bitcoin core – How do miners manually add transaction to a block template?

1. Does it work one thing like this?

No, not likely.

generateblock is a testing solely RPC that truly mines a block utilizing the interior CPU miner, itt doesn’t make a block template. So it is utterly irrelevant to this.

There are principally two methods of inserting a transaction:

1. The miner would put the transaction in their very own mempool (and probably find yourself broadcasting it) through the use of sendrawtransaction. Then they might use prioritisetransaction to artificially set the transaction’s payment so that it’s going to seem in a block template generated by getblocktemplate.
2. They’re utilizing some exterior block template generator that can do the insertion itself. This software program might start with a block template created by getblocktemplate, but it surely must additionally implement loads of the block meeting code itself to confirm that the template it finally ends up producing is legitimate.

2. I think about the node software program is consistently updating the block to maximise the quantity of charges acquired. Does it imply it overrides the transaction I added manually?

In the event that they used technique 1, no there wouldn’t be any overriding of the guide transaction since bitcoind remembers the modified payment and can proceed to account for it till that transaction is confirmed.

For technique 2, the exterior template software program is doing the insertion so it would bear in mind. That exterior software program might even be (re)constructing the template anyhow, so it is principally what bitcoind is doing in technique 1.

3. Is there some UI that lets you do that? E.g. shows the present block template + transactions in mempool and lets you substitute transaction in a block template with transaction from the mempool? If not, I’d try to construct one thing in that style.

I do not assume there are any such software program that’s publicly accessible. Lately, block templates are produced by swimming pools, and these swimming pools usually use customized software program, so they could have tooling that does this. However it will not be accessible to the general public.