Optional ReadonlyreasonAn optional machine-readable reason, rendered into the response body alongside the message. DECLARED HERE rather than sniffed structurally at the mapper so the channel is part of the contract a subclass opts into, and so the mapper needs no import of any subclass to render it (see the header for why that import must not exist).
ReadonlystatusThe response status. 4xx/5xx only — see doErrorResponse.
A request refused at the thread DO's identity boundary: the DO's name is unresolvable, or the request carries no valid execution principal. Surfaced as 403 — this boundary is internal (a DO namespace is not client-reachable and the Worker validates the threadId before forwarding), so there is no existence oracle to protect here and a distinct status keeps a routing bug from reading as a generic 500.
Extends DoStatusError because that is how a status opts in: this class is what doErrorResponse recognizes, not the shape of its fields.