Crucible / reading the recordings
The front moves between frames.
A bright ring is a picture. Delivering a kick requires an arrival test. Step the same front through both methods and watch which stationary probes it reaches.
How this relates to the native sandbox
The selectable Sedov front uses a two-dimensional similarity radius, then a constant-speed continuation. At each physics substep its source, wind and particle passes inspect the interval from the old radius to the new radius. For this single stationary front, the crossing creates one impulse event; it is not a force applied again at every rendered frame.
R(t) = k √t, k ∝ E¼; then R advances at c₀ arrival: Rprevious < distance ≤ Rcurrent direct visibility: source → receiver avoids the wall
This is a dimensionless teaching model with fixed probes and exact intersections against two rectangles. Native visibility uses a finite set of SDF samples; thin geometry and moving particle walls have additional limitations. The switch illustrates direct occlusion, not diffraction, reflection, transmission or a compressible pressure solve. Neither the recordings nor this schematic validate physical blast pressures. The thin-ring method is an intentionally incomplete comparison, not a claim about the legacy solver.
Opening a sealed chamber and propagating a front are different questions. The chamber schematic explains connectivity and pressure release; this one explains arrival and obstruction after a front exists.