Yes, but if the probability is much smaller than, say, being hit by a meteorite, then engineers usually say that that's ok. See also hash collisions.
How do you drive the probability of some series of tokens down to some known, acceptable threshold? That's a $100B question. But even if you could - can you actually enumerate every failure mode and ensure all of them are protected? If you can, I suspect your problem space is so well specified that you don't need an AI agent in the first place. We use agents to automate tasks where there is significant ambiguity or the need for a judgment call, and you can't anticipate every disaster under those circumstances.
You’re absolutely right the probability is low. According to my calculations, you’re more likely to get struck by lightning twice on the same day and drown in a tsunami.
> The sequence of tokens that would destroy your production environment can be produced by your agent, no matter how much prompting you use.
If you have a specific sequence of an agent that blows up production during debugging, you can certainly check its probability and compare it to one (of same length) that does not blow up your environment. If the two differ by a meteroic amount, it could be pointing to errors in your inference pipeline.
Yet in this case, that probability clearly isn't smaller than a meteorite strike.