Trace an error route

Select the failed Execution and read its stage and route:

• the command-registration handler can mark the error handled;
• otherwise the error continues to the shared UseCase.onError hook;
• an unhandled error may then reach the Snapshot stream;
• the terminal Entry records failure independently of how UI reports it.

Do not infer the source from a stack trace alone. Match the Execution ID, Command type, error stage, and handler route. If values are hidden, expose only the smallest safe diagnostic representation needed to distinguish the case.

An error in diagnostic encoding is isolated and is not a business Command failure.