I don't know how much that has to do with China. I’d give them some credit, but I don’t think they single-handedly mended ties between SA and Iran.
Oman mediated a lot of talks between the two sides before China did. And the Saudi resistance to the JCPOA back then was that it would enable them to bankroll their proxies being that they would not be sanctioned or made a pariah. Today, there is no Assad, Hezbollah is severely weakened, and the Houthis are as well. Their (SA) fears are now centered around MBS grandiose visions being threatened by another regional conflict and so they’d prefer peaceful resolution this time around. It’s not because they’re friends, they just don’t want to be enemies.
If I’m a betting man, I’m not buying the Israeli’s threats. Israel won’t go at it alone as we heard previously, and Trump of all people showed reluctance to support them. The last thing the US needs is one more conflict to be involved in. The war in Ukraine and in Gaza exposed the US’ lack of necessary supply for a lot of weapons. Inching towards a nuclear weapon is the only good card Iran has left they’re not going to give it up easily.
However, I know I’d have to give the orange buffoon something even if I don’t buy Israel’s threats. Iran is probably going to go for a deal that appeases Trump but pisses off Israel. And Trump being Trump for all his bluster, will go easy on Iran. Iran knows the Apricot Ayatollah just wants a deal for the optics, more than he wants to make Israel happy. This is the same dude that was glazing the Houthis after signing that ceasefire with them and leaving Israel out of it. How many Republicans complained about that deal? Probably not a lot, and you definitely don’t hear about it all for it to be consequential.