andymai/brepjs/brainstorm

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.