diff --git a/docs/re/BACKLOG.md b/docs/re/BACKLOG.md
index b81f0bf..f50fdcd 100644
--- a/docs/re/BACKLOG.md
+++ b/docs/re/BACKLOG.md
@@ -150,3 +150,61 @@ comparison is no longer merely the next step — it is the only remaining one.**
 Render `e106` in the viewer beside `ship_render`'s output of the same
 `assemble_ship` result; if they agree, the bug is in neither and the original
 report needs re-grounding against a specific ship and a specific expectation.
+
+---
+
+## ⚠️ The format layer is NOT exonerated — `assemble_ship` draws a non-renderable volume
+
+**Found 2026-08-11 by finally doing the visual**, which the notes above kept
+naming as the next step. It overturns their conclusion.
+
+Render `e106` from the static assembly and from the baked runtime capture and
+compare — `ship_render` does both:
+
+| | placements | parts |
+|---|---|---|
+| runtime capture (ground truth) | **8** | `bdy_01…04`, `brg_01`, `eng_01`, `eng_02`, `wep_02_01` |
+| `assemble_ship(--static)` | **11** | the same 8, **plus `e303_wep_01` ×2** and a second `e106_eng_01` |
+
+The render makes it obvious: the destroyer sits inside a white slab that dwarfs
+it ([capture](captures/e106-static-assembly-volume-bug.png)). That slab is
+`e303_wep_01`, and its own geometry is:
+
+```
+e303_wep_01     172 verts, 110 tris   bounds X[-1000, 600] Y[-1050, 1050] Z[-2400, 2400]   1600 x 2100 x 4800
+e106_wep_02_01 1002 verts, 772 tris   269 x 179 x 417      ← what a real e106 turret looks like
+e106_brg_01     202 verts, 202 tris   105 x  76 x 305
+```
+
+**110 triangles, perfectly round axis-aligned bounds, and bigger than the ship it
+is mounted on.** That is not a turret. 🟡 It reads as a collision / trigger
+volume, and ✅ whatever it is, **the game does not draw it**: the runtime capture
+of e106 contains no `e303_wep_01` at all.
+
+### Why this was missed
+
+`assemble_ship` treats **every** `rou_*` node in the composite as a drawable
+part, and the doc comment states the cross-id mount as intended behaviour —
+`"INCLUDING repeated instances and cross-id turret mounts (rou_e303_wep_01_root
+×2 on the e106 hull)"` — with
+`ship::tests::static_assembly_matches_runtime_capture` asserting
+`count("e303_wep_01") == 2`. The absence from the capture was explained away as
+vbase dedup, but **dedup would show one instance, not zero**.
+
+The test cannot catch it either: it walks the capture's parts and looks each up
+in the static output, so **extra** static placements are invisible to it. That is
+the same shape of gap as the earlier `include_external` hypothesis — a test that
+can only fail one way.
+
+### Scope, stated carefully
+
+Sweeping all 335 assembled ships for the signature *ship-scale span with under
+400 triangles* flags **20 ships and 58 placements** over 28 distinct resources
+(`e005_ant_*`, `f001_ant_*`, `f002_bdy_*`, `f301_barrel`, `f303_body`,
+`e303_wep_01`, …). **Only the `e106`/`e303_wep_01` case is proven** — by render,
+by capture absence, and by geometry. Some of the others may be legitimately large
+low-poly parts, and each needs the same three checks before being called a bug.
+
+**Next:** decide the rule that separates drawable parts from volumes (candidates:
+the node-name suffix, a descriptor flag, or the triangle-density heuristic), then
+re-point `static_assembly_matches_runtime_capture` so it also fails on extras.
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