# WMO Render Resource Cache State

## Metadata

| Field | Value |
|---|---|
| Status | Implemented |
| Target/work package | M03 / `M03-RND-WMO-RENDER-RESOURCE-CACHE-001` |
| Owners | Validated lightweight-WMO render Resources, negative cache and pending request paths |
| Last verified | Worktree `work/sindo-main-codex/m03-wmo-render-resource-cache`, 2026-07-17 |
| Profiles/capabilities | Lightweight WMO render-cache path; profile-independent |

## Purpose

Own the mutually exclusive cached, missing and pending states for normalized
lightweight-WMO render paths outside the monolithic streamer. The state holder
accepts only caller-validated `Resource` references and records cache paths for
threaded requests whose I/O lifecycle remains in `StreamingWorldLoader`.

## Non-goals

- Normalize WMO paths or construct `.res` cache paths.
- Call `ResourceLoader`, inspect files or validate script/format versions.
- Own WMO cached scenes, live prototypes, placements, build jobs or engine Nodes.
- Change fallback order, retry timing, quality profiles or visible output.
- Persist, migrate or build WMO caches.

## Context and boundaries

```mermaid
flowchart LR
    Placement[Normalized WMO render lookup] --> Loader[StreamingWorldLoader]
    Loader --> State[WmoRenderResourceCacheState]
    State -->|cached Resource| Loader
    Loader -->|cache path| ResourceLoader[Godot ResourceLoader]
    ResourceLoader -->|status and loaded Resource| Loader
    Loader --> Validate[Script and FORMAT_VERSION validation]
    Validate -->|accepted Resource or missing| State
    Loader --> Fallback[Cached scene or live-prototype fallback]
```

The module may retain validated `Resource` references and copied path Strings.
It has no FileAccess, ResourceLoader, Node, RID, worker, mutex, gameplay, network
or editor dependency. Cache validation stays at the I/O boundary in the loader.

## Public API

| Symbol | Kind | Purpose | Thread/lifetime | Errors |
|---|---|---|---|---|
| `resource_for(path)` | Query | Borrow validated cached Resource | Renderer main thread; until full clear | Empty/unknown returns null |
| `contains_resource(path)` | Query | Test accepted cache state | Renderer main thread | Empty returns false |
| `is_missing(path)` | Query | Test negative cache state | Renderer main thread | Empty returns false |
| `has_request(path)` | Query | Test pending threaded-request state | Renderer main thread | Empty returns false |
| `remember_request(path, cache_path)` | Command/query | Record one loader-started request | Renderer main thread; until terminal/reset | Invalid or occupied state returns false |
| `request_paths_snapshot()` | Query | Copy pending normalized/cache-path mapping | Poll or shutdown drain | Detached Dictionary |
| `complete_request_with_resource(path, resource)` | Command/query | Remove pending request and adopt caller-validated Resource | Terminal loader poll | Unknown/null returns false |
| `complete_request_as_missing(path)` | Command/query | Remove pending request and adopt negative state | Terminal loader poll | Unknown returns false |
| `clear_transient_state()` | Command | Clear pending and missing while retaining accepted Resources | Map reset/request drain | Idempotent |
| `clear_all()` | Command | Release Resources, pending and missing | Final runtime cache release | Idempotent |
| `pending_request_count()` | Query | Preserve renderer queue metric contribution | Renderer diagnostics | None |
| `diagnostic_snapshot()` | Query | Return sorted detached scalar keys | Tests/diagnostics | Never exposes Resources |

## Inputs and outputs

| Direction | Contract/data | Producer | Consumer | Ownership | Thread/lifetime |
|---|---|---|---|---|---|
| Input | Normalized relative WMO path | Placement resolver through loader | Cache state | Copied String | Map/cache lifetime |
| Input | `.res` cache path after accepted threaded-request result | Loader | Pending state | Copied String | Until terminal/reset |
| Input | Script/version-validated WMO Resource | Loader validation adapter | Resource cache | Strong reference | Until full clear |
| Output | Borrowed validated Resource | Cache state | Loader render-root/build adapters | State retains reference | Lookup/build start |
| Output | Detached pending-path snapshot | Cache state | Loader ResourceLoader polling/shutdown | Caller-owned Dictionary | One drain pass |
| Output | Sorted scalar diagnostic keys | Cache state | Verifier/future metrics | Caller-owned values | Snapshot lifetime |

## Data flow

```mermaid
flowchart TD
    Lookup[Lookup normalized path] --> Cached{Cached?}
    Cached -->|yes| Return[Return validated Resource]
    Cached -->|no| Blocked{Missing or pending?}
    Blocked -->|yes| Null[Return null; loader waits/falls back]
    Blocked -->|no| Start[Loader starts threaded request]
    Start --> Remember[remember_request]
    Remember --> Poll[Loader polls detached request snapshot]
    Poll --> Terminal{Loaded or failed?}
    Terminal -->|no| Poll
    Terminal -->|failed| Missing[complete as missing]
    Terminal -->|loaded| Validate[Loader validates script/version]
    Validate -->|valid| Adopt[complete with Resource]
    Validate -->|invalid| Missing
```

## Lifecycle/state

Each normalized path is `Absent`, `Pending`, `Cached` or `Missing`. Valid request
completion leaves exactly one terminal state. Transient clear moves `Pending` and
`Missing` to `Absent` but retains `Cached`; full clear moves every state to
`Absent` and releases retained Resources.

```mermaid
stateDiagram-v2
    [*] --> Absent
    Absent --> Pending: remember valid request
    Pending --> Cached: validated Resource completion
    Pending --> Missing: load/validation failure
    Pending --> Absent: clear transient/full
    Missing --> Absent: clear transient/full
    Cached --> Absent: full clear
```

## Main sequence

```mermaid
sequenceDiagram
    participant Loader as StreamingWorldLoader
    participant State as WmoRenderResourceCacheState
    participant RL as ResourceLoader
    Loader->>State: cached/missing/pending queries
    Loader->>RL: exists + load_threaded_request(cache path)
    Loader->>State: remember_request(normalized, cache path)
    loop renderer tick
        Loader->>State: request_paths_snapshot()
        Loader->>RL: load_threaded_get_status(cache path)
    end
    alt load failed
        Loader->>State: complete_request_as_missing(normalized)
    else loaded
        Loader->>RL: load_threaded_get(cache path)
        Loader->>Loader: validate script and FORMAT_VERSION
        Loader->>State: complete with Resource or as missing
    end
```

## Ownership, threading and resources

- The state owns three Dictionaries and strong references to accepted Resources.
- The loader owns normalization, cache paths, ResourceLoader calls and validation.
- All mutation is serialized by the renderer main-thread lookup/drain lifecycle.
- No mutex or callback is needed; detached request snapshots permit safe removal.
- The loader/build queue borrow Resources without transferring ownership.

## Errors, cancellation and recovery

| Failure/state | Detection | Behavior | Diagnostic | Recovery |
|---|---|---|---|---|
| Empty path/cache path | Request guard | Reject unchanged | Contract verifier | Repair caller input |
| Duplicate or occupied path | State membership | Reject request unchanged | Contract/source verifier | Await terminal/reset |
| Threaded load failed | Loader status | Complete as missing | Existing renderer metrics | Transient reset permits retry |
| Wrong script/old format | Loader validation | Complete as missing | Cache-version source gate | Rebuild cache, then reset |
| Shutdown while pending | Loader drains ResourceLoader snapshot | Clear transient afterward | Shutdown verifier | Next runtime starts absent |
| Final cache release | Loader shutdown lifecycle | Full clear releases Resources | Shutdown verifier | Recreated with loader |

## Configuration and capabilities

The module adds no setting or profile branch. `wmo_render_cache_dir`, resource
format version, request scheduling and WMO build budgets remain loader-owned.

## Persistence, cache and migration

The state is runtime-only and serializes nothing. `WMOStreamingResource` script
identity and `FORMAT_VERSION` validation remain unchanged in the loader; no cache
migration or rebuild is introduced by this extraction.

## Diagnostics and observability

`pending_request_count` preserves the existing `wmobuild` metric contribution.
Diagnostics expose only sorted normalized-path keys for cached/missing/pending
states; Resource references and cache file paths are not exposed. No logs emit.

## Verification

- `verify_wmo_render_resource_cache_state.gd`: invalid input, detached requests,
  successful/missing terminal transitions, exclusivity, partial/full reset,
  sorted diagnostics, ownership/source boundary and bounded timing.
- `verify_render_runtime_cache_shutdown.gd`: full release of accepted Resources
  and negative state through the loader lifecycle.
- WMO queue/planner/registry/resolver and surrounding renderer regressions verify
  unchanged fallback/build behavior. This package makes no visual parity claim.

## Extension points

- Cached WMO scene request state is a separate typed module because its size
  limit, PackedScene validation and missing-file behavior differ.
- A later loader I/O adapter may consume the detached request snapshot while
  preserving this state contract and cache-version boundary.

## Capability status

| Capability | Status | Evidence | Gap/next step |
|---|---|---|---|
| Lightweight WMO render Resource state | Implemented extraction | Lifecycle/source/timing and shutdown verifiers | Asset-backed traversal/leak evidence pending |
| Cache script/version validation | Preserved in loader | Source boundary and WMO regressions | Dedicated corrupt-cache fixture could follow |
| Cached WMO scene state | Implemented extraction | Scene-cache lifecycle/source/timing verifier | Asset-backed traversal/leak evidence pending |
| WMO materialization | Partial/loader-owned | Queue/planner regressions | Further safe extraction |

## Known gaps and risks

- Strong Resource references live until final cache release, matching prior state.
- Missing cache files remain unrecorded for render Resources, so lookup can retry;
  this intentionally differs from the cached-scene path.
- No proprietary WMO corpus, corrupt-version fixture, leak run, traversal p95/p99
  or paired original-client capture is included.

## Source map

| Path | Responsibility |
|---|---|
| `src/render/wmo/wmo_render_resource_cache_state.gd` | Resource/missing/request state and resets |
| `src/scenes/streaming/streaming_world_loader.gd` | Normalize, request, poll, validate, fallback and shutdown I/O |
| `src/tools/verify_wmo_render_resource_cache_state.gd` | State, boundary and timing regression |
| `src/tools/verify_render_runtime_cache_shutdown.gd` | Loader final Resource ownership regression |

## Related decisions and references

- [`wmo-render-build-queue.md`](wmo-render-build-queue.md)
- [`wmo-scene-resource-cache-state.md`](wmo-scene-resource-cache-state.md)
- [`wmo-placement-resolver.md`](wmo-placement-resolver.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)
