So, container effects are basically mobile, at least if they are not wards (and that is under review).
Suppose I set up a tent, and cast a type 2 Room Target spell on it, with Moon Duration. I then take the tent down, pack it up, and set it up again.
What happens to the spell?
What about if I use Room to ward a backpack against vermin? This is an ordinary floppy backpack, not a randoseru, so it is changing shape all the time.
What about if I cast it on a wooden hut, with a single room, and the hut flexes slightly in the wind?
If it isn't obvious, I am fishing for opinions on this because I suspect I need to say a bit about this in the clarification (particularly the tent thing), and I want to know where, in general terms, the line should be drawn. I suspect that everyone thinks the spell should persist in the last case, the hut, but what do you think about the others?
Honestly, I think a lot of questions about wards, rooms and containers are best answered contextually by the people in a saga on the basis of what helps their stories move along. If you want to make a story out of a limitation of hermetic magic, then rule against it; and, if having a mobile or flexible room that's magical is a stepping stone to a story everyone wants to get to, then rule for it.
I'm not sure if the specificity is going to help anyone who isn't someone on the forums who likes arguing about theoretical hermetic problems.
If I had to give an answer, I would just say that the "purpose" of a room or container target is that magic is using the boundaries you are giving to define what area it affects. Hermetic magic can have very flexible boundaries with the Ritual Boundary target. Unless the desire is for there be a hermetic flaw that makes room targets unusually rigid, I would say that it can just persist throughout the motion of an enclosed space so long as it isn't completely destroyed (much like a Boundary spell that targets a forest will not fail if parts of the forest are destroyed).
The interior of the tent isn't a Room while folded, so the spell collapses when its Target no longer exists. It's probably possible to design a tent that is raised, lowered, and folded in such a way that it has a defined, enclosed internal volume at every step in the process, and thus T:Room spells on it can persist (if you painstakingly fold it according to the instructions), but your basic canvas triangle folded flat or rolled up and tied to a bedroll would definitely not work this way. Enchanting it to shrink to a portable size without collapsing or being folded up flat might also work.
The backpack flexing doesn't make it stop qualifying for T:Room (it's still a chamber, still enclosed, and still has definite boundaries), so it's just fine.
Similarly, the wooden hut flexing in the wind doesn't make it stop qualifying for T:Room (it's still a chamber, still enclosed, and still has definite boundaries), so it's just fine.
I feel that it a tent is intended to be folded up, then that is just a natural state for a tent. I don't feel that should destroy a tent anymore than opening a chest or container can change the state of the container.
The hut I definitely feel would stay a room/structure for these spells.
The backpack, as long as it was always kept with a bit of space in it (either with something inside or holding it open when empty should be fine as well but should it be allowed to sit flat and empty I think it would no longer define a container and he spell should end but I would not argue this point strongly as the simpler thing in play is to just say that this isn’t allowed to happen with the “magical backpack the wonderful magi bestowed on the grog and told them how to care for it” or that it does not cancel the spell because it still defines a container.
The tent, OTOH, does not define a space when it doesn’t have the posts, rope, stakes, etc in its assembled state. Most “tents” of the period, outside of those of the nobles, I assume were not much more than tarps laid over a rope and/or poles. Maybe someone with more historical knowledge than me will say differently but that’s my assumption. Anyway, I’d assume a tent to cancel any container-style spells on it when it is dismantled.
The tent no longer defines a Room when disassembled, so the spell will fail then due to its Target no longer existing.
The backpack on the other hand retains its basic shape throughout, so there the spell will last.
(If the backpack had been cut into pieces, or turned inside out, then the Room container would no longer exist and the spell would fail.)
The hut obviously remains a Room throughout, so the spell will last there too.
I would tend to agree with @ErikT here. Noting only that I'm still not entirely sold on the idea of all containers being mobile. Maybe have them static, but can be mobile for an extra magnitude?
While I am not necessarily against the idea of the extra magnitude for mobile, such a change would require reviewing every "container spell/effect" in the entire line and adding errata for any that are possibly mobile.
While I do not believe there are an excessive amount of spells it would hit, there is a whole ton of enchanted effects it would.
I'm not certain the spell would fail if the tent is collapsed, but it would definitely be suppressed while it does not hold its normal configuration. How radically you'd have to change from the original configuration is a game master's call; for example, if the tent's roof collapsed I'd allow the spell to continue, but once it's folded down it's not really defining an empty space anymore.
Honestly Target: Container should be a standard Hermetic Target, using Room for backpacks or jars or purses is just a kludge.
part of the issue with the tent has to do with the tent design. A tent that is fundamentally of one piece (like a modern camp tent) defines a very small room when packed away. However a tent which does not include a floor, which would be true of most medieval tents, would stop being a room when it loses contact with the ground. Making a tent with a design specifically able to retain the spell would not be hard (aside from convincing the tent maker to do it), but it certainly would not be the norm.
I agree with this. I have not seen any medieval tent design where the floor was an integral part of the tent. And only the smaller tents have integral walls; any large tent has seperate walls, usually in several sections.
To me, the spells cast at the backpack and the hut remain in effect. I would also support adding a Target: Container option, with some sort of size limit (linked to the Form of the effect?) being +1 magnitude (instead of +2 for Room).
This, to me, is a common issue when playing with lots of ReVi spells for surpressing and sustaining, but my answer to the tent questions is
While the tent is up and forming a room, the spell is active and effective. While the tent is collapsed, the spell is active but NOT effective because there is not a valid target. Once the tent is made into a room again, it resumes being effective.
The spell isn't cancelled because there's not a valid target, its just awaiting becoming a valid target again to resume effectiveness.
I also second Arthur here (Flexible Rooms) that a Target: Container option is incredibly appealing for the backpack / chest / amphora / coffins of the world.
I share what appears to be the consensus: the spell stays on the hut, because it stays a hut; and the backpack, because it stays a backpack. As for the tent, I guess it ... depends on the tent!
Let me point out that this is not just about T:Room. It's about T:Ind as well, and it deals with more than folding; it deals with identity. If I cast a T:Ind spell on a ship, and disassemble it into its individual parts, does the spell remain attached to the individual parts? What if I replace some parts of the ship? What if I replace all? What if I keep the parts, but one part at a time I completely change the configuration of the ship by changing how they are assembled? Ultimately, every spell on a target that transforms over time, however slightly, has to adjudicate what happens if that target transforms.
To make the answer clearer and more general (in my opinion!) a Container (as a technical term identifying Targets such as Circle, Room, Structure, Boundary etc. - see the errata discussion) is something having:
a) a clear, concrete boundary (which represents, but is not the Container).
b) an inside.
c) an identity, that allows (an omniscient being) to keep saying it's that container over time.
A "type 2" spell cast on the container lasts only as:
d) the container remains a container, and in fact that container on which the spell was cast.
a,b,c, and d always require adjudication, though it's usually easy.
In the given example, they hold for the backpack (unless perhaps it's turned inside out?) and the hut.
They may hold for the folded tent, if it's still a tent and still has an "inside" -- this is probably untrue if it was disassembled instead of being folded (this includes a tent whose floor was the ground - you may fold it, but if you carry it around, you are ... probably? doing so after having disassembled the floor).
I can see the temptation, but I'm not a huge fan. It affects a potentially huge number of discreet objects.
I'm fine with calling this sort of thing a small Room.
That said, one could argue that Room is simply a special case of this container - namely Container w/ Size +1.