The capacity to include your own judgement in a choice, act on what you know without demanding perfect certainty, and revise when new information arrives.
Self-trust & agency is the capacity to let your own perception, values and judgement participate meaningfully in what you do.
Self-trust is not the belief that you will always be right. Agency is not total control. Both become more practical when you can choose, observe what happens and revise without treating revision as proof that the original choice was a failure.
You do not need perfect certainty to become a participant.
This capacity includes authentic choice and, in a different context, receiving success: allowing something wanted to arrive without immediately handing authority back to an imagined judge.