Questions about Cache co-processor with TIDB instance

Going through cache co-processor from here Coprocessor Cache | PingCAP Docs, is there any more documentation which we can refer.

If the cache is not distributed to tidb, what are the strategies for query to tidb stickiness?
Or can we make this distributed by adding redis or hazelcast in the first place?

I believe this would LRU only, if not invalidated by timestamps from TiKV. Or is it going to be a FIFO cache.

Is there any query hints we can pass to make output cachable/non-cachable?

Related issue/PR is here: [proposal] DistSQL Cache on TiDB · Issue #9336 · pingcap/tidb (github.com)

The RFC is here: rfcs/0048-coprocessor-cache.md at master · tikv/rfcs (github.com)

“Is there any query hints we can pass to make output cachable/non-cachable?”

No, not yet support