Source: src/firebird/driver/provider.py, relative to the repository root.
FirebirdProvider is a structural protocol. External runtime packages can satisfy it without
inheriting from the driver. _DriverProvider is private and handles explicit client paths or
system client lookup. Its root, client version, and capabilities are initialized from the loaded
client API by the interfaces.py API-loaded hook. They must not be read before that step.
The runtime root comes from IConfigManager.get_root_directory(), not from the client filename.
The private provider checks that root's plugins directory for a numbered engineXX shared
library to determine whether the embedded capability is present. External provider metadata
is not changed by the driver.
firebird_log is an optional local path in the public protocol. The private driver provider
returns None because a client library does not identify the log of the server it connects to.