What is the recommended data structure for V13?

V13 strongly recommends using foundry.abstract.DataModel for structured data, which provides built-in validation, schema definitions, and better integration with the Foundry document system.

Why is the change from actor.data.data to actor.system important?

Foundry V13 continues the deprecation of the V10-era data structure; using actor.system is required for modern compatibility and proper integration with DataModels.

Does this skill help with broken hooks after upgrading?

Yes, it specifically identifies and corrects hook signatures that changed between V12 and V13, such as the createToken hook which now uses different argument structures.

How does this skill handle CommonJS to ESM conversion?

The skill provides patterns for replacing require() calls with import/export statements and ensures the module manifest correctly uses the 'esmodules' field instead of 'scripts'.

Foundry VTT V13 Migration

Name: Foundry VTT V13 Migration
Author: ImproperSubset

byImproperSubset

0•

Game Development

Guides developers through migrating Foundry VTT modules and systems to Version 13 using modern ESM and DataModel patterns.

This skill provides a specialized framework for updating Foundry Virtual Tabletop codebases to the V13 architecture. It assists developers in converting legacy CommonJS to ECMAScript Modules (ESM), replacing deprecated data access patterns with structured DataModels, and correcting breaking changes in hook signatures and manifest configurations. By implementing these industry-standard patterns, developers can ensure their modules are performant, valid, and fully compatible with the latest Foundry core updates while avoiding common pitfalls like incorrect hook arguments or legacy data structures.

Key Features

01Transitioning legacy actor.data.data patterns to modern actor.system

020 GitHub stars

03Automated conversion from legacy CommonJS to ESM (ECMAScript Modules)

04Implementation of foundry.abstract.DataModel for schema-based validation

05Correction of updated V13 hook signatures and event arguments

06Manifest verification for V13 compatibility and esmodules declarations

Use Cases

01Upgrading a V11 or V12 module to meet V13 verified compatibility requirements

02Refactoring plain JavaScript data structures into validated DataModels

03Converting module scripts to ESM format to comply with V13 standards

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add impropersubset/hh-agentics fvtt-v13-migration

For use in Claude.ai and ChatGPT

Download Skill