test: add optional public macro CV observations

docs/validation/refined_dfg_window.md

@@ -82,3 +82,16 @@ and the exact scenario. It does not relabel current source as historical evidenc
 Use the existing bounded plan/pilot/full commands with the three option flags above;
 full requires the matching completed t*=5 paired pilot. `step_seconds` includes force
 readback; observation/overhead and total wall time are separate, not kernel throughput.
+
+Add `--observe-cv` to record independent scalar control-volume samples from the
+already downloaded public macros. The pilot exercises this path at t*=.02..5;
+full records 501 endpoints at 290..300. Each `cv_history.jsonl` row contains actual
+root time, preceding interval start/duration/impulse, and two inventories/outward
+fluxes ordered [mass,Px,Py]. Exclude the first row's preceding impulse: that row
+supplies the initial inventory. Uniform native impulse converts by .5² to root
+units; refined ledger impulse is already in root units. Explicit native-aligned
+contours differ by .25 root cells in x and are recorded in the plan. Cropping
+retains the two-cell face-gradient stencils. No fields or per-link arrays are saved.
+`cv_observation_seconds` is the CV portion of observation/overhead time. Helper hash
+and the observation flag must match pilot/full. Time integration, temporal
+coarsening and any physical assessment remain separate offline work.