ConstReadonlyBadGateway: 502HTTP 502 — transient upstream failure. Eligible for retry on GET.
ReadonlyBadRequest: 400HTTP 400 — how Gizwits reports an invalid or expired user token (error code 9004 in the body), not 401. Triggers session re-auth alongside HttpStatus.Unauthorized.
ReadonlyGatewayTimeout: 504HTTP 504 — transient upstream timeout. Eligible for retry on GET.
ReadonlyServiceUnavailable: 503HTTP 503 — transient service unavailability. Eligible for retry on GET.
ReadonlyUnauthorized: 401HTTP 401 — authentication required or rejected. Triggers session re-auth.
HTTP status codes used across the SDK. Single source so callers don't redefine them per file.
Restricted to the codes the SDK actually branches on — adding more here without a real call site is dead weight.