cursor_integrity_invalid· code· HTTP 400· scope endpointCursor integrity check failed for the v1 stateful opaque handle (client-sync §12.1, canonical body `{v, purpose, issued_at, expires_at, h}`): the `h` handle is unknown / revoked / expired / cross-bound, or its stored binding (principal, device, service, filter_digest, purpose) does not match the authenticated request. Distinct from cursor_expired (TTL) and cursor_unrecognized (cross-service portability miss). Client MUST clear local cursor cache and restart from initial /account/subscribe.