MiddlewareContextThe per-chain-step state exposed to middleware via the chain walker. Constructed by the chain walker for each middleware invocation.MiddlewareItemsA typed dictionary wrapper for sharing data between middleware steps. Backed by IDictionary<TKey, TValue>.ProcessMiddlewareBuilderPublic builder for composing a sequence of IProcessMiddleware instances. Supports direct middleware registration, type-based resolution, and conditional sub-pipelines via UseWhen(Func<InvocationContext, Boolean>, Action<IProcessMiddlewareBuilder>).IProcessMiddlewareThe async-only contract for process middleware. Implementations intercept the pipeline by calling next to continue, or omitting the call to short-circuit the chain.IProcessMiddlewareBuilderA builder for composing a sequence of IProcessMiddleware instances.IRetryClassifierClassifies whether a failed process result should be retried.