Default Mediator configuration break Scoped services

[Pycnomerus]

Describe the bug
when using the library default, if you register anything that will be used by a command as scoped.
the application crash. with an impossible to resolve configuration error.

this will probably also break typed httpclient.

To Reproduce
Steps to reproduce the behavior:
when using mediator default registration
register a scoped service.
try to use it inside any IRequest object.

Expected behavior
all type of scopes registration should work without changing the default behaviour.
this is especially a concern since it's not an expected behavior, and introduce risk namely to use Typed HttpClient

Screenshots

Additional context
here's a test sample project to reproduce

[meziantou]

The workaround is to set the lifetime to Scoped instead of the default Singleton

builder.Services.AddMediator(configure => configure.Lifetime = ServiceLifetime.Scoped, typeof(Program).Assembly);

It would be nice to re-evaluate the default Lifetime value. It has been set to Singleton for performance reasons. I'm not sure how many projects would be impacted by this change.

[gowon]

I just ran into this same issue. It looks like as of this commit, the MediatR project defaults MediatRServiceConfiguration.Lifetime to Transient. Maybe this package should also default to Transient to keep those expectations consistent?