# M2 Build Dispatch Planner

## Metadata

| Field | Value |
|---|---|
| Status | Implemented extraction |
| Target/work package | M03 / `M03-RND-M2-BUILD-DISPATCH-PLANNER-001` |
| Owners | Pure M2 resource-state to build-action decision |
| Last verified | Worktree `work/sindo-main-codex/m03-m2-build-dispatch-planner`, 2026-07-18 |
| Profiles/capabilities | Existing static MultiMesh and animated-instance build paths |

## Purpose

Select one M2 build action after the loader observes animation/static resource
state. The planner makes wait priority, materializer selection and the historical
missing-model serial transition explicit without owning resources or engine work.

## Non-goals

- Locate, request, load, cache or validate M2 resources.
- Size batches, own build jobs/queues or consume renderer permits.
- Create, attach or free Nodes, Meshes, MultiMeshes or animated instances.
- Change transforms, ordering, render settings, profiles or visible output.
- Add spatial-cell batching or M2 format/fidelity behavior.

## Context and boundaries

```mermaid
flowchart LR
    Loader[StreamingWorldLoader resource observations] --> Planner[M2BuildDispatchPlanner]
    Planner --> Action[Detached action and transition plan]
    Action --> Loader
    Loader --> Queue[M2BuildQueue rotate/progress]
    Loader --> Animated[M2AnimatedInstanceMaterializer]
    Loader --> Static[M2StaticBatchMaterializer]
    Loader --> Budget[RenderBudgetScheduler]
```

The planner depends only on `RefCounted`, scalar values, `StringName` constants
and a fresh Dictionary. ResourceLoader, caches, Nodes, Meshes, RenderingServer,
SceneTree, files, workers, mutexes, gameplay, network and Editor APIs are forbidden.

## Public API

| Symbol | Kind | Purpose | Thread/lifetime | Errors |
|---|---|---|---|---|
| `ACTION_WAIT_FOR_ANIMATION` | Constant | Pending animation request blocks all other actions | Immutable | None |
| `ACTION_MATERIALIZE_ANIMATED` | Constant | Build the selected slice from animated prototype | Immutable | None |
| `ACTION_WAIT_FOR_STATIC_MESH` | Constant | Static resource is unresolved and queue must rotate | Immutable | None |
| `ACTION_MATERIALIZE_STATIC` | Constant | Build the selected slice from prepared static Mesh | Immutable | None |
| `ACTION_ADVANCE_WITHOUT_MATERIALIZATION` | Constant | Empty or terminally missing slice advances without a Node | Immutable | None |
| `plan_step(batch_count, resource_snapshot)` | Pure query | Return action, queue-rotation and serial-transition values | Any thread; call-local result | Null snapshot waits for static Mesh; non-positive count advances |

## Inputs and outputs

| Direction | Contract/data | Producer | Consumer | Ownership | Thread/lifetime |
|---|---|---|---|---|---|
| Input | Planned batch count | `M2BuildBatchPlanner` through loader | Dispatch planner | Integer copy | One call |
| Input | Typed animated/static availability, pending and missing observations | Loader / `M2BuildResourceSnapshot` | Dispatch planner | Borrowed snapshot; engine references are not read | One call |
| Output | Action | Dispatch planner | Loader materializer/wait branch | Immutable StringName | One operation |
| Output | `rotate_queue` | Dispatch planner | Loader queue adapter | Detached boolean | One operation |
| Output | `increment_batch_serial` | Dispatch planner | Loader progress adapter | Detached boolean | One operation |

The output Dictionary is newly allocated and caller-owned. The planner retains
no state, resource or engine-object reference.

## Data flow

```mermaid
flowchart TD
    Input[Observed state] --> AnimationPending{Animation request pending?}
    AnimationPending -->|yes| WaitAnimation[Wait animation; rotate]
    AnimationPending -->|no| Positive{Batch count positive?}
    Positive -->|no| AdvanceEmpty[Advance; keep serial]
    Positive -->|yes| Animated{Animated prototype?}
    Animated -->|yes| BuildAnimated[Materialize animated; increment serial]
    Animated -->|no| StaticReady{Static Mesh ready?}
    StaticReady -->|yes| BuildStatic[Materialize static; increment serial]
    StaticReady -->|no| Missing{Model terminally missing?}
    Missing -->|yes| AdvanceMissing[Advance without Node; increment serial]
    Missing -->|no| WaitStatic[Wait static Mesh; rotate]
```

## Lifecycle/state

```mermaid
stateDiagram-v2
    [*] --> Observe
    Observe --> Waiting: animation/static unresolved
    Observe --> Materializing: animated/static resource ready
    Observe --> Advancing: empty or terminally missing batch
    Waiting --> [*]: detached wait plan
    Materializing --> [*]: detached materialization plan
    Advancing --> [*]: detached advance plan
```

The planner itself is stateless. Queue rotation, cursor adoption, cancellation,
map reset and shutdown remain external lifecycle transitions.

## Main sequence

```mermaid
sequenceDiagram
    participant L as StreamingWorldLoader
    participant B as M2BuildBatchPlanner
    participant D as M2BuildDispatchPlanner
    participant Q as M2BuildQueue
    participant M as M2 materializer
    participant S as RenderBudgetScheduler
    L->>L: observe animation request/prototype
    alt animation not pending
        L->>B: plan_batch
        L->>L: lookup/request static Mesh when required
    end
    L->>D: plan_step(batch count, resource snapshot)
    D-->>L: action, rotate flag, serial flag
    alt wait action
        L->>Q: rotate_front
    else materialize action
        L->>M: materialize selected slice
        L->>Q: adopt progress and serial
    else advance action
        L->>Q: adopt progress and optional serial
    end
    L->>S: consume one M2_BUILD permit
```

## Dependency diagram

```mermaid
flowchart TB
    Loader[StreamingWorldLoader] --> Dispatch[M2BuildDispatchPlanner]
    Loader --> Batch[M2BuildBatchPlanner]
    Loader --> Queue[M2BuildQueue]
    Loader --> Caches[M2 cache/pipeline state]
    Loader --> Materializers[M2 materializers]
    Dispatch --> Snapshot[M2BuildResourceSnapshot accessors]
    Dispatch --> Values[Integers + booleans + StringName]
    Dispatch -. no dependency .-> Engine[Node / Mesh / ResourceLoader]
    Dispatch -. no dependency .-> State[Queue / cache / scheduler state]
```

## Ownership, threading and resources

- Planner owns call-local comparisons and the returned Dictionary only.
- `M2BuildResourceSnapshot` owns the typed call-local observation contract;
  dispatch reads availability/pending/missing accessors but no engine references.
- Loader owns resource lookup/request order, action execution and permit use.
- `M2BuildQueue` owns pending jobs, FIFO keys and progress cursors.
- Materializers own main-thread scene construction under loader-owned roots.
- Pure calls are thread-safe; the current loader adapter calls on main thread.

## Errors, cancellation and recovery

| Failure/state | Detection | Behavior | Diagnostic | Recovery |
|---|---|---|---|---|
| Animation request pending | Boolean observation | Wait wins even if other flags are true | Priority fixture | Retry when queue returns front |
| Non-positive batch | Count comparison | Advance without serial increment | Zero/negative fixtures | Next group/cursor operation |
| Static Mesh unresolved | No Mesh and not missing | Rotate without serial increment | Retry fixture | Loader request/cache completes |
| Static model missing | Terminal missing flag | Advance without Node and increment serial | Missing fixture | Later group continues |
| Contradictory static ready/missing | Both true | Ready Mesh wins | Priority fixture | Loader normally prevents contradiction |
| Tile cancellation/root invalid | Outside planner | Loader cancels before dispatch | Queue/shutdown regressions | Eligible tile may requeue |

## Configuration and capabilities

The planner adds no setting. Existing animated/static batch limits, animation
enable flag, visibility/shadow settings and `M2_BUILD` permits remain external.

## Persistence, cache and migration

No state is serialized. No ADT/M2 cache format or version changes; no rebake or
migration is required.

## Diagnostics and observability

The planner emits no logs. Its verifier reports the action matrix, source
boundaries and bounded 20,000-call timing. Existing loader queue/hitch metrics
remain unchanged.

## Verification

- `verify_m2_build_dispatch_planner.gd` covers wait priority, zero/negative
  counts, animated/static priority, unresolved retry, terminal missing, detached
  results, loader/dependency boundaries and bounded timing.
- Queue, batch planner, materializers, caches, shutdown, facade, internal-access
  and checkpoint tests protect adjacent behavior.
- Fidelity evidence is exact branch/transition extraction only. No private asset
  or original-client visual comparison is claimed.

## Extension points

A later package may move resource observation/request execution behind a service
that produces `M2BuildResourceSnapshot`. Generic callbacks, signals and a shared
state-machine framework remain intentionally excluded.

## Capability status

| Capability | Status | Evidence | Gap/next step |
|---|---|---|---|
| M2 build action selection | Implemented extraction | Priority/matrix/source/timing verifier | Asset-backed traversal pending |
| Resource observation and requests | Loader-owned | Cache/pipeline regressions | Typed orchestration extraction pending |
| Queue/cursor state | Implemented separately | M2 build queue verifier | Asset-backed traversal pending |
| Materialization | Implemented separately | Static/animated materializer verifiers | GPU/p95/p99 evidence pending |

## Known gaps and risks

- Loader still performs synchronous/native prototype attempts and static request I/O.
- Synthetic timing does not measure ResourceLoader, Node or GPU work.
- Private traversal, leak, visual and p95/p99 evidence remains unavailable.

## Source map

| Path | Responsibility |
|---|---|
| `src/render/m2/m2_build_dispatch_planner.gd` | Pure action priority and transition plan |
| `src/render/m2/m2_build_resource_snapshot.gd` | Typed per-step resource observation contract |
| `src/scenes/streaming/streaming_world_loader.gd` | Resource observation, action execution, permits and engine lifetime |
| `src/render/m2/m2_build_batch_planner.gd` | Batch count and cursor plan |
| `src/render/m2/m2_build_queue.gd` | Pending jobs, FIFO and cursor ownership |
| `src/tools/verify_m2_build_dispatch_planner.gd` | Matrix, boundary and timing regression |

## Related decisions and references

- [`m2-build-batch-planner.md`](m2-build-batch-planner.md)
- [`m2-build-resource-snapshot.md`](m2-build-resource-snapshot.md)
- [`m2-build-queue.md`](m2-build-queue.md)
- [`m2-static-batch-materializer.md`](m2-static-batch-materializer.md)
- [`m2-animated-instance-materializer.md`](m2-animated-instance-materializer.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)