With the strong caveat that I haven't played BW only TB2 which isn't quite the same, I'm noting this rules text
You make tests during dramatic moments, when the outcome is uncertain.
When a player sets out a task for his character and states his intent, it is the GM’s job to inform him of the consequences of failure before the dice are rolled. “If you fail this…” should often be heard at the table. Let the players know the consequences of their actions.
Failure is not the end of the line, but it is complication that pushes the story in another direction. Once that is said, everyone knows what’s at stake and play can continue smoothly no matter what the result of the roll is.
We roll dice when a conflict arises.
When a test is failed, the GM introduces a complication.
"If nothing is at stake, say “yes” [to the player’s request], whatever they’redoing. Just go along with them. If they ask for information, give it tothem. If they have their characters go somewhere, they’re there. If theywant it, it’s theirs."*
Unless there is something at stake in the story you have created, don’t bother with the dice. Keep moving, keep describing, keep roleplaying. But as soon as a character wants something that he doesn’t have, needs to know something he doesn’t know, covets something that someone else has, roll the dice.
*The BW rules appear to incorporate this DotV rule.
<snip>
So far, one might
possibly interpret the rules text "When a player sets out a task for his character and states his intent" to mean what it says: GM indicates consequences up front (i.e. it's type B) only when players set out tasks for their characters. Whereas for other tests only "When a test is failed, the GM introduces a complication" applies (making it type A). Said other tests being triggered not by player intent, but by dramatic moments and conflict. Or one could understand the complication as simply being the concrete form given to the consequences indicated up front.
I think there is some relevant text missing from what you have quoted. The following extracts are from
BW Hub and Spokes (pp 9-11, 30-31), and set out the basic process of play:
In the game, players take on the roles of characters inspired by history and works of fantasy fiction. These characters are a list of abilities rated with numbers and a list of player-determined priorities. The synergy of inspiration, imagination, numbers and priorities is the most fundamental element of Burning Wheel. Expressing these numbers and priorities within situations presented by the game master (GM) is what the game is all about. . . .
The players interact with one another to come to decisions and have the characters undertake actions.
One of you takes on the role of the game master. The GM is responsible for challenging the players. He also plays the roles of all of those characters not taken on by other players; he guides the pacing of the events of the story; and he arbitrates rules calls and interpretations so that play progresses smoothly.
Everyone else plays a protagonist in the story. Even if the players decide to take on the roles of destitute wastrels, no matter how unsavory their exploits, they are the focus of the story. The GM presents the players with problems based on the players’ priorities. The players use their characters’ abilities to overcome these obstacles. To do this, dice are rolled and the results are interpreted using the rules presented in this book. . . .
[W]hat happens after the dice have come to rest and the successes are counted? If the successes equal or exceed the obstacle, the character has succeeded in his goal - he achieved his intent and completed the task.
This is important enough to say again: Characters who are successful complete actions in the manner described by the player. A successful roll is sacrosanct in Burning Wheel and neither GM nor other players can change the fact that the act was successful. The GM may only embellish or reinforce a successful ability test. . .
When the dice are rolled and don’t produce enough successes to meet the obstacle, the character fails. What does this mean? It means the stated intent does not come to pass.
The reason I've set this out is because they tell us
where the stakes come from,
what counts as a dramatic moment, and
what informs complications. These are all
relative to player-established priorities for their PCs - and are all referable back to the basic notion that
the GM presents the players with problems based on the players’ priorities.
Hence why BW is not "if you do it, you do it": the need to roll the dice is not triggered by
a player's action declaration falling under a certain action-type-description (like "trying to seize something by force" or "trying to read a situation*).
Nor is rolling dice triggered by "seeing consequences in the offing".
It is triggered by the interplay of
the way the GM's framing presents problems that pertain to player-authored priorities for their PCs and
the intention of the player's action declaration and how it relates to those priorities.
In Apocalypse World, there is scope for discussion, at the table, over whether or not a move has been triggered - the rulebook gives some examples. Those discussions are about whether or not a player's declared action really falls under the move-triggering description (eg "No, I'm not going aggro - if he really doesn't want to let me go past him, I'll go round the other way").
In Burning Wheel, there is also scope for discussion over whether or not the dice should be rolled, but that discussion is not about
whether the declared action falls under a certain description but rather what is at stake in the situation as framed and the player's intent in response to that. It's reasonable for - and the rulebook gently encourages - the GM to stamp out "test-mongering" where the dice are rolled with an eye purely to advancement but with nothing really as stake. And conversely, it's reasonable for the player to call for a test, or an extended conflict, if they think that something important to them and their PC is in play.
This is why BW is more likely to produce a "meta-" orientation in the participants than is AW (something that
@Campbell has often noted on these boards), although it is not the so-called "writers' room" of discussing plot or narrative trajectory, but rather a type of meta-level "introspection" of what really matters in the fiction.
Anyway, this is why I don't think that BW is either Type A or Type B as you've set them out, which is also why I agree with
@thefutilist that the Type A/Type B analysis is not convincing.
Your documented play from last year shows some of this stuff in action
he did the only thing he could think of - as someone whose Circles include the Path of Spite, and who has a reputation as ill-favoured for himself and others, he looked to see if a bloodletting or surgical necromancer or similar ill-omened type might be nearby the scene!
But the Circles check failed: and so no friendly bloodletter appeared, but rather the Death Artist Thoth, who - for reasons not yet clear, but certainly not wholesome - carries a lock of the hair of Aedhros's dead spouse
Was Thoth in sight before the roll or added as a complication after? If the latter, then this Circles test looks like type A. But then
Today's session began with the Surgery attempt to treat Alicia's mortal wound. It failed badly (we have the notes somewhere, but from memory the Ob was 14 (7 doubled for no tools) and 1 success was achieved), and so her Health check to avoid acquiring the Mortally Wounded in the Head trait will be against Ob 19. A roll of the dice determined that it will take her 8 months to regain full consciousness, at which point she will then have to recover from a Traumatic Wound.
Was "8 months to regain full consciousness" in sight before the roll? Possibly this example follows a common pattern for type B. Which is, rather than exhaustively and inefficiently listing all scalable and forking consequences to meet the standard of informing player of the consequences of failure before the roll, GM indicates only their form or direction (e.g. "this might make it worse")... which here was likely clearly enough known to all.
As you have quoted, the BW rules state that the consequences of failure must be announced prior to rolling.
However, as Luke Crane notes in the Adventure Burner (p 251, reproduced in the Codex, p 116-7):
I confess that I do not explicitly announce the terms of each test. Why? Two reasons: I find the result of failure implicit in most tests. If I'm doing my job correctly as the GM, the situation is so charged that the player knows he's going to get dragged into a world of **** if he fails. We project the consequences into the fiction as we're talking in pcharacter and jockeying before the test. . . .
The second reason . . . is a bad habbit ab BWHQ. My players trust me. They know I have a devious GM-brain that will take their interests into heart and screw them gently but firmly. I can't write rules about this kind of trust and, frankly, I think basing a game solely on trust is awful. . . . However, it does have a positive side. Withholding some failure results allows for the game to move a little faster. It varies the monotony of the testing structure and provides room for the occasional inspired surprise. . . .
Announcing the risks of failure before a roll is absolutely a good rule and practice to follow. It forms good habits. It adds a new dynamic to the game - knowing that failure isn't arbitrary when you roll the dice. I'm a poor role model, so definitely follow what's written in the book.
My own play drifts in the same direction as Luke's: the consequence of failure is very often implicit; and my players, who have known me for decades, trust me to be fair in my twists and surprises. Likewise when I'm playing I trust my GM.
In the example of play that you quote, the Circles test for Thoth is called for because it absolutely relates to Aedhros's Belief about Alicia, and also those other aspects of the character such as his Reputation. The failure is a standard invocation of the Enmity Clause for failed Circles tests.
The Surgery test for recovery is the standard one in the Anatomy of Injury sub-system. Like some of the other sub-systems, this one is closer to "if you do it, you do it" and less based around "intent and task" - though the players and GM could still dispense with it if they agreed nothing was at stake in the test. The roll for recovery time is also from the same rules sub-system.
Here's another example of a test from that same session, triggered I assume by player forcing matters along (intent)
Thoth, who has an Instinct to Always collect bits and pieces, also couldn't help but look around for Surgery tools, and succeeded on the Ob 10 test (Perception rolled for Beginner's Luck). A die of fate roll indicated that one corpse was available for collection, and Aedhros helped Thoth carry it off.
The Ob 10 test is Beginner's Luck Scavenging. The fact that Thoth has an Instinct shows that this is a player-authored priority, and hence is not an appropriate occasion simply to "say 'yes'".
The DoF to determine the number of corpses available would have been agreed between me and Thoth's player, in a context where the availability of corpses on the boat was agreed to be a "say 'yes'" matter.
That's followed by something that perhaps was entertained as a dramatic moment the situation was ripe for
At one point, something particularly grotesque happened (I think, as narrated by my friend, a bit of the body Aedhros was holding onto sloughed off) and a Steel test was called for and failed. Hesitating, Aedhros dropped the body, and it nearly landed in the water - but Thoth, driven by his desire for corpses!, succeeded on a Power test to not let go.
The Steel test here could count as an example of one of those "other tests" prompted by a dramatic moment: so type A (the body nearly fell in the water). In any case, I expect in play that the shift between types is fluid, and the rules wordings seem open to interpreting as
if we can see consequences, then we are going to roll dice, and then we are going to see consequences (type B/A)
The Steel subystem is another departure from strict intent+task resolution.
The GM is the one who calls for a Steel test (Revised pp 121-2):
A GM can call for a Steel test under three main conditions: When the character is confronted with surprise, fear or pain. . . . GMs call for Steel tests; players don't.
The rules specify the consequences for a failed Steel test - hesitation (= 10-Will actions), with the player having to choose their hesitation response.
The GM has to exercise judgement in determining whether to call for a Steel test as part of framing, or whether to use it as a consequence. I can't remember which it was in the example that you refer to - it's possible, for instance, that there was a failed Hauling test in there that I'd forgotten about when I wrote up the actual play. Or it may have been framing rather than consequence, in which case it really serves as a type of colour with a mechanical accompaniment.
The Power test for Thoth, on the other hand, is straight down the line, classic intent+task: I as GM am not going to "say 'yes'" given the stakes for Thoth the death-artist, and so a roll is called for and on a success Thoth gets his intent (ie keeping his corpse from falling into the harbour).