optional bool watch = 3;

  // allowWatchBookmarks requests watch events with type "BOOKMARK".
  // Servers that do not implement bookmarks may ignore this flag and
  // bookmarks are sent at the server's discretion. 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.
  // If this is not a watch, this field is ignored.
  // +optional

    * 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.

### Beta

- Promote WatchBookmark feature to beta and enable it by default.
  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. ([#79786](https://github.com/kubernetes/kubernetes/pull/79786), [@wojtek-t](https://github.com/wojtek-t))

- 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.
  

- 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))

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- The metrics `etcd_request_duration_seconds` and `etcd_bookmark_counts` now differentiate by group resource instead of object type, allowing unique entries per `CustomResourceDefinition`, instead of grouping them all under `*unstructured.Unstructured`. ([#112042](https://github.com/kubernetes/kubernetes/pull/112042),...

* Introduce API for watch bookmark events. ([#74074](https://github.com/kubernetes/kubernetes/pull/74074), [@wojtek-t](https://github.com/wojtek-t))
    * Introduce Alpha field `AllowWatchBookmarks` in ListOptions for requesting watch bookmarks from apiserver. The implementation in apiserver is hidden behind feature gate `WatchBookmark` (currently in Alpha stage).

- Try to send watch bookmarks (if requested) periodically in addition to sending them right before timeout ([#90560](https://github.com/kubernetes/kubernetes/pull/90560), [@wojtek-t](https://github.com/wojtek-t)) [SIG API Machinery]