Function pd_storage_key 

#[unsafe(no_mangle)]
pub extern "C" fn pd_storage_key(
    meta_ptr: *const u8,
    meta_len: u32,
) -> u64

meta as in pd_new_document; returns the legacy SHA-pinned localStorage key string. Pages now key state by the content-fingerprint review_id and call this once to migrate pre-review_id state.