| n4ds_abi_version | The C ABI version string. |
| n4ds_fetch | Download + SHA-256-verify a resolved dataset into the cache (JSON status string). |
| n4ds_resolve | Resolve a dataset id against an index JSON into its download contract (JSON string). |
| n4ds_verify_cached | Re-verify a cached dataset directory against the contract's SHA-256s (JSON report). |