diff --git a/docs/re/structures/regn-map-grid.md b/docs/re/structures/regn-map-grid.md
index 3dcd96c3..caad93f8 100644
--- a/docs/re/structures/regn-map-grid.md
+++ b/docs/re/structures/regn-map-grid.md
@@ -249,4 +249,47 @@ promoting it.
 ❔ So section 1 stays open. What would settle it is a test with power: pick a
 record, follow a candidate index, and check that the thing it lands on is
 spatially consistent with that record's own position and radius. That needs the
-tree walked, not the fields counted.
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+tree walked, not the fields counted.
+
+## ❌ The BVH reading is refuted — and slot 7 is a *local* scale
+
+**2026-08-26.** Last iteration I wrote that "position + positive scalar +
+integer links is the shape of a bounding-volume hierarchy node", explicitly as a
+reading of the shape. Tested with a design that has power, it fails.
+
+**The containment test.** If slots 8–11 hold child indices, a child's sphere
+should sit inside its parent's. Following every `u16` half of every integer slot
+and checking `|C_child − C_parent| + R_child ≤ R_parent` (2 % slack):
+
+    RANDOM control                   0 of 126 787  =  0.00 %
+    slot 8 half 0    63 389 tried    0.00 %
+    slot 8 half 1    63 395 tried    0.00 %
+    …every candidate…                0.00 %
+
+**The random control is the informative row.** It is also 0.00 %, which means no
+node's sphere contains any other node's sphere *anywhere in the file* — so there
+is no nesting for an index to point at, whatever the indices mean. The
+hypothesis fails before the indices are even in question.
+
+**Why**: slot 7 is far too small to bound neighbours.
+
+| | median | p10 | p90 |
+|---|---|---|---|
+| slot 7 | **3 139** | 1 965 | 9 275 |
+| pairwise centre distance | **45 457** | 19 071 | 126 295 |
+
+Slot 7 is **14× smaller** than the typical distance between nodes, and a random
+other centre falls within it only **0.40 %** of the time. It is also smaller
+than the smallest grid cell on any map (10 000).
+
+So ✅ **slot 7 is a local scale, not a hierarchy radius** — sub-cell sized, with a
+narrow spread. Together with 63 410 scattered centres across a 500 km cube, that
+is the shape of **many small independent volumes**, not a tree.
+
+🟡 That fits per-object collision volumes — a map's asteroids and debris, which
+the mission `Route` tables independently show as `Frame_S<NN>_Asteroid` records.
+Stated as a reading, not a measurement; nothing here counts objects.
+
+❔ Still open: what slots 8–11 index, and what the six pairs in 12–23 are. What
+this iteration removed is a wrong frame — the file is not a tree, so tree-shaped
+tests will keep returning nothing.
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