0549 — worker.Definition becomes data; the concrete machines are *Provisioner

Context

[0547] rejected a concrete Definition/Provisioner split for lacking a consumer. The user reopened it: code should match the mental model — a Provisioner provisions a Definition. Survey found the consumer [0547] missed: 8 of 10 kinds’ Declare bodies were the identical ValidateOwner+RegisterWorker boilerplate over four data points, and the manager already hands Provision the declared row in pieces.

Decision

Narrows [0547]: the *Instance rename stands; the no-split clause flips.

• worker.Definition is a data struct — Name, Metadata, OwnerKind ("" = any kind may declare one; the manager’s case), TargetInstances (0 -> 1). The lifecycle reads: Definition -> declared as a worker row -> provisioned into an Instance -> Run.
• WorkerController.DeclareWorker(definition, owner) is the one row-write verb: owner-kind guard + RegisterWorker. Every kind’s Declare ends here.
• Concrete *XDefinition machines are renamed *XProvisioner; each builds its Definition in its constructor and stores it. Provisioner interface: Definition() *Definition (replaces Name) and Provision(ctx, declared *worker.Worker) (replaces the id/owner/metadata triple — the row IS the declared definition).
• Declarer stays universal — the 8 data kinds’ Declare is the one-liner through DeclareWorker (consumers inherit it from BaseProvisioner, which stamps NoInstanceTarget as a base invariant); the alerts keep their behavioral preamble (group + binding + owner mint) ending in the same verb. The Declarer+Provisioner bundle interface is deleted.
• Declare returns only error: provisioning always reads the row fresh (newest declaration wins); a returned row would be a stale second carrier.

Consequences

• Labs that overrode metadata at Provision now set row.Metadata before the call. K8s spec-vs-object is the precedent for the Definition/Worker pair.
• The alerts’ Declare preamble is them hand-rolling consumer registration — a candidate post-v1 cleanup, out of scope here.

Amended. [0639] narrows the clause “consumers inherit it from BaseProvisioner, which stamps NoInstanceTarget as a base invariant”: each consumer kind now passes the target to NewDefinition and the base guards it, rather than the base mutating the definition. The invariant stands; the rest of this record stands.