In OC Siman 695 Sif 3 that if one starts their Purim seudah by day and finishes by night they should still say "Al Hanisim" in Bircas HaMazon. The Machaber brings an opinion that says to not say it; however, the Rema adds in that the minhag (custom) is like the first opinon to say it.
(This halacha is true even in Yerushalayim (and any other place) where Purim is celebrated on the 15th. I'm pointing this out so one shouldn't think that Purim is superior to Channukah with respect to this halacha in that in the evening from the 14th to the 15th one could argue that there is more of a reason to say al hanissim even after the day ended as long as the seudah started by day.)
My question is: is the same true by Channukah? If someone started a seudah on Zos Channukah (the last day of Channukah) and the seudah went into the night would the person also say al hanissim. The only difference I could think of is that by Purim there is an obligation to eat a meal. This is not the case by Channukah where the meal's not an obligation however under the right circumstances may be considered a mitzvah. Why this would be a difference for saying al hanissim or not after the day has ended I don't know: I'm just pointing out that this could be a possible difference that would affect the halacha. In any event, the Shulchan Aruch brings this point and makhlokes only by Purim and not by Channukah. So again, is it the same halacha by Channukah or perhaps over here there is no maklokes and everyone agrees that after the day has ended al hanissim shouldn't be said?
I've looked around and haven't seen anyone that discusses this yet so I'm bringing the question here.