finding: two consumer-local structural DataEngineLike re-declarations remain after the #11493 deletion (datasource-admin-plugin, service-analytics) #11833

Found while carrying out #11493 (which deleted service-datasource/src/plugin.ts's structural DataEngineLike per the maintainer ruling there). Filed unassigned as an observation, measured at eab6d131b.

The observation

Two more consumer-local structural engine types survive in-tree, same pattern the #4251 B3 sweep replaced with declared contract members ("seven consumer-local surface declarations"):

• packages/services/service-datasource/src/datasource-admin-plugin.ts (~line 44) — DataEngineLike declaring registerDriver? / registerDatasourceDef? / getDriverByName? plus all-optional sys_metadata CRUD (findOne/find/insert/update/delete) used for hot pool (de)registration and durable datasource-record persistence.
• packages/services/service-analytics/src/plugin.ts (~line 19) — DataEngineLike declaring aggregate (with the engine.aggregate: add per-aggregation filter to the contract — ruled half of #10413 (measure-level filters on the ObjectQL analytics path) #10576 per-aggregation filter) and execute for the analytics bridge.

What was verified (and what was not)

• Every member checked resolves to a REAL engine member: registerDatasourceDef exists on ObjectQL (packages/objectql/src/engine.ts, registerDatasourceDef(def: …): void), registerDriver/getDriverByName are on the contract/engine, and the CRUD members exist on IDataEngine. Unlike the getDatasourceDriver? member The engine-registration path is still unreached by the introspection compile channel: IDataDriver declares no introspectSchema, and IDataEngine.introspectDatasource() returns Promise<unknown> #11493 deleted (zero references outside its file, a probe no engine ever matched), no dead member was found here — this is a pattern observation, not a measured defect.
• NOT verified: whether the loosened signatures these local types declare (all-optional CRUD, narrowed option bags) are each still assignable-compatible with the current IDataEngine/IObjectQLEngine members they shadow — that is exactly the drift the The service-lookup any rule misses getService<any>(...) — 80 sites erase the slot contract, 3 of them inside the rule's own scope #4251 contract exists to prevent, and nothing compiles these local declarations against the real engine.

Why it may deserve a card (and why not now)

The #11493 four-facet reasoning applies one seam over: a private structural type meets no compiler on the producer side, so engine-surface drift lands silently in the consumer. But both sites are deliberate graceful-degradation seams (absent members degrade to in-memory / reduced capability), and moving them to Partial<IObjectQLEngine>-style derived types or new optional contract members is a design decision with its own blast radius — needs its own pass, not a rider.

Refs: #11493 (the ruling + the deleted third instance) · #4251 (B3 — the declared-contract sweep this pattern predates/escaped).