ADR-0009: Independent Work Plane with local Runtime dispatch

Decision

Add Agentstration.Work as a framework-neutral domain boundary. It owns WorkItem, controlled lifecycle transitions, functional history, interactions, results, errors, and idempotent application of Runtime events. Public DTOs, storage, and transport remain separate.

The Work Plane delegates through IWorkExecutionGateway. Standalone mode implements this port in Agentstration.Runtime.Local with a bounded local queue and a hosted adapter. Work snapshots use an independent SQLite store with optimistic version concurrency.

Consequences

The Work Plane does not reference Microsoft Agent Framework, a model provider, Runtime implementation, ASP.NET Core, or EF Core. The local adapter is executable offline but does not recover queued messages after process failure. A durable connector can replace it without changing the aggregate or canonical /api/work/workitems contracts.