Hmm, Sifr would've been more clear if it had used something similar Eater's wording e.g. the strength of that ICE cannot be more than 0 for the remainder of the encounter.
Yes, that's mechanically different from how it appears to work but to me the given explanation of how it works is, well, fiddly and messy as it seems like the ICE strength can vary in meaningful ways mid-run e.g.:
Ninja vs Negotiator + Sandburg - Runner has 1 credit, Corp has 14. Runner uses Sifr and is intending to just break the "Trash 1 program" subroutine allowing the +2 creds, but the the +2 creds triggers first and so bumps it up a notch meaning it's now STR 1 and so the runner can't break the second subroutine.
Have I understood that right as far as we know? (Edit: nope, see next post)
It seems like a fair few complications are avoided by no rezzing being allowed after encounter starts and Runner going first so paid abilities probably not getting fired by corp (e.g. there's no point rezzing Corporate Troubleshooter, but saving the ability for the next phase). However, An Offer You Can't Refuse flips this on its head and cards like IT Department come into play - now you can't just look at the board state and the cards played, the sequence in which they were played becomes very significant, which to me is clunky for this particular kind of interaction (again, if I had indeed understood it right)