postgres_reliable_reporting_service always builds the base ReliableReportingService, so adopters can't use a subclass #1588

Observed

ReliableReportingService.memory(...) constructs cls, so an adopter's subclass gets an in-memory service of its own type. adcp_reporting_storage.postgres_reliable_reporting_service(...) replaced ReliableReportingService.postgres(...) in 9.0.0 (#1557), and it always constructs the base ReliableReportingService:

from psycopg_pool import AsyncConnectionPool

from adcp.reporting import ReliableReportingService
from adcp_reporting_storage import postgres_reliable_reporting_service


class HostReportingService(ReliableReportingService):
    async def get_reporting_status(self, request, context=None):
        ...  # host-specific error translation / alerting


def account_context(*_args, **_kwargs):
    raise NotImplementedError


memory = HostReportingService.memory(account_context=account_context)
pg = postgres_reliable_reporting_service(
    pool=AsyncConnectionPool("postgresql://unused", open=False), account_context=account_context
)
print("memory():", type(memory).__name__)
print("postgres_reliable_reporting_service():", type(pg).__name__)

With adcp 9.0.0 and adcp-reporting-storage 0.1.0b1 (built from the #1571 branch):

memory(): HostReportingService
postgres_reliable_reporting_service(): ReliableReportingService

Expected

The PostgreSQL factory can build an adopter's subclass, as memory() and the 9.0 betas' ReliableReportingService.postgres() classmethod could. For example, a service_class: type[ReliableReportingService] = ReliableReportingService keyword.

Impact

install() routes the reporting tools to the service's methods, so overriding them on a subclass is how a host translates errors and adds alerting around get_reporting_status, sync_reporting_status and get_revision_content. Without a way to pick the class, the Embedded Sales Agent copies the factory body: it builds PgReportingLedgerStore, PgReportingStagingStore and PgReportingSealStore and passes staging=, seals= and initialize_source_storage= itself. That copy silently drifts whenever the factory gains a store, for example when production= composes PgReportingProductionStore.

Found while moving the Embedded Sales Agent from 9.0.0b4 to 9.0.0. Since adcp-reporting-storage hasn't had its first release yet, this could land before 0.1.0b1 publishes.