fix(examples): redesign mesh-hygiene-audit as a flanged street valve with marked defects

README.md

@@ -992,19 +992,21 @@ with the Smooth-by-Angle modifier on 5.1.
 </tr>
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 <td width="46%" valign="middle">
-<a href="examples/mesh-hygiene-audit/"><img src="examples/mesh-hygiene-audit/preview.webp" alt="Mesh hygiene audit: dual-panel dirty vs clean brass street valves filling the frame — left with backlit through-hole, emissive boundary tubes and loose-vert bead over a DIRTY placard, right intact CLEAN manifold — proving the engine-ingest topology checklist" /></a>
+<a href="examples/mesh-hygiene-audit/"><img src="examples/mesh-hygiene-audit/preview.webp" alt="Mesh hygiene audit: two blue flanged street valves with brass handwheels — the left dirty copy with a red-outlined hole, a red flipped patch on the bonnet, an amber ngon on the base flange and three red loose-vert beads, the right one intact — proving the engine-ingest topology checklist" /></a>
 </td>
 <td valign="middle">
 
 ### [mesh-hygiene-audit](examples/mesh-hygiene-audit/)
 
 The mesh-cleanliness contract a prop pipeline relies on before engine ingest:
 no ngons, no loose vertices, every edge bordering exactly two faces, no
-zero-area faces, positive signed volume, and Euler `V − E + F == 2` for a
-closed solid (measured 66/136/72, volume 0.652001). Companion to
+zero-area faces, contiguous and outward winding on all eight parts of a
+flanged street valve, and Euler `V − E + F == 2` on its body casting
+(measured 802/1632/832, volume 0.453344). Companion to
 [`collision-hull-proxy`](examples/collision-hull-proxy/) (hull watertightness)
-and [`bmesh-gear`](examples/bmesh-gear/) (parametric closed solids). Dual-panel
-still: DIRTY through-hole + loose-vert bead vs CLEAN manifold (same brass).
+and [`bmesh-gear`](examples/bmesh-gear/) (parametric closed solids). Still: a
+dirty copy with a hole, flipped patch, ngon and loose verts marked from live
+audit data beside the intact valve; the paint glows red on any back face.
 
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docs/gallery/index.html

@@ -739,12 +739,12 @@ <h2><a href="gp-lineart-contour/">gp-lineart-contour</a></h2>
       </article>
       <article class="card" data-tags="bmesh mesh game-pipeline">
         <a class="card-media" href="mesh-hygiene-audit/" tabindex="-1" aria-hidden="true">
-          <img src="assets/mesh-hygiene-audit-hero.webp" alt="Two brass spool-shaped props labelled DIRTY and CLEAN; the dirty one has glowing orange stray edges inside it." loading="lazy" decoding="async" />
+          <img src="assets/mesh-hygiene-audit-hero.webp" alt="Two blue street valves with brass handwheels: the left has a red-outlined hole, a red bonnet patch, an amber flange patch and three red beads beside it; the right is intact." loading="lazy" decoding="async" />
         </a>
         <div class="card-body">
           <h2><a href="mesh-hygiene-audit/">mesh-hygiene-audit</a></h2>
-          <p class="teaches">Engine-ingest mesh hygiene on an octagonal street valve: no ngons, no loose verts, manifold edges, no zero-area faces, positive signed volume, Euler V-E+F==2. Dual-panel still shows a through-hole and loose-vert bead derived from live mesh incidence — same brass on both so color alone cannot carry the proof.</p>
-          <p class="witnesses"><span class="tag">witnesses</span> Pipelines that skip topology gates ship open boundaries, loose verts, or non-sphere Euler into engine ingest. The still makes the boundary hole and loose vert readable; ngon / zero-area / full winding invert remain check-only.</p>
+          <p class="teaches">Engine-ingest mesh hygiene on every part of a flanged street valve: no ngons, no loose verts, manifold edges, no zero-area faces, contiguous and outward winding, Euler V-E+F==2 on the body casting. A dirty copy carries a hole, a flipped patch, an ngon and loose verts, each marked from live audit incidence; the paint glows red wherever the renderer sees a back face.</p>
+          <p class="witnesses"><span class="tag">witnesses</span> Pipelines that skip topology gates ship open boundaries, flipped patches, ngons, loose verts or stray shells into engine ingest. The still shows the first four on a dirty copy; zero-area faces and a buried second shell remain check-only.</p>
           <a class="card-link" href="mesh-hygiene-audit/">View example<span class="sr-only"> mesh-hygiene-audit</span> <span aria-hidden="true">&rarr;</span></a>
         </div>
       </article>

examples/gallery.json

@@ -487,9 +487,9 @@
     {
       "name": "mesh-hygiene-audit",
       "dir": "examples/mesh-hygiene-audit",
-      "teaches": "Engine-ingest mesh hygiene on an octagonal street valve: no ngons, no loose verts, manifold edges, no zero-area faces, positive signed volume, Euler V-E+F==2. Dual-panel still shows a through-hole and loose-vert bead derived from live mesh incidence — same brass on both so color alone cannot carry the proof.",
-      "alt": "Two brass spool-shaped props labelled DIRTY and CLEAN; the dirty one has glowing orange stray edges inside it.",
-      "witnessesFix": "Pipelines that skip topology gates ship open boundaries, loose verts, or non-sphere Euler into engine ingest. The still makes the boundary hole and loose vert readable; ngon / zero-area / full winding invert remain check-only.",
+      "teaches": "Engine-ingest mesh hygiene on every part of a flanged street valve: no ngons, no loose verts, manifold edges, no zero-area faces, contiguous and outward winding, Euler V-E+F==2 on the body casting. A dirty copy carries a hole, a flipped patch, an ngon and loose verts, each marked from live audit incidence; the paint glows red wherever the renderer sees a back face.",
+      "alt": "Two blue street valves with brass handwheels: the left has a red-outlined hole, a red bonnet patch, an amber flange patch and three red beads beside it; the right is intact.",
+      "witnessesFix": "Pipelines that skip topology gates ship open boundaries, flipped patches, ngons, loose verts or stray shells into engine ingest. The still shows the first four on a dirty copy; zero-area faces and a buried second shell remain check-only.",
       "hero": "docs/gallery/assets/mesh-hygiene-audit-hero.webp",
       "preview": "examples/mesh-hygiene-audit/preview.webp",
       "tags": [

examples/mesh-hygiene-audit/README.md

@@ -1,8 +1,10 @@
 # Mesh Hygiene Audit
 
-A runnable example that builds an octagonal street valve body and runs the
-**engine-ingest mesh hygiene checklist** as executable topology checks,
-following [`mesh-editing-and-bmesh`](../../skills/mesh-editing-and-bmesh/SKILL.md).
+A runnable example that builds an upright flanged street valve — body
+casting, side outlet, 22 flange bolts, gland nut, threaded stem, brass
+handwheel hub, rim and spokes — and runs the **engine-ingest mesh hygiene
+checklist** on every part as executable topology checks, following
+[`mesh-editing-and-bmesh`](../../skills/mesh-editing-and-bmesh/SKILL.md).
 
 **Pipeline arc neighbors:** watertight / Euler on collision *hulls* in
 [`collision-hull-proxy`](../collision-hull-proxy/), parametric closed solids
@@ -12,67 +14,87 @@ in [`bmesh-gear`](../bmesh-gear/), LOD face budgets in
 pipeline runs on the *render* mesh before hull / LOD / export.
 
 **Scope:** this witnesses the bpy-level contract a prop pipeline relies on
-(tris+quads, no loose verts, manifold edges, no zero-area faces, outward
-winding, Euler 2 for a closed solid). It is not an engine exporter.
+(tris+quads, no loose verts, manifold edges, no zero-area faces, consistent
+and outward winding, Euler 2 for the genus-0 body casting). It is not an
+engine exporter.
 
 **What it witnesses:** every gate is derived from mesh combinatorics or the
-divergence-theorem volume — never from a prior-run capture:
+divergence-theorem volume — never from a prior-run capture. Gates 3–7 run on
+all eight parts; the Euler gate runs on the body casting, the one closed
+genus-0 shell the other parts mount on (the handwheel rim is a torus, the
+bolt and spoke meshes are many shells, so a single-sphere Euler test does
+not describe them):
 
 - **No ngons.** `len(poly.vertices) <= 4` for every face.
 - **No loose vertices.** Every vert has degree ≥ 1.
 - **Manifold edges.** Every edge borders exactly 2 faces (closed solid).
 - **No zero-area faces.** Face area > 1e-10; prints measured `min_area`.
+- **Consistent winding.** Every manifold edge is `BMEdge.is_contiguous` —
+  a flipped patch leaves seam edges whose two faces traverse it the same way.
 - **Outward winding.** Positive signed volume (divergence theorem).
-- **Euler sphere.** `V − E + F == 2` for the clean closed manifold
-  (measured: verts=66 edges=136 faces=72, volume≈0.652001, min_area≈1.146e-02).
+- **Euler sphere.** `V − E + F == 2` on the body casting
+  (measured: verts=802 edges=1632 faces=832, volume≈0.453344,
+  min_area≈1.223e-03).
 
-**What each check catches on failure:** loose vert injected (exit 4);
-face deleted → boundary edges (exit 5); edge dissolved → ngon (exit 3);
-all faces flipped → signed volume negated (exit 7); face collapsed →
-zero-area (exit 6).
+**What each check catches on failure** (`--inject KIND`, default target the
+body casting, `--inject-part NAME` for any other part): `ngon` → exit 3;
+`loose` → exit 4; `boundary` (one face deleted) → exit 5; `zero_area` (face
+collapsed) → exit 6; `flip_patch` (one face flipped) → exit 7 on winding
+seams; `flip` (all faces) → exit 7 on negative volume; `shell` (a leftover
+second closed shell buried inside) → exit 8, the one defect every per-edge
+gate misses. `--inject-ngon` is kept as an alias for `--inject ngon`.
 
-**Version witness:** output is byte-identical on Blender 4.5.11 LTS and
-5.1.2 — same counts, same volume, same `min_area`.
+**Version witness:** the check output is identical on Blender 5.2.1 LTS,
+5.1.2 and 4.5.11 LTS — same counts, same volume, same `min_area`.
 
-**Render as proof:** dual panel, same brass on both. DIRTY stages a
-camera-facing through-hole (boundary edges) plus a loose vert; emissive
-beads/edge tubes are built from the live mesh incidence the check uses —
-not decorative paint. CLEAN is the intact manifold. An out-of-frame AREA
-light rakes through the hole from behind so the aperture reads warm without
-a visible light panel in frame.
+**Render as proof:** a dirty copy of the same valve (left) beside the clean
+valve (right), same paint on both. The dirty body casting carries four real
+gate failures, each placed on the camera-facing side: a hole through the
+globe (open boundary), a flipped patch on the bonnet dome, an ngon merged
+into the base-flange annulus, and three stray loose vertices. The markers are
+read back from the dirty mesh's audit incidence, not from the staging code:
+boundary edges become glowing red tubes, loose verts red beads, ngon faces an
+amber material slot. The flipped patch and the inside of the hole need no
+marker — the paint mixes to red on the shader's own `Backfacing` output, so
+the renderer shows every face it sees from behind. On the clean valve that
+same material shows no red anywhere, because no back side is visible on a
+closed, outward-wound shell. The render path refuses to write a still
+(exit 9) if staging loses any of the four defect classes.
 
-**Not depicted in the still (check-proven only):** ngon dissolve, zero-area
-collapse, and full-mesh winding invert — they do not read as geometry at
-thumbnail scale without faking annotation.
+**Not depicted in the still (check-proven only):** zero-area collapse and
+the buried second shell — neither changes a single pixel.
 
 ## Run
 
 ```bash
 blender --background --python mesh_hygiene_audit.py --
-blender --background --python mesh_hygiene_audit.py -- --inject-ngon
+blender --background --python mesh_hygiene_audit.py -- --inject ngon
+blender --background --python mesh_hygiene_audit.py -- --inject flip_patch --inject-part Valve.HandwheelRim
 blender --background --python mesh_hygiene_audit.py -- --output hygiene.png
 blender --background --python mesh_hygiene_audit.py -- --output hygiene.png --engine cycles
 ```
 
 ## Exit codes
 
 Per-script sequential checks. `9` is a valid check code; there is no rule
-against it. `10` is the shared framing helper.
+against it. `10` is the shared framing helper, `11` the shared asset-quality
+helper.
 
 | Code | Meaning |
 | --- | --- |
 | 0 | Success |
 | 1 | Uncaught exception (FATAL wrapper) |
 | 2 | argparse / usage |
-| 3 | Ngon present (`--inject-ngon` lands here) |
+| 3 | Ngon present (`--inject ngon` lands here) |
 | 4 | Loose vertices |
 | 5 | Non-manifold or boundary edges |
 | 6 | Zero-area faces |
-| 7 | Signed volume ≤ 0 |
-| 8 | Euler characteristic ≠ 2 |
-| 9 | `--output` produced no file |
+| 7 | Winding seam edges, or signed volume ≤ 0 |
+| 8 | Body casting Euler characteristic ≠ 2 |
+| 9 | `--output` produced no file, or dirty staging lost a defect class |
 | 10 | Gallery framing violation |
+| 11 | Gallery asset-quality floor violation |
 
 The `blender-smoke` workflow runs the check on Blender 5.2 LTS and 4.5 LTS
 (5.1 on the weekly cron, the `needs-5.1` PR label, or manual dispatch).
-Smoke does not pass `--output` or `--inject-ngon`.
+Smoke does not pass `--output` or `--inject`.