List-Watch pattern

As documented in section "Efficient detection of changes" in kubernetes reference, we can use the resourceVersion from a list response in a subsequent watch request, to reliably receive changes since the list operation. In lightkube this information is available on the object returned from list():

seen_pods = {}
async for pod in (podlist := client.list(Pod)):
    seen_pods[pod.metadata.name] = pod
async for event, pod in client.watch(Pod, resource_version=podlist.resourceVersion):
    match event:
        case "ADDED" | "MODIFIED":
            seen_pods[pod.metadata.name] = pod
        case "DELETED":
            del seen_pods[pod.metadata.name]

Note that the field resourceVersion is only available after iteration started, and will raise lightkube.NotReadyError if it is accessed before iterating the result.