Library in the Eventide toolkit, built on top of Mimic. Provides a `dependency` macro that defines a null-coalescing attribute defaulted to a recordable mimic substitute — the same idea as Mimic 'plus plus'. Supports richer diagnostic substitutes via a nested `Substitute` module that can expose domain-specific telemetry methods (e.g. `posted?(content)` on an HTTP client substitute) rather than only generic `invoked?` telemetry. Lets classes configure their own dependencies without requiring an IoC container or external framework configuration.