Package relay

Package Relay is a long-discussed concept and, at the time of writing, is a work in progress in Bitcoin Core. A significant portion of the project involves changes to mempool validation, which glozow describes in her gist Package mempool accept.

PR#20833 added the ability for mempool validation to assess a set of dependent transactions and enabled the testmempoolaccept RPC to support multiple transactions.

PR#21800 added the ability to analyse and limit the ancestor and descendant sets of packages in relation to the mempool.

PR#22674 defined child-with-unconfirmed-parents packages and enabled submission of such packages to the mempool.

These PRs were also accompanied by several refactoring efforts: PR#21062, PR#22796, PR#22675, PR#22855, PR#23381.

The document doc/policy/ contains current information on the stated package acceptance rules.