Totally agree. There needs to be some kind of short or long rest mechanism for healing.
I did not get the impression that short rest healing was on the table.
Maybe it's a tad conventional, but: a resource that's allocated dynamically to healing or other functions, giving the character the flexibility to support the party in a way that fits the current situation, and the player, incidentally, some 'agency.'
Kinda maybe sort-of, kinda not. Depends more on how your defining an at-will ability at that point.
OK, I'll take a stab: Something you can do every round it's applicable, regardless of how many times you've done it before, that is above and beyond the warm-body base line of actions anyone can take with no check or that can be resolved with just non-proficient checks & attacks.
Short rest is kind of the defacto assumption for martial style recharging powers. Of course Samaurai threw a monkey wrench in that and so there's a lot more options in designing this than trying to pigeon hole it into a short rest mechanic when it might fare better as something else.
Good enough for a fighter sub-class, perhaps, not so much a full class?
I don't think it matters as long as it feels right for the ability in question. Like a Battle Plan ability could easily be encounter based. It's something that can easily be envisioned as happening every encounter
That would make sense from the conceptual level. Then again, a given battle-plan might not work for every enemy & situation, and abstracting that would not be unreasonable.
Also, sticking to the plan could require focus - Mearls mentioned concentration, but didn't go there with the sub-class, but for a full class, could work. Heck, everyone wanting the benefits might have to concentrate on the plan. Plus, concentration is mechanically/conceptually analogous to Bo9S/4e stances.
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Making one set of abilities stronger means the other set of abilities needs to get weaker.
Not that I've observed. Or, rather, with a flexible resource, it's naturally taken care of by managing the resource. If you use all your CS dice for rally, your temp-granting ability was stronger, if you use some for precision strike your ability to hit was stronger and your granting temps weaker.
Enlarging the box of Daily abilities shrinks the box for at-will abilities and vice versa
OK, IDK if box size is the best metaphor.
5e isn't tightly or carefully balanced against extremes, as was pretty evident from the peek into the process that we got. But, it clearly does have a rough balance point at a certain day length. A certain number of rounds that your best (daily) or second-string(short rest) stuff applies, and the remainder phoned in with your at-wills. So, if you have kinda crap at-wills and no short rest abilities, a few dailies can be spectacular.
It seems fairly numerous and potent dailies are a given, driven by the option of adequate healing, which requires more modest at-wills.
So putting most of the class's more powerful functions in the same account as the healing seems the only plausible option.
And, since the class is not meant to quite match the cleric as iconic healer, that means the non-healing alternatives should be pretty nice... because that will result in less healing used, for one thing.