fix(showcase): hay-bale quality pass with five new hygiene budgets, and exit-pre-sidecar doc accuracy

docs/gallery/gn-sdf-remesh/index.html

@@ -401,7 +401,7 @@ <h2>Source</h2>
     <span class="c"># EEVEE-id inversion witnessed for real: the OTHER era&#x27;s id must be</span>
     <span class="c"># rejected by this build, the helper&#x27;s accepted</span>
     eid = get_eevee_engine_id()
-    wrong = <span class="s">&#x27;BLENDER_EEVEE_NEXT&#x27;</span> <span class="k">if</span> bpy.app.version &gt;= (<span class="n">5</span>, <span class="n">0</span>, <span class="n">0</span>) <span class="k">else</span> <span class="s">&#x27;BLENDER_EEVEE&#x27;</span>
+    wrong = <span class="s">&#x27;BLENDER_EEVEE_NEXT&#x27;</span> <span class="k">if</span> bpy.app.version &gt;= (<span class="n">5</span>, <span class="n">0</span>, <span class="n">0</span>) <span class="k">else</span> <span class="s">&#x27;BLENDER_EEVEE&#x27;</span>  <span class="c"># engine-id-exempt: the wrong-era id this example asserts is rejected</span>
     <span class="k">try</span>:
         bpy.context.scene.render.engine = wrong
         print(<span class="s">f&quot;</span><span class="s">ERROR: wrong-era EEVEE id &#x27;</span>{wrong}<span class="s">&#x27; was accepted</span><span class="s">&quot;</span>, file=sys.stderr); <span class="k">return</span> <span class="n">5</span>

docs/gallery/index.html

@@ -1162,12 +1162,12 @@ <h2><a href="wooden-ladder/">wooden-ladder</a></h2>
       </article>
       <article class="card" data-tags="mesh export showcase">
         <a class="card-media" href="hay-bale/" aria-label="hay-bale showcase piece detail page">
-          <img src="assets/hay-bale-hero.webp" alt="hay-bale — A procedural bound hay bale with a cinched pillow loaf, end nap, and two sisal twine belts through UVs, bake, LOD, collider, and Unity glTF, asserting…" loading="lazy" decoding="async" />
+          <img src="assets/hay-bale-hero.webp" alt="hay-bale — A bound hay bale whose twine belts follow the loaf&#x27;s own raycast cross-section, asserting recomputed geometry budgets, not an API contract." loading="lazy" decoding="async" />
         </a>
         <div class="card-body">
           <h2><a href="hay-bale/">hay-bale</a></h2>
-          <p class="teaches">A procedural bound hay bale with a cinched pillow loaf, end nap, and two sisal twine belts through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.</p>
-          <p class="witnesses"><span class="tag">witnesses</span> Recomputed: 852 tris, two materials with 294 hay and 132 twine faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.920×0.517×0.426 m, zmin 0, hygiene 0, hay-twine BVH gap 0.07 mm, LOD ratios in band, convex collider 78 tris, non-empty glTF. --skip-decimate exits 9 on LOD1; --lift-z exits 16 on grounded zmin.</p>
+          <p class="teaches">A bound hay bale whose twine belts follow the loaf&#x27;s own raycast cross-section, asserting recomputed geometry budgets, not an API contract.</p>
+          <p class="witnesses"><span class="tag">witnesses</span> Recomputed: 2012 tris, two materials with 712 hay and 304 twine faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.921x0.530x0.409 m, zmin 0, hygiene and cross-shell z-fight 0, 5 shells, each belt wrapping under the loaf at zmin 2.6 mm, banded belt seat depth 4.0-16.8 mm over 20/20 stations on both belts, belt mirror error 0, cinch depth 14.2 mm, LOD ratios in band, convex collider 156 tris, non-empty glTF. --skip-decimate exits 9; --stray-vert 15; --lift-z and --float-belts 16; --slack-belt 18; --skew-belt 19.</p>
           <a class="card-link" href="hay-bale/">View showcase piece <span aria-hidden="true">&rarr;</span></a>
         </div>
       </article>

docs/gallery/iron-cauldron/index.html

@@ -413,7 +413,14 @@ <h2>Source</h2>
 
 
 <span class="k">def</span> eevee_engine_id():
-    <span class="k">return</span> <span class="s">&quot;BLENDER_EEVEE_NEXT&quot;</span> <span class="k">if</span> bpy.app.version &gt;= (<span class="n">4</span>, <span class="n">2</span>, <span class="n">0</span>) <span class="k">else</span> <span class="s">&quot;BLENDER_EEVEE&quot;</span>
+    <span class="s">&quot;&quot;&quot;EEVEE id: &#x27;BLENDER_EEVEE&#x27; on 5.0+, &#x27;BLENDER_EEVEE_NEXT&#x27; on 4.2-4.5.
+
+    Mapping matches examples/swatch-grid.get_eevee_engine_id, which asserts it
+    against the running build (copied, not imported). Inherited the inverted
+    form from showcase/shipping-crate; it returned &#x27;BLENDER_EEVEE_NEXT&#x27; on 5.x,
+    where that id does not exist.
+    &quot;&quot;&quot;</span>
+    <span class="k">return</span> <span class="s">&quot;BLENDER_EEVEE&quot;</span> <span class="k">if</span> bpy.app.version &gt;= (<span class="n">5</span>, <span class="n">0</span>, <span class="n">0</span>) <span class="k">else</span> <span class="s">&quot;BLENDER_EEVEE_NEXT&quot;</span>
 
 
 <span class="k">def</span> fail(msg, code):

docs/gallery/shipping-crate/index.html

@@ -399,7 +399,14 @@ <h2>Source</h2>
 
 
 <span class="k">def</span> eevee_engine_id():
-    <span class="k">return</span> <span class="s">&quot;BLENDER_EEVEE_NEXT&quot;</span> <span class="k">if</span> bpy.app.version &gt;= (<span class="n">4</span>, <span class="n">2</span>, <span class="n">0</span>) <span class="k">else</span> <span class="s">&quot;BLENDER_EEVEE&quot;</span>
+    <span class="s">&quot;&quot;&quot;EEVEE id: &#x27;BLENDER_EEVEE&#x27; on 5.0+, &#x27;BLENDER_EEVEE_NEXT&#x27; on 4.2-4.5.
+
+    Mapping matches examples/swatch-grid.get_eevee_engine_id, which asserts it
+    against the running build (copied, not imported). The old form here keyed
+    on &gt;= (4, 2, 0) and so returned &#x27;BLENDER_EEVEE_NEXT&#x27; on 5.x, where that id
+    does not exist — the render path raised TypeError on 5.1 and 5.2.
+    &quot;&quot;&quot;</span>
+    <span class="k">return</span> <span class="s">&quot;BLENDER_EEVEE&quot;</span> <span class="k">if</span> bpy.app.version &gt;= (<span class="n">5</span>, <span class="n">0</span>, <span class="n">0</span>) <span class="k">else</span> <span class="s">&quot;BLENDER_EEVEE_NEXT&quot;</span>
 
 
 <span class="k">def</span> fail(msg, code):

docs/gallery/swatch-grid/index.html

@@ -556,7 +556,7 @@ <h2>Source</h2>
     <span class="c"># Cycles. Witness the inversion for real: the OTHER era&#x27;s id must be rejected</span>
     <span class="c"># by this build, and the helper&#x27;s id must be accepted.</span>
     eid = get_eevee_engine_id()
-    wrong = <span class="s">&#x27;BLENDER_EEVEE_NEXT&#x27;</span> <span class="k">if</span> bpy.app.version &gt;= (<span class="n">5</span>, <span class="n">0</span>, <span class="n">0</span>) <span class="k">else</span> <span class="s">&#x27;BLENDER_EEVEE&#x27;</span>
+    wrong = <span class="s">&#x27;BLENDER_EEVEE_NEXT&#x27;</span> <span class="k">if</span> bpy.app.version &gt;= (<span class="n">5</span>, <span class="n">0</span>, <span class="n">0</span>) <span class="k">else</span> <span class="s">&#x27;BLENDER_EEVEE&#x27;</span>  <span class="c"># engine-id-exempt: the wrong-era id this example asserts is rejected</span>
     <span class="k">try</span>:
         sc.render.engine = wrong
         print(<span class="s">f&quot;</span><span class="s">ERROR: wrong-era EEVEE id &#x27;</span>{wrong}<span class="s">&#x27; was accepted by this build — </span><span class="s">&quot;</span>

docs/gallery/turntable/index.html

@@ -420,7 +420,7 @@ <h2>Source</h2>
     <span class="c"># the EEVEE-id mapping is asserted regardless of whether we render: the</span>
     <span class="c"># OTHER era&#x27;s id must be rejected by this build, the helper&#x27;s accepted</span>
     eid = get_eevee_engine_id()
-    wrong = <span class="s">&#x27;BLENDER_EEVEE_NEXT&#x27;</span> <span class="k">if</span> bpy.app.version &gt;= (<span class="n">5</span>, <span class="n">0</span>, <span class="n">0</span>) <span class="k">else</span> <span class="s">&#x27;BLENDER_EEVEE&#x27;</span>
+    wrong = <span class="s">&#x27;BLENDER_EEVEE_NEXT&#x27;</span> <span class="k">if</span> bpy.app.version &gt;= (<span class="n">5</span>, <span class="n">0</span>, <span class="n">0</span>) <span class="k">else</span> <span class="s">&#x27;BLENDER_EEVEE&#x27;</span>  <span class="c"># engine-id-exempt: the wrong-era id this example asserts is rejected</span>
     <span class="k">try</span>:
         bpy.context.scene.render.engine = wrong
         print(<span class="s">f&quot;</span><span class="s">ERROR: wrong-era EEVEE id &#x27;</span>{wrong}<span class="s">&#x27; was accepted</span><span class="s">&quot;</span>, file=sys.stderr); <span class="k">return</span> <span class="n">5</span>

examples/exit-pre-sidecar/README.md

@@ -5,17 +5,69 @@ Witnesses [`drivers-and-app-handlers`](../../skills/drivers-and-app-handlers/SKI
 `main` does not write the file. The host runner asserts it after the
 process exits (`tests/smoke/run_example.py --expect-sidecar`).
 
-5.1+. 4.5 LTS: `AttributeError` — no `exit_pre`. Skip
-(`SMOKE_SKIP: exit_pre requires Blender 5.1+`, exit 77, catalog
-`min_version` 5.1). `--force-run` bypasses the skip so 4.5 fails
-accessing the handler list.
+No gallery still. There is no geometry: the witness is a file that does
+not exist until the process is already gone, and a render would look
+identical whether the handler fired or not.
 
-No gallery still. There is no geometry.
+## The contract
 
-The harness checks **contents** (`sidecar_contains=exit_pre-ok`), not
-existence only. A file written from `main` or `atexit` is red. Several
-falsifiers exit 0 from the script so the **harness** can fail after Blender
-dies.
+`exit_pre` is the only handler in `bpy.app.handlers` that runs during
+interpreter teardown, and it is the difference between a callback that
+runs and one that silently never does. Code that relies on `atexit` for
+this — saving a session log, flushing a render manifest, releasing a
+licence token — is the class of bug this example exists to catch.
+
+| Blender | `hasattr(bpy.app.handlers, "exit_pre")` |
+| --- | --- |
+| 4.5.11 LTS | `False` — `AttributeError` on access |
+| 5.1.2 | `True` |
+| 5.2.1 LTS | `True` |
+
+Re-verified 2026-09-22 against all three binaries. `exit_pre` is also
+the only exit- or quit-related name in `bpy.app.handlers` on the
+versions that have it, so there is no older spelling to fall back to.
+
+API reference:
+[`bpy.app.handlers` (5.2 LTS)](https://docs.blender.org/api/current/bpy.app.handlers.html)
+·
+[`bpy.app.handlers` (4.5 LTS)](https://docs.blender.org/api/4.5/bpy.app.handlers.html)
+— the 4.5 page lists no `exit_pre`, which is the absence this example
+turns into a skip.
+
+## Why 4.5 skips rather than fails
+
+Exiting 77 on 4.5 is **correct by design**, not a gap in coverage. The
+handler does not exist there, so there is no contract to witness and no
+assertion that could meaningfully run. The catalog carries
+`min_version` 5.1 and the runner treats a skip above that floor as a
+FAIL, so the skip cannot quietly spread to a version that should run.
+`tests/smoke/summarize.py` makes a job red if *every* example skipped,
+so a repo-wide skip cannot pass either.
+
+`--force-run` bypasses the skip so 4.5 proves the absence rather than
+assuming it: the run exits 2 on `AttributeError`, and also exits 2 if
+`exit_pre` turns out to exist on a version that should not have it.
+
+## Falsifiers
+
+The harness checks the sidecar's **contents**
+(`sidecar_contains=exit_pre-ok`), not merely that a file appeared.
+Most falsifiers therefore exit **0 from the script** — Blender reports
+success — and the **harness** fails afterwards, which is the only place
+a post-exit contract can be falsified.
+
+| Flag | What it breaks | Script exit | Harness |
+| --- | --- | --- | --- |
+| `--no-handler` | nothing registered, nothing written | 0 | FAIL, no sidecar |
+| `--silent-handler` | `exit_pre` registered but writes nothing | 0 | FAIL, no sidecar |
+| `--wrong-text` | handler writes `nope` | 0 | FAIL, contents mismatch |
+| `--write-in-main` | `from-main` written in `main`, no handler | 0 | FAIL, contents mismatch |
+| `--atexit-instead` | `atexit` writes `atexit-ok` instead of `exit_pre` | 0 | FAIL, contents mismatch |
+| `--force-run` on 4.5 | asserts `exit_pre` is genuinely absent | 2 | n/a |
+
+`--write-in-main` and `--atexit-instead` are the two that matter: both
+produce a file, so an existence-only check would pass them. They are why
+the catalog row carries `sidecar_contains`.
 
 ## Run
 
@@ -28,6 +80,8 @@ python tests/smoke/run_example.py --name exit-pre-sidecar \
   --expect-sidecar /tmp/exit-pre.sidecar --sidecar-contains exit_pre-ok
 ```
 
+Append `-- --wrong-text` (or any flag above) to falsify.
+
 ## Exit codes
 
 Per-script sequential checks. `9` is a valid check code; there is no rule

examples/exit-pre-sidecar/exit_pre_sidecar.py

@@ -6,10 +6,15 @@
 handler writes it. The host runner (``tests/smoke/run_example.py``)
 asserts the file after the process exits.
 
-5.1+. 4.5 LTS has no ``exit_pre`` (AttributeError). Catalog
-``min_version`` 5.0 is wrong — the floor is 5.1. Skip: ``SMOKE_SKIP``.
+5.1+. 4.5 LTS has no ``exit_pre`` (AttributeError), so the catalog
+``min_version`` is 5.1 and the script skips below it (``SMOKE_SKIP``).
 ``--force-run`` bypasses the skip so 4.5 fails accessing ``exit_pre``.
 
+Re-verified 2026-09-22 on 4.5.11 LTS, 5.1.2 and 5.2.1 LTS:
+``hasattr(bpy.app.handlers, "exit_pre")`` is False / True / True, and
+``exit_pre`` is the only exit-related name in ``bpy.app.handlers`` on
+the versions that have it.
+
 No gallery still. There is no geometry.
 
     blender --background --python exit_pre_sidecar.py --

showcase/README.md

@@ -65,6 +65,13 @@ entry in `showcase/gallery.json`, and a rendered still.
   the last one over faces that share **no** vertex: the triangles of one
   flat fan cap are coplanar and close-centred by construction, and
   counting those makes the budget unsatisfiable rather than meaningful.
+  Count the coplanar pairs **cross-shell**, not merely over faces that
+  share no vertex: two quads two steps apart on one flat cap share no
+  vertex and are coplanar and close-centred by construction. Counting
+  those reported 96 pairs on `hay-bale`, none of them a hazard, which is
+  the same unsatisfiable-budget trap in a second disguise. Z-fighting is
+  two separate bodies landing on one plane, and that is a cross-shell
+  pair by definition.
   Multi-body props do **not** require Euler characteristic 2 — that is a
   single-shell contract. Two boxes that share a coplanar face z-fight;
   two that share a vertex weld into one shell. Seat a joint with a named
@@ -100,6 +107,26 @@ entry in `showcase/gallery.json`, and a rendered still.
   hypot-length box rotated about its centroid. The centroid form is
   short of one host and punches through the other. `--short-brace` /
   `--float-spout` (or the piece's equivalent) is the falsifier.
+- **Even shaping terms and mirror symmetry (exit 19).** Where a prop has
+  mirrored members — two belts, two brackets, a pair of feet — every
+  closed-form term in the host's shaping function must be **even** in
+  the mirrored axis. `hay-bale` used `sin(x*24)`, which is odd, so its
+  two belt stations sampled different surface heights and the wraps
+  shipped 5.4 mm out of step; `cos` fixed it exactly. Assert it: pair the
+  mirrored shells and compare their axis positions and extents within a
+  named epsilon. A bounding box cannot see this, and neither can a
+  per-member budget that only ever looks at one member.
+- **Wrappers follow the host's profile, and the host is finished first
+  (exit 16/18).** Build, bevel and **ground the host, then** hang the
+  wrapper on the finished surface by raycasting the host's own
+  cross-section at the wrapper's station. Placing a wrapper against
+  half-built geometry and shifting everything afterwards leaves each one
+  a different distance off the floor. A constant-section rectangle on a
+  rounded host stands proud at the middle of each face and is swallowed
+  at the corners — `hay-bale`'s belts stopped 2.9–8.3 mm above the floor
+  with a visible notch, while the AABB `zmin` gate stayed green because
+  the loaf grounded the box. Assert **per wrapper shell** that the loop
+  passes under the host, not just that something touches Z=0.
 - **Seat conformance (exit 18).** A band, hoop, strap or collar wrapped
   around a host asserts a **banded** seat depth — a minimum so it cannot
   float and a maximum so it cannot sink — sampled per angular segment
@@ -110,6 +137,14 @@ entry in `showcase/gallery.json`, and a rendered still.
   vertices as inner ones the moment the host is out of round, which is
   how a hoop that visibly gapped on one side still passed.   The paired
   falsifier makes the wrapper a true circle on an out-of-round host.
+  Measure the depth **station-locally**, along the vertex's own direction
+  from the station axis — not by nearest-surface distance. A wrapper
+  seated in a concave waist has its nearest host face on the bulge
+  shoulder at a neighbouring station, and the wrap then reads as sitting
+  10 mm outside a host it is in fact hugging. Bin the samples by
+  **rounding** to the nearest station, never by flooring: a station on a
+  bin boundary puts its inner and outer rings in different bins, and the
+  inner-only bin reports the wrapper's outer offset as its seat depth.
 - **Level sole on a raked leg (exit 18).** A raked stile does not sit
   in a world-axis cube. Build the sleeve in the member frame so it
   follows the rake; add the tread after the rake as its own