Function min_protocol_version 

pub const fn min_protocol_version(network: Network) -> u32

Per-network default seed used only when an unpinned SDK has no explicit initial version.

Mainnet, testnet and regtest seed at protocol version 13, the lowest version any of those networks still runs. Devnets seed at 14: they are cut from the current development line. Proved reads can use a newer version named in their signed response metadata even when the SDK starts with a lower seed; the stored version ratchets only after proof and signature verification.

Not a runtime clamp: SdkBuilder::with_initial_version can seed an unpinned SDK below this value (no construction-time floor), and auto-detect (Sdk::maybe_update_protocol_version) only ratchets the stored version upward via fetch_max when the network reports a newer one.