# WMO Runtime Mesh Finalizer

## Metadata

| Field | Value |
|---|---|
| Status | Implemented extraction |
| Target/work package | M03 / `M03-RND-WMO-RUNTIME-MESH-FINALIZER-001` |
| Owners | Cached WMO runtime Mesh refresh version, surface iteration and material reconstruction |
| Last verified | Worktree `work/sindo-main-codex/m03-wmo-runtime-mesh-finalizer`, 2026-07-18 |
| Profiles/capabilities | Profile-independent cached WMO material refresh |

## Purpose

Finalize stale cached WMO runtime Mesh materials outside
`StreamingWorldLoader`: preserve exact Mesh identity, stamp the historical
refresh version and reconstruct eligible surface materials through WMOBuilder.

## Non-goals

- Traverse scene Nodes or own Mesh/MultiMesh attachment and lifetime.
- Select WMO cache paths, poll ResourceLoader or schedule render build jobs.
- Change WMOBuilder shaders, textures, blend rules or cache serialization.
- Share an abstraction with the behaviorally different M2 finalizer.

## Context and boundaries

```mermaid
flowchart LR
    Loader[StreamingWorldLoader traversal/build step] -->|Mesh plus extracted directory| Finalizer[WmoRuntimeMeshFinalizer]
    Finalizer -->|material definition plus compact texture paths| Builder[WMOBuilder material boundary]
    Builder -->|rebuilt Material| Finalizer
    Finalizer -->|same Mesh identity| Loader
```

The loader owns scene traversal and composition. The finalizer owns only the
in-place Resource operation and depends on an injected WMO material builder.

## Public API

| Symbol | Kind | Purpose | Thread/lifetime | Errors |
|---|---|---|---|---|
| `finalize_mesh(mesh, extracted_directory)` | Command/query | Stamp and refresh a stale Mesh in place | Renderer main thread; stateless between calls | Null returns null; unsupported Mesh returns exact identity |
| `rebuild_cached_material(material, extracted_directory)` | Query/boundary | Reconstruct one metadata-bearing cached WMO Material | Renderer main thread; borrowed input | Null/unmarked/missing builder returns null |

## Inputs and outputs

| Direction | Contract/data | Producer | Consumer | Ownership | Thread/lifetime |
|---|---|---|---|---|---|
| Input | `Mesh` and refresh metadata | Cached WMO scene/render group | Finalizer | Borrowed Resource | Call duration; identity retained |
| Input | Extracted content directory | Loader configuration | WMOBuilder | Borrowed String value | Call duration |
| Input | Texture paths, WMO flags/shader/blend and cached colors | Surface Material metadata/parameters | Finalizer | Borrowed values | One surface rebuild |
| Output | Compact texture-path array and material definition | Finalizer | WMOBuilder | Detached values | One builder call |
| Output | Rebuilt Material | WMOBuilder | ArrayMesh surface | Surface adopts exact Resource | Mesh lifetime |
| Output | Exact input Mesh | Finalizer | Loader traversal/build step | Caller retains ownership | Existing cache/scene lifetime |

## Data flow

```mermaid
flowchart TD
    Mesh[Borrowed Mesh] --> Null{Null?}
    Null -->|yes| ReturnNull[Return null]
    Null -->|no| Current{Refresh version at least 10?}
    Current -->|yes| ReturnSame[Return exact Mesh]
    Current -->|no| Stamp[Stamp version 10]
    Stamp --> Array{ArrayMesh?}
    Array -->|no| ReturnSame
    Array -->|yes| Surface[Iterate surfaces]
    Surface --> Eligible{Material has texture0 metadata?}
    Eligible -->|no| Keep[Keep exact Material]
    Eligible -->|yes| Definition[Compact paths and copy metadata/colors]
    Definition --> Builder[WMOBuilder build material]
    Builder --> Result{Non-null result?}
    Result -->|yes| Adopt[Replace surface Material]
    Result -->|no| Keep
    Keep --> Surface
    Adopt --> Surface
    Surface -->|done| ReturnSame
```

## Lifecycle/state

```mermaid
stateDiagram-v2
    [*] --> Stale: missing/version below 10
    [*] --> Current: version at least 10
    Stale --> Current: stamp before optional surface refresh
    Current --> Current: subsequent calls are identity-only
```

The version stamp is intentionally applied before type/material eligibility, as
in the extracted loader behavior. The finalizer retains no Mesh or Material.

## Main sequence

```mermaid
sequenceDiagram
    participant Loader as StreamingWorldLoader
    participant Finalizer as WmoRuntimeMeshFinalizer
    participant Mesh as ArrayMesh
    participant Builder as WMOBuilder
    Loader->>Finalizer: finalize_mesh(mesh, extracted_directory)
    Finalizer->>Mesh: read/stamp refresh metadata
    loop each stale ArrayMesh surface
        Finalizer->>Mesh: surface_get_material(index)
        alt cached WMO metadata exists
            Finalizer->>Builder: _build_material(definition, compact paths, directory)
            Builder-->>Finalizer: rebuilt Material or null
            Finalizer->>Mesh: surface_set_material when non-null
        end
    end
    Finalizer-->>Loader: exact Mesh identity
```

## Dependency diagram

```mermaid
flowchart TB
    Loader[StreamingWorldLoader] --> Finalizer[WmoRuntimeMeshFinalizer]
    Finalizer --> Engine[Mesh / ArrayMesh / Material]
    Finalizer --> Builder[Injected WMO material builder]
    Finalizer -. no dependency .-> Nodes[Node traversal/lifetime]
    Finalizer -. no dependency .-> RL[ResourceLoader]
    Finalizer -. no dependency .-> Queue[Build queue/scheduler]
```

## Ownership, threading and resources

- The renderer main thread serializes Mesh metadata and surface mutation.
- The caller owns Mesh identity, scene traversal, attachment and destruction.
- ArrayMesh surfaces adopt only non-null builder results; otherwise the exact
  cached Material remains attached.
- The service retains no Resource, Node, RID, file, queue or per-path state.

## Errors, cancellation and recovery

| Failure/state | Detection | Behavior | Diagnostic | Recovery |
|---|---|---|---|---|
| Null Mesh | Guard | Return null | Synthetic contract | Correct caller input |
| Current Mesh | Version metadata | Return exact identity, no builder call | Identity/version contract | Version bump makes it stale |
| Unsupported Mesh subtype | Type check after stamp | Return exact identity | PrimitiveMesh contract | No surface work required |
| Null/unmarked Material | Metadata guard | Preserve exact surface value | Surface contract | Rebuild cache with metadata |
| Missing builder/null result | Boundary guard/result | Preserve exact Material | Synthetic contract | Correct composition/retry after version bump |
| Shutdown | Loader lifecycle | No retained work to cancel | Shutdown suite | New loader composes a new service |

## Configuration and capabilities

Refresh version `10` and metadata key `wow_wmo_material_refresh_version` are the
existing runtime compatibility boundary. No project setting, profile, permit or
feature flag is introduced.

## Persistence, cache and migration

The module writes only the existing runtime Mesh metadata stamp and serializes
nothing. It does not change WMO scene/render cache formats or trigger rebakes.
A future material-rule change must deliberately bump the refresh version.

## Diagnostics and observability

The finalizer emits no logs and allocates no metrics. Existing `wmobuild` queue
metrics and loader diagnostics remain the operational correlation surface.

## Verification

- `verify_wmo_runtime_mesh_finalizer.gd`: null/current/non-ArrayMesh identity,
  version stamp, null/unmarked surface retention, compact path indices,
  flags/shader/blend/default and shader colors, exact builder adoption,
  missing-builder behavior, source ownership and 1,000 current calls under one second.
- Adjacent WMO queue/cache/finalizer, shutdown, material and baseline regressions
  protect orchestration and visible output.
- Fidelity evidence is exact behavior-preserving extraction; no private asset or
  original-client visual-parity claim is added.

## Extension points

- Asset-backed WMO fixtures may compare reconstructed surface parameters without
  changing the service contract.
- A deliberate material refresh change may bump the owned version with old/new
  fixtures and paired visual evidence.

## Capability status

| Capability | Status | Evidence | Gap/next step |
|---|---|---|---|
| Runtime refresh admission | Implemented extraction | Identity/version/type contracts | Serialized cache fixture pending |
| Cached material definition reconstruction | Implemented extraction | Path/metadata/color contracts | Asset-backed visual comparison pending |
| Scene traversal/materialization | Loader-owned | Existing WMO regressions | Further safe extraction pending |

## Known gaps and risks

- Surface mutation and WMOBuilder material construction remain synchronous
  main-thread work.
- No proprietary WMO corpus, long leak run, GPU timing, traversal p95/p99 or
  paired build-12340 visual capture is included.

## Source map

| Path | Responsibility |
|---|---|
| `src/render/wmo/wmo_runtime_mesh_finalizer.gd` | Refresh admission, surface iteration and material definition reconstruction |
| `addons/mpq_extractor/loaders/wmo_builder.gd` | WMO shader/material construction semantics |
| `src/scenes/streaming/streaming_world_loader.gd` | Composition, Node traversal, build jobs and lifetime |
| `src/tools/verify_wmo_runtime_mesh_finalizer.gd` | Identity/version/material/source/timing regression |

## Related decisions and references

- [`wmo-render-build-queue.md`](wmo-render-build-queue.md)
- [`wmo-render-resource-finalizer.md`](wmo-render-resource-finalizer.md)
- [`wmo-scene-resource-finalizer.md`](wmo-scene-resource-finalizer.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)