unity-webgl

name	unity-webgl
description	Unified Unity WebGL skill for JavaScript interop plugins, WebGL build optimization, deployment, and custom HTML templates. Auto-triages JSLib, Build, and Template work. MUST use for Unity WebGL requests: .jslib plugins, calling JS from Unity, browser APIs, build size, compression, memory, linker.xml, Player Settings, deployment, server MIME types, loading screens, templates, responsive canvas, iframe embedding, localStorage, Brotli, platform-conditional code, or issues that work in Editor but fail in WebGL. Do not use for general runtime C#, editor scripts, or non-WebGL debugging.
metadata	{"author":"kuozg","version":"1.1"}

unity-webgl

Detect what the user needs for WebGL, select mode, deliver complete platform-specific code.

Step 1 — Detect Mode

Signal	Mode
.jslib, call JS from C#, browser API (clipboard, localStorage, URL params, fullscreen)	JSLib
Build size, compression, linker.xml, memory, Player Settings, deployment, server MIME types	Build
HTML template, loading screen, responsive canvas, iframe, custom shell, progress bar	Template

State triage: "This is [mode] — [reason]."

Step 2 — Execute

JSLib Mode:

1. Check existing Assets/Plugins/WebGL/ for .jslib files and patterns; read any C# bridge classes
2. Implement both sides: .jslib using mergeInto(LibraryManager.library, {...}) + C# class with [DllImport("__Internal")] extern methods + #if UNITY_WEBGL && !UNITY_EDITOR guards on call sites
3. Load references/jslib-patterns.md for marshalling rules
4. lsp_diagnostics on C# files; validate .jslib has valid JS syntax
5. Handoff: file paths, what each side does, testing guidance (must test in browser build)

Build Mode:

1. Check existing ProjectSettings/, linker.xml, build scripts, compression settings
2. Load references/build-optimization.md for settings reference
3. For code stripping: create/update linker.xml · For compression: recommend Brotli (HTTPS) or Gzip + server config · For memory: configure heap size
4. Validate XML syntax; confirm no conflicting settings
5. Handoff: changed files, expected build size impact, server setup instructions

Template Mode:

1. Check Assets/WebGLTemplates/ for existing templates; read current index.html
2. Load references/template-customization.md for variables and patterns
3. Create/modify: index.html with Unity template variables ({{{ PRODUCT_NAME }}}) · responsive CSS · JS for error handling, mobile detection, fullscreen
4. Validate HTML structure; ensure all Unity template variables present
5. Handoff: file paths, how to select template in Build Settings, browser testing notes

Rules

• Wrap WebGL-only C# calls in #if UNITY_WEBGL && !UNITY_EDITOR — must compile on all platforms
• .jslib files go in Assets/Plugins/WebGL/ — path matters for build pipeline
• String marshalling in JSLib: UTF8ToString() for incoming strings; _malloc + stringToUTF8 for return strings — never skip buffer allocation
• SendMessage is legacy — prefer [DllImport("__Internal")] for C#→JS calls
• Never use System.Threading, System.IO.File, raw System.Net.Sockets in WebGL paths
• Always provide fallback behavior for non-WebGL platforms
• lsp_diagnostics after every code change

Escalation

To	When
unity-code	Work is pure C# with no JS interop
unity-debug	Build fails with compile errors
unity-uitoolkit	User wants runtime UI, not HTML shell
unity-debug	"Works in editor but not in WebGL" with runtime errors

Standards

read_skill_file("unity-standards", "references/<path>"):

• code-standards/architecture-systems.md · code-standards/lifecycle-async-errors.md
• debug/common-unity-errors.md · other/unity-mcp-routing-matrix.md

read_skill_file("unity-webgl", "references/<path>"):

• jslib-patterns.md · build-optimization.md · template-customization.md