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1. When the consumer needs to reset offsets, it uses the ListOffsets API to query the leader. To avoid querying stale leaders, we will add epoch fencing. Additionally, we will modify this API to return the corresponding epoch for any offsets looked up.
2. We will also provide the leader epoch in the offset commit and fetch APIs. This allows consumer groups to detect truncation across rebalances or restarts. Note that in cases like that found in KIP-232, it is possible for the leader epoch included in the committed offset to be ahead of the metadata that is known to the consumer. Consumers are expected to wait until the metadata has at least reached the epoch of the committed offset before checking for truncation.
3. For users that store offsets in an external system, we will provide APIs which expose the leader epoch of each record and we will provide an alternative seek API so that users can initialize the offset and leader epoch.

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