Struct SyncConfig 

pub struct SyncConfig<D: Digest> {
    pub config: Config,
    pub range: Range<Position>,
    pub pinned_nodes: Option<Vec<D>>,
}

Configuration for initializing a journaled MMR for synchronization.

Determines how to handle existing persistent data based on sync boundaries:

• Fresh Start: Existing data < range start → discard and start fresh
• Prune and Reuse: range contains existing data → prune and reuse
• Prune and Rewind: existing data > range end → prune and rewind to range end

Fields

config: Config

Base MMR configuration (journal, metadata, etc.)

range: Range<Position>

Sync range - nodes outside this range are pruned/rewound.

pinned_nodes: Option<Vec<D>>

The pinned nodes the MMR needs at the pruning boundary (range start), in the order specified by nodes_to_pin. If None, the pinned nodes are expected to already be in the MMR’s metadata/journal.