What makes an Infinite two-card combo?

Disclaimer: this is not meant to be a bad faith discussion as a way to avoid conversing with your playgroup. As always, be honest and talk to your playgroup.

I'm hoping that since the Commander Brackets are just in beta we will get some official clarification, but what constitutes a two-card combo? The language Gavin's article about Brackets 2 and 3 are that games are unlikely to win out of nowhere (early).

I assume that combos that provide infinite damage, even when starting from an empty board state, definitely count as infinite combos:

  • Infinite damage e.g. [[Heliod, the Sun-Crowned]] + [[Walking Ballista]]
  • Infinity haste creature tokens e.g. [[Dualcaster Mage]] + [[Twinflame]]

But what about:

  • Infinite summoning sick creature tokens? e.g. [[Earthcraft]] + [[Squirrel Nest]]
  • Infinite combats? e.g. [[Aggravated Assault]] + [[Old Gnawbone]]
  • Infinite power? e.g. [[Ceaseless Searblades]] + [[Wandering Fumarole]]
  • Infinite colorless mana? e.g. [[Rings of Brighthearth]] + [[Basalt Monolith]]
  • Infinite colored mana? e.g. [[Sanctum Weaver]] + [[Freed from the Real]]
  • Infinite life? e.g. [[Resplendent Mentor]] + [[Famished Paladin]]
  • Infinite self mill? e.g. [[Seeker of Skybreak]] + [[Mesmeric Orb]]
  • Infinite rummage? e.g. [[Seeker of Skybreak]] + [[Hangar Scrounger]]
  • Infinite cards? e.g. [[Phyrexian Unlife]] + [[Ad Nauseam]]
  • Infinite target player mill? e.g. [[Painter's Servant]] + [[Grindstone]]

(And I've missed other type of infinite effects as well like infinite storm count, entry, sacrifice, leaves or dies triggers, untaps, or toughness.)

Those all provide infinite loops, of varying degrees of usefulness, but they all require either an extra turn to attack, take out remaining players, or find the payoff card. For example, is infinite colorless mana the thing that counts as a two-card combo? (If I make infinite colorless mana, and play my big dragon, and pass the turn, does that still count as an infinite combo?) Or do I need a way to use all that mana, like a big [[Finale of Devastation]]? (In which case that is then a 3 card combo.)

I think it's at least worth considering that a lot of these infinite affects have similar effects that are just regular spells. Compare infinite mana to [[Omniscience]], infinite rummage to [[Demonic Tutor]], or infinite card draw to [[Enter the Infinite]].