valid?}
+    Valid -->|yes| Store[Store or replace cache entry]
+    Valid -->|no| MarkMissing[Loader updates shared missing state]
+    Store --> Return
+```
+
+## Lifecycle/state
+
+```mermaid
+stateDiagram-v2
+    [*] --> Absent
+    Absent --> Cached: store valid Mesh
+    Cached --> Cached: replace Mesh reference
+    Cached --> Absent: final shutdown clear
+```
+
+Map/world refresh retains cached Meshes. Only the existing final runtime-cache
+release clears them after asynchronous shutdown drain.
+
+## Main sequence
+
+```mermaid
+sequenceDiagram
+    participant Loader as StreamingWorldLoader
+    participant Cache as M2MeshResourceCacheState
+    participant Pipeline as M2MeshLoadPipelineState
+    Loader->>Cache: find/has normalized path
+    alt cache miss
+        Loader->>Pipeline: request/poll/finalize record
+        Loader->>Loader: ResourceLoader get + extract + prepare
+        Loader->>Cache: store_mesh(path, prepared Mesh)
+    end
+    Cache-->>Loader: exact retained Mesh
+    Loader->>Loader: materialize static M2 batch
+```
+
+## Dependency diagram
+
+```mermaid
+flowchart TB
+    Loader[StreamingWorldLoader] --> Cache[M2MeshResourceCacheState]
+    Loader --> Pipeline[M2MeshLoadPipelineState]
+    Loader --> Classifier[M2RuntimeMeshRebuildClassifier]
+    Loader --> Builder[M2Builder and MultiMesh]
+    Cache --> Mesh[Godot Mesh Resource]
+    Cache -. no dependency .-> Pipeline
+    Cache -. no dependency .-> Classifier
+    Cache -. no dependency .-> Builder
+```
+
+## Ownership, threading and resources
+
+- Renderer main-thread adapters serialize every cache operation.
+- The cache owns normalized-path Strings and strong Mesh references.
+- Borrowed Mesh lookups do not transfer ownership or duplicate resources.
+- The loader owns missing/prototype/animated state and all Nodes/MultiMeshes.
+- The loader drains asynchronous work before the final cache clear.
+
+## Errors, cancellation and recovery
+
+| Failure/state | Detection | Behavior | Diagnostic | Recovery |
+|---|---|---|---|---|
+| Empty path or null Mesh | Cache guard | Reject unchanged | Contract verifier | Correct caller input |
+| Unknown lookup | Membership query | Return null | Existing loader path | Request/load or missing decision |
+| Replacement | Existing key | Retain new exact reference | Contract verifier | Normal subsequent lookup |
+| Load/preparation failure | Loader boundary | Do not store; loader marks missing | Existing renderer behavior | Cache/source correction and reload |
+| Final shutdown | Loader lifecycle | Clear releases references | Shutdown/source verifier | New loader starts empty |
+
+## Configuration and capabilities
+
+The module adds no setting, budget or profile branch. Cache path order,
+`M2_MATERIAL_REFRESH_VERSION`, finalize permits and batching remain loader-owned.
+
+## Persistence, cache and migration
+
+The state is runtime-only and serializes nothing. Existing `.tscn`/`.glb`
+formats, import caches and material refresh metadata are unchanged; no migration
+or rebake is required.
+
+## Diagnostics and observability
+
+`mesh_count` and `normalized_paths_snapshot` expose scalar ownership diagnostics
+without Mesh references. Existing renderer metrics/logging are unchanged because
+the historical Mesh cache had no queue contribution or log site.
+
+## Verification
+
+- `verify_m2_mesh_resource_cache_state.gd`: invalid input, exact reference,
+  replacement, lookup, detached path snapshot, idempotent clear, loader source
+  ownership and 100-by-256 bounded timing.
+- Mesh pipeline/classifier/material/shutdown/M2 build/facade regressions cover
+  adjacent behavior.
+- Fidelity evidence is exact cache/lifetime extraction; no original-client
+  visual-parity or asset-backed performance claim is made.
+
+## Extension points
+
+- A separate M2 Mesh resource finalizer may later return a prepared Mesh for
+  `store_mesh` without changing cache ownership.
+- Eviction requires measured memory pressure and explicit lifetime semantics.
+
+## Capability status
+
+| Capability | Status | Evidence | Gap/next step |
+|---|---|---|---|
+| Prepared static M2 Mesh cache | Implemented extraction | Contract/source/timing verifier | Asset-backed memory/leak run pending |
+| M2 Mesh request lifecycle | Implemented extraction | Pipeline state verifier | ResourceLoader I/O remains loader-owned |
+| M2 Mesh extraction/preparation | Existing loader-owned | Material/classifier regressions | Separate finalizer extraction next |
+
+## Known gaps and risks
+
+- Strong Mesh references intentionally remain until final shutdown.
+- Shared missing state cannot move here without also redesigning prototype and
+  animated lookup behavior.
+- No proprietary M2 traversal, leak/descriptor-pressure, p95/p99 or paired
+  original-client capture is included.
+
+## Source map
+
+| Path | Responsibility |
+|---|---|
+| `src/render/m2/m2_mesh_resource_cache_state.gd` | Prepared Mesh references and final clear |
+| `src/scenes/streaming/streaming_world_loader.gd` | Normalization, I/O, preparation, missing state and materialization |
+| `src/render/m2/m2_mesh_load_pipeline_state.gd` | Pending request and terminal finalize records |
+| `src/tools/verify_m2_mesh_resource_cache_state.gd` | Cache ownership/lifetime/boundary/timing regression |
+
+## Related decisions and references
+
+- [`m2-mesh-load-pipeline-state.md`](m2-mesh-load-pipeline-state.md)
+- [`m2-runtime-mesh-rebuild-classifier.md`](m2-runtime-mesh-rebuild-classifier.md)
+- [`world-renderer.md`](world-renderer.md)
+- [`../../RENDER.md`](../../RENDER.md)
+- [`../../targets/roadmap/02-rendering-and-graphics.md`](../../targets/roadmap/02-rendering-and-graphics.md)

docs/modules/world-renderer.md

@@ -7,7 +7,7 @@
 | 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 packages; M03 WMO placement package |
 | Owners | Renderer workstream / milestone integrator |
-| Last verified | Worktree `work/sindo-main-codex/m03-m2-mesh-load-pipeline`, 2026-07-17 |
+| Last verified | Worktree `work/sindo-main-codex/m03-m2-mesh-resource-cache`, 2026-07-17 |
 | Profiles/capabilities | `Performance`, `Balanced`, `High`, `Custom`; Blizzlike fidelity incomplete |
 
 ## Purpose
@@ -134,6 +134,7 @@ from externally reading/writing loader-private queue, task, cache and tile-state
 | `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 |
 | `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 |
 | `M2MeshLoadPipelineState` | Internal M2 async-state service | Owns static Mesh pending request records and terminal finalize FIFO | Renderer main thread; map/session | Empty/duplicate/unknown transitions rejected |
+| `M2MeshResourceCacheState` | Internal M2 Resource cache | Owns prepared static Mesh references by normalized path | Renderer main thread; final shutdown | Empty path/null Mesh rejected; same path replaces |
 | `WmoPlacementResolver.normalize_relative_path/resolve_unique_key/resolve_world_transform` | Internal pure WMO service | Resolves cache key, registry identity and world transform | Main/any thread; stateless | Missing UID uses tile/index fallback; transform fields use historical defaults |
 | `WmoPlacementRegistry.add_reference/release_reference/contains/active_count/diagnostic_snapshot/clear` | Internal WMO service | Owns placement-key to tile/global reference sets | Renderer main thread; map session | Empty/unknown/non-owner input is rejected without mutation |
 | `WmoRenderBuildStepPlanner.plan_step` | Internal pure WMO service | Selects one mesh-first lightweight render-group operation and next cursors | Main/any thread; stateless | Raw integer comparisons are preserved without clamping |
@@ -372,7 +373,10 @@ sequenceDiagram
   refresh-version checks, Mesh rebuild/adoption and both historical clear sites.
 - `M2MeshLoadPipelineState` owns static M2 pending Resource paths, opaque
   terminal statuses and completion-order finalize FIFO. The loader retains cache
-  path selection, ResourceLoader calls, permits, Mesh/missing caches and adoption.
+  path selection, ResourceLoader calls, permits, shared missing state and adoption.
+- `M2MeshResourceCacheState` owns prepared static Mesh references and releases
+  them at the existing final-shutdown site. The loader retains extraction,
+  material refresh/rebuild, missing/prototype state and materialization.
 - 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
@@ -575,6 +579,7 @@ Exact exported settings and cache versions remain documented in [`../../RENDER.m
 | `src/render/liquid/adt_water_scene_finalizer.gd` | Main-thread ADT water build, tile attachment and optional editor ownership |
 | `src/render/m2/m2_runtime_mesh_rebuild_classifier.gd` | Billboard/UV-rotation stale cached-mesh rebuild decision and memoization |
 | `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/streaming/streaming_target_planner.gd` | Scene-free wanted/retained ADT target calculation |
 | `src/render/streaming/streaming_target_policy.gd` | Immutable renderer radius/prefetch policy |
 | `src/render/streaming/streaming_target_plan.gd` | Immutable planner result with read-only tile-key sets |
@@ -591,6 +596,7 @@ Exact exported settings and cache versions remain documented in [`../../RENDER.m
 | `src/tools/verify_adt_water_scene_finalizer.gd` | Synthetic ADT water scene/ownership/boundary/timing regression |
 | `src/tools/verify_m2_runtime_mesh_rebuild_classifier.gd` | M2 rebuild predicate/cache/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_streaming_target_planner.gd` | Planner behavior, dependency and bounded timing regression |
 | `src/tools/verify_render_budget_scheduler.gd` | Scheduler bounds, shared-lane priority, cancellation and timing regression |
 | `src/tools/verify_renderer_internal_access.gd` | Gameplay/EditorPlugin/registered renderer-tool boundary gate derived from private streamer fields |

src/render/m2/m2_mesh_resource_cache_state.gd

@@ -0,0 +1,50 @@
+class_name M2MeshResourceCacheState
+extends RefCounted
+
+## Owns normalized-path references to prepared static M2 Mesh resources.
+## The caller owns loading, preparation, missing-state and materialization.
+
+var _mesh_by_normalized_path: Dictionary = {}
+
+
+## Stores one prepared Mesh for a non-empty normalized M2 path. A later store
+## for the same path replaces the retained reference.
+func store_mesh(normalized_relative_path: String, mesh: Mesh) -> bool:
+	if normalized_relative_path.is_empty() or mesh == null:
+		return false
+	_mesh_by_normalized_path[normalized_relative_path] = mesh
+	return true
+
+
+## Returns whether one normalized path currently has a retained Mesh.
+func has_mesh(normalized_relative_path: String) -> bool:
+	return (
+		not normalized_relative_path.is_empty()
+		and _mesh_by_normalized_path.has(normalized_relative_path)
+	)
+
+
+## Returns the exact retained Mesh reference, or null for empty/unknown paths.
+func find_mesh(normalized_relative_path: String) -> Mesh:
+	if not has_mesh(normalized_relative_path):
+		return null
+	return _mesh_by_normalized_path[normalized_relative_path] as Mesh
+
+
+## Returns the number of retained static M2 Mesh resources.
+func mesh_count() -> int:
+	return _mesh_by_normalized_path.size()
+
+
+## Returns a detached insertion-order list of cached normalized paths.
+func normalized_paths_snapshot() -> Array[String]:
+	var normalized_paths: Array[String] = []
+	for normalized_path_variant in _mesh_by_normalized_path.keys():
+		normalized_paths.append(String(normalized_path_variant))
+	return normalized_paths
+
+
+## Releases all retained Mesh references. The loader calls this only after
+## asynchronous work has completed during final scene shutdown.
+func clear() -> void:
+	_mesh_by_normalized_path.clear()

src/render/m2/m2_mesh_resource_cache_state.gd.uid

@@ -0,0 +1 @@
+uid://dhkyjcrdblgkd

src/scenes/streaming/streaming_world_loader.gd

@@ -66,6 +66,9 @@ const M2_RUNTIME_MESH_REBUILD_CLASSIFIER_SCRIPT := preload(
 const M2_MESH_LOAD_PIPELINE_STATE_SCRIPT := preload(
 	"res://src/render/m2/m2_mesh_load_pipeline_state.gd"
 )
+const M2_MESH_RESOURCE_CACHE_STATE_SCRIPT := preload(
+	"res://src/render/m2/m2_mesh_resource_cache_state.gd"
+)
 const STREAMING_TARGET_PLANNER_SCRIPT := preload("res://src/render/streaming/streaming_target_planner.gd")
 const STREAMING_TARGET_POLICY_SCRIPT := preload("res://src/render/streaming/streaming_target_policy.gd")
 const RENDER_BUDGET_SCHEDULER_SCRIPT := preload("res://src/render/streaming/render_budget_scheduler.gd")
@@ -256,7 +259,7 @@ var _m2_build_batch_planner := M2_BUILD_BATCH_PLANNER_SCRIPT.new()
 var _m2_runtime_mesh_rebuild_classifier := (
 	M2_RUNTIME_MESH_REBUILD_CLASSIFIER_SCRIPT.new()
 )
-var _m2_mesh_cache: Dictionary = {}
+var _m2_mesh_resource_cache_state := M2_MESH_RESOURCE_CACHE_STATE_SCRIPT.new()
 var _m2_mesh_load_pipeline_state := M2_MESH_LOAD_PIPELINE_STATE_SCRIPT.new()
 var _m2_animation_load_requests: Dictionary = {}
 var _m2_animation_finalize_queue: Array = []
@@ -476,7 +479,7 @@ func _release_runtime_caches_for_shutdown() -> void:
 	_free_detached_node_cache(_m2_scene_cache)
 	_free_detached_node_cache(_m2_animated_scene_cache)
 	_free_detached_node_cache(_wmo_prototype_cache)
-	_m2_mesh_cache.clear()
+	_m2_mesh_resource_cache_state.clear()
 	_m2_static_animation_cache.clear()
 	_m2_missing_cache.clear()
 	_wmo_render_resource_cache_state.clear_all()
@@ -4263,7 +4266,10 @@ func _drain_m2_mesh_loads() -> void:
 			RENDER_BUDGET_SCHEDULER_SCRIPT.M2_MESH_FINALIZE):
 		var pending: Dictionary = _m2_mesh_load_pipeline_state.pop_finalize_record()
 		var normalized_rel := String(pending.get("normalized", ""))
-		if normalized_rel.is_empty() or _m2_mesh_cache.has(normalized_rel):
+		if (
+			normalized_rel.is_empty()
+			or _m2_mesh_resource_cache_state.has_mesh(normalized_rel)
+		):
 			continue
 		if int(pending.get("status", ResourceLoader.THREAD_LOAD_FAILED)) != ResourceLoader.THREAD_LOAD_LOADED:
 			_m2_missing_cache[normalized_rel] = true
@@ -4273,7 +4279,10 @@ func _drain_m2_mesh_loads() -> void:
 		var resource: Resource = ResourceLoader.load_threaded_get(path)
 		var mesh := _extract_first_mesh_from_m2_resource(resource)
 		if mesh != null:
-			_m2_mesh_cache[normalized_rel] = _prepare_m2_mesh_for_runtime(normalized_rel, mesh)
+			_m2_mesh_resource_cache_state.store_mesh(
+				normalized_rel,
+				_prepare_m2_mesh_for_runtime(normalized_rel, mesh)
+			)
 		else:
 			_m2_missing_cache[normalized_rel] = true
 
@@ -4608,8 +4617,8 @@ func _get_m2_mesh_or_request(rel_path: String) -> Mesh:
 	var normalized_rel := _normalize_m2_rel_path(rel_path)
 	if normalized_rel.is_empty():
 		return null
-	if _m2_mesh_cache.has(normalized_rel):
-		return _m2_mesh_cache[normalized_rel]
+	if _m2_mesh_resource_cache_state.has_mesh(normalized_rel):
+		return _m2_mesh_resource_cache_state.find_mesh(normalized_rel)
 	if _m2_missing_cache.has(normalized_rel):
 		return null
 	_request_m2_mesh_load(normalized_rel)
@@ -4716,15 +4725,15 @@ func _find_first_mesh_recursive(node: Node) -> Mesh:
 
 func _get_or_load_m2_mesh(rel_path: String) -> Mesh:
 	var normalized_rel := _normalize_m2_rel_path(rel_path)
-	if _m2_mesh_cache.has(normalized_rel):
-		return _m2_mesh_cache[normalized_rel]
+	if _m2_mesh_resource_cache_state.has_mesh(normalized_rel):
+		return _m2_mesh_resource_cache_state.find_mesh(normalized_rel)
 	var prototype: Node3D = _get_or_load_m2_prototype(rel_path)
 	if prototype == null:
 		return null
 	var mesh := _find_first_mesh_recursive(prototype)
 	if mesh != null and not normalized_rel.is_empty():
 		mesh = _prepare_m2_mesh_for_runtime(normalized_rel, mesh)
-		_m2_mesh_cache[normalized_rel] = mesh
+		_m2_mesh_resource_cache_state.store_mesh(normalized_rel, mesh)
 	return mesh
 
 

src/tools/verify_m2_mesh_load_pipeline_state.gd

@@ -110,7 +110,7 @@ func _verify_ownership_boundaries(failures: Array[String]) -> void:
 		"ResourceLoader.load_threaded_get_status(path)",
 		"ResourceLoader.load_threaded_get(path)",
 		"RENDER_BUDGET_SCHEDULER_SCRIPT.M2_MESH_FINALIZE",
-		"_m2_mesh_cache[normalized_rel]",
+		"_m2_mesh_resource_cache_state.store_mesh(",
 		"_m2_missing_cache[normalized_rel]",
 	]:
 		_expect_true(loader_source.contains(retained_loader_rule), "loader retains %s" % retained_loader_rule, failures)
@@ -121,6 +121,7 @@ func _verify_ownership_boundaries(failures: Array[String]) -> void:
 		"Node3D",
 		"RID(",
 		"_m2_mesh_cache",
+		"_m2_mesh_resource_cache_state",
 		"_m2_missing_cache",
 	]:
 		_expect_false(

src/tools/verify_m2_mesh_resource_cache_state.gd

@@ -0,0 +1,158 @@
+extends SceneTree
+
+## Synthetic ownership/lifetime/boundary/timing regression for the prepared
+## static M2 Mesh resource cache.
+
+const CACHE_SCRIPT := preload("res://src/render/m2/m2_mesh_resource_cache_state.gd")
+const CACHE_PATH := "res://src/render/m2/m2_mesh_resource_cache_state.gd"
+const LOADER_PATH := "res://src/scenes/streaming/streaming_world_loader.gd"
+
+
+func _initialize() -> void:
+	var failures: Array[String] = []
+	_verify_validation_store_lookup_and_replace(failures)
+	_verify_clear_and_diagnostics(failures)
+	_verify_ownership_boundaries(failures)
+	var elapsed_milliseconds := _verify_bounded_timing(failures)
+	if not failures.is_empty():
+		for failure in failures:
+			push_error("M2_MESH_RESOURCE_CACHE_STATE: %s" % failure)
+		quit(1)
+		return
+	print(
+		"M2_MESH_RESOURCE_CACHE_STATE PASS cases=9 iterations=100 elapsed_ms=%.3f"
+		% elapsed_milliseconds
+	)
+	quit(0)
+
+
+func _verify_validation_store_lookup_and_replace(failures: Array[String]) -> void:
+	var cache: RefCounted = CACHE_SCRIPT.new()
+	var first_mesh := ArrayMesh.new()
+	var replacement_mesh := ArrayMesh.new()
+	_expect_false(cache.call("store_mesh", "", first_mesh), "empty path rejected", failures)
+	_expect_false(cache.call("store_mesh", "world/a.m2", null), "null Mesh rejected", failures)
+	_expect_true(cache.call("store_mesh", "world/a.m2", first_mesh), "first Mesh stored", failures)
+	_expect_true(cache.call("has_mesh", "world/a.m2"), "stored Mesh observable", failures)
+	_expect_same(cache.call("find_mesh", "world/a.m2"), first_mesh, "exact Mesh retained", failures)
+	_expect_true(
+		cache.call("store_mesh", "world/a.m2", replacement_mesh),
+		"same-path Mesh replaced",
+		failures
+	)
+	_expect_same(
+		cache.call("find_mesh", "world/a.m2"),
+		replacement_mesh,
+		"replacement Mesh retained",
+		failures
+	)
+	_expect_equal(int(cache.call("mesh_count")), 1, "replacement keeps one entry", failures)
+	_expect_same(cache.call("find_mesh", "world/missing.m2"), null, "unknown path returns null", failures)
+
+
+func _verify_clear_and_diagnostics(failures: Array[String]) -> void:
+	var cache: RefCounted = CACHE_SCRIPT.new()
+	cache.call("store_mesh", "world/a.m2", ArrayMesh.new())
+	cache.call("store_mesh", "world/b.m2", ArrayMesh.new())
+	var normalized_paths: Array[String] = cache.call("normalized_paths_snapshot")
+	_expect_equal(normalized_paths.size(), 2, "diagnostic path count", failures)
+	_expect_string_equal(normalized_paths[0], "world/a.m2", "diagnostic insertion order first", failures)
+	_expect_string_equal(normalized_paths[1], "world/b.m2", "diagnostic insertion order second", failures)
+	normalized_paths.clear()
+	_expect_equal(int(cache.call("mesh_count")), 2, "diagnostics detached", failures)
+	cache.call("clear")
+	cache.call("clear")
+	_expect_equal(int(cache.call("mesh_count")), 0, "clear releases all entries", failures)
+
+
+func _verify_ownership_boundaries(failures: Array[String]) -> void:
+	var cache_source := FileAccess.get_file_as_string(CACHE_PATH)
+	var loader_source := FileAccess.get_file_as_string(LOADER_PATH)
+	_expect_true(
+		loader_source.contains("M2_MESH_RESOURCE_CACHE_STATE_SCRIPT.new()"),
+		"loader composes Mesh cache state",
+		failures
+	)
+	_expect_false(loader_source.contains("var _m2_mesh_cache:"), "legacy Mesh cache removed", failures)
+	_expect_equal(
+		loader_source.count("_m2_mesh_resource_cache_state.store_mesh("),
+		2,
+		"two existing stores delegate",
+		failures
+	)
+	_expect_equal(
+		loader_source.count("_m2_mesh_resource_cache_state.find_mesh("),
+		2,
+		"two existing lookups delegate",
+		failures
+	)
+	_expect_equal(
+		loader_source.count("_m2_mesh_resource_cache_state.clear()"),
+		1,
+		"final shutdown clear delegates",
+		failures
+	)
+	for retained_loader_rule in [
+		"ResourceLoader.load_threaded_get(path)",
+		"_extract_first_mesh_from_m2_resource(resource)",
+		"_prepare_m2_mesh_for_runtime(normalized_rel, mesh)",
+		"_m2_missing_cache[normalized_rel]",
+		"_m2_scene_cache[normalized_rel]",
+	]:
+		_expect_true(loader_source.contains(retained_loader_rule), "loader retains %s" % retained_loader_rule, failures)
+	for forbidden_dependency in [
+		"ResourceLoader.",
+		"FileAccess.",
+		"WorkerThreadPool.",
+		"PackedScene",
+		"Node3D",
+		"M2Builder",
+		"_m2_missing_cache",
+		"_m2_scene_cache",
+	]:
+		_expect_false(
+			cache_source.contains(forbidden_dependency),
+			"cache omits %s ownership" % forbidden_dependency,
+			failures
+		)
+
+
+func _verify_bounded_timing(failures: Array[String]) -> float:
+	var cache: RefCounted = CACHE_SCRIPT.new()
+	var meshes: Array[Mesh] = []
+	for _path_index in range(256):
+		meshes.append(ArrayMesh.new())
+	var started_microseconds := Time.get_ticks_usec()
+	for _iteration in range(100):
+		for path_index in range(256):
+			cache.call("store_mesh", "world/model_%d.m2" % path_index, meshes[path_index])
+		for path_index in range(256):
+			cache.call("find_mesh", "world/model_%d.m2" % path_index)
+		cache.call("clear")
+	var elapsed_milliseconds := float(Time.get_ticks_usec() - started_microseconds) / 1000.0
+	_expect_true(elapsed_milliseconds < 1000.0, "100 by 256 store/lookups under 1 second", failures)
+	return elapsed_milliseconds
+
+
+func _expect_true(condition: bool, label: String, failures: Array[String]) -> void:
+	if not condition:
+		failures.append(label)
+
+
+func _expect_false(condition: bool, label: String, failures: Array[String]) -> void:
+	_expect_true(not condition, label, failures)
+
+
+func _expect_equal(actual: int, expected: int, label: String, failures: Array[String]) -> void:
+	if actual != expected:
+		failures.append("%s expected=%d actual=%d" % [label, expected, actual])
+
+
+func _expect_string_equal(actual: String, expected: String, label: String, failures: Array[String]) -> void:
+	if actual != expected:
+		failures.append("%s expected=%s actual=%s" % [label, expected, actual])
+
+
+func _expect_same(actual: Variant, expected: Variant, label: String, failures: Array[String]) -> void:
+	if not is_same(actual, expected):
+		failures.append(label)

src/tools/verify_m2_mesh_resource_cache_state.gd.uid

@@ -0,0 +1 @@
+uid://ld4k7pnaueno

src/tools/verify_render_runtime_cache_shutdown.gd

@@ -35,7 +35,8 @@ func _verify_runtime_cache_ownership() -> void:
 	loader.set("_m2_scene_cache", {"static": static_m2_prototype})
 	loader.set("_m2_animated_scene_cache", {"animated": animated_m2_prototype})
 	loader.set("_wmo_prototype_cache", {"wmo": wmo_prototype})
-	loader.set("_m2_mesh_cache", {"mesh": ArrayMesh.new()})
+	var m2_mesh_resource_cache_state: RefCounted = loader.get("_m2_mesh_resource_cache_state")
+	m2_mesh_resource_cache_state.call("store_mesh", "mesh", ArrayMesh.new())
 	loader.set("_m2_static_animation_cache", {"static": true})
 	loader.set("_m2_missing_cache", {"missing": true})
 	var wmo_render_cache_state: RefCounted = loader.get("_wmo_render_resource_cache_state")
@@ -59,7 +60,6 @@ func _verify_runtime_cache_ownership() -> void:
 		"_m2_scene_cache",
 		"_m2_animated_scene_cache",
 		"_wmo_prototype_cache",
-		"_m2_mesh_cache",
 		"_m2_static_animation_cache",
 		"_m2_missing_cache",
 		"_wmo_missing_cache",
@@ -67,6 +67,10 @@ func _verify_runtime_cache_ownership() -> void:
 	]:
 		var cache: Dictionary = loader.get(cache_name)
 		_expect(cache.is_empty(), "%s should be empty after shutdown" % cache_name)
+	_expect(
+		int(m2_mesh_resource_cache_state.call("mesh_count")) == 0,
+		"M2 Mesh Resources should be empty after shutdown"
+	)
 	var wmo_render_snapshot: Dictionary = wmo_render_cache_state.call("diagnostic_snapshot")
 	_expect(
 		(wmo_render_snapshot["resource_paths"] as Array).is_empty(),