I am working on a Sitecore Commerce 10 released recently and come across issue whilst generating a Service proxy for custom plugins. Screens attached are example. I have created 2 plugins "Sitecore.Commerce.Plugin.Product" and "Habitat.Commerce.Plugin.Rewards". These projects are created as per the details provided in Sitecore doc site.
These plugins are included in Engine and published for updating proxy. After updating proxy in the CommerceShops.cs I can see the definition created for the plugin which starts with "Sitecore*" i.e. "Sitecore.Commerce.Plugin.Product" for Entities, Commands, Models and Components but for "Habitat.Commerce.Plugin.Rewards", definitions for only Entities are create under this namespace. All other plugin elements i.e. componets, model etc are created under "Sitecore.Commerce.Engine" namespace.
I could only conclude that the Plugin that starts with "Sitecore*" are able to generate definitions for all/required elements in plugin.
Have you come across this issue and managed to resolve this issue. If you need more info please ask.