ADR-0087 exemption (no-migration-prescription): A DDL-emission scope narrowing plus one added client spelling, both inside `driver-sql`. No spec schema, no authorable metadata key and no runtime interface is removed, renamed or re-shaped: the value that decides the outcome is a datasource's knex `client`, which lives in deployment configuration rather than in any stored `sys_metadata` document, so `objectstack migrate meta` has nothing to rewrite and there is no tombstone to project. The channel that reaches an affected deployment is the refusal itself — raised at the DDL gate, before any statement is issued, naming the supported clients and the `skipSchemaSync` posture — and choosing between "move this datasource to a supported database" and "manage its schema out-of-band" is a deployment decision no migration entry can make on an operator's behalf. `pgnative` is a widening and needs no upgrade action at all.