Artifact schema

File	Cardinality	Role	First debugging use
run.json	one per run	resolved identity, configuration, and provenance	confirm what actually ran
cases.jsonl	one row per case	inputs, outputs, labels, decisions, and case evidence	inspect a surprising example
events.jsonl	many ordered events	runtime transitions and observations	find the earliest failed stage
metrics.json	one per run	aggregate results derived from cases	identify/recompute a reported score

Fields may evolve during the source-preview phase. Consumers should validate the schema/version carried by artifacts, preserve unknown fields when safely round-tripping, and avoid joining files by line number when explicit identifiers exist.