gen · diff
git:20261102.ef2be30 to git:20261106.8c298cb
24 added, 14 removed. Audit A to A.
---
name: gen
- description: Generate PartCAD geometry from a description, automatically deciding whether the request is a single part, a multi-part assembly, or a 2D sketch and following the matching flow. Use for /pc:gen or when the user asks to generate, create, or model something in PartCAD without saying whether it is a part, an assembly, or a sketch.
+ description: Generate PartCAD geometry from a description, automatically deciding whether the request is a single part, a multi-part assembly, a scene (an arrangement of objects - a room, an interior, a workcell, a world), or a 2D sketch and following the matching flow. Use for /pc:gen or when the user asks to generate, create, or model something in PartCAD without saying whether it is a part, an assembly, a scene, or a sketch.
---
# pc:gen
Entry point for PartCAD generation when the user has not said whether they want a
- single **part**, an **assembly**, or a 2D **sketch**. The text after the command
- (`$ARGUMENTS`) is the description of what to build. Decide which it is, tell the
+ single **part**, an **assembly**, a **scene**, or a 2D **sketch**. The text after
+ the command (`$ARGUMENTS`) is the description of what to build. Decide which it is, tell the
user your choice, then follow that flow — passing the same description through.
- ## Decide: part, assembly, or sketch?
+ ## Decide: part, assembly, scene, or sketch?
- **Part** → `/pc:gen-part`. One continuous piece of 3D geometry — a bracket, a
gear, a housing, a knob. Modeled as a single script, even when intricate.
- **Assembly** → `/pc:gen-assembly`. Several distinct 3D components that fit or
move relative to each other — a gearbox, a robot arm, a body with a lid,
anything joined by fasteners.
+ - **Scene** → `/pc:gen-scene`. Objects arranged where they stand rather than
+ put together into a product — a room, a building interior, an office floor, a
+ workcell, a table laid out, a world to simulate something in.
- **Sketch** → `/pc:gen-sketch`. A 2D profile, outline, or blueprint — a gasket
shape, a plate outline, a cross-section to be extruded later.
Heuristics:
- "2D", "profile", "outline", "sketch", "cross-section", "blueprint", "trace
this drawing" → **sketch**.
- One noun, "a"/"single", one manufacturing process, one printed/machined piece
→ **part**.
- Plurals, "with", "attached to", "... and a ...", moving joints, fasteners, or
named sub-components → **assembly**.
+ - A place or a setting — "a room", "an apartment", "an office", "a kitchen", "a
+ workcell", "a garden", "on the Moon", "in orbit" — or things "standing",
+ "laid out" or "arranged" somewhere → **scene**. A product *in* such a place
+ is still an assembly, which the scene then places.
If it is genuinely ambiguous, ask one short question. Otherwise proceed with your
best judgment and state which you picked — the user can redirect.
A physical claim in the description — it stands, it does not tip, it floats, it
holds a load, it works under water or on the Moon — is part of the request, not
- decoration: carry it into the part or assembly flow, which makes the result
- ready to simulate and checks the claim with `pc sim`.
+ decoration: carry it into the part, assembly or scene flow, which makes the
+ result ready to simulate and checks the claim with `pc sim`.
## Then
- Sketch → follow **`/pc:gen-sketch`**.
- Part → follow **`/pc:gen-part`**.
- Assembly → follow **`/pc:gen-assembly`** (which itself uses `/pc:gen-part` for
any missing components).
+ - Scene → follow **`/pc:gen-scene`** (which models its objects as `basic`
+ primitives, and uses `/pc:gen-part` and `/pc:gen-assembly` where more detail
+ is called for).
- All three settle the dimensions before they model: `/pc:gen-sketch` measures
+ All four settle the dimensions before they model: `/pc:gen-sketch` measures
the targets out of whatever the input is — a description, a drawing, a photo, a
- 3D file — and iterates a sketch until it measures the same, and the part and
- assembly flows run it on temporary sketches first, then measure their own result
- against the same numbers. Pass every reference image, drawing or file the user
- gave through to the flow you pick: those are what the dimensions are measured
- from.
+ 3D file — and iterates a sketch until it measures the same, and the part,
+ assembly and scene flows run it on temporary sketches first, then measure their
+ own result against the same numbers. Pass every reference image, drawing or
+ file the user gave through to the flow you pick: those are what the dimensions
+ are measured from.
- The part and the assembly flows write down what the object is required to be
- as its `requirements:` before judging the result against them, and
+ The part, assembly and scene flows write down what the object is required to
+ be as its `requirements:` before judging the result against them, and
`/pc:validate` gives a verdict on every one of them afterwards.