Ai4j App Builder

Community

LnYo-Cly

ai4j-app-builder

Use this skill when helping users build applications with AI4J in their own Java or Spring Boot projects, including first chat, streaming, tool/function calls, MCP, RAG, memory, Agent runtime, Coding Agent CLI embedding, FlowGram integration, provider configuration, dependency selection, and troubleshooting. It guides beginner-friendly app scaffolding, secure environment-variable configuration, smallest useful AI4J module selection, runnable examples, and verification steps. For AI4J repository maintenance, follow the repository AGENTS.md and Harness Anything task workflow instead of this user-facing app builder skill.

Overview

Publisher	LnYo-Cly
Repository	`ai4j`
Skill name	`ai4j-app-builder`
Stars	436
Forks	55
Bundled files	4
License	Apache-2.0
Links	Skill source Repository Homepage

Markdown instructions
A SKILL.md file the model loads on demand, so it only costs tokens when a request actually matches.
Works with any LLM
AI skills are plain Markdown, not provider-specific code, so this works with GPT, Claude, Gemini, Grok, or a local model.
4 bundled files
Scripts, templates, and references the model can read while it works. Files are read-only and never executed.
Open source
Published by LnYo-Cly on GitHub. Read the source before you install it.

Installation

Install the Ai4j App Builder AI skill in TypingMind to use it with any LLM, or drop it into another agent that reads SKILL.md.

Install in TypingMind

TypingMind installs a skill straight from its GitHub folder — it reads SKILL.md, bundles the resource files, and stores the result locally.

Open the app and go to Plugins → Skills.
Choose "Install from GitHub".
Paste the skill folder URL below and confirm.
https://github.com/LnYo-Cly/ai4j/tree/main/skills/ai4j-app-builder
Enable the skill in any chat where you want it available.

Plugins → Skills → Add skill → From GitHub URL, then paste the folder URL and press Continue.

Install in another agent

Any agent that reads the Agent Skills format can use this skill — copy the folder into that agent's skills directory.

Claude Code — .claude/skills

git clone --depth 1 https://github.com/LnYo-Cly/ai4j.git /tmp/ai4j
mkdir -p .claude/skills
cp -r /tmp/ai4j/skills/ai4j-app-builder .claude/skills/ai4j-app-builder

Restart Claude Code after copying so it picks up the new skill.

Use it in TypingMind

Enable Ai4j App Builder in any TypingMind chat and the model takes it from there. Its name and description sit in the system prompt, and the moment a request matches, the model loads the full instructions itself — you never invoke it by hand, and it costs no tokens until it is actually used.

The model loads Ai4j App Builder on its own as soon as a request matches it.

Works with any AI model

AI skills are plain Markdown instructions rather than provider-specific code, so Ai4j App Builder is not tied to the model it was written for. Install it once in TypingMind and use it with GPT-5, Claude, Gemini, Grok, DeepSeek, Mistral, Llama, or a local model you run yourself — all on your own API keys.

Loaded only when it is needed
The system prompt carries just the name and description. The instructions are fetched on the first matching request, so an idle skill costs nothing.
Switch models mid-chat
Because the skill is instructions rather than code, changing model does not break it — the next model reads the same SKILL.md.

Skill instructions

This is the SKILL.md content the model loads. Read it before installing — a skill is instructions your model will follow.

AI4J App Builder

Purpose

Use this Skill as the user-side AI4J app-building copilot. It is for people who want to use AI4J in their own Java or Spring Boot application, not for maintaining the AI4J SDK repository.

The agent should reduce integration cost by choosing the smallest correct AI4J dependency, writing a minimal runnable vertical slice, keeping secrets out of code, and proving the result with a local verification step.

Repository maintenance is outside this Skill's ownership. Read AGENTS.md and use the repository's Harness Anything (ha) task, evidence, review, and completion flow.

Startup Workflow

Identify the target project type: plain Java, Maven module, Spring Boot app, existing app, demo/prototype, RAG app, MCP integration, Agent app, Coding Agent host, or FlowGram backend.
Inspect existing build/config files when available (pom.xml, build.gradle, application.yml, controller/service layout). If no project exists, ask only for the missing minimum: Java version, build tool, app type, provider/model.
Choose the smallest AI4J module path. Read references/app-paths.md when selecting dependencies or deciding between core SDK, starter, agent, coding, and FlowGram modules.
Add configuration through environment variables or local config placeholders. Never hardcode API keys, access tokens, private endpoints, or one-person machine paths.
Implement one thin end-to-end slice before adding features: dependency -> config -> service call -> returned text/result -> verification.
Run or provide the smallest useful verification command. Read references/verification.md for build/test, live-provider, and troubleshooting patterns.

Module Selection Rules

Use ai4j for plain Java, library code, CLI tools, first chat, streaming, tool/function calls, MCP client/server, embeddings, rerank, image/audio/realtime, memory, and RAG.
Use ai4j-spring-boot-starter for Spring Boot apps that should inject AiService from ai.* configuration.
Add ai4j-agent only when the app needs agent runtime concepts such as tool loop, memory, orchestration, trace, subagent, or team behavior.
Add ai4j-coding only when the app is building a coding-agent runtime or workspace-aware automation.
Use ai4j-flowgram-spring-boot-starter only for FlowGram workflow runtime/backend integration.
Use ai4j-bom when multiple AI4J modules are used together.

Output Contract

For every build/integration answer, produce:

selected dependency path and reason
required configuration keys, with env-var placeholders
minimal code changes or generated files
exact verification command and what success means
next optional feature step, only after the first slice is runnable

Beginner Mode

When the user is new to AI4J or Java AI SDKs:

Start with Chat unless the user explicitly asks for RAG, MCP, Agent, FlowGram, or Coding Agent.
For Plain Java first chat, use the real Configuration -> AiService -> IChatService -> ChatCompletion -> ChatCompletionResponse object chain.
Prefer one controller/service/test that the user can run immediately.
Distinguish local build success from live model success. If credentials are missing, stop at a compile/mock check and say which env var is needed.
Use the user's language. Default to Chinese when the user writes Chinese.

Reference Loading

Read references/app-paths.md for dependency/module selection and docs entry routing.
Read references/recipes.md for compact implementation patterns such as first chat, Spring REST endpoint, tool call, memory, RAG, MCP, Agent, and FlowGram.
Read references/verification.md before finalizing commands, tests, troubleshooting, or live-provider caveats.

Guardrails

Do not start with RAG, Agent, or workflow orchestration when a simple Chat call solves the user's need.
Do not invent API names when the target project pins an older AI4J version. Inspect the dependency version, source, or docs available in the project.
Keep Java 8-compatible examples unless the target project already uses a higher baseline.
Keep examples provider-neutral where possible, but use OpenAI-compatible Chat as the default first slice if the user gives no provider preference.
Do not store user secrets in generated code, docs, Git-tracked config, screenshots, or logs.

Bundled files

The model reads these on demand while the skill is loaded. They are exposed as readable files and are never executed.

Frequently asked questions

What does the Ai4j App Builder AI skill do?

Why use Ai4j App Builder on TypingMind?

Because you install it once and use it with any model. Ai4j App Builder is plain Markdown rather than provider-specific code, so the same skill runs on GPT-5, Claude, Gemini, Grok, or a local model — and you can switch model mid-chat without it breaking. TypingMind runs on your own API keys, so you pay providers directly instead of a per-seat subscription, and your skills and chats stay in your own storage.

How do I install Ai4j App Builder in TypingMind?

Open Plugins → Skills → Install from GitHub in TypingMind and paste https://github.com/LnYo-Cly/ai4j/tree/main/skills/ai4j-app-builder. TypingMind reads its SKILL.md and bundles its files and installs it as a skill you can enable per chat.

Which AI models can use Ai4j App Builder?

Any model you connect in TypingMind. AI skills are plain Markdown instructions rather than provider-specific code, so GPT, Claude, Gemini, Grok, and local models can all load this skill when a request matches it.

How many AI models can I use with Ai4j App Builder?

As many as you like. As long as a model supports skills, you can use Ai4j App Builder with it — GPT, Claude, Gemini, Grok, DeepSeek, Mistral, Llama and more — all on TypingMind with your own API keys.

Is the Ai4j App Builder AI skill free?

Yes. It is published on GitHub by LnYo-Cly under the Apache-2.0 license. You only pay your own AI provider for the tokens you use.

What are AI skills?

An AI skill is a reusable instruction bundle that teaches an AI model how to do one specific task. It follows the open Agent Skills format: a SKILL.md file with a name and description, plus any scripts, templates or reference files the model may need. The model reads the instructions only when your request matches the skill, so an installed skill costs nothing until it is used.

How are AI skills different from plugins or MCP servers?

A plugin or MCP server gives a model new tools to call — code that runs somewhere and returns a result. An AI skill gives the model knowledge and process instead: how to approach a task, which steps to follow, what good output looks like. Skills are plain Markdown, so they need no server, no API key and no runtime, and they work with any model.

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Overview

Installation

Install in TypingMind

Install in another agent

Use it in TypingMind

Works with any AI model

Skill instructions

AI4J App Builder

Purpose

Startup Workflow

Module Selection Rules

Output Contract

Beginner Mode

Reference Loading

Guardrails

Bundled files

Frequently asked questions

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