by niaka3dayo
Skills, rules, and validation hooks that teach AI coding agents to generate correct UdonSharp code
# Add to your Claude Code skills
git clone https://github.com/niaka3dayo/agent-skills-vrc-udonGuides for using ai agents skills like agent-skills-vrc-udon.
Last scanned: 5/30/2026
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}agent-skills-vrc-udon is an open-source ai agents skill for AI coding assistants such as Claude Code, Codex CLI, and ChatGPT, built by niaka3dayo. Skills, rules, and validation hooks that teach AI coding agents to generate correct UdonSharp code. It has 186 GitHub stars.
Yes. agent-skills-vrc-udon passed SkillsLLM's automated security scan — a dependency vulnerability audit plus prompt-injection heuristics — with no high-severity issues. You can read the full report in the Security Report section on this page.
Clone the repository with "git clone https://github.com/niaka3dayo/agent-skills-vrc-udon" and add it to your Claude Code skills directory (see the Installation section above).
agent-skills-vrc-udon is primarily written in C#. It is open-source under niaka3dayo on GitHub, so you can review or fork the full source.
Yes. SkillsLLM lists many other AI Agents skills you can browse and compare side by side. Open the AI Agents category from the badge at the top of this page, or use the Related Skills and comparison links further down to weigh agent-skills-vrc-udon against similar tools.
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English | 日本語 | 简体中文 | 繁體中文 | 한국어
VRChat world development with UdonSharp (C# → Udon Assembly) has strict compile constraints that differ significantly from standard C#. Features like List<T>, async/await, try/catch, LINQ, and lambdas cause compile errors.
This repository provides AI coding agents with the knowledge to generate correct UdonSharp code from the start.
| Problem | Solution |
|---|---|
AI generates List<T>, async/await, etc. |
Rules + hooks auto-detect and warn |
| Sync variable bloat | Decision tree + data budget |
| Incorrect networking patterns | Pattern library + anti-patterns |
| SDK version feature differences | Version table with feature mapping |
| Late Joiner state inconsistency | Sync pattern selection framework |
This is NOT:
Issues: Bug reports and knowledge requests are welcome via GitHub Issues. PRs: Pull Requests are not accepted. See CONTRIBUTING.md for details.
Migrating from fork/clone? — Since v1.0.0, this project is distributed as an npm package. You no longer need to fork or clone the repository. Simply run one of the install commands below inside your VRChat Unity project. If you previously cloned this repo, you can safely delete the cloned directory and switch to the npm-based install.
npx skills add niaka3dayo/agent-skills-vrc-udon
This uses the skills.sh ecosystem to install skills into your project.
claude plugin add niaka3dayo/agent-skills-vrc-udon
git clone https://github.com/niaka3dayo/agent-skills-vrc-udon.git
skills/ # All skills
unity-vrc-udon-sharp/ # UdonSharp core skill
SKILL.md # Skill definition + frontmatter
LICENSE.txt # MIT License
CHEATSHEET.md # Quick reference (1 page)
rules/ # Constraint rules
udonsharp-constraints.md
udonsharp-networking.md
udonsharp-sync-selection.md
hooks/ # PostToolUse validation
validate-udonsharp.sh
validate-udonsharp.ps1
assets/templates/ # Code templates (17 files)
references/ # Detailed documentation (23 files)
unity-vrc-world-sdk-3/ # VRC World SDK skill
SKILL.md, LICENSE.txt, CHEATSHEET.md, references/ (7 files)
templates/ # AI tool config templates
CLAUDE.md AGENTS.md GEMINI.md # Distributed to users via installer
.claude-plugin/marketplace.json # Claude Code plugin registration
CLAUDE.md # Development guide (this repo only)
UdonSharp scripting core skill. Covers compile constraints, networking, events, and templates.
| Area | Content |
|---|---|
| Constraints | Blocked C# features and alternatives (List<T> → DataList, async → SendCustomEventDelayedSeconds) |
| Networking | Ownership model, Manual/Continuous sync, FieldChangeCallback, anti-patterns |
| NetworkCallable | SDK 3.8.1+ parameterized network events (up to 8 args) |
| Persistence | SDK 3.7.4+ PlayerData/PlayerObject API |
| Dynamics | SDK 3.10.0+ PhysBones, Contacts, VRC Constraints for Worlds |
| Web Loading | String/Image download, VRCJson, VRCUrl constraints |
| Templates | 17 templates (interactions, sync patterns, persistence, editor utilities, and more) |
World-level scene setup, component placement, and optimization.
| Area | Content |
|---|---|
| Scene Setup | VRC_SceneDescriptor, spawn points, Reference Camera |
| Components | VRC_Pickup, Station, ObjectSync, Mirror, Portal, CameraDolly |
| Layers | VRChat reserved layers and collision matrix |
| Performance | FPS targets, Quest/Android limits, optimization checklist |
| Lighting | Baked lighting best practices |
| Audio/Video | Spatial audio, video player selection (AVPro vs Unity) |
| Upload | Build and upload workflow, pre-upload checklist |
Rules are constraint files that guide AI agents before code generation.
| Rule File | Content |
|---|---|
udonsharp-constraints |
Blocked C# features, code generation rules, attributes, syncable types |
udonsharp-networking |
Ownership model, sync modes, anti-patterns, NetworkCallable constraints |
udonsharp-sync-selection |
Sync decision tree, data budget targets, 6 minimization principles |
Q1: Visible to other players?
No --> No sync (0 bytes)
Yes --> Q2
Q2: Late Joiner needs current state?
No --> Events only (0 bytes)
Yes --> Q3
Q3: Continuous change? (position/rotation)
Yes --> Continuous sync
No --> Manual sync (minimal [UdonSynced])
Target: < 50 bytes per behaviour. Small-medium worlds: < 100 bytes total.
PostToolUse hooks that auto-run when .cs files are edited.
| Category | Check | Severity |
|---|---|---|
| Blocked Features | List<T>, async/await, try/catch, LINQ, coroutines, lambdas |
ERROR |
| Blocked Patterns | AddListener(), StartCoroutine() |
ERROR |
| Networking | [UdonSynced] without RequestSerialization() |
WARNING |
| Networking | [UdonSynced] without Networking.SetOwner() |
WARNING |
| Sync Bloat | 6+ synced variables per behaviour | WARNING |
| Sync Bloat | int[]/float[] sync (recommend smaller types) |
WARNING |
| Config Mismatch | NoVariableSync mode with [UdonSynced] fields |
ERROR |
Supports both Bash (validate-udonsharp.sh) and PowerShell (validate-udonsharp.ps1).
| SDK Version | Key Features | Status |
|---|---|---|
| 3.7.1 | StringBuilder, Regex, System.Random |
Supported |
| 3.7.4 | Persistence API (PlayerData / PlayerObject) | Supported |
| 3.7.6 | Multi-platform Build & Publish (PC + Android) | Supported |
| 3.8.0 | PhysBone dependency sorting, Force Kinematic On Remote | Supported |
| 3.8.1 | [NetworkCallable] parameterized events, Others/Self targets |
Supported |
| 3.9.0 | Camera Dolly API, Auto Hold pickup | Supported |
| 3.10.0 | VRChat Dynamics for Worlds (PhysBones, Contacts, VRC Constraints) | Supported |
| 3.10.1 | Bug fixes, stability improvements | Supported |
| 3.10.2 | EventTiming.PostLateUpdate/FixedUpdate, PhysBones fixes, shader time globals | Supported |
| 3.10.3 | VRCPlayerApi.isVRCPlus, VRCRaycast (avatar), Mirror render-order fix |
Latest Stable |
Note: SDK < 3.9.0 was deprecated on December 2, 2025. New world uploads require 3.9.0+.
| Resource | URL |
|---|---|
| VRChat Creators Docs | https://creators.vrchat.com/ |
| UdonSharp API Reference | https://udonsharp.docs.vrchat.com/ |
| VRChat Forums (Q&A) | https://ask.vrchat.com/ |
| VRChat Canny (Bugs/Features) | https://feedback.vrchat.com/ |
| VRChat Community GitHub | https://github.com/vrchat-community |
Issues are welcome -- bug reports and knowledge requests help improve this project.
Pull Requests are not accepted -- all fixes and updates are made by the maintainer.
See CONTRIBUTING.md for details.
This project is not affiliated with VRChat Inc. No official endorsement, partnership, or association is implied.
"VRChat", "UdonSharp", "Udon" and related names/logos are trademarks of VRChat Inc. All trademarks belong to their respective owners.
This repository is a personal knowledge base for AI coding agents to generate correct UdonSharp code. It does not