I can't escape the impression that you aren't using the same definition I am for nociception. I otherwise agree with everything you've said as far as I can tell.
> And why ... if nociception is merely behavioral effects? ...
This is definitely not consistent with the definition I'm using. Rather, I'm using nociception to refer to the low level _physiological_ responses to damage (specifically the set of molecular pathways that are in some way organized as part of a larger systemic response to said damage).
The term pain can then be assigned to a particular qualia, leaving a few other phenomena on the levels in between the two. This makes nociception easy to speak and reason about and helps avoid some of the most confusing or apparently contradictory situations but otherwise leaves the higher level stuff (pain, motivation, various other qualia) as difficult to figure out as before.
In the case of complications related to anesthesia I'd say it's squarely in a grey area that the classification scheme I'm applying here doesn't handle as well. That's due partly to the line between physiology and psychology blurring at times, and partly to the (related) fuzziness of the term unconscious as it applies to an organism's biology.
Even when you're unconscious, a great deal of your nervous system still has to be functioning on some level in order to keep you alive. Since psychology arises from your nervous system, which is in turn made up of innumerable physiological effects, then it's not inconsistent with the definitions I'm using that we can observe nociceptive pathways resulting in changes to some of the higher level systems even if someone was unconscious while they were active.
> When Tanya decides to react to burning her hand on a stove by moving it away, is she really experiencing the exact same kind of nociception that you or I experience when we burn our hand on a stove and move it away?
I'd point out that (given the definition I've been using) we don't experience nociception but rather some higher level qualia that's downstream of it. Not knowing all that much about her case other than what appears in your article (ie pain insensitivity) I honestly have no idea. She obviously doesn't experience what any of us would describe as pain. Beyond that, how can we know what qualia someone else experiences? If we assume her to be otherwise identical to us then I suppose it would depend on exactly where in the pathway that runs from nociception to pain response her genetic abnormality manifested.
> ... despite the lack of qualia, look like learning processes about avoiding damage.
Precisely! As I'm modeling it, useful (evolutionarily) nociceptive pathways can give rise to avoidance or learning processes in any way whatsoever. All that's required is that their presence increase organism fitness!
In the case of many simpler organisms I suspect there might not be any qualia or learning whatsoever (and thus no loss function, bi-level or otherwise, on the level of an individual organism). Rather, nociceptive pathways might simply trigger some set of immediate, hard coded, higher level responses. (Consider C. elegans in particular and I think this will make a lot of sense.)
Up organism complexity a bit and you might encounter learning in the form of something resembling a simple state machine. In other words, employing nociceptive pathways to form a very basic set of associations between specific environmental conditions and some sort of danger or avoidance response. This could allow preemptively avoiding something that caused damage (and thus lowered fitness) in the past. (This might or might not be bi-level depending on what other learning pathways, if any, it interacted with.)
Under such a model, it's only when you make it up to incredibly complex organisms whose behavior is governed (to at least some extent) by higher level reasoning that you might encounter things we could identify as psychology, qualia, or pain. This is where bi-level losses seem to become particularly important and also where things rapidly become incredibly complicated to model.
That being said, it seems to me that a hardwired avoidance response (ie an outer loss) is likely only necessary for initial bootstrapping (in the case of sufficiently well educated humans) or in an organism where higher level reasoning is present (and thus driving behavior) but not sufficiently advanced. For example, it seems at least plausible that Tanya might have been fine if only there were some way to imbue her with a well developed understanding of the world. Then again, maybe not - it's quite possible that other internal processes have developed a dependence on the pain response being present, and so ripping it out without doing any other remodeling might well result in a "pain sized hole" and a nonviable organism.