Leyline

Open-source local playtesting server built around a client protocol bridge and the Forge rules engine.

Leyline exposes two heads over one match engine: a native-client-compatible head and a browser-facing web head.

flowchart LR
    NC["Native client"] --> N["Native head"]
    B["Browser"] --> W["Web head"]
    N --> E["Leyline engine"]
    W --> E
    E --> F["Forge rules engine"]

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Forge owns game rules and legality. Leyline translates between synchronous engine decisions and asynchronous protocol interactions, then projects engine state into client-facing updates.

Architecture deep dive →

Repository shape

app/         Composition root, local control, and management
domain/      Shared domain model, services, and repository ports
engine/      Forge adapter, match runtime, and state projection
proto/       Generated GRE schema (submodule + rename map → protoc)
native/      Native account, lobby, and match transports
web/         Browser HTTP and WebSocket head
forge/       Forge submodule

Build and run

git clone --recursive https://github.com/delebedev/leyline.git
cd leyline
just bootstrap
just serve

Requires JDK 21+, just, and macOS or Linux. End-to-end native-client play needs a compatible client installed separately and the local setup described in docs/local-client-setup.md.

Test

just test-gate                 # formatting and repository test gate
just test-one MyTest engine   # one focused test class
just puzzle-check file.pzl    # validate a puzzle fixture

Puzzle-backed scripted suites exercise complete gameplay paths. See docs/puzzle-harness.md for fixture boundaries.

Design stance

• Playable behavior first. A change is complete when its user-facing path works, not merely when a lower layer compiles.
• Forge owns rules. Leyline adds narrow integration seams instead of duplicating game logic.
• Explicit boundaries. Live Forge handles stay in the imperative shell; projection consumes immutable values.
• Local interoperability. The project implements client-compatible protocols without distributing client assets.

Scope

Leyline is a local server for personal playtesting and protocol/runtime experimentation. It is not a public or hosted game service and does not distribute card art, sounds, or other game assets.

License

GPL-3.0, inherited from Forge. See LICENSE, LEGAL, and NOTICE.

Architecture · Security · Contributing

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This project is not affiliated with, endorsed by, or connected to Wizards of the Coast, Hasbro, or any of their affiliates. "Magic: The Gathering" is a trademark of Wizards of the Coast LLC.