re: containment screen fails too -- the static assembler inflates a shared turret

envelope_screen measures per-axis protrusion past the sibling envelope, the
relationship the eye used. It still does not flag e106_bdy_03, and dumping the
static assembly shows why: e303_wep_01's world box is 1600x2100x4800 around a
~400x400x2000 hull, so nothing can protrude. The decode is innocent -- that
resource is 49x23x42 in every container -- so the static assembler is inflating
it 30-110x per axis, non-uniformly. The screen is only meaningful once placement
is trustworthy, and the assembler now has a worse defect than the decoder had.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

crates/sylpheed-formats/examples/envelope_screen.rs

@@ -0,0 +1,106 @@
+//! Does every part of a ship sit inside the envelope its siblings describe?
+//!
+//! `slab_screen` compared *scale* and could not see the `e106` slab. What the eye
+//! used when the render exposed it was **relationship**: a blocky mass sitting
+//! apart from the hull. This measures that — assemble a ship, and for each part
+//! ask how far its world box protrudes beyond the box of all the OTHER parts,
+//! relative to the ship's own size. A mis-anchored block sticks out; a real part,
+//! however big, is part of the silhouette.
+//!
+//! Usage: envelope_screen <resource3d_dir> [protrusion_fraction]
+use sylpheed_formats::mesh::Xbg7Model;
+use sylpheed_formats::ship::{assemble_ship, ship_id_of};
+use std::collections::{BTreeSet, HashSet};
+
+fn main() {
+    let dir = std::env::args().nth(1).expect("resource3d dir");
+    let limit: f32 = std::env::args().nth(2).and_then(|s| s.parse().ok()).unwrap_or(0.35);
+    let mut files: Vec<_> = std::fs::read_dir(&dir)
+        .unwrap()
+        .flatten()
+        .map(|e| e.path())
+        .filter(|p| p.extension().and_then(|s| s.to_str()) == Some("xpr"))
+        .collect();
+    files.sort();
+
+    let mut flagged = 0usize;
+    for f in &files {
+        let Ok(bytes) = std::fs::read(f) else { continue };
+        let ids: BTreeSet<String> = Xbg7Model::anchor_models_cancellable(&bytes, 0.0, &|| false)
+            .iter()
+            .filter_map(|m| ship_id_of(&m.name).map(|s| s.to_string()))
+            .collect();
+        for id in &ids {
+            let placed = assemble_ship(&bytes, id, true);
+            if placed.len() < 3 {
+                continue;
+            }
+            let want: HashSet<String> = placed.iter().map(|p| p.resource.clone()).collect();
+            let models = Xbg7Model::models_named(&bytes, &want, &|| false);
+            // World box per placement.
+            let mut boxes: Vec<(String, [f32; 3], [f32; 3])> = Vec::new();
+            for p in &placed {
+                let Some(m) = models.iter().find(|m| m.name == p.resource) else { continue };
+                let (mut lo, mut hi) = ([f32::MAX; 3], [f32::MIN; 3]);
+                for s in &m.meshes {
+                    for q in &s.positions {
+                        let w = p.apply(*q);
+                        for k in 0..3 {
+                            lo[k] = lo[k].min(w[k]);
+                            hi[k] = hi[k].max(w[k]);
+                        }
+                    }
+                }
+                if lo[0] != f32::MAX {
+                    boxes.push((p.resource.clone(), lo, hi));
+                }
+            }
+            if boxes.len() < 3 {
+                continue;
+            }
+            for i in 0..boxes.len() {
+                // Envelope of every OTHER part.
+                let (mut lo, mut hi) = ([f32::MAX; 3], [f32::MIN; 3]);
+                for (j, b) in boxes.iter().enumerate() {
+                    if i == j {
+                        continue;
+                    }
+                    for k in 0..3 {
+                        lo[k] = lo[k].min(b.1[k]);
+                        hi[k] = hi[k].max(b.2[k]);
+                    }
+                }
+                // Per-AXIS: a bow legitimately extends the ship along its long
+                // axis, so protrusion only means something measured against the
+                // envelope's size IN THAT AXIS. The e106 slab stuck ~1 500 out in
+                // Y where its siblings spanned ~800.
+                let mut worst = 0.0f32;
+                let mut worst_out = 0.0f32;
+                for k in 0..3 {
+                    let size_k = hi[k] - lo[k];
+                    if size_k <= 1.0 {
+                        continue;
+                    }
+                    let out_k = (lo[k] - boxes[i].1[k]).max(boxes[i].2[k] - hi[k]).max(0.0);
+                    if out_k / size_k > worst {
+                        worst = out_k / size_k;
+                        worst_out = out_k;
+                    }
+                }
+                let (out, size) = (worst_out, 1.0f32);
+                let _ = size;
+                if worst > limit {
+                    flagged += 1;
+                    println!(
+                        "{:<20} {:<22} protrudes {:>7.0} beyond its siblings ({:.0}% of the ship)",
+                        f.file_name().unwrap().to_string_lossy(),
+                        boxes[i].0,
+                        out,
+                        100.0 * worst
+                    );
+                }
+            }
+        }
+    }
+    println!("{flagged} parts protrude more than {:.0}% of their ship's size", 100.0 * limit);
+}

docs/re/structures/xbg7-mesh.md

@@ -1097,6 +1097,34 @@ that carry it) and `t901_e01_D` is 58×59×3013 (a mast). And `f101_bdy_01` flag
 at 6× while being **capture-verified exact** in the truth table — a useful
 reminder that a bulky hull is not a bug.
 
+### The containment screen fails too — because the static placement is worse
+
+`examples/envelope_screen.rs` is the metric the eye actually used: assemble a
+ship, and for each part measure how far its world box protrudes past the box of
+all the *other* parts, **per axis** (a bow legitimately extends the long axis, so
+protrusion only means something against that axis' own envelope).
+
+It does not flag `e106_bdy_03` either, before or after the coverage fix. Dumping
+the static assembly shows why, and the reason is a bigger finding than the screen:
+
+```
+e106_bdy_03   X[ -300,  300]  Y[    0, 1600]  Z[  188, 1186]
+e303_wep_01   X[-1179,  421]  Y[ -996, 1104]  Z[-2368, 2432]   ← shared turret
+e106_bdy_04   X[ -215,  215]  Y[ -165,  234]  Z[ -991,  389]
+```
+
+The **turret swallows the ship**: `e303_wep_01`'s world box is 1600×2100×4800
+around a hull of ~400×400×2000, so nothing can protrude past the envelope. Its
+*decode* is not at fault — the resource comes out 49×23×42 in `Stage_S01` through
+`Stage_S06` alike, consistent everywhere — so this is a **static-assembler**
+defect: the placement blows a 49-unit turret up by 30–110× per axis (and
+non-uniformly, so it is not a simple scale factor).
+
+Two conclusions. The screen is only meaningful once placement is trustworthy, and
+**the static assembler has a worse defect than the decoder did** — one that the
+capture-baked path for `e106` hides, because the baked table places the ship
+correctly and is what the viewer prefers.
+
 ### The anchor work has plateaued at 98.7 % — state and what is left
 
 Four evidence-driven changes took the decoder from 5 480 to **6 212 of 6 294**