Also [2] https://en.wikipedia.org/wiki/Misty_(satellite)

No, it is not. I'm not offering theory, I'm offering physics.

>none of which change the reality that no nation has EVER attempted to add low-observability features to it's military satellites

That you've never heard reports of projects like "Misty" (by the US NRO) is nice, but doesn't inspire much confidence in your statements either.

>Mostly because none of the ideas you sketched would actually work, in practice, to effectively hide a functional satellite.

Of course they would. This isn't, well, rocket science. We know how to make radar stealth shapes. Same math would work in space, in fact even more easily since there is no need to worry about aerodynamics nor necessarily stealth except in one direction. Lowering optical observability isn't even just a military thing, SpaceX themselves are literally doing it with Starlink, the subject of this subthread! They've been doing that to reduce albedo so as to cause less disruption for Earth-based astronomy. As I said, I certainly don't know if any major efforts have been made at serious thermal stealth, but not because it's some complex idea but merely due to tradeoffs in mass. Starship will allow launching 100-150 tons to LEO though with much larger fairings (last reported diameter I saw was 9m). As with all sorts of other things that will offer, the military will certainly be able to contemplate spending mass and volume on things that wouldn't have been worth the tradeoff before.

>The US, Russia, and China are all perfectly capable of tracking manuverable spacecraft and satellites, and we all do so 24/7/365.

Sure, the same way they can track maneuverable aircraft... so long as they aren't stealthed.

>Ever since the deployment of nuclear-capable ICBMs (~1961),space has been THE primary delivery avenue for the single biggest existential threat (thermonuclear war) to the most paranoid and technologically advanced nations on earth. Space is where you get nuked from!

You've gone entirely off topic and also seem pretty confused here. It's right there in the name: ICBM, the "B" is "ballistic", not "orbital". Orbital nukes are in fact specifically banned by treaty as too disruptive. ICBMs and SLBMs follow a ballistic trajectory. They're not space-based. There has been significant support for not making orbit a battlefield, due to rightful concerns about things like Kessler syndrome. Part of MAD and monitoring that has indeed been rocket launch monitoring satellites as well as ground based stations, but none of that has anything to do with spy sats. Monitoring sats have zero need to be stealthy, just to cover the whole planet at once. If either ICBMs are detected being launched or suddenly all your monitoring satellites get taken out, well conclusions can be drawn. In fact part of the core part of MAD is specifically to forego things which could be destabilizing by increasing odds a first strike could work.

>If effective low-observability spacecraft were a real thing, don't you think that at some point in the last 60 years, one of these nations would have deployed such a weapon... or addressed the concept in an arms control treaty... Or even discussed it publicly?

Um, nope? Not at all? As I said, while there have been experiments I don't think they are that much of a thing yet because there wasn't much need nor the mass budget for it. Up until modern times not that many countries/organizations could in fact track all the spy sats, and anyway the far more important interest was simply having lots and lots of them. Why put budget into fewer stealthy ones vs more and more better ones? But as the barriers to observation and tracking have fallen, and as mass/vol budgets go up, the time may indeed come when stealth will get renewed focus beyond existing experiments.

Again, when theorizing about future things that haven't necessarily been done yet, necessarily it's important to consider the physics of it. The physics here though are pretty straight forward frankly.

>If you find some credible examples of anybody discussing low-observability ICBMs

I remain completely mystified how you jumped from "a satellite in space" to "ICBM" if you have the slightest clue about what any of this stuff is. ICBMs aren't satellites, cannot be stealthed, and have zero need to be stealthed either. The only thing they need is decoys and that indeed has been done and is part of the reason (along with destabilization) serious strategic missile defense (against a peer opponent, not merely a rogue state handful) is considered infeasible. Stealth satellites would be about intelligence or perhaps fallback CnC or comms.