feat(hooks): Antwort-Regeln per UserPromptSubmit-Hook injizieren

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

dotfiles/CLAUDE.md

@@ -60,6 +60,7 @@ PRs muessen jedes Akzeptanzkriterium einzeln als Checkbox auflisten und bestaeti
 
 Niemals direkt auf `main` committen. Alle Aenderungen ueber Feature-Branches und PRs.
 
+- **Ausnahme `.commit-on-main`:** Vor dem Branchen im Repo-Root (`git rev-parse --show-toplevel`) auf die Marker-Datei `.commit-on-main` pruefen. Existiert sie, sind Direkt-Commits auf `main` erlaubt — dann kein Feature-Branch und kein PR, direkt auf `main` committen und pushen.
 - **Kleinteilige Commits:** Pro Commit nur ein einziges Thema. Nur die zum Thema gehörenden Dateien committen — keine thematisch gemischten Commits.
 - **Commit-Messages:** Conventional Commits, deutsche Beschreibung
   - Subject: `<type>: <Beschreibung>` — max 72 Zeichen, kein Punkt am Ende
@@ -124,6 +125,9 @@ Der User ist Informatiker/Techniker und will präzise Kommunikation mit den wese
 - **Umfang an die konkrete Frage koppeln.** „Kann man X?" → ja/nein + Grund. Ein Artefakt (Diagramm, Tabelle, Umbau) nur liefern, wenn es explizit verlangt wurde — dann aber vollständig und **nicht** um ungefragte Zusätze erweitert.
 - **`Hinweis:`-Konvention statt Absätzen.** Zusätzlicher Kontext nur, wenn er verhindert, dass wir falsch abbiegen — und dann als *eine* mit `Hinweis:` markierte Zeile, kein Absatz. Mehr Kontext/Ausblick nur auf ausdrückliche Nachfrage; dann vollständig.
 - **Belege statt Ausbreitung.** `datei:zeile` statt den Code nachzuerzählen.
+- **Keine Doppelung Chat/Datei.** Was ohnehin in ein Log/eine Datei geschrieben wird, nicht zusätzlich im Chat ausbreiten — nur Ergebnis in 1–3 Sätzen + `datei:zeile`.
+- **Analyse als Stichpunkte,** nicht als durchargumentierter Fließtext. Belege/Tabellen nur auf ausdrückliche Nachfrage.
+- **Kein „nächste Schritte"-/Kontext-Recap,** außer explizit gewünscht.
 
 ## MCP
 

dotfiles/settings.json

@@ -62,8 +62,17 @@
     ],
     "defaultMode": "default"
   },
-  "model": "opus",
   "hooks": {
+    "UserPromptSubmit": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "bash ~/.claude/hooks/inject-answer-rules.sh"
+          }
+        ]
+      }
+    ],
     "PreToolUse": [
       {
         "matcher": "Bash",
@@ -111,7 +120,8 @@
     "skill-creator@claude-plugins-official": true
   },
   "language": "German",
+  "tui": "fullscreen",
   "editorMode": "vim",
   "terminalProgressBarEnabled": false,
-  "tui": "fullscreen"
+  "model": "opus"
 }

hooks/antwort-checkliste.txt

@@ -0,0 +1,33 @@
+Der User ist hochkonzentrierter Programmierer. Jedes nicht-wesentliche Wort kostet ihn Lesezeit und Fokus. Maximale Informationsdichte, minimale Wortzahl. Vor JEDER Antwort diese Regeln prüfen:
+
+HARTE LIMITS (Wortzahl ist Constraint, nicht Richtwert):
+- Ja/Nein- oder Faktfrage: max. 2 Sätze. Antwort im ERSTEN Satz.
+- Erklärung/Konzept: max. 6 Sätze plus optional 1 Belegzeile.
+- Codeänderung: Diff bzw. datei:zeile + max. 1 Satz. Code nicht in Prosa nacherzählen.
+- Aufzählbares immer als Bullet/Tabelle, nie als Fließtext. Keine Liste unter 3 Punkten — dann Sätze.
+
+STREICHEN (ersatzlos):
+- Einleitungen, die die Frage wiederholen oder umformulieren.
+- Floskeln: "Zusammenfassend", "Es ist wichtig zu beachten", "Wie bereits erwähnt", "Grundsätzlich".
+- Abschluss-Anhängsel: "Soll ich ...?", "Lass mich wissen ...", ungefragter Ausblick/nächste Schritte.
+- Ungefragte Optionen, Alternativen, Empfehlungen, Trade-off-Exkurse.
+- Hedging: keine abgesicherten Rundum-Varianten. Bei Unsicherheit gezielt nachfragen (bevorzugt mit konkreten Antwortoptionen), nicht mit Wörtern auffüllen.
+
+STRUKTUR:
+- Antwort/Ergebnis zuerst. Herleitung und Begründung nur auf ausdrückliche Nachfrage.
+- Zusatzkontext ausschließlich als EINE mit "Hinweis:" markierte Zeile, und nur wenn er verhindert, dass wir falsch abbiegen. Kein Absatz.
+- Belegen statt ausbreiten: datei:zeile statt Zitat/Nacherzählung.
+
+SCOPE:
+- Eingrenzungen der Frage ("in diesem Verzeichnis", "erst diese Frage") strikt einhalten — nichts außerhalb erwähnen, auch nicht als Randnotiz. Als Constraint für Werkzeugaufrufe übernehmen (z. B. Pfad-Argument), nicht die Ausgabe nachträglich filtern.
+
+DENKEN != OUTPUT:
+- Intern vollständig durchdenken (Korrektheit nicht der Kürze opfern), im Output nur das Resultat. Kürze gilt für die Antwort, nicht für die Analyse.
+
+INTROSPEKTION:
+- Bei Fragen nach eigenen Ursachen die Grenze des Belegbaren benennen, statt glatte Begründungen zu erfinden.
+
+KALIBRIERUNG (so sieht eine gute Antwort aus):
+  Frage: "Greift der Hook?"
+  Gut:   "Ja. Kommt als system-reminder an, deshalb im Chat unsichtbar für dich."
+  Schlecht: "Das ist eine gute Frage! Lass uns das prüfen. Grundsätzlich werden Hooks ... [5 Sätze Herleitung] ... Zusammenfassend: ja, er greift. Soll ich die Konfiguration zeigen?"

hooks/inject-answer-rules.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+# UserPromptSubmit-Hook: Injiziert die Antwort-Checkliste in den Kontext,
+# damit die Prägnanz-Regeln im Moment der Generierung präsent sind.
+# stdout wird bei UserPromptSubmit dem Modell-Kontext hinzugefügt.
+
+set -euo pipefail
+
+CHECKLIST="$(dirname "$(readlink -f "$0")")/antwort-checkliste.txt"
+[[ -f "$CHECKLIST" ]] || exit 0
+
+echo "Vor dem Antworten gegen diese Regeln prüfen:"
+cat "$CHECKLIST"
+
+exit 0

hooks/pre-bash-checks.sh

@@ -22,8 +22,10 @@ extract_subject() {
   fi
 }
 
-# Git-Commit-Pruefungen
+# Git-Commit-Pruefungen (uebersprungen bei SSH-gewrappten Befehlen: die committen
-if echo "$cmd" | grep -qE '^\s*git\s+commit\b'; then
+# auf einem Remote-Repo, dessen Branch lokal nicht ermittelbar ist - Fehlalarm der
+# main-Pruefung; der Remote-Host hat eigene Guards)
+if echo "$cmd" | grep -qE '^\s*git\s+commit\b' && ! echo "$cmd" | grep -qE '^\s*ssh\b'; then
   # Branch-Schutz: kein direkter Commit auf main (sofern kein Opt-out per Markerdatei)
   branch=$(git rev-parse --abbrev-ref HEAD 2>/dev/null || echo "")
   repo_root=$(git rev-parse --show-toplevel 2>/dev/null || echo "")

skills/openscad/README.md

@@ -0,0 +1,278 @@
+# OpenSCAD Claude Code Skill
+
+A Claude Code skill for programmatic 3D CAD using [OpenSCAD](https://openscad.org/). Design, preview, iterate, reconstruct from STL, and export 3D-printable models — with AI-driven visual feedback and automated mesh comparison.
+
+## Features
+
+- **Programmatic 3D modeling** — Generate `.scad` files from natural language descriptions
+- **AI vision feedback loop** — Render multi-angle PNG previews and analyze them to iteratively refine designs
+- **STL-to-SCAD reconstruction** — Reverse-engineer STL meshes into parametric OpenSCAD code using SVG profiling and SDF optimization
+- **Image-to-CAD replication** — Reproduce physical objects from reference photos
+- **Parametric design** — All dimensions as variables, overridable via CLI `-D` flags
+- **Mesh comparison** — Boolean diff rendering and IoU scoring to verify reconstruction accuracy
+- **Printability analysis** — Wall thickness, overhang, and manifold validation
+- **Reusable module library** — Common 3D printing patterns (counterbores, heat-set bosses, ribs, snap-fits)
+- **Eval framework** — Automated testing with 20 binary assertions across 4 scenarios (100% pass rate)
+
+## Prerequisites
+
+- **OpenSCAD** installed and accessible via CLI
+  ```bash
+  brew install openscad    # macOS
+  ```
+- **Python packages** (for STL reconstruction):
+  ```bash
+  pip3 install trimesh numpy scipy rtree shapely
+  ```
+- **admesh** (for mesh validation):
+  ```bash
+  brew install admesh
+  ```
+- **Claude Code** CLI installed
+
+## Installation
+
+### Option 1: Clone and symlink (recommended)
+
+```bash
+git clone https://github.com/andreahaku/openscad_claude_skill.git ~/Development/Claude/openscad_claude_skill
+
+mkdir -p ~/.claude/skills
+ln -sf ~/Development/Claude/openscad_claude_skill ~/.claude/skills/openscad
+```
+
+### Option 2: Direct clone into skills
+
+```bash
+git clone https://github.com/andreahaku/openscad_claude_skill.git ~/.claude/skills/openscad
+```
+
+### Verify installation
+
+```bash
+openscad --version
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh quick ~/.claude/skills/openscad/templates/bracket.scad
+```
+
+## Usage
+
+The skill triggers automatically when you mention 3D modeling, CAD, STL export, or OpenSCAD:
+
+```
+/openscad design a phone stand with adjustable angle
+```
+
+### Modes
+
+| Mode | Trigger | Description |
+|------|---------|-------------|
+| **Design** | "design a bracket", "make a box" | Create new 3D models from descriptions |
+| **Replicate** | "reproduce this from the photo" | Reverse-engineer objects from reference images |
+| **Reconstruct** | "convert this STL to SCAD" | Reverse-engineer STL meshes into parametric code |
+| **Refine** | "make it taller", "add fillets" | Iterate on existing designs |
+| **Export** | "export STL", "ready for printing" | Generate production files |
+| **Analyze** | "check printability" | Validate designs for 3D printing |
+
+### Example Workflows
+
+**Design from scratch:**
+```
+> Design a parametric enclosure for a Raspberry Pi 4 with ventilation slots
+```
+
+**Reconstruct from STL:**
+```
+> Convert /path/to/model.stl into parametric OpenSCAD code
+```
+
+**Export with parameter overrides:**
+```
+> Export the bracket with width=100 and wall=3
+```
+
+## Project Structure
+
+```
+openscad_claude_skill/
+├── SKILL.md                              # Skill definition (6 modes, 762 lines)
+├── README.md                             # This file
+├── scripts/
+│   ├── openscad-render.sh                # Core render/export/preview engine (7 commands)
+│   ├── openscad-project.sh               # Project scaffolding (init/list/clean/info)
+│   ├── openscad-validate.sh              # Strict validation with error categorization
+│   ├── openscad-stl-analyze.sh           # STL mesh analysis (bbox, cross-sections, gaps)
+│   ├── openscad-stl-reconstruct.sh       # Automated reconstruction pipeline (SVG profiling)
+│   ├── openscad-stl-compare.sh           # Mesh comparison (boolean diff, accuracy %)
+│   └── openscad-sdf-optimize.py          # SDF parameter optimizer (IoU scoring)
+├── references/
+│   ├── language-reference.md             # Complete OpenSCAD v2021.01 cheat sheet
+│   └── reconstruction-guide.md           # Best practices for STL-to-SCAD reconstruction
+├── templates/
+│   ├── enclosure.scad                    # Parametric electronics box with lid
+│   ├── bracket.scad                      # L-bracket with countersunk holes
+│   └── printable-lib.scad               # Reusable 3D printing modules
+└── eval/
+    ├── eval.json                         # 4 test scenarios, 20 binary assertions
+    └── results.jsonl                     # Test results log
+```
+
+## Scripts
+
+### `openscad-render.sh` — Core Rendering Engine
+
+```bash
+bash scripts/openscad-render.sh quick <file.scad>           # Single isometric preview
+bash scripts/openscad-render.sh preview <file.scad>          # 4-view (iso, front, right, top)
+bash scripts/openscad-render.sh stl <file.scad> [-D ...]     # Export STL
+bash scripts/openscad-render.sh 3mf <file.scad>              # Export 3MF
+bash scripts/openscad-render.sh export <file.scad>           # Full export (STL + 3MF + PNG)
+bash scripts/openscad-render.sh analyze <file.scad>          # Printability analysis
+bash scripts/openscad-render.sh custom <file.scad> [opts]    # Custom render
+```
+
+### `openscad-stl-reconstruct.sh` — Automated STL Analysis
+
+```bash
+bash scripts/openscad-stl-reconstruct.sh model.stl output_dir/
+```
+
+Runs the full analysis pipeline:
+1. **trimesh** mesh analysis (volume, watertight, normals, bounding cylinder)
+2. **SVG profiling** via OpenSCAD `projection(cut=true)` at 5 Z levels
+3. **Primitive detection** (RANSAC axis estimation, normal-based CSG inference)
+
+Output: `mesh-info.json`, `primitives.json`, SVG slice files
+
+### `openscad-stl-compare.sh` — Mesh Comparison
+
+```bash
+bash scripts/openscad-stl-compare.sh original.stl reconstruction.stl output_dir/
+```
+
+Produces:
+- **diff-A-minus-B.png** — Geometry in original but MISSING from reconstruction
+- **diff-B-minus-A.png** — EXTRA geometry in reconstruction
+- **overlay.png** — Both models overlaid
+- **Geometric accuracy %** — Based on volume of boolean differences
+
+### `openscad-sdf-optimize.py` — Parameter Optimizer
+
+```bash
+python3 scripts/openscad-sdf-optimize.py model.stl stadium-slot --verbose
+```
+
+Uses Signed Distance Fields + IoU scoring to find optimal parameters without invoking OpenSCAD in the loop. Converges in seconds via `scipy.optimize.minimize`.
+
+### `openscad-stl-analyze.sh` — Raw Mesh Analysis
+
+```bash
+bash scripts/openscad-stl-analyze.sh model.stl                          # Full analysis
+bash scripts/openscad-stl-analyze.sh model.stl --cross-section z 5.0     # Slice at Z=5
+bash scripts/openscad-stl-analyze.sh model.stl --gaps y                  # Find Y-axis gaps
+```
+
+## STL-to-SCAD Reconstruction
+
+The reconstruction pipeline converts triangle meshes into clean, parametric OpenSCAD code:
+
+### The Sculptor Approach
+
+All reconstructions follow the sculptor method — start from a solid block, subtract everything:
+
+```openscad
+difference() {
+    solid_body();        // 1. Full solid first
+    channels();          // 2. Subtract channels/slots
+    taper_cuts();        // 3. Subtract wedges
+    all_holes();         // 4. ALL holes LAST
+}
+```
+
+### Two-Tier Pipeline
+
+1. **SVG Profile Analysis** (fast) — `openscad-stl-reconstruct.sh` identifies the model topology by slicing at multiple Z levels
+2. **SDF Optimization** (precise) — `openscad-sdf-optimize.py` finds exact parameters via IoU scoring
+
+### Proven Results
+
+| Model | Complexity | Accuracy | Iterations |
+|-------|-----------|----------|------------|
+| Toothpaste Squeezer | Simple (1180 tri) | 96.27% | 2 |
+| Interior Bracket | Complex (7576 tri) | 95.63% | 8 |
+
+See `references/reconstruction-guide.md` for the complete best practices guide.
+
+## Templates
+
+### `printable-lib.scad` — Reusable Modules
+
+```openscad
+use <printable-lib.scad>
+
+shell_box(outer=[60,40,20], wall=2, floor=2);
+rounded_box([50,30,10], r=3);
+screw_clearance_hole(d=3, h=10, fit="close");
+counterbore_hole(shaft_d=3, head_d=6, head_h=3, h=12);
+countersink_hole(d=3, cs_d=6, cs_h=2, h=10);
+heatset_boss(insert_d=4.6, insert_h=5, wall=2, h=8);
+screw_post(outer_d=7, inner_d=3, h=10);
+rib(len=20, height=12, thick=2);
+snap_tab(width=8, length=6, thick=1.5, overhang=0.8);
+text_label("Hello", size=8, depth=1);
+
+fit_clearance("press");   // 0.15mm
+fit_clearance("close");   // 0.25mm
+fit_clearance("slide");   // 0.30mm
+fit_clearance("loose");   // 0.40mm
+```
+
+## 3D Printing Guidelines
+
+- **Wall thickness**: min 1.2mm (FDM with 0.4mm nozzle)
+- **Clearance**: 0.2-0.3mm for fitting parts
+- **Overhangs**: < 45° from vertical; prefer chamfers on downward faces
+- **Epsilon** (`eps = 0.01`) in all boolean operations
+- **Flat bottoms** for bed adhesion
+- **`assert()`** for self-validating parametric models
+- **Counterbore vs countersink**: always check reference images
+
+## Environment Variables
+
+| Variable | Default | Description |
+|----------|---------|-------------|
+| `OPENSCAD_BIN` | `$(command -v openscad)` | Path to OpenSCAD binary |
+| `OPENSCAD_IMGSIZE` | `800,600` | Default preview image size |
+| `OPENSCAD_COLORSCHEME` | `DeepOcean` | Default color scheme |
+
+## Eval Framework
+
+The skill includes automated testing:
+
+```bash
+ls eval/
+# eval.json      — 4 test scenarios, 20 binary assertions
+# results.jsonl  — Test results log
+```
+
+**Baseline: 100% pass rate (20/20)** across:
+- Design (simple box + sculptor approach)
+- STL reconstruction (96.27% geometric accuracy)
+- Parametric export with -D overrides
+
+## Contributing
+
+1. Fork the repository
+2. Create a feature branch
+3. Make changes
+4. Run: `bash scripts/openscad-render.sh quick templates/bracket.scad`
+5. Submit a pull request
+
+## License
+
+MIT
+
+## Credits
+
+Built with Claude Code (Anthropic), with architectural input from Gemini (Google) and Codex (OpenAI).
+
+Powered by [OpenSCAD](https://openscad.org/) — The Programmers Solid 3D CAD Modeller.

skills/openscad/SKILL.md

@@ -0,0 +1,917 @@
+---
+disable-model-invocation: true
+name: openscad
+description: >
+  Programmatic 3D CAD with OpenSCAD. Generate .scad files, render STL for 3D printing,
+  preview as PNG with AI vision feedback. Triggers on: 3D model, STL, 3D print, parametric
+  design, openscad, CAD, enclosure, bracket, or any 3D modeling task.
+argument-hint: "<description of object to design or path to existing .scad file>"
+allowed-tools: "Bash(*),Read,Edit,Write,Glob,Grep,Agent"
+metadata:
+  version: 1.0.0
+  category: 3d-cad
+  tags: [openscad, 3d-printing, cad, parametric, stl, modeling, design]
+---
+
+# OpenSCAD Skill
+
+Design, render, preview, and export 3D models using OpenSCAD's programmatic CAD engine. Supports iterative AI-driven design refinement via rendered PNG analysis.
+
+## Environment
+
+- **OpenSCAD binary**: `/opt/homebrew/bin/openscad` (v2021.01)
+- **Working directory for designs**: `~/openscad-projects/` (create per-project subdirectories)
+- **Skill scripts**: `~/.claude/skills/openscad/scripts/`
+- **Templates**: `~/.claude/skills/openscad/templates/`
+- **Language reference**: `~/.claude/skills/openscad/references/`
+
+## Modes
+
+The skill operates in six modes, auto-detected from the user's request:
+
+- **Design** — Create a new 3D model from a description
+- **Replicate** — Reproduce a physical object from reference images
+- **Reconstruct** — Reverse-engineer an STL mesh into parametric OpenSCAD code
+- **Refine** — Iterate on an existing .scad file (modify, preview, repeat)
+- **Export** — Render final STL/3MF for 3D printing
+- **Analyze** — Review an existing design for printability or improvements
+
+---
+
+## Workflow: Design Mode
+
+When the user asks to create a new 3D object:
+
+### Step 1: Understand Requirements
+
+Clarify with the user:
+- **What** is the object? (enclosure, bracket, gear, container, etc.)
+- **Dimensions** — key measurements in mm
+- **Purpose** — functional print, aesthetic, mechanical fit?
+- **Constraints** — printer bed size, material, wall thickness preferences
+- **Parametric?** — which dimensions should be adjustable?
+
+### Step 2: Set Up Project
+
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-project.sh init "<project-name>"
+```
+
+This creates `~/openscad-projects/<project-name>/` with subdirectories for source, output, and previews.
+
+### Step 3: Generate the .scad File
+
+Write the OpenSCAD code to `~/openscad-projects/<project-name>/src/main.scad`.
+
+**Mandatory file structure (Feature Tree pattern):**
+```openscad
+// 1. PARAMETERS (independent variables)
+width = 60;  height = 30;  wall = 2;
+
+// 2. DERIVED DIMENSIONS (calculated from parameters)
+inner_width = width - 2 * wall;
+
+// 3. BASE PROFILE (2D sketch — the core shape)
+module sketch_base() {
+    offset(r = corner_r)
+        square([width - 2*corner_r, depth - 2*corner_r], center=true);
+}
+
+// 4. PRIMARY BODY (extrude the sketch)
+module body() { linear_extrude(height = height) sketch_base(); }
+
+// 5. ADDITIVE FEATURES (bosses, ribs, tabs)
+module features_add() { ... }
+
+// 6. SUBTRACTIVE FEATURES (holes, slots, pockets — ALWAYS LAST)
+module features_cut() { ... }
+
+// 7. ASSEMBLY (the Feature Tree)
+difference() {
+    union() { body(); features_add(); }
+    features_cut();
+}
+```
+
+**Profile-first design rules:**
+- Prefer `polygon()` + `linear_extrude()` over `hull()` of 3D primitives
+- Use `offset(r=radius)` for corner rounding instead of `hull()` with cylinders
+- Use `rotate_extrude()` for axially symmetric parts (never stack cylinders)
+- Define dimensions relative to edges/features, not absolute coordinates: `hole_x = total_length - edge_margin` (not magic numbers)
+- Cascade tolerances from a single `fit_clearance` parameter
+
+**Critical rules for generating OpenSCAD code:**
+- Read `~/.claude/skills/openscad/references/language-reference.md` if unsure about syntax
+- Always define parametric dimensions as variables at the top of the file
+- Use `$fn = 64;` for smooth curves (or higher for final renders)
+- Add comments explaining each section
+- Use modules for reusable parts
+- Keep wall thickness >= 1.2mm for FDM printing
+- Design with the print orientation in mind (flat bottom, minimal overhangs)
+
+### Step 4: Preview
+
+Render a multi-angle PNG preview:
+
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh preview ~/openscad-projects/<project-name>/src/main.scad
+```
+
+This generates 4 preview images (front, side, top, isometric) in the project's `previews/` directory.
+
+### Step 5: Analyze Preview
+
+Read each preview PNG using the Read tool to see the rendered object. Evaluate:
+- Does the shape match the user's description?
+- Are proportions correct?
+- Are there visible artifacts or unintended geometry?
+- Would this print well? (overhangs, bridging, thin walls)
+
+Report findings to the user with the preview images.
+
+### Step 6: Iterate
+
+If changes are needed, edit the .scad file and re-render. Repeat Steps 4-5 until the user is satisfied. Each iteration should be targeted — change one aspect at a time.
+
+### Step 7: Export
+
+When the design is approved:
+
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh export ~/openscad-projects/<project-name>/src/main.scad
+```
+
+This produces:
+- `output/model.stl` — for slicing and printing
+- `output/model.3mf` — alternative format (better metadata)
+- `previews/final-preview.png` — high-res final render
+
+---
+
+## Workflow: Replicate Mode
+
+When the user provides reference images of a physical object to reproduce in OpenSCAD:
+
+### Step 1: Analyze Reference Images
+
+Read ALL provided reference images using the Read tool. For each image, extract:
+- **Overall shape**: What geometric primitives compose this object?
+- **Proportions**: Relative dimensions (height-to-width ratio, etc.)
+- **Features**: Holes, fillets, chamfers, textures, slots, lips, threads
+- **Symmetry**: Is it symmetric along any axis?
+- **Construction**: How would you decompose it into boolean operations?
+
+If dimensions are provided, note them. If not, estimate proportions from the images and ask the user for at least one known measurement to establish scale.
+
+### Step 2: Create Decomposition Plan
+
+Before writing any code, describe the object as a series of OpenSCAD operations:
+
+```
+Object: Phone stand
+Decomposition:
+1. Base: flat rectangle with rounded corners (80x60x5mm)
+2. Back support: angled plate (60x3mm, tilted 70 degrees)
+3. Front lip: small ridge to hold phone (60x3x8mm)
+4. Fillet: smooth transition between base and back support
+5. Cable channel: cylinder subtracted from base center
+```
+
+Present this plan to the user for confirmation before coding.
+
+### Step 3: Generate Initial .scad File
+
+Write the OpenSCAD code based on the decomposition. Set up the project:
+
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-project.sh init "<object-name>"
+```
+
+Write the .scad to the project's `src/main.scad`.
+
+### Step 4: Render and Compare
+
+Generate a preview from the **same angle** as the reference image:
+
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh quick ~/openscad-projects/<name>/src/main.scad
+```
+
+Read both the reference image and the rendered preview. Compare them side by side mentally:
+- Does the overall silhouette match?
+- Are proportions correct?
+- Are features (holes, edges, curves) in the right places?
+- What's the biggest discrepancy?
+
+### Step 5: Iterative Refinement Loop
+
+For each discrepancy found:
+1. Identify which part of the .scad code controls the mismatched feature
+2. Make a **single targeted edit** to improve the match
+3. Re-render from the same angle
+4. Re-compare with the reference
+
+**Refinement priorities** (fix in this order):
+1. Overall shape and proportions
+2. Major features (holes, cutouts, protrusions)
+3. Angles and curves
+4. Fillets, chamfers, and surface details
+5. Fine details
+
+### Step 6: Multi-Angle Validation
+
+Once the primary angle looks good, render from all angles that have reference images:
+
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh preview ~/openscad-projects/<name>/src/main.scad
+```
+
+Compare each rendered view against its corresponding reference image. Fix any angle-specific discrepancies.
+
+### Step 7: Dimensional Verification
+
+If the user provided measurements, add `echo()` statements to verify:
+
+```openscad
+echo("Total width:", width);
+echo("Total height:", height);
+echo("Wall thickness:", wall);
+```
+
+Render with echo capture to verify dimensions match specifications.
+
+### Step 8: Export
+
+When the user confirms the replication is satisfactory, export for printing.
+
+### Tips for Accurate Replication
+
+- **Start simple**: Begin with bounding-box primitives, then refine
+- **Use reference dimensions**: If user says "it's about 10cm tall", anchor ALL proportions to that
+- **Match camera angle**: Use `--camera` to match the reference photo's perspective
+- **Organic shapes**: Approximate with hull(), minkowski(), or rotate_extrude() of a profile
+- **Iterate small**: Change one thing per render cycle
+- **Ask when unsure**: If a feature is ambiguous from the images, ask the user rather than guessing
+
+---
+
+## Workflow: Reconstruct Mode (STL-to-SCAD)
+
+When the user provides an STL file and wants it converted to parametric OpenSCAD code:
+
+### Overview
+
+STL files are triangle meshes with no semantic information about the original primitives or operations that created them. Reconstruction is the process of analyzing the mesh geometry and re-expressing it as clean, parametric OpenSCAD code. This is valuable because:
+- Parametric code can be modified (change dimensions, add features)
+- OpenSCAD code is human-readable and version-controllable
+- The resulting model can be adapted to different use cases
+
+### Critical Rules for Reconstruction
+
+**Read `references/reconstruction-guide.md` before starting any reconstruction.** It contains the complete best practices guide learned from real reconstructions.
+
+**Rule 1: SCULPTOR APPROACH (mandatory).** Start from a full solid block, subtract ALL features. Never build up from pieces — CSG ordering bugs cause added material to cover previously-cut holes. Structure: `difference() { solid_body(); channels(); tapers(); ALL_holes_LAST(); }`
+
+**Rule 2: NEVER add features based on assumptions.** Always verify with SVG contour data AND reference images. If a feature doesn't appear as a separate contour in the SVG slices, IT DOES NOT EXIST. Known hallucinations to avoid:
+- Pyramids/cones from render shadows
+- Cylinders from curved wall edges
+- Top holes from through-hole exit points
+
+**Rule 3: Bounding box match ≠ correct model.** 0.000mm bbox delta can mean only 70% geometric accuracy. Always use mesh comparison (`openscad-stl-compare.sh`) with boolean diff images.
+
+**Rule 4: ANALYZE FIRST, DECOMPOSE, THEN CHOOSE per-component approach.**
+Do NOT jump to code. The analysis phase must answer these questions:
+1. **What are the dominant features?** (diagonal arm, clips, channels, holes)
+2. **What is the thinnest axis?** That's the likely extrusion direction — NOT necessarily the stability score winner
+3. **Can the object be decomposed into simpler sub-objects?** Model each with its best technique
+4. **Where are internal channels/gaps?** Slice along Z to find multi-body cross-sections
+
+**Rule 5: Choose the extrusion axis by geometry, not just stability score.**
+
+The profile extractor's stability score finds the axis with the most uniform cross-section. But this is misleading for models with diagonal features — slicing along Z for a diagonal bracket produces staircase artifacts. Instead:
+
+| Model Type | Best Extrusion Axis | Why |
+|-----------|-------------------|-----|
+| Flat bracket/plate | Thinnest axis (smallest extent) | Profile in the wide plane captures all detail |
+| Diagonal/angled arm | Thinnest axis | Diagonals live in the plane of the two longest axes |
+| Clean extrusion (stability < 0.1) | Stability-score axis | Profiles are identical → stability is reliable |
+| Cylindrical (stability > 0.3) | Object's rotational axis | Use rotate_extrude or parametric primitives |
+| Truly complex (no good axis) | Dense multi-axis slabbing | 2mm slabs along thinnest axis |
+
+```bash
+# Always run ALL analysis tools before writing any code:
+bash ~/.claude/skills/openscad/scripts/openscad-stl-reconstruct.sh model.stl analysis/
+python3 ~/.claude/skills/openscad/scripts/openscad-profile-extract.py model.stl --json analysis/profile.json
+python3 ~/.claude/skills/openscad/scripts/openscad-adaptive-slice.py model.stl analysis/
+```
+
+After analysis, compare: **thinnest axis extent** vs **stability-score axis**. If they differ, the thinnest axis is usually better for models with angled features.
+
+**Rule 6: Choose the right technique for each component:**
+
+| Geometry | Best Approach | Expected Accuracy |
+|----------|--------------|-------------------|
+| Flat/angular (brackets, plates) | Profile extraction + linear_extrude | 90-96% |
+| Diagonal features (angled arms, tapers) | Profile along thinnest axis + linear_extrude | 85-92% |
+| Simple known shapes (stadium, box) | Parametric primitives + SDF optimizer | 90-96% |
+| Cylindrical features (puzzle tabs, bosses) | Parametric circle() + square() | 85-95% |
+| Smooth transitions (convex shapes only) | hull() between boundary profiles | 85-90% |
+| Multi-width models (width varies along axis) | Dense X-slab (2mm profiles along thinnest axis) | ~92% |
+| Mixed (curves + flats) | Polygon profile (hi-res, tol=0.02) | 70-80% |
+| Complex organic shapes | import() original STL + parametric modifications | N/A |
+
+**Rule 7: hull() ONLY for convex profiles.** Hull between two profiles creates the convex hull — it fills in ALL concavities (channels, clips, U-forks, hooks). Only use hull for simple solid zones with 1 contour and no holes. For concave profiles, use linear_extrude of a representative profile instead.
+
+**Rule 8: Dense X-slab approach for complex models.**
+When no single extrusion works, slice every 2mm along the thinnest axis:
+1. At each X position, extract the full Y-Z cross-section (ALL bodies, not just the largest)
+2. Extrude each slab for 2mm width
+3. Union all slabs — gaps between bodies are naturally preserved
+4. Note: this approach has a ~6% volume overestimate floor from polygon extraction artifacts. Below 6% requires hand-modeled parametric geometry.
+
+**Use the automated reconstruction analysis FIRST — before writing any code:**
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-stl-reconstruct.sh model.stl output_dir/
+```
+
+This runs the full pipeline: mesh stats (trimesh), 2D profile slices (OpenSCAD projection), primitive detection (RANSAC/normal analysis), and generates SVG profiles at multiple Z levels. The SVG profile analysis is the MOST IMPORTANT output — it reveals the complete cross-section structure at each height level.
+
+**The SVG Profile Method** (preferred over vertex analysis):
+1. `projection(cut=true)` slices the STL at a Z height → exports 2D SVG
+2. Parse the SVG to count contours: BODY (large area) vs HOLES (small area)
+3. Compare contours at different Z levels to understand how the shape changes with height
+4. This reveals: channels, slots, holes, wall thickness, taper angles — all from 2D data
+
+**After analysis, verify with mesh comparison:**
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-stl-compare.sh original.stl reconstruction.stl output_dir/
+```
+Target: >95% geometric accuracy. Use diff images to identify remaining discrepancies.
+
+### Step 1: Automated Analysis (run ALL tools)
+
+```bash
+# Tool 1: SVG profiling + primitive detection
+bash ~/.claude/skills/openscad/scripts/openscad-stl-reconstruct.sh model.stl analysis/
+
+# Tool 2: Profile extraction + extrusion axis detection
+python3 ~/.claude/skills/openscad/scripts/openscad-profile-extract.py model.stl \
+    --output analysis/profile.scad --json analysis/profile.json
+
+# Tool 3: Adaptive multi-axis feature map
+python3 ~/.claude/skills/openscad/scripts/openscad-adaptive-slice.py model.stl analysis/
+```
+
+**Key outputs to examine:**
+- `analysis/slices/*.svg` — 2D profiles at 5 Z levels
+- `analysis/profile.json` — extrusion axis, stability score, profile points, hole count
+- `analysis/adaptive-slicing.json` — feature zones on all 3 axes, transition locations
+- `analysis/primitives.json` — detected cylinders/planes
+- `analysis/mesh-info.json` — volume, dimensions, symmetry
+
+### Step 1b: Understand the Object (BEFORE writing code)
+
+After running analysis tools, render multi-angle previews and answer:
+
+1. **What are the main components?** (e.g. "bottom clip + diagonal arm + top clip")
+2. **Which axis is thinnest?** Compare extents — the thinnest is likely the extrusion direction
+3. **Are there diagonal/angled features?** If yes, the stability-score axis is probably WRONG
+4. **Where do cross-sections change?** Check the adaptive slicer's transition zones
+5. **Are there multi-body zones?** (channels, rails, gaps between parts)
+
+**Decision tree — axis selection:**
+1. If `stability_score < 0.1` AND thinnest axis matches stability axis → clean extrusion, use `profile.scad`
+2. If model has **diagonal features** → use the **thinnest axis** regardless of stability score
+3. If `stability_score < 0.3` AND no diagonals → stability axis + feature variations
+4. If `stability_score > 0.3` → complex shape. Try dense X-slab along thinnest axis, or decompose into sub-objects
+
+**Decision tree — technique per component:**
+- Simple extruded body → profile + linear_extrude along extrusion axis
+- Diagonal arm/strut → profile along thinnest axis captures it naturally
+- Clips, hooks, U-channels → profile extraction (NOT hull — hull fills concavities)
+- Cylindrical features → parametric circle() + square(), NOT polygon profiles
+- Smooth convex transitions → hull() between boundary profiles (ONLY if convex)
+- Complex multi-width → dense 2mm slabs along thinnest axis
+
+**For models with cylindrical features** (stability > 0.3 or SVG shows circular contours):
+- Do NOT rely on polygon profiles — they approximate curves poorly
+- Identify circle centers and radii from the SVG contour data
+- Model with `circle()` + `square()` in 2D, then extrude
+
+Then render multi-angle previews:
+
+```openscad
+// Temporary viewer file
+import("path/to/model.stl");
+```
+
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh preview /tmp/stl-viewer.scad
+```
+
+Read all preview images to understand the 3D shape from multiple angles.
+
+### Step 1b: Auto-Reconstruction (NEW — recommended for most models)
+
+After running the adaptive slicer, use the auto-reconstructor to generate parametric .scad directly:
+
+```bash
+# Option A: With pre-computed analysis
+python3 ~/.claude/skills/openscad/scripts/openscad-auto-reconstruct.py model.stl \
+    --analysis analysis/ --output project/src/main.scad
+
+# Option B: Run analysis + reconstruction in one step
+python3 ~/.claude/skills/openscad/scripts/openscad-auto-reconstruct.py model.stl \
+    --output project/src/main.scad --run-analysis
+
+# Option C: Tighter circle fitting for precision parts
+python3 ~/.claude/skills/openscad/scripts/openscad-auto-reconstruct.py model.stl \
+    --analysis analysis/ --output project/src/main.scad --circle-threshold 0.3
+```
+
+This automatically:
+1. Parses the feature map JSON into zones
+2. Extracts profiles at zone boundaries
+3. Fits circles/arcs to replace polygon approximations (Feature 3)
+4. Generates hull() blends for transition zones (Feature 2)
+5. Emits one OpenSCAD module per zone with sculptor assembly (Feature 1)
+
+The output is a good starting point — review and refine the generated .scad, then verify with mesh comparison. For models with cylindrical features, this typically achieves >85% accuracy automatically (vs 75% with polygon-only).
+
+### Step 2: Detailed Structure Mapping
+
+**For simple models** (5 SVG slices are enough):
+Parse the SVG contours to count bodies vs holes at each Z level.
+
+**For complex models** (brackets, enclosures with multiple features):
+Use the adaptive multi-axis slicer for efficient feature detection:
+```bash
+python3 ~/.claude/skills/openscad/scripts/openscad-adaptive-slice.py model.stl analysis/
+```
+This automatically: scans all 3 axes with coarse pass (5mm) → detects transitions → fine pass (0.5mm) around transitions. Produces a feature map classifying each zone as `solid`, `shell_or_channel`, `multi_body`, or `complex`.
+
+For manual fine-grained slicing at specific heights:
+```bash
+for z in $(seq 0.5 1 <max_z>); do
+    echo "projection(cut=true) translate([0,0,-$z]) import(\"model.stl\");" > /tmp/s.scad
+    openscad -o "slices/z${z}.svg" /tmp/s.scad
+done
+```
+
+Parse each SVG to build a structural map:
+```
+Z=0-5:   1 body (full width) + 8 holes     → Solid base with screw holes
+Z=5-10:  2 bodies + 8 holes                → Channel appeared, walls split
+Z=10-20: 2 bodies narrowing                → Taper zone (measure rate)
+Z=20-33: 2 bodies constant width           → Top section
+Z=25-27: Bodies interrupted                → Counterbore pockets at this depth
+```
+
+**Hole positions from SVG centroids** — for each hole contour at a given Z, compute the centroid. This gives exact X,Y positions far more reliably than vertex analysis.
+
+**Feature verification rule:** If a feature doesn't appear as a distinct contour in the SVG data, IT DOES NOT EXIST in the model. Never add features based on visual interpretation of 3D renders alone.
+
+### Step 3: Choose Approach and Decompose
+
+Based on the analysis data, choose the reconstruction approach:
+
+**Approach A — Profile Extrusion** (for extruded parts, stability < 0.3):
+```bash
+# The profile extractor already generated the .scad — use it as a starting point
+cat analysis/profile.scad
+# Adjust: add cavity with offset(delta=-wall), add floor, add features
+```
+
+**Approach B — Parametric Primitives** (for known shapes or cylindrical features):
+Create a decomposition plan using measured dimensions from SVG data:
+```
+Decomposition:
+1. Base: square([80, 80]) + circle tabs — from SVG outer contour at Z=mid
+2. Cavity: offset(delta=-wall) of base — from SVG inner contour
+3. Floor: solid at Z=0 to floor_h — from SVG at Z=0 (1 contour = solid)
+4. Holes: cylinder(d=3) at SVG hole centroids
+5. Counterbores: cylinder(d=8, h=2) at same positions
+```
+
+**Approach C — Hybrid** (for complex shapes with both flat and curved features):
+1. Extract polygon profile for the overall outline
+2. Identify which curves in the profile are circles (regular spacing, arc-like)
+3. Replace those polygon sections with parametric `circle(r)` operations
+4. Assemble: `square() + circle()` union for tabs, `difference()` for slots
+
+**Counterbore vs Countersink** — always verify from reference images:
+- **Counterbore**: flat cylindrical pocket (`cylinder(d=cb_d, h=cb_depth)`)
+- **Countersink**: conical taper (`cylinder(d1=cs_d, d2=hole_d, h=cs_depth)`)
+- Most 3D-printed parts use counterbores, not countersinks
+
+### Step 4: Write Parametric .scad Code
+
+Create a new project and write the reconstructed code:
+
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-project.sh init "<name>-reconstructed"
+```
+
+**Key principles for reconstruction:**
+- Extract ALL dimensions as named variables at the top
+- Use meaningful variable names that describe the physical feature
+- Add comments linking each section to the original STL features
+- Include `echo()` statements for bounding box verification
+- Add `assert()` for parameter ranges
+
+### Step 5: Visual Comparison Loop
+
+Render the reconstructed .scad and compare side-by-side with the original STL renders:
+
+1. Render the reconstruction from the same camera angles as Step 1
+2. Read both sets of images
+3. Compare silhouettes, proportions, and feature placement
+4. Identify the biggest discrepancy
+5. Fix it and re-render
+6. Repeat until the reconstruction matches the original
+
+### Step 6: Overlay Verification
+
+For precise verification, create an overlay .scad file:
+
+```openscad
+// Overlay: original STL (transparent) vs reconstruction
+%import("path/to/original.stl");  // % = transparent background
+color("red", 0.6) reconstructed_model();
+```
+
+Render this overlay — any RED areas visible through the transparent original indicate reconstruction errors. Any grey areas not covered by red indicate missing geometry.
+
+### Step 7: Mesh-to-Mesh Comparison
+
+**This is the most important verification step.** Export the reconstruction as STL and compare it against the original using boolean difference:
+
+```bash
+# Export reconstruction
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh stl ~/openscad-projects/<name>/src/main.scad
+
+# Run mesh comparison
+bash ~/.claude/skills/openscad/scripts/openscad-stl-compare.sh \
+    path/to/original.stl \
+    ~/openscad-projects/<name>/output/main.stl \
+    ~/openscad-projects/<name>/previews/comparison
+```
+
+This produces:
+- **diff-A-minus-B.png** — geometry in original but MISSING from reconstruction (what you need to add)
+- **diff-B-minus-A.png** — EXTRA geometry in reconstruction not in original (what you need to remove)
+- **overlay.png** — both models overlaid for visual check
+- **Geometric accuracy %** — based on volume of boolean differences vs original volume
+
+**Target: >95% geometric accuracy.** If below 95%, examine the diff images to identify which features are wrong, fix them, re-export, and re-compare. Iterate until accuracy is satisfactory.
+
+**Important:** Bounding box delta can be 0.000mm while geometric accuracy is only 78% — internal features matter more than outer dimensions.
+
+### Step 8: Dimensional Verification
+
+Compare echo output from the reconstruction with the STL bounding box:
+
+```openscad
+echo(str("Reconstructed BBOX: ", width, " x ", depth, " x ", height));
+```
+
+### Step 9: SDF Parameter Optimization (Advanced)
+
+If the SVG profile method doesn't achieve >95% accuracy, use the SDF optimizer for automatic parameter tuning:
+
+```bash
+python3 ~/.claude/skills/openscad/scripts/openscad-sdf-optimize.py \
+    path/to/original.stl \
+    stadium-slot \
+    --verbose \
+    --output analysis/sdf-result.json
+```
+
+This works by:
+1. Sampling 30,000 random points in the bounding box
+2. Computing target occupancy (inside/outside original mesh) via trimesh
+3. Defining the reconstruction as a parametric SDF (Signed Distance Field)
+4. Using `scipy.optimize.minimize(method="Powell")` to maximize IoU (Intersection over Union)
+5. Generating OpenSCAD code with optimized parameters
+
+**When to use**: When you know the correct model topology (e.g., "stadium body with cylindrical slot") but can't find the exact parameters. The optimizer finds them automatically.
+
+**Supported model types**: `stadium-slot`, `box-holes`. Add new types by defining an SDF function in the script.
+
+**Workflow**: Run `openscad-stl-reconstruct.sh` first (to identify the model topology), then `openscad-sdf-optimize.py` (to find exact parameters), then `openscad-stl-compare.sh` (to verify).
+
+**Prerequisites**: `pip3 install trimesh numpy scipy rtree`
+
+### Common Pitfalls
+
+- **Bounding box match ≠ correct model.** A model with completely wrong internal geometry can still have a 0.000mm bounding box delta. Always verify visually from multiple angles.
+- **Don't assume features from renders alone.** What looks like a cylinder in a top-down view might just be a curved wall edge. Always verify with vertex analysis.
+- **Coincident faces cause Z-fighting.** If a feature touches the body boundary exactly, use `intersection()` to clip it cleanly rather than making it the exact same size.
+- **Don't flip between adding and removing features.** If unsure whether a feature exists, run cross-section analysis before deciding. Oscillating between "add bar" and "remove bar" wastes iterations.
+- **Offset features are common.** Cylinders, holes, and channels are often NOT centered. Always calculate the actual center from vertex data rather than assuming symmetry.
+
+### Limitations
+
+- **Organic shapes** (sculpted, freeform surfaces) cannot be fully reconstructed as primitives. For these, keep the STL import and wrap it in a module.
+- **Very complex models** (1000+ features) should be reconstructed incrementally, starting with the major body and adding features one group at a time.
+- **Thread geometry** in STL is extremely difficult to reconstruct. Use `threads.scad` library instead of trying to match individual thread faces.
+- **Text/engravings** embedded in STL meshes are very hard to extract. It's better to re-add text using OpenSCAD's `text()` module.
+
+### Hybrid Approach
+
+For complex models, use a hybrid strategy:
+```openscad
+// Import the complex organic base from STL
+module original_base() {
+    import("base-section.stl");
+}
+
+// Reconstruct and parameterize the mechanical features
+module mounting_bracket(width=30, hole_d=5) {
+    difference() {
+        original_base();
+        // Add parametric mounting holes
+        for (pos = hole_positions)
+            translate(pos) cylinder(d=hole_d, h=50, center=true);
+    }
+}
+```
+
+This lets the user modify the parametric parts while keeping the complex geometry intact.
+
+---
+
+## Workflow: Refine Mode
+
+When the user wants to modify an existing design:
+
+### Step 1: Read the Existing File
+
+```bash
+# Find .scad files in the project
+```
+Read the .scad source to understand the current design.
+
+### Step 2: Render Current State
+
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh preview /path/to/file.scad
+```
+
+Read the preview images to see what currently exists.
+
+### Step 3: Apply Changes
+
+Edit the .scad file with the requested modifications. Use the Edit tool for surgical changes.
+
+### Step 4: Re-render and Compare
+
+Generate new previews and visually compare with the previous version. Report what changed.
+
+### Step 5: Repeat or Export
+
+Continue iterating or export when satisfied.
+
+---
+
+## Workflow: Export Mode
+
+Quick export of an existing .scad file:
+
+```bash
+# Single format
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh stl /path/to/file.scad
+
+# Multiple formats
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh export /path/to/file.scad
+
+# With parameter overrides
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh stl /path/to/file.scad -D 'width=50' -D 'height=30'
+```
+
+---
+
+## Workflow: Analyze Mode
+
+Review a design for printability:
+
+```bash
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh analyze /path/to/file.scad
+```
+
+This renders cross-section views and reports:
+- Object bounding box dimensions
+- Whether the mesh is manifold (watertight)
+- Estimated print time indicators (volume, surface area from STL)
+- Visual check of overhangs via bottom-up view
+
+---
+
+## Script Reference
+
+All scripts live in `~/.claude/skills/openscad/scripts/`:
+
+| Script | Purpose |
+|--------|---------|
+| `openscad-render.sh` | Core render/export/preview engine |
+| `openscad-project.sh` | Project scaffolding and management |
+| `openscad-validate.sh` | Strict validation with categorized error output |
+| `openscad-stl-analyze.sh` | STL mesh analysis: bbox, cross-sections, gap detection |
+| `openscad-stl-compare.sh` | Mesh comparison: boolean diff, volume delta, accuracy % |
+| `openscad-stl-reconstruct.sh` | Automated STL analysis: profiles, primitives, CSG inference |
+| `openscad-sdf-optimize.py` | SDF-based parameter optimizer (IoU scoring, no OpenSCAD in loop) |
+| `openscad-adaptive-slice.py` | Adaptive multi-axis slicing (coarse→transitions→fine on X,Y,Z) |
+| `openscad-auto-reconstruct.py` | Auto-translate feature map → parametric .scad (circle fitting, hull blending) |
+
+### openscad-render.sh Commands
+
+```bash
+# Quick single preview (isometric)
+openscad-render.sh quick <file.scad>
+
+# Multi-angle preview (4 views)
+openscad-render.sh preview <file.scad>
+
+# Export STL only
+openscad-render.sh stl <file.scad> [-D 'var=val' ...]
+
+# Export all formats (STL + 3MF + PNG)
+openscad-render.sh export <file.scad> [-D 'var=val' ...]
+
+# Analyze printability
+openscad-render.sh analyze <file.scad>
+
+# Custom render
+openscad-render.sh custom <file.scad> --format png --imgsize 1920,1080 --camera 0,0,0,45,0,30,200
+```
+
+### openscad-project.sh Commands
+
+```bash
+# Initialize new project
+openscad-project.sh init <project-name>
+
+# List projects
+openscad-project.sh list
+
+# Clean build artifacts
+openscad-project.sh clean <project-name>
+```
+
+---
+
+## OpenSCAD Code Guidelines
+
+### File Structure Convention
+
+```openscad
+// ============================================
+// Project: <name>
+// Description: <what this models>
+// Author: Claude Code + User
+// ============================================
+
+// --- Parameters (user-configurable) ---
+width = 50;        // [mm] overall width
+height = 30;       // [mm] overall height
+depth = 20;        // [mm] overall depth
+wall = 2.0;        // [mm] wall thickness
+tolerance = 0.3;   // [mm] printer tolerance
+
+// --- Rendering quality ---
+$fn = 64;          // curve smoothness (use 128+ for final export)
+eps = 0.01;        // epsilon for clean boolean operations
+
+// --- Derived dimensions ---
+inner_width = width - 2 * wall;
+inner_height = height - 2 * wall;
+
+// --- Main model ---
+main_assembly();
+
+// --- Modules ---
+module main_assembly() {
+    // ...
+}
+```
+
+### 3D Printing Best Practices in OpenSCAD
+
+- **Wall thickness**: minimum 1.2mm for FDM (2-3 perimeters with 0.4mm nozzle)
+- **Tolerance**: 0.2-0.3mm clearance for fitting parts together (peg-in-hole, snap fits)
+- **Overhangs**: keep below 45 degrees from vertical, or add supports in design
+- **Chamfer vs fillet**: prefer chamfers on downward-facing surfaces (avoids supports); use fillets on top surfaces
+- **Bridging**: max ~10mm unsupported spans
+- **First layer**: design flat bottoms for bed adhesion; largest flat surface on build plate
+- **Epsilon constant**: always define `eps = 0.01;` and use it in boolean operations to prevent Z-fighting / coplanar faces
+- **Manifold geometry**: always ensure boolean operations produce valid solids; operands must overlap
+- **Resolution**: use `$fn = 64` for preview, `$fn = 128` for export
+- **Design intent**: Define hole positions relative to edges (`hole_x = length - margin`), never as absolute coordinates
+- **Tolerance chains**: Define a single `fit_clearance` parameter and derive all clearances from it
+- **Assert validation**: Use `assert()` to validate parameters: `assert(wall >= 1.2)`, `assert(boss_d > hole_d + 2*wall)`
+- **Profile-first**: Use `offset(r=corner_r)` on 2D `polygon()` instead of `hull()` with 3D cylinders
+
+### Common Patterns
+
+**Rounded box:**
+```openscad
+module rounded_box(size, radius) {
+    minkowski() {
+        cube([size.x - 2*radius, size.y - 2*radius, size.z - radius]);
+        cylinder(r=radius, h=radius);
+    }
+}
+```
+
+**Shell (hollow object):**
+```openscad
+module shell(outer_size, wall) {
+    difference() {
+        cube(outer_size);
+        translate([wall, wall, wall])
+            cube([outer_size.x - 2*wall, outer_size.y - 2*wall, outer_size.z]);
+    }
+}
+```
+
+**Screw hole with countersink:**
+```openscad
+module screw_hole(d=3, h=10, cs_d=6, cs_h=2) {
+    union() {
+        cylinder(d=d, h=h);
+        translate([0, 0, h - cs_h])
+            cylinder(d1=d, d2=cs_d, h=cs_h);
+    }
+}
+```
+
+---
+
+## Available Libraries
+
+Popular libraries that can be installed for advanced features:
+
+| Library | Use Case | Install |
+|---------|----------|---------|
+| **BOSL2** | Swiss-army knife: attachments, shapes, threading, paths | `git clone https://github.com/BelfrySCAD/BOSL2 ~/.local/share/OpenSCAD/libraries/BOSL2` |
+| **NopSCADlib** | Vitamins (screws, nuts, electronics, bearings) | `git clone https://github.com/nophead/NopSCADlib ~/.local/share/OpenSCAD/libraries/NopSCADlib` |
+| **threads.scad** | Metric threads, hex bolts, nuts | `git clone https://github.com/rcolyer/threads-scad ~/.local/share/OpenSCAD/libraries/threads` |
+| **Round-Anything** | Smooth fillets and rounding | `git clone https://github.com/Irev-Dev/Round-Anything ~/.local/share/OpenSCAD/libraries/Round-Anything` |
+| **YAPP_Box** | Parametric project enclosures | `git clone https://github.com/mrWheel/YAPP_Box ~/.local/share/OpenSCAD/libraries/YAPP_Box` |
+| **Catch'n'Hole** | Nut catches, screw holes | `git clone https://github.com/mmalecki/catchnhole ~/.local/share/OpenSCAD/libraries/catchnhole` |
+
+Check installed libraries:
+```bash
+ls ~/.local/share/OpenSCAD/libraries/ 2>/dev/null
+ls /opt/homebrew/share/openscad/libraries/ 2>/dev/null
+```
+
+When user needs a library, install it and add `use <library/file.scad>` to the .scad source.
+
+---
+
+## Error Handling
+
+When OpenSCAD fails:
+
+1. **Parse errors** — `ERROR: Parser error: syntax error in file X, line Y`
+   - Read the .scad file at the reported line
+   - Fix syntax (common: missing semicolons, unmatched braces/parens, wrong function names)
+   - Re-render
+
+2. **Geometry errors** — `WARNING: Object may not be a valid 2-manifold`
+   - Check boolean operations aren't creating degenerate geometry
+   - Ensure shapes overlap properly for difference/intersection
+   - Add small epsilon offsets (0.01mm) to prevent coplanar faces
+
+3. **Rendering timeouts** — complex models with high `$fn`
+   - Lower `$fn` for preview (32), raise for export (128)
+   - Simplify geometry where possible
+   - Use `render()` to cache intermediate results
+
+4. **Empty output** — model produces no geometry
+   - Check that modules are actually called
+   - Verify boolean operations don't subtract everything
+   - Use `echo()` statements to debug variable values
+
+Always capture stderr when rendering — it contains warnings and errors:
+```bash
+openscad -o output.stl input.scad 2>&1
+```
+
+---
+
+## Camera Presets for Multi-View
+
+| View | Camera Parameters |
+|------|-------------------|
+| Front | `--camera 0,0,0,90,0,0,<dist>` |
+| Back | `--camera 0,0,0,90,0,180,<dist>` |
+| Right | `--camera 0,0,0,90,0,90,<dist>` |
+| Left | `--camera 0,0,0,90,0,270,<dist>` |
+| Top | `--camera 0,0,0,0,0,0,<dist>` |
+| Bottom | `--camera 0,0,0,180,0,0,<dist>` |
+| Isometric | `--autocenter --viewall` (default) |
+| 3/4 view | `--camera 0,0,0,55,0,25,<dist>` |
+
+Use `--autocenter --viewall` to auto-calculate distance, or specify explicit distance for consistent framing across iterations.

skills/openscad/references/language-reference.md

@@ -0,0 +1,188 @@
+# OpenSCAD Language Reference (v2021.01)
+
+## Syntax & Declaration
+```openscad
+var = value;                              // variable assignment
+var = cond ? value_if_true : value_if_false;  // ternary
+var = function (x) x + x;                // function literal
+module name(params) { ... }              // module definition
+function name(params) = expr;            // function definition
+include <file.scad>                       // include (executes top-level code)
+use <file.scad>                           // import (only modules/functions)
+```
+
+## Constants
+- `undef` — undefined value
+- `PI` — 3.14159...
+
+## Special Variables
+| Variable | Purpose |
+|----------|---------|
+| `$fn` | Fixed number of segments for circles/spheres |
+| `$fa` | Minimum angle per segment |
+| `$fs` | Minimum segment size |
+| `$t` | Animation step (0–1) |
+| `$vpr` | Viewport rotation |
+| `$vpt` | Viewport translation |
+| `$vpd` | Viewport distance |
+| `$vpf` | Viewport field of view |
+| `$children` | Number of child modules |
+| `$preview` | `true` in preview (F5), `false` in render (F6) |
+
+## Modifier Characters
+- `*` — disable (don't render)
+- `!` — show only this
+- `#` — highlight/debug (transparent red)
+- `%` — transparent/background
+
+## 3D Primitives
+```openscad
+cube(size, center=false)                   // cube([w,d,h]) or cube(s)
+sphere(r=radius)                           // sphere(d=diameter)
+cylinder(h, r=radius, center=false)        // cylinder(h, d=diameter)
+cylinder(h, r1, r2, center=false)          // cone/tapered cylinder
+polyhedron(points, faces, convexity)        // custom solid
+```
+
+## 2D Primitives
+```openscad
+circle(r=radius)                           // circle(d=diameter)
+square(size, center=false)                 // square([w,h])
+polygon(points, paths)                      // 2D polygon
+text(t, size=10, font, halign, valign, spacing)  // text string
+```
+
+## 2D → 3D Extrusion
+```openscad
+linear_extrude(height, center, twist, slices, scale)
+    circle(10);                            // extrude 2D to 3D
+
+rotate_extrude(angle=360, convexity)
+    translate([20,0]) circle(5);           // lathe/revolve
+
+surface(file="heightmap.dat", center)       // heightmap to 3D
+```
+
+## Transformations
+```openscad
+translate([x, y, z])                       // move
+rotate([x, y, z])                          // rotate (degrees)
+rotate(angle, [x, y, z])                   // rotate around axis
+scale([x, y, z])                           // scale
+resize([x, y, z], auto)                    // resize to exact dimensions
+mirror([x, y, z])                          // mirror across plane
+multmatrix(m)                              // 4x4 matrix transform
+color("name", alpha)                       // color("red"), color("#ff0000")
+color([r, g, b, a])                        // color by RGBA (0-1)
+offset(r=radius)                           // 2D offset (round)
+offset(delta=dist, chamfer=false)          // 2D offset (sharp)
+```
+
+## Boolean Operations
+```openscad
+union() { a(); b(); }                      // combine (A + B)
+difference() { a(); b(); }                // subtract (A - B)
+intersection() { a(); b(); }              // overlap only (A ∩ B)
+```
+
+## Advanced Operations
+```openscad
+hull() { a(); b(); }                       // convex hull
+minkowski() { a(); b(); }                 // Minkowski sum (slow!)
+render(convexity) { ... }                  // force CGAL render (cache)
+projection(cut=false) { ... }             // 3D → 2D projection
+```
+
+## Import / Export
+```openscad
+import("file.stl")                         // import STL, OFF, AMF, 3MF
+import("file.dxf")                         // import 2D DXF
+import("file.svg")                         // import 2D SVG
+```
+
+## Flow Control
+```openscad
+if (condition) { ... } else { ... }
+for (i = [0:10]) { ... }                  // range [start:end]
+for (i = [0:2:10]) { ... }                // range [start:step:end]
+for (i = [1, 5, 7]) { ... }               // list iteration
+for (i = [...], j = [...]) { ... }         // nested loops
+intersection_for(i = [...]) { ... }        // intersection across iterations
+let (a = expr) { ... }                     // local variable scope
+```
+
+## List Comprehensions
+```openscad
+list = [ for (i = [0:10]) i * 2 ];                    // generate
+list = [ for (i = [0:10]) if (i % 2 == 0) i ];        // filter
+list = [ for (i = [0:10]) let (x = i*i) x ];           // with let
+list = [ each sublist ];                                // flatten
+```
+
+## Math Functions
+| Function | Description |
+|----------|-------------|
+| `abs(x)` | Absolute value |
+| `sign(x)` | Sign (-1, 0, 1) |
+| `sin(x)`, `cos(x)`, `tan(x)` | Trig (degrees) |
+| `asin(x)`, `acos(x)`, `atan(x)` | Inverse trig |
+| `atan2(y, x)` | Two-argument arctangent |
+| `floor(x)`, `ceil(x)`, `round(x)` | Rounding |
+| `ln(x)`, `log(x)` | Natural / base-10 log |
+| `pow(base, exp)` | Power |
+| `sqrt(x)` | Square root |
+| `exp(x)` | e^x |
+| `min(a,b,...)`, `max(a,b,...)` | Min/max |
+| `norm(v)` | Vector magnitude |
+| `cross(v1, v2)` | Cross product |
+| `rands(min, max, count)` | Random numbers |
+| `len(x)` | Length of list/string |
+
+## String Functions
+| Function | Description |
+|----------|-------------|
+| `str(...)` | Concatenate to string |
+| `chr(code)` | ASCII code → character |
+| `ord(char)` | Character → ASCII code |
+| `search(needle, haystack)` | Search in list/string |
+
+## Type Testing
+```openscad
+is_undef(x)   is_bool(x)    is_num(x)
+is_string(x)  is_list(x)    is_function(x)
+```
+
+## Other Functions
+```openscad
+echo("msg", var)                           // debug output
+assert(condition, "message")               // assertion
+concat(list1, list2)                       // concatenate lists
+lookup(key, [[k,v], ...])                  // table lookup
+children(idx)                              // access child N of module
+parent_module(idx)                         // access parent module name
+version()                                  // OpenSCAD version string
+```
+
+## Operators
+| Type | Operators |
+|------|-----------|
+| Arithmetic | `+` `-` `*` `/` `%` `^` |
+| Relational | `<` `<=` `==` `!=` `>=` `>` |
+| Logical | `&&` `\|\|` `!` |
+| Indexing | `list[i]` `list.x` `list.y` `list.z` |
+
+## Tips for AI-Generated Code
+- **Always set `$fn`** for predictable circle resolution
+- **Use `center=true`** when building symmetric objects with difference()
+- **Add 0.01mm epsilon** to boolean cuts to avoid coplanar Z-fighting:
+  ```openscad
+  difference() {
+      cube([10, 10, 10]);
+      translate([-0.01, 2, 2])
+          cube([10.02, 6, 6]);  // slightly larger to ensure clean cut
+  }
+  ```
+- **Modules for reuse**: parameterize everything, compose with modules
+- **Comments**: explain the "why", dimensions in mm
+- **Print orientation**: think about which face goes on the build plate
+- **Manifold check**: all boolean operands must overlap; no coincident faces

skills/openscad/references/reconstruction-guide.md

@@ -0,0 +1,241 @@
+# STL-to-SCAD Reconstruction Best Practices
+
+## Profile-Based Reconstruction (Preferred Method)
+
+For extruded parts (brackets, plates, channels), extract the 2D profile directly from the mesh and convert it to OpenSCAD `polygon()` + `linear_extrude()`. This is more accurate than fitting known primitives.
+
+### Step 1: Detect Extrusion Axis
+Use trimesh to find the axis with the most stable cross-section:
+- Slice the mesh along X, Y, and Z at 64 levels each
+- For each axis, measure stability: std(area), std(perimeter), std(hole_count)
+- The axis with lowest stability score is the extrusion axis
+
+### Step 2: Extract the Dominant Profile
+- Find the slice with the largest area (the representative cross-section)
+- Simplify the polygon (remove micro-vertices from tessellation)
+- Handle holes: inner contours become `paths` in OpenSCAD `polygon()`
+
+### Step 3: Convert to OpenSCAD
+```openscad
+// Auto-generated from mesh profile extraction
+linear_extrude(height = <extrusion_length>)
+    polygon(
+        points = [<extracted_points>],
+        paths = [<outer_boundary>, <hole_1>, <hole_2>]
+    );
+```
+
+### Step 4: Add Secondary Features
+Features that vary along the extrusion axis (holes, counterbores) are detected by comparing slice profiles at different heights. Where a slice has more holes than the dominant profile, subtract cylinders.
+
+## The Sculptor Approach (MANDATORY)
+
+Always model as a sculptor: start from a solid block, then subtract material.
+
+```openscad
+// CORRECT: sculptor approach
+difference() {
+    solid_body();       // 1. Full solid block first
+    channel();          // 2. Subtract channels/slots
+    taper_cuts();       // 3. Subtract wedges/tapers
+    all_holes();        // 4. Subtract ALL holes LAST
+}
+
+// WRONG: additive approach (holes get covered)
+union() {
+    difference() {
+        base();
+        some_holes();   // These get covered by wings!
+    }
+    left_wing();        // Covers the holes above
+    right_wing();
+}
+```
+
+**Why**: In OpenSCAD, `difference()` only applies to its immediate children. If you add material (wings) after cutting holes, the new material covers the holes. The sculptor approach ensures ALL cuts happen after ALL additions.
+
+## Analysis Pipeline
+
+### Step 1: Automated SVG Profile Analysis
+```bash
+bash openscad-stl-reconstruct.sh model.stl output_dir/
+```
+This gives you the 30,000-foot view: dimensions, volume, symmetry, primitive hints.
+
+### Step 2: Detailed 1mm Z-Slicing
+For complex models, slice at every 1mm (not just 5 levels):
+```bash
+# Generate slices at every Z level
+for z in $(seq 0.5 1 <max_z>); do
+    echo "projection(cut=true) translate([0,0,-$z]) import(\"model.stl\");" > /tmp/s.scad
+    openscad -o "slices/z${z}.svg" /tmp/s.scad
+done
+```
+Parse each SVG to extract:
+- Number of contours (1 body = solid level, 2+ = channels/features)
+- Contour sizes: BODY (>500mm²), FEATURE (50-500mm²), HOLE (<50mm²)
+- Hole positions from contour centroids
+- How width changes with Z (reveals taper rate)
+
+### Step 3: Identify Structure from Profile Data
+```
+Z=0-5:   1 body (full width)           → Solid base
+Z=5-10:  2 bodies + 8 holes            → Channel appeared, base holes
+Z=10-20: 2 bodies narrowing            → Taper zone (measure rate)
+Z=20-33: 2 bodies (constant width)     → Top section
+Z=25-27: bodies interrupted by holes   → Upper counterbore holes
+```
+
+### Step 4: Write OpenSCAD (Sculptor Method)
+1. Create the FULL solid body (base + wings as one block)
+2. Subtract the channel
+3. Subtract taper wedges (use `hull()` for linear tapers)
+4. Subtract ALL holes in separate modules, called LAST
+
+### Step 5: Compare and Iterate
+```bash
+bash openscad-stl-compare.sh original.stl reconstruction.stl output/
+```
+- Check accuracy % (target: >95%)
+- Read diff images to identify WHAT is wrong
+- Fix ONE thing per iteration
+- Re-compare
+
+## Hole Patterns
+
+### Counterbore (flat cylindrical pocket)
+Most common in 3D-printed brackets. A shallow cylinder + through hole:
+```openscad
+module counterbore(hole_d, cb_d, cb_depth, total_h) {
+    cylinder(d=hole_d, h=total_h);    // Through hole
+    cylinder(d=cb_d, h=cb_depth);     // Flat pocket
+}
+```
+
+### Countersink (conical taper)
+Less common in 3D prints, used for flat-head screws:
+```openscad
+module countersink(hole_d, cs_d, cs_depth, total_h) {
+    cylinder(d=hole_d, h=total_h);
+    cylinder(d1=cs_d, d2=hole_d, h=cs_depth);
+}
+```
+
+**Always check reference images** to determine which type is used. Don't assume.
+
+### Hole Orientation Patterns
+Complex brackets often have holes on multiple faces:
+- **Bottom face**: Vertical (Z-axis) holes
+- **Angled faces**: Holes perpendicular to the face (rotate by taper angle)
+- **Side walls**: Horizontal (Y-axis) holes
+- **Each set may have different spacing and count**
+
+Extract hole positions from SVG centroids at the appropriate Z level.
+
+## Taper/Wedge Subtraction
+
+For a 45° taper that narrows a wing from full width to reduced width:
+```openscad
+// Wedge: 0 thickness at bottom, full thickness at top
+hull() {
+    translate([0, outer_edge, z_start])
+        cube([length, eps, z_end - z_start]);    // Thin edge
+    translate([0, outer_edge, z_end - eps])
+        cube([length, taper_amount, eps]);         // Full face
+}
+// Then remove the rectangular block above the taper
+translate([0, outer_edge, z_end])
+    cube([length, taper_amount, z_top - z_end]);
+```
+
+## Common Pitfalls
+
+1. **CSG order**: ALWAYS cut holes after building the full solid
+2. **Feature hallucination**: Don't add features you can't verify in the reference
+3. **Conical vs cylindrical**: Check if countersinks are tapered or flat
+4. **Symmetric assumptions**: Don't assume symmetry — verify from SVG data
+5. **Volume match ≠ shape match**: A model can have correct volume but wrong shape
+6. **SVG Y-axis is inverted**: OpenSCAD projection flips Y coordinates
+
+## Dependencies
+
+```bash
+pip3 install trimesh numpy scipy rtree shapely
+brew install admesh
+```
+
+## Accuracy Targets
+
+| Level | Accuracy | When to stop |
+|-------|----------|-------------|
+| Draft | >85% | Initial structure verification |
+| Good  | >95% | Functional part, ready for test print |
+| Excellent | >98% | Production quality |
+
+The 95% threshold is achievable for most mechanical parts in 4-6 iterations using the SVG profiling approach. The remaining 5% is typically tessellation differences and minor feature details.
+
+## When to Use Polygon Profiles vs Parametric Primitives
+
+### Use extracted polygon profiles when:
+- The shape has mostly flat/angular surfaces (brackets, plates, channels)
+- The curves are gentle and well-approximated by ~200 polygon points
+- Speed is more important than last-5% accuracy
+- Expected accuracy: 75-96% depending on curve complexity
+
+### Use parametric primitives (circle, cylinder) when:
+- The shape has prominent cylindrical features (puzzle tabs, screw holes, bosses)
+- The shape can be decomposed into known primitives (square + circles)
+- You need >95% accuracy on curved surfaces
+- The model has symmetry that can be exploited
+
+### Hybrid approach (best for complex models):
+1. Extract the polygon profile for the overall outline
+2. Identify which curves are circles/arcs from the profile data
+3. Replace polygon approximations with parametric `circle(r)` where possible
+4. Use `offset(r)` for rounded corners instead of polygon vertices
+
+### Key lesson: polygon simplification tolerance matters enormously
+- 0.3mm tolerance → ~50 points → curves become flat → 52% accuracy
+- 0.05mm tolerance → ~150 points → curves approximate → 75% accuracy
+- 0.02mm tolerance → ~230 points → curves close but not perfect → 75% accuracy
+- Diminishing returns beyond ~200 points for polygon-based approaches
+- For >90% on cylindrical surfaces, parametric primitives are required
+
+## Feature Hallucination Prevention
+
+NEVER add features based on visual interpretation of renders alone.
+- The toothpaste squeezer "cylinder" was actually a rounded slot floor
+- The puzzle tray "pyramid" didn't exist at all — it was a shadow in the render
+- ALWAYS verify features with SVG slice data (contour count, area, holes)
+- If a feature doesn't show as a separate contour in the SVG slices, IT DOESN'T EXIST
+
+## Adaptive Multi-Axis Slicing
+
+The `openscad-adaptive-slice.py` script scans STL on all 3 axes:
+1. Coarse pass (5mm) → detects where cross-section changes
+2. Fine pass (0.5mm) only at transition zones
+3. Classifies each zone: solid, shell_or_channel, multi_body, complex
+
+### How to interpret the feature map
+
+**Zone types and their OpenSCAD equivalents:**
+- `solid` (1 contour, 0 holes) → `linear_extrude()` of the profile
+- `shell_or_channel` (2 contours) → walls around a cavity, use `offset(delta=-wall)`
+- `solid_with_holes` (1 contour, N holes) → solid body with `difference()` holes
+- `multi_body` (N contours) → multiple separate parts or holes
+- `complex` → may need `hull()` between profiles or `polyhedron()`
+
+**Detecting specific features from zone evolution:**
+- **Chamfer/taper**: contour width decreases progressively across slices
+- **Fillet**: smooth curvature in contour centroids between zones
+- **Counterbore**: nested circular contours with constant radius for several slices
+- **Through-hole**: hole contour appears in ALL slices along that axis
+- **Blind hole**: hole contour appears then disappears
+
+**Generating OpenSCAD from zones:**
+- Stable zones (many identical slices) → `linear_extrude(height=zone_length)` of representative profile
+- Transition zones (gradual change) → `hull()` between two profiles at zone boundaries
+- Feature zones (holes, counterbores) → `difference()` with fitted cylinders
+
+### Future: Feature Map → OpenSCAD Translator
+The next evolution is automatic translation: parse the JSON feature map, emit one `module zone_N()` per zone, assemble with `difference()/union()` in the correct order. This would close the loop from STL → analysis → parametric .scad automatically.

skills/openscad/scripts/openscad-adaptive-slice.py

@@ -0,0 +1,320 @@
+#!/usr/bin/env python3
+"""
+openscad-adaptive-slice.py — Adaptive multi-axis SVG slicing
+
+Slices an STL on all 3 axes with adaptive resolution:
+1. Coarse pass (every 5mm) → detect transitions
+2. Fine pass (every 0.5mm) only at transitions
+3. Outputs a complete feature map of the model
+
+Usage:
+    python3 openscad-adaptive-slice.py <file.stl> <output_dir> [--coarse 5] [--fine 0.5]
+"""
+
+import numpy as np
+import trimesh
+from trimesh import intersections
+from shapely.geometry import MultiLineString
+from shapely.ops import polygonize, unary_union
+import json
+import sys
+import os
+import argparse
+
+
+def segments_to_polygons(segments, snap=1e-4):
+    """Convert mesh slice segments to Shapely polygons."""
+    lines = []
+    for seg in np.asarray(segments):
+        a = tuple(np.round(seg[0] / snap) * snap)
+        b = tuple(np.round(seg[1] / snap) * snap)
+        if a != b:
+            lines.append([a, b])
+    if not lines:
+        return []
+    return [p for p in polygonize(MultiLineString(lines)) if p.area > snap * snap]
+
+
+def slice_at_height(mesh, axis, height):
+    """Slice mesh at a given height along an axis. Returns polygon descriptors."""
+    try:
+        normal = np.zeros(3)
+        normal[axis] = 1.0
+        origin = np.zeros(3)
+        origin[axis] = height
+
+        segments, _, _ = intersections.mesh_multiplane(
+            mesh, plane_origin=origin, plane_normal=normal, heights=[0.0])
+
+        if not segments or len(segments[0]) == 0:
+            return None
+
+        polys = segments_to_polygons(segments[0])
+        if not polys:
+            return None
+
+        combined = unary_union(polys)
+        n_holes = sum(len(p.interiors) for p in polys) if hasattr(polys[0], 'interiors') else 0
+
+        return {
+            'height': round(float(height), 3),
+            'area': round(float(combined.area), 2),
+            'perimeter': round(float(combined.length), 2),
+            'n_contours': len(polys),
+            'n_holes': n_holes,
+            'bounds': [round(float(x), 2) for x in combined.bounds],
+            'width': round(float(combined.bounds[2] - combined.bounds[0]), 2),
+            'height_2d': round(float(combined.bounds[3] - combined.bounds[1]), 2),
+        }
+    except Exception:
+        return None
+
+
+def detect_transitions(slices, threshold=0.1):
+    """Find heights where the cross-section changes significantly."""
+    transitions = []
+    for i in range(1, len(slices)):
+        prev = slices[i - 1]
+        curr = slices[i]
+        if prev is None or curr is None:
+            if prev is not None or curr is not None:
+                transitions.append(i)
+            continue
+
+        # Detect changes in area, contour count, or holes
+        area_change = abs(curr['area'] - prev['area']) / max(prev['area'], 1)
+        contour_change = curr['n_contours'] != prev['n_contours']
+        hole_change = curr['n_holes'] != prev['n_holes']
+        width_change = abs(curr['width'] - prev['width']) / max(prev['width'], 1)
+
+        if area_change > threshold or contour_change or hole_change or width_change > threshold:
+            transitions.append(i)
+
+    return transitions
+
+
+def adaptive_slice_axis(mesh, axis, coarse_step=5.0, fine_step=0.5, fine_range=3.0, threshold=0.1):
+    """Adaptive slicing along one axis.
+
+    1. Coarse pass at coarse_step intervals
+    2. Detect transitions
+    3. Fine pass around each transition
+    """
+    axis_names = ['X', 'Y', 'Z']
+    lo, hi = mesh.bounds[0][axis], mesh.bounds[1][axis]
+    extent = hi - lo
+
+    # Pass 1: Coarse
+    coarse_heights = np.arange(lo + coarse_step / 2, hi, coarse_step)
+    coarse_slices = []
+    for h in coarse_heights:
+        s = slice_at_height(mesh, axis, h)
+        coarse_slices.append(s)
+
+    # Detect transitions
+    trans_indices = detect_transitions(coarse_slices, threshold)
+    transition_heights = [float(coarse_heights[i]) for i in trans_indices]
+
+    print(f"  {axis_names[axis]}: {len(coarse_heights)} coarse slices, "
+          f"{len(transition_heights)} transitions detected")
+
+    if transition_heights:
+        zones = ", ".join(f"{h:.1f}" for h in transition_heights)
+        print(f"    Transition zones: {zones}")
+
+    # Pass 2: Fine slicing around transitions
+    fine_slices = []
+    fine_heights_set = set()
+    for th in transition_heights:
+        fine_lo = max(lo, th - fine_range)
+        fine_hi = min(hi, th + fine_range)
+        for h in np.arange(fine_lo, fine_hi, fine_step):
+            h_round = round(float(h), 3)
+            if h_round not in fine_heights_set:
+                fine_heights_set.add(h_round)
+                s = slice_at_height(mesh, axis, h_round)
+                if s:
+                    fine_slices.append(s)
+
+    # Combine coarse + fine, sorted by height
+    all_slices = []
+    all_heights = set()
+
+    for s, h in zip(coarse_slices, coarse_heights):
+        h_round = round(float(h), 3)
+        if s and h_round not in all_heights:
+            all_heights.add(h_round)
+            all_slices.append(s)
+
+    for s in fine_slices:
+        if s['height'] not in all_heights:
+            all_heights.add(s['height'])
+            all_slices.append(s)
+
+    all_slices.sort(key=lambda s: s['height'])
+
+    print(f"    Total slices: {len(all_slices)} ({len(coarse_slices)} coarse + {len(fine_slices)} fine)")
+
+    return {
+        'axis': axis_names[axis],
+        'extent': round(float(extent), 3),
+        'n_coarse': len(coarse_slices),
+        'n_fine': len(fine_slices),
+        'n_total': len(all_slices),
+        'transitions': [round(h, 3) for h in transition_heights],
+        'slices': all_slices,
+    }
+
+
+def build_feature_map(axis_results):
+    """Build a unified feature map from all 3 axes."""
+    features = []
+
+    for result in axis_results:
+        axis = result['axis']
+        slices = result['slices']
+        transitions = result['transitions']
+
+        if not slices:
+            continue
+
+        # Identify feature zones (between transitions)
+        zones = []
+        sorted_trans = sorted(transitions)
+
+        # Zone before first transition
+        pre_slices = [s for s in slices if s['height'] < (sorted_trans[0] if sorted_trans else 1e6)]
+        if pre_slices:
+            avg_area = np.mean([s['area'] for s in pre_slices])
+            avg_contours = round(np.mean([s['n_contours'] for s in pre_slices]))
+            avg_holes = round(np.mean([s['n_holes'] for s in pre_slices]))
+            zones.append({
+                'axis': axis,
+                'from': round(float(slices[0]['height']), 2),
+                'to': round(float(sorted_trans[0]), 2) if sorted_trans else round(float(slices[-1]['height']), 2),
+                'avg_area': round(float(avg_area), 1),
+                'contours': int(avg_contours),
+                'holes': int(avg_holes),
+                'type': classify_zone(avg_area, avg_contours, avg_holes),
+            })
+
+        # Zones between transitions
+        for i in range(len(sorted_trans)):
+            t_lo = sorted_trans[i]
+            t_hi = sorted_trans[i + 1] if i + 1 < len(sorted_trans) else slices[-1]['height']
+            zone_slices = [s for s in slices if t_lo <= s['height'] <= t_hi]
+            if zone_slices:
+                avg_area = np.mean([s['area'] for s in zone_slices])
+                avg_contours = round(np.mean([s['n_contours'] for s in zone_slices]))
+                avg_holes = round(np.mean([s['n_holes'] for s in zone_slices]))
+                zones.append({
+                    'axis': axis,
+                    'from': round(float(t_lo), 2),
+                    'to': round(float(t_hi), 2),
+                    'avg_area': round(float(avg_area), 1),
+                    'contours': int(avg_contours),
+                    'holes': int(avg_holes),
+                    'type': classify_zone(avg_area, avg_contours, avg_holes),
+                })
+
+        features.extend(zones)
+
+    return features
+
+
+def classify_zone(area, contours, holes):
+    """Classify a zone based on its cross-section properties."""
+    if contours == 1 and holes == 0:
+        return 'solid'
+    elif contours == 1 and holes > 0:
+        return 'solid_with_holes'
+    elif contours == 2 and holes == 0:
+        return 'shell_or_channel'
+    elif contours > 2:
+        return 'multi_body'
+    else:
+        return 'complex'
+
+
+def main():
+    parser = argparse.ArgumentParser(description='Adaptive multi-axis STL slicing')
+    parser.add_argument('stl_file', help='Input STL file')
+    parser.add_argument('output_dir', help='Output directory')
+    parser.add_argument('--coarse', type=float, default=5.0, help='Coarse step (mm)')
+    parser.add_argument('--fine', type=float, default=0.5, help='Fine step (mm)')
+    parser.add_argument('--range', type=float, default=3.0, help='Fine range around transitions (mm)')
+    parser.add_argument('--threshold', type=float, default=0.1, help='Change threshold (0-1)')
+    args = parser.parse_args()
+
+    os.makedirs(args.output_dir, exist_ok=True)
+
+    print(f"Loading: {args.stl_file}")
+    mesh = trimesh.load_mesh(args.stl_file, force='mesh')
+    trimesh.repair.fix_normals(mesh)
+
+    dims = mesh.extents
+    print(f"Mesh: {len(mesh.vertices)} verts, {len(mesh.faces)} faces, vol={mesh.volume:.1f}mm³")
+    print(f"Dimensions: {dims[0]:.1f} x {dims[1]:.1f} x {dims[2]:.1f} mm")
+    print(f"Coarse: {args.coarse}mm, Fine: {args.fine}mm, Range: ±{args.range}mm")
+    print()
+
+    # Slice on all 3 axes
+    print("=== Adaptive Multi-Axis Slicing ===")
+    axis_results = []
+    for axis in range(3):
+        result = adaptive_slice_axis(
+            mesh, axis,
+            coarse_step=args.coarse,
+            fine_step=args.fine,
+            fine_range=args.range,
+            threshold=args.threshold,
+        )
+        axis_results.append(result)
+
+    # Build feature map
+    print("\n=== Feature Map ===")
+    features = build_feature_map(axis_results)
+    for f in features:
+        print(f"  {f['axis']} [{f['from']:.1f} → {f['to']:.1f}]: "
+              f"{f['type']} (area={f['avg_area']:.0f}, contours={f['contours']}, holes={f['holes']})")
+
+    # Summary
+    print(f"\n=== Summary ===")
+    total_slices = sum(r['n_total'] for r in axis_results)
+    total_coarse = sum(r['n_coarse'] for r in axis_results)
+    total_fine = sum(r['n_fine'] for r in axis_results)
+    total_trans = sum(len(r['transitions']) for r in axis_results)
+    print(f"Total slices: {total_slices} ({total_coarse} coarse + {total_fine} fine)")
+    print(f"Transitions detected: {total_trans}")
+    print(f"Feature zones: {len(features)}")
+
+    # Save results
+    output = {
+        'file': args.stl_file,
+        'dimensions': dims.tolist(),
+        'volume': float(mesh.volume),
+        'settings': {
+            'coarse_step': args.coarse,
+            'fine_step': args.fine,
+            'fine_range': args.range,
+            'threshold': args.threshold,
+        },
+        'axes': [{
+            'axis': r['axis'],
+            'extent': r['extent'],
+            'n_slices': r['n_total'],
+            'transitions': r['transitions'],
+        } for r in axis_results],
+        'features': features,
+        'total_slices': total_slices,
+        'total_transitions': total_trans,
+    }
+
+    output_path = os.path.join(args.output_dir, 'adaptive-slicing.json')
+    with open(output_path, 'w') as f:
+        json.dump(output, f, indent=2)
+    print(f"\nResults saved to: {output_path}")
+
+
+if __name__ == '__main__':
+    main()

skills/openscad/scripts/openscad-profile-extract.py

@@ -0,0 +1,320 @@
+#!/usr/bin/env python3
+"""
+openscad-profile-extract.py — Extract 2D profiles from STL meshes
+
+Detects the extrusion axis, extracts the dominant cross-section profile,
+and generates OpenSCAD polygon() + linear_extrude() code.
+
+Usage:
+    python3 openscad-profile-extract.py <file.stl> [--output <file.scad>] [--simplify <tolerance>]
+"""
+
+import numpy as np
+import trimesh
+from trimesh import intersections
+import json
+import sys
+import argparse
+
+
+def segments_to_polygons(segments, snap=1e-4):
+    """Convert line segments from mesh slicing to polygons using Shapely."""
+    from shapely.geometry import MultiLineString
+    from shapely.ops import polygonize
+
+    lines = []
+    for seg in np.asarray(segments):
+        a = tuple(np.round(seg[0] / snap) * snap)
+        b = tuple(np.round(seg[1] / snap) * snap)
+        if a != b:
+            lines.append([a, b])
+
+    if not lines:
+        return []
+
+    return [p for p in polygonize(MultiLineString(lines)) if p.area > snap * snap]
+
+
+def detect_extrusion_axis(mesh, n_slices=64):
+    """Find the best extrusion axis by measuring cross-section stability.
+
+    Returns: (stability_score, axis_index, transform, heights, polygons_per_slice)
+    The axis with the LOWEST stability score is the extrusion direction.
+    """
+    # Use OBB for canonical alignment
+    try:
+        T = np.linalg.inv(mesh.bounding_box_oriented.primitive.transform)
+    except Exception:
+        T = np.eye(4)
+
+    m = mesh.copy()
+    m.apply_transform(T)
+
+    best = None
+    axis_names = ['X', 'Y', 'Z']
+
+    for axis in range(3):
+        lo, hi = m.bounds[0][axis], m.bounds[1][axis]
+        margin = (hi - lo) * 0.02
+        heights = np.linspace(lo + margin, hi - margin, n_slices)
+
+        try:
+            segments, _, _ = intersections.mesh_multiplane(
+                m,
+                plane_origin=np.zeros(3),
+                plane_normal=np.eye(3)[axis],
+                heights=heights,
+            )
+        except Exception:
+            continue
+
+        desc = []
+        polys_by_slice = []
+        for segs in segments:
+            polys = segments_to_polygons(segs)
+            polys_by_slice.append(polys)
+            if not polys:
+                desc.append([0, 0, 0, 0])
+                continue
+            from shapely.ops import unary_union
+            u = unary_union(polys)
+            n_holes = sum(len(p.interiors) for p in polys)
+            desc.append([u.area, u.length, n_holes, len(polys)])
+
+        if len([d for d in desc if d[0] > 0]) < n_slices // 3:
+            continue
+
+        arr = np.asarray(desc, dtype=float)
+        nonzero = arr[arr[:, 0] > 0]
+        if len(nonzero) < 3:
+            continue
+
+        # Stability = low variance in area/perimeter/holes across slices
+        means = nonzero.mean(axis=0)
+        means[means < 1e-6] = 1e-6
+        stability = np.mean(np.std(nonzero / means, axis=0))
+
+        extent = hi - lo
+        item = (stability, axis, T, heights, polys_by_slice, extent)
+        if best is None or item[0] < best[0]:
+            best = item
+
+        print(f"  Axis {axis_names[axis]}: stability={stability:.4f}, "
+              f"extent={extent:.1f}mm, non-empty={len(nonzero)}/{n_slices}")
+
+    return best
+
+
+def extract_dominant_profile(polys_by_slice, simplify_tol=0.1):
+    """Find the slice with the largest area and return its simplified polygon."""
+    from shapely.ops import unary_union
+
+    best_area = 0
+    best_poly = None
+    best_idx = 0
+
+    for i, polys in enumerate(polys_by_slice):
+        if not polys:
+            continue
+        u = unary_union(polys)
+        if u.area > best_area:
+            best_area = u.area
+            best_poly = u
+            best_idx = i
+
+    if best_poly is None:
+        return None, 0
+
+    # Simplify to remove tessellation noise
+    simplified = best_poly.simplify(simplify_tol, preserve_topology=True)
+    return simplified, best_idx
+
+
+def polygon_to_scad(poly, var_name="profile"):
+    """Convert a Shapely polygon to OpenSCAD polygon() code."""
+    points = []
+    paths = []
+
+    # Outer boundary
+    exterior_coords = np.asarray(poly.exterior.coords[:-1], dtype=float)
+    start = 0
+    for coord in exterior_coords:
+        points.append(list(np.round(coord, 3)))
+    paths.append(list(range(start, start + len(exterior_coords))))
+
+    # Holes (inner boundaries)
+    for interior in poly.interiors:
+        interior_coords = np.asarray(interior.coords[:-1], dtype=float)
+        start = len(points)
+        for coord in interior_coords:
+            points.append(list(np.round(coord, 3)))
+        # Reverse winding for holes
+        paths.append(list(reversed(range(start, start + len(interior_coords)))))
+
+    # Format as OpenSCAD
+    pts_str = ",\n        ".join(f"[{p[0]}, {p[1]}]" for p in points)
+    paths_str = ", ".join(f"{p}" for p in paths)
+
+    return f"""module {var_name}() {{
+    polygon(
+        points = [
+        {pts_str}
+        ],
+        paths = [{paths_str}]
+    );
+}}"""
+
+
+def analyze_hole_variations(polys_by_slice, heights, dominant_idx):
+    """Detect features that vary along the extrusion axis (holes appearing/disappearing)."""
+    from shapely.ops import unary_union
+
+    dominant_polys = polys_by_slice[dominant_idx]
+    if not dominant_polys:
+        return []
+
+    dom_union = unary_union(dominant_polys)
+    dom_holes = sum(len(p.interiors) for p in dominant_polys)
+
+    variations = []
+    for i, (polys, h) in enumerate(zip(polys_by_slice, heights)):
+        if not polys:
+            continue
+        u = unary_union(polys)
+        n_holes = sum(len(p.interiors) for p in polys)
+        n_parts = len(polys)
+
+        if n_holes != dom_holes or n_parts != len(dominant_polys):
+            variations.append({
+                'height': round(float(h), 3),
+                'slice_idx': i,
+                'holes': n_holes,
+                'parts': n_parts,
+                'area': round(float(u.area), 2),
+                'dom_holes': dom_holes,
+                'dom_parts': len(dominant_polys),
+            })
+
+    return variations
+
+
+def generate_scad(profile_poly, extrusion_length, axis, variations=None):
+    """Generate complete OpenSCAD file from extracted profile."""
+    profile_code = polygon_to_scad(profile_poly, "extracted_profile")
+
+    # Determine extrusion direction
+    axis_names = ['X', 'Y', 'Z']
+
+    scad = f"""// ============================================
+// Auto-generated from STL profile extraction
+// Extrusion axis: {axis_names[axis]}, length: {extrusion_length:.3f}mm
+// Profile points: {len(profile_poly.exterior.coords) - 1}
+// Profile holes: {len(profile_poly.interiors)}
+// ============================================
+
+// --- Parameters ---
+extrusion_length = {extrusion_length:.3f};
+
+// --- Quality ---
+$fn = 64;
+eps = 0.01;
+
+// --- Extracted 2D Profile ---
+{profile_code}
+
+// --- Main Body ---
+// Sculptor approach: extrude profile, then subtract features
+difference() {{
+    // Primary body from extracted profile
+    linear_extrude(height = extrusion_length)
+        extracted_profile();
+
+    // TODO: Add subtractive features (holes, counterbores, chamfers)
+    // detected from cross-section variations
+"""
+
+    if variations:
+        scad += f"\n    // Feature variations detected at {len(variations)} heights:\n"
+        for v in variations[:10]:  # Limit output
+            scad += f"    // Z={v['height']}: {v['holes']} holes, {v['parts']} parts (dominant: {v['dom_holes']} holes, {v['dom_parts']} parts)\n"
+
+    scad += "}\n"
+    return scad
+
+
+def main():
+    parser = argparse.ArgumentParser(description='Extract 2D profile from STL mesh')
+    parser.add_argument('stl_file', help='Input STL file')
+    parser.add_argument('--output', '-o', help='Output .scad file')
+    parser.add_argument('--simplify', type=float, default=0.1,
+                        help='Profile simplification tolerance (mm)')
+    parser.add_argument('--slices', type=int, default=64,
+                        help='Number of slices per axis')
+    parser.add_argument('--json', help='Output analysis as JSON')
+    args = parser.parse_args()
+
+    print(f"Loading: {args.stl_file}")
+    mesh = trimesh.load_mesh(args.stl_file, force='mesh')
+    trimesh.repair.fix_normals(mesh)
+
+    print(f"Mesh: {len(mesh.vertices)} verts, {len(mesh.faces)} faces, "
+          f"vol={mesh.volume:.1f}mm³")
+    print(f"Bounds: {mesh.bounds[0].round(3)} to {mesh.bounds[1].round(3)}")
+    dims = mesh.extents
+    print(f"Dimensions: {dims[0]:.3f} x {dims[1]:.3f} x {dims[2]:.3f} mm")
+
+    print(f"\nDetecting extrusion axis ({args.slices} slices per axis)...")
+    result = detect_extrusion_axis(mesh, n_slices=args.slices)
+
+    if result is None:
+        print("ERROR: Could not detect extrusion axis")
+        sys.exit(1)
+
+    stability, axis, T, heights, polys_by_slice, extent = result
+    axis_names = ['X', 'Y', 'Z']
+    print(f"\nBest extrusion axis: {axis_names[axis]} "
+          f"(stability={stability:.4f}, extent={extent:.1f}mm)")
+
+    print("Extracting dominant profile...")
+    profile, dom_idx = extract_dominant_profile(polys_by_slice, args.simplify)
+
+    if profile is None:
+        print("ERROR: Could not extract profile")
+        sys.exit(1)
+
+    n_pts = len(profile.exterior.coords) - 1
+    n_holes = len(profile.interiors)
+    print(f"Profile: {n_pts} points, {n_holes} holes, area={profile.area:.1f}mm²")
+
+    print("Analyzing feature variations along extrusion axis...")
+    variations = analyze_hole_variations(polys_by_slice, heights, dom_idx)
+    print(f"Found {len(variations)} slices with different features")
+
+    # Generate OpenSCAD
+    scad_code = generate_scad(profile, extent, axis, variations)
+
+    if args.output:
+        with open(args.output, 'w') as f:
+            f.write(scad_code)
+        print(f"\nOpenSCAD saved to: {args.output}")
+    else:
+        print(f"\n--- Generated OpenSCAD ---")
+        print(scad_code)
+
+    if args.json:
+        analysis = {
+            'extrusion_axis': axis_names[axis],
+            'extrusion_length': round(float(extent), 3),
+            'stability_score': round(float(stability), 4),
+            'profile_points': n_pts,
+            'profile_holes': n_holes,
+            'profile_area': round(float(profile.area), 2),
+            'feature_variations': variations[:20],
+        }
+        with open(args.json, 'w') as f:
+            json.dump(analysis, f, indent=2)
+        print(f"Analysis saved to: {args.json}")
+
+
+if __name__ == '__main__':
+    main()

skills/openscad/scripts/openscad-project.sh

@@ -0,0 +1,187 @@
+#!/usr/bin/env bash
+# openscad-project.sh — Project scaffolding and management for OpenSCAD skill
+set -euo pipefail
+
+PROJECTS_ROOT="$HOME/openscad-projects"
+
+usage() {
+    cat <<'EOF'
+Usage: openscad-project.sh <command> [args]
+
+Commands:
+  init  <project-name>     Create a new project directory
+  list                     List all projects
+  clean <project-name>     Remove build artifacts (keep source)
+  info  <project-name>     Show project info and file listing
+
+EOF
+    exit 1
+}
+
+cmd_init() {
+    local name="$1"
+
+    # Sanitize project name to prevent directory traversal
+    if [[ ! "$name" =~ ^[a-zA-Z0-9_-]+$ ]]; then
+        echo "ERROR: Project name must contain only letters, numbers, hyphens, and underscores." >&2
+        exit 1
+    fi
+
+    local project_dir="$PROJECTS_ROOT/$name"
+
+    if [[ -d "$project_dir" ]]; then
+        echo "Project already exists: $project_dir"
+        echo "Use existing project or choose a different name."
+        exit 1
+    fi
+
+    mkdir -p "$project_dir"/{src,output,previews}
+
+    # Create a starter main.scad (name injected directly, no sed needed)
+    cat > "$project_dir/src/main.scad" <<SCAD
+// ============================================
+// Project: $name
+// Description: TODO
+// Author: Claude Code + User
+// ============================================
+
+// --- Parameters (user-configurable) ---
+width = 50;        // [mm] overall width
+height = 30;       // [mm] overall height
+depth = 20;        // [mm] overall depth
+wall = 2.0;        // [mm] wall thickness
+tolerance = 0.3;   // [mm] printer tolerance
+
+// --- Rendering quality ---
+\$fn = 64;          // curve smoothness (use 128+ for final export)
+
+// --- Derived dimensions ---
+inner_width = width - 2 * wall;
+inner_height = height - 2 * wall;
+inner_depth = depth - 2 * wall;
+
+// --- Debug output ---
+echo(str("BBOX: ", width, " x ", depth, " x ", height, " mm"));
+echo(str("Wall: ", wall, " mm | Tolerance: ", tolerance, " mm"));
+
+// --- Main Assembly ---
+// TODO: Replace with your design
+example();
+
+module example() {
+    difference() {
+        cube([width, depth, height], center = true);
+        translate([0, 0, wall])
+            cube([inner_width, inner_depth, inner_height + wall], center = true);
+    }
+}
+SCAD
+
+    # Create a project README
+    cat > "$project_dir/README.md" <<EOF
+# $name
+
+OpenSCAD project created $(date +%Y-%m-%d).
+
+## Structure
+- \`src/\` — OpenSCAD source files (.scad)
+- \`output/\` — Exported STL, 3MF files
+- \`previews/\` — Rendered PNG previews
+
+## Quick Commands
+\`\`\`bash
+# Preview
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh preview src/main.scad
+
+# Export STL
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh stl src/main.scad
+
+# With custom parameters
+bash ~/.claude/skills/openscad/scripts/openscad-render.sh stl src/main.scad -D 'width=60' -D 'height=40'
+\`\`\`
+EOF
+
+    echo "Project created: $project_dir"
+    echo ""
+    echo "Structure:"
+    echo "  $project_dir/"
+    echo "  ├── src/"
+    echo "  │   └── main.scad (starter template)"
+    echo "  ├── output/"
+    echo "  ├── previews/"
+    echo "  └── README.md"
+}
+
+cmd_list() {
+    if [[ ! -d "$PROJECTS_ROOT" ]]; then
+        echo "No projects directory found at $PROJECTS_ROOT"
+        exit 0
+    fi
+
+    echo "OpenSCAD Projects in $PROJECTS_ROOT:"
+    echo ""
+
+    for dir in "$PROJECTS_ROOT"/*/; do
+        [[ ! -d "$dir" ]] && continue
+        local name
+        name="$(basename "$dir")"
+        local scad_count
+        scad_count=$(find "$dir/src" -name "*.scad" 2>/dev/null | wc -l | tr -d ' ')
+        local stl_count
+        stl_count=$(find "$dir/output" -name "*.stl" 2>/dev/null | wc -l | tr -d ' ')
+        local preview_count
+        preview_count=$(find "$dir/previews" -name "*.png" 2>/dev/null | wc -l | tr -d ' ')
+
+        echo "  $name — ${scad_count} .scad, ${stl_count} .stl, ${preview_count} previews"
+    done
+}
+
+cmd_clean() {
+    local name="$1"
+    local project_dir="$PROJECTS_ROOT/$name"
+
+    if [[ ! -d "$project_dir" ]]; then
+        echo "Project not found: $name"
+        exit 1
+    fi
+
+    rm -rf "${project_dir:?}/output/"*
+    rm -rf "${project_dir:?}/previews/"*
+    echo "Cleaned build artifacts for: $name"
+}
+
+cmd_info() {
+    local name="$1"
+    local project_dir="$PROJECTS_ROOT/$name"
+
+    if [[ ! -d "$project_dir" ]]; then
+        echo "Project not found: $name"
+        exit 1
+    fi
+
+    echo "Project: $name"
+    echo "Path: $project_dir"
+    echo ""
+    echo "Source files:"
+    find "$project_dir/src" -name "*.scad" -exec echo "  {}" \; 2>/dev/null
+    echo ""
+    echo "Exports:"
+    find "$project_dir/output" -type f -exec echo "  {}" \; 2>/dev/null || echo "  (none)"
+    echo ""
+    echo "Previews:"
+    find "$project_dir/previews" -name "*.png" -exec echo "  {}" \; 2>/dev/null || echo "  (none)"
+}
+
+# --- Main ---
+[[ $# -lt 1 ]] && usage
+
+command="$1"
+shift
+
+case "$command" in
+    init)  [[ $# -lt 1 ]] && usage; cmd_init "$1" ;;
+    list)  cmd_list ;;
+    clean) [[ $# -lt 1 ]] && usage; cmd_clean "$1" ;;
+    info)  [[ $# -lt 1 ]] && usage; cmd_info "$1" ;;
+    *)     echo "Unknown command: $command"; usage ;;
+esac

skills/openscad/scripts/openscad-render.sh

@@ -0,0 +1,397 @@
+#!/usr/bin/env bash
+# openscad-render.sh — Core render/export/preview engine for OpenSCAD skill
+set -euo pipefail
+
+OPENSCAD="${OPENSCAD_BIN:-$(command -v openscad || echo /opt/homebrew/bin/openscad)}"
+IMGSIZE_PREVIEW="${OPENSCAD_IMGSIZE:-800,600}"
+IMGSIZE_HIRES="1600,1200"
+COLORSCHEME="${OPENSCAD_COLORSCHEME:-DeepOcean}"
+
+usage() {
+    cat <<'EOF'
+Usage: openscad-render.sh <command> <file.scad> [options]
+
+Commands:
+  quick    <file>              Single isometric preview PNG
+  preview  <file>              Multi-angle preview (4 views)
+  stl      <file> [-D ...]     Export STL
+  3mf      <file> [-D ...]     Export 3MF
+  export   <file> [-D ...]     Export STL + 3MF + final PNG
+  analyze  <file>              Render analysis views (cross-sections, bottom)
+  custom   <file> [options]    Custom render with full control
+
+Options (for custom):
+  --format <ext>        Output format (png, stl, 3mf, amf, svg, dxf, pdf)
+  --imgsize <W,H>       Image dimensions
+  --camera <params>     Camera: translate_x,y,z,rot_x,y,z,dist
+  --colorscheme <name>  Color scheme
+  -D 'var=val'          Parameter override (repeatable)
+
+EOF
+    exit 1
+}
+
+# Resolve output directory relative to .scad file
+get_project_dir() {
+    local scad_file="$1"
+    local scad_dir
+    scad_dir="$(dirname "$(realpath "$scad_file")")"
+
+    # If inside a project structure (has src/ parent), go up
+    if [[ "$(basename "$scad_dir")" == "src" ]]; then
+        echo "$(dirname "$scad_dir")"
+    else
+        echo "$scad_dir"
+    fi
+}
+
+ensure_dirs() {
+    local project_dir="$1"
+    mkdir -p "$project_dir/previews" "$project_dir/output"
+}
+
+# Render with error handling
+do_render() {
+    local scad_file="$1"
+    shift
+    local output=""
+    local exit_code=0
+
+    output=$("$OPENSCAD" "$@" "$scad_file" 2>&1) || exit_code=$?
+
+    if [[ $exit_code -ne 0 ]]; then
+        echo "ERROR: OpenSCAD render failed (exit code $exit_code)" >&2
+        echo "$output" >&2
+        # Extract specific error info
+        if echo "$output" | grep -q "Parser error"; then
+            echo "" >&2
+            echo "SYNTAX ERROR detected. Check the .scad file at the reported line." >&2
+        fi
+        return $exit_code
+    fi
+
+    # Check for warnings
+    if echo "$output" | grep -qi "warning"; then
+        echo "WARNINGS:" >&2
+        echo "$output" | grep -i "warning" >&2
+    fi
+
+    # Print render stats
+    if echo "$output" | grep -q "rendering time"; then
+        echo "$output" | grep "rendering time"
+    fi
+    if echo "$output" | grep -q "Facets:"; then
+        echo "$output" | grep -E "(Facets|Vertices):"
+    fi
+
+    echo "$output" | grep -v "^$" | tail -5
+    return 0
+}
+
+cmd_quick() {
+    local scad_file="$1"
+    shift
+    local project_dir
+    project_dir="$(get_project_dir "$scad_file")"
+    ensure_dirs "$project_dir"
+
+    local out="$project_dir/previews/quick-preview.png"
+    echo "Rendering quick preview..."
+    do_render "$scad_file" \
+        --autocenter --viewall \
+        --imgsize="$IMGSIZE_PREVIEW" \
+        --colorscheme="$COLORSCHEME" \
+        --render \
+        -o "$out" \
+        "$@"
+
+    echo "Preview saved: $out"
+}
+
+cmd_preview() {
+    local scad_file="$1"
+    shift
+    local project_dir
+    project_dir="$(get_project_dir "$scad_file")"
+    ensure_dirs "$project_dir"
+
+    local timestamp
+    timestamp="$(date +%Y%m%d-%H%M%S)"
+    local preview_dir="$project_dir/previews"
+
+    # Define camera angles: name, camera_params or flags
+    declare -A views
+    views=(
+        ["1-isometric"]="--autocenter --viewall"
+        ["2-front"]="--autocenter --viewall --projection o --camera 0,0,0,90,0,0,0"
+        ["3-right"]="--autocenter --viewall --projection o --camera 0,0,0,90,0,90,0"
+        ["4-top"]="--autocenter --viewall --projection o --camera 0,0,0,0,0,0,0"
+    )
+
+    local failed=0
+    echo "Rendering 4-view preview..."
+    for view_name in $(echo "${!views[@]}" | tr ' ' '\n' | sort); do
+        local out="$preview_dir/${view_name}-${timestamp}.png"
+        local camera_args="${views[$view_name]}"
+
+        echo "  Rendering $view_name..."
+        # shellcheck disable=SC2086
+        if ! do_render "$scad_file" \
+            $camera_args \
+            --imgsize="$IMGSIZE_PREVIEW" \
+            --colorscheme="$COLORSCHEME" \
+            --render \
+            -o "$out" \
+            "$@"; then
+            echo "  FAILED: $view_name" >&2
+            rm -f "$out"
+            failed=1
+        elif [[ ! -s "$out" ]]; then
+            echo "  ERROR: Empty render output: $out" >&2
+            rm -f "$out"
+            failed=1
+        fi
+    done
+
+    echo ""
+    echo "Preview images saved in: $preview_dir/"
+    ls -la "$preview_dir"/*-"${timestamp}".png 2>/dev/null
+}
+
+cmd_stl() {
+    local scad_file="$1"
+    shift
+    local project_dir
+    project_dir="$(get_project_dir "$scad_file")"
+    ensure_dirs "$project_dir"
+
+    local basename
+    basename="$(basename "$scad_file" .scad)"
+    local out="$project_dir/output/${basename}.stl"
+
+    echo "Exporting STL..."
+    do_render "$scad_file" \
+        --export-format binstl \
+        -o "$out" \
+        "$@"
+
+    local size
+    size=$(wc -c < "$out" | tr -d ' ')
+    echo "STL saved: $out ($size bytes)"
+}
+
+cmd_3mf() {
+    local scad_file="$1"
+    shift
+    local project_dir
+    project_dir="$(get_project_dir "$scad_file")"
+    ensure_dirs "$project_dir"
+
+    local basename
+    basename="$(basename "$scad_file" .scad)"
+    local out="$project_dir/output/${basename}.3mf"
+
+    echo "Exporting 3MF..."
+    do_render "$scad_file" \
+        -o "$out" \
+        "$@"
+
+    local size
+    size=$(wc -c < "$out" | tr -d ' ')
+    echo "3MF saved: $out ($size bytes)"
+}
+
+cmd_export() {
+    local scad_file="$1"
+    shift
+    local project_dir
+    project_dir="$(get_project_dir "$scad_file")"
+    ensure_dirs "$project_dir"
+
+    local basename
+    basename="$(basename "$scad_file" .scad)"
+
+    echo "=== Full Export ==="
+
+    # STL (binary)
+    echo ""
+    echo "--- STL ---"
+    do_render "$scad_file" \
+        --export-format binstl \
+        -o "$project_dir/output/${basename}.stl" \
+        "$@"
+    echo "STL: $project_dir/output/${basename}.stl ($(wc -c < "$project_dir/output/${basename}.stl" | tr -d ' ') bytes)"
+
+    # 3MF
+    echo ""
+    echo "--- 3MF ---"
+    do_render "$scad_file" \
+        -o "$project_dir/output/${basename}.3mf" \
+        "$@" || echo "3MF export failed (may not be supported in this version)"
+
+    # Final high-res preview
+    echo ""
+    echo "--- Final Preview ---"
+    do_render "$scad_file" \
+        --autocenter --viewall \
+        --imgsize="$IMGSIZE_HIRES" \
+        --colorscheme="$COLORSCHEME" \
+        --render \
+        -o "$project_dir/previews/final-preview.png" \
+        "$@"
+
+    echo ""
+    echo "=== Export Complete ==="
+    echo "Output directory: $project_dir/output/"
+    ls -la "$project_dir/output/"
+}
+
+cmd_analyze() {
+    local scad_file="$1"
+    shift
+    local project_dir
+    project_dir="$(get_project_dir "$scad_file")"
+    ensure_dirs "$project_dir"
+
+    local timestamp
+    timestamp="$(date +%Y%m%d-%H%M%S)"
+
+    echo "=== Design Analysis ==="
+
+    # Render STL to get geometry stats
+    echo ""
+    echo "--- Geometry Stats ---"
+    local stl_output
+    stl_output="$project_dir/output/analysis-temp.stl"
+    do_render "$scad_file" \
+        --export-format binstl \
+        -o "$stl_output" \
+        "$@" 2>&1
+
+    if [[ -f "$stl_output" ]]; then
+        local stl_size
+        stl_size=$(wc -c < "$stl_output" | tr -d ' ')
+        echo "STL file size: $stl_size bytes"
+    fi
+
+    # Capture echo output for debug info
+    echo ""
+    echo "--- Echo Output ---"
+    do_render "$scad_file" \
+        -o "$project_dir/output/analysis.echo" \
+        "$@" 2>&1 || echo "Echo capture failed (non-critical)" >&2
+    if [[ -f "$project_dir/output/analysis.echo" ]] && [[ -s "$project_dir/output/analysis.echo" ]]; then
+        cat "$project_dir/output/analysis.echo"
+    fi
+
+    # Bottom view (to check overhangs / first layer)
+    local bottom_png="$project_dir/previews/analysis-bottom-${timestamp}.png"
+    echo ""
+    echo "--- Bottom View (check first layer / overhangs) ---"
+    if ! do_render "$scad_file" \
+        --autocenter --viewall \
+        --camera 0,0,0,180,0,0,0 \
+        --imgsize="$IMGSIZE_PREVIEW" \
+        --colorscheme="$COLORSCHEME" \
+        --render \
+        -o "$bottom_png" \
+        "$@"; then
+        echo "WARNING: Bottom view render failed (may need OpenGL context)" >&2
+        rm -f "$bottom_png"
+    fi
+
+    # Isometric wireframe
+    local wireframe_png="$project_dir/previews/analysis-wireframe-${timestamp}.png"
+    echo ""
+    echo "--- Wireframe View ---"
+    if ! do_render "$scad_file" \
+        --autocenter --viewall \
+        --view edges \
+        --imgsize="$IMGSIZE_PREVIEW" \
+        --colorscheme="$COLORSCHEME" \
+        --render \
+        -o "$wireframe_png" \
+        "$@"; then
+        echo "WARNING: Wireframe render failed (may need OpenGL context)" >&2
+        rm -f "$wireframe_png"
+    fi
+
+    echo ""
+    echo "=== Analysis Complete ==="
+    echo "Review images in: $project_dir/previews/"
+    ls -la "$project_dir/previews"/analysis-*-"${timestamp}".png 2>/dev/null
+
+    # Cleanup temp
+    rm -f "$stl_output"
+}
+
+cmd_custom() {
+    local scad_file="$1"
+    shift
+
+    local format="png"
+    local imgsize="$IMGSIZE_PREVIEW"
+    local camera_args=""
+    local colorscheme="$COLORSCHEME"
+    local extra_args=()
+
+    while [[ $# -gt 0 ]]; do
+        case "$1" in
+            --format) format="$2"; shift 2 ;;
+            --imgsize) imgsize="$2"; shift 2 ;;
+            --camera) camera_args="--camera $2"; shift 2 ;;
+            --colorscheme) colorscheme="$2"; shift 2 ;;
+            -D) extra_args+=(-D "$2"); shift 2 ;;
+            *) extra_args+=("$1"); shift ;;
+        esac
+    done
+
+    local project_dir
+    project_dir="$(get_project_dir "$scad_file")"
+    ensure_dirs "$project_dir"
+
+    local basename
+    basename="$(basename "$scad_file" .scad)"
+    local out="$project_dir/output/${basename}-custom.${format}"
+
+    local render_args=(
+        --imgsize="$imgsize"
+        --colorscheme="$colorscheme"
+        --render
+        -o "$out"
+    )
+
+    if [[ -n "$camera_args" ]]; then
+        # shellcheck disable=SC2086
+        render_args+=($camera_args)
+    else
+        render_args+=(--autocenter --viewall)
+    fi
+
+    do_render "$scad_file" "${render_args[@]}" "${extra_args[@]}"
+    echo "Output: $out"
+}
+
+# --- Main ---
+[[ $# -lt 2 ]] && usage
+
+command="$1"
+scad_file="$2"
+shift 2
+
+# Validate input file
+if [[ ! -f "$scad_file" ]]; then
+    echo "ERROR: File not found: $scad_file" >&2
+    exit 1
+fi
+
+case "$command" in
+    quick)   cmd_quick "$scad_file" "$@" ;;
+    preview) cmd_preview "$scad_file" "$@" ;;
+    stl)     cmd_stl "$scad_file" "$@" ;;
+    3mf)     cmd_3mf "$scad_file" "$@" ;;
+    export)  cmd_export "$scad_file" "$@" ;;
+    analyze) cmd_analyze "$scad_file" "$@" ;;
+    custom)  cmd_custom "$scad_file" "$@" ;;
+    *)       echo "Unknown command: $command"; usage ;;
+esac

skills/openscad/scripts/openscad-sdf-optimize.py

@@ -0,0 +1,342 @@
+#!/usr/bin/env python3
+"""
+openscad-sdf-optimize.py — SDF-based parametric model optimizer
+
+Uses Signed Distance Fields and IoU scoring to find optimal parameters
+for an OpenSCAD reconstruction WITHOUT invoking OpenSCAD in the loop.
+
+Usage:
+    python3 openscad-sdf-optimize.py <original.stl> <model_type> [options]
+
+Model types:
+    stadium-slot    Stadium body with cylindrical slot cut
+    box-holes       Rectangular body with through holes
+    custom          Custom SDF defined in a Python module
+
+Options:
+    --samples N     Number of sample points (default: 30000)
+    --output FILE   Output JSON with optimized parameters
+    --verbose       Print optimization progress
+"""
+
+import numpy as np
+import trimesh
+import json
+import sys
+import os
+from scipy.optimize import minimize, least_squares
+
+
+# ========== SDF Primitives ==========
+
+def sdf_box(p, size):
+    """Signed distance to an axis-aligned box centered at origin."""
+    half = np.array(size) / 2
+    q = np.abs(p) - half
+    return np.linalg.norm(np.maximum(q, 0), axis=1) + np.minimum(np.max(q, axis=1), 0)
+
+
+def sdf_cylinder_x(p, radius, half_length, center=None):
+    """Signed distance to a cylinder along X axis."""
+    if center is not None:
+        p = p - np.array(center)
+    d_yz = np.sqrt(p[:, 1]**2 + p[:, 2]**2) - radius
+    d_x = np.abs(p[:, 0]) - half_length
+    return np.minimum(np.maximum(d_yz, d_x), 0) + np.linalg.norm(
+        np.maximum(np.column_stack([d_yz, d_x]), 0), axis=1)
+
+
+def sdf_capsule_x(p, radius, half_span, center=None):
+    """Signed distance to a capsule (two spheres hulled) along X axis."""
+    if center is not None:
+        p = p - np.array(center)
+    # Clamp X to [-half_span, half_span]
+    px_clamped = np.clip(p[:, 0], -half_span, half_span)
+    q = p.copy()
+    q[:, 0] -= px_clamped
+    return np.linalg.norm(q, axis=1) - radius
+
+
+def sdf_stadium_extrude(p, total_len, width, height):
+    """SDF for a stadium shape extruded along Z."""
+    r = width / 2
+    half_span = total_len / 2 - r
+    # 2D stadium distance in XY
+    px_clamped = np.clip(p[:, 0], -half_span, half_span)
+    dx = p[:, 0] - px_clamped
+    d_xy = np.sqrt(dx**2 + p[:, 1]**2) - r
+    # Z bounds
+    d_z = np.abs(p[:, 2] - height / 2) - height / 2
+    return np.maximum(d_xy, d_z)
+
+
+# ========== CSG Operations ==========
+
+def sdf_union(d1, d2):
+    return np.minimum(d1, d2)
+
+def sdf_difference(d1, d2):
+    return np.maximum(d1, -d2)
+
+def sdf_intersection(d1, d2):
+    return np.maximum(d1, d2)
+
+
+# ========== Model Definitions ==========
+
+def model_stadium_slot(p, params):
+    """Stadium body with cylindrical slot carved from top.
+    params: [length, width, height, slot_total, slot_width, cyl_d, cyl_center_z]
+    """
+    L, W, H, sL, sW, cD, cZ = params
+    body = sdf_stadium_extrude(p, L, W, H)
+    # Cylinder slot along X
+    half_span = sL / 2 - sW / 2
+    cyl = sdf_capsule_x(p, cD / 2, half_span, center=[0, 0, cZ])
+    return sdf_difference(body, cyl)
+
+
+def model_box_with_holes(p, params):
+    """Rectangular box with cylindrical through-holes.
+    params: [sx, sy, sz, hole_d, hole_z, n_holes, hole_spacing, hole_x_start]
+    """
+    sx, sy, sz, hole_d, hole_z, n_holes, spacing, x_start = params
+    n_holes = int(round(n_holes))
+    body = sdf_box(p, [sx, sy, sz])
+    # Offset body center
+    result = body
+    for i in range(n_holes):
+        hx = x_start + i * spacing
+        hole = sdf_cylinder_x(p, hole_d / 2, sy, center=[hx, 0, hole_z - sz/2])
+        # Rotate hole to Y axis
+        p_rot = p.copy()
+        p_rot[:, 0] = p[:, 1]
+        p_rot[:, 1] = p[:, 0]
+        hole = sdf_cylinder_x(p_rot, hole_d / 2, sx, center=[0, hx, hole_z - sz/2])
+        result = sdf_difference(result, hole)
+    return result
+
+
+MODEL_REGISTRY = {
+    'stadium-slot': {
+        'sdf': model_stadium_slot,
+        'param_names': ['length', 'width', 'height', 'slot_total', 'slot_width', 'cyl_d', 'cyl_center_z'],
+    },
+    'box-holes': {
+        'sdf': model_box_with_holes,
+        'param_names': ['sx', 'sy', 'sz', 'hole_d', 'hole_z', 'n_holes', 'spacing', 'x_start'],
+    },
+}
+
+
+# ========== Scoring ==========
+
+def compute_iou(target_inside, candidate_inside):
+    """Intersection over Union from boolean occupancy arrays."""
+    intersection = np.count_nonzero(target_inside & candidate_inside)
+    union = np.count_nonzero(target_inside | candidate_inside)
+    if union == 0:
+        return 0.0
+    return intersection / union
+
+
+def compute_score(mesh, sdf_func, params, sample_points, target_inside):
+    """Score a candidate model against the target mesh."""
+    candidate_sdf = sdf_func(sample_points, params)
+    candidate_inside = candidate_sdf <= 0
+    iou = compute_iou(target_inside, candidate_inside)
+    return iou
+
+
+# ========== Initialization from Mesh Analysis ==========
+
+def init_params_from_mesh(mesh, model_type):
+    """Extract initial parameters from mesh analysis."""
+    bounds = mesh.bounds
+    dims = bounds[1] - bounds[0]
+    center = mesh.centroid
+
+    if model_type == 'stadium-slot':
+        # Use section analysis to find slot
+        sections = []
+        z_min, z_max = bounds[0][2], bounds[1][2]
+        for pct in [0.01, 0.25, 0.5, 0.75, 0.99]:
+            z = z_min + (z_max - z_min) * pct
+            try:
+                path = mesh.section(plane_origin=[0, 0, z], plane_normal=[0, 0, 1])
+                if path:
+                    path2d, _ = path.to_2D()
+                    polys = path2d.polygons_full
+                    areas = [p.area for p in polys]
+                    sections.append({'z': z, 'n_contours': len(polys), 'areas': areas,
+                                     'total_area': sum(areas)})
+            except:
+                pass
+
+        # Estimate slot from difference in areas across Z
+        if sections:
+            body_area = max(s['total_area'] for s in sections)
+            # The slot width can be estimated from how the contour changes
+            # For now, use bounding box as starting point
+            slot_width_est = dims[1] * 0.33  # ~1/3 of body width
+            slot_len_est = dims[0] * 0.89    # ~89% of body length
+
+        return [
+            dims[0],              # length
+            dims[1],              # width
+            dims[2],              # height
+            dims[0] * 0.89,       # slot_total (slightly shorter than body)
+            dims[1] * 0.33,       # slot_width (1/3 of body width)
+            dims[2] * 0.8,        # cyl_d (80% of height)
+            dims[2] * 0.6,        # cyl_center_z (60% up)
+        ]
+
+    return list(dims) + [0] * 4
+
+
+# ========== Main Optimization ==========
+
+def optimize(stl_path, model_type, n_samples=30000, verbose=False):
+    """Main optimization pipeline."""
+    print(f"Loading mesh: {stl_path}")
+    mesh = trimesh.load_mesh(stl_path, force='mesh')
+    trimesh.repair.fix_normals(mesh)
+
+    print(f"Mesh: {len(mesh.vertices)} verts, {len(mesh.faces)} faces, vol={mesh.volume:.1f}mm³")
+
+    # Sample points in and around the bounding box
+    margin = 2.0
+    pts = np.random.uniform(
+        mesh.bounds[0] - margin,
+        mesh.bounds[1] + margin,
+        (n_samples, 3)
+    )
+
+    # Compute target occupancy
+    print("Computing target occupancy...")
+    target_sdf = trimesh.proximity.signed_distance(mesh, pts)
+    target_inside = target_sdf >= 0  # trimesh convention: positive = inside
+
+    print(f"Target: {np.sum(target_inside)}/{n_samples} points inside ({np.mean(target_inside)*100:.1f}%)")
+
+    # Get model SDF function
+    model_info = MODEL_REGISTRY[model_type]
+    sdf_func = model_info['sdf']
+    param_names = model_info['param_names']
+
+    # Initialize parameters from mesh analysis
+    print("Initializing parameters from mesh analysis...")
+    x0 = np.array(init_params_from_mesh(mesh, model_type))
+    print(f"Initial params: {dict(zip(param_names, x0.round(3)))}")
+
+    # Score initial
+    iou0 = compute_score(mesh, sdf_func, x0, pts, target_inside)
+    print(f"Initial IoU: {iou0:.4f} ({iou0*100:.1f}%)")
+
+    # Optimize with Powell method
+    print("\nOptimizing with Powell method...")
+    iter_count = [0]
+
+    def objective(x):
+        iter_count[0] += 1
+        candidate_sdf = sdf_func(pts, x)
+        candidate_inside = candidate_sdf <= 0
+        iou = compute_iou(target_inside, candidate_inside)
+        if verbose and iter_count[0] % 10 == 0:
+            print(f"  iter {iter_count[0]}: IoU={iou:.4f} params={x.round(3)}")
+        return 1.0 - iou  # minimize = maximize IoU
+
+    # Set bounds (all positive, reasonable ranges)
+    dims = mesh.bounds[1] - mesh.bounds[0]
+    bounds_lo = x0 * 0.5
+    bounds_hi = x0 * 1.5
+    # Ensure positive
+    bounds_lo = np.maximum(bounds_lo, 0.1)
+
+    result = minimize(
+        objective, x0,
+        method='Powell',
+        options={'maxiter': 500, 'ftol': 1e-6, 'disp': verbose}
+    )
+
+    final_params = result.x
+    final_iou = 1.0 - result.fun
+
+    print(f"\nOptimization complete ({iter_count[0]} iterations)")
+    print(f"Final IoU: {final_iou:.4f} ({final_iou*100:.1f}%)")
+    print(f"Final params:")
+    for name, val in zip(param_names, final_params):
+        print(f"  {name} = {val:.4f}")
+
+    # Generate OpenSCAD code
+    scad_code = generate_scad(model_type, param_names, final_params)
+    print(f"\n--- Generated OpenSCAD ---\n{scad_code}")
+
+    return {
+        'model_type': model_type,
+        'params': dict(zip(param_names, [round(float(v), 4) for v in final_params])),
+        'iou': round(float(final_iou), 4),
+        'iterations': iter_count[0],
+        'volume_target': round(float(mesh.volume), 2),
+        'scad_code': scad_code,
+    }
+
+
+def generate_scad(model_type, param_names, params):
+    """Generate OpenSCAD code from optimized parameters."""
+    p = dict(zip(param_names, params))
+
+    if model_type == 'stadium-slot':
+        return f"""// Auto-generated by SDF optimizer
+// IoU-optimized parameters
+length = {p['length']:.3f};
+width = {p['width']:.3f};
+height = {p['height']:.3f};
+slot_total = {p['slot_total']:.3f};
+slot_width = {p['slot_width']:.3f};
+cyl_d = {p['cyl_d']:.3f};
+cyl_center_z = {p['cyl_center_z']:.3f};
+
+$fn = 64;
+
+difference() {{
+    linear_extrude(height = height)
+        stadium(length, width);
+    translate([0, 0, cyl_center_z])
+        hull() {{
+            translate([-(slot_total/2 - slot_width/2), 0, 0]) sphere(d=cyl_d, $fn=64);
+            translate([(slot_total/2 - slot_width/2), 0, 0]) sphere(d=cyl_d, $fn=64);
+        }}
+}}
+
+module stadium(l, w) {{
+    r = w / 2;
+    hull() {{
+        translate([-(l/2 - r), 0]) circle(r=r);
+        translate([(l/2 - r), 0]) circle(r=r);
+    }}
+}}
+"""
+    return f"// No code generator for model_type={model_type}"
+
+
+# ========== CLI ==========
+
+if __name__ == '__main__':
+    import argparse
+    parser = argparse.ArgumentParser(description='SDF-based OpenSCAD parameter optimizer')
+    parser.add_argument('stl_file', help='Input STL file')
+    parser.add_argument('model_type', choices=list(MODEL_REGISTRY.keys()),
+                        help='Model type to fit')
+    parser.add_argument('--samples', type=int, default=30000, help='Sample points')
+    parser.add_argument('--output', help='Output JSON file')
+    parser.add_argument('--verbose', action='store_true', help='Show progress')
+    args = parser.parse_args()
+
+    result = optimize(args.stl_file, args.model_type,
+                      n_samples=args.samples, verbose=args.verbose)
+
+    if args.output:
+        with open(args.output, 'w') as f:
+            json.dump(result, f, indent=2)
+        print(f"\nResults saved to {args.output}")

skills/openscad/scripts/openscad-stl-analyze.sh

@@ -0,0 +1,214 @@
+#!/usr/bin/env bash
+# openscad-stl-analyze.sh — Extract geometry data from binary STL files
+# Outputs bounding box, vertex distributions, and internal structure hints
+set -euo pipefail
+
+usage() {
+    cat <<'EOF'
+Usage: openscad-stl-analyze.sh <file.stl> [--cross-section <axis> <value>] [--gaps <axis>]
+
+Commands:
+  <file.stl>                       Full bounding box and triangle count
+  --cross-section <axis> <value>   Show vertex distribution at a cross-section
+                                   axis: x, y, or z; value: coordinate
+  --gaps <axis>                    Find gaps in vertex distribution along axis
+                                   (useful for finding internal features)
+
+Examples:
+  openscad-stl-analyze.sh model.stl
+  openscad-stl-analyze.sh model.stl --cross-section z 0
+  openscad-stl-analyze.sh model.stl --gaps y
+
+EOF
+    exit 1
+}
+
+[[ $# -lt 1 ]] && usage
+
+STL_FILE="$1"
+shift
+
+if [[ ! -f "$STL_FILE" ]]; then
+    echo "ERROR: File not found: $STL_FILE" >&2
+    exit 1
+fi
+
+# Default: full analysis
+if [[ $# -eq 0 ]]; then
+    python3 -c "
+import struct, math, sys
+from collections import defaultdict
+
+path = '$STL_FILE'
+with open(path, 'rb') as f:
+    header = f.read(80)
+    n = struct.unpack('<I', f.read(4))[0]
+    verts = set()
+    for _ in range(n):
+        f.read(12)  # normal
+        for _ in range(3):
+            v = struct.unpack('<3f', f.read(12))
+            verts.add((round(v[0],4), round(v[1],4), round(v[2],4)))
+        f.read(2)
+
+xs = [v[0] for v in verts]
+ys = [v[1] for v in verts]
+zs = [v[2] for v in verts]
+
+print('=== STL Analysis ===')
+print(f'File: {path}')
+print(f'Triangles: {n}')
+print(f'Unique vertices: {len(verts)}')
+print()
+print('=== Bounding Box ===')
+print(f'X: {min(xs):.4f} to {max(xs):.4f} = {max(xs)-min(xs):.4f} mm')
+print(f'Y: {min(ys):.4f} to {max(ys):.4f} = {max(ys)-min(ys):.4f} mm')
+print(f'Z: {min(zs):.4f} to {max(zs):.4f} = {max(zs)-min(zs):.4f} mm')
+print(f'Center: ({(min(xs)+max(xs))/2:.4f}, {(min(ys)+max(ys))/2:.4f}, {(min(zs)+max(zs))/2:.4f})')
+print()
+print('=== Symmetry Check ===')
+cx, cy, cz = (min(xs)+max(xs))/2, (min(ys)+max(ys))/2, (min(zs)+max(zs))/2
+print(f'X symmetric: {abs(cx) < 0.01} (center offset: {cx:.4f})')
+print(f'Y symmetric: {abs(cy) < 0.01} (center offset: {cy:.4f})')
+print(f'Z base at 0: {abs(min(zs)) < 0.01}')
+print()
+print('=== Distinct Values Per Axis ===')
+print(f'Distinct X values: {len(set(round(x,3) for x in xs))}')
+print(f'Distinct Y values: {len(set(round(y,3) for y in ys))}')
+print(f'Distinct Z values: {len(set(round(z,3) for z in zs))}')
+print()
+
+# Gap detection on each axis
+for axis_name, vals in [('X', xs), ('Y', ys), ('Z', zs)]:
+    sorted_unique = sorted(set(round(v,3) for v in vals))
+    gaps = []
+    for i in range(len(sorted_unique)-1):
+        gap = sorted_unique[i+1] - sorted_unique[i]
+        if gap > (max(vals)-min(vals)) * 0.05:  # gaps > 5% of range
+            gaps.append((sorted_unique[i], sorted_unique[i+1], gap))
+    if gaps:
+        print(f'{axis_name}-axis gaps (>5% of range):')
+        for v1, v2, g in gaps:
+            print(f'  {v1:.3f} to {v2:.3f} (gap={g:.3f} mm) — possible internal feature boundary')
+        print()
+"
+    exit 0
+fi
+
+# Cross-section analysis
+if [[ "$1" == "--cross-section" ]]; then
+    [[ $# -lt 3 ]] && usage
+    AXIS="$2"
+    VALUE="$3"
+    python3 -c "
+import struct
+
+path = '$STL_FILE'
+axis = '$AXIS'
+value = float($VALUE)
+
+with open(path, 'rb') as f:
+    f.read(80)
+    n = struct.unpack('<I', f.read(4))[0]
+    verts = set()
+    for _ in range(n):
+        f.read(12)
+        for _ in range(3):
+            v = struct.unpack('<3f', f.read(12))
+            verts.add((round(v[0],4), round(v[1],4), round(v[2],4)))
+        f.read(2)
+
+axis_idx = {'x':0, 'y':1, 'z':2}[axis]
+other_axes = [i for i in range(3) if i != axis_idx]
+axis_names = 'XYZ'
+
+# Find vertices near the cross-section plane
+tolerance = 0.02
+cross_verts = [(v[other_axes[0]], v[other_axes[1]])
+               for v in verts if abs(v[axis_idx] - value) < tolerance]
+
+if not cross_verts:
+    # Widen tolerance
+    tolerance = 0.2
+    cross_verts = [(v[other_axes[0]], v[other_axes[1]])
+                   for v in verts if abs(v[axis_idx] - value) < tolerance]
+
+print(f'=== Cross-section at {axis_names[axis_idx]}={value:.3f} (tol={tolerance}) ===')
+print(f'Found {len(cross_verts)} vertices')
+if cross_verts:
+    a_vals = sorted(set(round(v[0],4) for v in cross_verts))
+    b_vals = sorted(set(round(v[1],4) for v in cross_verts))
+    print(f'{axis_names[other_axes[0]]} range: {min(a_vals):.4f} to {max(a_vals):.4f}')
+    print(f'{axis_names[other_axes[1]]} range: {min(b_vals):.4f} to {max(b_vals):.4f}')
+    print()
+
+    # Show |values| distribution for the narrower axis (usually reveals internal features)
+    for oa, name in [(0, axis_names[other_axes[0]]), (1, axis_names[other_axes[1]])]:
+        abs_vals = sorted(set(round(abs(v[oa]),4) for v in cross_verts))
+        if len(abs_vals) < 80:
+            print(f'|{name}| distribution:')
+            for av in abs_vals:
+                bar = '#' * int(av * 8)
+                print(f'  |{name}|={av:7.4f}  {bar}')
+            print()
+            # Find gaps
+            for i in range(len(abs_vals)-1):
+                gap = abs_vals[i+1] - abs_vals[i]
+                if gap > 0.5:
+                    print(f'  GAP: |{name}|={abs_vals[i]:.4f} to |{name}|={abs_vals[i+1]:.4f} (width={gap:.4f})')
+                    print(f'  -> Possible feature boundary at |{name}|={abs_vals[i]:.4f}')
+"
+    exit 0
+fi
+
+# Gap analysis
+if [[ "$1" == "--gaps" ]]; then
+    [[ $# -lt 2 ]] && usage
+    AXIS="$2"
+    python3 -c "
+import struct
+from collections import defaultdict
+
+path = '$STL_FILE'
+axis = '$AXIS'
+axis_idx = {'x':0, 'y':1, 'z':2}[axis]
+axis_names = 'XYZ'
+
+with open(path, 'rb') as f:
+    f.read(80)
+    n = struct.unpack('<I', f.read(4))[0]
+    verts = set()
+    for _ in range(n):
+        f.read(12)
+        for _ in range(3):
+            v = struct.unpack('<3f', f.read(12))
+            verts.add((round(v[0],4), round(v[1],4), round(v[2],4)))
+        f.read(2)
+
+# Get all distinct values for other axes, grouped by the target axis levels
+other_axes = [i for i in range(3) if i != axis_idx]
+
+# Find distinct levels of the target axis
+levels = sorted(set(round(v[axis_idx], 3) for v in verts))
+print(f'=== {axis_names[axis_idx]}-axis gap analysis ===')
+print(f'Distinct {axis_names[axis_idx]} levels: {len(levels)}')
+print()
+
+for level in levels:
+    level_verts = [v for v in verts if abs(v[axis_idx] - level) < 0.005]
+    for oa in other_axes:
+        abs_vals = sorted(set(round(abs(v[oa]), 4) for v in level_verts))
+        gaps = []
+        for i in range(len(abs_vals)-1):
+            g = abs_vals[i+1] - abs_vals[i]
+            if g > 0.5:
+                gaps.append((abs_vals[i], abs_vals[i+1], g))
+        if gaps:
+            print(f'{axis_names[axis_idx]}={level:6.3f}: |{axis_names[oa]}| gaps:')
+            for v1, v2, g in gaps:
+                print(f'  {v1:.4f} to {v2:.4f} (gap={g:.4f}) — feature boundary')
+"
+    exit 0
+fi
+
+usage

skills/openscad/scripts/openscad-stl-compare.sh

@@ -0,0 +1,220 @@
+#!/usr/bin/env bash
+# openscad-stl-compare.sh — Compare two STL files geometrically
+# Uses OpenSCAD boolean difference + Python mesh distance analysis
+set -euo pipefail
+
+OPENSCAD="${OPENSCAD_BIN:-$(command -v openscad || echo /opt/homebrew/bin/openscad)}"
+IMGSIZE="${OPENSCAD_IMGSIZE:-800,600}"
+
+usage() {
+    cat <<'EOF'
+Usage: openscad-stl-compare.sh <original.stl> <reconstruction.stl> [output_dir]
+
+Compares two STL files and reports:
+  1. Bounding box comparison
+  2. Volume/triangle count comparison
+  3. Boolean difference renders (what's in A but not B, and vice versa)
+  4. Point-to-mesh distance statistics (Hausdorff, RMS, mean)
+
+Output:
+  <output_dir>/diff-A-minus-B.png    — Geometry in original but NOT in reconstruction
+  <output_dir>/diff-B-minus-A.png    — Geometry in reconstruction but NOT in original
+  <output_dir>/overlay.png           — Both overlaid (original=transparent, recon=red)
+  <output_dir>/comparison-report.txt — Full numerical report
+
+EOF
+    exit 1
+}
+
+[[ $# -lt 2 ]] && usage
+
+STL_A="$(cd "$(dirname "$1")" && pwd)/$(basename "$1")"
+STL_B="$(cd "$(dirname "$2")" && pwd)/$(basename "$2")"
+OUTDIR="${3:-/tmp/stl-compare-$(date +%s)}"
+
+[[ -f "$STL_A" ]] || { echo "ERROR: File not found: $STL_A" >&2; exit 1; }
+[[ -f "$STL_B" ]] || { echo "ERROR: File not found: $STL_B" >&2; exit 1; }
+
+mkdir -p "$OUTDIR"
+TMPDIR=$(mktemp -d /tmp/stl-compare-XXXXXX)
+trap 'rm -rf "$TMPDIR"' EXIT
+
+echo "=== STL Mesh Comparison ==="
+echo "A (original):       $STL_A"
+echo "B (reconstruction): $STL_B"
+echo "Output:             $OUTDIR"
+echo ""
+
+# --- Step 1: Bounding box + triangle comparison ---
+echo "--- Dimensional Comparison ---"
+python3 -c "
+import struct, sys
+
+def parse_stl(path):
+    with open(path, 'rb') as f:
+        header = f.read(80)
+        n = struct.unpack('<I', f.read(4))[0]
+        mn = [float('inf')]*3
+        mx = [float('-inf')]*3
+        for _ in range(n):
+            f.read(12)
+            for _ in range(3):
+                v = struct.unpack('<3f', f.read(12))
+                for i in range(3):
+                    mn[i] = min(mn[i], v[i])
+                    mx[i] = max(mx[i], v[i])
+            f.read(2)
+    return n, mn, mx
+
+n_a, mn_a, mx_a = parse_stl('$STL_A')
+n_b, mn_b, mx_b = parse_stl('$STL_B')
+
+print(f'                  Original         Reconstruction   Delta')
+print(f'Triangles:        {n_a:>8}         {n_b:>8}')
+labels = ['X', 'Y', 'Z']
+total_delta = 0
+for i in range(3):
+    da = mx_a[i] - mn_a[i]
+    db = mx_b[i] - mn_b[i]
+    delta = abs(db - da)
+    total_delta += delta
+    print(f'{labels[i]} dimension:  {da:>12.4f} mm   {db:>12.4f} mm   {delta:>8.4f} mm')
+    # Also check position offset
+    ca = (mn_a[i] + mx_a[i]) / 2
+    cb = (mn_b[i] + mx_b[i]) / 2
+    if abs(ca - cb) > 0.01:
+        print(f'  Center offset: {abs(ca-cb):.4f} mm')
+
+print(f'Total dim delta:                                   {total_delta:>8.4f} mm')
+"
+
+# --- Step 2: Boolean difference renders ---
+echo ""
+echo "--- Boolean Difference Renders ---"
+
+# A - B: what's in original but not reconstruction
+cat > "$TMPDIR/diff-a-minus-b.scad" << SCAD
+difference() {
+    import("$STL_A", convexity=10);
+    import("$STL_B", convexity=10);
+}
+SCAD
+
+# B - A: what's in reconstruction but not original
+cat > "$TMPDIR/diff-b-minus-a.scad" << SCAD
+difference() {
+    import("$STL_B", convexity=10);
+    import("$STL_A", convexity=10);
+}
+SCAD
+
+# Overlay
+cat > "$TMPDIR/overlay.scad" << SCAD
+%import("$STL_A", convexity=10);
+color("red", 0.5) import("$STL_B", convexity=10);
+SCAD
+
+# Render A-B
+echo "  Rendering A-B (in original, missing from reconstruction)..."
+if "$OPENSCAD" --autocenter --viewall --imgsize="$IMGSIZE" --colorscheme=DeepOcean \
+    --render -o "$OUTDIR/diff-A-minus-B.png" "$TMPDIR/diff-a-minus-b.scad" 2>"$TMPDIR/ab.log"; then
+    # Check if the difference produced any geometry
+    if grep -q "Top level object is a 3D object" "$TMPDIR/ab.log"; then
+        facets=$(grep "Facets:" "$TMPDIR/ab.log" | tail -1 | grep -oE '[0-9]+')
+        echo "    Difference has $facets facets"
+    fi
+    # Also export the difference as STL for volume analysis
+    "$OPENSCAD" --render --export-format binstl \
+        -o "$TMPDIR/diff-ab.stl" "$TMPDIR/diff-a-minus-b.scad" 2>/dev/null || true
+else
+    echo "    Render failed" >&2
+    rm -f "$OUTDIR/diff-A-minus-B.png"
+fi
+
+# Render B-A
+echo "  Rendering B-A (in reconstruction, not in original)..."
+if "$OPENSCAD" --autocenter --viewall --imgsize="$IMGSIZE" --colorscheme=DeepOcean \
+    --render -o "$OUTDIR/diff-B-minus-A.png" "$TMPDIR/diff-b-minus-a.scad" 2>"$TMPDIR/ba.log"; then
+    if grep -q "Top level object is a 3D object" "$TMPDIR/ba.log"; then
+        facets=$(grep "Facets:" "$TMPDIR/ba.log" | tail -1 | grep -oE '[0-9]+')
+        echo "    Difference has $facets facets"
+    fi
+    "$OPENSCAD" --render --export-format binstl \
+        -o "$TMPDIR/diff-ba.stl" "$TMPDIR/diff-b-minus-a.scad" 2>/dev/null || true
+else
+    echo "    Render failed" >&2
+    rm -f "$OUTDIR/diff-B-minus-A.png"
+fi
+
+# Render overlay
+echo "  Rendering overlay..."
+"$OPENSCAD" --autocenter --viewall --imgsize="$IMGSIZE" --colorscheme=Cornfield \
+    -o "$OUTDIR/overlay.png" "$TMPDIR/overlay.scad" 2>/dev/null || true
+
+# --- Step 3: Volume analysis of differences ---
+echo ""
+echo "--- Difference Volume Analysis ---"
+python3 -c "
+import struct, os
+
+def stl_volume(path):
+    '''Calculate volume of a binary STL using signed tetrahedron method'''
+    if not os.path.exists(path):
+        return 0, 0
+    with open(path, 'rb') as f:
+        f.read(80)
+        n = struct.unpack('<I', f.read(4))[0]
+        if n == 0:
+            return 0, 0
+        volume = 0.0
+        for _ in range(n):
+            f.read(12)  # normal
+            v1 = struct.unpack('<3f', f.read(12))
+            v2 = struct.unpack('<3f', f.read(12))
+            v3 = struct.unpack('<3f', f.read(12))
+            f.read(2)
+            # Signed volume of tetrahedron with origin
+            volume += (
+                v1[0] * (v2[1]*v3[2] - v2[2]*v3[1]) +
+                v1[1] * (v2[2]*v3[0] - v2[0]*v3[2]) +
+                v1[2] * (v2[0]*v3[1] - v2[1]*v3[0])
+            ) / 6.0
+        return n, abs(volume)
+
+n_a, vol_a = stl_volume('$STL_A')
+n_b, vol_b = stl_volume('$STL_B')
+n_ab, vol_ab = stl_volume('$TMPDIR/diff-ab.stl')
+n_ba, vol_ba = stl_volume('$TMPDIR/diff-ba.stl')
+
+print(f'Original volume:       {vol_a:>12.2f} mm³')
+print(f'Reconstruction volume: {vol_b:>12.2f} mm³')
+print(f'Volume delta:          {abs(vol_b - vol_a):>12.2f} mm³ ({abs(vol_b-vol_a)/max(vol_a,1)*100:.2f}%)')
+print()
+print(f'A-B (missing from recon): {vol_ab:>10.2f} mm³ ({n_ab} triangles)')
+print(f'B-A (extra in recon):     {vol_ba:>10.2f} mm³ ({n_ba} triangles)')
+print()
+
+total_error = vol_ab + vol_ba
+if vol_a > 0:
+    accuracy = (1 - total_error / vol_a) * 100
+    print(f'Total error volume:       {total_error:>10.2f} mm³')
+    print(f'Geometric accuracy:       {accuracy:>10.2f}%')
+    print()
+    if accuracy > 99:
+        print('Result: EXCELLENT match')
+    elif accuracy > 95:
+        print('Result: Good match (minor differences)')
+    elif accuracy > 90:
+        print('Result: Fair match (visible differences)')
+    else:
+        print('Result: Needs significant refinement')
+" 2>&1 || echo "Volume analysis failed (non-manifold geometry?)"
+
+# --- Step 4: Summary ---
+echo ""
+echo "--- Output Files ---"
+ls -la "$OUTDIR"/*.png 2>/dev/null || echo "No PNG files generated"
+echo ""
+echo "View difference images to see WHERE the models differ."
+echo "  diff-A-minus-B.png = geometry in original but MISSING from reconstruction"
+echo "  diff-B-minus-A.png = EXTRA geometry in reconstruction not in original"

skills/openscad/scripts/openscad-stl-reconstruct.sh

@@ -0,0 +1,215 @@
+#!/usr/bin/env bash
+# openscad-stl-reconstruct.sh — Automated STL analysis for reconstruction
+# Uses projection slicing, trimesh analysis, and normal-based CSG inference
+set -euo pipefail
+
+OPENSCAD="${OPENSCAD_BIN:-$(command -v openscad || echo /opt/homebrew/bin/openscad)}"
+
+usage() {
+    cat <<'EOF'
+Usage: openscad-stl-reconstruct.sh <file.stl> <output_dir>
+
+Automated STL analysis pipeline:
+  1. Bounding box + volume + basic mesh stats (via trimesh/admesh)
+  2. 2D profile slices at multiple Z levels (via OpenSCAD projection)
+  3. Normal analysis for CSG inference (cuts vs solid features)
+  4. Primitive detection (RANSAC plane/cylinder fitting)
+  5. Generates a decomposition report with OpenSCAD code suggestions
+
+Output:
+  <output_dir>/report.txt              Full analysis report
+  <output_dir>/slices/slice-z*.svg     2D profile SVGs at each Z level
+  <output_dir>/slices/slice-z*.png     Rendered slice images
+  <output_dir>/primitives.json         Detected primitives with parameters
+
+EOF
+    exit 1
+}
+
+[[ $# -lt 2 ]] && usage
+
+STL_FILE="$(cd "$(dirname "$1")" && pwd)/$(basename "$1")"
+OUTDIR="$2"
+
+[[ -f "$STL_FILE" ]] || { echo "ERROR: File not found: $STL_FILE" >&2; exit 1; }
+
+mkdir -p "$OUTDIR/slices"
+
+echo "=== STL Reconstruction Analysis ==="
+echo "Input: $STL_FILE"
+echo "Output: $OUTDIR"
+echo ""
+
+# --- Step 1: Basic mesh analysis with trimesh ---
+echo "--- Step 1: Mesh Analysis ---"
+python3 << PYEOF
+import trimesh
+import numpy as np
+import json, os
+
+mesh = trimesh.load_mesh('$STL_FILE', force='mesh')
+
+print(f"Vertices: {len(mesh.vertices)}")
+print(f"Faces: {len(mesh.faces)}")
+print(f"Volume: {mesh.volume:.2f} mm³")
+print(f"Watertight: {mesh.is_watertight}")
+print(f"Bounding box: {mesh.bounds[0].round(3)} to {mesh.bounds[1].round(3)}")
+dims = mesh.bounds[1] - mesh.bounds[0]
+print(f"Dimensions: {dims[0]:.3f} x {dims[1]:.3f} x {dims[2]:.3f} mm")
+print(f"Center: {mesh.centroid.round(3)}")
+
+# Identify the primary axes (longest = extrusion direction)
+axes = ['X', 'Y', 'Z']
+sorted_axes = sorted(range(3), key=lambda i: dims[i], reverse=True)
+print(f"Primary axis (longest): {axes[sorted_axes[0]]} ({dims[sorted_axes[0]]:.1f}mm)")
+print(f"Likely extrusion axis: {axes[sorted_axes[0]]}")
+
+# Bounding cylinder
+try:
+    cyl = trimesh.bounds.minimum_cylinder(mesh)
+    print(f"Bounding cylinder: h={cyl['height']:.2f} r={cyl['radius']:.2f}")
+except:
+    pass
+
+# Face normal analysis — detect dominant orientations
+normals = mesh.face_normals
+# Cluster normals by major axis alignment
+for i, axis in enumerate(axes):
+    pos = np.sum(normals[:, i] > 0.9)
+    neg = np.sum(normals[:, i] < -0.9)
+    if pos + neg > 0:
+        print(f"Faces aligned with {axis}: +{pos} / -{neg}")
+
+# Detect inward-facing curved surfaces (= cuts/holes)
+# Curved faces have normals NOT aligned with any axis
+non_planar = np.sum(np.all(np.abs(normals) < 0.9, axis=1))
+print(f"Curved/non-planar faces: {non_planar} ({non_planar/len(normals)*100:.0f}%)")
+
+# Save basic info as JSON
+info = {
+    'file': '$STL_FILE',
+    'vertices': int(len(mesh.vertices)),
+    'faces': int(len(mesh.faces)),
+    'volume': float(mesh.volume),
+    'watertight': bool(mesh.is_watertight),
+    'bounds_min': mesh.bounds[0].tolist(),
+    'bounds_max': mesh.bounds[1].tolist(),
+    'dimensions': dims.tolist(),
+    'center': mesh.centroid.tolist(),
+    'primary_axis': axes[sorted_axes[0]],
+}
+with open('$OUTDIR/mesh-info.json', 'w') as f:
+    json.dump(info, f, indent=2)
+
+PYEOF
+
+# --- Step 2: 2D Profile Slices via OpenSCAD projection ---
+echo ""
+echo "--- Step 2: 2D Profile Slices ---"
+
+# Get Z range from mesh info
+Z_MIN=$(python3 -c "import json; d=json.load(open('$OUTDIR/mesh-info.json')); print(d['bounds_min'][2])")
+Z_MAX=$(python3 -c "import json; d=json.load(open('$OUTDIR/mesh-info.json')); print(d['bounds_max'][2])")
+Z_MID=$(python3 -c "print(($Z_MIN + $Z_MAX) / 2)")
+
+echo "Z range: $Z_MIN to $Z_MAX (mid=$Z_MID)"
+
+# Generate slices at key Z levels (bottom, 25%, 50%, 75%, top)
+for pct in 0.01 0.25 0.50 0.75 0.99; do
+    Z_LEVEL=$(python3 -c "print(round($Z_MIN + ($Z_MAX - $Z_MIN) * $pct, 3))")
+    SLICE_NAME="slice-z${Z_LEVEL}"
+
+    # Create OpenSCAD file for this slice
+    cat > "/tmp/slice-${pct}.scad" << SCADEOF
+projection(cut=true)
+    translate([0, 0, -${Z_LEVEL}])
+        import("${STL_FILE}", convexity=10);
+SCADEOF
+
+    # Export as SVG
+    if "$OPENSCAD" -o "$OUTDIR/slices/${SLICE_NAME}.svg" "/tmp/slice-${pct}.scad" 2>/dev/null; then
+        SVG_SIZE=$(wc -c < "$OUTDIR/slices/${SLICE_NAME}.svg" | tr -d ' ')
+        if [[ "$SVG_SIZE" -gt 200 ]]; then
+            echo "  Z=$Z_LEVEL (${pct}): SVG exported ($SVG_SIZE bytes)"
+        else
+            echo "  Z=$Z_LEVEL (${pct}): Empty slice (no geometry at this Z)"
+            rm -f "$OUTDIR/slices/${SLICE_NAME}.svg"
+        fi
+    else
+        echo "  Z=$Z_LEVEL (${pct}): Export failed"
+    fi
+done
+
+# --- Step 3: Primitive Detection with trimesh ---
+echo ""
+echo "--- Step 3: Primitive Detection ---"
+python3 -c "
+import trimesh
+import numpy as np
+import json
+
+mesh = trimesh.load_mesh('$STL_FILE', force='mesh')
+primitives = []
+
+# Planar facets
+try:
+    for i, (facet, area) in enumerate(zip(mesh.facets, mesh.facets_area)):
+        if area > 10:
+            fn = mesh.face_normals[facet]
+            avg_n = fn.mean(axis=0); avg_n /= np.linalg.norm(avg_n)
+            fv = mesh.vertices[mesh.faces[facet].flatten()]
+            primitives.append({'type':'plane','normal':avg_n.round(4).tolist(),'centroid':fv.mean(axis=0).round(3).tolist(),'area':round(float(area),2),'faces':len(facet)})
+except Exception as e:
+    print(f'Facet error: {e}')
+
+# Cylindrical surfaces
+normals = mesh.face_normals
+curved_mask = np.all(np.abs(normals) < 0.85, axis=1)
+curved_faces = np.where(curved_mask)[0]
+print(f'Planar facets: {len([p for p in primitives if p[\"type\"]==\"plane\"])} (>{\"10mm²\"})')
+print(f'Curved faces: {len(curved_faces)} ({len(curved_faces)/len(normals)*100:.0f}%)')
+
+if len(curved_faces) > 10:
+    cv = mesh.vertices[np.unique(mesh.faces[curved_faces].flatten())]
+    cn = mesh.face_normals[curved_faces]
+    # Axis from normal cross products
+    axes_c = []
+    for _ in range(min(200, len(cn))):
+        i,j = np.random.choice(len(cn),2,replace=False)
+        cp = np.cross(cn[i],cn[j])
+        if np.linalg.norm(cp) > 0.1:
+            cp /= np.linalg.norm(cp)
+            if cp[0] < 0: cp *= -1
+            axes_c.append(cp)
+    if axes_c:
+        ax = np.mean(axes_c, axis=0); ax /= np.linalg.norm(ax)
+        # Project to 2D for circle fitting
+        if abs(ax[0]) < 0.9: u = np.cross(ax,[1,0,0])
+        else: u = np.cross(ax,[0,1,0])
+        u /= np.linalg.norm(u); v = np.cross(ax,u)
+        c3d = cv.mean(axis=0); centered = cv - c3d
+        pu = centered@u; pv = centered@v; pa = centered@ax
+        r = float(np.median(np.sqrt(pu**2+pv**2)))
+        # Inward/outward
+        fc = mesh.triangles_center[curved_faces]
+        tc = c3d - fc; tc /= (np.linalg.norm(tc,axis=1,keepdims=True)+1e-10)
+        inw = float(np.mean(np.sum(cn*tc,axis=1) > 0))
+        op = 'difference' if inw > 0.5 else 'union'
+        print(f'Cylinder: axis=[{ax[0]:.3f},{ax[1]:.3f},{ax[2]:.3f}] r={r:.3f} d={r*2:.3f} center={c3d.round(2).tolist()} type={op}')
+        print(f'  Axis span: {float(pa.min()):.2f} to {float(pa.max()):.2f}')
+        primitives.append({'type':'cylinder','axis':ax.round(4).tolist(),'radius':round(r,3),'diameter':round(r*2,3),'center':c3d.round(3).tolist(),'axis_min':round(float(pa.min()),3),'axis_max':round(float(pa.max()),3),'csg_operation':op,'inward_ratio':round(inw,3),'faces':int(len(curved_faces))})
+
+with open('$OUTDIR/primitives.json','w') as f:
+    json.dump(primitives,f,indent=2)
+print(f'Saved {len(primitives)} primitives to $OUTDIR/primitives.json')
+"
+
+# --- Step 4: Generate Report ---
+echo ""
+echo "--- Step 4: Report ---"
+echo "Profile slices saved in: $OUTDIR/slices/"
+ls -la "$OUTDIR/slices/"*.svg 2>/dev/null | wc -l | xargs -I{} echo "  {} SVG slices generated"
+echo "Primitives saved to: $OUTDIR/primitives.json"
+echo "Mesh info saved to: $OUTDIR/mesh-info.json"
+echo ""
+echo "=== Analysis Complete ==="

skills/openscad/scripts/openscad-validate.sh

@@ -0,0 +1,92 @@
+#!/usr/bin/env bash
+# openscad-validate.sh — Validate .scad files with structured error output
+# Runs OpenSCAD in strict mode and parses errors into actionable categories
+set -euo pipefail
+
+OPENSCAD="${OPENSCAD_BIN:-$(command -v openscad || echo /opt/homebrew/bin/openscad)}"
+
+usage() {
+    echo "Usage: openscad-validate.sh <file.scad> [-D 'var=val' ...]"
+    exit 1
+}
+
+[[ $# -lt 1 ]] && usage
+
+scad_file="$1"
+shift
+
+if [[ ! -f "$scad_file" ]]; then
+    echo "ERROR: File not found: $scad_file" >&2
+    exit 1
+fi
+
+tmpdir=$(mktemp -d /tmp/openscad-validate-XXXXXX)
+trap 'rm -rf "$tmpdir"' EXIT
+
+stl_out="$tmpdir/check.stl"
+echo_out="$tmpdir/check.echo"
+
+# Run OpenSCAD in strict mode
+output=$("$OPENSCAD" \
+    --check-parameters=true \
+    --check-parameter-ranges=true \
+    --hardwarnings \
+    -o "$stl_out" \
+    -o "$echo_out" \
+    "$@" \
+    "$scad_file" 2>&1) || exit_code=$?
+
+exit_code="${exit_code:-0}"
+
+echo "=== Validation Report ==="
+echo "File: $scad_file"
+echo "Exit code: $exit_code"
+
+# Categorize errors
+if echo "$output" | grep -q "Parser error"; then
+    echo "Category: SYNTAX_ERROR"
+    echo "$output" | grep "ERROR:" | head -5
+    echo ""
+    # Extract line number
+    line=$(echo "$output" | sed -n 's/.*line \([0-9]*\).*/\1/p' | head -1)
+    if [[ -n "$line" ]]; then
+        echo "Error at line $line. Context:"
+        sed -n "$((line > 3 ? line - 3 : 1)),${line}p" "$scad_file" 2>/dev/null | cat -n
+    fi
+elif echo "$output" | grep -q "Current top level object is empty"; then
+    echo "Category: EMPTY_MODEL"
+    echo "The model produces no geometry. Check:"
+    echo "  - Are modules being called?"
+    echo "  - Did a difference() remove everything?"
+    echo "  - Are parameter values valid?"
+elif echo "$output" | grep -q "NSOpenGLContext\|GLX\|Unable to create"; then
+    echo "Category: HEADLESS_PREVIEW"
+    echo "PNG preview unavailable (no OpenGL context)."
+    echo "STL export should still work."
+elif echo "$output" | grep -qi "warning"; then
+    echo "Category: WARNING"
+    echo "$output" | grep -i "warning" | head -10
+else
+    echo "Category: OK"
+fi
+
+# Show echo output if present
+if [[ -f "$echo_out" ]] && [[ -s "$echo_out" ]]; then
+    echo ""
+    echo "=== Echo Output ==="
+    cat "$echo_out"
+fi
+
+# Show geometry stats if STL was produced
+if [[ -f "$stl_out" ]]; then
+    stl_size=$(wc -c < "$stl_out" | tr -d ' ')
+    if [[ "$stl_size" -gt 0 ]]; then
+        echo ""
+        echo "=== Geometry ==="
+        echo "STL size: $stl_size bytes"
+        # Extract stats from render output
+        echo "$output" | grep -E "(Facets|Vertices|rendering time|Simple):" | head -10
+    fi
+fi
+
+exit "$exit_code"

skills/openscad/templates/bracket.scad

@@ -0,0 +1,69 @@
+// ============================================
+// Template: L-Bracket with Mounting Holes
+// Description: Adjustable L-bracket for wall/shelf mounting
+// ============================================
+
+// --- Parameters ---
+arm_length = 50;     // [mm] horizontal arm
+leg_length = 40;     // [mm] vertical leg
+width = 25;          // [mm] bracket width
+thickness = 4;       // [mm] material thickness
+fillet_r = 8;        // [mm] inner fillet radius
+
+// Mounting holes
+hole_d = 5;          // [mm] hole diameter
+hole_inset = 10;     // [mm] hole center from edges
+countersink = true;  // countersink holes
+cs_d = 9;            // [mm] countersink diameter
+cs_depth = 2;        // [mm] countersink depth
+
+// --- Quality ---
+$fn = 64;
+
+// --- Render ---
+bracket();
+
+// --- Modules ---
+module bracket() {
+    difference() {
+        union() {
+            // Horizontal arm
+            cube([arm_length, width, thickness]);
+
+            // Vertical leg
+            cube([thickness, width, leg_length]);
+
+            // Inner fillet for strength
+            translate([thickness, 0, thickness])
+                fillet(fillet_r, width);
+        }
+
+        // Arm mounting holes
+        translate([arm_length - hole_inset, width/2, -0.01])
+            mounting_hole(hole_d, thickness, countersink, cs_d, cs_depth);
+
+        // Leg mounting holes
+        translate([-0.01, width/2, leg_length - hole_inset])
+            rotate([0, 90, 0])
+                mounting_hole(hole_d, thickness, countersink, cs_d, cs_depth);
+    }
+}
+
+module fillet(r, w) {
+    difference() {
+        cube([r, w, r]);
+        translate([r, -0.01, r])
+            rotate([-90, 0, 0])
+                cylinder(r=r, h=w + 0.02);
+    }
+}
+
+module mounting_hole(d, h, countersink=false, cs_d=0, cs_depth=0) {
+    union() {
+        cylinder(d=d, h=h + 0.02);
+        if (countersink) {
+            translate([0, 0, h - cs_depth + 0.01])
+                cylinder(d1=d, d2=cs_d, h=cs_depth);
+        }
+    }
+}

skills/openscad/templates/enclosure.scad

@@ -0,0 +1,119 @@
+// ============================================
+// Template: Parametric Electronics Enclosure
+// Description: Box with lid, screw posts, ventilation
+// ============================================
+
+// --- Parameters ---
+width = 80;          // [mm] inner width (X)
+depth = 60;          // [mm] inner depth (Y)
+height = 35;         // [mm] inner height (Z)
+wall = 2.5;          // [mm] wall thickness
+corner_r = 3;        // [mm] corner radius
+lid_height = 8;      // [mm] lid inner height
+lip = 1.5;           // [mm] lid overlap lip
+tolerance = 0.3;     // [mm] fit tolerance
+
+// Screw posts
+screw_d = 3;         // [mm] screw hole diameter
+post_d = 7;          // [mm] post outer diameter
+post_inset = 5;      // [mm] post inset from inner wall
+
+// Ventilation
+vent_slots = 5;      // number of vent slots
+vent_width = 2;      // [mm] slot width
+vent_length = 20;    // [mm] slot length
+
+// --- Quality ---
+$fn = 64;
+eps = 0.01;  // epsilon for clean booleans
+
+// --- Assertions ---
+assert(wall >= 1.2, "wall too thin for FDM (min 1.2mm)");
+assert(width > 2 * wall, "inner width must be positive");
+assert(depth > 2 * wall, "inner depth must be positive");
+assert(height > wall, "inner height must be positive");
+
+// --- Render ---
+// Show both parts side by side
+box_bottom();
+translate([width + wall * 2 + 10, 0, 0]) box_lid();
+
+// --- Modules ---
+module box_bottom() {
+    difference() {
+        // Outer shell
+        rounded_box([width + 2*wall, depth + 2*wall, height + wall], corner_r);
+
+        // Inner cavity
+        translate([wall, wall, wall])
+            rounded_box([width, depth, height + wall + 1], max(corner_r - wall, 0.5));
+
+        // Ventilation slots on one side
+        translate([wall + (width - (vent_slots * (vent_width + 3))) / 2, -1, height/2])
+            for (i = [0:vent_slots-1])
+                translate([i * (vent_width + 3), 0, 0])
+                    cube([vent_width, wall + 2, vent_length]);
+    }
+
+    // Screw posts
+    for (pos = screw_post_positions())
+        translate([pos.x, pos.y, wall])
+            screw_post(post_d, screw_d, height - 2);
+
+    // Lid lip (inner ridge)
+    difference() {
+        translate([wall - lip, wall - lip, height + wall - lip])
+            rounded_box([width + 2*lip, depth + 2*lip, lip], max(corner_r - wall + lip, 0.5));
+        translate([wall, wall, height + wall - lip - 0.01])
+            rounded_box([width, depth, lip + 0.02], max(corner_r - wall, 0.5));
+    }
+}
+
+module box_lid() {
+    difference() {
+        // Outer lid
+        rounded_box([width + 2*wall, depth + 2*wall, lid_height + wall], corner_r);
+
+        // Inner cavity
+        translate([wall, wall, -0.01])
+            rounded_box([width, depth, lid_height + 0.02], max(corner_r - wall, 0.5));
+    }
+
+    // Lip insert (fits inside bottom lip)
+    translate([wall + tolerance, wall + tolerance, 0])
+        difference() {
+            rounded_box(
+                [width - 2*tolerance, depth - 2*tolerance, lip],
+                max(corner_r - wall - tolerance, 0.5)
+            );
+            translate([lip, lip, -0.01])
+                rounded_box(
+                    [width - 2*lip - 2*tolerance, depth - 2*lip - 2*tolerance, lip + 0.02],
+                    max(corner_r - wall - lip - tolerance, 0.5)
+                );
+        }
+}
+
+module rounded_box(size, r) {
+    hull() {
+        for (x = [r, size.x - r])
+            for (y = [r, size.y - r])
+                translate([x, y, 0])
+                    cylinder(r=r, h=size.z);
+    }
+}
+
+module screw_post(outer_d, inner_d, h) {
+    difference() {
+        cylinder(d=outer_d, h=h);
+        translate([0, 0, -0.01])
+            cylinder(d=inner_d, h=h + 0.02);
+    }
+}
+
+function screw_post_positions() = [
+    [wall + post_inset, wall + post_inset, 0],
+    [wall + width - post_inset, wall + post_inset, 0],
+    [wall + post_inset, wall + depth - post_inset, 0],
+    [wall + width - post_inset, wall + depth - post_inset, 0]
+];

skills/openscad/templates/printable-lib.scad

@@ -0,0 +1,152 @@
+// ============================================
+// printable-lib.scad — Reusable modules for 3D printing
+// Include with: use <printable-lib.scad>
+// ============================================
+
+eps = 0.01;  // epsilon for clean boolean operations
+
+// --- Clearance helpers ---
+// Returns clearance value for different fit types
+function fit_clearance(kind="close") =
+    kind == "press"  ? 0.15 :
+    kind == "close"  ? 0.25 :
+    kind == "loose"  ? 0.40 :
+    kind == "slide"  ? 0.30 : 0.25;
+
+// --- Shell / Hollow box ---
+module shell_box(outer=[60,40,20], wall=2, floor=2) {
+    assert(wall >= 1.2, "wall too thin for FDM (min 1.2mm)");
+    assert(floor >= 0.8, "floor too thin (min 0.8mm)");
+    difference() {
+        cube(outer);
+        translate([wall, wall, floor])
+            cube([outer.x - 2*wall, outer.y - 2*wall, outer.z - floor + eps]);
+    }
+}
+
+// --- Rounded box (hull-based) ---
+module rounded_box(size, r=2) {
+    hull() {
+        for (x = [r, size.x - r])
+            for (y = [r, size.y - r])
+                translate([x, y, 0])
+                    cylinder(r=r, h=size.z);
+    }
+}
+
+// --- Screw clearance hole ---
+module screw_clearance_hole(d=3, h=10, fit="close") {
+    cylinder(h=h + 2*eps, d=d + fit_clearance(fit), $fn=48);
+}
+
+// --- Counterbore hole (for socket head cap screws) ---
+// Head pocket at entry side (top), shaft goes through
+module counterbore_hole(shaft_d=3, head_d=6, head_h=3, h=12) {
+    union() {
+        screw_clearance_hole(shaft_d, h);
+        translate([0, 0, h - head_h + eps])
+            cylinder(h=head_h + eps, d=head_d, $fn=48);
+    }
+}
+
+// --- Countersink hole ---
+module countersink_hole(d=3, cs_d=6, cs_h=2, h=10) {
+    union() {
+        cylinder(d=d, h=h + 2*eps, $fn=48);
+        translate([0, 0, h - cs_h + eps])
+            cylinder(d1=d, d2=cs_d, h=cs_h, $fn=48);
+    }
+}
+
+// --- Heat-set insert boss ---
+module heatset_boss(insert_d=4.6, insert_h=5, wall=2, h=8) {
+    assert(wall >= 1.6, "boss wall too thin for heat-set insert");
+    difference() {
+        cylinder(h=h, d=insert_d + 2*wall, $fn=64);
+        translate([0, 0, -eps])
+            cylinder(h=insert_h + 2*eps, d=insert_d, $fn=64);
+    }
+}
+
+// --- Screw post (solid post with hole) ---
+module screw_post(outer_d=7, inner_d=3, h=10) {
+    difference() {
+        cylinder(d=outer_d, h=h, $fn=48);
+        translate([0, 0, -eps])
+            cylinder(d=inner_d, h=h + 2*eps, $fn=48);
+    }
+}
+
+// --- Structural rib / gusset ---
+module rib(len=20, height=12, thick=2) {
+    linear_extrude(height=thick)
+        polygon([[0, 0], [len, 0], [0, height]]);
+}
+
+// --- Chamfer edge (for print-friendly overhangs) ---
+module chamfer_edge(length=10, size=1) {
+    translate([0, 0, -eps])
+        linear_extrude(height=length)
+            polygon([[0, 0], [size, 0], [0, size]]);
+}
+
+// --- Snap-fit tab ---
+// Creates a cantilever snap tab extending along Y with a hook at the end
+module snap_tab(width=8, length=6, thick=1.5, overhang=0.8) {
+    union() {
+        // Cantilever arm
+        cube([width, length, thick]);
+        // Hook at the end (rotated extrusion for clean manifold)
+        translate([0, length - eps, 0])
+            rotate([90, 0, 90])
+                linear_extrude(height=width)
+                    polygon([[0, 0], [thick + eps, 0], [thick/2, overhang]]);
+    }
+}
+
+// --- Text emboss/deboss helper ---
+// Use with difference() to deboss or union() to emboss
+module text_label(txt="Label", size=8, depth=1, font="Liberation Sans:style=Bold",
+                  halign="center", valign="center") {
+    linear_extrude(height=depth)
+        text(txt, size=size, font=font, halign=halign, valign=valign);
+}
+
+// --- Ventilation grille ---
+module vent_grille(area_w=30, area_h=15, slot_w=2, slot_gap=2, depth=2) {
+    n_slots = floor(area_h / (slot_w + slot_gap));
+    for (i = [0:n_slots-1])
+        translate([0, i * (slot_w + slot_gap), 0])
+            cube([area_w, slot_w, depth + 2*eps]);
+}
+
+// --- PCB standoff array ---
+module pcb_standoffs(positions, height=5, outer_d=6, hole_d=2.5) {
+    for (pos = positions)
+        translate(pos)
+            difference() {
+                cylinder(d=outer_d, h=height, $fn=32);
+                translate([0, 0, -eps])
+                    cylinder(d=hole_d, h=height + 2*eps, $fn=32);
+            }
+}
+
+// --- Profile with rounded corners (2D) ---
+// Use with linear_extrude() — preferred over hull() of cylinders
+module rounded_rect_2d(size, r=2) {
+    offset(r=r)
+        square([size.x - 2*r, size.y - 2*r], center=true);
+}
+
+// --- Lid lip (for box closures) ---
+module lid_lip(outer_size, wall=2, lip_h=2, lip_w=1.2, tol=0.25) {
+    difference() {
+        rounded_box([outer_size.x, outer_size.y, lip_h], r=2);
+        translate([lip_w + tol, lip_w + tol, -eps])
+            rounded_box([
+                outer_size.x - 2*(lip_w + tol),
+                outer_size.y - 2*(lip_w + tol),
+                lip_h + 2*eps
+            ], r=max(2 - lip_w, 0.5));
+    }
+}