However, if RDTS doubles down on their minority chaintip
I think the if is hardcoded to a block height / flag day, so this is not a question of if or even when anymore. It's a question of "what now"?
invalidating the first block of that branch
The one that applies to forking rules, yes.
I just re-read #5316 - must have been 11 years since I read that ugh - and now I think I'm confused about the mechanism. I remember that at one point the consensus was that invalidateblock would tag a block to lose to a competing block of lower weight, but now I am uncertain of where I read that.
No, invalidateblock causes your node to treat the passed block as invalid. Naturally, any blocks succeeding it are therefore also treated as invalid. And IIRC, we ban peers that send us invalid blocks, so you also get rid of your RDTS peers all in one go.
I think the if is hardcoded to a block height / flag day, so this is not a question of if or even when anymore. It's a question of "what now"?
The one that applies to forking rules, yes.
I just re-read #5316 - must have been 11 years since I read that ugh - and now I think I'm confused about the mechanism. I remember that at one point the consensus was that
invalidateblockwould tag a block to lose to a competing block of lower weight, but now I am uncertain of where I read that.