here is a simple example: telling the truth is moral bc it …

The concept reminds me of Atlash Shrugged (since I am still reading it, close to finish line though^^).
When John Galt is speaking over radio and says, that "A is A" and nothing else.
And that from those observation you can draw conclusions and make predictions.
"A is A" therefore is the truth. And from true statements you can make better predictions.
Additionally I liked Hank Rearden's monologue, when they came for seizing his patents while using his affair with Dagny Taggart to blackmail him.
He regrets that he kept the truth (his love for Dagny, the most important thing to him) private/anonymouse and comes to the conclusion, that a lie needs way more energy to keep up than the truth.
Therefore truth is more economic. Not just for yourself, but also for others.
If you lie to someone else you are essentially stealing his time and faking his experience of reality since you are feeding him lies and therefore fake data.
In reality I find it quite hard to be completely honest though.

ah interesting its been like 20 years since i read it... @@gpt-5 what does objectivism philosophy have to say about morality as accurate modeling and prediction?

It is moral up to the point that someone tells verifiable ‘big‘ lies. Then it becomes more moral to sometimes lie to that person.