Blacksite/docs/editor/brp.md

# Bevy Remote Protocol (BRP)

The editor enables Bevy’s built-in **Remote Plugin** over HTTP for automation, CI, and future tooling interop. BRP is **editor-only** — the shipped `game` binary does not expose a port.

## Enablement

`BrpPlugin` in `crates/editor/src/ext/brp.rs` adds:

- `RemotePlugin` — core remote API
- `RemoteHttpPlugin` — HTTP transport

Launch the editor with dev features as usual:

```bash
cargo run -p editor --features dev
```

Default HTTP endpoint follows Bevy 0.19 remote defaults (port **15702**, routes under `/remote/`).

## Authoring-only mutation policy

**BRP and automation must mutate authoring components only** — the same allowlist used on scene save in `scene_io.rs`. Hydration rebuilds runtime ECS (`Mesh3d`, Bevy lights, physics, `WorldAssetRoot`, etc.) on the next frame.

| Allowed (examples) | Forbidden on level objects |
|--------------------|----------------------------|
| `Transform`, `Name`, `ActorKind` | `PointLight`, `SpotLight`, `DirectionalLight` |
| `Primitive`, `StaticMeshRenderer`, `SkinnedMeshRenderer`, `MaterialDesc`, `MaterialOverride`, `LightDesc` | `Mesh3d`, `MeshMaterial3d`, `RigidBody`, `Collider` |
| `ModelRef`, `RigidBodyDesc`, `ColliderDesc`, legacy `PhysicsBody`, gameplay markers | `WorldAssetRoot`, generated static/skinned roots, internal visibility types |
| `PostProcessVolumeDesc` | Runtime post-process components on cameras |

Prefer:

1. Editing `LightDesc` instead of `SpotLight` / `DirectionalLight`
2. Editing `MaterialDesc` instead of `StandardMaterial` handles
3. Editing `StaticMeshRenderer` instead of child `Mesh3d` entities
4. Editing `SkinnedMeshRenderer` instead of its hydrated joint/mesh hierarchy
5. Editing `ColliderDesc` / `RigidBodyDesc` instead of runtime Avian components
5. Version-controlled `assets/levels/*.scn.ron` for durable changes

See [ADR 0009 — Authoring vs hydrated](../adr/0009-authoring-vs-hydrated.md).

## Example flows

### List entities

```bash
curl -s http://127.0.0.1:15702/remote/world/entities | head
```

### Get entity components

```bash
curl -s -X POST http://127.0.0.1:15702/remote/world/get \
  -H 'Content-Type: application/json' \
  -d '{"entity":4294967296,"components":["bevy_transform::Transform"]}'
```

### Mutate authoring transform (automation smoke)

```bash
curl -s -X POST http://127.0.0.1:15702/remote/world/mutate \
  -H 'Content-Type: application/json' \
  -d '{"entity":4294967296,"component":"bevy_transform::Transform","value":{"translation":[0,2,0]}}'
```

Replace `entity` with a live id from the list call while the editor is running.

### Mutate `LightDesc` (not runtime lights)

```bash
curl -s -X POST http://127.0.0.1:15702/remote/world/mutate \
  -H 'Content-Type: application/json' \
  -d '{"entity":ENTITY_ID,"component":"shared::components::LightDesc","value":{...}}'
```

Hydration applies the change to viewport lighting after the next update.

### Mutate `PostProcessVolumeDesc`

```bash
curl -s -X POST http://127.0.0.1:15702/remote/world/mutate \
  -H 'Content-Type: application/json' \
  -d '{"entity":ENTITY_ID,"component":"shared::components::PostProcessVolumeDesc","value":{...}}'
```

Overrides use `None` = inherit project; `Some(v)` = local override per field.

## Editor command palette bridge

Registered commands in `extensibility.rs` are invokable via **Ctrl+P** and `PendingEditorCommands`:

| Command | Action |
|---------|--------|
| `play.toggle` | Edit / Play |
| `play.toggle_pause` | Pause / resume sim in Play |
| `play.toggle_possession` | Possess / eject (Play only) |
| `scene.reset_lighting` | Remove all authored `LightDesc`; use project sun/ambient |
| `selection.group` | Spawn empty group; reparent selection |
| `selection.focus` | Frame editor camera on selection (same as **F**) |
| `rendering.create_volume` | Spawn post-process volume at editor camera |
| `rendering.select_volumes_at_camera` | Select highest-priority volume at camera |
| `rendering.focus_active_volumes` | Select + frame volumes at camera |

External automation can enqueue the same names through the editor command queue when integrated.

## CI / headless validation

Validate committed levels and prefab dependency graphs without the editor UI:

```bash
cargo validate-levels
# JSON for CI, packaging, or external tools
cargo validate-levels --json
```

This runs the shared `scene::validate_project` report used by the editor Diagnostics window. It
validates authored levels and recursive prefab/composition graphs, emits an owner-attributed
dependency manifest, reports blocking content references, and exits nonzero on errors.
`--project <path>` validates another project root. The graph pass validates link paths, stable actor
identity, cycles, anchors, and override payloads without starting the editor. The same report scans
project settings and asset roots, registry/import dependencies, generated mesh manifests, material
and shader documents, post effects, brush geometry, collider dimensions, Git LFS hydration, and
platform requirements. Validation and packaging share one runtime-inclusion policy: hidden/editor
trees, source formats such as PSD/Blend, symlinks, and unreadable traversal are blocking when a
runtime dependency reaches them. `asset.git_lfs_object_missing` is blocking; run `git lfs pull` in
the project checkout and rerun validation before building a package.

```bash
cargo test -p shared
cargo test -p scene
cargo check -p editor --features dev
```

## Safety

- Run BRP only in trusted local dev environments.
- Do not enable `BrpPlugin` in production game builds.
- Scene files remain the source of truth; prefer version-controlled `assets/levels/*.scn.ron` over live mutation for durable changes.

## Related

- [Editor architecture](architecture.md)
- [Debt audit checklist](debt-audit.md)
- [Mission — BRP-aligned tooling](../mission.md)
- [Release notes](release-notes.md)