Append Workspace County

Load status for a workspace-county pair.

Lifecycle: provisioning (initial — set by workspace standup before the Neon project is ready) → pending (set by provision_workspace_op after schema apply succeeds; the pickup sensor's gate value) → loading (set by sandbox_load when it starts writing for one county) → succeeded | failed (terminal, set by the asset's try/finally). provisioning and the mid-load loading were previously the same value; MAIA-2309 split them so the lifecycle reads literally instead of overloading loading across two phases.

canceled is the admin-initiated terminal state: an in-flight (pending/loading) row canceled before the load finished. The Dagster stamps are status-guarded so a canceled row is never resurrected by a run that was already queued; retry via the reload seam re-queues it.

inherited sits outside that lifecycle: the county's data arrived with the workspace's Neon branch and no load ever ran for this workspace. A self-serve workspace is a copy-on-write fork of a prepared parent, so its counties are queryable the moment the branch exists. The distinction from succeeded is what a future refresh needs — re-forking from a refreshed parent carries inherited counties for free and drops separately loaded ones, and without the distinction a refresh either reloads everything or silently loses the one-offs.

A producer writing this status should stamp data_loaded_at with the fork time in the same statement. Access does not depend on it — the reload seam backstops a missing value with now(), so an unstamped inherited row keeps its access through a refresh — but the backstop records when someone first refreshed the county rather than when its data actually arrived, and that column is what a later refresh reads to tell inherited data from data loaded afterwards.