Sounds like an invasion of privacy and violation of the "secret ballot" principle to me!
Furthermore, since Texans are registered by party affiliation, this is tantamount to an early release of election results.
Is this actually legal?
No, they are not. That is just not a true statement. They do keep track of what primaries you vote in, and if you vote in a partisan primary, you can't change parties for any run-off, but you get a clean voter registration card every two years.
How so? Who voted has always been a public record. In no way does it show HOW you voted.
Furthermore, since Texans are registered by party affiliation, this is tantamount to an early release of election results.
News to me. I'm 55 and have voted in Texas since I was 21, even when I lived overseas and have NEVER registered with a party. Fact is there is no way in this state to do that. Your vote in a primary determines your party but other than runoffs you can switch back and forth as you wish.