How does confd handle migration of yang modeled data across software versions

say in my new release I would like to add a new leaf / change the type of a leaf element .?
what are the steps done by confd to migrate the paramters,
Further if i like to tweak the behaviour of the migration , is there c-api 's for the same …

There is an entire chapter called In-service Data Model Upgrade in the ConfD User Guide that addresses this topic. There are C APIs that allow user code participation during the upgrade process.

hey waitai ,
thanks will check it out