Cratis Eventmodelers Build Kit — Java

Eventmodelers build kit for Cratis — turns Eventmodelers board slices into Cratis (Arc + Chronicle) vertical slices in a Java project. Connect your board to an autonomous coding agent that picks up slice status changes, implements the slice the Cratis way (Cratis Chronicle), runs ./gradlew build / ./gradlew test, and marks the work done — all without manual intervention.

Built on cratis.io. The kit is open-source (MIT) and is part of the Cratis ecosystem. The build-kit concept and realtime agent loop originate from Nebulit-GmbH/Eventmodelers-Build-Kits.

Note: The Java kit currently uses the cratis/chronicle/client-java profile from the Cratis AI corpus. Additional profiles for Java (e.g., cratis/application/java, cratis/arc/java) are planned for future releases.

Start here

• Install the kit — get the Cratis starter app and agent loop
• What the kit owns — capabilities and boundaries
• Usage — how to run the agent loop
• Cratis AI corpus — generated conventions and skills
• Documentation — full walkthroughs: install, run your first slice, connect a board, the loop, CLI reference
• License — MIT
• Sibling kits — C# and Kotlin variants

Install

Run the installer in your project directory:

npx github:Cratis/Eventmodelers-Build-Kit-Java install

It will:

• Copy the Cratis starter app into your project root (Java backend with Arc + Chronicle, example slice, shared React frontend, CLAUDE.md).
• Install the loop machinery and skills into .build-kit/ (gitignored automatically).
• Prompt for board credentials (org ID, board ID, token) → .build-kit/.eventmodelers/config.json.
• Configure the Eventmodelers MCP server in .build-kit/.claude/settings.json.

Path	Purpose
.build-kit/.claude/skills/build-state-change	Write-slice skill (Cratis commands/events)
.build-kit/.claude/skills/build-state-view	Read-slice skill (read models/projections)
.build-kit/.claude/skills/build-automation	Automation/translation skill (reactors)
.build-kit/.claude/skills/_shared/cratis-conventions.md	The distilled Cratis conventions
.build-kit/.claude/skills/{connect,load-slice,update-slice-status,learn-eventmodelers-api}	Platform skills
.build-kit/ralph-claude.js / ralph.sh	The agent loop
.build-kit/lib/prompt.md / backend-prompt.md	Agent instructions
.build-kit/lib/AGENT.md	Accumulated learnings across iterations

Usage

./gradlew build    # backend + Java proxy generation
./gradlew test     # run tests

Start the agent loop:

# Claude (default)
node .build-kit/ralph-claude.js

# Local Ollama model (run `ollama serve` first)
OLLAMA_MODEL=qwen3:8b node .build-kit/ralph-ollama.js

# Target a custom project directory
node .build-kit/ralph-claude.js /path/to/project

What the kit owns

Boundary	Kit provides
Installation	Cratis starter app with Chronicle, Java backend, and example slice
Agent loop	ralph — autonomous Claude agent that reacts to slice:changed events
Build skills	/build-state-change, /build-state-view, /build-automation for implementing slices
Platform skills	/connect, /load-slice, /update-slice-status, /learn-eventmodelers-api for board integration
Generated conventions	cratis-conventions.md derived from the Cratis AI corpus
MCP server	Eventmodelers platform integration configured in .claude/settings.json

Cratis AI corpus

The .cratis/ai/ directory and templates/.claude/skills/_shared/ are generated by cratis ai update and scripts/sync-corpus-to-templates.mjs. They are refreshed on every release and must not be hand-edited. The generated cratis-conventions.md is derived from the Cratis AI corpus selected by the profiles in .cratis/ai.json.

License

MIT

Sibling kits

• Eventmodelers Build Kit — C# — C# variant
• Eventmodelers Build Kit — Kotlin — Kotlin variant