NowChessSystems/CLAUDE.md

Now-Chess

Scala 3.5.1 · Gradle 9

Commands

./clean      # Clear build dirs — only when necessary
./compile    # Compile all modules — always run
./test       # Run all tests
./coverage   # Check coverage

Try to stick to these commands for consistency.

Modules

Module	Role	Depends on
api	Model / shared types	(none)
core	Primary business logic	api, rule
rule	Game rules	api
io	Export formats	api, core
ui	Entrypoint & UI	core, io

Style

• Use immutable data and pure functions.
• Keep functions under 30 lines. If you need "and" to describe it, split it.
• Keep cyclomatic complexity under 15.
• Avoid comments. Let names carry intent; comment only non-obvious algorithms.
• Scan for duplicated logic before finishing. Extract it.
• Follow default Sonar style for Scala.
• Use Option or Either for fallible operations; avoid exceptions for control flow.
• Naming: types are PascalCase, functions/values are camelCase.

Code Quality

• Coverage: 100% condition coverage required in api, core, rule, io (mandatory); ui exempt.

Architecture Decisions

• Immutable state as primary model: GameContext (api) holds board, history, player state — immutable, passed through the system. Each move creates a new GameContext, enabling undo/redo without side effects.
• Observer pattern for UI decoupling: GameEngine publishes move/state events; CommandInvoker queues moves; UI listens to events, not polling. GameEngine never imports UI code.
• RuleSet trait encapsulates rules: Move generation, check, castling, en passant all in RuleSet impl. GameEngine calls rules as a black box; rules don't know about the rest of core.

Rules

• Tests are the spec. Never modify tests to pass; modify requirements or code. Update tests only if requirements change.
• Never read build folders. Ask permission if needed.
• Keep this file up to date with any important decisions or conventions.