Onshape FeatureScript Generator

---

name: onshape-featurescript

description">Generate Onshape FeatureScript code for custom CAD features and parametric parts. Specializes in dust collection fittings library (wyes, elbows, adapters, crosses). Use when user asks to: (1) create FS features (gears, fittings, brushes), (2) modify existing FS, (3) debug FS errors, (4) build libraries with consistent patterns (enums, shells, labels). Patterns for Z-axis fittings, wrapped labels, safe unions/shells. Triggers: 'Onshape FS for X', 'FeatureScript wye/elbow', 'dust fitting'.</description>

---

# Onshape FeatureScript Generator

Quick Start

Analyze request → Match pattern → Gen FS code → Validate logic.

**Core Workflow**:

1. **Precondition**: Enums/lengths/reals w/ bounds.

2. **Body**: Sketches → Extrudes → Booleans → Shell → Wrap/Thicken labels.

3. **Pitfalls**: qOwnedByBody(finalBody), if/else (no ternary lengths), cylinder(coordSystem).

Key Patterns (Memorize)

```

export enum AlignmentStyle { Centered, Tangent, Offset };

if (definition.alignment == AlignmentStyle.Offset) { isLength(def.offsetDistance...); }

```

```

var capFaces = qFacesParallelToDirection(qOwnedByBody(finalBody, EntityType.FACE), vector(0,1,0));

```

```

qUnion([qCreatedBy(id+"inlet", EntityType.BODY), ...]);

```

Dust Fittings Lib

Z-axis: Inlet Z=0 (-Z), Outlet Z=trans (+Z), Branch +X.

See [FITTINGS.md](references/fittings.md) for full spec/pitfalls.

Resources

Gen code → User pastes to Onshape FS editor.