Type Alias DefinitionInUseBlocker

DefinitionInUseBlocker:
    | { instanceIds: string[]; reason: "non-terminal-instances" }
    | {
        reason: "spawn-referrers";
        referrers: { definition: string; version: number }[];
    }

What blocks a deleteDefinition, so a consumer can render the remediation: abort-in-place via cascade, or delete/redeploy the referrer first.