* fix: reduce per-frame GC allocations causing editor hitches (issue #577) Eliminate memory allocations that occurred every frame, which triggered garbage collection spikes (~28ms) approximately every second. Changes: - EditorStateCache: Skip BuildSnapshot() entirely when state unchanged (check BEFORE building). Increased poll interval from 0.25s to 1.0s. Cache DeepClone() results to avoid allocations on GetSnapshot(). - TransportCommandDispatcher: Early exit before lock/list allocation when Pending.Count == 0, eliminating per-frame allocations when idle. - StdioBridgeHost: Same early exit pattern for commandQueue. - MCPForUnityEditorWindow: Throttle OnEditorUpdate to 2-second intervals instead of every frame, preventing expensive socket checks 60+/sec. Fixes GitHub issue #577: High performance impact even when MCP server is off * fix: prevent multiple domain reloads when calling refresh_unity (issue #577) Root Cause: - send_command() had a hardcoded retry loop (min 6 attempts) on connection errors - Each retry resent the refresh_unity command, causing Unity to reload 6 times - retry_on_reload=False only controlled reload-state retries, not connection retries The Fix: 1. Unity C# (MCPForUnity/Editor): - Added --reinstall flag to uvx commands in dev mode - Ensures local development changes are picked up by uvx/Claude Code - Applies to all client configurators (Claude Code, Codex, etc.) 2. Python Server (Server/src): - Added max_attempts parameter to send_command() - Pass max_attempts=0 when retry_on_reload=False - Fixed type handling in refresh_unity.py (handle MCPResponse objects) - Added timeout to connection error recovery conditions - Recovery logic now returns success instead of error to prevent client retries Changes: - MCPForUnity/Editor: Added --reinstall to dev mode uvx commands - Server/refresh_unity.py: Fixed type handling, improved error recovery - Server/unity_connection.py: Added max_attempts param, disable retries when retry_on_reload=False Result: refresh_unity with compile=request now triggers only 1 domain reload instead of 6 Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com> * fix: UI and server stability improvements Unity Editor (C#): - Fix "Resuming..." stuck state when manually clicking End Session Clear ResumeStdioAfterReload and ResumeHttpAfterReload flags in OnConnectionToggleClicked and EndOrphanedSessionAsync to prevent UI from getting stuck showing "Resuming..." with disabled button - Remove unsupported --reinstall flag from all uvx command builders uvx does not support --reinstall and shows warning when used Use --no-cache --refresh instead for dev mode cache busting Python Server: - Add "aborted" to connection error patterns in refresh_unity Handle WinError 10053 (connection aborted) gracefully during Unity domain reload, treating it as expected behavior - Add WindowsSafeRotatingFileHandler to suppress log rotation errors Windows file locking prevents log rotation when file is open by another process; catch PermissionError to avoid noisy stack traces - Fix packaging: add py-modules = ["main"] to pyproject.toml setuptools.packages.find only discovers packages (directories with __init__.py), must explicitly list standalone module files Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com> * docs: improve refresh_unity connection loss handling documentation Add detailed comments and logging to clarify why connection loss during compile is treated as success (expected domain reload behavior, not failure). This addresses PR feedback about potentially masking real connection errors. The logic is intentional and correct: - Connection loss only treated as success when compile='request' - Domain reload causing disconnect is expected Unity behavior - Subsequent wait_for_ready loop validates Unity becomes ready - Prevents multiple domain reload loops (issue #577) Added logging for observability: - Info log when expected disconnect detected - Warning log for non-recoverable errors Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com> * fix: add missing logger import in refresh_unity Missing logger import causes NameError at runtime when connection loss handling paths are triggered (lines 82 and 91). Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com> * fix: address code review feedback on thread safety and semantics Addresses four issues raised in code review: 1. EditorStateCache.GetSnapshot() - Remove shared cached clone - Revert to always returning fresh DeepClone() to prevent mutation bugs - Main GC optimization remains: state-change detection prevents unnecessary _cached rebuilds (the expensive operation) - Removed _cachedClone and _cachedCloneSequence fields 2. refresh_unity.py - Fix blocking reason terminology mismatch - Changed "asset_refresh" to "asset_import" to match activityPhase values from EditorStateCache.cs - Ensures asset import is correctly detected as blocking state 3. TransportCommandDispatcher - Fix unsynchronized Count access - Moved Pending.Count check inside PendingLock - Prevents data races and InvalidOperationException from concurrent dictionary access 4. StdioBridgeHost - Fix unsynchronized Count access - Moved commandQueue.Count check inside lockObj - Ensures all collection access is properly serialized All changes maintain the GC allocation optimizations while fixing thread safety violations and semantic contract changes. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com> * fix: address code review feedback on thread safety and timeout handling - refresh_unity.py: Track readiness explicitly and return failure on timeout instead of silently returning success when wait loop exits without confirming ready_for_tools=true - McpClientConfiguratorBase.cs: Add thread safety guard for Configure() call in CheckStatusWithProjectDir(). Changed default attemptAutoRewrite to false and added runtime check to prevent calling Configure() from background threads. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> --------- Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com> |
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| DOCKER_OVERVIEW.md | ||
| Dockerfile | ||
| LICENSE | ||
| README.md | ||
| __init__.py | ||
| pyproject.toml | ||
| pyrightconfig.json | ||
| uv.lock | ||
README.md
MCP for Unity Server
Model Context Protocol server for Unity Editor integration. Control Unity through natural language using AI assistants like Claude, Cursor, and more.
Maintained by Coplay - This project is not affiliated with Unity Technologies.
💬 Join our community: Discord Server
Required: Install the Unity MCP Plugin to connect Unity Editor with this MCP server. You also need uvx (requires uv) to run the server.
Installation
Option 1: PyPI
Install and run directly from PyPI using uvx.
Run Server (HTTP):
uvx --from mcpforunityserver mcp-for-unity --transport http --http-url http://localhost:8080
MCP Client Configuration (HTTP):
{
"mcpServers": {
"UnityMCP": {
"url": "http://localhost:8080/mcp"
}
}
}
MCP Client Configuration (stdio):
{
"mcpServers": {
"UnityMCP": {
"command": "uvx",
"args": [
"--from",
"mcpforunityserver",
"mcp-for-unity",
"--transport",
"stdio"
]
}
}
}
Option 2: From GitHub Source
Use this to run the latest released version from the repository. Change the version to main to run the latest unreleased changes from the repository.
{
"mcpServers": {
"UnityMCP": {
"command": "uvx",
"args": [
"--from",
"git+https://github.com/CoplayDev/unity-mcp@v9.0.8#subdirectory=Server",
"mcp-for-unity",
"--transport",
"stdio"
]
}
}
}
Option 3: Docker
Use Pre-built Image:
docker run -p 8080:8080 msanatan/mcp-for-unity-server:latest --transport http --http-url http://0.0.0.0:8080
Build Locally:
docker build -t unity-mcp-server .
docker run -p 8080:8080 unity-mcp-server --transport http --http-url http://0.0.0.0:8080
Configure your MCP client with "url": "http://localhost:8080/mcp".
Option 4: Local Development
For contributing or modifying the server code:
# Clone the repository
git clone https://github.com/CoplayDev/unity-mcp.git
cd unity-mcp/Server
# Run with uv
uv run src/main.py --transport stdio
Configuration
The server connects to Unity Editor automatically when both are running. No additional configuration needed.
Environment Variables:
DISABLE_TELEMETRY=true- Opt out of anonymous usage analyticsLOG_LEVEL=DEBUG- Enable detailed logging (default: INFO)
Example Prompts
Once connected, try these commands in your AI assistant:
- "Create a 3D player controller with WASD movement"
- "Add a rotating cube to the scene with a red material"
- "Create a simple platformer level with obstacles"
- "Generate a shader that creates a holographic effect"
- "List all GameObjects in the current scene"
Documentation
For complete documentation, troubleshooting, and advanced usage:
Requirements
- Python: 3.10 or newer
- Unity Editor: 2021.3 LTS or newer
- uv: Python package manager (Installation Guide)
License
MIT License - See LICENSE