craft-concernlisted

# Skill: Craft Concern > "A concern wires behavior. It never owns it." ## The Standard 1. **Thin Methods**: Delegate to query builders, collections, and actions. 2. **Naming**: `Has*`, `Interacts*`, `Can*` — match Laravel conventions. 3. **No Business Logic**: Conditionals or transformations? Extract. 4. **Boot Convention**: Use `boot{TraitName}` for model event hooks. A concern method does **one of three things**: | Delegation Target | Concern Method Does | |-------------------|--------------------------------------| | **QueryBuilder** | Returns a query scope or builder | | **Collection** | Returns a filtered/mapped collection | | **Action** | Calls an action and returns result | If it does more, it's too fat. Extract. ## The Anti-Patterns | Don't | Do | Why | |-------------------------|-------------------------------|--------------------------------| | Business logic in trait | Delegate to Action | Traits mix in, logic leaks | | Complex queries inline | Delegate to QueryBuilder | Reusable, testable | | Collection manipulation | Delegate to custom Collection | Named pipeline | | Deep conditionals | Guard clause or Action | Traits should be flat | | State mutations | Delegate to Action | Side effects belong in Actions | ## Real-World Examples See [examples.md](examples.md).