git:20260926.9ac7861 to git:20261017.88ccf82

- Expert hard surface is controlled light on edges: every edge catches a highlight from a bevel or a support loop, flat faces read perfectly flat, and cuts stay editable until the design is settled. The experts disagree on method (n-gons and booleans vs quad cages and subdivision), not on the checks: order of operations, cutter hygiene, planar faces, a shiny matcap orbit. The agent builds the stack with the toolkit and lets the measurable gates find what a human finds by orbiting. If a sibling skill named here is missing from your available skills, ask the user to install it (`npx skills add scenario-labs/skills --skill <name>`); unattended, proceed from tool schemas and flag the gap.

- **REQUIRED BACKGROUND:** scenario-blender-expert (execution channel, review loop, 5.2 API changes). Toolkit: [`scripts/bx_hardsurface.py`](scripts/bx_hardsurface.py) (`import sys; sys.path.append("<skills>/scenario-blender-hard-surface/scripts"); import bx_hardsurface as HS`), world-space meters, stock Blender only.

- - **Cut first, bevel after, normals last.** Booleans above the angle-limited micro bevel, Weighted Normal at the very bottom, a late Mirror above it (Ryuu [00:26:26], [00:28:37]; du Mont [00:19:46]). In 5.2 a pinned modifier keeps its relative order inside the pinned group and new modifiers land above it, so pin bottom-up: `HS.order_stack` does it and `HS.add_boolean` always lands above the tail (verified).

- - **Two bevels, two jobs** (du Mont [00:12:25] to [00:15:15]): a weight-limited design bevel (8 to 12 segments) on chosen silhouette edges before the cuts, and an angle-limited micro bevel (30 degrees, Harden Normals, Miter Outer Arc) after every cut, because no real edge is perfectly sharp (Gambrell, du Mont, Ryuu).

- - **A bevel that shrinks after a boolean is geometry, not a setting** (du Mont [00:20:18], [00:30:20]). Move the cutter well away from target edges or make it exactly coincident; keep Clamp Overlap on. Clamp Overlap limits the bevel over the whole object: a slot running 0.7 degrees off a facet edge (clamp ratio 3.8) wiped out the 3 mm bevel on a port elsewhere on the part [verified in 5.2.1]. `HS.clamp_culprits` names the cut.

- - **Every wall, step, gap and rounding facet must be wider than 2x the micro bevel width** [added, verified]: a 1 mm pocket floor, a 1.5 mm wall, a 2 mm groove with 1.5 mm bevels (a 3.1 mm one was clean) and a slot rounded in 30-degree facets all clamped the whole object's bevel.

- - **If Harden Normals or Weighted Normal changes nothing, the face is not flat** (Gambrell [00:01:06]). Flatten it; more normal modifiers will not help.

- - **Pick the school by the part, not by taste.** Planar machined parts with many cuts: n-gons + booleans + bevel + custom normals, about a quarter of the time and stays editable (Gambrell [00:18:01]). Continuous curvature, non-uniform roundness, a sculpt or bake high: quad cage + subdivision (rileyb3d, PzThree). Sharpen subD edges with support loops, not creases: 36,800 vs 3,600 triangles at equal quality (Lampel [00:05:28]).

- - **EXACT is the solver.** Gambrell's 2021 "switch to Fast" predates 5.x: Float left 16 non-manifold edges on a coplanar cutter where Exact and Manifold were clean [verified]. When Exact misbehaves the operand is broken (Ryuu [00:15:13]): an open cutter gave Exact 19 non-manifold edges and Manifold silently skipped the cut [verified].

- - **Judge in a shiny matcap and close up on every cut** (Gambrell [00:00:33], rileyb3d [00:06:32]). Whole-object sheets hide smears and shrunken bevels.

- 1. **Blockout at real size.** Primitives or bmesh, then `HS.apply_scale(ob)` (keeps children in place, flips winding on negative scale). Check proportions against a human-scale box through a long lens (du Mont [00:10:01]). GATE: scale is 1 on every object with a bevel, solidify or array; silhouette sheet reads (`bx_review.review(..., modes=("silhouette",))`).

- - A: design edges with `HS.find_edges(ob, min_angle=80, inside=...)` + `HS.set_edge_attr(ob, edges, 1.0)`, then `HS.hard_surface_stack(ob, micro_width=..., design_width=...)`.

- - B: quad cage in bmesh (few control points, square quads, rileyb3d / PzThree), then `HS.subd_stack(ob, support_width=...)` (Bevel Weight, even segments, profile 1.0, Subdivision with UV Smooth Keep Corners) or explicit `HS.support_loops`.

- GATE: `HS.stack_problems(ob) == []`; A has custom normals on the evaluated mesh.

- 3. **Cut (School A).** `HS.make_cutter(target, "BOX"|"CYLINDER"|"SLOT", size, location, ...)` builds a cutter that meets the checklist (scale 1, smooth, Cutters collection only, wire, hidden from render, parented, EXACT, wired above the tail). `HS.as_cutter` for custom shapes, `HS.slice_boolean` for Slice. Rules: extend past every surface entered; keep cutter edges far from target edges or exactly on them; offset a round cutter by half a segment against a target with the same count (same phase gave 10 non-manifold edges and streaks [verified]; `make_cutter` default); round cutter corners in facets well under the bevel angle (4+ segments per 90 degrees). GATE after each cut: `HS.cutter_report(c, target)` clean, `HS.clamp_probe(target)["ratio"] < 0.1`, a `HS.closeup` of the cut looked at.

- 4. **Design pass.** Cluster details, leave calm areas, align with neighboring features (Ryuu [00:28:37], Gambrell [00:34:15]); hide perfect intersections behind a collar (du Mont [00:39:36]); union parts that must share a bevel (Gambrell [00:18:57]). GATE: a review sheet shows intent, not noise.

- 5. **Shading pass.** `r = HS.shading_audit(ob); HS.verdict(r)`, then `HS.review([ob], out, modes=("matcap","reflect","hsgrey","wire"))` and closeups. Triage with [`references/critique.md`](references/critique.md): smear on flat faces, non-planar faces, cuts on curvature (render first: Harden + WN already shaded 24/48-segment cylinder cuts cleanly; on a sphere `HS.transfer_normals` cut the normal error p95 from 2.79 to 0.34 degrees [verified]), mirror seam (`HS.mirror_seam_fix`). GATE: verdict empty or every remaining line explained, and the closeups agree.

- 6. **School B detail and pinch check.** Even bevel segments, profile 1.0, Keep Corners (Lampel [00:11:15]); brace both sides of a ridge equally (rileyb3d [00:11:08]); outset a border ring around inset circles (PzThree [00:42:25]); turn subdivision off to debug a cage artifact (Gambrell [00:14:44]). GATE: `r["subd_cage"]` quads near 100%, no long rectangles on a cage that will be sculpted, shiny-matcap closeups free of pinches.

- 7. **Game or export.** Mid-poly: `g, tris = HS.game_version(ob, micro_segments=1)` (Triangulate with keep custom normals after WN; stays in place because it shares the cutters); glTF kept the custom normals 100% [verified]. Baked asset: the low poly and bake go to scenario-blender-retopology and scenario-blender-uv-baking. Rig or export: `HS.collapse(ob)` on a copy (du Mont [01:07:29]). GATE: tri count within budget, triangles only, matcap closeup of the game copy.

- **In code** (all in `HS.shading_audit`, readable through `HS.verdict`): scale applied; `stack_problems` empty; custom normals present when expected; 0 non-manifold edges; 0 flat-shaded faces; 0 non-planar base faces (tolerance 1e-4 x size); no smear (corner normal leaning over 3 degrees on a flat face [added]); no hard edge (over 45 degrees) smoothed across; clamp ratio under 0.1; every boolean changes the mesh; cutter reports clean (coplanar, near-parallel, thin wall, narrow gap, near-miss, rounding facets, pokes out, hygiene). School B: quads %, quad aspect, crease length. Game: `HS.tri_count`, triangles only.

- **Visual:** `HS.review` rows matcap (forms), reflect (`check_reflection_horizontal`: stripes run continuous over bevels and rounds), hsgrey (bevel highlights), wire (real boolean topology); views front, threequarter, top, low. Then one `HS.closeup(ob, point, radius, ...)` per cut in `shiny` (metal_carpaint). Look for gradient smears on flat faces, a bevel highlight broken or narrower at a cut, stretch at cut corners on curves, a butterfly on a mirror seam, subD pinches, facets on cut walls. A straight-down shiny view saturates white: use matcap or hsgrey from the top.

- - Auto Smooth is gone (4.1): `bpy.ops.object.shade_auto_smooth` adds a pinned Smooth by Angle node modifier (works headless with `temp_override`); WN, Harden Normals and Data Transfer need no Auto Smooth.

- - Bevel weights and creases are attributes `bevel_weight_edge` / `crease_edge` (4.0); the Bevel modifier reads any attribute through `edge_weight`.

- - `ob.modifiers.move(i, j)` silently refuses moves that involve pinned modifiers; `modifier_move_to_index` returns CANCELED. Unpin, move, re-pin bottom-up.

- - EXACT gives cutter-made vertices the target's vertex-group weights (verified), so vertex groups cannot keep a Data Transfer off cut walls.

- - Bool Tool, LoopTools, Extra Objects are extensions (4.2); LoopTools Circle/Flatten/Space are built in (`mesh.circularize`, `mesh.flatten`, `mesh.space_edge_loops_evenly`); Relax and Round Cube are not.

- - [`references/procedures.md`](references/procedures.md): full tested code for the three parts (panel, case both schools, barrel both schools), every audit case, game routes. Load before scripting.

- - `references/critique.md`: the rubric and triage table to judge a render and a verdict. Load at every shading pass.

- - [`references/expert-notes.md`](references/expert-notes.md): the experts' principles, disagreements and deciding conditions, with timestamps. Load when a choice is not covered here.

- - [`references/sources.md`](references/sources.md): the nine videos, who, what each is best for, best timestamps.