The app process a request ran in, as an opaque value. A platform's app layer
installs its own subclass (it knows its process's services; this neutral
layer knows none of them), and the transport attaches the value to the
failures that continue in the same process — a checkpoint, whose challenge
the platform opens as screens of that process (OpenChallenge(error) on
Android). Core only carries it: it never reads it. It is opaque: a caller
has nothing to do with it.
The app process a request ran in, as an opaque value. A platform's app layer installs its own subclass (it knows its process's services; this neutral layer knows none of them), and the transport attaches the value to the failures that continue in the same process — a checkpoint, whose challenge the platform opens as screens of that process (
OpenChallenge(error)on Android). Core only carries it: it never reads it. It is opaque: a caller has nothing to do with it.