unity-coding-skills
A Claude Code plugin for Unity development that enables coding agents to work autonomously through a test-first workflow — writing reliable, maintainable tests before production code, then iterating to completion without constant oversight.
Reliable tests give the agent a clear signal: green means done.
This plugin provides the methodology, conventions, and tools to make that signal trustworthy.
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 | 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 | |
resolve-diagnostics | Resolves IDE diagnostics at warning or higher severity in the specified files, then reformats them | MCP server |
run-tests | Running Unity tests via the run_unity_tests tool | 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 Subagents
| 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 the JetBrains Rider built-in MCP server and extension.
- Enable built-in MCP Server
- Click the "Auto-Configure" button
- Install MCP Server Extension for Unity plugin
[!IMPORTANT]
JetBrains Rider 2026.2 or later is recommended.
[!IMPORTANT]
On Rider 2026.2, when both the JetBrains and Rider MCP toolsets are enabled, they expose tools with the same name.
Prefer the tools provided by Rider, and disable the duplicates:
- Under the Analysis toolset:
get_file_problems, lint_files
- Under the Formatting toolset:
reformat_file
[!TIP]
The JetBrains MCP server also provides tools useful for coding agents, such as list_directory_tree, search_file, search_regex, search_symbol, and search_text.
[!NOTE]
The MCP server is registered under different names depending on your Rider version: rider on Rider 2026.2 or later, jetbrains on versions earlier than 2026.2.
[!NOTE]
When Rider is earlier than 2026.2 and you are using other JetBrains IDEs simultaneously with Rider, port numbers are assigned in the order they are launched.
For example, if you launch Rider after IDEA, the port number for Rider will be 64343.
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 types and members, 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
[!TIP]
You can find the open-source Roslyn analyzer version compatible with your project's Unity version in
Which version of Roslyn analyzers should I use with Unity?.
[!TIP]
The following Rider plugins for measuring complexity are also useful:
3. Ignoring temporary files via .gitignore
The skills place temporary editor script files under Assets/UnityCodingSkills/. Adding the following pattern to your project's .gitignore is recommended:
Assets/UnityCodingSkills*
Usage
Test-first feature implementation planning
Type in plan mode:
/plan-feature <SPEC>
The created plan file includes the following:
- Layered-designed test cases to reduce redundant tests, tests without assertions, and unnecessary test doubles:
- Editor tests (Edit Mode tests for editor extensions and validate assets)
- Unit tests (Play Mode tests for runtime code)
- Integration tests including UI operation and layout assertions
- Visual verification tests using image analysis
- Test-first development workflow
- Effective (failable) test code
- Definition of Done
- Safe refactoring to improve internal quality (uses
/simplify skill and static analysis)
Bug fixes through reproduction testing
Type out of plan mode:
/fix-bug <INCIDENT>
Create, run, and verify tests to reproduce the bug, then fix it.
[!TIP]
The INCIDENT can specify an issue description or the failed test name.
[!NOTE]
Depending on the incident, the root cause may be identified before writing a reproduction test. Under adjustment.
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.
