Captions

Figure Captions

Figure 1. Portal-hit density across the observer ladder.
Portal-hit density rises steadily across the near-side leg, drops sharply at the bridge checkpoint post_throat_backstep_01, and then re-densifies on the far side, reaching its maximum at exit_lookback.

Figure 2. Throat-event density across the observer ladder.
Throat-event density increases from mouth to throat, collapses at the bridge checkpoint, and then rises strongly again on the far side, peaking at exit_lookback after the post-throat re-densification.

Figure 3. Crossings per pixel across the observer ladder.
Crossings per pixel increase gradually along the near-side leg, collapse at the bridge checkpoint, and then re-densify sharply on the far side, peaking at post_throat_exit_approach before settling slightly at exit_lookback.

Figure 4. Segments per crossing across the observer ladder.
Transport cost per crossing decreases smoothly along the near-side leg, spikes dramatically at the bridge checkpoint, and then drops to its lowest values on the far side. This isolates the bridge as the dominant transport-cost anomaly in the validated ladder.

Figure 5. Mean optical path length across the observer ladder.
Mean optical path length decreases monotonically from mouth to throat, reaches its minimum at the bridge checkpoint, and then increases again on the far side. This shows that optical-path structure and interaction density decouple at the bridge transition.