What problem does it solve? Static calls like DateTime.UtcNow and File.ReadAllText make C# code untestable and tightly coupled. This Skill performs codemod-style bulk replacement of those call sites with injected abstractions such as TimeProvider or IFileSystem, including constructor injection and test updates, within a bounded file, project, or namespace scope. ## Core Features & Use Cases - Bulk call-site replacement: Migrates DateTime.Now/UtcNow to TimeProvider, File.* to IFileSystem, and similar statics, with a mapping table that preserves DateTimeKind to avoid silent regressions. - Constructor injection and ambient seams: Adds constructor or primary-constructor parameters following existing naming conventions, and applies an ambient static seam pattern for static classes that cannot receive injection. - Test updates and build verification: Updates unit tests to use FakeTimeProvider or MockFileSystem, verifies DI registration, and runs dotnet build to confirm the migration compiles. - Use Case: Migrate all DateTime.UtcNow usages in one service project to TimeProvider, add the constructor parameter to affected classes, and update their tests to use a controllable fake clock. ## Quick Start Replace all DateTime.UtcNow calls in the Services project with TimeProvider, add constructor injection, and update the corresponding unit tests to use FakeTimeProvider.
