foundry-vtt

name	foundry-vtt
description	Foundry VTT virtual tabletop. This skill should be used when developing modules/systems (ApplicationV2, hooks, DataModels, Handlebars), deploying via Docker/Helm with Traefik, or working with WFRP4e.
last_updated	"2026-03-20T00:00:00.000Z"

Foundry VTT

Virtual tabletop platform for TTRPGs. Node.js server, WebSocket-based, extensible via modules and game systems. Current version: v13.

Key Concepts

• Module: Extends/modifies Foundry functionality (like a plugin)
• System: Defines game rules, data schemas, sheets (e.g., dnd5e, pf2e)
• Document: Core data type (Actor, Item, Scene, JournalEntry, ChatMessage, Macro, RollTable, Playlist, Cards)
• Application: UI window class (legacy Application v1, modern ApplicationV2)
• Hook: Event system for lifecycle/render/document events

Module Quick Start

mymodule/
├── module.json          # Package manifest (required)
├── scripts/
│   └── main.mjs         # Entry point (esmodules)
├── templates/            # Handlebars .hbs files
├── styles/               # CSS files
├── packs/                # Compendium data
└── lang/
    └── en.json           # Localization

Minimal module.json:

{
  "id": "my-module",
  "title": "My Module",
  "version": "1.0.0",
  "compatibility": { "minimum": 12, "verified": "13" },
  "esmodules": ["scripts/main.mjs"],
  "styles": ["styles/module.css"]
}

Entry point pattern:

Hooks.once("init", () => {
  console.log("Module initializing");
  game.settings.register("my-module", "mySetting", {
    name: "My Setting",
    scope: "world",     // "world" or "client"
    config: true,       // show in settings UI
    type: Boolean,
    default: false
  });
});
Hooks.once("ready", () => {
  console.log("Module ready");
});

Bundled Frameworks

Library	Purpose
Handlebars	HTML templating for Application UIs
PixiJS	Canvas rendering (lighting, tokens, drawings)
jQuery	DOM manipulation (legacy, being phased out)
GreenSock (GSAP)	SVG/WebGL animation
ProseMirror	Rich text editing (v12+)

Top Dev Frameworks/Libraries

Tool	Purpose
Vite	Build tool with HMR, serves dev builds through Foundry
TypeScript + @league-of-foundry-developers/foundry-vtt-types	Type safety
Svelte + TyphonJS Runtime Library (TRL)	Reactive UI components
libWrapper	Safe method patching without conflicts
socketlib	Simplified socket communication abstraction
Quench	In-Foundry test runner (Mocha + Chai + fast-check)
Foundry DevMode	Developer tools module by League of Foundry Developers
Rollup/Webpack	Alternative bundlers

Reference Files

File	Content
references/modules/manifest.md	module.json and system.json manifest fields, package structure
references/modules/documents-hooks.md	Document model, hooks system, lifecycle events
references/modules/sheets-templates.md	ApplicationV2, HandlebarsApplicationMixin, sheet registration
references/modules/sheets-templates-handlebars.md	Legacy App v1, Handlebars syntax, helpers, partials
references/modules/data-models.md	TypeDataModel schemas, field types, data preparation, migration
references/modules/data-models-settings.md	Game Settings API, module sub-types, flags, localization
references/modules/libraries.md	libWrapper, socketlib, Vite setup, TypeScript, Svelte/TRL
references/modules/libraries-tools.md	Foundry DevMode debug flags, notifications, dialogs, dice, canvas
references/deployment/k3s.md	K3s/Kubernetes deployment, Helm charts, Traefik ingress, resources
references/deployment/k3s-manifests.md	Raw K8s manifests: Namespace, Secret, PVC, Deployment, Service
references/deployment/docker.md	felddy/foundryvtt-docker env vars, compose, configuration
references/testing/quench.md	Quench test framework, test batches, Mocha/Chai/fast-check
references/testing/quench-patterns.md	Quench snapshots, running via API, batch conventions, TypeScript
references/testing/ci-testing.md	Vitest unit testing, Foundry API mocks, test fixtures
references/testing/ci-testing-pipeline.md	GitHub Actions CI pipeline, ZIP packaging, release workflow
references/systems/wfrp4e.md	WFRP4e: game.wfrp4e API, actor/item types, custom species
references/systems/wfrp4e-effects.md	WFRP4e effects triggers, world scripts, dev setup, community modules

Cross-References

• K3s cluster: Use k3s skill for cluster setup before deploying Foundry
• Ingress: Use traefik skill for IngressRoute with WebSocket middleware
• Storage: Use rook-ceph skill for persistent storage backing Foundry data
• GitOps: Use argocd skill for deploying Foundry via ApplicationSets
• Helm: Use helm skill for chart customization and values management