typer-patterns

Type-safe Python CLIs with Typer require end-to-end type hints on all parameters and return types, combined with Typer decorators and imports. This Skill provides patterns, templates, and example implementations that enforce type safety throughout your CLI, reducing bugs and improving IDE support for maintainable command-line applications.

Sub-apps in Typer organize large CLIs into nested command groups using Typer's app factory pattern. This Skill covers structured architectures with nested sub-apps, dependency injection, and factory-pattern designs that scale CLI complexity while maintaining clear, testable code organization.

Enums in Python CLIs provide type-safe, autocomplete-friendly option choices. This Skill demonstrates enum-based options with Typer that constrain user input to valid values, enable shell completion, and integrate seamlessly with type hints for validated, maintainable command parameters.

Factory patterns with Typer apps decouple app initialization from business logic, enabling easier unit testing and dependency injection. This Skill covers optional factory-pattern architectures that improve test coverage and code reusability across CLI applications.

Type hints in Typer require Python's type annotation syntax but this Skill provides templates and example CLIs that demonstrate practical patterns. Starting with basic apps and progressively adding sub-apps, enums, and validators makes type-safe CLI development accessible while building maintainability.