Function dsf_observation_warrants_90pct_warning 

pub fn dsf_observation_warrants_90pct_warning(
    range_m: f64,
    mach_1_crossing_range_m: Option<f64>,
    solved_max_range_m: f64,
) -> bool

Whether the dsf verb’s “solution reliability degrades” warning should fire.

Two independent gates, BOTH required (MBA-1357 Task 2 review, Critical #1): a solve envelope sized to comfortably exceed a typical observation made the 90%-of-solved- range check alone fire unconditionally, since the envelope tracked the observation itself rather than the profile’s own real reach. Requiring the observation to also be beyond the trajectory’s Mach-1.0 crossing ties the warning to an actual downrange- position judgment (deep into the subsonic regime the DSF table’s low end targets), not merely wherever the caller happened to stop solving.