CompanionError.code values: the server vocabulary (COMPANION_ERROR_CODES,
drift-tested against api-error.ts) plus the SDK-synthesized ones — DERIVED
from those runtime lists rather than hand-retyped, so a new code can never
silently miss this union again (the old copy had drifted 5 codes behind).
The (string & {}) arm keeps the type open for codes newer than this SDK
build while preserving autocomplete.
CompanionError.codevalues: the server vocabulary (COMPANION_ERROR_CODES, drift-tested against api-error.ts) plus the SDK-synthesized ones — DERIVED from those runtime lists rather than hand-retyped, so a new code can never silently miss this union again (the old copy had drifted 5 codes behind). The(string & {})arm keeps the type open for codes newer than this SDK build while preserving autocomplete.