Constant REENTRY_BACKOFF 

pub const REENTRY_BACKOFF: f64 = _; // 0.125f64

Back-off fraction applied to s when a waypoint’s inner solve struggles: s ← min(1, s + REENTRY_BACKOFF). Re-entering a heavier regime and re-descending with a halved step is the floor behavior — there is no rejection alternative.

Exactly one waypoint of the lockstep grid (1/CONTINUATION_WAYPOINTS): a bounce off the homotopy floor re-enters the previous waypoint’s heavier regime, the lightest regime already proven solvable on this walk. Combined with the halved re-descent step, a one-notch bounce costs ~2 walk legs (the re-entry plus one finer re-descent). The previous two-notch back-off (0.25) cost ~4 legs per bounce, which starved the bounded walk budget under repeated mass-floor bounces and left the K≥2 joint fit stranded mid-path — handed to the solver half-annealed, the routing-collapse signature.