Shared Code Guardrail

Code Placement Decision Tree

When writing new code, ask:

1. Is this SHARED between loh-game AND loh-backend?
   └─> YES → loh-libs/rust/shared-protocol/

2. Is this UI-specific (Egui, Bevy rendering, input handling)?
   └─> YES → loh-game/src/systems/ui/ or relevant system

3. Is this backend-specific (API handlers, database, auth)?
   └─> YES → loh-backend/

Infrastructure Context

What Goes to loh-libs

• DTOs (Data Transfer Objects) for API communication
• Enums shared between client/server (e.g., OrderSide, SkillType)
• Validation logic that must be consistent
• Math/calculation utilities used by both
• Combat damage formulas, XP tables, loot calculations

What Stays in loh-game

• Bevy-specific: Component, Resource, SystemParam
• UI rendering (Egui widgets, panels, themes)
• Input handling, camera controls
• VFX, audio, rendering systems
• Game loop, player state

What Stays in loh-backend

• sqlx derives (FromRow, Type)
• Cloudflare Worker handlers
• Database migrations, API routes
• Authentication (JWT, sessions)
• Payment processing

Check Before Adding Types

1. Does this type appear in both codebases?
2. Does it need to serialize/deserialize for network communication?
3. Is validation logic duplicated?

Directory Structure

loh-libs/rust/shared-protocol/src/types/
├── combat.rs    # Combat stats, damage types
├── economy.rs   # Market orders, snapshots (OrderSide, MarketSnapshot)
├── item.rs      # Item definitions
├── loot.rs      # Loot tables
├── npc.rs       # NPC data
└── skill.rs     # Skill types

Adding New Shared Types

1. Create/edit file in shared-protocol/src/types/
2. Add pub mod X; to types/mod.rs
3. Add pub use types::X::*; to lib.rs
4. Update both loh-game/Cargo.toml and loh-backend/*/Cargo.toml if needed

Automated Check

// turbo
python3 scripts/check_shared_code.py