app-inventor-extension-skill

AI Skill to develop App Inventor Extensions.

This skill teaches AI agents (Claude, etc.) how to write, build, debug, and package App Inventor / Kodular extensions (.aix files) from scratch. It covers the full extension development stack — from annotations and component lifecycle to build toolchains and dependency management.

What's inside

├── SKILL.md                        # Main skill document
├── references/
│   ├── annotations.md              # Complete annotation API reference
│   ├── aix-format.md               # AIX ZIP structure & components.json
│   ├── lifecycle.md                 # Companion vs built-app runtime, Form lifecycle
│   └── dependencies.md             # Dependency conflicts, ProGuard/R8, shading
└── README.md

What it covers

• Extension class skeleton — correct annotations, constructor pattern, PascalCase naming, type mapping
• Build toolchains — FAST (recommended) and Rush, project setup, build commands
• Full annotation API — @SimpleFunction, @SimpleEvent, @SimpleProperty, @DesignerComponent, @DesignerProperty, @Options, @IsColor, @UsesPermissions, @UsesLibraries, manifest annotations
• AIX package format — ZIP structure, classes.jar (DEX), components.json, component_build_infos.json, assets, native libs
• Component lifecycle — companion app DexClassLoader loading vs built APK, Form/Activity lifecycle hooks (OnPause, OnResume, OnDestroy, ActivityResultListener)
• Dependency management — what's already on AI2's classpath, version conflict diagnosis, ProGuard/R8 shading, AAR support
• Common idioms — async operations with event callbacks, runtime permissions, YailList, dropdown/helper blocks, multi-component extensions
• Debugging — simple_components.json introspection, companion vs APK differences, ClassNotFoundException diagnosis

Installation

Download the .skill file from Releases and install it in your AI tool of choice.

Or clone this repo and point your tool at the repository root.

Example prompts

Once installed, the skill triggers on prompts like:

• "Build me an App Inventor extension that fetches weather data from an API"
• "I'm getting ClassNotFoundException in the companion but the APK works fine"
• "Write a Kodular extension in Kotlin that wraps the Android BLE scanner"
• "What's inside an AIX file?"
• "How do I add OkHttp as a dependency without conflicting with AI2's version?"

Related projects

• FAST CLI — Feature-rich AppInventor Source Terminal
• Rush CLI — Modern extension builder for MIT AI2
• MIT App Inventor — App Inventor source code
• Kodular — No-code Android app builder (App Inventor fork)

License

MIT