The legacy entity event mappings remain

One event source carries two mapping APIs. register_mapping<Event> takes the entity name and the channel and publishes an event built from the notification's timestamp, the changed ids and the tenant. register_entity_event_mapping<Event> takes only the channel and lets the event's own traits convert the whole notification, key record included, into the event the model specifies. The second is the one the codegen emits per entity; the first is the older hand-written shape.

Both work: since the event source parses the trigger's notification once and converts it for the older API, a channel registered either way receives its events. The older API is now a compatibility surface that 118 of the 275 mapping registrations still use: 53 in trading, 14 in dq, 9 each in synthetic and reporting, 5 each in marketdata and analytics, 2 in ore, and one each in workspace, refdata and compute. Migrate the registrations to the generated canonical registrars, then delete the older API, channel_entities_ and the conversion branch in the listener.

Two APIs for one job means every reader has to know which one a channel uses and why. The older API also cannot express a key: it hands a subscriber a timestamp, a list of ids and a tenant, so an event that needs its key record has to be re-read or re-derived, while the canonical event carries it. The conversion in the listener is the load-bearing seam that keeps the older callers alive, and it is the code the 2026-09-26 compute outage ran through: the compute service registered the older API while the trigger published the canonical payload, and every host, batch and workunit notification was dropped until the listener was taught to convert. Deleting the older API removes the choice that caused it.

• projects/ores.eventing/core/include/ores.eventing.core/service/postgres_event_source.hpp — both mapping APIs, channel_entities_, entity_event_mappings_.
• projects/ores.eventing/core/src/service/postgres_event_source.cpp — the listener's conversion for the older mapping.
• projects/ores.compute/service/src/app/application.cpp — migrated to the generated canonical registrars, with one older mapping kept for the dispatch seam, which needs the tenant and the changed ids.
• projects/ores.codegen/ — emits register_<entity>_event_mapping per entity model.

• Run a compute job end to end — the run whose silent outage the two mapping APIs produced.