name: brainstorm
description: Use at the START of any request to design, model, create, build, or 3D-print a physical part or assembly in brepjs — a bracket, enclosure, mount, gear, gridfinity bin, fixture, knob, adapter, and the like. This is the entry point to the brepjs CAD pipeline: it turns a vague or natural-language request ("a bracket for my router", "a gridfinity bin") into an explicit, buildable spec (dimensions in mm, datums, features, material/finish, tolerances) before any geometry is written, then hands off to brepjs:design → implement → verify → polish. Runs in the main session so it can ask the user clarifying questions.
version: 0.1.0
Brainstorm a brepjs part
Turn a natural-language request into an explicit spec the rest of the pipeline can build from.
This is step 1 — the brief. You produce a written spec, not geometry. Run this in the main
session (you can talk to the user here); the implement/verify/polish workers cannot.
What a spec contains
- Overall envelope — bounding dimensions in mm (W × D × H).
- Datums — where the part sits: base plane at origin? centered? a mounting face?
- Features — holes (size + pattern), bosses, pockets, ribs, fillets/chamfers, threads, cavities.
- Material / process — FDM plastic (default for makers), metal, decorative vs functional.
- Tolerances — fit class for holes/slots; or "non-critical".
- Assumptions — everything you inferred so the user can correct it.
Scoping pattern — how to ask well
Scoping is mostly open-ended, so default to prose questions asked inline here, not forms:
You want a bracket. To scope it: what surface does it mount to, what does it hold (load + size),
and roughly what envelope should it fit in?
Reserve AskUserQuestion (multiple-choice) for concrete, mutually-exclusive decisions once
the shape is otherwise clear — e.g. fastener size (M3/M4/M5), material (FDM vs metal), mounting
style (flush/tab/flange), tolerance class, edge finish (sharp/fillet/chamfer). Never force a vague
request into a multiple-choice form before the user has described intent — that asks them to pick
before they've spoken.
Resolve, don't interrogate: if the request + sensible defaults already determine a field, fill it
and state the assumption rather than asking.
Domain defaults (load when the request matches)
Maker conventions inform what to assume and what to ask. These live with the implement skill:
- FDM clearance holes / walls / fits →
../implement/references/fdm-conventions.md
- Snap-fits, press-fits, heat-set inserts →
../implement/references/mechanical-joints.md
- Gridfinity 42 mm grid / magnets / stacking →
../implement/references/gridfinity.md
Output
Emit the spec as a compact markdown table (envelope, datums, features, material, tolerances,
assumptions). In the /brepjs:cad pipeline this is the gate where the orchestrator confirms the
spec with the user; standalone, hand it to brepjs:design to decompose into a build sequence.
