swatch-grid
Procedural Principled materials — metal and dielectric, the emission pattern, and the cross-version set_specular shim.
witnesses EEVEE engine-id mapping: BLENDER_EEVEE on 5.x, BLENDER_EEVEE_NEXT on 4.2–4.5.
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turntable
A slotted-actions Z-rotation turntable keyed through the cross-version channelbag path (get_channelbag_for_slot).
witnesses Slotted-actions boundary: ensure-helper channelbag on 5.x, strip.channelbag on 4.4/4.5.
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gn-sdf-remesh
A Geometry Nodes SDF remesh (MeshToSDFGrid → GridToMesh at the SDF zero-level), with a Set Material node carrying the material through the remesh.
witnesses An SDF grid is meshed with Grid to Mesh, not Volume to Mesh; GN geometry needs Set Material or it renders untextured.
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depsgraph-export
The depsgraph lifetime contract — evaluated_get().to_mesh() paired with to_mesh_clear() — measured against an OBJ export of the same object.
witnesses Exports ship evaluated geometry: the exported vertex count equals the subsurf-applied count and is strictly greater than the base mesh.
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wave-displace
Bulk vertex IO at real scale — 9,409 vertices displaced into a standing wave with one foreach_get and one foreach_set, no per-vertex access.
witnesses The bulk path is correct, not just fast: vertex count unchanged, Z span matches the wave amplitude, probe vertex matches the closed form exactly.
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driver-wave
A driver_namespace function driving sixteen column heights through SCRIPTED drivers — the sine skyline is entirely driver-evaluated.
witnesses Driven values appear after a view-layer update in two places that must agree: the evaluated copy and the original datablock the animation system flushes for display.
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bmesh-gear
A 14-tooth gear built entirely with bmesh — profile ring, face, extrude — with bm.free() in a try/finally, exactly as the ownership contract demands.
witnesses Parametric bmesh topology is exactly predictable: verts, edges, and faces match their closed forms, and every edge borders exactly two faces (watertight).
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shader-node-group
One reusable shader group declared via tree.interface.new_socket, instanced in two materials with different Tint values — two spheres, one group, two colors.
witnesses Grouping contract: interface sockets appear on every instance, both materials share one group datablock (users == 2), and per-material parameters live on the group node, not inside the tree.
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temp-override-join
Join three unit cubes into a staircase under bpy.context.temp_override — the supported replacement for the removed context.copy() dict-pass form.
witnesses temp_override actually applies: join consumes the sources, exactly one mesh remains, topology is verts = 8 × steps, and local Z spans all three steps.
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gn-instance-grid
A generative Geometry Nodes tree — Mesh Grid → Instance on Points → Realize Instances → Set Shade Smooth — attached as a NODES modifier with no Group Input geometry.
witnesses Realized instances produce closed-form topology (72 verts, 54 faces), Set Material carries Lime, and the corner instance center sits at its closed-form grid coordinate.
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shape-key-blend
A relative Tall shape key that lifts and flares the top face — authored via shape_key_add / key_blocks / .value — read back from the depsgraph-evaluated mesh.
witnesses Shape keys do not rewrite mesh.vertices: every evaluated vert matches basis + value × (key − basis), including the flared top half-extent.
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curve-bevel-arc
A beveled Bezier semicircle authored on bpy.types.Curve — splines.new('BEZIER'), bezier_points, bevel_depth, use_fill_caps — so the curve renders as a solid tube without a prior mesh conversion.
witnesses Curve tubes are curve datablocks: eight Bezier points, bevel_depth == 0.15, filled caps, and the evaluated mesh has deterministic topology (1044 verts, 1028 faces) resting on the floor.
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