@ezpublish.api.persistence_handler is badly name, and doesn't reflect the actual service. There is also an @ezpublish.api.storage_engine, used internally, that isn't an API service.

Storage engine used by persistence, aka the current storage engine

• Rename @ezpublish.api.storage_engine => @ezpublish.spi.persistence.storage_engine
• Add services for @ezpublish.spi.persistence.storage_engine.(location|content|...)_handler (aliases ?)

Persistence handler used by the repo

This is what users would use to inject the persistence layer into their own code:

• Rename @ezpublish.spi.persistence_handler to @ezpublish.spi.persistence
• Add services for @ezpublish.spi.persistence.(location|content|...)_handler