diff --git a/examples/armature-bend/README.md b/examples/armature-bend/README.md
index 5c1ab38..0bb6ce9 100644
--- a/examples/armature-bend/README.md
+++ b/examples/armature-bend/README.md
@@ -35,11 +35,33 @@ joints are the same weights the LBS check asserts.
 # Cheap correctness check (no render) — the CI check:
 blender --background --python armature_bend.py --
 
+# Falsifier: rest pose. Must exit non-zero (tip deflection).
+blender --background --python armature_bend.py -- --zero-curl
+
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
 blender --background --python armature_bend.py -- --output bend.png
 blender --background --python armature_bend.py -- --output bend.png --engine cycles
 ```
 
-It exits non-zero on failure (edit-bone lifetime violation, LBS deviation, moved root
-ring, or an undeformed tip). The `blender-smoke` workflow runs the check on Blender
-5.2 LTS and 4.5 LTS.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | `edit_bones` populated in object mode |
+| 4 | Edit-mode bone chain off closed form |
+| 5 | Evaluated vertex count changed |
+| 6 | Evaluated mesh off closed-form LBS |
+| 7 | Root ring moved |
+| 8 | Tip did not deflect (`--zero-curl` lands here) |
+| 9 | `--output` produced no file |
+
+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 `--zero-curl`.
+
diff --git a/examples/armature-bend/armature_bend.py b/examples/armature-bend/armature_bend.py
index 9f3be71..12a9c69 100644
--- a/examples/armature-bend/armature_bend.py
+++ b/examples/armature-bend/armature_bend.py
@@ -19,10 +19,14 @@
 The same API works unchanged on Blender 4.5 LTS and 5.1 — no version gate is
 needed, which this example demonstrates by running identically on both.
 
+``--zero-curl`` leaves every pose bone at rest and still asserts the tip
+deflects. That is the falsifier (``--same-axis`` in export-preset-axis).
+
 By default it runs only the correctness check (no render) — the CI smoke
 check. Pass --output to also render a still:
 
     blender --background --python armature_bend.py --                 # check only
+    blender --background --python armature_bend.py -- --zero-curl      # must fail
     blender --background --python armature_bend.py -- --output b.png  # + render
 """
 import bpy, bmesh, sys, os, math, argparse
@@ -294,10 +298,13 @@ def main():
     p.add_argument("--output", default=None, help="optional: render a still PNG here")
     p.add_argument("--engine", default="eevee", choices=("eevee", "cycles"),
                    help="render engine for --output (cycles for GPU-less hosts)")
+    p.add_argument("--zero-curl", action="store_true",
+                   help="leave pose bones at rest (must fail)")
     args = p.parse_args(argv)
 
     bpy.ops.wm.read_factory_settings(use_empty=True)
-    tube, arm = build_rig(CURL_DEG)
+    curl = 0.0 if args.zero_curl else CURL_DEG
+    tube, arm = build_rig(curl)
     code = check(tube, arm)
     if code:
         return code
diff --git a/examples/attribute-domain-shear/README.md b/examples/attribute-domain-shear/README.md
index 89b3fff..53637f1 100644
--- a/examples/attribute-domain-shear/README.md
+++ b/examples/attribute-domain-shear/README.md
@@ -50,11 +50,30 @@ per `docs/VISUAL-STYLE.md`.
 
 ```bash
 blender --background --python attribute_domain_shear.py --
+blender --background --python attribute_domain_shear.py -- --no-overwrite
 blender --background --python attribute_domain_shear.py -- --output shear.png
 blender --background --python attribute_domain_shear.py -- --output shear.png --engine cycles
 ```
 
-Exits non-zero on failure. The `blender-smoke` workflow runs the check on
-Blender 5.2 LTS and 4.5 LTS. The `--output` render path additionally measures
-framing against the Layer 1 band via `examples/gallery_framing.py` (exit 10
-on violation) before writing the still.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it. `10` is the shared framing helper.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | CORNER or POINT attribute size wrong |
+| 4 | CORNER hub corners off wedge color |
+| 5 | POINT hub is not last-write (`--no-overwrite` lands here) |
+| 6 | Outer ring verts off last-write order |
+| 7 | Measured shear off palette closed form, or ~0 |
+| 9 | `--output` produced no file |
+| 10 | Gallery framing 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 `--no-overwrite`.
+
diff --git a/examples/attribute-domain-shear/attribute_domain_shear.py b/examples/attribute-domain-shear/attribute_domain_shear.py
index f49db2c..3cbcb10 100644
--- a/examples/attribute-domain-shear/attribute_domain_shear.py
+++ b/examples/attribute-domain-shear/attribute_domain_shear.py
@@ -26,6 +26,7 @@
 check. Pass --output to also render a still:
 
     blender --background --python attribute_domain_shear.py --                 # check only
+    blender --background --python attribute_domain_shear.py -- --no-overwrite  # must fail
     blender --background --python attribute_domain_shear.py -- --output a.png  # + render
 """
 import bpy, bmesh, sys, os, math, argparse, colorsys
@@ -98,13 +99,14 @@ def assign_corner(me, pal):
     return attr
 
 
-def assign_point_naive(me, pal):
+def assign_point_naive(me, pal, overwrite=True):
     """The AI mistake: author per-wedge colors into a POINT-domain attribute.
     Every wedge rewrites the shared hub (and its leading ring vert), so the
     last wedge wins — colors shear across every shared vertex."""
     attr = me.color_attributes.new(ATTR_P, type='FLOAT_COLOR', domain='POINT')
     hub_index = 0  # build_fan creates the hub first
-    for i in range(K):
+    last = K if overwrite else 1
+    for i in range(last):
         # naive per-wedge pass: set the hub and both ring verts to palette[i]
         attr.data[hub_index].color = pal[i]
         attr.data[1 + i].color = pal[i]
@@ -113,7 +115,7 @@ def assign_point_naive(me, pal):
     return attr
 
 
-def check():
+def check(overwrite=True):
     pal = palette()
     expect_shear = closed_form_shear(pal)
     print(f"palette K={K} closed_form_shear={expect_shear:.6f}")
@@ -138,7 +140,7 @@ def check():
 
     # --- POINT: the shear, measured against the closed form ---
     me_p = build_fan()
-    attr_p = assign_point_naive(me_p, pal)
+    attr_p = assign_point_naive(me_p, pal, overwrite=overwrite)
     if len(attr_p.data) != len(me_p.vertices) or len(me_p.vertices) != K + 1:
         print(f"ERROR: POINT attr size {len(attr_p.data)} != verts {len(me_p.vertices)}",
               file=sys.stderr)
@@ -383,11 +385,13 @@ def main():
     p.add_argument("--output", default=None, help="optional: render a still PNG here")
     p.add_argument("--engine", default="eevee", choices=("eevee", "cycles"),
                    help="render engine for --output (cycles for GPU-less hosts)")
+    p.add_argument("--no-overwrite", action="store_true",
+                   help="write only the first POINT wedge (must fail)")
     args = p.parse_args(argv)
 
     print(f"binary version: {bpy.app.version} ({bpy.app.version_string})")
     bpy.ops.wm.read_factory_settings(use_empty=True)
-    code = check()
+    code = check(overwrite=not args.no_overwrite)
     if code:
         return code
 
diff --git a/examples/color-attribute-wheel/README.md b/examples/color-attribute-wheel/README.md
index 3d8e4a8..b516145 100644
--- a/examples/color-attribute-wheel/README.md
+++ b/examples/color-attribute-wheel/README.md
@@ -25,11 +25,33 @@ Color, not just present in the node tree.
 # Cheap correctness check (no render) — the CI check:
 blender --background --python color_attribute_wheel.py --
 
+# Falsifier: POINT-domain attribute. Must exit non-zero.
+blender --background --python color_attribute_wheel.py -- --point-domain
+
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
 blender --background --python color_attribute_wheel.py -- --output wheel.png
 blender --background --python color_attribute_wheel.py -- --output wheel.png --engine cycles
 ```
 
-It exits non-zero on failure (missing/mis-sized/mis-domained attribute, wrong
-active attribute, a probe color mismatch, or an unlinked Attribute node). The
-`blender-smoke` workflow runs the check on Blender 5.2 LTS and 4.5 LTS.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | Topology ≠ closed form |
+| 4 | Color attribute missing |
+| 5 | Domain/type ≠ CORNER/FLOAT_COLOR (`--point-domain` lands here) |
+| 6 | Attribute sized to verts, not loops |
+| 7 | `active_color` not set |
+| 8 | Probe loop color off HSV closed form |
+| 9 | `--output` produced no file |
+
+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 `--point-domain`.
+
diff --git a/examples/color-attribute-wheel/color_attribute_wheel.py b/examples/color-attribute-wheel/color_attribute_wheel.py
index accd594..86e01aa 100644
--- a/examples/color-attribute-wheel/color_attribute_wheel.py
+++ b/examples/color-attribute-wheel/color_attribute_wheel.py
@@ -18,6 +18,7 @@
 check. Pass --output to also render a still:
 
     blender --background --python color_attribute_wheel.py --                 # check only
+    blender --background --python color_attribute_wheel.py -- --point-domain   # must fail
     blender --background --python color_attribute_wheel.py -- --output w.png  # + render
 """
 import bpy, bmesh, sys, os, math, colorsys, argparse
@@ -56,7 +57,7 @@ def wheel_geometry():
     return coords, hsv
 
 
-def build_wheel():
+def build_wheel(point_domain=False):
     bpy.ops.wm.read_factory_settings(use_empty=True)
     coords, hsv = wheel_geometry()
     me = bpy.data.meshes.new("ColorWheel")
@@ -80,16 +81,18 @@ def build_wheel():
     # created via color_attributes (not the deprecated vertex_colors alias),
     # sized to loops -- then filled by expanding per-vertex HSV across corners
     # with bulk foreach_get / foreach_set, never a per-loop Python assignment.
-    attr = me.color_attributes.new(ATTR_NAME, type='FLOAT_COLOR', domain='CORNER')
-    n_loops = len(me.loops)
-    loop_vert = array('i', [0]) * n_loops
-    me.loops.foreach_get("vertex_index", loop_vert)
-    flat = array('f', [0.0]) * (n_loops * 4)
-    for i, vi in enumerate(loop_vert):
-        h, s, v = hsv[vi]
-        r, g, b = colorsys.hsv_to_rgb(h, s, v)
-        flat[i * 4], flat[i * 4 + 1], flat[i * 4 + 2], flat[i * 4 + 3] = r, g, b, 1.0
-    attr.data.foreach_set("color", flat)
+    domain = 'POINT' if point_domain else 'CORNER'
+    attr = me.color_attributes.new(ATTR_NAME, type='FLOAT_COLOR', domain=domain)
+    if not point_domain:
+        n_loops = len(me.loops)
+        loop_vert = array('i', [0]) * n_loops
+        me.loops.foreach_get("vertex_index", loop_vert)
+        flat = array('f', [0.0]) * (n_loops * 4)
+        for i, vi in enumerate(loop_vert):
+            h, s, v = hsv[vi]
+            r, g, b = colorsys.hsv_to_rgb(h, s, v)
+            flat[i * 4], flat[i * 4 + 1], flat[i * 4 + 2], flat[i * 4 + 3] = r, g, b, 1.0
+        attr.data.foreach_set("color", flat)
     me.color_attributes.active_color = attr  # the step AI code most often forgets
 
     obj = bpy.data.objects.new("ColorWheel", me)
@@ -283,9 +286,11 @@ def main():
     p.add_argument("--output", default=None, help="optional: render a still PNG here")
     p.add_argument("--engine", default="eevee", choices=("eevee", "cycles"),
                    help="render engine for --output (cycles for GPU-less hosts)")
+    p.add_argument("--point-domain", action="store_true",
+                   help="create a POINT-domain color attribute (must fail)")
     args = p.parse_args(argv)
 
-    obj, hsv = build_wheel()
+    obj, hsv = build_wheel(point_domain=args.point_domain)
     code = check(obj, hsv)
     if code:
         return code
diff --git a/examples/damped-track-aim/README.md b/examples/damped-track-aim/README.md
index 7f70621..5529afb 100644
--- a/examples/damped-track-aim/README.md
+++ b/examples/damped-track-aim/README.md
@@ -26,11 +26,34 @@ wired to `examples/gallery_framing.py`, call it with
 # Cheap correctness check (no render) — the CI check:
 blender --background --python damped_track_aim.py --
 
+# Falsifier: mute every constraint. Must exit non-zero.
+blender --background --python damped_track_aim.py -- --mute
+
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
 blender --background --python damped_track_aim.py -- --output aim.png
 blender --background --python damped_track_aim.py -- --output aim.png --engine cycles
 ```
 
-It exits non-zero on failure (wrong constraint type/target/axis, or evaluated
-aim outside the angular epsilon). The `blender-smoke` workflow runs the check
-on Blender 5.2 LTS and 4.5 LTS.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | Needle count ≠ 12 |
+| 4 | Needle does not carry exactly one DAMPED_TRACK |
+| 5 | Constraint target is not Core |
+| 6 | `track_axis` is not TRACK_Z |
+| 7 | Constraint muted or influence < 1 (`--mute` lands here) |
+| 8 | TRACK_TO still present |
+| 9 | Evaluated aim dot below 0.998 |
+| 10 | `--output` produced no file |
+
+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 `--mute`.
+
diff --git a/examples/damped-track-aim/damped_track_aim.py b/examples/damped-track-aim/damped_track_aim.py
index d3c19f1..49c917a 100644
--- a/examples/damped-track-aim/damped_track_aim.py
+++ b/examples/damped-track-aim/damped_track_aim.py
@@ -12,10 +12,14 @@
 constraint is missing, muted, mistyped as TRACK_TO, or the axis is flipped,
 the dot product fails.
 
+``--mute`` mutes every DAMPED_TRACK and still asserts unmute. That is the
+falsifier (``--same-axis`` in export-preset-axis).
+
 By default it runs only the correctness check (no render) — the CI smoke
 check. Pass --output to also render a still:
 
     blender --background --python damped_track_aim.py --                 # check only
+    blender --background --python damped_track_aim.py -- --mute           # must fail
     blender --background --python damped_track_aim.py -- --output aim.png
 """
 import bpy, bmesh, sys, os, math, argparse
@@ -161,7 +165,7 @@ def make_dielectric(name, color, roughness=0.35):
     return mat
 
 
-def build():
+def build(mute=False):
     bpy.ops.wm.read_factory_settings(use_empty=True)
     col = bpy.context.collection
 
@@ -186,6 +190,8 @@ def build():
         con.name = "AimCore"
         con.target = core
         con.track_axis = "TRACK_Z"
+        if mute:
+            con.mute = True
         needles.append(ob)
 
     bpy.context.view_layer.update()
@@ -376,9 +382,11 @@ def main():
         choices=("eevee", "cycles"),
         help="render engine when --output is set",
     )
+    p.add_argument("--mute", action="store_true",
+                   help="mute every DAMPED_TRACK (must fail)")
     args = p.parse_args(argv)
 
-    core, needles = build()
+    core, needles = build(mute=args.mute)
     code = check(core, needles)
     if code != 0:
         return code
diff --git a/examples/depsgraph-export/README.md b/examples/depsgraph-export/README.md
index 4355819..6ddfaca 100644
--- a/examples/depsgraph-export/README.md
+++ b/examples/depsgraph-export/README.md
@@ -17,6 +17,9 @@ export) rather than the unmodified base mesh.
 # Cheap correctness check (writes an OBJ to a temp path, asserts the counts) — the CI check:
 blender --background --python depsgraph_export.py --
 
+# Falsifier: apply_modifiers=False. Must exit non-zero (export ≠ evaluated).
+blender --background --python depsgraph_export.py -- --unevaluated
+
 # Also render a still of base vs evaluated (EEVEE on a GPU host; cycles on GPU-less hosts):
 blender --background --python depsgraph_export.py -- --output depsgraph.png
 blender --background --python depsgraph_export.py -- --output depsgraph.png --engine cycles
@@ -25,8 +28,27 @@ blender --background --python depsgraph_export.py -- --output depsgraph.png --en
 blender --background --python depsgraph_export.py -- --obj exported.obj
 ```
 
-It exits non-zero on failure (modifier not applied, or exported count ≠ evaluated count). The
-`blender-smoke` workflow runs this check on Blender 5.2 LTS and 4.5 LTS: base 8 → evaluated/exported
-98 vertices with a 2-level SUBSURF.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it. `10` is the shared framing helper.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | Evaluated mesh did not apply the modifier |
+| 4 | No OBJ written |
+| 5 | Export vert count ≠ evaluated (`--unevaluated` lands here) |
+| 6 | `--output` produced no file |
+| 10 | Gallery framing violation |
+
+`--obj` is a path selector, not a falsifier.
+
+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`, `--obj`, or `--unevaluated`.
+
 
 The `--output` render path additionally measures framing against the Layer 1 band via `examples/gallery_framing.py` (exit 10 on violation) before writing the still.
diff --git a/examples/depsgraph-export/depsgraph_export.py b/examples/depsgraph-export/depsgraph_export.py
index 14d7062..b3cd1eb 100644
--- a/examples/depsgraph-export/depsgraph_export.py
+++ b/examples/depsgraph-export/depsgraph_export.py
@@ -6,10 +6,16 @@
 wm.obj_export, and asserts the exported vertex count equals the EVALUATED
 (modifier-applied) count and is strictly greater than the base.
 
+``--unevaluated`` exports with ``apply_modifiers=False`` and still asserts
+the OBJ vertex count equals the depsgraph-evaluated mesh. That is the
+falsifier (``--same-axis`` in export-preset-axis). ``--obj`` is a path
+selector, not a falsifier.
+
 By default it runs only the correctness check (no render) — the CI smoke
 check. Pass --output to also render a still:
 
     blender --background --python depsgraph_export.py --                 # check only
+    blender --background --python depsgraph_export.py -- --unevaluated   # must fail
     blender --background --python depsgraph_export.py -- --output d.png  # + render
 """
 import bpy, bmesh, sys, os, math, argparse, tempfile
@@ -35,7 +41,7 @@ def build():
     return obj
 
 
-def check(obj, obj_path):
+def check(obj, obj_path, unevaluated=False):
     base = len(obj.data.vertices)
 
     # depsgraph lifetime contract: evaluate, read, then release with to_mesh_clear
@@ -48,7 +54,11 @@ def check(obj, obj_path):
     out = obj_path or os.path.join(tempfile.gettempdir(), "depsgraph_export.obj")
     os.makedirs(os.path.dirname(os.path.abspath(out)) or ".", exist_ok=True)
     # obj_export writes the evaluated (modifier-applied) geometry by default
-    bpy.ops.wm.obj_export(filepath=out, export_selected_objects=False)
+    bpy.ops.wm.obj_export(
+        filepath=out,
+        export_selected_objects=False,
+        apply_modifiers=not unevaluated,
+    )
     if not (os.path.exists(out) and os.path.getsize(out) > 0):
         print("ERROR: no OBJ written", file=sys.stderr)
         return 4
@@ -207,10 +217,12 @@ def main():
                    help="render engine for --output (cycles for GPU-less hosts)")
     p.add_argument("--obj", default=None,
                    help="optional: write the exported OBJ here (else a temp path)")
+    p.add_argument("--unevaluated", action="store_true",
+                   help="export with apply_modifiers=False (must fail)")
     args = p.parse_args(argv)
 
     obj = build()
-    code = check(obj, args.obj)
+    code = check(obj, args.obj, unevaluated=args.unevaluated)
     if code:
         return code
 
diff --git a/examples/driver-wave/README.md b/examples/driver-wave/README.md
index 9b590a1..b7bc6f1 100644
--- a/examples/driver-wave/README.md
+++ b/examples/driver-wave/README.md
@@ -21,12 +21,30 @@ open. Headless, registering before driver creation (as here) is enough.
 # Cheap correctness check (no render) — the CI check:
 blender --background --python driver_wave.py --
 
+# Falsifier: constant 1.0 expression. Must exit non-zero.
+blender --background --python driver_wave.py -- --flat-expr
+
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
 blender --background --python driver_wave.py -- --output driver.png
 blender --background --python driver_wave.py -- --output driver.png --engine cycles
 ```
 
-It exits non-zero on failure (driven value wrong, or the flush-back disagreed). The
-`blender-smoke` workflow runs the check on Blender 5.2 LTS and 4.5 LTS.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it. `10` is the shared framing helper.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | Evaluated Z scale ≠ `wave_scale` (`--flat-expr` lands here) |
+| 4 | Original datablock was not flushed |
+| 6 | `--output` produced no file |
+| 10 | Gallery framing 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 `--flat-expr`.
 
-The `--output` render path additionally measures framing against the Layer 1 band via `examples/gallery_framing.py` (exit 10 on violation) before writing the still.
diff --git a/examples/driver-wave/driver_wave.py b/examples/driver-wave/driver_wave.py
index f1f0b7a..e6b5b7f 100644
--- a/examples/driver-wave/driver_wave.py
+++ b/examples/driver-wave/driver_wave.py
@@ -8,10 +8,14 @@
 for display, so both must agree). Asserts both against the closed-form
 profile. Exits non-zero on failure.
 
+``--flat-expr`` drives Z scale with ``1.0`` and still asserts ``wave_scale``.
+That is the falsifier (``--same-axis`` in export-preset-axis).
+
 By default it runs only the correctness check (no render) — the CI smoke
 check. Pass --output to also render a still:
 
     blender --background --python driver_wave.py --                 # check only
+    blender --background --python driver_wave.py -- --flat-expr      # must fail
     blender --background --python driver_wave.py -- --output d.png  # + render
 """
 import bpy, bmesh, sys, os, math, argparse
@@ -31,7 +35,7 @@ def wave_scale(i):
     return 1.4 + math.sin(i * 0.6)
 
 
-def build_columns():
+def build_columns(flat_expr=False):
     bpy.ops.wm.read_factory_settings(use_empty=True)
     # driver_namespace entries do not persist in .blend files; real add-ons
     # re-register them from a load_post handler. Headless, registering before
@@ -54,7 +58,7 @@ def build_columns():
         obj.scale = (BASE, BASE, 1.0)
         fcu = obj.driver_add("scale", 2)
         fcu.driver.type = 'SCRIPTED'
-        fcu.driver.expression = f"wave_scale({i})"
+        fcu.driver.expression = "1.0" if flat_expr else f"wave_scale({i})"
         bpy.context.collection.objects.link(obj)
         objs.append(obj)
     return objs
@@ -191,9 +195,11 @@ def main():
     p.add_argument("--output", default=None, help="optional: render a still PNG here")
     p.add_argument("--engine", default="eevee", choices=("eevee", "cycles"),
                    help="render engine for --output (cycles for GPU-less hosts)")
+    p.add_argument("--flat-expr", action="store_true",
+                   help="drive Z scale with 1.0 (must fail)")
     args = p.parse_args(argv)
 
-    objs = build_columns()
+    objs = build_columns(flat_expr=args.flat_expr)
     code = check(objs)
     if code:
         return code
diff --git a/examples/gltf-skin-roundtrip/README.md b/examples/gltf-skin-roundtrip/README.md
index 084315e..a698837 100644
--- a/examples/gltf-skin-roundtrip/README.md
+++ b/examples/gltf-skin-roundtrip/README.md
@@ -53,11 +53,44 @@ same curl, same glowing stinger — proof the skin rode the format through.
 # Cheap correctness check (no render) — the CI check:
 blender --background --python gltf_skin_roundtrip.py --
 
+# Falsifier: export_skins=False. Must exit non-zero.
+blender --background --python gltf_skin_roundtrip.py -- --no-skins
+
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
 blender --background --python gltf_skin_roundtrip.py -- --output scorp.png
 blender --background --python gltf_skin_roundtrip.py -- --output scorp.png --engine cycles
 ```
 
-It exits non-zero on failure (missing skin, joint drift, weight-sum drift,
-skeleton drift, weight excursion, or deformation excursion). The
-`blender-smoke` workflow runs the check on Blender 5.2 LTS and 4.5 LTS.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | Exporter RNA missing expected kwargs |
+| 4 | Vertex group count ≠ bone count |
+| 5 | Disk skins ≠ 1 (`--no-skins` lands here) |
+| 6 | Skin joints ≠ bone names |
+| 7 | Missing JOINTS_0/WEIGHTS_0, or accessor length mismatch |
+| 8 | Disk weight sums off 1.0 |
+| 9 | Disk verts exceed evaluated loops |
+| 10 | Armature count after import ≠ 1 |
+| 11 | Bone count drifted |
+| 12 | Named bone lost |
+| 13 | Bone parent drifted |
+| 14 | Rest matrices drifted |
+| 15 | Skinned mesh count after import ≠ 1 |
+| 16 | Re-import vert count ≠ disk |
+| 17 | Vertex group names drifted |
+| 18 | Weight round-trip drifted |
+| 19 | Deformation round-trip drifted |
+| 20 | `--output` produced no file |
+
+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 `--no-skins`.
+
diff --git a/examples/gltf-skin-roundtrip/gltf_skin_roundtrip.py b/examples/gltf-skin-roundtrip/gltf_skin_roundtrip.py
index 2b6e903..f8ee5cd 100644
--- a/examples/gltf-skin-roundtrip/gltf_skin_roundtrip.py
+++ b/examples/gltf-skin-roundtrip/gltf_skin_roundtrip.py
@@ -24,10 +24,14 @@
 The skins pipeline is stable between Blender 4.5 LTS and 5.1 (exporter RNA
 is byte-identical, verified on both) — the example runs identically on both.
 
+``--no-skins`` exports with ``export_skins=False`` and still asserts one
+skin on disk. That is the falsifier (``--same-axis`` in export-preset-axis).
+
 By default it runs only the correctness check (no render) — the CI smoke
 check. Pass --output to also render a still:
 
     blender --background --python gltf_skin_roundtrip.py --                 # check only
+    blender --background --python gltf_skin_roundtrip.py -- --no-skins      # must fail
     blender --background --python gltf_skin_roundtrip.py -- --output s.png  # + render
 """
 import bpy, bmesh, sys, os, math, json, struct, shutil, tempfile, argparse
@@ -247,7 +251,7 @@ def accessor_uints(idx, ncomp, ctype):
     return g, accessor_floats, accessor_uints
 
 
-def check(obj, arm, part_of):
+def check(obj, arm, part_of, no_skins=False):
     me = obj.data
     exp_props = {p.identifier for p in bpy.ops.export_scene.gltf.get_rna_type().properties}
     missing = [k for k in EXPORT_KWARGS if k not in exp_props]
@@ -290,7 +294,10 @@ def weight_map(o):
     tmp = tempfile.mkdtemp(prefix="gltf_skin_")
     try:
         path = os.path.join(tmp, "scorp.gltf").replace("\\", "/")
-        bpy.ops.export_scene.gltf(filepath=path, **EXPORT_KWARGS)
+        kw = dict(EXPORT_KWARGS)
+        if no_skins:
+            kw["export_skins"] = False
+        bpy.ops.export_scene.gltf(filepath=path, **kw)
 
         # contract 1 (on disk): the skin carries every bone, joints named
         g, acc_f, acc_u = read_gltf(path)
@@ -556,6 +563,8 @@ def main():
     p.add_argument("--output", default=None, help="optional: render a still PNG here")
     p.add_argument("--engine", default="eevee", choices=("eevee", "cycles"),
                    help="render engine for --output (cycles for GPU-less hosts)")
+    p.add_argument("--no-skins", action="store_true",
+                   help="export with export_skins=False (must fail)")
     args = p.parse_args(argv)
 
     bpy.ops.wm.read_factory_settings(use_empty=True)
@@ -565,7 +574,7 @@ def main():
     assign_weights(obj, part_of)
     arm = build_rig(obj)
     bpy.context.view_layer.update()
-    code = check(obj, arm, part_of)
+    code = check(obj, arm, part_of, no_skins=args.no_skins)
     if code:
         return code
 
diff --git a/examples/parent-inverse-orrery/README.md b/examples/parent-inverse-orrery/README.md
index f4ede38..b2ca463 100644
--- a/examples/parent-inverse-orrery/README.md
+++ b/examples/parent-inverse-orrery/README.md
@@ -24,11 +24,32 @@ land exactly on their closed-form orbit positions after the pivots spin.
 # Cheap correctness check (no render) — the CI check:
 blender --background --python parent_inverse_orrery.py --
 
+# Falsifier: parent without MPI. Must exit non-zero (orbit closed form).
+blender --background --python parent_inverse_orrery.py -- --skip-mpi
+
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
 blender --background --python parent_inverse_orrery.py -- --output orrery.png
 blender --background --python parent_inverse_orrery.py -- --output orrery.png --engine cycles
 ```
 
-It exits non-zero on failure (no jump from the trap, keep-world error, stale-matrix
-contract broken, or an orbit off its closed form). The `blender-smoke` workflow runs the
-check on Blender 5.2 LTS and 4.5 LTS.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | Bare parenting did not jump |
+| 4 | Keep-world idiom off |
+| 5 | Stale `matrix_world` contract broken |
+| 6 | Planet off closed-form orbit (`--skip-mpi` lands here) |
+| 7 | Moon off closed-form orbit |
+| 8 | `--output` produced no file |
+
+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 `--skip-mpi`.
+
diff --git a/examples/parent-inverse-orrery/parent_inverse_orrery.py b/examples/parent-inverse-orrery/parent_inverse_orrery.py
index d24fc64..ed48678 100644
--- a/examples/parent-inverse-orrery/parent_inverse_orrery.py
+++ b/examples/parent-inverse-orrery/parent_inverse_orrery.py
@@ -15,10 +15,15 @@
 every planet and the moon must land on the closed-form orbit position
 (rotation about the column axis, composed per hierarchy level).
 
+``--skip-mpi`` parents without ``matrix_parent_inverse`` and still asserts
+closed-form orbits. That is the falsifier (``--same-axis`` in
+export-preset-axis).
+
 By default it runs only the correctness check (no render) — the CI smoke
 check. Pass --output to also render a still:
 
     blender --background --python parent_inverse_orrery.py --                   # check only
+    blender --background --python parent_inverse_orrery.py -- --skip-mpi        # must fail
     blender --background --python parent_inverse_orrery.py -- --output o.png    # + render
 """
 import bpy, bmesh, sys, os, math, argparse
@@ -72,13 +77,14 @@ def empty(name, location):
     return obj
 
 
-def parent_keep_world(child, parent):
+def parent_keep_world(child, parent, skip_mpi=False):
     """The idiom this example witnesses: parent without moving the child."""
     child.parent = parent
-    child.matrix_parent_inverse = parent.matrix_world.inverted()
+    if not skip_mpi:
+        child.matrix_parent_inverse = parent.matrix_world.inverted()
 
 
-def build_orrery():
+def build_orrery(skip_mpi=False):
     """Author the whole hierarchy with bpy.data (no object-mode operators)."""
     bpy.ops.wm.read_factory_settings(use_empty=True)
 
@@ -100,8 +106,8 @@ def build_orrery():
         # everything is placed at its theta=0 WORLD position first, then
         # parented with the keep-world idiom -- nothing may move here
         bpy.context.view_layer.update()
-        parent_keep_world(arm, pivot)
-        parent_keep_world(planet, pivot)
+        parent_keep_world(arm, pivot, skip_mpi=skip_mpi)
+        parent_keep_world(planet, pivot, skip_mpi=skip_mpi)
         rig["planets"][name] = {
             "pivot": pivot, "planet": planet, "angle": math.radians(angle),
             "p0": Vector((radius, 0.0, height)),
@@ -116,9 +122,9 @@ def build_orrery():
     moon = sphere("Moon", MOON_R)
     moon.location = pc0 + Vector((MOON_OFFSET, 0.0, 0.0))
     bpy.context.view_layer.update()
-    parent_keep_world(moon_pivot, host["planet"])
-    parent_keep_world(rod, moon_pivot)
-    parent_keep_world(moon, moon_pivot)
+    parent_keep_world(moon_pivot, host["planet"], skip_mpi=skip_mpi)
+    parent_keep_world(rod, moon_pivot, skip_mpi=skip_mpi)
+    parent_keep_world(moon, moon_pivot, skip_mpi=skip_mpi)
     rig["moon"] = {"pivot": moon_pivot, "moon": moon,
                    "angle": math.radians(MOON_ANGLE), "pc0": pc0,
                    "m0": pc0 + Vector((MOON_OFFSET, 0.0, 0.0))}
@@ -323,9 +329,11 @@ def main():
     p.add_argument("--output", default=None, help="optional: render a still PNG here")
     p.add_argument("--engine", default="eevee", choices=("eevee", "cycles"),
                    help="render engine for --output (cycles for GPU-less hosts)")
+    p.add_argument("--skip-mpi", action="store_true",
+                   help="parent without matrix_parent_inverse (must fail)")
     args = p.parse_args(argv)
 
-    rig = build_orrery()
+    rig = build_orrery(skip_mpi=args.skip_mpi)
     code = check(rig)
     if code:
         return code
diff --git a/examples/prop-origin-transform/README.md b/examples/prop-origin-transform/README.md
index 063514d..ae73d9a 100644
--- a/examples/prop-origin-transform/README.md
+++ b/examples/prop-origin-transform/README.md
@@ -46,11 +46,31 @@ color — carries the proof. Check closed forms are unchanged.
 
 ```bash
 blender --background --python prop_origin_transform.py --
+blender --background --python prop_origin_transform.py -- --skip-mpi
 blender --background --python prop_origin_transform.py -- --output origin.png
 blender --background --python prop_origin_transform.py -- --output origin.png --engine cycles
 ```
 
-Exits non-zero on failure. The `blender-smoke` workflow runs the check on
-Blender 5.2 LTS and 4.5 LTS. The `--output` render path additionally measures
-framing against the Layer 1 band via `examples/gallery_framing.py` (exit 10
-on violation) before writing the still.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it. `10` is the shared framing helper.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | Stale `matrix_world` contract broken |
+| 4 | World bbox moved across bake |
+| 5 | Scale after bake is not (1,1,1) |
+| 6 | Origin not at local base center |
+| 7 | Bare parenting did not jump |
+| 8 | MPI did not restore world location (`--skip-mpi` lands here) |
+| 9 | `--output` produced no file |
+| 10 | Gallery framing 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 `--skip-mpi`.
+
diff --git a/examples/prop-origin-transform/prop_origin_transform.py b/examples/prop-origin-transform/prop_origin_transform.py
index e081179..9d0af98 100644
--- a/examples/prop-origin-transform/prop_origin_transform.py
+++ b/examples/prop-origin-transform/prop_origin_transform.py
@@ -7,10 +7,14 @@
 `parent-inverse-orrery` (MPI idiom + stale `matrix_world`) without retreading
 orbits — subject is a street utility pedestal with a bolted conduit accessory.
 
+``--skip-mpi`` parents the accessory without MPI and still asserts the restore.
+That is the falsifier (``--same-axis`` in export-preset-axis).
+
 By default it runs only the correctness check (no render). Pass --output
 to also render a still:
 
     blender --background --python prop_origin_transform.py --
+    blender --background --python prop_origin_transform.py -- --skip-mpi
     blender --background --python prop_origin_transform.py -- --output o.png
 """
 import bpy, bmesh, sys, os, math, argparse
@@ -257,7 +261,7 @@ def bake_prop(prop):
     return before, after
 
 
-def check(prop, acc):
+def check(prop, acc, skip_mpi=False):
     """Assert origin/scale bake + MPI accessory contract. Exit 3–8 on failure."""
     view_layer = bpy.context.view_layer
 
@@ -341,8 +345,9 @@ def check(prop, acc):
         )
         return 7
 
-    acc.matrix_parent_inverse = prop.matrix_world.inverted()
-    view_layer.update()
+    if not skip_mpi:
+        acc.matrix_parent_inverse = prop.matrix_world.inverted()
+        view_layer.update()
     err = (acc.matrix_world.translation - w0).length
     print(f"mpi_restore_err={err:.3e}")
     if err > MPI_EPS:
@@ -608,11 +613,13 @@ def main():
     p = argparse.ArgumentParser()
     p.add_argument("--output", default=None)
     p.add_argument("--engine", default="eevee", choices=("eevee", "cycles"))
+    p.add_argument("--skip-mpi", action="store_true",
+                   help="parent the accessory without MPI (must fail)")
     args = p.parse_args(argv)
 
     print(f"binary version: {bpy.app.version} ({bpy.app.version_string})")
     sc, prop, acc = build_scene()
-    code = check(prop, acc)
+    code = check(prop, acc, skip_mpi=args.skip_mpi)
     if code:
         return code
 
diff --git a/examples/shape-key-blend/README.md b/examples/shape-key-blend/README.md
index b00191f..729b634 100644
--- a/examples/shape-key-blend/README.md
+++ b/examples/shape-key-blend/README.md
@@ -16,10 +16,34 @@ mesh stays at Basis; every evaluated vertex matches the closed-form blend
 # Cheap correctness check (no render) — the CI check:
 blender --background --python shape_key_blend.py --
 
+# Falsifier: Tall.value = 0. Must exit non-zero.
+blender --background --python shape_key_blend.py -- --zero-blend
+
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
 blender --background --python shape_key_blend.py -- --output blend.png
 blender --background --python shape_key_blend.py -- --output blend.png --engine cycles
 ```
 
-It exits non-zero on failure (missing keys, wrong value, per-vert blend mismatch, or
-flare miss). The `blender-smoke` workflow runs the check on Blender 5.2 LTS and 4.5 LTS.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | No shape keys on mesh |
+| 4 | Key names ≠ Basis, Tall |
+| 5 | Tall.value ≠ 0.5 (`--zero-blend` lands here) |
+| 6 | Undeformed `mesh.vertices` not at Basis |
+| 7 | Evaluated vert off closed-form blend |
+| 8 | Evaluated Z span off closed form |
+| 9 | Top flare off closed form |
+| 10 | `--output` produced no file |
+
+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 `--zero-blend`.
+
diff --git a/examples/shape-key-blend/shape_key_blend.py b/examples/shape-key-blend/shape_key_blend.py
index 5bc58dc..35fdd5c 100644
--- a/examples/shape-key-blend/shape_key_blend.py
+++ b/examples/shape-key-blend/shape_key_blend.py
@@ -10,10 +10,14 @@
 The Tall key both lifts and flares the top face, so the silhouette is a
 truncated pyramid — clearly a blend, not a uniformly scaled box.
 
+``--zero-blend`` sets Tall.value to 0 and still asserts the 0.5 closed form.
+That is the falsifier (``--same-axis`` in export-preset-axis).
+
 By default it runs only the correctness check (no render) — the CI smoke
 check. Pass --output to also render a still:
 
     blender --background --python shape_key_blend.py --                 # check only
+    blender --background --python shape_key_blend.py -- --zero-blend    # must fail
     blender --background --python shape_key_blend.py -- --output s.png  # + render
 """
 import bpy, bmesh, sys, os, math, argparse
@@ -28,7 +32,7 @@
 EXPECT_TOP_HALF = HALF + BLEND * FLARE  # |x| and |y| of top verts
 
 
-def build():
+def build(zero_blend=False):
     bpy.ops.wm.read_factory_settings(use_empty=True)
     me = bpy.data.meshes.new("Block")
     bm = bmesh.new()
@@ -51,7 +55,7 @@ def build():
             # flare top face outward so the blend reads as a taper, not a box
             co.x = math.copysign(HALF + FLARE, co.x)
             co.y = math.copysign(HALF + FLARE, co.y)
-    tall.value = BLEND
+    tall.value = 0.0 if zero_blend else BLEND
     return obj
 
 
@@ -245,9 +249,11 @@ def main():
     p.add_argument("--output", default=None, help="optional: render a still PNG here")
     p.add_argument("--engine", default="eevee", choices=("eevee", "cycles"),
                    help="render engine for --output (cycles for GPU-less hosts)")
+    p.add_argument("--zero-blend", action="store_true",
+                   help="set Tall.value to 0 (must fail)")
     args = p.parse_args(argv)
 
-    obj = build()
+    obj = build(zero_blend=args.zero_blend)
     code = check(obj)
     if code:
         return code
diff --git a/examples/soccer-ball-goldberg/README.md b/examples/soccer-ball-goldberg/README.md
index 57730ec..e6b815b 100644
--- a/examples/soccer-ball-goldberg/README.md
+++ b/examples/soccer-ball-goldberg/README.md
@@ -68,11 +68,37 @@ inverts with it: white pentagons on a black ball, wrong on sight.
 # Cheap correctness check (no render) — the CI check:
 blender --background --python soccer_ball_goldberg.py --
 
+# Falsifier: swap pentagon/hexagon slots. Must exit non-zero.
+blender --background --python soccer_ball_goldberg.py -- --invert-bind
+
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
 blender --background --python soccer_ball_goldberg.py -- --output ball.png
 blender --background --python soccer_ball_goldberg.py -- --output ball.png --engine cycles
 ```
 
-It exits non-zero on failure (topology, census, degree, edge uniformity,
-planarity, circumsphere, or panel binding). The `blender-smoke` workflow runs
-the check on Blender 5.2 LTS and 4.5 LTS.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | Topology ≠ 60/90/32 |
+| 4 | Euler characteristic ≠ 2 |
+| 5 | Face census ≠ 12 pentagons + 20 hexagons |
+| 6 | Vertex degree not uniform 3; also `--output` produced no file |
+| 7 | Non-manifold edges |
+| 8 | Edge lengths not uniform |
+| 9 | Face planarity off |
+| 10 | Centroid off origin |
+| 11 | Circumradius not uniform |
+| 12 | Panel material count ≠ 2 |
+| 13 | Panel binding not by vertex count (`--invert-bind` lands here) |
+
+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 `--invert-bind`.
+
diff --git a/examples/soccer-ball-goldberg/soccer_ball_goldberg.py b/examples/soccer-ball-goldberg/soccer_ball_goldberg.py
index c880cbd..16ad3e8 100644
--- a/examples/soccer-ball-goldberg/soccer_ball_goldberg.py
+++ b/examples/soccer-ball-goldberg/soccer_ball_goldberg.py
@@ -13,6 +13,7 @@
 check. Pass --output to also render a still:
 
     blender --background --python soccer_ball_goldberg.py --                 # check only
+    blender --background --python soccer_ball_goldberg.py -- --invert-bind   # must fail
     blender --background --python soccer_ball_goldberg.py -- --output b.png  # + render
 """
 import bpy, bmesh, sys, os, math, argparse
@@ -67,7 +68,7 @@ def _fan_edges(bv):
         prev_face, current = face, nxt
 
 
-def build_ball():
+def build_ball(invert_bind=False):
     """Truncate a bmesh icosphere at 1/3 per edge into the Goldberg ball.
 
     The icosphere is the topology source: cut points are computed per edge,
@@ -150,7 +151,8 @@ def near(i, j):
     # builder that assigns "first 12 faces black" passes only by luck of
     # bmesh face ordering, and the check below must catch it
     for poly in me.polygons:
-        poly.material_index = 1 if len(poly.vertices) == 5 else 0
+        pent = len(poly.vertices) == 5
+        poly.material_index = (0 if pent else 1) if invert_bind else (1 if pent else 0)
     return obj
 
 
@@ -392,9 +394,11 @@ def main():
     p.add_argument("--output", default=None, help="optional: render a still PNG here")
     p.add_argument("--engine", default="eevee", choices=("eevee", "cycles"),
                    help="render engine for --output (cycles for GPU-less hosts)")
+    p.add_argument("--invert-bind", action="store_true",
+                   help="swap pentagon/hexagon material slots (must fail)")
     args = p.parse_args(argv)
 
-    obj = build_ball()
+    obj = build_ball(invert_bind=args.invert_bind)
     code = check(obj)
     if code:
         return code
diff --git a/examples/temp-override-join/README.md b/examples/temp-override-join/README.md
index 3910b11..3510424 100644
--- a/examples/temp-override-join/README.md
+++ b/examples/temp-override-join/README.md
@@ -19,11 +19,32 @@ leaves only step 0 and the Z span fails.
 # Cheap correctness check (no render) — the CI check:
 blender --background --python temp_override_join.py --
 
+# Falsifier: join without temp_override. Must exit non-zero.
+blender --background --python temp_override_join.py -- --no-override
+
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
 blender --background --python temp_override_join.py -- --output join.png
 blender --background --python temp_override_join.py -- --output join.png --engine cycles
 ```
 
-It exits non-zero on failure (wrong object count, topology mismatch, sources still alive,
-or incomplete Z span). The `blender-smoke` workflow runs the check on Blender 5.2 LTS and
-4.5 LTS.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | Mesh object count after join ≠ 1 (`--no-override` lands here) |
+| 4 | Joined target is not the sole remaining mesh |
+| 5 | Topology ≠ 24 verts / 18 faces |
+| 6 | Source objects still present |
+| 7 | Local Z span did not cover all steps |
+| 8 | `--output` produced no file |
+
+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 `--no-override`.
+
diff --git a/examples/temp-override-join/temp_override_join.py b/examples/temp-override-join/temp_override_join.py
index eaff520..f178d89 100644
--- a/examples/temp-override-join/temp_override_join.py
+++ b/examples/temp-override-join/temp_override_join.py
@@ -8,10 +8,15 @@
 that only the target remains, and that the local Z span spans all three steps
 (proving every source contributed geometry).
 
+``--no-override`` calls ``object.join`` without ``temp_override``. If the
+operator raises, that is caught and the existing object-count check still
+runs. That is the falsifier (``--same-axis`` in export-preset-axis).
+
 By default it runs only the correctness check (no render) — the CI smoke
 check. Pass --output to also render a still:
 
     blender --background --python temp_override_join.py --                 # check only
+    blender --background --python temp_override_join.py -- --no-override   # must fail
     blender --background --python temp_override_join.py -- --output j.png  # + render
 """
 import bpy, bmesh, sys, os, math, argparse
@@ -198,12 +203,22 @@ def main():
     p.add_argument("--output", default=None, help="optional: render a still PNG here")
     p.add_argument("--engine", default="eevee", choices=("eevee", "cycles"),
                    help="render engine for --output (cycles for GPU-less hosts)")
+    p.add_argument("--no-override", action="store_true",
+                   help="join without temp_override (must fail)")
     args = p.parse_args(argv)
 
     objs = build_cubes()
     target, sources = objs[0], objs[1:]
     source_names = [s.name for s in sources]
-    joined = join_with_temp_override(target, sources)
+    if args.no_override:
+        try:
+            bpy.ops.object.join()
+        except RuntimeError as exc:
+            print(f"join without override: {type(exc).__name__}: {exc}",
+                  file=sys.stderr)
+        joined = target
+    else:
+        joined = join_with_temp_override(target, sources)
     code = check(joined, source_names)
     if code:
         return code
diff --git a/examples/vertex-weight-limit/README.md b/examples/vertex-weight-limit/README.md
index c8d2ae7..b481037 100644
--- a/examples/vertex-weight-limit/README.md
+++ b/examples/vertex-weight-limit/README.md
@@ -49,13 +49,35 @@ limited weights still deform as authored.
 # Cheap correctness check (no render) — the CI check:
 blender --background --python vertex_weight_limit.py --
 
+# Falsifier: skip the 4-influence prune. Must exit non-zero.
+blender --background --python vertex_weight_limit.py -- --skip-limit
+
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
 blender --background --python vertex_weight_limit.py -- --output arm.png
 blender --background --python vertex_weight_limit.py -- --output arm.png --engine cycles
 ```
 
-It exits non-zero on failure (vacuous authoring, a vertex over the cap, broken
-weight sums, pose damaged by pruning, LBS drift, or a moved Root mount). The
-`blender-smoke` workflow runs the check on Blender 5.2 LTS and 4.5 LTS.
+## Exit codes
+
+Per-script sequential checks. `9` is a valid check code; there is no rule
+against it. `10` is the shared framing helper; it is also the missing-render
+code.
+
+| Code | Meaning |
+| --- | --- |
+| 0 | Success |
+| 1 | Uncaught exception (FATAL wrapper) |
+| 2 | argparse / usage |
+| 3 | Pre-limit max influences ≠ 5 |
+| 4 | Vertex over the 4-influence cap (`--skip-limit` lands here) |
+| 5 | Limit changed nothing |
+| 6 | Weight sums off 1.0 after renormalize |
+| 7 | Pose damaged by pruning, or evaluated vert count changed |
+| 8 | Evaluated mesh off LBS over limited weights |
+| 9 | Root-weighted mount moved |
+| 10 | Gallery framing violation; also `--output` produced no file |
+
+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 `--skip-limit`.
 
-The `--output` render path additionally measures framing against the Layer 1 band via `examples/gallery_framing.py` (exit 10 on violation) before writing the still.
diff --git a/examples/vertex-weight-limit/vertex_weight_limit.py b/examples/vertex-weight-limit/vertex_weight_limit.py
index e19a778..3a61650 100644
--- a/examples/vertex-weight-limit/vertex_weight_limit.py
+++ b/examples/vertex-weight-limit/vertex_weight_limit.py
@@ -23,10 +23,15 @@
 between Blender 4.5 LTS and 5.1 — the example runs identically on both, which
 is itself the version witness.
 
+``--skip-limit`` leaves the five-influence flex weights in place and still
+asserts the engine cap. That is the falsifier (``--same-axis`` in
+export-preset-axis).
+
 By default it runs only the correctness check (no render) — the CI smoke
 check. Pass --output to also render a still:
 
     blender --background --python vertex_weight_limit.py --                 # check only
+    blender --background --python vertex_weight_limit.py -- --skip-limit    # must fail
     blender --background --python vertex_weight_limit.py -- --output a.png  # + render
 """
 import bpy, bmesh, sys, os, math, argparse
@@ -262,7 +267,7 @@ def eval_positions(obj):
         ob_eval.to_mesh_clear()
 
 
-def check(obj, arm, groups, pose_before):
+def check(obj, arm, groups, pose_before, skip_limit=False):
     me = obj.data
 
     # pre-limit witness: the flex cuffs really carry five influences
@@ -274,16 +279,17 @@ def check(obj, arm, groups, pose_before):
 
     # the limit, through the data API: keep top-4, drop the rest, renormalize
     changed = 0
-    for v in me.vertices:
-        gs = sorted(v.groups, key=lambda g: -g.weight)
-        if len(gs) > MAX_INFLUENCES:
-            changed += 1
-        for g in gs[MAX_INFLUENCES:]:
-            groups[BONES[g.group]].remove([v.index])
-        kept = [g for g in v.groups]
-        total = sum(g.weight for g in kept)
-        for g in kept:
-            groups[BONES[g.group]].add([v.index], g.weight / total, 'REPLACE')
+    if not skip_limit:
+        for v in me.vertices:
+            gs = sorted(v.groups, key=lambda g: -g.weight)
+            if len(gs) > MAX_INFLUENCES:
+                changed += 1
+            for g in gs[MAX_INFLUENCES:]:
+                groups[BONES[g.group]].remove([v.index])
+            kept = [g for g in v.groups]
+            total = sum(g.weight for g in kept)
+            for g in kept:
+                groups[BONES[g.group]].add([v.index], g.weight / total, 'REPLACE')
 
     # contract 1: no vertex exceeds the engine limit
     post_max = max(len(v.groups) for v in me.vertices)
@@ -481,6 +487,8 @@ def main():
     p.add_argument("--output", default=None, help="optional: render a still PNG here")
     p.add_argument("--engine", default="eevee", choices=("eevee", "cycles"),
                    help="render engine for --output (cycles for GPU-less hosts)")
+    p.add_argument("--skip-limit", action="store_true",
+                   help="skip the 4-influence prune (must fail)")
     args = p.parse_args(argv)
 
     bpy.ops.wm.read_factory_settings(use_empty=True)
@@ -491,7 +499,7 @@ def main():
     arm = build_rig(obj)
     bpy.context.view_layer.update()
     pose_before = eval_positions(obj)
-    code = check(obj, arm, groups, pose_before)
+    code = check(obj, arm, groups, pose_before, skip_limit=args.skip_limit)
     if code:
         return code