Should the public API include Codable types?

[jakepetroules]

The following types conform to Codable:

• ProcessIdentifier
• TerminationStatus
• ExecutionResult (conditionally)
• CollectedResult (conditionally)

This seems like a surprising thing to forever commit to as part of the public API. Should we reconsider whether these protocol conformances should be present before the 1.0 release? It's unclear to me what the value persisting these types would be.