patterns

Name the concrete force present today, such as multiple payment providers or a crash-survival requirement. If the sentence needs 'might' or 'later', there is no force yet, so use the simplest default like a function, dict, or enum instead.

Avoid a speculative Repository when the ORM already abstracts storage, since it creates two persistence layers with one empty. Add a Repository only when a second store or a real test seam is present.

Singleton introduces hidden global state, is untestable, and breaks under concurrency. The recommended default is constructor injection, passing the single instance in while the composition root owns its lifetime.

A ledger is one line per surviving pattern in the spec's Design notes, formatted as pattern / force / rejected alternative. A pattern without a ledger line is treated as pattern-stuffing and flagged as a Blocker by reviewers.

Six domain files route forces to patterns: backend.md for APIs and persistence, frontend.md for UI state, mobile.md for navigation and sync, game.md for Unity, desktop.md for MVVM and undo, and concurrency.md for workers and circuit breakers.