unity-coding-skills

A Claude Code plugin providing skills and agents for developing Unity projects — maintainable test design and implementation, test-first workflow, coding guidelines, scene editing, and more.

Included Skills

Skill	Description	Required
code-writing-guide	Coding conventions and guidelines for Unity C# projects
edit-scene	Creates and modifies .unity and .prefab files	JetBrains MCP server and MCP Server Extension for Unity plugin
fix-bug	Diagnoses and fixes bugs using a test-first workflow (reproduce, diagnose, fix)
plan-feature	Orchestrates the test-first planning workflow for feature implementation in plan mode
refine-tests	Reviews existing test code for conformance to the test design and writing guides, then plans the refinement
run-tests	Running Unity tests via the run_unity_tests tool	JetBrains MCP server and MCP Server Extension for Unity plugin
test-designing-guide	Design maintainable test cases; reduce redundant tests, tests without assertions, and unnecessary test doubles
test-writing-guide	Conventions for writing Unity Test Framework test code	Test Helper and UI Test Helper package
unity-yaml-editing-guide	Guidelines for directly hand-editing Unity YAML asset files

Included Agents

Agent	Description
failing-test-writer	Implements test code from the plan file's Test Cases table and confirms tests fail as expected (Step 2 of dev workflow)
test-deduplicator	Removes duplicate tests and merges parameterizable tests in modified test files (Step 4 of dev workflow)
test-designer	Designs test cases during plan mode after class/method designs are produced, using the test-designing-guide skill

Installation

User-scope installation

Add the marketplace and install the plugin:

/plugin marketplace add nowsprinting/unity-coding-skills
/plugin install unity-coding-skills@nowsprinting-unity-coding-skills

Project-scope installation (team sharing)

Add the marketplace and install the plugin with --scope project:

/plugin marketplace add nowsprinting/unity-coding-skills
/plugin install unity-coding-skills@nowsprinting-unity-coding-skills --scope project

Commit the resulting .claude/settings.json to your repository.

Note

When team members trust the project folder, Claude Code prompts them to install the marketplace and plugin automatically.

Recommended Project Settings

1. MCP Server Configuration

The run-tests and edit-scene skills require JetBrains built-in MCP server and extension.

1. Enable JetBrains built-in MCP server
2. Install MCP Server Extension for Unity
3. Add the following to your project .mcp.json or user MCP settings:

{
  "mcpServers": {
    "jetbrains": {
      "type": "http",
      "url": "http://localhost:64342/stream"
    }
  }
}

Important

Do not change the MCP server name jetbrains.

Tip

The JetBrains MCP server also provides tools useful for Coding Agents, such as search_symbol and search_in_files_by_regex.

2. Enforcing coding rules via .editorconfig

Any coding rules or Roslyn analyzer diagnostics you want Claude to respect should be set to warning or higher severity in .editorconfig.

For example, to prevent leaving unused code, add the following diagnostics:

resharper_unused_type_local_highlighting = warning
resharper_unused_type_global_highlighting = warning
resharper_unused_member_global_highlighting = warning
resharper_unused_member_local_highlighting = warning

The Rider plugin for measuring complexity is also useful. e.g., CognitiveComplexity, CyclomaticComplexity

Usage

Test-first feature implementation planning

Type in plan mode:

/plan-feature <SPEC>

The created plan file includes the following:

• Layered-designed test cases
  • Reduce redundant tests, tests without assertions, and unnecessary test doubles
  • Editor tests
  • Unit tests (Play Mode tests)
  • Integrated tests including UI operation
  • Visual verification tests using image analysis
• Test-first development workflow
  • Effective (failable) test code
  • Definition of Done

Bug fixes through reproduction testing

Type out of plan mode:

/fix-bug <INCIDENT>

First, create, run, and verify a test that reproduces the bug, and then fix the bug.

Refine existing test code for conformance to the test design and writing guides

Type in plan mode:

/refine-tests <PATH>

Contributing

Contributions are welcome. However, we will decline contributions that we cannot maintain — such as adding support for different coding agents or MCP servers. Please fork this repository and customize it for your needs instead.

License

This project is released into the public domain under the Unlicense.