Verdict
The IP-101 furniture-scatterer path is now wired end-to-end and the synthetic layout-drift prior was measured. A two-edit glue (a furniture field on SceneOverrides, injected into the staged scene.json by scene_stage) connects the existing csi_drift schedule + the runner's _write_box_ply support, which were present but never called from the launch path. Ten exp-csi-static runs (two five-state arms) gate-passed with furniture rendered as box scatterers; the csi_layout_drift.py reduction produced drift_curve.parquet + a T*(epsilon) cadence for each arm.
What we tested
A deterministic five-state displacement schedule (0.25 m steps, seed-fixed directions, 16 placements at fixed occupancy on test-lab-synth-floor-0 / the three-link corridor layout), run twice: an off-path arm (four furniture items in the room corners) and an in-path arm (three reflective metal boxes across the Tx--Rx corridor link). Furniture was injected per state via config_overrides_path YAML (the MCP params path stringifies nested lists, so the YAML overlay is the correct route).
What we found
- Off-path: occupancy error is pinned at the calibration residual (
mean_amp_db: 0.308 persons) and does not move across the full 1 m of rearrangement (Spearman flat; max delta < 0.001). - In-path: error grows with displacement --- 0.290 -> 0.358 -> 0.511 -> 0.661 persons through 0.75 m --- as the blockage the model was fit to moves out from under it (
mean_amp_dbswings -76 -> -180 dB); it dips to 0.496 at 1.0 m as one box clears the LOS (non-monotonic tail). - Cadence: at a one-person budget both arms tolerate the full sweep (
T*(eps=1)=1.0 m); ateps=0.5the in-path arm crosses near 0.5 m while the off-path arm never does.
Interpretation
Drift is not a property of rearrangement in general but of rearrangement in the sensing geometry: a count model can be calibrated once and ignore furniture outside the link path, but must re-anchor against furniture near the links. T*(epsilon) is set jointly by the error budget and by how much rearrangement happens near the links --- exactly the design input a real recalibration schedule needs.
Honest scope
In-silico, design input only (IP-101 Q3=A) --- recalibration-trigger-from-drift stays plausible. The in-path boxes are deliberately reflective metal (an upper bound on furniture effect, not a typical room); the Rician-K feature degenerates to -inf under the near-total blockage they produce, so the curve is read on the attenuation feature alone. The operational cadence remains a multi-day hardware measurement this curve is built to design, not replace.