Function quotes_in_reverse 

fn quotes_in_reverse(
    params: &[f64],
    rungs: &[Rung],
    budget: usize,
    quotes_for: &'_ mut dyn FnMut(&[AReal<f64>]) -> Result<Vec<AReal<f64>>, CalibrationError>,
) -> Result<(Vec<f64>, Vec<Vec<f64>>, JacobianEngine), CalibrationError>

The reverse engine: every rung’s quote recorded once on the thread’s calibration tape, the parameters registered as inputs and the quotes as outputs, and dq read back by vector sweeps over that one recording — width directions per sweep, as many sweeps as budget makes necessary. Returns (read_back, dq, Reverse { sweeps }).

Called only by route’s reverse arm, which has already established that no recording is open on this thread.