# PICO MCP Extensions

PICO XR feature construction APIs for Unity MCP agents. Idempotent, non-destructive, ambiguity-aware.

## Overview

This Unity package exposes PICO XR building blocks as MCP (Model Context Protocol) tools, enabling AI agents (e.g. Unity AI Assistant) to programmatically configure XR scenes for PICO devices. It is designed to be used together with the **PICO Unity Integration SDK 6.0.x** and aligns its dependency baseline with that SDK (XR Interaction Toolkit **3.x**).

**Package name:** `com.bytedance.pico.mcp-extensions`  
**Version:** 0.0.6  
**Unity:** 6000.0+  
**Author:** ByteDance PICO

## Requirements

| Dependency | Minimum Version |
|---|---|
| com.unity.xr.core-utils | 2.3.0 |
| com.unity.xr.interaction.toolkit | 3.4.0 |
| com.unity.inputsystem | 1.18.0 |
| Unity AI Assistant (Unity.AI.MCP.Editor) | 2.x |
| com.bytedance.pico.xr | 6.0.0 |

## Features

Seven XR building blocks, each with Enable / Disable / Status semantics:

| Block | Description |
|---|---|
| **VST** | Video See-Through (passthrough) - configures camera for transparent background and adds `PXR_CameraEffectBlock` |
| **Controller** | Mounts PICO controller visual models on Left/Right hand anchors |
| **Locomotion** | Enables XRI locomotion subtree with fine-grained presets (Move, Turn, Teleportation, GrabMove, Climb, Gravity, Jump) |
| **Spatial Mesh** | Configures `PXR_SpatialMeshManager` with auto-detected MeshPrefab (depends on VST) |
| **Plane Detection** | Configures PICO SensePack plane detection via a bundled `PXR_PlaneDetectionManager` driver (depends on VST; PICO-native runtime only) |
| **Hand** | Enables PICO hand tracking (virtual hands) plus an XRI hand-interactor rig so a pinch can drive grab |
| **Grab** | Object pick-up & drag; ensures the scene `XRInteractionManager` broker and can upgrade a target object into a grabbable |

Additionally, a **Package** tool manages Unity packages and samples (install / remove / update / import samples / query resolvable version).

### Dual runtime support (PICO-native + OpenXR)

The building blocks compile and configure correctly under **both** PICO XR runtimes:

- **PICO-native runtime** (`ENABLE_PICO_XR_SDK`)
- **OpenXR runtime** (`ENABLE_PICO_OPENXR_SDK`) — VST enables the PICO `PassthroughFeature`; Spatial Mesh forces MultiPass rendering and enables the `PICOSpatialMesh` feature; Hand enables the Unity XR Hands models plus the PICO hand-tracking / hand-interaction OpenXR features.

> **Plane Detection is PICO-native only.** PICO ships no plane-detection OpenXR feature, so under the OpenXR runtime the plane provider is never created and the block is a no-op.

## Architecture

```
Editor/
  PXR_MCP_Common.cs        # Shared helpers: XR Origin lifecycle, module visibility
  PXR_MCP_Features.cs      # Building block implementations (VST, Controller, Locomotion, SpatialMesh, Plane, Hand, Grab)
  PXR_MCP_PackageOps.cs    # Package Manager operations (add, remove, samples)
  Tools/
    PXR_MCP_Tools.cs       # MCP tool surface ([McpTool] entry points)
    PXR_MCP_Result.cs      # Uniform result envelope for LLM consumption
```

**Layer 1 (Editor):** Plain C# static methods for building-block operations.  
**Layer 2 (Tools):** `[McpTool]`-annotated methods that wrap Layer 1 and return `PXR_MCP_Result` envelopes.

## MCP Tools

| Tool | Actions | Description |
|---|---|---|
| `pico_xr_vst` | Enable, Disable, Status | Manage Video See-Through |
| `pico_xr_controller` | Enable, Disable, Status | Manage PICO controller models |
| `pico_xr_locomotion` | Enable, Disable, Configure, Status | Manage locomotion with preset flags |
| `pico_xr_spatial_mesh` | Enable, Disable, Status | Manage spatial mesh (requires VST) |
| `pico_xr_plane` | Enable, Disable, Status | Manage PICO plane detection (requires VST; PICO-native runtime only) |
| `pico_xr_hand` | Enable, Disable, Status | Manage PICO hand tracking (virtual hands) |
| `pico_xr_grab` | Enable, Disable, Status, MakeGrabbable | Manage grab pick-up & drag; `make_grabbable` upgrades a target object |
| `pico_xr_package` | List, Info, Add, Remove, Update, ListSamples, ImportSample, Resolvable | Unity Package Manager operations; `resolvable` is a read-only query for the latest-compatible version |
| `pico_xr_status` | (none) | Aggregate snapshot of all blocks |

## Design Principles

- **Idempotent:** Re-running any operation with the same arguments is a safe no-op.
- **Non-destructive:** Never destroys or deactivates foreign (non-agent-owned) XR Origins.
- **Module isolation:** Enabling one block does not implicitly enable unrelated modules. Initial-create hides Controller and Locomotion so VST stays clean.
- **No hardcoded versions:** XRI paths and types are resolved dynamically via `PackageInfo` and reflection.
- **Undo-safe:** All scene modifications go through Unity's Undo system.

## Installation

Add this package to your Unity project via the Package Manager:

1. Open **Window > Package Manager**
2. Click **+** > **Add package from disk...** (or add to `Packages/manifest.json`)
3. Ensure XRI Starter Assets sample is imported (required for XR Origin prefab)

## License

Copyright (c) 2015-2022 PICO Technology Co., Ltd. All rights reserved. See [LICENSE.md](LICENSE.md) for details.