style-guidelines.instructions.md

apply-to	**/*.cs

Namespaces

• Use file-scoped namespaces that match the directory structure.

Immutability

• Prefer immutable types unless mutability is requested.
• Prefer records for immutable types.

Files Organization

• Define one type per file.

Record Design

• Define record's properties on the same line as the record declaration.
• Use immutable collections in records unless requested otherwise.
• Use ImmutableList<T> in records whenever possible.
• Define record behavior in extension methods in other static classes.

Discriminated Unions Design

• Prefer using records for discriminated unions.
• Derive specific types from a base abstract record.
• Define the entire discriminated union in one file.
• Define one static factory class per discriminated union.
• Expose one static factory method per variant.
• Follow all rules for record design when designing a discriminated union.

Domain Models Design

• Use a private constructor for domain models.
• Properties should be defined as get; private set;.
• Collections should be defined as IReadOnlyCollection<T> or IReadOnlyList<T> and have a private backing field.
• Expose static Create method in the domain class for creating instances of the domain model.
• Place argument validation in the Create method.