0347 — Missing or mismatched schema surfaces as teaching errors, not raw Postgres errors

Context. A caller who skips bootstrap, or runs a binary against a database migrated past (or short of) what it was compiled for, would otherwise hit a raw 42P01 (undefined table) from deep inside some query — accurate but useless for diagnosis. Dated approximately; built across July 2026.

Decision. RegisterTopic gates on the system being registered, raising an error that wraps migrate.ErrNotRegistered instead of leaking 42P01. Lifecycle AssertSchemaSupported fails a producer/consumer fast when the database’s schema version is outside the range the binary compiled against. The CLI’s translateAdminError turns a raw 42P01 into “run vulkan migrate init first.”

Consequences. Every schema-state failure is caught at a named gate with a wrapped sentinel a caller can match on, and the failure names its remedy. The cost is a pre-flight check on registration and lifecycle startup paths.