use crate*;
/// Query the _headers_ of a remote agent's chain.
///
/// The agent activity is only the headers of their source chain.
/// The agent activity is held by the neighbourhood centered on the agent's public key, rather than a content hash like the rest of the DHT.
///
/// The agent activity can be filtered with [ `ChainQueryFilter` ] like a local chain query.
/// Walks the source chain in reverse (latest to oldest) filtering by header and/or entry type
///
/// Given a header and entry type, returns an [ `Vec<Element>` ]
///
/// @todo document this better with examples
/// @todo do we want to return elements rather than hashes?
/// @todo implement cap grant/claim usage in terms of query