I'd appreciate some clarification on this ahead of teaching Netrunner to a friend next week:

If a Runner encounters, say, a Code Gate piece of ice at strength 3 and he has a strength 1 decoder icebreaker to use on it.

The Runner pumps the strength of his icebreaker up to 3 and then does whatever else he needs to to break the subroutines.

My question is: If the Runner continues the run and encounters a second strength 3 Code Gate and uses the same icebreaker to tackle it, does he have to strengthen the icebreaker all over again from the original strength of 1, or does the icebreaker retain the increased strength from the first encounter?

Thanks for your help.

Unless otherwise specified (the core set Shaper breakers do specify otherwise), strength boosts on icebreakers last only for a single piece of ice.

Yeah, I've noticed some cards that say the icebreaker has increased strength for the remainder of the run. But if it doesn't say that, it's a fresh encounter with the original strength.

That's great. Thanks for the help.

You're welcome.