Placement prepares outside a transaction and commits in one

Context

Placement needs authoritative seller preparation and scarce-resource protection without holding locks during remote calls.

Decision

Separate remote preparation from the database commit. Application-published claim functions join the placement transaction in a consistent order.

Alternatives Considered

Keeping a transaction across remote requests extends lock duration. Independently committed claims would instead require a reliable release mechanism after placement failure.

Consequences

Applications must publish executable claim functions. Billing and leased-resource confirmation remain separate after-commit work with their own recovery.