Function containers_clear_document 

pub fn containers_clear_document(outcome: &ClearOutcome, dry_run: bool) -> Value

devp caches clear <engine> --json: what was run, and what the disk gave back.

freed_bytes is the engine’s own system df total before minus the same total after, never the sum of what each prune command reported. Container layers are shared, so those add up to more than the disk ever had — a consumer adding the step figures would get a number that cannot be true.

volumes_untouched is stated rather than implied. It is the one promise this command makes about what it did not do, and a consumer should be able to check it without reading the argv table in the binary.