* With WatchBookmark feature, clients are able to request watch events with BOOKMARK type. Clients should not assume bookmarks are returned at any specific interval, nor may they assume the server will send any BOOKMARK event during a session.

- Implemented API streaming for the `watch-cache`
  
  When `sendInitialEvents` `ListOption` is set together with `watch=true`, it begins the watch stream with synthetic init events followed by a synthetic "Bookmark" after which the server continues streaming events. ([#110960](https://github.com/kubernetes/kubernetes/pull/110960), [@p0lyn0mial](https://github.com/p0lyn0mial))
- Introduced API for streaming.
  

- The synthetic "Bookmark" event for the watch stream requests will now include a new annotation: `kubernetes.io/initial-events-list-blueprint`. THe annotation contains an empty, versioned list that is encoded in the requested format (such as protobuf, JSON, or CBOR), then...

- Implemented API for streaming for the `etcd` store implementation.
  When `sendInitialEvents ListOption` is set together with `watch=true`, it begins the watch stream with synthetic init events followed by a synthetic `Bookmark`, after which the server continues streaming events. ([#119557](https://github.com/kubernetes/kubernetes/pull/119557), [@p0lyn0mial](https://github.com/p0lyn0mial))

- Removed the `kubernetes.io/initial-events-list-blueprint` annotation from the synthetic "Bookmark" event in watch stream requests. ([#132326](https://github.com/kubernetes/kubernetes/pull/132326), [@p0lyn0mial](https://github.com/p0lyn0mial))

- Client-go/reflector: warns when the bookmark event for initial events hasn't been received ([#124614](https://github.com/kubernetes/kubernetes/pull/124614), [@p0lyn0mial](https://github.com/p0lyn0mial)) [SIG API Machinery]