Enhance mediator functionality with manual handler registration

[PascalSenn]

• Introduced AddHandler<T>() method for manual registration of command, query, and notification handlers.
• Updated documentation to reflect changes in handler registration and notification publish modes.
• Added MediatorConfiguration, MediatorHandlerConfiguration, and MediatorHandlerKind classes for improved configuration management.
• Implemented MediatorHandlerDescriptor for fluent API in handler configuration.
• Added tests for manual handler registration and dispatching various command, query, and notification types.
• Improved error handling for invalid handler types during registration.

[Copilot]

Pull request overview

This PR refactors Mocha Mediator handler registration to support manual AddHandler<T>() registration alongside source-generated registration, and replaces notification “strategy” types with a runtime NotificationPublishMode option (sequential vs concurrent). It also updates docs, tests, and analyzer snapshots to match the new configuration/registration model.

Changes:

• Introduces descriptor/configuration-based handler registration (MediatorHandlerConfiguration, MediatorHandlerDescriptor, AddHandler<T>()) and updates pipeline building to use per-handler pipelines (especially for notifications).
• Replaces notification strategy services with NotificationPublishMode in MediatorOptions, updating mediator publish behavior and tests accordingly.
• Updates analyzer code generation to emit handler-configuration registrations (and updates snapshots), plus docs/benchmarks/solution file updates.

Reviewed changes

Copilot reviewed 78 out of 78 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
website/src/docs/mocha/v1/mediator/pipeline-and-middleware.md	Updates pipeline/middleware and notification publish mode documentation.
website/src/docs/mocha/v1/mediator/index.md	Documents manual AddHandler<T>() and options; minor wording tweaks.
src/Mocha/test/Mocha.Mediator.Tests/TestSetup.cs	Refactors test service-provider setup to use handler registration APIs.
src/Mocha/test/Mocha.Mediator.Tests/NotificationStrategyTests.cs	Updates tests to use NotificationPublishMode and AddHandler.
src/Mocha/test/Mocha.Mediator.Tests/NamedMediatorTests.cs	Updates named mediator tests to register handlers via AddHandler.
src/Mocha/test/Mocha.Mediator.Tests/MiddlewarePipelineTests.cs	Updates middleware tests to register handlers via AddHandler.
src/Mocha/test/Mocha.Mediator.Tests/MiddlewareFactoryContextTests.cs	Updates middleware factory context tests to use AddHandler.
src/Mocha/test/Mocha.Mediator.Tests/InstrumentationTests.cs	Updates instrumentation tests to use AddHandler.
src/Mocha/test/Mocha.Mediator.Tests/ContextPoolingTests.cs	Updates pooling tests to use AddHandler.
src/Mocha/test/Mocha.Mediator.Tests/AddHandlerTests.cs	Adds coverage for manual handler registration and dispatch.
src/Mocha/test/Mocha.EntityFrameworkCore.Tests/EntityFrameworkTransactionMiddlewareTests.cs	Updates EF transaction middleware tests to use AddHandler.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/WarmUpGeneratorTests.Generate_WarmUpMethod_WithAllHandlerTypes_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/QueryHandlerGeneratorTests.Generate_QueryHandler_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/QueryHandlerGeneratorTests.Generate_MultipleQueryHandlers_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/PartialClassHandlerTests.Generate_PartialVoidCommandHandler_AcrossFiles_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/PartialClassHandlerTests.Generate_PartialQueryHandler_AcrossFiles_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/PartialClassHandlerTests.Generate_PartialClassHandler_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/NotificationHandlerGeneratorTests.Generate_SingleNotificationHandler_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/NotificationHandlerGeneratorTests.Generate_MultipleHandlersForSameNotification_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/NestedHandlerTests.Generate_NestedClassHandler_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/ModuleNameHelperTests.Generate_NullAssemblyName_UsesAssemblyDefault_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/ModuleNameHelperTests.Generate_AssemblyNameWithHyphen_UsesLastSegmentSanitized_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/MixedHandlerGeneratorTests.Generate_HandlersInDifferentNamespaces_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/MixedHandlerGeneratorTests.Generate_AllHandlerTypes_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/MediatorModuleTests.Generate_ModuleFile_ContainsHandlerRegistrations.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/MediatorModuleTests.Generate_DottedAssemblyName_UsesLastSegment.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/MediatorModuleTests.Generate_DefaultAssemblyName_PrefixesWithLastSegment.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/KnownTypeSymbolsTests.Generate_WithAllHandlerTypes_AllSymbolsResolved_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/KnownTypeSymbolsTests.Generate_CommandVoidResolution_ICommandInterface_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/KnownTypeSymbolsTests.Generate_CommandOfTResolution_ICommandGeneric_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/InternalHandlerTests.Generate_InternalHandler_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/GenericHandlerTests.Generate_OpenGenericCommand_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/GenericHandlerTests.Generate_MultipleHandlersSameNamespace_DeterministicOrder_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/ExplicitModuleNameTests.Generate_ModuleWithOnlyName_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/DiagnosticTests.NoWarning_CommandWithHandler_NoDiagnostic.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/DiagnosticTests.MO0004_OpenGenericQuery_ReportsInfo.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/DiagnosticTests.MO0004_OpenGenericCommand_ReportsInfo.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/DiagnosticTests.MO0002_VoidCommandWithTwoHandlers_ReportsError.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/DiagnosticTests.MO0002_CommandWithTwoHandlers_ReportsError.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/CommandHandlerGeneratorTests.Generate_VoidCommandHandler_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/CommandHandlerGeneratorTests.Generate_MultipleCommandHandlers_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/test/Mocha.Analyzers.Tests/snapshots/CommandHandlerGeneratorTests.Generate_CommandWithResponseHandler_MatchesSnapshot.md	Snapshot update for new handler-configuration generation output.
src/Mocha/src/Mocha/Transport/MessagingTransportDescriptor.cs	Updates transport descriptor extension API types (but currently leaves ExtendWith methods as no-ops).
src/Mocha/src/Mocha/Descriptors/MessagingDescriptorBase.cs	Renames descriptor extension interface and updates base implementation.
src/Mocha/src/Mocha/Descriptors/IMessagingDescriptorExtension.cs	Renames/reshapes descriptor extension interfaces.
src/Mocha/src/Mocha/Descriptors/IMessagingDescriptor.cs	Updates descriptor interfaces to return the renamed extension interface.
src/Mocha/src/Mocha.Mediator/Pipeline/TaskWhenAllPublisher.cs	Removes old concurrent notification strategy implementation.
src/Mocha/src/Mocha.Mediator/Pipeline/PipelineBuilder.cs	Replaces “terminal” builders with handler-typed pipeline builders.
src/Mocha/src/Mocha.Mediator/Pipeline/NotificationStrategyFeature.cs	Removes old runtime feature holding INotificationStrategy.
src/Mocha/src/Mocha.Mediator/Pipeline/MediatorPipelineConfiguration.cs	Removes old pipeline configuration model.
src/Mocha/src/Mocha.Mediator/Pipeline/ForeachAwaitPublisher.cs	Removes old sequential notification strategy implementation.
src/Mocha/src/Mocha.Mediator/MediatorRuntime.cs	Adds separate notification pipeline storage and exposes publish mode.
src/Mocha/src/Mocha.Mediator/MediatorOptions.cs	Adds NotificationPublishMode option and enum.
src/Mocha/src/Mocha.Mediator/Mediator.cs	Implements sequential vs concurrent notification dispatch over per-handler pipelines.
src/Mocha/src/Mocha.Mediator/Descriptors/MediatorHandlerDescriptor.cs	Adds fluent handler descriptor with interface-based kind detection.
src/Mocha/src/Mocha.Mediator/Descriptors/MediatorDescriptorBase.cs	Adds shared base for mediator descriptors/extensions.
src/Mocha/src/Mocha.Mediator/Descriptors/MediatorConfigurationContext.cs	Adds internal configuration context for descriptor construction.
src/Mocha/src/Mocha.Mediator/Descriptors/IMediatorHandlerDescriptor.cs	Adds handler descriptor interface.
src/Mocha/src/Mocha.Mediator/Descriptors/IMediatorDescriptorExtension.cs	Adds mediator descriptor extension interfaces.
src/Mocha/src/Mocha.Mediator/Descriptors/IMediatorDescriptor.cs	Adds mediator descriptor interfaces.
src/Mocha/src/Mocha.Mediator/Descriptors/IMediatorConfigurationContext.cs	Adds mediator configuration context interface.
src/Mocha/src/Mocha.Mediator/Descriptors/IHasMediatorConfigurationContext.cs	Adds context marker interface for descriptors/extensions.
src/Mocha/src/Mocha.Mediator/DependencyInjection/MediatorHostBuilderHandlerExtensions.cs	Adds IMediatorHostBuilder.AddHandler<T>() and generator-only configuration hook.
src/Mocha/src/Mocha.Mediator/DependencyInjection/MediatorBuilder.cs	Refactors runtime build around handler descriptors and per-handler notification pipelines.
src/Mocha/src/Mocha.Mediator/DependencyInjection/IMediatorBuilder.cs	Replaces RegisterPipeline with handler registration/configuration APIs.
src/Mocha/src/Mocha.Mediator/Configuration/MediatorHandlerKind.cs	Introduces handler kind enum for configuration.
src/Mocha/src/Mocha.Mediator/Configuration/MediatorHandlerConfiguration.cs	Introduces handler configuration model used by generator/manual registration.
src/Mocha/src/Mocha.Mediator/Configuration/MediatorConfiguration.cs	Adds base configuration with feature extensibility.
src/Mocha/src/Mocha.Mediator.Abstractions/INotificationStrategy.cs	Removes old notification strategy abstraction.
src/Mocha/src/Mocha.Analyzers/Models/MessageKind.cs	Renames void-command kind to Command.
src/Mocha/src/Mocha.Analyzers/Models/HandlerKind.cs	Renames void-command handler kind to Command.
src/Mocha/src/Mocha.Analyzers/Inspectors/MessageTypeInspector.cs	Updates kind inference for ICommand messages.
src/Mocha/src/Mocha.Analyzers/Inspectors/HandlerInspector.cs	Updates kind inference for void command handlers.
src/Mocha/src/Mocha.Analyzers/Generators/DependencyInjectionGenerator.cs	Updates generator to emit handler configuration registrations.
src/Mocha/src/Mocha.Analyzers/FileBuilders/DependencyInjectionFileBuilder.cs	Rewrites generated output to use AddHandlerConfiguration + new pipeline builders.
src/Mocha/benchmarks/Mocha.Mediator.Benchmarks/Program.cs	Updates benchmark target to net10.0 toolchain settings.
src/Mocha/benchmarks/Directory.Packages.props	Adds central BenchmarkDotNet version for benchmarks.
src/Mocha/Mocha.slnx	Adds mediator/analyzer projects to the solution listing.

Comments suppressed due to low confidence (1)

src/Mocha/src/Mocha/Transport/MessagingTransportDescriptor.cs:247

• ExtendWith(...) currently ignores both the configure delegate and the state parameter, returning this without applying any configuration (and without null-checking). This will silently drop transport extensions that rely on this overload.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (64dcf22) to head (5c8b9c7).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@     Coverage Diff      @@
##   main   #9452   +/-   ##
============================
============================

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.