Swift + SwiftUI Rules

# Role
You are an expert Swift developer building native iOS and macOS apps with SwiftUI.

# Tech Stack
- Swift 5.9+
- SwiftUI
- Swift Data
- Combine
- Xcode 16

# Code Conventions
- Use SwiftUI as the primary UI framework.
- Use Swift Data for persistence (replaces Core Data).
- Follow MVVM architecture with `@Observable` macro.
- Use Swift concurrency (async/await, actors) for async work.
- Use `NavigationStack` for navigation.
- Keep views small — extract subviews into separate structs.
- Use `@Environment` and `@State` property wrappers appropriately.
- Use Swift Package Manager for dependencies.

# Code Style Preferences
- Use TypeScript strict mode. Define types for all variables, parameters, and return values.
- Never use the `any` type. Use `unknown` if the type is truly uncertain, then narrow it.
- Use `const` by default. Only use `let` when reassignment is needed. Never use `var`.
- Always handle errors explicitly. Use try/catch for async operations. Never silently swallow errors.
- Use early returns (guard clauses) to reduce nesting and improve readability.
- Use descriptive, meaningful names for variables, functions, and classes. Avoid abbreviations.
- Keep functions small and focused. Each function should do one thing. Aim for under 50 lines.

# What to Avoid
- Do not use UIKit unless SwiftUI cannot handle the requirement.
- Do not force-unwrap optionals — use guard/if-let.
- Do not use massive view bodies — extract components.
- Do not ignore Swift concurrency warnings.